Helmand river hydrologic studies using ALOS PALSAR InSAR and ENVISAT altimetry

Science.gov (United States)

Lu, Zhong; Kim, J.-W.; Lee, H.; Shum, C.K.; Duan, J.; Ibaraki, M.; Akyilmaz, O.; Read, C.-H.

2009-01-01

The Helmand River wetland represents the only fresh-water resource in southern Afghanistan and one of the least mapped water basins in the world. The relatively narrow wetland consists of mostly marshes surrounded by dry lands. In this study, we demonstrate the use of the Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) Interferometric SAR (InSAR) to detect the changes of the Helmand River wetland water level. InSAR images are combined with the geocentric water level measurements from the retracked high-rate (18-Hz) Environmental Satellite (Envisat) radar altimetry to construct absolute water level changes over the marshes. It is demonstrated that the integration of the altimeter and InSAR can provide spatio-temporal measurements of water level variation over the Helmand River marshes where in situ measurements are absent. ?? Taylor & Francis Group, LLC.

Analysis of the Effect of Radio Frequency Interference on Repeat Track Airborne InSAR System

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Ding Bin

2012-03-01

Full Text Available The SAR system operating at low frequency is susceptible to Radio Frequency Interference (RFI from television station, radio station, and some other civil electronic facilities. The presence of RFI degrades the SAR image quality, and obscures the targets in the scene. Furthermore, RFI can cause interferometric phase error in repeat track InSAR system. In order to analyze the effect of RFI on interferometric phase of InSAR, real measured RFI signal are added on cone simulated SAR echoes. The imaging and interferometric processing results of both the RFI-contaminated and raw data are given. The effect of real measured RFI signal on repeat track InSAR system is analyzed. Finally, the imaging and interferometric processing results of both with and without RFI suppressed of the P band airborne repeat track InSAR real data are presented, which demonstrates the efficiency of the RFI suppression method in terms of decreasing the interferometric phase errors caused by RFI.

Sea ice local surface topography from single-pass satellite InSAR measurements: a feasibility study

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W. Dierking

2017-08-01

Full Text Available Quantitative parameters characterizing the sea ice surface topography are needed in geophysical investigations such as studies on atmosphere–ice interactions or sea ice mechanics. Recently, the use of space-borne single-pass interferometric synthetic aperture radar (InSAR for retrieving the ice surface topography has attracted notice among geophysicists. In this paper the potential of InSAR measurements is examined for several satellite configurations and radar frequencies, considering statistics of heights and widths of ice ridges as well as possible magnitudes of ice drift. It is shown that, theoretically, surface height variations can be retrieved with relative errors  ≤  0.5 m. In practice, however, the sea ice drift and open water leads may contribute significantly to the measured interferometric phase. Another essential factor is the dependence of the achievable interferometric baseline on the satellite orbit configurations. Possibilities to assess the influence of different factors on the measurement accuracy are demonstrated: signal-to-noise ratio, presence of a snow layer, and the penetration depth into the ice. Practical examples of sea surface height retrievals from bistatic SAR images collected during the TanDEM-X Science Phase are presented.

Surface motion of active rock glaciers in the Sierra Nevada, California, USA: inventory and a case study using InSAR

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L. Liu; C.I. Millar; R.D. Westfall; H.A. Zebker

2013-01-01

Despite the abundance of rock glaciers in the Sierra Nevada of California, USA, few efforts have been made to measure their surface flow. Here we use the interferometric synthetic aperture radar (InSAR) technique to compile a~benchmark inventory describing the kinematic state of 59 active rock glaciers in this region. Statistically, these rock glaciers moved at...

Monitoring the Sumatra volcanic arc with InSAR

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Chaussard, E.; Hong, S.; Amelung, F.

2009-12-01

The Sumatra volcanic arc is the result of the subduction of the Indo-Australian plate under the Sunda plate. The arc consists of 35 known volcanic centers, subaerials on the west coast of the Sumatra and Andaman Islands and submarines between these islands. Six active centers are known in the Sumatra volcanic arc. Surface deformation in volcanic areas usually indicates movement of magma or hydrothermal fluids at depth. Here we present a satellite-based Interferometric synthetic aperture radar (InSAR) survey of the Sumatra volcanic arc using ALOS data. Spanning the years 2007 to beginning of 2009, our survey reveals the background level of activity of the 35 volcanoes. We processed data from 40 tracks (24 in descending orbit and 16 in ascending orbit) to cover the whole Sumatra arc. In the first results five of these six known active centers show no sign of activity: Dempo, Kaba, Marapi, Talang and Peuet. The remaining active volcano, Mount Kerinci, has an ambiguous signal. We used pair-wise logic and InSAR time series of the available ALOS data to determine if the observed InSAR signal is caused by ground deformation or by atmospheric delays.

Measuring the Impact of Wildfire on Active Layer Thickness in a Discontinuous Permafrost region using Interferometric Synthetic Aperture Radar (InSAR)

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Michaelides, R. J.; Schaefer, K. M.; Zebker, H. A.; Liu, L.; Chen, J.; Parsekian, A.

2017-12-01

In permafrost regions, the active layer is defined as the uppermost portion of the permafrost table that is subject to annual freeze/thaw cycles. The active layer plays a crucial role in surface processes, surface hydrology, and vegetation succession; furthermore, trapped methane, carbon dioxide, and other greenhouse gases in permafrost are released into the atmosphere as permafrost thaws. A detailed understanding of active layer dynamics is therefore critical towards understanding the interactions between permafrost surface processes, freeze/thaw cycles, and climate-especially in regions across the Arctic subject to long-term permafrost degradation. The Yukon-Kuskokwim (YK) delta in southwestern Alaska is a region of discontinuous permafrost characterized by surface lakes, wetlands, and thermokarst depressions. Furthermore, extensive wildfires have burned across the YK delta in 2006, 2007, and 2015, impacting vegetation cover, surface soil moisture, and the active layer. Using data from the ALOS PALSAR, ALOS-2 PALSAR-2, and Sentinel-1A/B space borne synthetic aperture radar (SAR) systems, we generate a series of interferograms over a study site in the YK delta spanning 2007-2011, and 2014-present. Using the ReSALT (Remotely-Sensed Active Layer Thickness) technique, we demonstrate that active layer can be characterized over most of the site from the relative interferometric phase difference due to ground subsidence and rebound associated with the seasonal active layer freeze/thaw cycle. Additionally, we show that this technique successfully discriminates between burned and unburned regions, and can resolve increases in active layer thickness in burned regions on the order of 10's of cms. We use the time series of interferograms to discuss permafrost recovery following wildfire burn, and compare our InSAR observations with GPR and active layer probing data from a 2016 summer field campaign to the study site. Finally, we compare the advantages and disadvantages of

Estimating tropical forest structure using LIDAR AND X-BAND INSAR

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Palace, M. W.; Treuhaft, R. N.; Keller, M. M.; Sullivan, F.; Roberto dos Santos, J.; Goncalves, F. G.; Shimbo, J.; Neumann, M.; Madsen, S. N.; Hensley, S.

2013-12-01

Tropical forests are considered the most structurally complex of all forests and are experiencing rapid change due to anthropogenic and climatic factors. The high carbon stocks and fluxes make understanding tropical forests highly important to both regional and global studies involving ecosystems and climate. Large and remote areas in the tropics are prime targets for the use of remotely sensed data. Radar and lidar have previously been used to estimate forest structure, with an emphasis on biomass. These two remote sensing methods have the potential to yield much more information about forest structure, specifically through the use of X-band radar and waveform lidar data. We examined forest structure using both field-based and remotely sensed data in the Tapajos National Forest, Para, Brazil. We measured multiple structural parameters for about 70 plots in the field within a 25 x 15 km area that have TanDEM-X single-pass horizontally and vertically polarized radar interferometric data. High resolution airborne lidar were collected over a 22 sq km portion of the same area, within which 33 plots were co-located. Preliminary analyses suggest that X-band interferometric coherence decreases by about a factor of 2 (from 0.95 to 0.45) with increasing field-measured vertical extent (average heights of 7-25 m) and biomass (10-430 Mg/ha) for a vertical wavelength of 39 m, further suggesting, as has been observed at C-band, that interferometric synthetic aperture radar (InSAR) is substantially more sensitive to forest structure/biomass than SAR. Unlike InSAR coherence versus biomass, SAR power at X-band versus biomass shows no trend. Moreover, airborne lidar coherence at the same vertical wavenumbers as InSAR is also shown to decrease as a function of biomass, as well. Although the lidar coherence decrease is about 15% more than the InSAR, implying that lidar penetrates more than InSAR, these preliminary results suggest that X-band InSAR may be useful for structure and

INSAR observations of the DPRK event series

Science.gov (United States)

Mellors, R. J.; Ford, S. R.; Walter, W. R.

2017-12-01

Interferometric synthetic aperture radar (INSAR) data have revealed signals associated with the recent DPRK events in 2016 and 2017. These signals include decorrelation and indications of subsidence. Both standard phase differences and amplitude offsets are calculated. We show results of INSAR analysis as conducted using C and L band data and investigate the causes of the decorrelation (e.g. subsidence, landslide, or spall) and compare the observed signal with numerical models of deformation and seismic observations. A time series approach is applied to constrain post-event deformation at the weeks to months' timescale. We compare the INSAR observations of the DPRK tests with previous observations of events at other source regions using ERS archive data, which revealed a variety of post-seismic signatures. The signatures are evaluated with respect to the known geology and causes, including long-term surface relaxation and possible groundwater/thermal effects. Particular focus is on the sites on Pahute and Rainier Mesa, which displayed long-term subsidence signals that extended for several years after the explosions. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC

Calibration of a Land Subsidence Model Using InSAR Data via the Ensemble Kalman Filter.

Science.gov (United States)

Li, Liangping; Zhang, Meijing; Katzenstein, Kurt

2017-11-01

The application of interferometric synthetic aperture radar (InSAR) has been increasingly used to improve capabilities to model land subsidence in hydrogeologic studies. A number of investigations over the last decade show how spatially detailed time-lapse images of ground displacements could be utilized to advance our understanding for better predictions. In this work, we use simulated land subsidences as observed measurements, mimicking InSAR data to inversely infer inelastic specific storage in a stochastic framework. The inelastic specific storage is assumed as a random variable and modeled using a geostatistical method such that the detailed variations in space could be represented and also that the uncertainties of both characterization of specific storage and prediction of land subsidence can be assessed. The ensemble Kalman filter (EnKF), a real-time data assimilation algorithm, is used to inversely calibrate a land subsidence model by matching simulated subsidences with InSAR data. The performance of the EnKF is demonstrated in a synthetic example in which simulated surface deformations using a reference field are assumed as InSAR data for inverse modeling. The results indicate: (1) the EnKF can be used successfully to calibrate a land subsidence model with InSAR data; the estimation of inelastic specific storage is improved, and uncertainty of prediction is reduced, when all the data are accounted for; and (2) if the same ensemble is used to estimate Kalman gain, the analysis errors could cause filter divergence; thus, it is essential to include localization in the EnKF for InSAR data assimilation. © 2017, National Ground Water Association.

Remotely Sensed Active Layer Thickness (ReSALT at Barrow, Alaska Using Interferometric Synthetic Aperture Radar

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Kevin Schaefer

2015-03-01

Full Text Available Active layer thickness (ALT is a critical parameter for monitoring the status of permafrost that is typically measured at specific locations using probing, in situ temperature sensors, or other ground-based observations. Here we evaluated the Remotely Sensed Active Layer Thickness (ReSALT product that uses the Interferometric Synthetic Aperture Radar technique to measure seasonal surface subsidence and infer ALT around Barrow, Alaska. We compared ReSALT with ground-based ALT obtained using probing and calibrated, 500 MHz Ground Penetrating Radar at multiple sites around Barrow. ReSALT accurately reproduced observed ALT within uncertainty of the GPR and probing data in ~76% of the study area. However, ReSALT was less than observed ALT in ~22% of the study area with well-drained soils and in ~1% of the area where soils contained gravel. ReSALT was greater than observed ALT in some drained thermokarst lake basins representing ~1% of the area. These results indicate remote sensing techniques based on InSAR could be an effective way to measure and monitor ALT over large areas on the Arctic coastal plain.

INSAR OF AQUATIC BODIES

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P. Tarikhi

2012-07-01

Full Text Available Radar remote sensing is a new earth observation technology with promising results and future. InSAR is a sophisticated radar remote sensing technique for combining synthetic aperture radar (SAR single look complex images to form interferogram and utilizing its phase contribution to land topography, surface movement and target velocity. In recent years considerable applications of Interferometric SAR technique have been developed. It is an established technique for precise assessment of land surface movements, and generating high quality digital elevation models (DEM from space-borne and airborne data. InSAR is able to produce DEMs with the precision of a couple of ten meters whereas its movement map results have sub-centimeter precision. The technique has many applications in the context of earth sciences such as topographic mapping, environmental modelling, rainfall-runoff studies, landslide hazard zonation, and seismic source modelling. Nevertheless new developments are taking place in the application of InSAR for aquatic bodies. We have observed that using SAR Interferometry technique for aquatic bodies with the maximum temporal baseline of 16 seconds for image pairs shows considerable results enabling us to determine the direction of sea surface motion in a large area, estimate the sea surface fluctuations in the direction of sensor line-of-the-sight, detect wave pattern and the sea surface disturbance and whether the water motion is bulk and smooth or otherwise. This paper presents our experience and achievements on this new topic through discussing the facts and conditions for the use of InSAR technique. The method has been examined for Haiti, Dominican Republic, Western Chile and Western Turkey coast areas and inland lakes however ground truth data is needed for final verification. This technique scheduled to be applied in some other sites for which the proper data is available.

Confined aquifer head measurements and storage properties in the San Luis Valley, Colorado, from spaceborne InSAR observations

Science.gov (United States)

Chen, Jingyi; Knight, Rosemary; Zebker, Howard A.; Schreüder, Willem A.

2016-05-01

Interferometric Synthetic Aperture Radar (InSAR), a remote sensing technique for measuring centimeter-level surface deformation, is used to estimate hydraulic head in the confined aquifer of the San Luis Valley (SLV), Colorado. Reconstructing head measurements from InSAR in agricultural regions can be difficult, as InSAR phase data are often decorrelated due to vegetation growth. Analysis of 17 L-band ALOS PALSAR scenes, acquired between January 2007 and March 2011, demonstrates that comprehensive InSAR deformation measurements can be recovered over the vegetated groundwater basin with an improved processing strategy. Local skeletal storage coefficients and time delays between the head change and deformation are estimated through a joint InSAR-well data analysis. InSAR subsidence estimates are transformed to head changes with finer temporal and spatial resolution than is possible using existing well records alone. Both InSAR and well data suggest that little long-term water-storage loss occurred in the SLV over the study period and that inelastic compaction was negligible. The seasonal head variations derived from InSAR are consistent with the existing well data at most locations where confined aquifer pumping activity dominates. Our results demonstrate the advantages of InSAR measurements for basin-wide characterization of aquifer storage properties and groundwater levels over agricultural regions.

Slope Stability Assessment of the Sarcheshmeh Landslide, Northeast Iran, Investigated Using InSAR and GPS Observations

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Mahdi Motagh

2013-07-01

Full Text Available The detection and monitoring of mass movement of susceptible slopes plays a key role in mitigating hazards and potential damage associated with creeping slopes and landslides. In this paper, we use observations from both Interferometric Synthetic Aperture Radar (InSAR and Global Positioning System (GPS to assess the slope stability of the Sarcheshmeh ancient landslide in the North Khorasan province of northeast Iran. InSAR observations were obtained by the time-series analysis of Envisat SAR images covering 2004–2006, whereas repeated GPS observations were conducted by campaign measurements during 2010–2012. Surface displacement maps of the Sarcheshmeh landslide obtained from InSAR and GPS are both indicative of slope stability. Hydrogeological analysis suggests that the multi-year drought and lower than average precipitation levels over the last decade might have contributed to the current dormancy of the Sarcheshmeh landslide.

Error estimation in multitemporal InSAR deformation time series, with application to Lanzarote, Canary Islands

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GonzáLez, Pablo J.; FernáNdez, José

2011-10-01

Interferometric Synthetic Aperture Radar (InSAR) is a reliable technique for measuring crustal deformation. However, despite its long application in geophysical problems, its error estimation has been largely overlooked. Currently, the largest problem with InSAR is still the atmospheric propagation errors, which is why multitemporal interferometric techniques have been successfully developed using a series of interferograms. However, none of the standard multitemporal interferometric techniques, namely PS or SB (Persistent Scatterers and Small Baselines, respectively) provide an estimate of their precision. Here, we present a method to compute reliable estimates of the precision of the deformation time series. We implement it for the SB multitemporal interferometric technique (a favorable technique for natural terrains, the most usual target of geophysical applications). We describe the method that uses a properly weighted scheme that allows us to compute estimates for all interferogram pixels, enhanced by a Montecarlo resampling technique that properly propagates the interferogram errors (variance-covariances) into the unknown parameters (estimated errors for the displacements). We apply the multitemporal error estimation method to Lanzarote Island (Canary Islands), where no active magmatic activity has been reported in the last decades. We detect deformation around Timanfaya volcano (lengthening of line-of-sight ˜ subsidence), where the last eruption in 1730-1736 occurred. Deformation closely follows the surface temperature anomalies indicating that magma crystallization (cooling and contraction) of the 300-year shallow magmatic body under Timanfaya volcano is still ongoing.

User-friendly InSAR Data Products: Fast and Simple Timeseries (FAST) Processing

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Zebker, H. A.

2017-12-01

Interferometric Synthetic Aperture Radar (InSAR) methods provide high resolution maps of surface deformation applicable to many scientific, engineering and management studies. Despite its utility, the specialized skills and computer resources required for InSAR analysis remain as barriers for truly widespread use of the technique. Reduction of radar scenes to maps of temporal deformation evolution requires not only detailed metadata describing the exact radar and surface acquisition geometries, but also a software package that can combine these for the specific scenes of interest. Furthermore, the radar range-Doppler radar coordinate system itself is confusing, so that many users find it hard to incorporate even useful products in their customary analyses. And finally, the sheer data volume needed to represent interferogram time series makes InSAR analysis challenging for many analysis systems. We show here that it is possible to deliver radar data products to users that address all of these difficulties, so that the data acquired by large, modern satellite systems are ready to use in more natural coordinates, without requiring further processing, and in as small volume as possible.

Spatial scale of deformation constrained by combinations of InSAR and GPS observations in Southern California

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Lohman, R. B.; Scott, C. P.

2014-12-01

Efforts to understand the buildup and release of strain within the Earth's crust often rely on well-characterized observations of ground deformation, over time scales that include interseismic periods, earthquakes, and transient deformation episodes. Constraints on current rates of surface deformation in 1-, 2- or 3-dimensions can be obtained by examining sets of GPS and Interferometric Synthetic Aperture Radar (InSAR) observations, both alone and in combination. Contributions to the observed signal often include motion along faults, seasonal cycles of subsidence and recharge associated with aquifers, anthropogenic extraction of hydrocarbons, and variations in atmospheric water vapor and ionospheric properties. Here we examine methods for extracting time-varying ground deformation signals from combinations of InSAR and GPS data, real and synthetic, applied to Southern California. We show that two methods for combining the data through removal of a GPS-constrained function (a plane, and filtering) from the InSAR result in a clear tradeoff between the contribution from the two datatypes at diffferent spatial scales. We also show that the contribution to the secular rates at GPS sites from seasonal signals is large enough to be a significant error in this estimation process, and should be accounted for.

Bryan Mound InSAR Analysis U.S. Strategic petroleum Reserve.

Energy Technology Data Exchange (ETDEWEB)

Lord, Anna C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-06-01

The U.S. Strategic Petroleum Reserve (SPR) is a stockpile of emergency crude oil to be tapped into if a disruption in the nation's oil supply occurs. The SPR is comprised of four salt dome sites. Subsidence surveys have been conducted either annually or biennially at all four sites over the life of the program. Monitoring of surface behavior is a first line defense to detecting possible subsurface cavern integrity issues. Over the life of the Bryan Mound site, subsidence rates over abandoned Cavern 3 have continuously been the highest at the site. In an effort to try and understand the subsurface dynamics, specifically over Bryan Mound Cavern 3, historic interferometric synthetic aperture radar (InSAR) data was acquired and processed by TRE Altamira. InSAR involves the processing of multiple satellite synthetic aperture radar scenes acquired across the same location of the Earth's surface at different times to map surface deformation. The analysis of the data has the ability to detect millimeters of motion spanning days, months, year and decades, across specific sites. The intent in regards to the Bryan Mound site was (1) to confirm the higher subsidence rates recorded over abandoned Cavern 3 indicated by land survey and (2) understand the regional surface behavior. This report describes the InSAR analysis results, how those results compare to the historical collection of land survey data, and what additional information the data has provided towards understanding the response recorded at the surface.

Fusion of space-borne multi-baseline and multi-frequency interferometric results based on extended Kalman filter to generate high quality DEMs

Science.gov (United States)

Zhang, Xiaojie; Zeng, Qiming; Jiao, Jian; Zhang, Jingfa

2016-01-01

Repeat-pass Interferometric Synthetic Aperture Radar (InSAR) is a technique that can be used to generate DEMs. But the accuracy of InSAR is greatly limited by geometrical distortions, atmospheric effect, and decorrelations, particularly in mountainous areas, such as western China where no high quality DEM has so far been accomplished. Since each of InSAR DEMs generated using data of different frequencies and baselines has their own advantages and disadvantages, it is therefore very potential to overcome some of the limitations of InSAR by fusing Multi-baseline and Multi-frequency Interferometric Results (MMIRs). This paper proposed a fusion method based on Extended Kalman Filter (EKF), which takes the InSAR-derived DEMs as states in prediction step and the flattened interferograms as observations in control step to generate the final fused DEM. Before the fusion, detection of layover and shadow regions, low-coherence regions and regions with large height error is carried out because MMIRs in these regions are believed to be unreliable and thereafter are excluded. The whole processing flow is tested with TerraSAR-X and Envisat ASAR datasets. Finally, the fused DEM is validated with ASTER GDEM and national standard DEM of China. The results demonstrate that the proposed method is effective even in low coherence areas.

Elevation Extraction and Deformation Monitoring by Multitemporal InSAR of Lupu Bridge in Shanghai

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Jingwen Zhao

2017-08-01

Full Text Available Monitoring, assessing, and understanding the structural health of large infrastructures, such as buildings, bridges, dams, tunnels, and highways, is important for urban development and management, as the gradual deterioration of such structures may result in catastrophic structural failure leading to high personal and economic losses. With a higher spatial resolution and a shorter revisit period, interferometric synthetic aperture radar (InSAR plays an increasing role in the deformation monitoring and height extraction of structures. As a focal point of the InSAR data processing chain, phase unwrapping has a direct impact on the accuracy of the results. In complex urban areas, large elevation differences between the top and bottom parts of a large structure combined with a long interferometric baseline can result in a serious phase-wrapping problem. Here, with no accurate digital surface model (DSM available, we handle the large phase gradients of arcs in multitemporal InSAR processing using a long–short baseline iteration method. Specifically, groups of interferometric pairs with short baselines are processed to obtain the rough initial elevation estimations of the persistent scatterers (PSs. The baseline threshold is then loosened in subsequent iterations to improve the accuracy of the elevation estimates step by step. The LLL lattice reduction algorithm (by Lenstra, Lenstra, and Lovász is applied in the InSAR phase unwrapping process to rapidly reduce the search radius, compress the search space, and improve the success rate in resolving the phase ambiguities. Once the elevations of the selected PSs are determined, they are used in the following two-dimensional phase regression involving both elevations and deformations. A case study of Lupu Bridge in Shanghai is carried out for the algorithm’s verification. The estimated PS elevations agree well (within 1 m with the official Lupu Bridge model data, while the PS deformation time series

Time-series analysis of surface deformation at Brady Hot Springs geothermal field (Nevada) using interferometric synthetic aperture radar

Energy Technology Data Exchange (ETDEWEB)

Ali, S. T. [Univ. of Wisconsin, Madison, WI (United States); Akerley, J. [Ormat Technologies Inc., Reno, NV (United States); Baluyut, E. C. [Univ. of Wisconsin, Madison, WI (United States); Cardiff, M. [Univ. of Wisconsin, Madison, WI (United States); Davatzes, N. C. [Temple Univ., Philadelphia, PA (United States). Dept. of Earth and Environmental Science; Feigl, K. L. [Univ. of Wisconsin, Madison, WI (United States); Foxall, W. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Fratta, D. [Univ. of Wisconsin, Madison, WI (United States); Mellors, R. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Spielman, P. [Ormat Technologies Inc., Reno, NV (United States); Wang, H. F. [Univ. of Wisconsin, Madison, WI (United States); Zemach, E. [Ormat Technologies Inc., Reno, NV (United States)

2016-05-01

We analyze interferometric synthetic aperture radar (InSAR) data acquired between 2004 and 2014, by the ERS-2, Envisat, ALOS and TerraSAR-X/TanDEM-X satellite missions to measure and characterize time-dependent deformation at the Brady Hot Springs geothermal field in western Nevada due to extraction of fluids. The long axis of the ~4 km by ~1.5 km elliptical subsiding area coincides with the strike of the dominant normal fault system at Brady. Within this bowl of subsidence, the interference pattern shows several smaller features with length scales of the order of ~1 km. This signature occurs consistently in all of the well-correlated interferometric pairs spanning several months. Results from inverse modeling suggest that the deformation is a result of volumetric contraction in shallow units, no deeper than 600 m, likely associated with damaged regions where fault segments mechanically interact. Such damaged zones are expected to extend downward along steeply dipping fault planes, providing a high permeability conduit to the production wells. Using time series analysis, we test the hypothesis that geothermal production drives the observed deformation. We find a good correlation between the observed deformation rate and the rate of production in the shallow wells. We also explore mechanisms that could potentially cause the observed deformation, including thermal contraction of rock, decline in pore pressure and dissolution of minerals over time.

Monitoring Volcano Deformation in the Northernmost Andes with ALOS InSAR Time-Series

Science.gov (United States)

Morales Rivera, A. M.; Amelung, F.

2014-12-01

Satellite-based Interferometric Synthetic Aperture Radar (InSAR) is well known to be used as a volcano monitoring tool, providing the opportunity to conduct local and regional surveys to detect and measure volcanic deformation. The signals detected by InSAR on volcanoes can be related to various phenomena, such as volume changes in magmatic reservoirs, compaction of recent deposits, changes in hydrothermal activity, and flank instability. The InSAR time-series method has well documented examples of these phenomena, including precursory inflation of magma reservoirs months prior to volcanic eruptions, proving its potential for early warning systems. We use the ALOS-1 satellite from the Japanese Aerospace Exploration Agency (JAXA), which acquired a global L-band data set of nearly 20 acquisitions during 2007-2011, to make an InSAR time-series analysis using the Small Baseline method (SBAS). Our analysis covers all of the volcanoes in Colombia, Ecuador, and Peru that are cataloged by the Global Volcanism Program. We present results showing time-dependent ground deformation on an near the volcanoes, and present kinematic models to constrain the characteristics of the magmatic sources for the cases in which the deformation is likely related to changes in magma reservoir pressurization.

InSAR Scientific Computing Environment

Science.gov (United States)

Rosen, Paul A.; Sacco, Gian Franco; Gurrola, Eric M.; Zabker, Howard A.

2011-01-01

This computing environment is the next generation of geodetic image processing technology for repeat-pass Interferometric Synthetic Aperture (InSAR) sensors, identified by the community as a needed capability to provide flexibility and extensibility in reducing measurements from radar satellites and aircraft to new geophysical products. This software allows users of interferometric radar data the flexibility to process from Level 0 to Level 4 products using a variety of algorithms and for a range of available sensors. There are many radar satellites in orbit today delivering to the science community data of unprecedented quantity and quality, making possible large-scale studies in climate research, natural hazards, and the Earth's ecosystem. The proposed DESDynI mission, now under consideration by NASA for launch later in this decade, would provide time series and multiimage measurements that permit 4D models of Earth surface processes so that, for example, climate-induced changes over time would become apparent and quantifiable. This advanced data processing technology, applied to a global data set such as from the proposed DESDynI mission, enables a new class of analyses at time and spatial scales unavailable using current approaches. This software implements an accurate, extensible, and modular processing system designed to realize the full potential of InSAR data from future missions such as the proposed DESDynI, existing radar satellite data, as well as data from the NASA UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar), and other airborne platforms. The processing approach has been re-thought in order to enable multi-scene analysis by adding new algorithms and data interfaces, to permit user-reconfigurable operation and extensibility, and to capitalize on codes already developed by NASA and the science community. The framework incorporates modern programming methods based on recent research, including object-oriented scripts controlling legacy and

InSAR detects increase in surface subsidence caused by an Arctic tundra fire

Science.gov (United States)

Liu, Lin; Jafarov, Elchin E.; Schaefer, Kevin M.; Jones, Benjamin M.; Zebker, Howard A.; Williams, Christopher A.; Rogan, John; Zhang, Tingjun

2014-01-01

Wildfire is a major disturbance in the Arctic tundra and boreal forests, having a significant impact on soil hydrology, carbon cycling, and permafrost dynamics. This study explores the use of the microwave Interferometric Synthetic Aperture Radar (InSAR) technique to map and quantify ground surface subsidence caused by the Anaktuvuk River fire on the North Slope of Alaska. We detected an increase of up to 8 cm of thaw-season ground subsidence after the fire, which is due to a combination of thickened active layer and permafrost thaw subsidence. Our results illustrate the effectiveness and potential of using InSAR to quantify fire impacts on the Arctic tundra, especially in regions underlain by ice-rich permafrost. Our study also suggests that surface subsidence is a more comprehensive indicator of fire impacts on ice-rich permafrost terrain than changes in active layer thickness alone.

Seamless Synthetic Aperture Radar Archive for Interferometry Analysis

Science.gov (United States)

Baker, S.; Baru, C.; Bryson, G.; Buechler, B.; Crosby, C.; Fielding, E.; Meertens, C.; Nicoll, J.; Youn, C.

2014-11-01

The NASA Advancing Collaborative Connections for Earth System Science (ACCESS) seamless synthetic aperture radar (SAR) archive (SSARA) project is a collaboration between UNAVCO, the Alaska Satellite Facility (ASF), the Jet Propulsion Laboratory (JPL), and OpenTopography at the San Diego Supercomputer Center (SDSC) to design and implement a seamless distributed access system for SAR data and derived interferometric SAR (InSAR) data products. A unified application programming interface (API) has been created to search the SAR archives at ASF and UNAVCO, 30 and 90-m SRTM DEM data available through OpenTopography, and tropospheric data from the NASA OSCAR project at JPL. The federated query service provides users a single access point to search for SAR granules, InSAR pairs, and corresponding DEM and tropospheric data products from the four archives, as well as the ability to search and download pre-processed InSAR products from ASF and UNAVCO.

Comparison of four moderate-size earthquakes in southern California using seismology and InSAR

Science.gov (United States)

Mellors, R.J.; Magistrale, H.; Earle, P.; Cogbill, A.H.

2004-01-01

Source parameters determined from interferometric synthetic aperture radar (InSAR) measurements and from seismic data are compared from four moderate-size (less than M 6) earthquakes in southern California. The goal is to verify approximate detection capabilities of InSAR, assess differences in the results, and test how the two results can be reconciled. First, we calculated the expected surface deformation from all earthquakes greater than magnitude 4 in areas with available InSAR data (347 events). A search for deformation from the events in the interferograms yielded four possible events with magnitudes less than 6. The search for deformation was based on a visual inspection as well as cross-correlation in two dimensions between the measured signal and the expected signal. A grid-search algorithm was then used to estimate focal mechanism and depth from the InSAR data. The results were compared with locations and focal mechanisms from published catalogs. An independent relocation using seismic data was also performed. The seismic locations fell within the area of the expected rupture zone for the three events that show clear surface deformation. Therefore, the technique shows the capability to resolve locations with high accuracy and is applicable worldwide. The depths determined by InSAR agree with well-constrained seismic locations determined in a 3D velocity model. Depth control for well-imaged shallow events using InSAR data is good, and better than the seismic constraints in some cases. A major difficulty for InSAR analysis is the poor temporal coverage of InSAR data, which may make it impossible to distinguish deformation due to different earthquakes at the same location.

Quantifying sub-pixel urban impervious surface through fusion of optical and inSAR imagery

Science.gov (United States)

Yang, L.; Jiang, L.; Lin, H.; Liao, M.

2009-01-01

In this study, we explored the potential to improve urban impervious surface modeling and mapping with the synergistic use of optical and Interferometric Synthetic Aperture Radar (InSAR) imagery. We used a Classification and Regression Tree (CART)-based approach to test the feasibility and accuracy of quantifying Impervious Surface Percentage (ISP) using four spectral bands of SPOT 5 high-resolution geometric (HRG) imagery and three parameters derived from the European Remote Sensing (ERS)-2 Single Look Complex (SLC) SAR image pair. Validated by an independent ISP reference dataset derived from the 33 cm-resolution digital aerial photographs, results show that the addition of InSAR data reduced the ISP modeling error rate from 15.5% to 12.9% and increased the correlation coefficient from 0.71 to 0.77. Spatially, the improvement is especially noted in areas of vacant land and bare ground, which were incorrectly mapped as urban impervious surfaces when using the optical remote sensing data. In addition, the accuracy of ISP prediction using InSAR images alone is only marginally less than that obtained by using SPOT imagery. The finding indicates the potential of using InSAR data for frequent monitoring of urban settings located in cloud-prone areas.

A Fast Multi-layer Subnetwork Connection Method for Time Series InSAR Technique

Directory of Open Access Journals (Sweden)

WU Hong'an

2016-10-01

Full Text Available Nowadays, times series interferometric synthetic aperture radar (InSAR technique has been widely used in ground deformation monitoring, especially in urban areas where lots of stable point targets can be detected. However, in standard time series InSAR technique, affected by atmospheric correlation distance and the threshold of linear model coherence, the Delaunay triangulation for connecting point targets can be easily separated into many discontinuous subnetworks. Thus it is difficult to retrieve ground deformation in non-urban areas. In order to monitor ground deformation in large areas efficiently, a novel multi-layer subnetwork connection (MLSC method is proposed for connecting all subnetworks. The advantage of the method is that it can quickly reduce the number of subnetworks with valid edges layer-by-layer. This method is compared with the existing complex network connecting mehod. The experimental results demonstrate that the data processing time of the proposed method is only 32.56% of the latter one.

Applicability of interferometric SAR technology to ground movement and pipeline monitoring

Science.gov (United States)

Grivas, Dimitri A.; Bhagvati, Chakravarthy; Schultz, B. C.; Trigg, Alan; Rizkalla, Moness

1998-03-01

This paper summarizes the findings of a cooperative effort between NOVA Gas Transmission Ltd. (NGTL), the Italian Natural Gas Transmission Company (SNAM), and Arista International, Inc., to determine whether current remote sensing technologies can be utilized to monitor small-scale ground movements over vast geographical areas. This topic is of interest due to the potential for small ground movements to cause strain accumulation in buried pipeline facilities. Ground movements are difficult to monitor continuously, but their cumulative effect over time can have a significant impact on the safety of buried pipelines. Interferometric synthetic aperture radar (InSAR or SARI) is identified as the most promising technique of those considered. InSAR analysis involves combining multiple images from consecutive passes of a radar imaging platform. The resulting composite image can detect changes as small as 2.5 to 5.0 centimeters (based on current analysis methods and radar satellite data of 5 centimeter wavelength). Research currently in progress shows potential for measuring ground movements as small as a few millimeters. Data needed for InSAR analysis is currently commercially available from four satellites, and additional satellites are planned for launch in the near future. A major conclusion of the present study is that InSAR technology is potentially useful for pipeline integrity monitoring. A pilot project is planned to test operational issues.

Comparison of elevation derived from insar data with dem from topography map in Son Dong, Bac Giang, Viet Nam

Science.gov (United States)

Nguyen, Duy

2012-07-01

Digital Elevation Models (DEMs) are used in many applications in the context of earth sciences such as in topographic mapping, environmental modeling, rainfall-runoff studies, landslide hazard zonation, seismic source modeling, etc. During the last years multitude of scientific applications of Synthetic Aperture Radar Interferometry (InSAR) techniques have evolved. It has been shown that InSAR is an established technique of generating high quality DEMs from space borne and airborne data, and that it has advantages over other methods for the generation of large area DEM. However, the processing of InSAR data is still a challenging task. This paper describes InSAR operational steps and processing chain for DEM generation from Single Look Complex (SLC) SAR data and compare a satellite SAR estimate of surface elevation with a digital elevation model (DEM) from Topography map. The operational steps are performed in three major stages: Data Search, Data Processing, and product Validation. The Data processing stage is further divided into five steps of Data Pre-Processing, Co-registration, Interferogram generation, Phase unwrapping, and Geocoding. The Data processing steps have been tested with ERS 1/2 data using Delft Object-oriented Interferometric (DORIS) InSAR processing software. Results of the outcome of the application of the described processing steps to real data set are presented.

UAVSAR and TerraSAR-X Based InSAR Detection of Localized Subsidence in the New Orleans Area

Science.gov (United States)

Blom, R. G.; An, K.; Jones, C. E.; Latini, D.

2014-12-01

Vulnerability of the US Gulf coast to inundation has received increased attention since hurricanes Katrina and Rita. Compounding effects of sea level rise, wetland loss, and regional and local subsidence makes flood protection a difficult challenge, and particularly for the New Orleans area. Key to flood protection is precise knowledge of elevations and elevation changes. Analysis of historical and continuing geodetic measurements show surprising complexity, including locations subsiding more rapidly than considered during planning of hurricane protection and coastal restoration projects. Combining traditional, precise geodetic data with interferometric synthetic aperture radar (InSAR) observations can provide geographically dense constraints on surface deformation. The Gulf Coast environment is challenging for InSAR techniques, especially with systems not designed for interferometry. We use two InSAR capable systems, the L- band (24 cm wavelength) airborne JPL/NASA UAVSAR, and the DLR/EADS Astrium spaceborne TerraSAR X-band (3 cm wavelength), and compare results. First, we are applying pair-wise InSAR to the longer wavelength UAVSAR data to detect localized elevation changes potentially impacting flood protection infrastructure from 2009 - 2014. We focus on areas on and near flood protection infrastructure to identify changes indicative of subsidence, structural deformation, and/or seepage. The Spaceborne TerraSAR X-band SAR system has relatively frequent observations, and dense persistent scatterers in urban areas, enabling measurement of very small displacements. We compare L-band UAVSAR results with permanent scatterer (PS-InSAR) and Short Baseline Subsets (SBAS) interferometric analyses of a stack composed by 28 TerraSAR X-band images acquired over the same period. Thus we can evaluate results from the different radar frequencies and analyses techniques. Preliminary results indicate subsidence features potentially of a variety of causes, including ground water

Analysis of Land Deformation on Slope Area using PS InSAR. Case Study: Malang Area

International Nuclear Information System (INIS)

Sudiana, Dodi; Rizkinia, Mia; Arief, Rahmat; Rokhmatuloh; Ardiansyah; Setiadi, Bambang; Bayuaji, Luhur; Sri Sumantyo, Josaphat Tetuko

2014-01-01

The geographical position of Indonesia located between two continents and oceans is strategic, but at large risk of experiencing various disasters. Climate change and vulnerable location (surrounded by plates and geological faults in the Earth's crust) creates an earthquake-prone region and causes land/mudslides. In this paper, PS InSAR method (Persistent Scatterer Interferometric Synthetic Aperture Radar) is implemented to Phased Array type L-band Synthetic Aperture Radar (PALSAR) data to study the potential damage caused by the earthquake or volcanic eruption in Malang vicinity. By comparing the amplitude images periodically, shifting soil can be determined using precise orbital information. The analysis showed a significant decrease of land deformation on slope area in Klojen district in Malang city, reached up to −7.128 mm/year

The Development and Delivery of On-Demand RADARSAT Constellation Mission Ground Deformation Products Based on Advanced Insar Technology

Science.gov (United States)

Samsonov, S. V.; Feng, W.

2017-12-01

InSAR-based mapping of surface deformation (displacement) has proven valuable to a variety of geoscience applications within NRCan. Conventional approaches to InSAR analysis require significant expert intervention to separate useful signal from noise and are not suited to the address the opportunities and challenges presented by the large multi-temporal SAR datasets provided by future radar constellations. The Canada Centre for Mapping and Earth Observation (CCMEO) develops, in support of NRCAN and Government of Canada priorities a framework for automatic generation of standard and advanced deformation products based on Interferometric Synthetic Aperture Radar (InSAR) technology from RADARSAT Constellation Mission (RCM) Synthetic Aperture Radar data. We utilize existing processing algorithms that are currently used for processing RADARSAT-2 data and adapt them to RCM specifications. In addition we develop novel advanced processing algorithms that address large data sets made possible by the satellites' rapid revisit cycle and expand InSAR functionality to regional and national scales across a wide range of time scales. Through automation the system makes it possible to extend the mapping of surface deformation to non-SAR experts. The architecture is scalable and expandable to serve large number of clients and simultaneously address multiple application areas including: natural and anthropogenic hazards, natural resource development, permafrost and glacier monitoring, coastal and environmental change and wetlands mapping.

Answering the right question - integration of InSAR with other datasets

Science.gov (United States)

Holley, Rachel; McCormack, Harry; Burren, Richard

2014-05-01

The capabilities of satellite Interferometric Synthetic Aperture Radar (InSAR) are well known, and utilized across a wide range of academic and commercial applications. However there is a tendency, particularly in commercial applications, for users to ask 'What can we study with InSAR?'. When establishing a new technique this approach is important, but InSAR has been possible for 20 years now and, even accounting for new and innovative algorithms, this ground has been thoroughly explored. Too many studies conclude 'We show the ground is moving here, by this much', and mention the wider context as an afterthought. The focus needs to shift towards first asking the right questions - in fields as diverse as hazard awareness, resource optimization, financial considerations and pure scientific enquiry - and then working out how to achieve the best possible answers. Depending on the question, InSAR (and ground deformation more generally) may provide a large or small contribution to the overall solution, and there are usually benefits to integrating a number of techniques to capitalize on the complementary capabilities and provide the most useful measurements. However, there is still a gap between measurements and answers, and unlocking the value of the data relies heavily on appropriate visualization, integrated analysis, communication between technique and application experts, and appropriate use of modelling. We present a number of application examples, and demonstrate how their usefulness can be transformed by moving from a focus on data to answers - integrating complementary geodetic, geophysical and geological datasets and geophysical modeling with appropriate visualization, to enable comprehensive solution-focused interpretation. It will also discuss how forthcoming developments are likely to further advance realisation of the full potential satellite InSAR holds.

Simplex GPS and InSAR Inversion Software

Science.gov (United States)

Donnellan, Andrea; Parker, Jay W.; Lyzenga, Gregory A.; Pierce, Marlon E.

2012-01-01

Changes in the shape of the Earth's surface can be routinely measured with precisions better than centimeters. Processes below the surface often drive these changes and as a result, investigators require models with inversion methods to characterize the sources. Simplex inverts any combination of GPS (global positioning system), UAVSAR (uninhabited aerial vehicle synthetic aperture radar), and InSAR (interferometric synthetic aperture radar) data simultaneously for elastic response from fault and fluid motions. It can be used to solve for multiple faults and parameters, all of which can be specified or allowed to vary. The software can be used to study long-term tectonic motions and the faults responsible for those motions, or can be used to invert for co-seismic slip from earthquakes. Solutions involving estimation of fault motion and changes in fluid reservoirs such as magma or water are possible. Any arbitrary number of faults or parameters can be considered. Simplex specifically solves for any of location, geometry, fault slip, and expansion/contraction of a single or multiple faults. It inverts GPS and InSAR data for elastic dislocations in a half-space. Slip parameters include strike slip, dip slip, and tensile dislocations. It includes a map interface for both setting up the models and viewing the results. Results, including faults, and observed, computed, and residual displacements, are output in text format, a map interface, and can be exported to KML. The software interfaces with the QuakeTables database allowing a user to select existing fault parameters or data. Simplex can be accessed through the QuakeSim portal graphical user interface or run from a UNIX command line.

Integrated analysis of PALSAR/Radarsat-1 InSAR and ENVISAT altimeter data for mapping of absolute water level changes in Louisiana wetlands

Science.gov (United States)

Kim, J.-W.; Lu, Z.; Lee, H.; Shum, C.K.; Swarzenski, C.M.; Doyle, T.W.; Baek, S.-H.

2009-01-01

Interferometric Synthetic Aperture Radar (InSAR) has been used to detect relative water level changes in wetlands. We developed an innovative method to integrate InSAR and satellite radar altimetry for measuring absolute or geocentric water level changes and applied the methodology to remote areas of swamp forest in coastal Louisiana. Coherence analysis of InSAR pairs suggested that the HH polarization is preferred for this type of observation, and polarimetric analysis can help to identify double-bounce backscattering areas in the wetland. ENVISAT radar altimeter-measured 18-Hz (along-track sampling of 417 m) water level data processed with regional stackfile method have been used to provide vertical references for water bodies separated by levees. The high-resolution (~ 40 m) relative water changes measured from ALOS PALSAR L-band and Radarsat-1 C-band InSAR are then integrated with ENVISAT radar altimetry to obtain absolute water level. The resulting water level time series were validated with in situ gauge observations within the swamp forest. We anticipate that this new technique will allow retrospective reconstruction and concurrent monitoring of water conditions and flow dynamics in wetlands, especially those lacking gauge networks.

Model Accuracy Comparison for High Resolution Insar Coherence Statistics Over Urban Areas

Science.gov (United States)

Zhang, Yue; Fu, Kun; Sun, Xian; Xu, Guangluan; Wang, Hongqi

2016-06-01

The interferometric coherence map derived from the cross-correlation of two complex registered synthetic aperture radar (SAR) images is the reflection of imaged targets. In many applications, it can act as an independent information source, or give additional information complementary to the intensity image. Specially, the statistical properties of the coherence are of great importance in land cover classification, segmentation and change detection. However, compared to the amount of work on the statistical characters of SAR intensity, there are quite fewer researches on interferometric SAR (InSAR) coherence statistics. And to our knowledge, all of the existing work that focuses on InSAR coherence statistics, models the coherence with Gaussian distribution with no discrimination on data resolutions or scene types. But the properties of coherence may be different for different data resolutions and scene types. In this paper, we investigate on the coherence statistics for high resolution data over urban areas, by making a comparison of the accuracy of several typical statistical models. Four typical land classes including buildings, trees, shadow and roads are selected as the representatives of urban areas. Firstly, several regions are selected from the coherence map manually and labelled with their corresponding classes respectively. Then we try to model the statistics of the pixel coherence for each type of region, with different models including Gaussian, Rayleigh, Weibull, Beta and Nakagami. Finally, we evaluate the model accuracy for each type of region. The experiments on TanDEM-X data show that the Beta model has a better performance than other distributions.

MODEL ACCURACY COMPARISON FOR HIGH RESOLUTION INSAR COHERENCE STATISTICS OVER URBAN AREAS

Directory of Open Access Journals (Sweden)

Y. Zhang

2016-06-01

Full Text Available The interferometric coherence map derived from the cross-correlation of two complex registered synthetic aperture radar (SAR images is the reflection of imaged targets. In many applications, it can act as an independent information source, or give additional information complementary to the intensity image. Specially, the statistical properties of the coherence are of great importance in land cover classification, segmentation and change detection. However, compared to the amount of work on the statistical characters of SAR intensity, there are quite fewer researches on interferometric SAR (InSAR coherence statistics. And to our knowledge, all of the existing work that focuses on InSAR coherence statistics, models the coherence with Gaussian distribution with no discrimination on data resolutions or scene types. But the properties of coherence may be different for different data resolutions and scene types. In this paper, we investigate on the coherence statistics for high resolution data over urban areas, by making a comparison of the accuracy of several typical statistical models. Four typical land classes including buildings, trees, shadow and roads are selected as the representatives of urban areas. Firstly, several regions are selected from the coherence map manually and labelled with their corresponding classes respectively. Then we try to model the statistics of the pixel coherence for each type of region, with different models including Gaussian, Rayleigh, Weibull, Beta and Nakagami. Finally, we evaluate the model accuracy for each type of region. The experiments on TanDEM-X data show that the Beta model has a better performance than other distributions.

Block-like plate movements in eastern Anatolia observed by InSAR

KAUST Repository

Cavalie, Olivier

2014-01-16

The question whether continental plates deform internally or move as rigid blocks has been debated for several decades. To further address this question, we use large-scale interferometric synthetic aperture radar (InSAR) data sets to study how eastern Anatolia and its surrounding plates deform. We find that most of the deformation is focused at the North and East Anatolian faults and little intraplate deformation takes place. Anatolia is therefore moving, at least its eastern part, as a uniform block. We estimate the slip velocity and locking depth of the North Anatolian fault at this location to be 20 mm/yr and ~14 km, respectively. High deformation gradient found near the East Anatolian fault, on the other hand, suggests that little stress is accumulating along the eastern sections of that fault.

Improving InSAR geodesy using Global Atmospheric Models

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Jolivet, Romain; Agram, Piyush Shanker; Lin, Nina Y.; Simons, Mark; Doin, Marie-Pierre; Peltzer, Gilles; Li, Zhenghong

2014-03-01

Spatial and temporal variations of pressure, temperature, and water vapor content in the atmosphere introduce significant confounding delays in interferometric synthetic aperture radar (InSAR) observations of ground deformation and bias estimates of regional strain rates. Producing robust estimates of tropospheric delays remains one of the key challenges in increasing the accuracy of ground deformation measurements using InSAR. Recent studies revealed the efficiency of global atmospheric reanalysis to mitigate the impact of tropospheric delays, motivating further exploration of their potential. Here we explore the effectiveness of these models in several geographic and tectonic settings on both single interferograms and time series analysis products. Both hydrostatic and wet contributions to the phase delay are important to account for. We validate these path delay corrections by comparing with estimates of vertically integrated atmospheric water vapor content derived from the passive multispectral imager Medium-Resolution Imaging Spectrometer, onboard the Envisat satellite. Generally, the performance of the prediction depends on the vigor of atmospheric turbulence. We discuss (1) how separating atmospheric and orbital contributions allows one to better measure long-wavelength deformation and (2) how atmospheric delays affect measurements of surface deformation following earthquakes, and (3) how such a method allows us to reduce biases in multiyear strain rate estimates by reducing the influence of unevenly sampled seasonal oscillations of the tropospheric delay.

Advanced Corrections for InSAR Using GPS and Numerical Weather Models

Science.gov (United States)

Cossu, F.; Foster, J. H.; Amelung, F.; Varugu, B. K.; Businger, S.; Cherubini, T.

2017-12-01

We present results from an investigation into the application of numerical weather models for generating tropospheric correction fields for Interferometric Synthetic Aperture Radar (InSAR). We apply the technique to data acquired from a UAVSAR campaign as well as from the CosmoSkyMed satellites. The complex spatial and temporal changes in the atmospheric propagation delay of the radar signal remain the single biggest factor limiting InSAR's potential for hazard monitoring and mitigation. A new generation of InSAR systems is being built and launched, and optimizing the science and hazard applications of these systems requires advanced methodologies to mitigate tropospheric noise. We use the Weather Research and Forecasting (WRF) model to generate a 900 m spatial resolution atmospheric models covering the Big Island of Hawaii and an even higher, 300 m resolution grid over the Mauna Loa and Kilauea volcanoes. By comparing a range of approaches, from the simplest, using reanalyses based on typically available meteorological observations, through to the "kitchen-sink" approach of assimilating all relevant data sets into our custom analyses, we examine the impact of the additional data sets on the atmospheric models and their effectiveness in correcting InSAR data. We focus particularly on the assimilation of information from the more than 60 GPS sites in the island. We ingest zenith tropospheric delay estimates from these sites directly into the WRF analyses, and also perform double-difference tomography using the phase residuals from the GPS processing to robustly incorporate heterogeneous information from the GPS data into the atmospheric models. We assess our performance through comparisons of our atmospheric models with external observations not ingested into the model, and through the effectiveness of the derived phase screens in reducing InSAR variance. Comparison of the InSAR data, our atmospheric analyses, and assessments of the active local and mesoscale

Remote Monitoring of Groundwater Overdraft Using GRACE and InSAR

Science.gov (United States)

Scher, C.; Saah, D.

2017-12-01

Gravity Recovery and Climate Experiment (GRACE) data paired with radar-derived analyses of volumetric changes in aquifer storage capacity present a viable technique for remote monitoring of aquifer depletion. Interferometric Synthetic Aperture Radar (InSAR) analyses of ground level subsidence can account for a significant portion of mass loss observed in GRACE data and provide information on point-sources of overdraft. This study summed one water-year of GRACE monthly mass change grids and delineated regions with negative water storage anomalies for further InSAR analyses. Magnitude of water-storage anomalies observed by GRACE were compared to InSAR-derived minimum volumetric changes in aquifer storage capacity as a result of measurable compaction at the surface. Four major aquifers were selected within regions where GRACE observed a net decrease in water storage (Central Valley, California; Mekong Delta, Vietnam; West Bank, occupied Palestinian Territory; and the Indus Basin, South Asia). Interferogram imagery of the extent and magnitude of subsidence within study regions provided estimates for net minimum volume of groundwater extracted between image acquisitions. These volumetric estimates were compared to GRACE mass change grids to resolve a percent contribution of mass change observed by GRACE likely due to groundwater overdraft. Interferograms revealed characteristic cones of depression within regions of net mass loss observed by GRACE, suggesting point-source locations of groundwater overdraft and demonstrating forensic potential for the use of InSAR and GRACE data in remote monitoring of aquifer depletion. Paired GRACE and InSAR analyses offer a technique to increase the spatial and temporal resolution of remote applications for monitoring groundwater overdraft in addition to providing a novel parameter - measurable vertical deformation at the surface - to global groundwater models.

Stochastic modeling for time series InSAR: with emphasis on atmospheric effects

Science.gov (United States)

Cao, Yunmeng; Li, Zhiwei; Wei, Jianchao; Hu, Jun; Duan, Meng; Feng, Guangcai

2018-02-01

Despite the many applications of time series interferometric synthetic aperture radar (TS-InSAR) techniques in geophysical problems, error analysis and assessment have been largely overlooked. Tropospheric propagation error is still the dominant error source of InSAR observations. However, the spatiotemporal variation of atmospheric effects is seldom considered in the present standard TS-InSAR techniques, such as persistent scatterer interferometry and small baseline subset interferometry. The failure to consider the stochastic properties of atmospheric effects not only affects the accuracy of the estimators, but also makes it difficult to assess the uncertainty of the final geophysical results. To address this issue, this paper proposes a network-based variance-covariance estimation method to model the spatiotemporal variation of tropospheric signals, and to estimate the temporal variance-covariance matrix of TS-InSAR observations. The constructed stochastic model is then incorporated into the TS-InSAR estimators both for parameters (e.g., deformation velocity, topography residual) estimation and uncertainty assessment. It is an incremental and positive improvement to the traditional weighted least squares methods to solve the multitemporal InSAR time series. The performance of the proposed method is validated by using both simulated and real datasets.

Evidence of rock slope breathing using ground-based InSAR

Science.gov (United States)

Rouyet, Line; Kristensen, Lene; Derron, Marc-Henri; Michoud, Clément; Blikra, Lars Harald; Jaboyedoff, Michel; Lauknes, Tom Rune

2017-07-01

Ground-Based Interferometric Synthetic Aperture Radar (GB-InSAR) campaigns were performed in summer 2011 and 2012 in the Romsdalen valley (Møre & Romsdal county, western Norway) in order to assess displacements on Mannen/Børa rock slope. Located 1 km northwest, a second GB-InSAR system continuously monitors the large Mannen rockslide. The availability of two GB-InSAR positions creates a wide coverage of the rock slope, including a slight dataset overlap valuable for validation. A phenomenon of rock slope breathing is detected in a remote and hard-to-access area in mid-slope. Millimetric upward displacements are recorded in August 2011. Analysis of 2012 GB-InSAR campaign, combined with the large dataset from the continuous station, shows that the slope is affected by inflation/deflation phenomenon between 5 and 10 mm along the line-of-sight. The pattern is not homogenous in time and inversions of movement have a seasonal recurrence. These seasonal changes are confirmed by satellite InSAR observations and can possibly be caused by hydrogeological variations. In addition, combination of GB-InSAR results, in situ measurements and satellite InSAR analyses contributes to a better overview of movement distribution over the whole area.

An airborne interferometric SAR system for high-performance 3D mapping

Science.gov (United States)

Lange, Martin; Gill, Paul

2009-05-01

With a vertical accuracy better than 1 m and collection rates up to 7000 km2/h, airborne interferometric synthetic aperture radars (InSAR) bridge the gap between space borne radar sensors and airborne optical LIDARs. This paper presents the latest generation of X-band InSAR sensors, developed by Intermap TechnologiesTM, which are operated on our four aircrafts. The sensors collect data for the NEXTMap(R) program - a digital elevation model (DEM) with 1 m vertical accuracy for the contiguous U.S., Hawaii, and most of Western Europe. For a successful operation, challenges like reduction of multipath reflections, very high interferometric phase stability, and a precise system calibration had to be mastered. Recent advances in sensor design, comprehensive system automation and diagnostics have increased the sensor reliability to a level where no radar operator is required onboard. Advanced flight planning significantly improved aircraft utilization and acquisition throughput, while reducing operational costs. Highly efficient data acquisition with straight flight lines up to 1200 km is daily routine meanwhile. The collected data pass though our automated processing cluster and finally are edited to our terrain model products. Extensive and rigorous quality control at every step of the workflow are key to maintain stable vertical accuracies of 1 m and horizontal accuracies of 2 m for our 3D maps. The combination of technical and operational advances presented in this paper enabled Intermap to survey two continents, producing 11 million km2 of uniform and accurate 3D terrain data.

Advanced InSAR imaging for dune mapping

Science.gov (United States)

Havivi, Shiran; August, Yitzhak; Blumberg, Dan G.; Rotman, Stanley R.

2015-04-01

Aeolian morphologies are formed in the presence of sufficient wind energy and available particles. These processes occur naturally or are further enhanced or reduced by human intervention. The dimensions of change are dependent primarily on the wind energy and surface properties. Since the 1970's, remote sensing imagery both optical and radar, are used for documentation and interpretation of the geomorphologic changes of sand dunes. Remote sensing studies of Aeolian morphologies is mostly useful to document major changes, yet, subtle changes, occurring in a period of days or months in scales of centimeters, are very difficult to detect in imagery. Interferometric Synthetic Aperture Radar (InSAR) is an imaging technique for measuring Earth's surface topography and deformation. InSAR images are produced by measuring the radar phase difference between two separated antennas that view the same surface area. Classical InSAR is based on high coherence between two images or more. The output (interferogram) can show subtle changes with an accuracy of several millimeters to centimeters. Very little work has been done on measuring or identifying the changes in dunes using InSAR. The reason is that dunes tend to be less coherent than firm, stable, surfaces. This research aims to demonstrate how interferometric decorrelation, or, coherence change detection, can be used for identifying dune instability. We hypothesize and demonstrate that the loss of radar coherence over time on dunes can be used as an indication of the dune's instability. When SAR images are acquired at sufficiently close intervals one can measure the time it takes to lose coherence and associate this time with geomorphic stability. To achieve our goals, the Nitzanim coastal dunes along the Mediterranean, 40 km south of Tel-Aviv, Israel, were chosen as a case study. The dunes in this area are of varying levels of stability and vegetation cover and have been monitored meteorologically, geomorphologically and

Application of InSAR and gravimetric surveys for developing construction codes in zones of land subsidence induced by groundwater extraction: case study of Aguascalientes, Mexico

Directory of Open Access Journals (Sweden)

J. Pacheco-Martínez

2015-11-01

Full Text Available Interferometric Synthetic Aperture Radar (InSAR has become a valuable tool for surface deformation monitoring, including land subsidence associated with groundwater extraction. Another useful tools for studying Earth's surface processes are geophysical methods such as Gravimetry. In this work we present the application of InSAR analysis and gravimetric surveying to generate valuable information for risk management related to land subsidence and surface faulting. Subsidence of the city of Aguascalientes, Mexico is presented as study case. Aguascalientes local governments have addressed land subsidence issues by including new requirements for new constructions projects in the State Urban Construction Code. Nevertheless, the resulting zoning proposed in the code is still subjective and not clearly defined. Our work based on gravimetric and InSAR surveys is aimed for improving the subsidence hazard zoning proposed in the State Urban Code in a more comprehensive way. The study includes a 2007–2011 ALOS InSAR time-series analysis of the Aguascalientes valley, an interpretation of the compete Bouguer gravimetric anomaly of the Aguascalientes urban area, and the application of time series and gravimetric anomaly maps for improve the subsidence hazard zoning of Aguascalientes City.

Crustal Deformation along San Andreas Fault System revealed by GPS and Sentinel-1 InSAR

Science.gov (United States)

Xu, X.; Sandwell, D. T.

2017-12-01

We present a crustal deformation velocity map along the San Andreas Fault System by combining measurements from Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) velocity models (CGM V1). We assembled 5 tracks of descending Sentinel-1 InSAR data spanning 2014.11-2017.02, and produced 545 interferograms, each of which covers roughly 250km x 420km area ( 60 bursts). These interferograms are unwrapped using SNAPHU [Chen & Zebker, 2002], with the 2Npi unwrapping ambiguity corrected with a sparse recovery method. We used coherence-based small baseline subset (SBAS) method [Tong & Schmidt, 2016] together with atmospheric correction by common-point stacking [Tymofyeyeva and Fialko, 2015] to construct deformation time series [Xu et. al., 2017]. Then we project the horizontal GPS model and vertical GPS data into satellite line-of-sight directions separately. We first remove the horizontal GPS model from InSAR measurements and perform elevation-dependent atmospheric phase correction. Then we compute the discrepancy between the remaining InSAR measurements and vertical GPS data. We interpolate this discrepancy and remove it from the residual InSAR measurements. Finally, we restore the horizontal GPS model. Preliminary results show that fault creep over the San Jacinto fault, the Elsinore fault, and the San Andreas creeping section is clearly resolved. During the period of drought, the Central Valley of California was subsiding at a high rate (up to 40 cm/yr), while the city of San Jose is uplifting due to recharge, with a quaternary fault acting as a ground water barrier. These findings will be reported during the meeting.

Correcting atmospheric effects on InSAR with MERIS water vapour data and elevation-dependent interpolation model

KAUST Repository

Li, Z. W.; Xu, Wenbin; Feng, G. C.; Hu, J.; Wang, C. C.; Ding, X. L.; Zhu, J. J.

2012-01-01

The propagation delay when radar signals travel from the troposphere has been one of the major limitations for the applications of high precision repeat-pass Interferometric Synthetic Aperture Radar (InSAR). In this paper, we first present an elevation-dependent atmospheric correction model for Advanced Synthetic Aperture Radar (ASAR—the instrument aboard the ENVISAT satellite) interferograms with Medium Resolution Imaging Spectrometer (MERIS) integrated water vapour (IWV) data. Then, using four ASAR interferometric pairs over Southern California as examples, we conduct the atmospheric correction experiments with cloud-free MERIS IWV data. The results show that after the correction the rms differences between InSAR and GPS have reduced by 69.6 per cent, 29 per cent, 31.8 per cent and 23.3 per cent, respectively for the four selected interferograms, with an average improvement of 38.4 per cent. Most importantly, after the correction, six distinct deformation areas have been identified, that is, Long Beach–Santa Ana Basin, Pomona–Ontario, San Bernardino and Elsinore basin, with the deformation velocities along the radar line-of-sight (LOS) direction ranging from −20 mm yr−1 to −30 mm yr−1 and on average around −25 mm yr−1, and Santa Fe Springs and Wilmington, with a slightly low deformation rate of about −10 mm yr−1 along LOS. Finally, through the method of stacking, we generate a mean deformation velocity map of Los Angeles over a period of 5 yr. The deformation is quite consistent with the historical deformation of the area. Thus, using the cloud-free MERIS IWV data correcting synchronized ASAR interferograms can significantly reduce the atmospheric effects in the interferograms and further better capture the ground deformation and other geophysical signals.

Correcting atmospheric effects on InSAR with MERIS water vapour data and elevation-dependent interpolation model

KAUST Repository

Li, Z. W.

2012-05-01

The propagation delay when radar signals travel from the troposphere has been one of the major limitations for the applications of high precision repeat-pass Interferometric Synthetic Aperture Radar (InSAR). In this paper, we first present an elevation-dependent atmospheric correction model for Advanced Synthetic Aperture Radar (ASAR—the instrument aboard the ENVISAT satellite) interferograms with Medium Resolution Imaging Spectrometer (MERIS) integrated water vapour (IWV) data. Then, using four ASAR interferometric pairs over Southern California as examples, we conduct the atmospheric correction experiments with cloud-free MERIS IWV data. The results show that after the correction the rms differences between InSAR and GPS have reduced by 69.6 per cent, 29 per cent, 31.8 per cent and 23.3 per cent, respectively for the four selected interferograms, with an average improvement of 38.4 per cent. Most importantly, after the correction, six distinct deformation areas have been identified, that is, Long Beach–Santa Ana Basin, Pomona–Ontario, San Bernardino and Elsinore basin, with the deformation velocities along the radar line-of-sight (LOS) direction ranging from −20 mm yr−1 to −30 mm yr−1 and on average around −25 mm yr−1, and Santa Fe Springs and Wilmington, with a slightly low deformation rate of about −10 mm yr−1 along LOS. Finally, through the method of stacking, we generate a mean deformation velocity map of Los Angeles over a period of 5 yr. The deformation is quite consistent with the historical deformation of the area. Thus, using the cloud-free MERIS IWV data correcting synchronized ASAR interferograms can significantly reduce the atmospheric effects in the interferograms and further better capture the ground deformation and other geophysical signals.

A Constellation of CubeSat InSAR Sensors for Rapid-Revisit Surface Deformation Studies

Science.gov (United States)

Wye, L.; Lee, S.; Yun, S. H.; Zebker, H. A.; Stock, J. D.; Wicks, C. W., Jr.; Doe, R.

2016-12-01

The 2007 NRC Decadal Survey for Earth Sciences highlights three major Earth surface deformation themes: 1) solid-earth hazards and dynamics; 2) human health and security; and 3) land-use change, ecosystem dynamics and biodiversity. Space-based interferometric synthetic aperture radar (InSAR) is a key change detection tool for addressing these themes. Here, we describe the mission and radar payload design for a constellation of S-band InSAR sensors specifically designed to provide the global, high temporal resolution, sub-cm level deformation accuracy needed to address some of the major Earth system goals. InSAR observations with high temporal resolution are needed to properly monitor certain nonlinearly time-varying features (e.g., unstable volcanoes, active fault lines, and heavily-used groundwater or hydrocarbon reservoirs). Good temporal coverage is also needed to reduce atmospheric artifacts by allowing multiple acquisitions to be averaged together, since each individual SAR measurement is corrupted by up to several cm of atmospheric noise. A single InSAR platform is limited in how often it can observe a given scene without sacrificing global spatial coverage. Multiple InSAR platforms provide the spatial-temporal flexibility required to maximize the science return. However, building and launching multiple InSAR platforms is cost-prohibitive for traditional satellites. SRI International (SRI) and our collaborators are working to exploit developments in nanosatellite technology, in particular the emergence of the CubeSat standard, to provide high-cadence InSAR capabilities in an affordable package. The CubeSat Imaging Radar for Earth Science (CIRES) subsystem, a prototype SAR elec­tronics package developed by SRI with support from a 2014 NASA ESTO ACT award, is specifically scaled to be a drop-in radar solution for resource-limited delivery systems like CubeSats and small airborne vehicles. Here, we present our mission concept and flow-down requirements for a

Remote Sensing of Deformation of a High Concrete-Faced Rockfill Dam Using InSAR: A Study of the Shuibuya Dam, China

Directory of Open Access Journals (Sweden)

Wei Zhou

2016-03-01

Full Text Available Settlement is one of the most important deformation characteristics of high concrete faced rockfill dams (CFRDs, >100 m. High CFRDs safety would pose a great threat to the security of people’s lives and property downstream if this kind of deformation were not to be measured correctly, as traditional monitoring approaches have limitations in terms of durability, coverage, and efficiency. It has become urgent to develop new monitoring techniques to complement or replace traditional monitoring approaches for monitoring the safety and operation status of high CFRDs. This study examines the Shuibuya Dam (up to 233.5 m in height in China, which is currently the highest CFRD in the world. We used space-borne Interferometric Synthetic Aperture Radar (InSAR time series to monitor the surface deformation of the Shuibuya Dam. Twenty-one ALOS PALSAR images that span the period from 28 February 2007 to 11 March 2011 were used to map the spatial and temporal deformation of the dam. A high correlation of 0.93 between the InSAR and the in-situ monitoring results confirmed the reliability of the InSAR method; the deformation history derived from InSAR is also consistent with the in-situ settlement monitoring system. In addition, the InSAR results allow continuous investigation of dam deformation over a wide area that includes the entire dam surface as well as the surrounding area, offering a clear picture continuously of the dam deformation.

The influence on the interferometry due to the instability of ground-based synthetic aperture radar work platform

Science.gov (United States)

Tao, Gang; Wei, Guohua; Wang, Xu; Kong, Ming

2018-03-01

There has been increased interest over several decades for applying ground-based synthetic aperture radar (GB-SAR) for monitoring terrain displacement. GB-SAR can achieve multitemporal surface deformation maps of the entire terrain with high spatial resolution and submilimetric accuracy due to the ability of continuous monitoring a certain area day and night regardless of the weather condition. The accuracy of the interferometric measurement result is very important. In this paper, the basic principle of InSAR is expounded, the influence of the platform's instability on the interferometric measurement results are analyzed. The error sources of deformation detection estimation are analyzed using precise geometry of imaging model. Finally, simulation results demonstrates the validity of our analysis.

Shortcomings of InSAR for studying megathrust earthquakes: The case of the M w 9.0 Tohoku-Oki earthquake

KAUST Repository

Feng, Guangcai

2012-05-28

Interferometric Synthetic Aperture Radar (InSAR) observations are sometimes the only geodetic data of large subduction-zone earthquakes. However, these data usually suffer from spatially long-wavelength orbital and atmospheric errors that can be difficult to distinguish from the coseismic deformation and may therefore result in biased fault-slip inversions. To study how well InSAR constrains fault-slip of large subduction zone earthquakes, we use data of the 11 March 2011 Tohoku-Oki earthquake (Mw9.0) and test InSAR-derived fault-slip models against models constrained by GPS data from the extensive nationwide network in Japan. The coseismic deformation field was mapped using InSAR data acquired from multiple ascending and descending passes of the ALOS and Envisat satellites. We then estimated several fault-slip distribution models that were constrained using the InSAR data alone, onland and seafloor GPS/acoustic data, or combinations of the different data sets. Based on comparisons of the slip models, we find that there is no real gain by including InSAR observations for determining the fault slip distribution of this earthquake. That said, however, some of the main fault-slip patterns can be retrieved using the InSAR data alone when estimating long wavelength orbital/atmospheric ramps as a part of the modeling. Our final preferred fault-slip solution of the Tohoku-Oki earthquake is based only on the GPS data and has maximum reverse- and strike-slip of 36.0 m and 6.0 m, respectively, located northeast of the epicenter at a depth of 6 km, and has a total geodetic moment is 3.6 × 1022 Nm (Mw 9.01), similar to seismological estimates.

Block adjustment of airborne InSAR based on interferogram phase and POS data

Science.gov (United States)

Yue, Xijuan; Zhao, Yinghui; Han, Chunming; Dou, Changyong

2015-12-01

High-precision surface elevation information in large scale can be obtained efficiently by airborne Interferomatric Synthetic Aperture Radar (InSAR) system, which is recently becoming an important tool to acquire remote sensing data and perform mapping applications in the area where surveying and mapping is difficult to be accomplished by spaceborne satellite or field working. . Based on the study of the three-dimensional (3D) positioning model using interferogram phase and Position and Orientation System (POS) data and block adjustment error model, a block adjustment method to produce seamless wide-area mosaic product generated from airborne InSAR data is proposed in this paper. The effect of 6 parameters, including trajectory and attitude of the aircraft, baseline length and incline angle, slant range, and interferometric phase, on the 3D positioning accuracy is quantitatively analyzed. Using the data acquired in the field campaign conducted in Mianyang county Sichuan province, China in June 2011, a mosaic seamless Digital Elevation Model (DEM) product was generated from 76 images in 4 flight strips by the proposed block adjustment model. The residuals of ground control points (GCPs), the absolute positioning accuracy of check points (CPs) and the relative positioning accuracy of tie points (TPs) both in same and adjacent strips were assessed. The experimental results suggest that the DEM and Digital Orthophoto Map (DOM) product generated by the airborne InSAR data with sparse GCPs can meet mapping accuracy requirement at scale of 1:10 000.

A novel multitemporal insar model for joint estimation of deformation rates and orbital errors

KAUST Repository

Zhang, Lei

2014-06-01

Orbital errors, characterized typically as longwavelength artifacts, commonly exist in interferometric synthetic aperture radar (InSAR) imagery as a result of inaccurate determination of the sensor state vector. Orbital errors degrade the precision of multitemporal InSAR products (i.e., ground deformation). Although research on orbital error reduction has been ongoing for nearly two decades and several algorithms for reducing the effect of the errors are already in existence, the errors cannot always be corrected efficiently and reliably. We propose a novel model that is able to jointly estimate deformation rates and orbital errors based on the different spatialoral characteristics of the two types of signals. The proposed model is able to isolate a long-wavelength ground motion signal from the orbital error even when the two types of signals exhibit similar spatial patterns. The proposed algorithm is efficient and requires no ground control points. In addition, the method is built upon wrapped phases of interferograms, eliminating the need of phase unwrapping. The performance of the proposed model is validated using both simulated and real data sets. The demo codes of the proposed model are also provided for reference. © 2013 IEEE.

ATMOSPHERIC PHASE DELAY CORRECTION OF D-INSAR BASED ON SENTINEL-1A

Directory of Open Access Journals (Sweden)

X. Li

2018-04-01

Full Text Available In this paper, we used the Generic Atmospheric Correction Online Service for InSAR (GACOS tropospheric delay maps to correct the atmospheric phase delay of the differential interferometric synthetic aperture radar (D-InSAR monitoring, and we improved the accuracy of subsidence monitoring using D-InSAR technology. Atmospheric phase delay, as one of the most important errors that limit the monitoring accuracy of InSAR, would lead to the masking of true phase in subsidence monitoring. For the problem, this paper used the Sentinel-1A images and the tropospheric delay maps got from GACOS to monitor the subsidence of the Yellow River Delta in Shandong Province. The conventional D-InSAR processing was performed using the GAMMA software. The MATLAB codes were used to correct the atmospheric delay of the D-InSAR results. The results before and after the atmospheric phase delay correction were verified and analyzed in the main subsidence area. The experimental results show that atmospheric phase influences the deformation results to a certain extent. After the correction, the measurement error of vertical deformation is reduced by about 18 mm, which proves that the removal of atmospheric effects can improve the accuracy of the D-InSAR monitoring.

Time Series Analysis of Insar Data: Methods and Trends

Science.gov (United States)

Osmanoglu, Batuhan; Sunar, Filiz; Wdowinski, Shimon; Cano-Cabral, Enrique

2015-01-01

Time series analysis of InSAR data has emerged as an important tool for monitoring and measuring the displacement of the Earth's surface. Changes in the Earth's surface can result from a wide range of phenomena such as earthquakes, volcanoes, landslides, variations in ground water levels, and changes in wetland water levels. Time series analysis is applied to interferometric phase measurements, which wrap around when the observed motion is larger than one-half of the radar wavelength. Thus, the spatio-temporal ''unwrapping" of phase observations is necessary to obtain physically meaningful results. Several different algorithms have been developed for time series analysis of InSAR data to solve for this ambiguity. These algorithms may employ different models for time series analysis, but they all generate a first-order deformation rate, which can be compared to each other. However, there is no single algorithm that can provide optimal results in all cases. Since time series analyses of InSAR data are used in a variety of applications with different characteristics, each algorithm possesses inherently unique strengths and weaknesses. In this review article, following a brief overview of InSAR technology, we discuss several algorithms developed for time series analysis of InSAR data using an example set of results for measuring subsidence rates in Mexico City.

a High Precision dem Extraction Method Based on Insar Data

Science.gov (United States)

Wang, Xinshuang; Liu, Lingling; Shi, Xiaoliang; Huang, Xitao; Geng, Wei

2018-04-01

In the 13th Five-Year Plan for Geoinformatics Business, it is proposed that the new InSAR technology should be applied to surveying and mapping production, which will become the innovation driving force of geoinformatics industry. This paper will study closely around the new outline of surveying and mapping and then achieve the TerraSAR/TanDEM data of Bin County in Shaanxi Province in X band. The studying steps are as follows; Firstly, the baseline is estimated from the orbital data; Secondly, the interferometric pairs of SAR image are accurately registered; Thirdly, the interferogram is generated; Fourth, the interferometric correlation information is estimated and the flat-earth phase is removed. In order to solve the phase noise and the discontinuity phase existing in the interferometric image of phase, a GAMMA adaptive filtering method is adopted. Aiming at the "hole" problem of missing data in low coherent area, the interpolation method of low coherent area mask is used to assist the phase unwrapping. Then, the accuracy of the interferometric baseline is estimated from the ground control points. Finally, 1 : 50000 DEM is generated, and the existing DEM data is used to verify the accuracy through statistical analysis. The research results show that the improved InSAR data processing method in this paper can obtain the high-precision DEM of the study area, exactly the same with the topography of reference DEM. The R2 can reach to 0.9648, showing a strong positive correlation.

Monitoring Subsidence in California with InSAR

Science.gov (United States)

Farr, T. G.; Jones, C. E.; Liu, Z.; Neff, K. L.; Gurrola, E. M.; Manipon, G.

2016-12-01

Subsidence caused by groundwater pumping in the rich agricultural area of California's Central Valley has been a problem for decades. Over the last few years, interferometric synthetic aperture radar (InSAR) observations from satellite and aircraft platforms have been used to produce maps of subsidence with cm accuracy. We are continuing work reported previously, using ESA's Sentinel-1 to extend our maps of subsidence in time and space, in order to eventually cover all of California. The amount of data to be processed has expanded exponentially in the course of our work and we are now transitioning to the use of the ARIA project at JPL to produce the time series. ARIA processing employs large Amazon cloud instances to process single or multiple frames each, scaling from one to many (20+) instances working in parallel to meet the demand (700 GB InSAR products within 3 hours). The data are stored in Amazon long-term storage and an http view of the products are available for users of the ARIA system to download the products. Higher resolution InSAR data were also acquired along the California Aqueduct by the NASA UAVSAR from 2013 - 2016. Using multiple scenes acquired by these systems, we are able to produce time series of subsidence at selected locations and transects showing how subsidence varies both spatially and temporally. The maps show that subsidence is continuing in areas with a history of subsidence and that the rates and areas affected have increased due to increased groundwater extraction during the extended western US drought. Our maps also identify and quantify new, localized areas of accelerated subsidence. The California Department of Water Resources (DWR) funded this work to provide the background and an update on subsidence in the Central Valley to support future policy. Geographic Information System (GIS) files are being furnished to DWR for further analysis of the 4 dimensional subsidence time-series maps. Part of this work was carried out at the

Seismic imaging beneath an InSAR anomaly in eastern Washington State: Shallow faulting associated with an earthquake swarm in a low-hazard area

Science.gov (United States)

Stephenson, William J.; Odum, Jackson K.; Wicks, Chuck; Pratt, Thomas L.; Blakely, Richard J.

2016-01-01

In 2001, a rare swarm of small, shallow earthquakes beneath the city of Spokane, Washington, caused ground shaking as well as audible booms over a five‐month period. Subsequent Interferometric Synthetic Aperture Radar (InSAR) data analysis revealed an area of surface uplift in the vicinity of the earthquake swarm. To investigate the potential faults that may have caused both the earthquakes and the topographic uplift, we collected ∼3  km of high‐resolution seismic‐reflection profiles to image the upper‐source region of the swarm. The two profiles reveal a complex deformational pattern within Quaternary alluvial, fluvial, and flood deposits, underlain by Tertiary basalts and basin sediments. At least 100 m of arching on a basalt surface in the upper 500 m is interpreted from both the seismic profiles and magnetic modeling. Two west‐dipping faults deform Quaternary sediments and project to the surface near the location of the Spokane fault defined from modeling of the InSAR data.

Utilization of InSAR differential interferometry for surface deformation detection caused by mining

International Nuclear Information System (INIS)

Yang, F.; Shao, Y.; Guichen, M.

2010-01-01

In China, the surface deformation of ground has been a significant geotechnical problem as a result of cracks in the ground surface, collapsing of house, and subsidence of roads. A powerful technology for detecting surface deformation in the ground is differential interferometry using synthetic aperture radar (INSAR). The technology enables the analysis from different phase of micro-wave between two observed data by synthetic aperture radar (SAR) of surface deformation of ground such as ground subsidence, land slide, and slope failure. In January 2006, the advanced land observing satellite was launched by the Japan Aerospace Exploration Agency. This paper presented an analytical investigation to detect ground subsidence or change caused by mining, overuse of ground water, and disaster. Specifically, the paper discussed the INSAR monitoring technology of the mine slope, including INSAR data sources and processing software; the principle of synthetic aperture radar interferometry; principles of differential SAR interferometry; and INSAR technology to slope monitoring of the Haizhou open pit mine. The paper also discussed the Haizhou strip mine side slope INSAR monitoring results and tests. It was concluded that the use of synthetic aperture radar interferometer technique was the optimal technique to provide three-dimensional spatial information and minimal change from ground surface by spatial remote sensing device. 18 refs., 5 figs.

Utilization of InSAR differential interferometry for surface deformation detection caused by mining

Energy Technology Data Exchange (ETDEWEB)

Yang, F. [Liaoning Technical Univ., Fuxin (China). School of Geomatics; Shao, Y. [Liaoning Technical Univ., Fuxin (China). Dept. of Foreign Language; Guichen, M. [Gifu Univ., Yanagido, Gifu (Japan). Dept. of Civil Engineering

2010-07-01

In China, the surface deformation of ground has been a significant geotechnical problem as a result of cracks in the ground surface, collapsing of house, and subsidence of roads. A powerful technology for detecting surface deformation in the ground is differential interferometry using synthetic aperture radar (INSAR). The technology enables the analysis from different phase of micro-wave between two observed data by synthetic aperture radar (SAR) of surface deformation of ground such as ground subsidence, land slide, and slope failure. In January 2006, the advanced land observing satellite was launched by the Japan Aerospace Exploration Agency. This paper presented an analytical investigation to detect ground subsidence or change caused by mining, overuse of ground water, and disaster. Specifically, the paper discussed the INSAR monitoring technology of the mine slope, including INSAR data sources and processing software; the principle of synthetic aperture radar interferometry; principles of differential SAR interferometry; and INSAR technology to slope monitoring of the Haizhou open pit mine. The paper also discussed the Haizhou strip mine side slope INSAR monitoring results and tests. It was concluded that the use of synthetic aperture radar interferometer technique was the optimal technique to provide three-dimensional spatial information and minimal change from ground surface by spatial remote sensing device. 18 refs., 5 figs.

InSAR observations of aseismic slip associated with an earthquake swarm in the Columbia River flood basalts

Science.gov (United States)

Wicks, Charles; Thelen, W.; Weaver, C.; Gomberg, J.; Rohay, A.; Bodin, P.

2011-01-01

In 2009 a swarm of small shallow earthquakes occurred within the basalt flows of the Columbia River Basalt Group (CRBG). The swarm occurred within a dense seismic network in the U.S. Department of Energys Hanford Site. Data from the seismic network along with interferometric synthetic aperture radar (InSAR) data from the European Space Agencys (ESA) ENVISAT satellite provide insight into the nature of the swarm. By modeling the InSAR deformation data we constructed a model that consists of a shallow thrust fault and a near horizontal fault. We suggest that the near horizontal lying fault is a bedding-plane fault located between basalt flows. The geodetic moment of the modeled fault system is about eight times the cumulative seismic moment of the swarm. Precise location estimates of the swarm earthquakes indicate that the area of highest slip on the thrust fault, ???70mm of slip less than ???0.5km depth, was not located within the swarm cluster. Most of the slip on the faults appears to have progressed aseismically and we suggest that interbed sediments play a central role in the slip process. Copyright 2011 by the American Geophysical Union.

Software for Generating Troposphere Corrections for InSAR Using GPS and Weather Model Data

Science.gov (United States)

Moore, Angelyn W.; Webb, Frank H.; Fishbein, Evan F.; Fielding, Eric J.; Owen, Susan E.; Granger, Stephanie L.; Bjoerndahl, Fredrik; Loefgren, Johan; Fang, Peng; Means, James D.;

Episodic inflation of Akutan volcano, Alaska revealed from GPS and InSAR time series

Science.gov (United States)

DeGrandpre, K.; Lu, Z.; Wang, T.

2016-12-01

Akutan volcano is one of the most active volcanoes located long the Aleutian arc. At least 27 eruptions have been noted since 1790 and an intense swarm of volcano-tectonic earthquakes occurred in 1996. Surface deformation after the 1996 earthquake sequence has been studied using GPS and Interferometric Synthetic Aperture Radar (InSAR) separately, yet models created from these datasets require different mechanisms to produce the observed surface deformation: an inflating Mogi source results in the best approximation of displacement observed from GPS data, whereas an opening dyke is the best fit to deformation measured from InSAR. A recent study using seismic data revealed complex magmatic structures beneath the caldera, suggesting that the surface deformation may reflect more complicated mechanisms that cannot be estimated using one type of data alone. Here we integrate the surface deformation measured from GPS and InSAR to better understand the magma plumbing system beneath Akutan volcano. GPS time-series at 12 stations from 2006 to 2016 were analyzed, and two transient episodes of inflation in 2008 and 2014 were detected. These GPS stations are, however, too sparse to reveal the spatial distribution of the surface deformation. In order to better define the spatial extent of this inflation four tracks of Envisat data acquired during 2003-2010 and one track of TerraSAR-X data acquired from 2010 to 2016 were processed to produce high-resolution maps of surface deformation. These deformation maps show a consistently uplifting area on the northwestern flank of the volcano. We inverted for the source parameters required to produce the inflation using GPS, InSAR, and a dataset of GPS and InSAR measurements combined, to find that a deep Mogi source below a shallow dyke fit these datasets best. From the TerraSAR-X data, we were also able to measure the subsidence inside the summit caldera due to fumarole activity to be as high as 10 mm/yr. The complex spatial and temporal

PAU-SA: A Synthetic Aperture Interferometric Radiometer Test Bed for Potential Improvements in Future Missions

Directory of Open Access Journals (Sweden)

Merce Vall-llosera

2012-06-01

Full Text Available The Soil Moisture and Ocean Salinity (SMOS mission is an Earth Explorer Opportunity mission from the European Space Agency (ESA. Its goal is to produce global maps of soil moisture and ocean salinity using the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS. The purpose of the Passive Advanced Unit Synthetic Aperture (PAU-SA instrument is to study and test some potential improvements that could eventually be implemented in future missions using interferometric radiometers such as the Geoestacionary Atmosferic Sounder (GAS, the Precipitation and All-weather Temperature and Humidity (PATH and the Geostationary Interferometric Microwave Sounder (GIMS. Both MIRAS and PAU-SA are Y-shaped arrays with uniformly distributed antennas, but the receiver topology and the processing unit are quite different. The purpose of this work is to identify the elements in the MIRAS’s design susceptible of improvement and apply them in the PAU-SA instrument demonstrator, to test them in view of these future interferometric radiometer missions.

Fault Creep along the Southern San Andreas from Interferometric Synthetic Aperture Radar, Permanent Scatterers, and Stacking

Science.gov (United States)

Lyons, Suzanne; Sandwell, David

2003-01-01

Interferometric synthetic aperture radar (InSAR) provides a practical means of mapping creep along major strike-slip faults. The small amplitude of the creep signal (less than 10 mm/yr), combined with its short wavelength, makes it difficult to extract from long time span interferograms, especially in agricultural or heavily vegetated areas. We utilize two approaches to extract the fault creep signal from 37 ERS SAR images along the southem San Andreas Fault. First, amplitude stacking is utilized to identify permanent scatterers, which are then used to weight the interferogram prior to spatial filtering. This weighting improves correlation and also provides a mask for poorly correlated areas. Second, the unwrapped phase is stacked to reduce tropospheric and other short-wavelength noise. This combined processing enables us to recover the near-field (approximately 200 m) slip signal across the fault due to shallow creep. Displacement maps fiom 60 interferograms reveal a diffuse secular strain buildup, punctuated by localized interseismic creep of 4-6 mm/yr line of sight (LOS, 12-18 mm/yr horizontal). With the exception of Durmid Hill, this entire segment of the southern San Andreas experienced right-lateral triggered slip of up to 10 cm during the 3.5-year period spanning the 1992 Landers earthquake. The deformation change following the 1999 Hector Mine earthquake was much smaller (4 cm) and broader than for the Landers event. Profiles across the fault during the interseismic phase show peak-to-trough amplitude ranging from 15 to 25 mm/yr (horizontal component) and the minimum misfit models show a range of creeping/locking depth values that fit the data.

Complex surface deformation of Akutan volcano, Alaska revealed from InSAR time series

Science.gov (United States)

Wang, Teng; DeGrandpre, Kimberly; Lu, Zhong; Freymueller, Jeffrey T.

2018-02-01

Akutan volcano is one of the most active volcanoes in the Aleutian arc. An intense swarm of volcano-tectonic earthquakes occurred across the island in 1996. Surface deformation after the 1996 earthquake sequence has been studied using Interferometric Synthetic Aperture Radar (InSAR), yet it is hard to determine the detailed temporal behavior and spatial extent of the deformation due to decorrelation and the sparse temporal sampling of SAR data. Atmospheric delay anomalies over Akutan volcano are also strong, bringing additional technical challenges. Here we present a time series InSAR analysis from 2003 to 2016 to reveal the surface deformation in more detail. Four tracks of Envisat data acquired from 2003 to 2010 and one track of TerraSAR-X data acquired from 2010 to 2016 are processed to produce high-resolution surface deformation, with a focus on studying two transient episodes of inflation in 2008 and 2014. For the TerraSAR-X data, the atmospheric delay is estimated and removed using the common-master stacking method. These derived deformation maps show a consistently uplifting area on the northeastern flank of the volcano. From the TerraSAR-X data, we quantify the velocity of the subsidence inside the caldera to be as high as 10 mm/year, and identify another subsidence area near the ground cracks created during the 1996 swarm.

Fault model of the 2017 Jiuzhaigou Mw 6.5 earthquake estimated from coseismic deformation observed using Global Positioning System and Interferometric Synthetic Aperture Radar data

Science.gov (United States)

Nie, Zhaosheng; Wang, Di-Jin; Jia, Zhige; Yu, Pengfei; Li, Liangfa

2018-04-01

On August 8, 2017, the Jiuzhaigou Mw 6.5 earthquake occurred in Sichuan province, southwestern China, along the eastern margin of the Tibetan Plateau. The epicenter is surrounded by the Minjiang, Huya, and Tazang Faults. As the seismic activity and tectonics are very complicated, there is controversy regarding the accurate location of the epicenter and the seismic fault of the Jiuzhaigou earthquake. To investigate these aspects, first, the coseismic deformation field was derived from Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) measurements. Second, the fault geometry, coseismic slip model, and Coulomb stress changes around the seismic region were calculated using a homogeneous elastic half-space model. The coseismic deformation field derived from InSAR measurements shows that this event was mainly dominated by a left-lateral strike-slip fault. The maximal and minimal displacements were approximately 0.15 m and - 0.21 m, respectively, along line-of-sight observation. The whole deformation field follows a northwest-trending direction and is mainly concentrated west of the fault. The coseismic slip is 28 km along the strike and 18 km along the dip. It is dominated by a left-lateral strike-slip fault. The average and maximal fault slip is 0.18 and 0.85 m, respectively. The rupture did not fully reach the ground surface. The focal mechanism derived from GPS and InSAR data is consistent with the kinematics and geometry of the Huya Fault. Therefore, we conclude that the northern section or the Shuzheng segment of the Huya Fault is the seismogenic fault. The maximal fault slip is located at 33.25°N and 103.82°E at a depth of 11 km, and the release moment is approximately 6.635 × 1018 Nm, corresponding to a magnitude of Mw 6.49, which is consistent with results reported by the US Geological Survey, Global Centroid Moment Tensor, and other researchers. The coseismic Coulomb stress changes enhanced the stress on the northwest and

Monitoring Building Deformation with InSAR: Experiments and Validation

Science.gov (United States)

Yang, Kui; Yan, Li; Huang, Guoman; Chen, Chu; Wu, Zhengpeng

2016-01-01

Synthetic Aperture Radar Interferometry (InSAR) techniques are increasingly applied for monitoring land subsidence. The advantages of InSAR include high accuracy and the ability to cover large areas; nevertheless, research validating the use of InSAR on building deformation is limited. In this paper, we test the monitoring capability of the InSAR in experiments using two landmark buildings; the Bohai Building and the China Theater, located in Tianjin, China. They were selected as real examples to compare InSAR and leveling approaches for building deformation. Ten TerraSAR-X images spanning half a year were used in Permanent Scatterer InSAR processing. These extracted InSAR results were processed considering the diversity in both direction and spatial distribution, and were compared with true leveling values in both Ordinary Least Squares (OLS) regression and measurement of error analyses. The detailed experimental results for the Bohai Building and the China Theater showed a high correlation between InSAR results and the leveling values. At the same time, the two Root Mean Square Error (RMSE) indexes had values of approximately 1 mm. These analyses show that a millimeter level of accuracy can be achieved by means of InSAR technique when measuring building deformation. We discuss the differences in accuracy between OLS regression and measurement of error analyses, and compare the accuracy index of leveling in order to propose InSAR accuracy levels appropriate for monitoring buildings deformation. After assessing the advantages and limitations of InSAR techniques in monitoring buildings, further applications are evaluated. PMID:27999403

Monitoring Building Deformation with InSAR: Experiments and Validation

Directory of Open Access Journals (Sweden)

Kui Yang

2016-12-01

Full Text Available Synthetic Aperture Radar Interferometry (InSAR techniques are increasingly applied for monitoring land subsidence. The advantages of InSAR include high accuracy and the ability to cover large areas; nevertheless, research validating the use of InSAR on building deformation is limited. In this paper, we test the monitoring capability of the InSAR in experiments using two landmark buildings; the Bohai Building and the China Theater, located in Tianjin, China. They were selected as real examples to compare InSAR and leveling approaches for building deformation. Ten TerraSAR-X images spanning half a year were used in Permanent Scatterer InSAR processing. These extracted InSAR results were processed considering the diversity in both direction and spatial distribution, and were compared with true leveling values in both Ordinary Least Squares (OLS regression and measurement of error analyses. The detailed experimental results for the Bohai Building and the China Theater showed a high correlation between InSAR results and the leveling values. At the same time, the two Root Mean Square Error (RMSE indexes had values of approximately 1 mm. These analyses show that a millimeter level of accuracy can be achieved by means of InSAR technique when measuring building deformation. We discuss the differences in accuracy between OLS regression and measurement of error analyses, and compare the accuracy index of leveling in order to propose InSAR accuracy levels appropriate for monitoring buildings deformation. After assessing the advantages and limitations of InSAR techniques in monitoring buildings, further applications are evaluated.

The Temporal and Spatial Variability of the Confined Aquifer Head and Storage Properties in the San Luis Valley, Colorado Inferred From Multiple InSAR Missions

Science.gov (United States)

Chen, Jingyi; Knight, Rosemary; Zebker, Howard A.

2017-11-01

Interferometric Synthetic Aperture Radar (InSAR) data from multiple satellite missions were combined to study the temporal and spatial variability of head and storage properties in a confined aquifer system on a decadal time scale. The area of study was a 4,500 km2 agricultural basin in the San Luis Valley (SLV), Colorado. We had available previous analyses of C-band ERS-1/2 data from June 1992 to November 2000, and L-band ALOS PALSAR data from October 2009 to March 2011. We used C-band Envisat data to fill in the time period from November 2006 to July 2010. In processing the Envisat data, we successfully employed a phase interpolation between persistent scatterer pixels to reduce the impact of vegetation decorrelation, which can significantly reduce the quality of C-band InSAR data over agricultural basins. In comparing the results from the L-band ALOS data and C-band Envisat data in a 10 month overlapping time period, we found that the shorter wavelength of C-band InSAR allowed us to preserve small deformation signals that were not detectable using L-band ALOS data. A significant result was the finding that the elastic storage properties of the SLV confined aquifer system remained stable over the 20 year time period and vary slowly in space, allowing us to combine InSAR data acquired from multiple missions to fill the temporal and spatial gaps in well data. The InSAR estimated head levels were validated with well measurements, which indicate little permanent water-storage loss over the study time period in the SLV.

INVESTIGATION OF LITHOSPHERIC STRUCTURE IN MONGOLIA: INSIGHTS FROM INSAR OBSERVATIONS AND MODELLING

Directory of Open Access Journals (Sweden)

Z. Jing

2017-09-01

Full Text Available The western Mongolia is a seismically active intracontinental region, with ongoing tectonic deformation and widespread seismicity related to the far-field effects of India-Eurasia collision. During the 20th century, four earthquakes with the magnitude larger than 8 occurred in the western Mongolia and its surrounding regions, providing a unique opportunity to study the geodynamics of intracontinental tectonic deformations. The 1957 magnitude 8.3 Gobi-Altai earthquake is one of the largest seismic events. The deformation pattern of rupture zone associated with this earthquake is complex, involving left-lateral strike-slip and reverse dip-slip faulting on several distinct geological structures in a 264 × 40 km wide zone. To understand the relationship between the observed postseismic surface deformation and the rheological structure of the upper lithosphere, Interferometric Synthetic Aperture Radar (InSAR data are used to study the 1957 earthquake. Then we developed a postseismic model in a spherical, radially layered elastic-viscoelastic Earth based on InSAR results, and further analysed the dominant contribution to the surface deformation. This work is important for understanding not only the regional tectonics, but also the structure and dynamics of the lithosphere. SAR data were acquired from the ERS1/2 and Envisat from 1996 to 2010. Using the Repeat Orbit Interferometry Package (ROI_PAC, 124 postseismic interferograms are produced on four adjacent tracks. By stacking these interferograms, the maximum InSAR line-of-sight deformation rate along the Gobi-Altai fault zone is obtained. The main results are as follows: (1 The maximum InSAR line-of-sight deformation velocity along this large fault zone is about 6 mm/yr; (2 The modelled surface deformation suggests that the viscoelastic relaxation is the most reasonable mechanism to explain the observed surface motion; (3 The optimal model cover the Gobi-Altai seismogenic thickness is 10�

The rapid terrain visualization interferometric synthetic aperture radar sensor

Science.gov (United States)

Graham, Robert H.; Bickel, Douglas L.; Hensley, William H.

2003-11-01

The Rapid Terrain Visualization interferometric synthetic aperture radar was designed and built at Sandia National Laboratories as part of an Advanced Concept Technology Demonstration (ACTD) to "demonstrate the technologies and infrastructure to meet the Army requirement for rapid generation of digital topographic data to support emerging crisis or contingencies." This sensor is currently being operated by Sandia National Laboratories for the Joint Precision Strike Demonstration (JPSD) Project Office to provide highly accurate digital elevation models (DEMs) for military and civilian customers, both inside and outside of the United States. The sensor achieves better than DTED Level IV position accuracy in near real-time. The system is being flown on a deHavilland DHC-7 Army aircraft. This paper outlines some of the technologies used in the design of the system, discusses the performance, and will discuss operational issues. In addition, we will show results from recent flight tests, including high accuracy maps taken of the San Diego area.

Applications of interferometrically derived terrain slopes: Normalization of SAR backscatter and the interferometric correlation coefficient

Science.gov (United States)

Werner, Charles L.; Wegmueller, Urs; Small, David L.; Rosen, Paul A.

1994-01-01

Terrain slopes, which can be measured with Synthetic Aperture Radar (SAR) interferometry either from a height map or from the interferometric phase gradient, were used to calculate the local incidence angle and the correct pixel area. Both are required for correct thematic interpretation of SAR data. The interferometric correlation depends on the pixel area projected on a plane perpendicular to the look vector and requires correction for slope effects. Methods for normalization of the backscatter and interferometric correlation for ERS-1 SAR are presented.

Combined DEM Extration Method from StereoSAR and InSAR

Science.gov (United States)

Zhao, Z.; Zhang, J. X.; Duan, M. Y.; Huang, G. M.; Yang, S. C.

2015-06-01

A pair of SAR images acquired from different positions can be used to generate digital elevation model (DEM). Two techniques exploiting this characteristic have been introduced: stereo SAR and interferometric SAR. They permit to recover the third dimension (topography) and, at the same time, to identify the absolute position (geolocation) of pixels included in the imaged area, thus allowing the generation of DEMs. In this paper, StereoSAR and InSAR combined adjustment model are constructed, and unify DEM extraction from InSAR and StereoSAR into the same coordinate system, and then improve three dimensional positioning accuracy of the target. We assume that there are four images 1, 2, 3 and 4. One pair of SAR images 1,2 meet the required conditions for InSAR technology, while the other pair of SAR images 3,4 can form stereo image pairs. The phase model is based on InSAR rigorous imaging geometric model. The master image 1 and the slave image 2 will be used in InSAR processing, but the slave image 2 is only used in the course of establishment, and the pixels of the slave image 2 are relevant to the corresponding pixels of the master image 1 through image coregistration coefficient, and it calculates the corresponding phase. It doesn't require the slave image in the construction of the phase model. In Range-Doppler (RD) model, the range equation and Doppler equation are a function of target geolocation, while in the phase equation, the phase is also a function of target geolocation. We exploit combined adjustment model to deviation of target geolocation, thus the problem of target solution is changed to solve three unkonwns through seven equations. The model was tested for DEM extraction under spaceborne InSAR and StereoSAR data and compared with InSAR and StereoSAR methods respectively. The results showed that the model delivered a better performance on experimental imagery and can be used for DEM extraction applications.

An L-band interferometric synthetic aperture radar study on the Ganos section of the north Anatolian fault zone between 2007 and 2011: Evidence for along strike segmentation and creep in a shallow fault patch.

Science.gov (United States)

de Michele, Marcello; Ergintav, Semih; Aochi, Hideo; Raucoules, Daniel

2017-01-01

We utilize L-band interferometric synthetic aperture radar (InSAR) data in this study to retrieve a ground velocity map for the near field of the Ganos section of the north Anatolian fault (NAF) zone. The segmentation and creep distribution of this section, which last ruptured in 1912 to generate a moment magnitude (Mw)7.3 earthquake, remains incompletely understood. Because InSAR processing removes the mean orbital plane, we do not investigate large scale displacements due to regional tectonics in this study as these can be determined using global positioning system (GPS) data, instead concentrating on the close-to-the-fault displacement field. Our aim is to determine whether, or not, it is possible to retrieve robust near field velocity maps from stacking L-band interferograms, combining both single and dual polarization SAR data. In addition, we discuss whether a crustal velocity map can be used to complement GPS observations in an attempt to discriminate the present-day surface displacement of the Ganos fault (GF) across multiple segments. Finally, we characterize the spatial distribution of creep on shallow patches along multiple along-strike segments at shallow depths. Our results suggest the presence of fault segmentation along strike as well as creep on the shallow part of the fault (i.e. the existence of a shallow creeping patch) or the presence of a smoother section on the fault plane. Data imply a heterogeneous fault plane with more complex mechanics than previously thought. Because this study improves our knowledge of the mechanisms underlying the GF, our results have implications for local seismic hazard assessment.

Identifying Active Faults by Improving Earthquake Locations with InSAR Data and Bayesian Estimation: The 2004 Tabuk (Saudi Arabia) Earthquake Sequence

KAUST Repository

Xu, Wenbin

2015-02-03

A sequence of shallow earthquakes of magnitudes ≤5.1 took place in 2004 on the eastern flank of the Red Sea rift, near the city of Tabuk in northwestern Saudi Arabia. The earthquakes could not be well located due to the sparse distribution of seismic stations in the region, making it difficult to associate the activity with one of the many mapped faults in the area and thus to improve the assessment of seismic hazard in the region. We used Interferometric Synthetic Aperture Radar (InSAR) data from the European Space Agency’s Envisat and ERS‐2 satellites to improve the location and source parameters of the largest event of the sequence (Mw 5.1), which occurred on 22 June 2004. The mainshock caused a small but distinct ∼2.7  cm displacement signal in the InSAR data, which reveals where the earthquake took place and shows that seismic reports mislocated it by 3–16 km. With Bayesian estimation, we modeled the InSAR data using a finite‐fault model in a homogeneous elastic half‐space and found the mainshock activated a normal fault, roughly 70 km southeast of the city of Tabuk. The southwest‐dipping fault has a strike that is roughly parallel to the Red Sea rift, and we estimate the centroid depth of the earthquake to be ∼3.2  km. Projection of the fault model uncertainties to the surface indicates that one of the west‐dipping normal faults located in the area and oriented parallel to the Red Sea is a likely source for the mainshock. The results demonstrate how InSAR can be used to improve locations of moderate‐size earthquakes and thus to identify currently active faults.

Identifying Active Faults by Improving Earthquake Locations with InSAR Data and Bayesian Estimation: The 2004 Tabuk (Saudi Arabia) Earthquake Sequence

KAUST Repository

Xu, Wenbin; Dutta, Rishabh; Jonsson, Sigurjon

2015-01-01

A sequence of shallow earthquakes of magnitudes ≤5.1 took place in 2004 on the eastern flank of the Red Sea rift, near the city of Tabuk in northwestern Saudi Arabia. The earthquakes could not be well located due to the sparse distribution of seismic stations in the region, making it difficult to associate the activity with one of the many mapped faults in the area and thus to improve the assessment of seismic hazard in the region. We used Interferometric Synthetic Aperture Radar (InSAR) data from the European Space Agency’s Envisat and ERS‐2 satellites to improve the location and source parameters of the largest event of the sequence (Mw 5.1), which occurred on 22 June 2004. The mainshock caused a small but distinct ∼2.7  cm displacement signal in the InSAR data, which reveals where the earthquake took place and shows that seismic reports mislocated it by 3–16 km. With Bayesian estimation, we modeled the InSAR data using a finite‐fault model in a homogeneous elastic half‐space and found the mainshock activated a normal fault, roughly 70 km southeast of the city of Tabuk. The southwest‐dipping fault has a strike that is roughly parallel to the Red Sea rift, and we estimate the centroid depth of the earthquake to be ∼3.2  km. Projection of the fault model uncertainties to the surface indicates that one of the west‐dipping normal faults located in the area and oriented parallel to the Red Sea is a likely source for the mainshock. The results demonstrate how InSAR can be used to improve locations of moderate‐size earthquakes and thus to identify currently active faults.

INSAR For Early Warning Of Possible Highway Instability Over Undermined Area Of Ostrava

Science.gov (United States)

Lazecky, Milan; Kacmarik, Michal; Rapant, Petr

2012-01-01

A part of czech highway D1 connecting Ostrava with Prague and Poland, is built over an undermined area of Ostrava-Svinov. Since the end of 2010, this part of the highway is fully operational. Because of undermining, a subsidence can be expected, however with a very slow rate since the mines are no more active in this area. Several TerraSAR-X images from 2011 are investigated interferometrically in order to estimate a precise deformation model. Subjects of interest are movements of newly built highway bridges, banks and close neighbourhood. Existing C-band multitemporal InSAR processing results of ERS and Envisat are available from an earlier period that reveil a slow trend of residual subsidence. In this project, InSAR will be investigated as a tool for an early warning for highway stability.

Engaging students in geodesy: A quantitative InSAR module for undergraduate tectonics and geophysics classes

Science.gov (United States)

Taylor, H.; Charlevoix, D. J.; Pritchard, M. E.; Lohman, R. B.

2013-12-01

In the last several decades, advances in geodetic technology have allowed us to significantly expand our knowledge of processes acting on and beneath the Earth's surface. Many of these advances have come as a result of EarthScope, a community of scientists conducting multidisciplinary Earth science research utilizing freely accessible data from a variety of instruments. The geodetic component of EarthScope includes the acquisition of synthetic aperture radar (SAR) images, which are archived at the UNAVCO facility. Interferometric SAR complements the spatial and temporal coverage of GPS and allows monitoring of ground deformation in remote areas worldwide. However, because of the complex software required for processing, InSAR data are not readily accessible to most students. Even with these challenges, exposure at the undergraduate level is important for showing how geodesy can be applied in various areas of the geosciences and for promoting geodesy as a future career path. Here we present a module focused on exploring the tectonics of the western United States using InSAR data for use in undergraduate tectonics and geophysics classes. The module has two major objectives: address topics concerning tectonics in the western U.S. including Basin and Range extension, Yellowstone hotspot activity, and creep in southern California, and familiarize students with how imperfect real-world data can be manipulated and interpreted. Module questions promote critical thinking skills and data literacy by prompting students to use the information given to confront and question assumptions (e.g. 'Is there a consistency between seismic rates and permanent earthquake deformation? What other factors might need to be considered besides seismicity?'). The module consists of an introduction to the basics of InSAR and three student exercises, each focused on one of the topics listed above. Students analyze pre-processed InSAR data using MATLAB, or an Excel equivalent, and draw on GPS and

Surface deformation induced by magmatic processes at Pacaya Volcano, Guatemala revealed by InSAR

Science.gov (United States)

Wnuk, K.; Wauthier, C.

2017-09-01

Pacaya Volcano, Guatemala is a continuously active, basaltic volcano with an unstable western flank. Despite continuous activity since 1961, a lack of high temporal resolution geodetic surveying has prevented detailed modeling of Pacaya's underlying magmatic plumbing system. A new, temporally dense dataset of Interferometric Synthetic Aperture Radar (InSAR) RADARSAT-2 images, spanning December 2012 to March 2014, show magmatic deformation before and during major eruptions in January and March 2014. Inversion of InSAR surface displacements using simple analytical forward models suggest that three magma bodies are responsible for the observed deformation: (1) a 4 km deep spherical reservoir located northwest of the summit, (2) a 0.4 km deep spherical source located directly west of the summit, and (3) a shallow dike below the summit. Periods of heightened volcanic activity are instigated by magma pulses at depth, resulting in rapid inflation of the edifice. We observe an intrusion cycle at Pacaya that consists of deflation of one or both magma reservoirs followed by dike intrusion. Intrusion volumes are proportional to reservoir volume loss and do not always result in an eruption. Periods of increased activity culminate with larger dike-fed eruptions. Large eruptions are followed by inter-eruptive periods marked by a decrease in crater explosions and a lack of detected deformation. Co-eruptive flank motion appears to have initiated a new stage of volcanic rifting at Pacaya defined by repeated NW-SE oriented dike intrusions. This creates a positive feedback relationship whereby magmatic forcing from eruptive dike intrusions induce flank motion.

InSAR data for geohazard assessment in UNESCO World Heritage sites: state-of-the-art and perspectives in the Copernicus era

Science.gov (United States)

Tapete, Deodato; Cigna, Francesca

2017-12-01

Protection of natural and cultural heritage is encompassed by the United Nations' 2030 Agenda for Sustainable Development and is among the innovative applications and services of the European Union's Earth Observation programme Copernicus. We are currently witnessing an increasing exploitation of Interferometric Synthetic Aperture Radar (InSAR) methods to assess geohazards affecting cultural heritage. This paper offers the first data mining exercise to identify InSAR geoinformation that is digitally available and/or published and that spatially includes one or more cultural, natural and mixed UNESCO World Heritage Site (WHS). The exercise focused on the 45 countries of geographical Europe, Turkey, Israel and the Russian Federation, and their 445 WHS of Outstanding Universal Value. We built a database of academic and grey literature collated via a Boolean search of the ISI Web of Science catalogue and systematic skim-reading to a total number of 280 publications as of the end of 2016. Over 460 InSAR open access digital datasets were also analysed. We found clusters of WHS covered by InSAR data in Italy, the Netherlands, western Germany, eastern Spain, Greece and the UK that match with the geographic distribution of InSAR expertise and geohazard hotspots. The existing stock of InSAR geoinformation already provides an overall WHS coverage of 36%, with similar proportion of available data for 'urban' (40%) and 'rural' (34%) WHS. The sites with the highest number of publications are historic city centres (e.g. Amsterdam, Athens, Barcelona, Lisbon, Paris, Rome), as well as Permanent Geohazard Supersites (e.g. Mt. Etna, Naples, Istanbul), where the impact of natural and/or anthropogenic processes is well known. First generation SAR data (mainly ERS-1/2) predominate in the literature with over 15 new publications/year since 2002, whilst second and third generation data show less pronounced rates since 2007 and 2014, respectively. The current engagement level of end

Integrating gravimetric and interferometric synthetic aperture radar data for enhancing reservoir history matching of carbonate gas and volatile oil reservoirs

KAUST Repository

Katterbauer, Klemens

2016-08-25

Reservoir history matching is assuming a critical role in understanding reservoir characteristics, tracking water fronts, and forecasting production. While production data have been incorporated for matching reservoir production levels and estimating critical reservoir parameters, the sparse spatial nature of this dataset limits the efficiency of the history matching process. Recently, gravimetry techniques have significantly advanced to the point of providing measurement accuracy in the microgal range and consequently can be used for the tracking of gas displacement caused by water influx. While gravity measurements provide information on subsurface density changes, i.e., the composition of the reservoir, these data do only yield marginal information about temporal displacements of oil and inflowing water. We propose to complement gravimetric data with interferometric synthetic aperture radar surface deformation data to exploit the strong pressure deformation relationship for enhancing fluid flow direction forecasts. We have developed an ensemble Kalman-filter-based history matching framework for gas, gas condensate, and volatile oil reservoirs, which synergizes time-lapse gravity and interferometric synthetic aperture radar data for improved reservoir management and reservoir forecasts. Based on a dual state-parameter estimation algorithm separating the estimation of static reservoir parameters from the dynamic reservoir parameters, our numerical experiments demonstrate that history matching gravity measurements allow monitoring the density changes caused by oil-gas phase transition and water influx to determine the saturation levels, whereas the interferometric synthetic aperture radar measurements help to improve the forecasts of hydrocarbon production and water displacement directions. The reservoir estimates resulting from the dual filtering scheme are on average 20%-40% better than those from the joint estimation scheme, but require about a 30% increase in

Visible Earthquakes: a web-based tool for visualizing and modeling InSAR earthquake data

Science.gov (United States)

Funning, G. J.; Cockett, R.

2012-12-01

InSAR (Interferometric Synthetic Aperture Radar) is a technique for measuring the deformation of the ground using satellite radar data. One of the principal applications of this method is in the study of earthquakes; in the past 20 years over 70 earthquakes have been studied in this way, and forthcoming satellite missions promise to enable the routine and timely study of events in the future. Despite the utility of the technique and its widespread adoption by the research community, InSAR does not feature in the teaching curricula of most university geoscience departments. This is, we believe, due to a lack of accessibility to software and data. Existing tools for the visualization and modeling of interferograms are often research-oriented, command line-based and/or prohibitively expensive. Here we present a new web-based interactive tool for comparing real InSAR data with simple elastic models. The overall design of this tool was focused on ease of access and use. This tool should allow interested nonspecialists to gain a feel for the use of such data and greatly facilitate integration of InSAR into upper division geoscience courses, giving students practice in comparing actual data to modeled results. The tool, provisionally named 'Visible Earthquakes', uses web-based technologies to instantly render the displacement field that would be observable using InSAR for a given fault location, geometry, orientation, and slip. The user can adjust these 'source parameters' using a simple, clickable interface, and see how these affect the resulting model interferogram. By visually matching the model interferogram to a real earthquake interferogram (processed separately and included in the web tool) a user can produce their own estimates of the earthquake's source parameters. Once satisfied with the fit of their models, users can submit their results and see how they compare with the distribution of all other contributed earthquake models, as well as the mean and median

Semantic Interpretation of Insar Estimates Using Optical Images with Application to Urban Infrastructure Monitoring

Science.gov (United States)

Wang, Y.; Zhu, X. X.

2015-08-01

Synthetic aperture radar interferometry (InSAR) has been an established method for long term large area monitoring. Since the launch of meter-resolution spaceborne SAR sensors, the InSAR community has shown that even individual buildings can be monitored in high level of detail. However, the current deformation analysis still remains at a primitive stage of pixel-wise motion parameter inversion and manual identification of the regions of interest. We are aiming at developing an automatic urban infrastructure monitoring approach by combining InSAR and the semantics derived from optical images, so that the deformation analysis can be done systematically in the semantic/object level. This paper explains how we transfer the semantic meaning derived from optical image to the InSAR point clouds, and hence different semantic classes in the InSAR point cloud can be automatically extracted and monitored. Examples on bridges and railway monitoring are demonstrated.

Structural Health and Stability Assessment of High-Speed Railways via Thermal Dilation Mapping With Time-Series InSAR Analysis

NARCIS (Netherlands)

Qin, Xiaoqiong; Liao, Mingsheng; Zhang, L; Yang, M.

2017-01-01

Thermal dilation is a vital component of deformation along the extensive railway network infrastructure. To monitor subtle deformation, the synthetic aperture radar interferometry (InSAR) technique has been adopted as a space-borne geodetic tool. However, InSAR applications in railway stability

Pre-eruption deformation caused by dike intrusion beneath Kizimen volcano, Kamchatka, Russia, observed by InSAR

Science.gov (United States)

Ji, Lingyun; Lu, Zhong; Dzurisin, Daniel; Senyukov, Sergey

2013-01-01

Interferometric synthetic aperture radar (InSAR) images reveal a pre-eruption deformation signal at Kizimen volcano, Kamchatka, Russia, where an ongoing eruption began in mid-November, 2010. The previous eruption of this basaltic andesite-to-dacite stratovolcano occurred in 1927–1928. InSAR images from both ascending and descending orbital passes of Envisat and ALOS PALSAR satellites show as much as 6 cm of line-of-sight shortening from September 2008 to September 2010 in a broad area centered at Kizimen. About 20 cm of opening of a nearly vertical dike provides an adequate fit to the surface deformation pattern. The model dike is approximately 14 km long, 10 km high, centered 13 km beneath Kizimen, and strikes NE–SW. Time-series analysis of multi-temporal interferograms indicates that (1) intrusion started sometime between late 2008 and July 2009, (2) continued at a nearly constant rate, and (3) resulted in a volume expansion of 3.2 × 107 m3 by September 2010, i.e., about two months before the onset of the 2010 eruption. Earthquakes located above the tip of the dike accompanied the intrusion. Eventually, magma pressure in the dike exceeded the confining strength of the host rock, triggering the 2010 eruption. Our results provide insight into the intrusion process that preceded an explosive eruption at a Pacific Rim stratovolcano following nearly a century of quiescence, and therefore have implications for monitoring and hazards assessment at similar volcanoes elsewhere.

Evaluation of LIDAR for Automating Recognition of Roads and Trails Beneath Forest Canopy

Science.gov (United States)

2011-09-01

Measurement Unit InSAR Interferometric Synthetic Aperture Radar ISS International Space Station JALBTCX Joint Airborne LiDAR Bathymetry Technical Center of...California police arrest 100 over marijuana growing. Retrieved July 29, 2011, from http://www.bbc.co.uk/news/world–us–canada–14351501 Contreras, M

InSAR Analysis of Post-Seismic Deformation Following the 2013 Mw 7.7 Balochistan, Pakistan Earthquake

Science.gov (United States)

Peterson, K.; Barnhart, W. D.

2017-12-01

On September 24th, 2013, a Mw 7.7 earthquake ruptured a 200 km portion of the Hoshab fault, a reverse fault in the Makran accretionary prism of southern Pakistan. This earthquake is notable because it ruptured a reverse fault with a predominantly strike-slip sense of displacement, and it ruptured a mechanically weak accretionary prism. Here, we present initial analysis of ongoing post-seismic deformation imaged with the Sentinel-1 interferometric synthetic aperture radar (InSAR) mission with the goals of a) determining the dominant post-seismic deformation processes active, b) characterizing the rigidity and rheological structure of a flat-slab subduction zone, and c) elucidating whether post-seismic deformation may account for or exacerbate the 4-6 m fault convergence deficit left by the 2013 earthquake. We first present InSAR time series analysis of the post-seismic transient derived from ongoing Sentinel-1 SAR acquisitions, including a comparison of atmosphere-corrected and uncorrected time series. Interferograms spanning December 2014 to the present reveal an ongoing post-seismic deformation transient in the region surrounding the Hoshab fault. Additionally, fault creep signals on and adjacent to the Hoshab fault are present. Second, we present a suite of forward models that explore the potential contributions of viscoelastic relaxation and frictional afterslip to the recorded displacement signal. These models, conducted using the semi-analytical solutions of RELAX and compared to InSAR line-of-sight time series displacements, explore a range of candidate rheological descriptions of the Makran subduction zone that are designed to probe the rheological structure of a region where current knowledge of the subsurface geology is highly limited. Our preliminary results suggest that post-seismic displacements arise from a combination of viscoelastic deformation and frictional afterslip, as opposed to one single mechanism. Additionally, our preliminary results suggest

Spatial and temporal patterns of deformation at the Tendaho geothermal prospect, Ethiopia

OpenAIRE

Tessema, Tesfaye; Biggs, Juliet; Lewi, Elias; Hamling , Ian; Wright, Tim; Ayele, Atalay

2018-01-01

Observations of ground deformation in East Africa have been fundamental for unveiling the tectonics of continental rifting, assessing the seismic and volcanic hazard to development, and identifying geothermal resources. Here we investigate the active natural and anthropogenic processes in the Tendaho Graben, Afar using Interferometric Synthetic Aperture Radar (InSAR) collected by the Envisat satellite in 2004–2010. We used the Poly-Interferometric Rate And time series Estimation (π-RATE) meth...

Rapid groundwater-related land subsidence in Yemen observed by multi-temporal InSAR

KAUST Repository

Abdullin, Ayrat

2015-04-01

Several basins in Yemen are suffering from a rapid drawdown of groundwater, which is the most important water source for agricultural irrigation, industry and domestic use. However, detailed geodetic measurements in the region have been lacking and the extent and magnitude of groundwater-related land subsidence has been poorly known. We used 13 ascending ALOS and 15 descending Envisat images to study land subsidence of several basins in Yemen, with a special focus on the Sana\\'a and Mabar basins. From multitemporal synthetic aperture radar interferometric analysis (persistent scatterers (PS) and small baseline subsets (SBAS)) we examined the spatio-temporal behavior of the subsidence induced by depletion of groundwater aquifer systems from November 2003 to February 2011. In the interferometric data processing, we carefully chose interferogram pairs to minimize spatial and temporal decorrelation, because of high subsidence rates and the type of land cover. Our results show that the spatial pattern of subsidence remained quite stable during the observation period in both the Sana\\'a and Mabar basins. In the Sana\\'a basin, the maximum subsidence rate exceeded 14 cm/year in the radar line-of-sight (LOS) direction between 2003 and 2008 in an agricultural area just north of Sana\\'a city, where water wells have been drying up according to the well data. The subsidence rate was lower in the urban areas, or approximately 1 cm/year, exhibiting annual variations. The main subsidence was found in the center and southern parts of the city, while deformation in the northern part is less obvious. For the Mabar basin, the subsidence rate exceeded 30 cm/year in the agricultural area north of the town of Mabar during 2007 - 2011. The southern part of the Mabar basin also experienced high subsidence rates, although somewhat lower than to the north. Excessive water pumping is the main cause of the ground subsidence and it has already led to extensive ground fracturing at the edge

Rapid groundwater-related land subsidence in Yemen observed by multi-temporal InSAR

Science.gov (United States)

Abdullin, Ayrat; Xu, Wenbin; Kosmicki, Maximillian; Jonsson, Sigurjon

2015-04-01

Several basins in Yemen are suffering from a rapid drawdown of groundwater, which is the most important water source for agricultural irrigation, industry and domestic use. However, detailed geodetic measurements in the region have been lacking and the extent and magnitude of groundwater-related land subsidence has been poorly known. We used 13 ascending ALOS and 15 descending Envisat images to study land subsidence of several basins in Yemen, with a special focus on the Sana'a and Mabar basins. From multitemporal synthetic aperture radar interferometric analysis (persistent scatterers (PS) and small baseline subsets (SBAS)) we examined the spatio-temporal behavior of the subsidence induced by depletion of groundwater aquifer systems from November 2003 to February 2011. In the interferometric data processing, we carefully chose interferogram pairs to minimize spatial and temporal decorrelation, because of high subsidence rates and the type of land cover. Our results show that the spatial pattern of subsidence remained quite stable during the observation period in both the Sana'a and Mabar basins. In the Sana'a basin, the maximum subsidence rate exceeded 14 cm/year in the radar line-of-sight (LOS) direction between 2003 and 2008 in an agricultural area just north of Sana'a city, where water wells have been drying up according to the well data. The subsidence rate was lower in the urban areas, or approximately 1 cm/year, exhibiting annual variations. The main subsidence was found in the center and southern parts of the city, while deformation in the northern part is less obvious. For the Mabar basin, the subsidence rate exceeded 30 cm/year in the agricultural area north of the town of Mabar during 2007 - 2011. The southern part of the Mabar basin also experienced high subsidence rates, although somewhat lower than to the north. Excessive water pumping is the main cause of the ground subsidence and it has already led to extensive ground fracturing at the edge of some

Assimilation of Deformation Data for Eruption Forecasting: Potentiality Assessment Based on Synthetic Cases

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M. Grace Bato

2017-06-01

Full Text Available In monitoring active volcanoes, the magma overpressure is one of the key parameters used in forecasting volcanic eruptions. This parameter can be inferred from the ground displacements measured on the Earth's surface by applying inversion techniques. However, in most studies, the huge amount of information about the behavior of the volcano contained in the temporal evolution of the deformation signal is not fully exploited by inversion. Our work focuses on developing a strategy in order to better forecast the magma overpressure using data assimilation. We take advantage of the increasing amount of geodetic data [i.e., Interferometric Synthetic Aperture Radar (InSAR and Global Navigation Satellite System (GNSS] recorded on volcanoes nowadays together with the wide-range availability of dynamical models that can provide better understanding about the volcano plumbing system. Here, we particularly built our strategy on the basis of the Ensemble Kalman Filter (EnKF. We forecast the temporal behaviors of the magma overpressures and surface deformations by adopting a simple and generic two-magma chamber model and by using synthetic GNSS and/or InSAR data. We prove the ability of EnKF to both estimate the magma pressure evolution and constrain the characteristics of the deep volcanic system (i.e., reservoir size as well as basal magma inflow. High temporal frequency of observation is required to ensure the success of EnKF and the quality of assimilation is also improved by increasing the spatial density of observations in the near-field. We thus show that better results are obtained by combining a few GNSS temporal series of high temporal resolution with InSAR images characterized by a good spatial coverage. We also show that EnKF provides similar results to sophisticated Bayesian-based inversion while using the same dynamical model with the advantage of EnKF to potentially account for the temporal evolution of the uncertain model parameters. Our

AN ASSESSMENT OF SPACEBORNE NEAR-NADIR INTERFEROMETRIC SAR PERFORMANCE OVER INLAND WATERS WITH REAL

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H. Tan

2018-04-01

Full Text Available Elevation measurements of the continental water surface have been poorly collected with in situ measurements or occasionally with conventional altimeters with low accuracy. Techniques using InSAR at near-nadir angles to measure the inland water elevation with large swath and with high accuracy have been proposed, for instance, the WSOA on Jason 2 and the KaRIn on SWOT. However, the WSOA was abandoned unfortunately and the SWOT is planned to be launched in 2021. In this paper, we show real acquisitions of the first spaceborne InSAR of such kind, the Interferometric Imaging Radar Altimeter (InIRA, which has been working on Tiangong II spacecraft since 2016. We used the 90-m SRTM DEM as a reference to estimate the phase offset, and then an empirical calibration model was used to correct the baseline errors.

An Assessment of Spaceborne Near-Nadir Interferometric SAR Performance Over Inland Waters with Real

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Tan, H.; Li, S. Y.; Liu, Z. W.

2018-04-01

Elevation measurements of the continental water surface have been poorly collected with in situ measurements or occasionally with conventional altimeters with low accuracy. Techniques using InSAR at near-nadir angles to measure the inland water elevation with large swath and with high accuracy have been proposed, for instance, the WSOA on Jason 2 and the KaRIn on SWOT. However, the WSOA was abandoned unfortunately and the SWOT is planned to be launched in 2021. In this paper, we show real acquisitions of the first spaceborne InSAR of such kind, the Interferometric Imaging Radar Altimeter (InIRA), which has been working on Tiangong II spacecraft since 2016. We used the 90-m SRTM DEM as a reference to estimate the phase offset, and then an empirical calibration model was used to correct the baseline errors.

Constraints on timescales and mechanics of magmatic underplating from InSAR observations of large active magma sills in the Earth's crust.

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Fialko, Y.

2002-12-01

Theoretical models of the granitoid magma generation due to magmatic underplating predict that anatectic melts are produced on quite short timescales of the order of the crystallization time of typical mafic underplates (e.g., 102-10^3 years for sill intrusions that are a few tens to a few hundred meters thick). If so, the intrusion of mafic underplates, the volume changes associated with in situ melting, and the subsequent evacuation of the resulting granitoid magmas can each generate geodetically observable deformation. Geodetic measurements in areas of contemporaneous large active magma bodies may therefore provide critical constraints on the timescales and dynamics of crustal anatexis. We use Interferometric Synthetic Aperture Radar (InSAR) observations in regions of the ongoing crustal magmatism to constrain typical rates of the large-scale melt generation and/or migration, and to test the proposed models of the granitic melt production. Our primary targets include large mid-crustal magma bodies imaged by seismic studies, in particular, the Socorro (New Mexico, USA), the Altiplano-Puna (south America), and the south Tibet (Asia) magma bodies. All these magma bodies are located at depth of 19-20 km, suggesting a strong rheological or buoyancy control on the transition from a vertical to a horizontal magma flow. Stacked interferometric data from the Socorro magma body indicate a quasi-steady uplift with a maximum rate of 3-4 mm/yr over the last 10 years covered by the InSAR observations. The uplift morphology can be well described by an elastic inflation of the Socorro sill. We show that deformation models that allow for the viscous-like rheology of the mid-to-lower crust cannot be easily reconciled with the geodetic data. However, thermodynamic modeling, in conjunction with inferences of the nearly constant uplift rates, suggest that the deformations associated with the intrusion emplacement must involve a significant inelastic component. Such inelastic

Water Storage Changes using Floodplain Bathymetry from InSAR and satellite altimetry in the Congo River Basin

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Yuan, T.; Lee, H.; Jung, H. C.; Beighley, E.; Alsdorf, D. E.

2016-12-01

Extensive wetlands and swamps expand along the Congo River and its tributaries. These wetlands store water and attenuate flood wave during high water season. Substantial dissolved and solid substances are also transported with the water flux, influencing geochemical environment and biogeochemistry processes both in the wetlands and the river. To understand the role of the wetlands in partitioning the surface water and the accompanied material movement, water storage change is one of the most fundamental observations. The water flow through the wetlands is complex, affected by topography, vegetation resistance, and hydraulic variations. Interferometric Synthetic Aperture Radar (InSAR) has been successfully used to map relative water level changes in the vegetated wetlands with high spatial resolution. By examining interferograms generated from ALOS PALSAR along the middle reach of the Congo River floodplain, we found greater water level changes near the Congo mainstem. Integrated analysis of InSAR and Envisat altimetry data has shown that proximal floodplain with higher water level change has lower elevation during dry season. This indicates that the spatial variation of water level change in the Congo floodplain is mostly controlled by floodplain bathymetry. A method based on water level and bathymetry model is proposed to estimate water storage change. The bathymetry model is composed of (1) elevation at the intersection of the floodplain and the river and (2) floodplain bathymetry slope. We first constructed the floodplain bathymetry by selecting an Envisat altimetry profile during low water season to estimate elevation at the intersection of the floodplain and the river. Floodplain bathymetry slope was estimated using InSAR measurements. It is expected that our new method can estimate water storage change with higher temporal resolution corresponding to altimeter's repeat cycle. In addition, given the multi-decadal archive of satellite altimetry measurements

Interferometric synthetic aperture radar study of Okmok volcano, Alaska, 1992-2003: Magma supply dynamics and postemplacement lava flow deformation

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Lu, Z.; Masterlark, Timothy; Dzurisin, Daniel

2005-01-01

Okmok volcano, located in the central Aleutian arc, Alaska, is a dominantly basaltic complex topped with a 10-km-wide caldera that formed circa 2.05 ka. Okmok erupted several times during the 20th century, most recently in 1997; eruptions in 1945, 1958, and 1997 produced lava flows within the caldera. We used 80 interferometric synthetic aperture radar (InSAR) images (interferograms) to study transient deformation of the volcano before, during, and after the 1997 eruption. Point source models suggest that a magma reservoir at a depth of 3.2 km below sea level, located beneath the center of the caldera and about 5 km northeast of the 1997 vent, is responsible for observed volcano-wide deformation. The preeruption uplift rate decreased from about 10 cm yr−1 during 1992–1993 to 2 ∼ 3 cm yr−1 during 1993–1995 and then to about −1 ∼ −2 cm yr−1 during 1995–1996. The posteruption inflation rate generally decreased with time during 1997–2001, but increased significantly during 2001–2003. By the summer of 2003, 30 ∼ 60% of the magma volume lost from the reservoir in the 1997 eruption had been replenished. Interferograms for periods before the 1997 eruption indicate consistent subsidence of the surface of the 1958 lava flows, most likely due to thermal contraction. Interferograms for periods after the eruption suggest at least four distinct deformation processes: (1) volcano-wide inflation due to replenishment of the shallow magma reservoir, (2) subsidence of the 1997 lava flows, most likely due to thermal contraction, (3) deformation of the 1958 lava flows due to loading by the 1997 flows, and (4) continuing subsidence of 1958 lava flows buried beneath 1997 flows. Our results provide insights into the postemplacement behavior of lava flows and have cautionary implications for the interpretation of inflation patterns at active volcanoes.

Characterization of open and closed volcanic systems in Indonesia and Mexico using InSAR time series

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Chaussard, E.; Amelung, F.; Aoki, Y.

2013-08-01

use 2007-2011 Advanced Land Observing Satellite (ALOS) data to perform an arc-wide interferometric synthetic aperture radar (InSAR) time series survey of the Trans-Mexican Volcanic Belt (TMVB) and to study time-dependent ground deformation of four Indonesian volcanoes selected following the 2007-2009 study of Chaussard and Amelung (2012). Our objectives are to examine whether arc volcanoes exhibit long-term edifice-wide cyclic deformation patterns that can be used to characterize open and closed volcanic systems and to better constrain in which cases precursory inflation is expected. We reveal deformation cycles at both regularly active and previously inactive Indonesian volcanoes, but we do not detect deformation in the TMVB, reflecting a lower activity level. We identify three types of relationships between deformation and activity: inflation prior to eruption and associated with or followed by deflation (Kerinci and Sinabung), inflation without eruption and followed by slow deflation (Agung), and eruption without precursory deformation (Merapi, Colima, and Popocatépetl; at Merapi, no significant deformation is detected even during eruption). The first two cases correspond to closed volcanic systems and suggest that the traditional model of magmatic systems and eruptive cycles do apply to andesitic volcanoes (i.e., inflation and deflation episodes associated with magma accumulation or volatile exsolution in a crustal reservoir followed by eruptions or in situ cooling). In contrast, the last case corresponds to open volcanic systems where no significant pressurization of the magmatic reservoirs is taking place prior to eruptions and thus no long-term edifice-wide ground deformation can be detected. We discuss these results in terms of InSAR's potential for forecasting volcanic unrest.

Space-Borne and Ground-Based InSAR Data Integration: The Åknes Test Site

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Federica Bardi

2016-03-01

Full Text Available This work concerns a proposal of the integration of InSAR (Interferometric Synthetic Aperture Radar data acquired by ground-based (GB and satellite platforms. The selected test site is the Åknes rockslide, which affects the western Norwegian coast. The availability of GB-InSAR and satellite InSAR data and the accessibility of a wide literature make the landslide suitable for testing the proposed procedure. The first step consists of the organization of a geodatabase, performed in the GIS environment, containing all of the available data. The second step concerns the analysis of satellite and GB-InSAR data, separately. Two datasets, acquired by RADARSAT-2 (related to a period between October 2008 and August 2013 and by a combination of TerraSAR-X and TanDEM-X (acquired between July 2010 and October 2012, both of them in ascending orbit, processed applying SBAS (Small BAseline Subset method, are available. GB-InSAR data related to five different campaigns of measurements, referred to the summer seasons of 2006, 2008, 2009, 2010 and 2012, are available, as well. The third step relies on data integration, performed firstly from a qualitative point of view and later from a semi-quantitative point of view. The results of the proposed procedure have been validated by comparing them to GPS (Global Positioning System data. The proposed procedure allowed us to better define landslide sectors in terms of different ranges of displacements. From a qualitative point of view, stable and unstable areas have been distinguished. In the sector concerning movement, two different sectors have been defined thanks to the results of the semi-quantitative integration step: the first sector, concerning displacement values higher than 10 mm, and the 2nd sector, where the displacements did not exceed a 10-mm value of displacement in the analyzed period.

Analysis of Secular Ground Motions in Istanbul from a Long-Term InSAR Time-Series (1992–2017

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Gokhan Aslan

2018-03-01

Full Text Available The identification and measurement of ground deformations in urban areas is of great importance for determining the vulnerable parts of the cities that are prone to geohazards, which is a crucial element of both sustainable urban planning and hazard mitigation. Interferometric synthetic aperture radar (InSAR time series analysis is a very powerful tool for the operational mapping of ground deformation related to urban subsidence and landslide phenomena. With an analysis spanning almost 25 years of satellite radar observations, we compute an InSAR time series of data from multiple satellites (European Remote Sensing satellites ERS-1 and ERS-2, Envisat, Sentinel-1A, and its twin sensor Sentinel-1B in order to investigate the spatial extent and rate of ground deformation in the megacity of Istanbul. By combining the various multi-track InSAR datasets (291 images in total and analysing persistent scatterers (PS-InSAR, we present mean velocity maps of ground surface displacement in selected areas of Istanbul. We identify several sites along the terrestrial and coastal regions of Istanbul that underwent vertical ground subsidence at varying rates, from 5 ± 1.2 mm/yr to 15 ± 2.1 mm/yr. The results reveal that the most distinctive subsidence patterns are associated with both anthropogenic factors and relatively weak lithologies along the Haramirede valley in particular, where the observed subsidence is up to 10 ± 2 mm/yr. We show that subsidence has been occurring along the Ayamama river stream at a rate of up to 10 ± 1.8 mm/yr since 1992, and has also been slowing down over time following the restoration of the river and stream system. We also identify subsidence at a rate of 8 ± 1.2 mm/yr along the coastal region of Istanbul, which we associate with land reclamation, as well as a very localised subsidence at a rate of 15 ± 2.3 mm/yr starting in 2016 around one of the highest skyscrapers of Istanbul, which was built in 2010.

Tropical-forest biomass estimation at X-Band from the spaceborne TanDEM-X interferometer

Science.gov (United States)

R. Treuhaft; F. Goncalves; J.R. dos Santos; M. Keller; M. Palace; S.N. Madsen; F. Sullivan; P.M.L.A. Graca

2014-01-01

This letter reports the sensitivity of X-band interferometric synthetic aperture radar (InSAR) data from the first dual-spacecraft radar interferometer, TanDEM-X, to variations in tropical-forest aboveground biomass (AGB). It also reports the first tropical-forest AGB estimates fromTanDEM-X data. Tropical forests account for...

On the Design of Radar Corner Reflectors for Deformation Monitoring in Multi-Frequency InSAR

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Matthew C. Garthwaite

2017-06-01

Full Text Available Trihedral corner reflectors are being increasingly used as point targets in deformation monitoring studies using interferometric synthetic aperture radar (InSAR techniques. The frequency and size dependence of the corner reflector Radar Cross Section (RCS means that no single design can perform equally in all the possible imaging modes and radar frequencies available on the currently orbiting Synthetic Aperture Radar (SAR satellites. Therefore, either a corner reflector design tailored to a specific data type or a compromise design for multiple data types is required. In this paper, I outline the practical and theoretical considerations that need to be made when designing appropriate radar targets, with a focus on supporting multi-frequency SAR data. These considerations are tested by performing field experiments on targets of different size using SAR images from TerraSAR-X, COSMO-SkyMed and RADARSAT-2. Phase noise behaviour in SAR images can be estimated by measuring the Signal-to-Clutter ratio (SCR in individual SAR images. The measured SCR of a point target is dependent on its RCS performance and the influence of clutter near to the deployed target. The SCR is used as a metric to estimate the expected InSAR displacement error incurred by the design of each target and to validate these observations against theoretical expectations. I find that triangular trihedral corner reflectors as small as 1 m in dimension can achieve a displacement error magnitude of a tenth of a millimetre or less in medium-resolution X-band data. Much larger corner reflectors (2.5 m or greater are required to achieve the same displacement error magnitude in medium-resolution C-band data. Compromise designs should aim to satisfy the requirements of the lowest SAR frequency to be used, providing that these targets will not saturate the sensor of the highest frequency to be used. Finally, accurate boresight alignment of the corner reflector can be critical to the overall

Separating volcanic deformation and atmospheric signals at Mount St. Helens using Persistent Scatterer InSAR

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Welch, Mark D.; Schmidt, David A.

2017-09-01

Over the past two decades, GPS and leveling surveys have recorded cycles of inflation and deflation associated with dome building eruptions at Mount St. Helens. Due to spatial and temporal limitations of the data, it remains unknown whether any deformation occurred prior to the most recent eruption of 2004, information which could help anticipate future eruptions. Interferometric Synthetic Aperture Radar (InSAR), which boasts fine spatial resolution over large areas, has the potential to resolve pre-eruptive deformation that may have occurred, but eluded detection by campaign GPS surveys because it was localized to the edifice or crater. Traditional InSAR methods are challenging to apply in the Cascades volcanic arc because of a combination of environmental factors, and past attempts to observe deformation at Mount St. Helens were unable to make reliable observations in the crater or on much of the edifice. In this study, Persistent Scatterer InSAR, known to mitigate issues of decorrelation caused by environmental factors, is applied to four SAR data sets in an attempt to resolve localized sources of deformation on the volcano between 1995 and 2010. Many interferograms are strongly influenced by phase delay from atmospheric water vapor and require correction, evidenced by a correlation between phase and topography. To assess the bias imposed by the atmosphere, we perform sensitivity tests on a suite of atmospheric correction techniques, including several that rely on the correlation of phase delay to elevation, and explore approaches that directly estimate phase delay using the ERA-Interim and NARR climate reanalysis data sets. We find that different correction methods produce velocities on the edifice of Mount St. Helens that differ by up to 1 cm/yr due to variability in how atmospheric artifacts are treated in individual interferograms. Additionally, simple phase-based techniques run the risk of minimizing any surface deformation signals that may themselves be

In-situ data collection for oil palm tree height determination using synthetic aperture radar

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Pohl, C.; Loong, C. K.

2016-04-01

The oil palm is recognized as the “golden crop,” producing the highest oil yield among oil seed crops. Malaysia, the world's second largest producer of palm oil, has 16 per cent of its territory planted with oil palms. To cope with the increasing global demand on edible oil, additional areas of oil palm are forecast to increase globally by 12 to 19 million hectares by 2050. Due to the limited land bank in Malaysia, new strategies have to be developed to avoid unauthorized clearing of primary forest for the use of oil palm cultivation. Microwave remote sensing could play a part by providing relevant, timely and accurate information for a plantation monitoring system. The use of synthetic aperture radar (SAR) has the advantage of daylight- and weather-independence, a criterion that is very relevant in constantly cloud-covered tropical regions, such as Malaysia. Using interferometric SAR, (InSAR) topographical and tree height profiles of oil palm plantations can be created; such information is useful for mapping oil palm age profiles of the plantations in the country. This paper reports on the use of SAR and InSAR in a multisensory context to provide up-to-date information at plantation level. Remote sensing and in-situ data collection for tree height determination are described. Further research to be carried out over the next two years is outlined.

An empirical InSAR-optical fusion approach to mapping vegetation canopy height

Science.gov (United States)

Wayne S. Walker; Josef M. Kellndorfer; Elizabeth LaPoint; Michael Hoppus; James Westfall

2007-01-01

Exploiting synergies afforded by a host of recently available national-scale data sets derived from interferometric synthetic aperture radar (InSAR) and passive optical remote sensing, this paper describes the development of a novel empirical approach for the provision of regional- to continental-scale estimates of vegetation canopy height. Supported by data from the...

Temporal Evolution of Surface Deformation and Magma Sources at Pacaya Volcano, Guatemala Revealed by InSAR

Science.gov (United States)

Wnuk, K.; Wauthier, C.

2016-12-01

Pacaya Volcano, Guatemala is a persistently active volcano whose western flank is unstable. Despite continuous activity since 1961, a lack of high temporal resolution geodetic surveying has prevented detailed modeling of Pacaya's underlying magmatic plumbing system. A new, temporally dense dataset of Interferometric Synthetic Aperture Radar (InSAR) RADARSAT-2 images, spanning December 2012 to March 2014, shows magmatic deformation before and during major eruptions in January and March 2014. Inverse modeling of InSAR surface displacements suggest that three magma bodies are responsible for observed deformation: (1) a 3.7 km deep spherical reservoir located northwest of the summit, (2) a 0.4 km deep spherical source located directly west of the summit, and (3) a shallow dike below the summit that provides the primary transport pathway for erupted materials. Periods of heightened activity are brought on by magma pulses at depth, which result in rapid inflation of the edifice. We observe an intrusion cycle at Pacaya that consists of deflation of one or both magma reservoirs followed by dike intrusion. Intrusion volumes are proportional to reservoir volume loss, and do not always result in an eruption. Periods of increased activity culminate with larger dike fed eruptions. Large eruptions are followed by inter eruptive periods marked by a decrease in crater explosions and a lack of deformation. A full understanding of magmatic processes at Pacaya is required to assess potential impacts on other aspects of the volcano such as the unstable western flank. Co-eruptive flank motion appears to have initiated a new stage of volcanic rifting at Pacaya defined by repeated NW-SE dike intrusions. This creates a positive feedback relationship whereby magmatic forcing from eruptive dike intrusions induces flank motion

New formulation for interferometric synthetic aperture radar for terrain mapping

Science.gov (United States)

Jakowatz, Charles V., Jr.; Wahl, Daniel E.; Eichel, Paul H.; Thompson, Paul A.

1994-06-01

The subject of interferometric synthetic aperture radar (IFSAR) for high-accuracy terrain elevation mapping continues to gain importance in the arena of radar signal processing. Applications to problems in precision terrain-aided guidance and automatic target recognition, as well as a variety of civil applications, are being studied by a number of researchers. Not unlike many other areas of SAR processing, the subject of IFSAR can, at first glance, appear to be somewhat mysterious. In this paper we show how the mathematics of IFSAR for terrain elevation mapping using a pair of spotlight mode SAR collections can be derived in a very straightforward manner. Here, we employ an approach that relies entirely on Fourier transforms, and utilizes no reference to range equations or Doppler concepts. The result is a simplified explanation of the fundamentals of interferometry, including an easily-seen link between image domain phase difference and terrain elevation height. The derivation builds upon previous work by the authors in which a framework for spotlight mode SAR image formation based on an analogy to 3D computerized axial tomography (CAT) was developed. After outlining the major steps in the mathematics, we show how a computer simulator which utilizes 3D Fourier transforms can be constructed that demonstrates all of the major aspects of IFSAR from spotlight mode collections.

A three-step maximum a posteriori probability method for InSAR data inversion of coseismic rupture with application to the 14 April 2010 Mw 6.9 Yushu, China, earthquake

Science.gov (United States)

Sun, Jianbao; Shen, Zheng-Kang; Bürgmann, Roland; Wang, Min; Chen, Lichun; Xu, Xiwei

2013-08-01

develop a three-step maximum a posteriori probability method for coseismic rupture inversion, which aims at maximizing the a posterior probability density function (PDF) of elastic deformation solutions of earthquake rupture. The method originates from the fully Bayesian inversion and mixed linear-nonlinear Bayesian inversion methods and shares the same posterior PDF with them, while overcoming difficulties with convergence when large numbers of low-quality data are used and greatly improving the convergence rate using optimization procedures. A highly efficient global optimization algorithm, adaptive simulated annealing, is used to search for the maximum of a posterior PDF ("mode" in statistics) in the first step. The second step inversion approaches the "true" solution further using the Monte Carlo inversion technique with positivity constraints, with all parameters obtained from the first step as the initial solution. Then slip artifacts are eliminated from slip models in the third step using the same procedure of the second step, with fixed fault geometry parameters. We first design a fault model with 45° dip angle and oblique slip, and produce corresponding synthetic interferometric synthetic aperture radar (InSAR) data sets to validate the reliability and efficiency of the new method. We then apply this method to InSAR data inversion for the coseismic slip distribution of the 14 April 2010 Mw 6.9 Yushu, China earthquake. Our preferred slip model is composed of three segments with most of the slip occurring within 15 km depth and the maximum slip reaches 1.38 m at the surface. The seismic moment released is estimated to be 2.32e+19 Nm, consistent with the seismic estimate of 2.50e+19 Nm.

A portfolio of products from the rapid terrain visualization interferometric SAR

Science.gov (United States)

Bickel, Douglas L.; Doerry, Armin W.

2007-04-01

The Rapid Terrain Visualization interferometric synthetic aperture radar was designed and built at Sandia National Laboratories as part of an Advanced Concept Technology Demonstration (ACTD) to "demonstrate the technologies and infrastructure to meet the Army requirement for rapid generation of digital topographic data to support emerging crisis or contingencies." This sensor was built by Sandia National Laboratories for the Joint Programs Sustainment and Development (JPSD) Project Office to provide highly accurate digital elevation models (DEMs) for military and civilian customers, both inside and outside of the United States. The sensor achieved better than HRTe Level IV position accuracy in near real-time. The system was flown on a deHavilland DHC-7 Army aircraft. This paper presents a collection of images and data products from the Rapid Terrain Visualization interferometric synthetic aperture radar. The imagery includes orthorectified images and DEMs from the RTV interferometric SAR radar.

GBIS (Geodetic Bayesian Inversion Software): Rapid Inversion of InSAR and GNSS Data to Estimate Surface Deformation Source Parameters and Uncertainties

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Bagnardi, M.; Hooper, A. J.

2017-12-01

Inversions of geodetic observational data, such as Interferometric Synthetic Aperture Radar (InSAR) and Global Navigation Satellite System (GNSS) measurements, are often performed to obtain information about the source of surface displacements. Inverse problem theory has been applied to study magmatic processes, the earthquake cycle, and other phenomena that cause deformation of the Earth's interior and of its surface. Together with increasing improvements in data resolution, both spatial and temporal, new satellite missions (e.g., European Commission's Sentinel-1 satellites) are providing the unprecedented opportunity to access space-geodetic data within hours from their acquisition. To truly take advantage of these opportunities we must become able to interpret geodetic data in a rapid and robust manner. Here we present the open-source Geodetic Bayesian Inversion Software (GBIS; available for download at http://comet.nerc.ac.uk/gbis). GBIS is written in Matlab and offers a series of user-friendly and interactive pre- and post-processing tools. For example, an interactive function has been developed to estimate the characteristics of noise in InSAR data by calculating the experimental semi-variogram. The inversion software uses a Markov-chain Monte Carlo algorithm, incorporating the Metropolis-Hastings algorithm with adaptive step size, to efficiently sample the posterior probability distribution of the different source parameters. The probabilistic Bayesian approach allows the user to retrieve estimates of the optimal (best-fitting) deformation source parameters together with the associated uncertainties produced by errors in the data (and by scaling, errors in the model). The current version of GBIS (V1.0) includes fast analytical forward models for magmatic sources of different geometry (e.g., point source, finite spherical source, prolate spheroid source, penny-shaped sill-like source, and dipping-dike with uniform opening) and for dipping faults with uniform

Benefits and limitations of imaging multiples: Interferometric and resonant migration

KAUST Repository

Guo, Bowen

2015-07-01

The benefits and limitations of imaging multiples are reviewed for interferometric migration and resonant migration. Synthetic and field data examples are used to characterize the effectiveness of the methods.

Benefits and limitations of imaging multiples: Interferometric and resonant migration

KAUST Repository

Guo, Bowen; Yu, Jianhua; Huang, Yunsong; Hanafy, Sherif M.; Schuster, Gerard T.

2015-01-01

The benefits and limitations of imaging multiples are reviewed for interferometric migration and resonant migration. Synthetic and field data examples are used to characterize the effectiveness of the methods.

Application of InSAR to detection of localized subsidence and its effects on flood protection infrastructure in the New Orleans area

Science.gov (United States)

Jones, Cathleen; Blom, Ronald; Latini, Daniele

2014-05-01

The vulnerability of the United States Gulf of Mexico coast to inundation has received increasing attention in the years since hurricanes Katrina and Rita. Flood protection is a challenge throughout the area, but the population density and cumulative effect of historic subsidence makes it particularly difficult in the New Orleans area. Analysis of historical and continuing geodetic measurements identifies a surprising degree of complexity in subsidence (Dokka 2011), including regions that are subsiding at rates faster than those considered during planning for hurricane protection and for coastal restoration projects. Improved measurements are possible through combining traditional single point, precise geodetic data with interferometric synthetic aperture radar (InSAR) observations for to obtain geographically dense constraints on surface deformation. The Gulf Coast environment is very challenging for InSAR techniques, especially with systems not designed for interferometry. We are applying pair-wise InSAR to longer wavelength (L-band, 24 cm) synthetic aperture radar data acquired with the airborne UAVSAR instrument (http://uavsar.jpl.nasa.gov/) to detect localized change impacting flood protection infrastructure in the New Orleans area during the period from 2009 - 2013. Because aircraft motion creates large-scale image artifacts across the scene, we focus on localized areas on and near flood protection infrastructure to identify anomalous change relative to the surrounding area indicative of subsidence, structural deformation, and/or seepage (Jones et al., 2011) to identify areas where problems exist. C-band and particularly X-band radar returns decorrelate over short time periods in rural or less urbanized areas and are more sensitive to atmospheric affects, necessitating more elaborate analysis techniques or, at least, a strict limit on the temporal baseline. The new generation of spaceborne X-band SAR acquisitions ensure relatively high frequency of

Assessing groundwater depletion and dynamics using GRACE and InSAR: Potential and limitations

Science.gov (United States)

Castellazzi, Pascal; Martel, Richard; Galloway, Devin L.; Longuevergne, Laurent; Rivera, Alfonso

2016-01-01

In the last decade, remote sensing of the temporal variation of ground level and gravity has improved our understanding of groundwater dynamics and storage. Mass changes are measured by GRACE (Gravity Recovery and Climate Experiment) satellites, whereas ground deformation is measured by processing synthetic aperture radar satellites data using the InSAR (Interferometry of Synthetic Aperture Radar) techniques. Both methods are complementary and offer different sensitivities to aquifer system processes. GRACE is sensitive to mass changes over large spatial scales (more than 100,000 km2). As such, it fails in providing groundwater storage change estimates at local or regional scales relevant to most aquifer systems, and at which most groundwater management schemes are applied. However, InSAR measures ground displacement due to aquifer response to fluid-pressure changes. InSAR applications to groundwater depletion assessments are limited to aquifer systems susceptible to measurable deformation. Furthermore, the inversion of InSAR-derived displacement maps into volume of depleted groundwater storage (both reversible and largely irreversible) is confounded by vertical and horizontal variability of sediment compressibility. During the last decade, both techniques have shown increasing interest in the scientific community to complement available in situ observations where they are insufficient. In this review, we present the theoretical and conceptual bases of each method, and present idealized scenarios to highlight the potential benefits and challenges of combining these techniques to remotely assess groundwater storage changes and other aspects of the dynamics of aquifer systems.

From Regional Hazard Assessment to Nuclear-Test-Ban Treaty Support - InSAR Ground Motion Services

Science.gov (United States)

Lege, T.; Kalia, A.; Gruenberg, I.; Frei, M.

2016-12-01

There are numerous scientific applications of InSAR methods in tectonics, earthquake analysis and other geologic and geophysical fields. Ground motion on local and regional scale measured and monitored via the application of the InSAR techniques provide scientists and engineers with plenty of new insights and further understanding of subsurface processes. However, the operational use of InSAR is not yet very widespread. To foster the operational utilization of the Copernicus Sentinel Satellites in the day-to-day business of federal, state and municipal work and planning BGR (Federal Institute for Geosciences and Natural Resources) initiated workshops with potential user groups. Through extensive reconcilement of interests and demands with scientific, technical, economic and governmental stakeholders (e.g. Ministries, Mining Authorities, Geological Surveys, Geodetic Surveys and Environmental Agencies on federal and state level, SMEs, German Aerospace Center) BGR developed the concept of the InSAR based German National Ground Motion Service. One important backbone for the nationwide ground motion service is the so-called Persistent Scatterer Interferometry Wide Area Product (WAP) approach developed with grants of European research funds. The presentation shows the implementation of the ground motion service and examples for product developments for operational supervision of mining, water resources management and spatial planning. Furthermore the contributions of Copernicus Sentinel 1 radar data in the context of CTBT are discussed. The DInSAR processing of Sentinel 1 IW (Interferometric Wide Swath) SAR acquisitions from January 1st and 13th Jan. 2016 allow for the first time a near real time ground motion measurement of the North Korean nuclear test site. The measured ground displacements show a strong spatio-temporal correlation to the calculated epicenter measured by teleseismic stations. We are convinced this way another space technique will soon contribute even

Mechanical properties of conjugate faults in the Makran accretionary prism estimated from InSAR observations of coseismic deformation due to the 2013 Baluchistan (Mw 7.7) earthquake

Science.gov (United States)

Dutta, R.; Harrington, J.; Wang, T.; Feng, G.; Vasyura-Bathke, H.; Jonsson, S.

2017-12-01

Interferometric Synthetic Aperture Radar (InSAR) measurements allow us to study various mechanical and rheological properties around faults. For example, strain localizations along faults induced by nearby earthquakes observed by InSAR have been explained by the elastic response of compliant fault zones (CFZ) where the elastic moduli is reduced with respect to that of the surrounding rock. We observed similar strain localizations (up to 1-3 cm displacements in the line-of-sight direction of InSAR) along several conjugate faults near the rupture of the 2013 Mw7.7 Baluchistan (Pakistan) earthquake in the accretionary prism of the Makran subduction zone. These conjugate compliant faults, which have strikes of N30°E and N45°W, are located 15-30 km from the mainshock fault rupture in a N-S compressional stress regime. The long-term geologic slip direction of these faults is left-lateral for the N30°E striking faults and right-lateral for the N45°W striking faults. The 2013 Baluchistan earthquake caused WSW-ENE extensional coseismic stress changes across the conjugate fault system and the observed strain localizations shows opposite sense of motion to that of the geologic long-term slip. We use 3D Finite Element modeling (FEM) to study the effects extensional coseismic stresses have on the conjugate CFZs that is otherwise loaded in a compressional regional stress. We use coseismic static displacements due to the earthquake along the FEM domain boundaries to simulate the extensional coseismic stress change acting across the fault system. Around 0.5-2 km wide CFZs with reduction in shear modulus by a factor of 3 to 4 can explain the observed InSAR strain localizations and the opposite sense of motion. The InSAR measurements were also used to constrain the ranges of the length, width and rigidity variations of the CFZs. The FEM solution shows that the N45°W striking faults localize mostly extensional strain and a small amount of left-lateral shear (opposite sense to

Interferometric interpolation of sparse marine data

KAUST Repository

Hanafy, Sherif M.

2013-10-11

We present the theory and numerical results for interferometrically interpolating 2D and 3D marine surface seismic profiles data. For the interpolation of seismic data we use the combination of a recorded Green\\'s function and a model-based Green\\'s function for a water-layer model. Synthetic (2D and 3D) and field (2D) results show that the seismic data with sparse receiver intervals can be accurately interpolated to smaller intervals using multiples in the data. An up- and downgoing separation of both recorded and model-based Green\\'s functions can help in minimizing artefacts in a virtual shot gather. If the up- and downgoing separation is not possible, noticeable artefacts will be generated in the virtual shot gather. As a partial remedy we iteratively use a non-stationary 1D multi-channel matching filter with the interpolated data. Results suggest that a sparse marine seismic survey can yield more information about reflectors if traces are interpolated by interferometry. Comparing our results to those of f-k interpolation shows that the synthetic example gives comparable results while the field example shows better interpolation quality for the interferometric method. © 2013 European Association of Geoscientists & Engineers.

Post-Eruption Deformation Processes Measured Using ALOS-1 and UAVSAR InSAR at Pacaya Volcano, Guatemala

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Lauren N. Schaefer

2016-01-01

Full Text Available Pacaya volcano is a persistently active basaltic cone complex located in the Central American Volcanic Arc in Guatemala. In May of 2010, violent Volcanic Explosivity Index-3 (VEI-3 eruptions caused significant topographic changes to the edifice, including a linear collapse feature 600 m long originating from the summit, the dispersion of ~20 cm of tephra and ash on the cone, the emplacement of a 5.4 km long lava flow, and ~3 m of co-eruptive movement of the southwest flank. For this study, Interferometric Synthetic Aperture Radar (InSAR images (interferograms processed from both spaceborne Advanced Land Observing Satellite-1 (ALOS-1 and aerial Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR data acquired between 31 May 2010 and 10 April 2014 were used to measure post-eruptive deformation events. Interferograms suggest three distinct deformation processes after the May 2010 eruptions, including: (1 subsidence of the area involved in the co-eruptive slope movement; (2 localized deformation near the summit; and (3 emplacement and subsequent subsidence of about a 5.4 km lava flow. The detection of several different geophysical signals emphasizes the utility of measuring volcanic deformation using remote sensing techniques with broad spatial coverage. Additionally, the high spatial resolution of UAVSAR has proven to be an excellent compliment to satellite data, particularly for constraining motion components. Measuring the rapid initiation and cessation of flank instability, followed by stabilization and subsequent influence on eruptive features, provides a rare glimpse into volcanic slope stability processes. Observing these and other deformation events contributes both to hazard assessment at Pacaya and to the study of the stability of stratovolcanoes.

Land Subsidence Monitoring by InSAR Time Series Technique Derived From ALOS-2 PALSAR-2 over Surabaya City, Indonesia

Science.gov (United States)

Aditiya, A.; Takeuchi, W.; Aoki, Y.

2017-12-01

Surabaya is the second largest city in Indonesia and the capital of East Java Province with rapid population and industrialization. The impact of urbanization in the big city can suffer potential disasters either nature or anthropogenic such as land subsidence and flood. The pattern of land subsidence need to be mapped for the purposes of planning and structuring the city as well as taking appropriate policy in anticipating and mitigating the impact. This research has used interferometric Synthetic Aperture Radar (InSAR) Small Baseline Subset (SBAS) technique and applied time series analysis to investigate land subsidence occured. The technique includes the process of focusing the SAR data, incorporating the precise orbit, generating interferogram and phase unwrapping using SNAPHU algorithms. The results showed land subsidence has been detected during 2014-2017 over Surabaya city area using ALOS-2/PALSAR-2 images data. These results reveal the subsidence has observed in several area in Surabaya in particular northern part reach up to ∼2 cm/year. The fastest subsidence occurs in highly populated areas suffer vulnerable to flooding and sea level rise impact. In urban areas we found a correlation between land subsidence with residential or industrial land use. It concludes that land subsidence is mainly caused by ground water consumption for industrial and residential use respectively.

Characterizing and estimating noise in InSAR and InSAR time series with MODIS

Science.gov (United States)

Barnhart, William D.; Lohman, Rowena B.

2013-01-01

InSAR time series analysis is increasingly used to image subcentimeter displacement rates of the ground surface. The precision of InSAR observations is often affected by several noise sources, including spatially correlated noise from the turbulent atmosphere. Under ideal scenarios, InSAR time series techniques can substantially mitigate these effects; however, in practice the temporal distribution of InSAR acquisitions over much of the world exhibit seasonal biases, long temporal gaps, and insufficient acquisitions to confidently obtain the precisions desired for tectonic research. Here, we introduce a technique for constraining the magnitude of errors expected from atmospheric phase delays on the ground displacement rates inferred from an InSAR time series using independent observations of precipitable water vapor from MODIS. We implement a Monte Carlo error estimation technique based on multiple (100+) MODIS-based time series that sample date ranges close to the acquisitions times of the available SAR imagery. This stochastic approach allows evaluation of the significance of signals present in the final time series product, in particular their correlation with topography and seasonality. We find that topographically correlated noise in individual interferograms is not spatially stationary, even over short-spatial scales (<10 km). Overall, MODIS-inferred displacements and velocities exhibit errors of similar magnitude to the variability within an InSAR time series. We examine the MODIS-based confidence bounds in regions with a range of inferred displacement rates, and find we are capable of resolving velocities as low as 1.5 mm/yr with uncertainties increasing to ∼6 mm/yr in regions with higher topographic relief.

InSAR Observations and Finite Element Modeling of Crustal Deformation Around a Surging Glacier, Iceland

Science.gov (United States)

Spaans, K.; Auriac, A.; Sigmundsson, F.; Hooper, A. J.; Bjornsson, H.; Pálsson, F.; Pinel, V.; Feigl, K. L.

2014-12-01

Icelandic ice caps, covering ~11% of the country, are known to be surging glaciers. Such process implies an important local crustal subsidence due to the large ice mass being transported to the ice edge during the surge in a few months only. In 1993-1995, a glacial surge occurred at four neighboring outlet glaciers in the southwestern part of Vatnajökull ice cap, the largest ice cap in Iceland. We estimated that ~16±1 km3 of ice have been moved during this event while the fronts of some of the outlet glaciers advanced by ~1 km.Surface deformation associated with this surge has been surveyed using Interferometric Synthetic Aperture Radar (InSAR) acquisitions from 1992-2002, providing high resolution ground observations of the study area. The data show about 75 mm subsidence at the ice edge of the outlet glaciers following the transport of the large volume of ice during the surge (Fig. 1). The long time span covered by the InSAR images enabled us to remove ~12 mm/yr of uplift occurring in this area due to glacial isostatic adjustment from the retreat of Vatnajökull ice cap since the end of the Little Ice Age in Iceland. We then used finite element modeling to investigate the elastic Earth response to the surge, as well as confirm that no significant viscoelastic deformation occurred as a consequence of the surge. A statistical approach based on Bayes' rule was used to compare the models to the observations and obtain an estimate of the Young's modulus (E) and Poisson's ratio (v) in Iceland. The best-fitting models are those using a one-kilometer thick top layer with v=0.17 and E between 12.9-15.3 GPa underlain by a layer with v=0.25 and E from 67.3 to 81.9 GPa. Results demonstrate that InSAR data and finite element models can be used successfully to reproduce crustal deformation induced by ice mass variations at Icelandic ice caps.Fig. 1: Interferograms spanning 1993 July 31 to 1995 June 19, showing the surge at Tungnaárjökull (Tu.), Skaftárjökull (Sk.) and S�

Pyroclastic Flow Deposits and InSAR: Analysis of Long-Term Subsidence at Augustine Volcano, Alaska

Directory of Open Access Journals (Sweden)

David B. McAlpin

2016-12-01

Full Text Available Deformation of pyroclastic flow deposits begins almost immediately after emplacement, and continues thereafter for months or years. This study analyzes the extent, volume, thickness, and variability in pyroclastic flow deposits (PFDs on Augustine Volcano from measuring their deformation rates with interferometric synthetic aperture radar (InSAR. To conduct this analysis, we obtained 48 SAR images of Augustine Volcano acquired between 1992 and 2010, spanning its most recent eruption in 2006. The data were processed using d-InSAR time-series analysis to measure the thickness of the Augustine PFDs, as well as their surface deformation behavior. Because much of the 2006 PFDs overlie those from the previous eruption in 1986, geophysical models were derived to decompose deformation contributions from the 1986 deposits underlying the measured 2006 deposits. To accomplish this, we introduce an inversion approach to estimate geophysical parameters for both 1986 and 2006 PFDs. Our analyses estimate the expanded volume of pyroclastic flow material deposited during the 2006 eruption to be 3.3 × 107 m3 ± 0.11 × 107 m3, and that PFDs in the northeastern part of Augustine Island reached a maximum thickness of ~31 m with a mean of ~5 m. Similarly, we estimate the expanded volume of PFDs from the 1986 eruption at 4.6 × 107 m3 ± 0.62 × 107 m3, with a maximum thickness of ~31 m, and a mean of ~7 m.

MAPPING THE EXTENT AND MAGNITUDE OF SEVER FLOODING INDUCED BY HURRICANE IRMA WITH MULTI-TEMPORAL SENTINEL-1 SAR AND INSAR OBSERVATIONS

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B. Zhang

2018-04-01

Full Text Available During Hurricane Irma’s passage over Florida in September 2017, many sections of the state experienced heavy rain and sequent flooding. In order to drain water out of potential flooding zones and assess property damage, it is important to map the extent and magnitude of the flooded areas at various stages of the storm. We use Synthetic Aperture Radar (SAR and Interferometric SAR (InSAR observations, acquired by Sentinel-1 before, during and after the hurricane passage, which enable us to evaluate surface condition during different stages of the hurricane. This study uses multi-temporal images acquired under dry condition before the hurricane to constrain the background backscattering signature. Flooded areas are detected when the backscattering during the hurricane is statistically significantly different from the average dry conditions. The detected changes can be either an increase or decrease of the backscattering, which depends on the scattering characteristics of the surface. In addition, water level change information in Palmdale, South Florida is extracted from an interferogram with the aid of a local water gauge as the reference. The results of our flooding analysis revealed that the majority of the study area in South Florida was flooded during Hurricane Irma.

InSAR and GPS derived coseismic deformation and fault model of the 2017 Ms7.0 Jiuzhaigou earthquake in the Northeast Bayanhar block

Science.gov (United States)

Zhao, Dezheng; Qu, Chunyan; Shan, Xinjian; Gong, Wenyu; Zhang, Yingfeng; Zhang, Guohong

2018-02-01

On 8 August 2017, a Ms7.0 earthquake stroke the city of Jiuzhaigou, Sichuan, China. The Jiuzhaigou earthquake occurred on a buried fault in the vicinity of three well-known active faults and this event offers a unique opportunity to study tectonic structures in the epicentral region and stress transferring. Here we present coseismic displacement field maps for this earthquake using descending and ascending Sentinel-1A Interferometric Synthetic Aperture Radar (InSAR) data. Deformation covered an area of approximately 50 × 50 km, with a maximum line-of-sight (LOS) displacement of 22 cm in ascending and 14 cm in descending observations on the west side of the source fault. Based on InSAR and Global Positioning System (GPS) measurements, both separately and jointly, we constructed a one-segment model to invert the coseismic slip distribution and dip angle of this event. Our final fault slip model suggests that slip was concentrated at an upper depth of 15 km; there was a maximum slip of 1.3 m and the rupture was dominated by a left-lateral strike-slip motion. The inverted geodetic moment was approximately 6.75 × 1018 Nm, corresponding to a moment magnitude of Mw6.5, consistent with seismological results. The calculated static Coulomb stress changes indicate that most aftershocks occurred in stress increasing zones caused by the mainshock rupture; the Jiuzhaigou earthquake has brought the western part of the Tazang fault 0.1-0.4 MPa closer to failure, indicating an increasing seismic hazard in this region. The Coulomb stress changes caused by the 2008 Mw7.8 Wenchuan earthquake suggest that stress loading from this event acted as a trigger for the Jiuzhaigou earthquake.

On the use of InSAR technology to assess land subsidence in Jakarta coastal flood plain

Science.gov (United States)

Koudogbo, Fifame; Duro, Javier; Garcia Robles, Javier; Arnaud, Alain; Abidin, Hasanuddin Z.

2014-05-01

Jakarta is the capital of Indonesia and is home to approximately 10 million people on the coast of the Java Sea. It is situated on the northern coastal alluvial plane of Java which shares boundaries with West Java Province in the south and in the east, and with Banten Province in the west. The Capital District of Jakarta (DKI) sits in the lowest lying areas of the basin. Its topography varies, with the northern part just meters above current sea level and lying on a flood plain. Subsequently, this portion of the city frequently floods. The southern part of the city is hilly. Thirteen major rivers flow through Jakarta to the Java Sea. The Ciliwung River is the most significant river and divides the city West to East. In the last three decades, urban growing of Jakarta has been very fast in sectors as industry, trade, transportation, real estate, among others. This exponential development has caused several environmental issues; land subsidence is one of them. Subsidence in Jakarta has been known since the early part of the 20th century. It is mainly due to groundwater extraction, the fast development (construction load), soil natural consolidation and tectonics. Evidence of land subsidence exists through monitoring with GPS, level surveys and InSAR investigations. InSAR states for "Interferometric Synthetic Aperture Radar". Its principle is based on comparing the distance between the satellite and the ground in consecutive satellite passes over the same area on the Earth's surface. Radar satellites images record, with very high precision, the distance travelled by the radar signal that is emitted by the satellite is registered. When this distance is compared through time, InSAR technology can provide highly accurate ground deformation measurements. ALTAMIRA INFORMATION, company specialized in ground motion monitoring, has developed GlobalSARTM, which combines several processing techniques and algorithms based on InSAR technology, to achieve ground motion

Toward regional corrections of long period CMT inversions using InSAR

Science.gov (United States)

Shakibay Senobari, N.; Funning, G.; Ferreira, A. M.

2017-12-01

One of InSAR's main strengths, with respect to other methods of studying earthquakes, is finding the accurate location of the best point source (or `centroid') for an earthquake. While InSAR data have great advantages for study of shallow earthquakes, the number of earthquakes for which we have InSAR data is low, compared with the number of earthquakes recorded seismically. And though improvements to SAR satellite constellations have enhanced the use of InSAR data during earthquake response, post-event data still have a latency on the order of days. On the other hand, earthquake centroid inversion methods using long period seismic data (e.g. the Global CMT method) are fast but include errors caused by inaccuracies in both the Earth velocity model and in wave propagation assumptions (e.g. Hjörleifsdóttir and Ekström, 2010; Ferreira and Woodhouse, 2006). Here we demonstrate a method that combines the strengths of both methods, calculating regional travel-time corrections for long-period waveforms using accurate centroid locations from InSAR, then applying these to other events that occur in the same region. Our method is based on the observation that synthetic seismograms produced from InSAR source models and locations match the data very well except for some phase shifts (travel time biases) between the two waveforms, likely corresponding to inaccuracies in Earth velocity models (Weston et al., 2014). Our previous work shows that adding such phase shifts to the Green's functions can improve the accuracy of long period seismic CMT inversions by reducing tradeoffs between the moment tensor components and centroid location (e.g. Shakibay Senobari et al., AGU Fall Meeting 2015). Preliminary work on several pairs of neighboring events (e.g. Landers-Hector Mine, the 2000 South Iceland earthquake sequences) shows consistent azimuthal patterns of these phase shifts for nearby events at common stations. These phase shift patterns strongly suggest that it is possible to

A system for airborne SAR interferometry

DEFF Research Database (Denmark)

Madsen, Søren Nørvang; Skou, Niels; Granholm, Johan

1996-01-01

Interferometric synthetic aperture radar (INSAR) systems have already demonstrated that elevation maps can be generated rapidly with single pass airborne across-track interferometry systems (XTT), and satellite repeat track interferometry (RTT) techniques have been used to map both elevation...... and perturbations of the surface of the Earth. The Danish Center for Remote Sensing (DCRS) has experimented with airborne INSAR since 1993. Multiple track data are collected in a special mode in which the radar directly steers the aircraft which allows for very precise control of the flight path. Such data sets......) the status of the airborne interferometry activities at DCRS, including the present system configuration, recent results, and some scientific applications of the system....

Mapping the Extent and Magnitude of Severe Flooding Induced by Hurricanes Harvey, Irma, and Maria with Sentinel-1 SAR and InSAR Observations

Science.gov (United States)

Zhang, B.; Koirala, R.; Oliver-Cabrera, T.; Wdowinski, S.; Osmanoglu, B.

2017-12-01

Hurricanes can cause winds, rainfall and storm surge, all of which could result in flooding. Between August and September 2017, Hurricanes Harvey, Irma and Maria made landfall over Texas, Florida and Puerto Rico causing destruction and damages. Flood mapping is important for water management and to estimate risks and property damage. Though water gauges are able to monitor water levels, they are normally distributed sparsely. To map flooding products of these extreme events, we use Synthetic Aperture Radar (SAR) observations acquired by the European satellite constellation Sentinel-1. We obtained two acquisitions from before each flooding event, a single acquisition during the hurricane, and two after each event, a total of five acquisitions. We use both amplitude and phase observations to map extent and magnitude of flooding respectively. To map flooding extents, we use amplitude images from before, after and if possible during the hurricane pass. A calibration is used to convert the image raw data to backscatter coefficient, termed sigma nought. We generate a composite of the two image layers using red and green bands to show the change of sigma nought between acquisitions, which directly reflects the extent of flooding. Because inundation can result with either an increase or decrease of sigma nought values depending on the surface scattering characteristics, we map flooded areas in location where sigma nought changes were above a detection threshold. To study magnitude of flooding we study Interferometric Synthetic Aperture Radar (InSAR) phase changes. Changes in the water level can be detected by the radar when the signal is reflected away from water surface and bounces again by another object (e.g. trees and/or buildings) known as double bounce phase. To generate meaningful interferograms, we compare phase information with the nearest water gauge records to verify our results. Preliminary results show that the three hurricanes caused flooding condition over

Magmatic Activity Beneath the Quiescent Three Sisters Volcanic Center, Central Oregon Cascade Range, USA, Inferred from Satellite InSAR

Science.gov (United States)

Wicks, C. W.; Dzurisin, D.; Ingebritsen, S.; Thatcher, W.; Lu, Z.; Iverson, J.

2001-12-01

Images from satellite interferometric synthetic aperture radar (InSAR) reveal uplift of a broad ~10 km by 20 km area in the Three Sisters volcanic center of the central Oregon Cascade Range, ~130 km south of Mt. St. Helens. The uplift is centered ~5 km west of South Sister volcano, the youngest stratovolcano in the volcanic center. The center has been volcanically inactive since the last eruption ~1500 years ago. Multiple European Space Agency ERS-1 and 2 satellite images from 1992 through 2000, used in this study, were selected based on orbital separation and time of year. Summer and early autumn scenes were necessary to avoid decorrelation from snow cover. Interferograms generated from these images indicate that most if not all of ~100 mm of observed uplift occurred between September 1998 and October 2000. We interpret the uplift as inflation caused by an apparently ongoing episode of magma intrusion at a depth of ~6.5 km. Geochemical (water chemistry) anomalies, first noted ~1990, coincide with the area of uplift and suggest the existence of a magma reservoir prior to the uplift. High chloride and sulfate concentrations, and a positive correlation between chloride concentration and spring temperature were found within the uplift area, with larger SO4/Cl ratios in springs at higher elevations. These findings are indicative of a high-temperature hydrothermal system driven by magma intrusions. The current inflation episode observed with InSAR may lead to an eruption, but the more persistent geochemical evidence suggests that the episode is likely the latest in a series of hitherto undetected magma intrusions. We do not yet know if the inflation has abated, is continuing, or has accelerated since October 2000--we only know that the highest rate of uplift occurred in the last year for which ERS-2 data was available (1999- 2000). In May of 2001, a continuous GPS receiver and seismometer were installed by the USGS within the Three Sisters Wilderness to monitor the

Towards assimilation of InSAR data in operational weather models

Science.gov (United States)

Mulder, Gert; van Leijen, Freek; Barkmeijer, Jan; de Haan, Siebren; Hanssen, Ramon

2017-04-01

based on several case studies. This research can be seen as a first step towards the operational use of InSAR data in state-of-the-art weather models and can be a driver for the design and development for new SAR missions, such as NISAR. References: [1] Hanssen, R. F., Weckwerth, T. M., Zebker, H. A., & Klees, R. (1999). High-resolution water vapor mapping from interferometric radar measurements.Science, 283(5406), 1297-1299. [2] P. Mateus, R. Tomé, G. Nico and J. Catalão, "Three-Dimensional Variational Assimilation of InSAR PWV Using the WRFDA Model," in IEEE Transactions on Geoscience and Remote Sensing, vol. 54, no. 12, pp. 7323-7330, Dec. 2016. [3] Navascués, B., Calvo, J., Morales, G., Santos, C., Callado, A., Cansado, A., ... & García-Colombo, O. (2013). Long-term verification of HIRLAM and ECMWF forecasts over southern europe: History and perspectives of numerical weather prediction at AEMET. Atmospheric Research, 125, 20-33. [4] Seity, Y., P. Brousseau, S. Malardel, G. Hello, P. Bénard, F. Bouttier, C. Lac, and V. Masson, 2011: The AROME-France Convective-Scale Operational Model. Mon. Wea. Rev., 139, 976-991. [5] Lorenc, A. C. and Rawlins, F. (2005), Why does 4D-Var beat 3D-Var?. Q.J.R. Meteorol. Soc., 131: 3247-3257.

3D surface flow kinematics derived from airborne UAVSAR interferometric synthetic aperture radar to constrain the physical mechanisms controlling landslide motion

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Delbridge, B. G.; Burgmann, R.; Fielding, E. J.; Hensley, S.; Schulz, W. H.

2013-12-01

This project focuses on improving our understanding of the physical mechanisms controlling landslide motion by studying the landslide-wide kinematics of the Slumgullion landslide in southwestern Colorado using interferometric synthetic aperture radar (InSAR) and GPS. The NASA/JPL UAVSAR airborne repeat-pass SAR interferometry system imaged the Slumgullion landslide from 4 look directions on eight flights in 2011 and 2012. Combining the four look directions allows us to extract the full 3-D velocity field of the surface. Observing the full 3-dimensional flow field allows us to extract the full strain tensor (assuming free surface boundary conditions and incompressible flow) since we have both the spatial resolution to take spatial derivates and full deformation information. COSMO-SkyMed(CSK) high-resolution Spotlight data was also acquired during time intervals overlapping with the UAVSAR one-week pairs, with intervals as short as one day. These observations allow for the quantitative testing of the deformation magnitude and estimated formal errors in the UAVSAR derived deformation field. We also test the agreement of the deformation at 20 GPS monitoring sites concurrently acquired by the USGS. We also utilize the temporal resolution of real-time GPS acquired by the UC Berkeley Active Tectonics Group during a temporary deployment from July 22nd - August 2nd. By combining this data with the kinematic data we hope to elucidate the response of the landslide to environmental changes such as rainfall, snowmelt, and atmospheric pressure, and consequently the mechanisms controlling the dynamics of the landslide system. To constrain the longer temporal dynamics, interferograms made from pairs of CSK images acquired in 2010, 2011, 2012 and 2013 reveal the slide deformation on a longer timescale by allowing us to measure meters of motion and see the average rates over year long intervals using pixel offset tracking of the high-resolution SAR amplitude images. The results of

Mapping tectonic and anthropogenic processes in central California using satellite and airborne InSAR

Science.gov (United States)

Liu, Z.; Lundgren, P.; Liang, C.; Farr, T. G.; Fielding, E. J.

2017-12-01

The improved spatiotemporal resolution of surface deformation from recent satellite and airborne InSAR measurements provides a great opportunity to improve our understanding of both tectonic and non-tectonic processes. In central California the primary plate boundary fault system (San Andreas fault) lies adjacent to the San Joaquin Valley (SJV), a vast structural trough that accounts for about one-sixth of the United Sates' irrigated land and one-fifth of its extracted groundwater. The central San Andreas fault (CSAF) displays a range of fault slip behavior with creeping in its central segment that decreases towards its northwest and southeast ends, where it transitions to being fully locked. Despite much progress, many questions regarding fault and anthropogenic processes in the region still remain. In this study, we combine satellite InSAR and NASA airborne UAVSAR data to image fault and anthropogenic deformation. The UAVSAR data cover fault perpendicular swaths imaged from opposing look directions and fault parallel swaths since 2009. The much finer spatial resolution and optimized viewing geometry provide important constraints on near fault deformation and fault slip at very shallow depth. We performed a synoptic InSAR time series analysis using Sentinel-1, ALOS, and UAVSAR interferograms. We estimate azimuth mis-registration between single look complex (SLC) images of Sentinel-1 in a stack sense to achieve accurate azimuth co-registration between SLC images for low coherence and/or long interval interferometric pairs. We show that it is important to correct large-scale ionosphere features in ALOS-2 ScanSAR data for accurate deformation measurements. Joint analysis of UAVSAR and ALOS interferometry measurements show clear variability in deformation along the fault strike, suggesting variable fault creep and locking at depth and along strike. In addition to fault creep, the L-band ALOS, and especially ALOS-2 ScanSAR interferometry, show large-scale ground

Interferometric Imaging and its Application to 4D Imaging

KAUST Repository

Sinha, Mrinal

2018-03-01

This thesis describes new interferometric imaging methods for migration and waveform inversion. The key idea is to use reflection events from a known reference reflector to ”naturally redatum” the receivers and sources to the reference reflector. Here, ”natural redatuming” is a data-driven process where the redatuming Green’s functions are obtained from the data. Interferometric imaging eliminates the statics associated with the noisy overburden above the reference reflector. To mitigate the defocussing caused by overburden errors I first propose the use of interferometric least-squares migration (ILSM) to estimate the migration image. Here, a known reflector is used as the reference interface for ILSM, and the data are naturally redatumed to this reference interface before imaging. Numerical results on synthetic and field data show that ILSM can significantly reduce the defocussing artifacts in the migration image. Next, I develop a waveform tomography approach for inverting the velocity model by mitigating the velocity errors in the overburden. Unresolved velocity errors in the overburden velocity model can cause conventional full-waveform inversion to get stuck in a local minimum. To resolve this problem, I present interferometric full-waveform inversion (IFWI), where conventional waveform tomography is reformulated so a velocity model is found that minimizes the objective function with an interferometric crosscorrelogram misfit. Numerical examples show that IFWI, compared to FWI, computes a significantly more accurate velocity model in the presence of a nearsurface with unknown velocity anomalies. I use IFWI and ILSM for 4D imaging where seismic data are recorded at different times over the same reservoir. To eliminate the time-varying effects of the near surface both data sets are virtually redatumed to a common reference interface before migration. This largely eliminates the overburden-induced statics errors in both data sets. Results with

Advanced radar-interpretation of InSAR time series for mapping and characterization of geological processes

OpenAIRE

Cigna, F.; Del Ventisette, C.; Liguori, V.; Casagli, N.

2011-01-01

We present a new post-processing methodology for the analysis of InSAR (Synthetic Aperture Radar Interferometry) multi-temporal measures, based on the temporal under-sampling of displacement time series, the identification of potential changes occurring during the monitoring period and, eventually, the classification of different deformation behaviours. The potentials of this approach for the analysis of geological processes were tested on the case study of Naro (Italy), specifically selected...

Integrating interferometric SAR data with levelling measurements of land subsidence using geostatistics

NARCIS (Netherlands)

Zhou, Y.; Stein, A.; Molenaar, M.

2003-01-01

Differential Synthetic Aperture Radar (SAR) interferometric (D-InSAR) data of ground surface deformation are affected by several error sources associated with image acquisitions and data processing. In this paper, we study the use of D-InSAR for quantifying land subsidence due to groundwater

Segmentation of high-resolution InSar data of tropical forest using Fourier parameterised deformable models

NARCIS (Netherlands)

Varekamp, C.; Hoekman, D.H.

2001-01-01

Currently, tree maps are produced from field measurements that are time consuming and expensive. Application of existing techniques based on aerial photography is often hindered by cloud cover. This has initiated research into the segmentation of high resolution airborne interferometric Synthetic

InSAR atmospheric correction using Himawari-8 Geostationary Meteorological Satellite

Science.gov (United States)

Kinoshita, Y.; Nimura, T.; Furuta, R.

2017-12-01

The atmospheric delay effect is one of the limitations for the accurate surface displacement detection by Synthetic Aperture Radar Interferometry (InSAR). Many previous studies have attempted to mitigate the neutral atmospheric delay in InSAR (e.g. Jolivet et al. 2014; Foster et al. 2006; Kinoshita et al. 2013). Hanssen et al. (2001) investigated the relationship between the 27 hourly observations of GNSS precipitable water vapor (PWV) and the infrared brightness temperature derived from visible satellite imagery, and showed a good correlation. Here we showed a preliminary result of the newly developed method for the neutral atmospheric delay correction using the Himawari-8 Japanese geostationary meteorological satellite data. The Himawari-8 satellite is the Japanese state-of-the-art geostationary meteorological satellite that has 16 observation channels and has spatial resolutions of 0.5 km (visible) and 2.0 km (near-infrared and infrared) with an time interval of 2.5 minutes around Japan. To estimate the relationship between the satellite brightness temperature and the atmospheric delay amount. Since the InSAR atmospheric delay is principally the same as that in GNSS, we at first compared the Himawari-8 data with the GNSS zenith tropospheric delay data derived from the Japanese dense GNSS network. The comparison of them showed that the band with the wavelength of 6.9 μm had the highest correlation to the GNSS observation. Based on this result, we developed an InSAR atmospheric delay model that uses the Himawari-8 6.9 μm band data. For the model validation, we generated InSAR images from the ESA's C-band Sentinel-1 SLC data with the GAMMA SAR software. We selected two regions around Tokyo and Sapporo (both in Japan) as the test sites because of the less temporal decorrelation. The validation result showed that the delay model reasonably estimate large scale phase variation whose spatial scale was on the order of over 20 km. On the other hand, phase variations of

Comparison of interferometric and stereo-radargrammetric 3D metrics in mapping of forest resources

Science.gov (United States)

Karila, K.; Karjalainen, M.; Yu, X.; Vastaranta, M.; Holopainen, M.; Hyyppa, J.

2015-04-01

Accurate forest resources maps are needed in diverse applications ranging from the local forest management to the global climate change research. In particular, it is important to have tools to map changes in forest resources, which helps us to understand the significance of the forest biomass changes in the global carbon cycle. In the task of mapping changes in forest resources for wide areas, Earth Observing satellites could play the key role. In 2013, an EU/FP7-Space funded project "Advanced_SAR" was started with the main objective to develop novel forest resources mapping methods based on the fusion of satellite based 3D measurements and in-situ field measurements of forests. During the summer 2014, an extensive field surveying campaign was carried out in the Evo test site, Southern Finland. Forest inventory attributes of mean tree height, basal area, mean stem diameter, stem volume, and biomass, were determined for 91 test plots having the size of 32 by 32 meters (1024 m2). Simultaneously, a comprehensive set of satellite and airborne data was collected. Satellite data also included a set of TanDEM-X (TDX) and TerraSAR-X (TSX) X-band synthetic aperture radar (SAR) images, suitable for interferometric and stereo-radargrammetric processing to extract 3D elevation data representing the forest canopy. In the present study, we compared the accuracy of TDX InSAR and TSX stereo-radargrammetric derived 3D metrics in forest inventory attribute prediction. First, 3D data were extracted from TDX and TSX images. Then, 3D data were processed as elevations above the ground surface (forest canopy height values) using an accurate Digital Terrain Model (DTM) based on airborne laser scanning survey. Finally, 3D metrics were calculated from the canopy height values for each test plot and the 3D metrics were compared with the field reference data. The Random Forest method was used in the forest inventory attributes prediction. Based on the results InSAR showed slightly better

Detecting Faults in Southern California using Computer-Vision Techniques and Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) Interferometry

Science.gov (United States)

Barba, M.; Rains, C.; von Dassow, W.; Parker, J. W.; Glasscoe, M. T.

2013-12-01

Knowing the location and behavior of active faults is essential for earthquake hazard assessment and disaster response. In Interferometric Synthetic Aperture Radar (InSAR) images, faults are revealed as linear discontinuities. Currently, interferograms are manually inspected to locate faults. During the summer of 2013, the NASA-JPL DEVELOP California Disasters team contributed to the development of a method to expedite fault detection in California using remote-sensing technology. The team utilized InSAR images created from polarimetric L-band data from NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) project. A computer-vision technique known as 'edge-detection' was used to automate the fault-identification process. We tested and refined an edge-detection algorithm under development through NASA's Earthquake Data Enhanced Cyber-Infrastructure for Disaster Evaluation and Response (E-DECIDER) project. To optimize the algorithm we used both UAVSAR interferograms and synthetic interferograms generated through Disloc, a web-based modeling program available through NASA's QuakeSim project. The edge-detection algorithm detected seismic, aseismic, and co-seismic slip along faults that were identified and compared with databases of known fault systems. Our optimization process was the first step toward integration of the edge-detection code into E-DECIDER to provide decision support for earthquake preparation and disaster management. E-DECIDER partners that will use the edge-detection code include the California Earthquake Clearinghouse and the US Department of Homeland Security through delivery of products using the Unified Incident Command and Decision Support (UICDS) service. Through these partnerships, researchers, earthquake disaster response teams, and policy-makers will be able to use this new methodology to examine the details of ground and fault motions for moderate to large earthquakes. Following an earthquake, the newly discovered faults can

An Improved InSAR Image Co-Registration Method for Pairs with Relatively Big Distortions or Large Incoherent Areas

Directory of Open Access Journals (Sweden)

Zhenwei Chen

2016-09-01

Full Text Available Co-registration is one of the most important steps in interferometric synthetic aperture radar (InSAR data processing. The standard offset-measurement method based on cross-correlating uniformly distributed patches takes no account of specific geometric transformation between images or characteristics of ground scatterers. Hence, it is inefficient and difficult to obtain satisfying co-registration results for image pairs with relatively big distortion or large incoherent areas. Given this, an improved co-registration strategy is proposed in this paper which takes both the geometric features and image content into consideration. Firstly, some geometric transformations including scale, flip, rotation, and shear between images were eliminated based on the geometrical information, and the initial co-registration polynomial was obtained. Then the registration points were automatically detected by integrating the signal-to-clutter-ratio (SCR thresholds and the amplitude information, and a further co-registration process was performed to refine the polynomial. Several comparison experiments were carried out using 2 TerraSAR-X data from the Hong Kong airport and 21 PALSAR data from the Donghai Bridge. Experiment results demonstrate that the proposed method brings accuracy and efficiency improvements for co-registration and processing abilities in the cases of big distortion between images or large incoherent areas in the images. For most co-registrations, the proposed method can enhance the reliability and applicability of co-registration and thus promote the automation to a higher level.

An Improved InSAR Image Co-Registration Method for Pairs with Relatively Big Distortions or Large Incoherent Areas.

Science.gov (United States)

Chen, Zhenwei; Zhang, Lei; Zhang, Guo

2016-09-17

Co-registration is one of the most important steps in interferometric synthetic aperture radar (InSAR) data processing. The standard offset-measurement method based on cross-correlating uniformly distributed patches takes no account of specific geometric transformation between images or characteristics of ground scatterers. Hence, it is inefficient and difficult to obtain satisfying co-registration results for image pairs with relatively big distortion or large incoherent areas. Given this, an improved co-registration strategy is proposed in this paper which takes both the geometric features and image content into consideration. Firstly, some geometric transformations including scale, flip, rotation, and shear between images were eliminated based on the geometrical information, and the initial co-registration polynomial was obtained. Then the registration points were automatically detected by integrating the signal-to-clutter-ratio (SCR) thresholds and the amplitude information, and a further co-registration process was performed to refine the polynomial. Several comparison experiments were carried out using 2 TerraSAR-X data from the Hong Kong airport and 21 PALSAR data from the Donghai Bridge. Experiment results demonstrate that the proposed method brings accuracy and efficiency improvements for co-registration and processing abilities in the cases of big distortion between images or large incoherent areas in the images. For most co-registrations, the proposed method can enhance the reliability and applicability of co-registration and thus promote the automation to a higher level.

InSAR observation of seasonal ground surface deformation in permafrost area near Batagay, Siberia

Science.gov (United States)

Yanagiya, K.; Furuya, M.

2017-12-01

Thawing of permafrost can lead to ground deformation. Ground deformation has been studied as a serious problem in the Arctic Ocean coastal area such as Russia for a long time, because the deformation causes damage to architectures at these areas. However, there have been no quantitative observation data, and the spatial and temporal distributions have hardly been investigated. On the other hand, by the recently global warming influence, the importance of organic carbon stored in permafrost is pointed out. Although the release of methane gas is confirmed in some thermokarst lakes, it is very difficult to observe the permafrost in a wide area by field study. Instead, it is technically possible to monitor the subsidence and uplift of the ground over the permafrost area, which could potentially make a significant contribution to the monitoring thawing process of permafrost. In this study, we attempted to detect ground deformation signal in permafrost area by remote sensing using interferometric synthetic aperture radar (InSAR). Using the data of two SAR satellites ALOS and ALOS2 launched by JAXA, we observed recent ground deformation from 2007 to 2016. Particularly recent observations of ALOS2 from 2014 to 2016 discovered distant displacements towards the LOS direction in the northeast region from the town of Batagay,Siberia. The diameter of the displacements area covers about 7.7 km. In this study, we considered that this signal is likely to be due to permafrost thawing, we also investigated the seasonal characteristics and looked back ALOS data of this area. In addition, since the high latitude area, observation results include noise due to the ionosphere, so we tried to remove the noise.

SAR Interferogram Filtering of Shearlet Domain Based on Interferometric Phase Statistics

Directory of Open Access Journals (Sweden)

Yonghong He

2017-02-01

Full Text Available This paper presents a new filtering approach for Synthetic Aperture Radar (SAR interferometric phase noise reduction in the shearlet domain, depending on the coherent statistical characteristics. Shearlets provide a multidirectional and multiscale decomposition that have advantages over wavelet filtering methods when dealing with noisy phase fringes. Phase noise in SAR interferograms is directly related to the interferometric coherence and the look number of the interferogram. Therefore, an optimal interferogram filter should incorporate information from both of them. The proposed method combines the phase noise standard deviation with the shearlet transform. Experimental results show that the proposed method can reduce the interferogram noise while maintaining the spatial resolution, especially in areas with low coherence.

Mitigation Atmospheric Effects in Interferogram with Using Integrated Meris/modis Data and a Case Study Over Southern California

Science.gov (United States)

Wang, X.; Zhang, P.; Sun, Z.

2018-04-01

Interferometric synthetic aperture radar(InSAR), as a space geodetictechnology, had been testified a high potential means of earth observation providing a method fordigital elevation model (DEM) and surface deformation monitoring of high precision. However, the accuracy of the interferometric synthetic aperture radar is mainly limited by the effects of atmospheric water vapor. In order to effectively measure topography or surface deformations by synthetic aperture radar interferometry (InSAR), it is necessary to mitigate the effects of atmospheric water vapor on the interferometric signals. This paper analyzed the atmospheric effects on the interferogram quantitatively, and described a result of estimating Precipitable Water Vapor (PWV) from the the Medium Resolution Imaging Spectrometer (MERIS), Moderate Resolution Imaging Spectroradiometer (MODIS) and the ground-based GPS, compared the MERIS/MODIS PWV with the GPS PWV. Finally, a case study for mitigating atmospheric effects in interferogramusing with using the integration of MERIS and MODIS PWV overSouthern California is given. The result showed that such integration approach benefits removing or reducing the atmospheric phase contribution from the corresponding interferogram, the integrated Zenith Path Delay Difference Maps (ZPDDM) of MERIS and MODIS helps reduce the water vapor effects efficiently, the standard deviation (STD) of interferogram is improved by 23 % after the water vapor correction than the original interferogram.

Temporal Decorrelation Effect in Carbon Stocks Estimation Using Polarimetric Interferometry Synthetic Aperture Radar (PolInSAR (Case Study: Southeast Sulawesi Tropical Forest

Directory of Open Access Journals (Sweden)

Laode M Golok Jaya

2017-07-01

Full Text Available This paper was aimed to analyse the effect of temporal decorrelation in carbon stocks estimation. Estimation of carbon stocks plays important roles particularly to understand the global carbon cycle in the atmosphere regarding with climate change mitigation effort. PolInSAR technique combines the advantages of Polarimetric Synthetic Aperture Radar (PolSAR and Interferometry Synthetic Aperture Radar (InSAR technique, which is evidenced to have significant contribution in radar mapping technology in the last few years. In carbon stocks estimation, PolInSAR provides information about vertical vegetation structure to estimate carbon stocks in the forest layers. Two coherence Synthetic Aperture Radar (SAR images of ALOS PALSAR full-polarimetric with 46 days temporal baseline were used in this research. The study was carried out in Southeast Sulawesi tropical forest. The research method was by comparing three interferometric phase coherence images affected by temporal decorrelation and their impacts on Random Volume over Ground (RvoG model. This research showed that 46 days temporal baseline has a significant impact to estimate tree heights of the forest cover where the accuracy decrease from R2=0.7525 (standard deviation of tree heights is 2.75 meters to R2=0.4435 (standard deviation 4.68 meters and R2=0.3772 (standard deviation 3.15 meters respectively. However, coherence optimisation can provide the best coherence image to produce a good accuracy of carbon stocks.

Magnitude and extent of land subsidence in central Mexico revealed by regional InSAR ALOS time-series survey

Science.gov (United States)

Chaussard, E.; Wdowinski, S.; Amelung, F.; Cabral-Cano, E.

2013-05-01

Massive groundwater extraction is very common in Mexico and is well known to result in land subsidence. However, most surveys dedicated to land subsidence focus on one single city, mainly Mexico City, and thus fail to provide a comprehensive picture of the problem. Here we use a space-based radar remote sensing technique, known as Interferometric Synthetic Aperture Radar (InSAR) to detect land subsidence in the entire central Mexico area. We used data from the Japanese satellite ALOS, processed over 600 SAR images acquired between 2007-2011 and produced over 3000 interferograms to cover and area of 200,000 km2 in central Mexico. We identify land subsidence in twenty-one areas, including seventeen cities, namely from east to west, Puebla, Mexico city, Toluca de Lerdo, Queretaro, San Luis de la Paz, south of San Luis de la Paz, Celaya, south of Villa de Reyes, San Luis Potosi, west of Villa de Arista, Morelia, Salamanca, Irapuato, Silao, Leon, Aguascalientes, north of Aguascalientes, Zamora de Hidalgo, Guadalajara, Ahuacatlan, and Tepic. Subsidence rates of 30 cm/yr are observed in Mexico City, while in the other locations typical rates of 5-10 cm/yr are noticed. Regional surveys of this type are necessary for the development of hazard mitigation plans and efficient use of ground-based monitoring. We additionally correlate subsidence with land use, surface geology, and faults distribution and suggest that groundwater extraction for agricultural, urban, and industrial uses are the main causes of land subsidence. We also reveal that the limits of the subsiding areas often correlate with existing faults, motion on these faults being driven by water extraction rather than by tectonic activity. In all the subsiding locations we observe high ground velocity gradients emphasizing the significant risks associated with land subsidence in central Mexico. Averaged 2007-2011 ground velocity map from ALOS InSAR time-series in central Mexico, revealing land subsidence in 21

Land subsidence, Ground Fissures and Buried Faults: InSAR Monitoring of Ciudad Guzmán (Jalisco, Mexico

Directory of Open Access Journals (Sweden)

Carlo Alberto Brunori

2015-07-01

Full Text Available We study land subsidence processes and the associated ground fissuring, affecting an active graben filled by thick unconsolidated deposits by means of InSAR techniques and fieldwork. On 21 September 2012, Ciudad Guzmán (Jalisco, Mexico was struck by ground fissures of about 1.5 km of length, causing the deformation of the roads and the propagation of fissures in adjacent buildings. The field survey showed that fissures alignment is coincident with the escarpments produced on 19 September 1985, when a strong earthquake with magnitude 8.1 struck central Mexico. In order to detect and map the spatio-temporal features of the processes that led to the 2012 ground fissures, we applied InSAR multi-temporal techniques to process ENVISAT-ASAR and RADARSAT-2 satellite SAR images acquired between 2003 and 2012. We detect up to 20 mm/year of subsidence of the northwestern part of Ciudad Guzmán. These incremental movements are consistent with the ground fissures observed in 2012. Based on interferometric results, field data and 2D numerical model, we suggest that ground deformations and fissuring are due to the presence of areal subsidence correlated with variable sediment thickness and differential compaction, partly driven by the exploitation of the aquifers and controlled by the distribution and position of buried faults.

Imaging the complex geometry of a magma reservoir using FEM-based linear inverse modeling of InSAR data: application to Rabaul Caldera, Papua New Guinea

Science.gov (United States)

Ronchin, Erika; Masterlark, Timothy; Dawson, John; Saunders, Steve; Martì Molist, Joan

2017-06-01

We test an innovative inversion scheme using Green's functions from an array of pressure sources embedded in finite-element method (FEM) models to image, without assuming an a-priori geometry, the composite and complex shape of a volcano deformation source. We invert interferometric synthetic aperture radar (InSAR) data to estimate the pressurization and shape of the magma reservoir of Rabaul caldera, Papua New Guinea. The results image the extended shallow magmatic system responsible for a broad and long-term subsidence of the caldera between 2007 February and 2010 December. Elastic FEM solutions are integrated into the regularized linear inversion of InSAR data of volcano surface displacements in order to obtain a 3-D image of the source of deformation. The Green's function matrix is constructed from a library of forward line-of-sight displacement solutions for a grid of cubic elementary deformation sources. Each source is sequentially generated by removing the corresponding cubic elements from a common meshed domain and simulating the injection of a fluid mass flux into the cavity, which results in a pressurization and volumetric change of the fluid-filled cavity. The use of a single mesh for the generation of all FEM models avoids the computationally expensive process of non-linear inversion and remeshing a variable geometry domain. Without assuming an a-priori source geometry other than the configuration of the 3-D grid that generates the library of Green's functions, the geodetic data dictate the geometry of the magma reservoir as a 3-D distribution of pressure (or flux of magma) within the source array. The inversion of InSAR data of Rabaul caldera shows a distribution of interconnected sources forming an amorphous, shallow magmatic system elongated under two opposite sides of the caldera. The marginal areas at the sides of the imaged magmatic system are the possible feeding reservoirs of the ongoing Tavurvur volcano eruption of andesitic products on the

L band InSAR sudy on the Ganos section of the North Anatolian Fault Zone (NAFZ)

Science.gov (United States)

de Michele, Marcello

2016-04-01

The North Anatolian Fault (NAF), with a total length of about 1500 km, is one of the most active right-lateral strike-slip faults in the world. It defines the tectonic boundary between the Anatolian Plate and the Eurasian Plate in northern Turkey, accommodating ~14-30 mm/yr of relative plate motion between the two plates (fig. 1). The Gazikoy-Saros segment (the Ganos fault, GF) is the onshore segment of the northern strand of the NAF between the Marmara Sea and the Gulf of Saros. It was last ruptured in 1912 with a Ms=7.4 earthquake that broke the entire inland segment of the fault, a length of about 50 km, and produced a right-lateral strike-slip component of at least 3 m. Other large historical earthquakes that have been attributed to the Ganos fault occurred in A.D. 824, 1343, 1509 and 1766 (e. g. Reilinger et al., 2000; Meade et al., 2002; Motagh et al., 2007; Janssen et al., 2009; Megraoui et al., 2012 ; Ersen Aksoy et al., 2010). The GF forms a 45 km long linear fault system and represents the link between the northern strand of the NAFZ in the Sea of Marmara and the North Aegean Trough where slip partitioning results in branching of the fault zone. The present study aims at showing the results retrieved from L band Interferometric Syntethic Aperture Radar (InSAR) measurements for the monitoring of Crustal Deformation in the Anatolian Fault Zone in the frame of the MARMARA SUPERSITE PROJECT "MARSITE" on the Ganos section of the North Anatolian fault zone. We processed SAR data made available through the CAT-1 ESA (European Space Agency) archives, acquired by the L-band radar sensor ALOS PALSAR between 2007 and 2011. The aim of this exercise is to test L-band capabilities to map the spatial and temporal evolution of the present-day crustal deformation phenomena affecting the Ganos section of the NAFZ with high level of spatial details. The goal of this task is to assess whether InSAR L-Band data can be useful to evaluate the long-term behavior of active faults

InSAR deformation monitoring of high risk landslides

Science.gov (United States)

Singhroy, V.; Li, J.

2013-05-01

During the past year there were at least twenty five media reports of landslides and seismic activities some fatal, occurring in various areas in Canada. These high risk geohazards sites requires high resolution monitoring both spatially and temporally for mitigation purposes, since they are near populated areas and energy, transportation and communication corridors. High resolution air photos, lidar and satellite images are quite common in areas where the landslides can be fatal. Radar interferometry (InSAR) techniques using images from several radar satellites are increasingly being used in slope stability assessment. This presentation provides examples of using high-resolution (1-3m) frequent revisits InSAR techniques from RADARSAT 2 and TerraSAR X to monitor several types of high-risk landslides affecting transportation and energy corridors and populated areas. We have analyses over 200 high resolution InSAR images over a three year period on geologically different landslides. The high-resolution InSAR images are effective in characterizing differential motion within these low velocity landslides. The low velocity landslides become high risk during the active wet spring periods. The wet soils are poor coherent targets and corner reflectors provide an effective means of InSAR monitoring the slope activities.

Cross-calibration of interferometric SAR data

DEFF Research Database (Denmark)

Dall, Jørgen

2003-01-01

Generation of digital elevation models from interferometric synthetic aperture radar (SAR) data is a well established technique. Achieving a high geometric fidelity calls for a calibration accounting for inaccurate navigation data and system parameters as well as system imperfections. Fully...... automated calibration techniques are preferable, especially for operational mapping. The author presents one such technique, called cross-calibration. Though developed for single-pass interferometry, it may be applicable to multi-pass interferometry, too. Cross-calibration requires stability during mapping...... ground control point is often needed. The paper presents the principles and mathematics of the cross-calibration technique and illustrates its successful application to EMISAR data....

Performance Analysis of Measurement Inaccuracies of IMU/GPS on Airborne Repeat-pass Interferometric SAR in the Presence of Squint

Directory of Open Access Journals (Sweden)

Deng Yuan

2014-08-01

Full Text Available In the MOtion COmpensation (MOCO approach to airborne repeat-pass interferometric Synthetic Aperture Radar (SAR based on motion measurement data, the measurement inaccuracies of Inertial Measurement Unit/Global Positioning System (IMU/GPS and the positioning errors of the target, which may contribute to the residual uncompensated motion errors, affect the imaging result and interferometric measurement. Considering the effects of the two types of error, this paper builds a mathematical model of residual motion errors in presence of squint, and analyzes the effects on the residual motion errors induced by the measurement inaccuracies of IMU/GPS and the positioning errors of the target. In particular, the effects of various measurement inaccuracies of IMU/GPS on interferometric SAR image quality, interferometric phase, and digital elevation model precision are disscussed. Moreover, the paper quantitatively researches the effects of residual motion errors on airborne repeat-pass interferometric SAR through theoretical and simulated analyses and provides theoretical bases for system design and signal processing.

Volcano deformation source parameters estimated from InSAR: Sensitivities to uncertainties in seismic tomography

Science.gov (United States)

Masterlark, Timothy; Donovan, Theodore; Feigl, Kurt L.; Haney, Matt; Thurber, Clifford H.; Tung, Sui

2016-01-01

The eruption cycle of a volcano is controlled in part by the upward migration of magma. The characteristics of the magma flux produce a deformation signature at the Earth's surface. Inverse analyses use geodetic data to estimate strategic controlling parameters that describe the position and pressurization of a magma chamber at depth. The specific distribution of material properties controls how observed surface deformation translates to source parameter estimates. Seismic tomography models describe the spatial distributions of material properties that are necessary for accurate models of volcano deformation. This study investigates how uncertainties in seismic tomography models propagate into variations in the estimates of volcano deformation source parameters inverted from geodetic data. We conduct finite element model-based nonlinear inverse analyses of interferometric synthetic aperture radar (InSAR) data for Okmok volcano, Alaska, as an example. We then analyze the estimated parameters and their uncertainties to characterize the magma chamber. Analyses are performed separately for models simulating a pressurized chamber embedded in a homogeneous domain as well as for a domain having a heterogeneous distribution of material properties according to seismic tomography. The estimated depth of the source is sensitive to the distribution of material properties. The estimated depths for the homogeneous and heterogeneous domains are 2666 ± 42 and 3527 ± 56 m below mean sea level, respectively (99% confidence). A Monte Carlo analysis indicates that uncertainties of the seismic tomography cannot account for this discrepancy at the 99% confidence level. Accounting for the spatial distribution of elastic properties according to seismic tomography significantly improves the fit of the deformation model predictions and significantly influences estimates for parameters that describe the location of a pressurized magma chamber.

Gravity and InSAR remote sensing of groundwater usage in the Sahel and Horn of Africa

Science.gov (United States)

Neely, W.; Borsa, A. A.; Burney, J. A.; Devlin, K.

2016-12-01

Changes in the Earth's climatic systems influence agro-ecological conditions on local, regional, and global scales. With the world's highest population growth rate, sub-Saharan Africa faces particularly acute concerns regarding food security and resource management. Historical sources of surface water for agricultural production may become less reliable and/or limited with increased climate variability, and African countries have already begun to depend on more stable sources of groundwater. Expected increases in groundwater usage pose questions about the sustainability of current agricultural practices, which require new sources of information to answer. Due to the logistics and costs to implement in situ networks to monitor regional water security, current remote sensing missions offer an affordable alternative. The Gravity Recovery and Climate Experiment (GRACE) has proven to be effective in quantifying changes in terrestrial water storage (TWS) at the regional scale using near-monthly gravity measurements from orbit. Using over a decade of measurements, we estimate TWS anomalies in Niger and Ethiopia. These anomalies offer a proxy for hydrological stressing, indicating potential targets for additional analysis. We use independent, but complementary, estimates of surface displacements from Interferometric Synthetic Aperture Radar (InSAR) to provide information on local groundwater withdrawal. Using data from ESA's Sentinel 1 mission and JAXA's Advanced Land Observing Satellite (ALOS) missions, we characterize the surface deformation over the past decade in regions of active groundwater pumping using the Small Baseline Subset (SBAS) technique. In particular, we investigate ties of ground motion to known agricultural/industrial land usage near Niamey, Niger and Eastern Oromia, Ethiopia to better understand how human activity affects available groundwater resources.

InSAR Deformation Time Series Processed On-Demand in the Cloud

Science.gov (United States)

Horn, W. B.; Weeden, R.; Dimarchi, H.; Arko, S. A.; Hogenson, K.

2017-12-01

During this past year, ASF has developed a cloud-based on-demand processing system known as HyP3 (http://hyp3.asf.alaska.edu/), the Hybrid Pluggable Processing Pipeline, for Synthetic Aperture Radar (SAR) data. The system makes it easy for a user who doesn't have the time or inclination to install and use complex SAR processing software to leverage SAR data in their research or operations. One such processing algorithm is generation of a deformation time series product, which is a series of images representing ground displacements over time, which can be computed using a time series of interferometric SAR (InSAR) products. The set of software tools necessary to generate this useful product are difficult to install, configure, and use. Moreover, for a long time series with many images, the processing of just the interferograms can take days. Principally built by three undergraduate students at the ASF DAAC, the deformation time series processing relies the new Amazon Batch service, which enables processing of jobs with complex interconnected dependencies in a straightforward and efficient manner. In the case of generating a deformation time series product from a stack of single-look complex SAR images, the system uses Batch to serialize the up-front processing, interferogram generation, optional tropospheric correction, and deformation time series generation. The most time consuming portion is the interferogram generation, because even for a fairly small stack of images many interferograms need to be processed. By using AWS Batch, the interferograms are all generated in parallel; the entire process completes in hours rather than days. Additionally, the individual interferograms are saved in Amazon's cloud storage, so that when new data is acquired in the stack, an updated time series product can be generated with minimal addiitonal processing. This presentation will focus on the development techniques and enabling technologies that were used in developing the time

Mapping ground surface deformation using temporarily coherent point SAR interferometry: Application to Los Angeles Basin

Science.gov (United States)

Zhang, L.; Lu, Zhong; Ding, X.; Jung, H.-S.; Feng, G.; Lee, C.-W.

2012-01-01

Multi-temporal interferometric synthetic aperture radar (InSAR) is an effective tool to detect long-term seismotectonic motions by reducing the atmospheric artifacts, thereby providing more precise deformation signal. The commonly used approaches such as persistent scatterer InSAR (PSInSAR) and small baseline subset (SBAS) algorithms need to resolve the phase ambiguities in interferogram stacks either by searching a predefined solution space or by sparse phase unwrapping methods; however the efficiency and the success of phase unwrapping cannot be guaranteed. We present here an alternative approach – temporarily coherent point (TCP) InSAR (TCPInSAR) – to estimate the long term deformation rate without the need of phase unwrapping. The proposed approach has a series of innovations including TCP identification, TCP network and TCP least squares estimator. We apply the proposed method to the Los Angeles Basin in southern California where structurally active faults are believed capable of generating damaging earthquakes. The analysis is based on 55 interferograms from 32 ERS-1/2 images acquired during Oct. 1995 and Dec. 2000. To evaluate the performance of TCPInSAR on a small set of observations, a test with half of interferometric pairs is also performed. The retrieved TCPInSAR measurements have been validated by a comparison with GPS observations from Southern California Integrated GPS Network. Our result presents a similar deformation pattern as shown in past InSAR studies but with a smaller average standard deviation (4.6 mm) compared with GPS observations, indicating that TCPInSAR is a promising alternative for efficiently mapping ground deformation even from a relatively smaller set of interferograms.

Shallow deformation of the San Andreas fault 5 years following the 2004 Parkfield earthquake (Mw6) combining ERS2 and Envisat InSAR.

Science.gov (United States)

Bacques, Guillaume; de Michele, Marcello; Raucoules, Daniel; Aochi, Hideo; Rolandone, Frédérique

2018-04-16

This study focuses on the shallow deformation that occurred during the 5 years following the Parkfield earthquake (28/09/2004, Mw 6, San Andreas Fault, California). We use Synthetic Aperture Radar interferometry (InSAR) to provide precise measurements of transient deformations after the Parkfield earthquake between 2005 and 2010. We propose a method to combine both ERS2 and ENVISAT interferograms to increase the temporal data sampling. Firstly, we combine 5 years of available Synthetic Aperture Radar (SAR) acquisitions including both ERS-2 and Envisat. Secondly, we stack selected interferograms (both from ERS2 and Envisat) for measuring the temporal evolution of the ground velocities at given time intervals. Thanks to its high spatial resolution, InSAR could provide new insights on the surface fault motion behavior over the 5 years following the Parkfield earthquake. As a complement to previous studies in this area, our results suggest that shallow transient deformations affected the Creeping-Parkfield-Cholame sections of the San Andreas Fault after the 2004 Mw6 Parkfield earthquake.

Seismic time-lapse imaging using Interferometric least-squares migration

KAUST Repository

Sinha, Mrinal

2016-09-06

One of the problems with 4D surveys is that the environmental conditions change over time so that the experiment is insufficiently repeatable. To mitigate this problem, we propose the use of interferometric least-squares migration (ILSM) to estimate the migration image for the baseline and monitor surveys. Here, a known reflector is used as the reference reflector for ILSM. Results with synthetic and field data show that ILSM can eliminate artifacts caused by non-repeatability in time-lapse surveys.

Seismic time-lapse imaging using Interferometric least-squares migration

KAUST Repository

Sinha, Mrinal; Schuster, Gerard T.

2016-01-01

One of the problems with 4D surveys is that the environmental conditions change over time so that the experiment is insufficiently repeatable. To mitigate this problem, we propose the use of interferometric least-squares migration (ILSM) to estimate the migration image for the baseline and monitor surveys. Here, a known reflector is used as the reference reflector for ILSM. Results with synthetic and field data show that ILSM can eliminate artifacts caused by non-repeatability in time-lapse surveys.

Radon-domain interferometric interpolation for reconstruction of the near-offset gap in marine seismic data

Science.gov (United States)

Xu, Zhuo; Sopher, Daniel; Juhlin, Christopher; Han, Liguo; Gong, Xiangbo

2018-04-01

In towed marine seismic data acquisition, a gap between the source and the nearest recording channel is typical. Therefore, extrapolation of the missing near-offset traces is often required to avoid unwanted effects in subsequent data processing steps. However, most existing interpolation methods perform poorly when extrapolating traces. Interferometric interpolation methods are one particular method that have been developed for filling in trace gaps in shot gathers. Interferometry-type interpolation methods differ from conventional interpolation methods as they utilize information from several adjacent shot records to fill in the missing traces. In this study, we aim to improve upon the results generated by conventional time-space domain interferometric interpolation by performing interferometric interpolation in the Radon domain, in order to overcome the effects of irregular data sampling and limited source-receiver aperture. We apply both time-space and Radon-domain interferometric interpolation methods to the Sigsbee2B synthetic dataset and a real towed marine dataset from the Baltic Sea with the primary aim to improve the image of the seabed through extrapolation into the near-offset gap. Radon-domain interferometric interpolation performs better at interpolating the missing near-offset traces than conventional interferometric interpolation when applied to data with irregular geometry and limited source-receiver aperture. We also compare the interferometric interpolated results with those obtained using solely Radon transform (RT) based interpolation and show that interferometry-type interpolation performs better than solely RT-based interpolation when extrapolating the missing near-offset traces. After data processing, we show that the image of the seabed is improved by performing interferometry-type interpolation, especially when Radon-domain interferometric interpolation is applied.

Surface deformation monitoring of Sinabung volcano using multi temporal InSAR method and GIS analysis for affected area assessment

Science.gov (United States)

Aditiya, A.; Aoki, Y.; Anugrah, R. D.

2018-04-01

Sinabung Volcano which located in northern part of Sumatera island is part of a hundred active volcano in Indonesia. Surface deformation is detected over Sinabung Volcano and surrounded area since the first eruption in 2010 after 400 years long rest. We present multi temporal Interferometric Synthetic Aperture Radar (InSAR) time-series method of ALOS-2 L-band SAR data acquired from December 2014 to July 2017 to reveal surface deformation with high spatial resolution. The method includes focusing the SAR data, generating interferogram and phase unwrapping using SNAPHU tools. The result reveal significant deformation over Sinabung Volcano areas at rates up to 10 cm during observation period and the highest deformation occurs in western part which is trajectory of lava. We concluded the observed deformation primarily caused by volcanic activity respectively after long period of rest. In addition, Geographic Information System (GIS) analysis produces disaster affected areas of Sinabung eruption. GIS is reliable technique to estimate the impact of the hazard scenario to the exposure data and develop scenarios of disaster impacts to inform their contingency and emergency plan. The GIS results include the estimated affected area divided into 3 zones based on pyroclastic lava flow and pyroclastic fall (incandescent rock and ash). The highest impact is occurred in zone II due to many settlements are scattered in this zone. This information will be support stakeholders to take emergency preparation for disaster reduction. The continuation of this high rate of decline tends to endanger the population in next periods.

COMPARAÇÃO ENTRE DADOS ALTIMÉTRICOS SHUTTLE RADAR TOPOGRAPHY MISSION , CARTAS TOPOGRÁFICAS E GPS: NUMA ÁREA COM RELEVO ESCARPADO

OpenAIRE

Eduardo da Silva Pinheiro

2006-01-01

Shuttle Radar Topography Mission (SRTM) flown with Space Shuttle Endeavour, which was launched on 11 February 2000 , aimed to obtain the Earth digital elevation data (DEM). These data were acquired using Interferometric Synthetic Aperture Radar (InSAR) in C (5.6cm – 5.3GHz) and X (3.1cm – 9.6GHz) bands. This paper presents a comparative analysis of elevation data from SRTM and Topographic map (1:50.000) with Differential - GPS field data. The study was conducted in Planalto das Araucárias ar...

Super-virtual interferometric diffractions as guide stars

KAUST Repository

Dai, Wei

2011-01-01

A significant problem in seismic imaging is seismically seeing below salt structures: large velocity contrasts and the irregular geometry of the salt-sediment interface strongly defocus both the downgoing and upgoing seismic wavefields. This can result in severely defocused migration images so as to seismically render some subsalt reserves invisible. The potential cure is a good estimate of the subsalt and salt velocity distributions, but that is also the problem: severe velocity contrasts prevent the appearance of coherent subsalt reflections in the surface records so that MVA or tomographic methods can become ineffective. We now present an interferometric method for extracting the diffraction signals that emanate from diffractors, also denoted as seismic guide stars. The signal-to-noise ratio of these interferometric diffractions is enhanced by N, where N is the number of source points coincident with the receiver points. Thus, diffractions from subsalt guide stars can then be rendered visible and so can be used for velocity analysis, migration, and focusing of subsalt reflections. Both synthetic and field data records are used to demonstrate the benefits and limitations of this method. © 2011 Society of Exploration Geophysicists.

Towards Slow-Moving Landslide Monitoring by Integrating Multi-Sensor InSAR Time Series Datasets: The Zhouqu Case Study, China

Directory of Open Access Journals (Sweden)

Qian Sun

2016-11-01

Full Text Available Although the past few decades have witnessed the great development of Synthetic Aperture Radar Interferometry (InSAR technology in the monitoring of landslides, such applications are limited by geometric distortions and ambiguity of 1D Line-Of-Sight (LOS measurements, both of which are the fundamental weakness of InSAR. Integration of multi-sensor InSAR datasets has recently shown its great potential in breaking through the two limits. In this study, 16 ascending images from the Advanced Land Observing Satellite (ALOS and 18 descending images from the Environmental Satellite (ENVISAT have been integrated to characterize and to detect the slow-moving landslides in Zhouqu, China between 2008 and 2010. Geometric distortions are first mapped by using the imaging geometric parameters of the used SAR data and public Digital Elevation Model (DEM data of Zhouqu, which allow the determination of the most appropriate data assembly for a particular slope. Subsequently, deformation rates along respective LOS directions of ALOS ascending and ENVISAT descending tracks are estimated by conducting InSAR time series analysis with a Temporarily Coherent Point (TCP-InSAR algorithm. As indicated by the geometric distortion results, 3D deformation rates of the Xieliupo slope at the east bank of the Pai-lung River are finally reconstructed by joint exploiting of the LOS deformation rates from cross-heading datasets based on the surface–parallel flow assumption. It is revealed that the synergistic results of ALOS and ENVISAT datasets provide a more comprehensive understanding and monitoring of the slow-moving landslides in Zhouqu.

Ground surface deformation patterns, magma supply, and magma storage at Okmok volcano, Alaska, from InSAR analysis: 2. Coeruptive deflation, July-August 2008

Science.gov (United States)

Lu, Zhong; Dzurisin, Daniel

2010-01-01

A hydrovolcanic eruption near Cone D on the floor of Okmok caldera, Alaska, began on 12 July 2008 and continued until late August 2008. The eruption was preceded by inflation of a magma reservoir located beneath the center of the caldera and ∼3 km below sea level (bsl), which began immediately after Okmok's previous eruption in 1997. In this paper we use data from several radar satellites and advanced interferometric synthetic aperture radar (InSAR) techniques to produce a suite of 2008 coeruption deformation maps. Most of the surface deformation that occurred during the eruption is explained by deflation of a Mogi-type source located beneath the center of the caldera and 2–3 km bsl, i.e., essentially the same source that inflated prior to the eruption. During the eruption the reservoir deflated at a rate that decreased exponentially with time with a 1/e time constant of ∼13 days. We envision a sponge-like network of interconnected fractures and melt bodies that in aggregate constitute a complex magma storage zone beneath Okmok caldera. The rate at which the reservoir deflates during an eruption may be controlled by the diminishing pressure difference between the reservoir and surface. A similar mechanism might explain the tendency for reservoir inflation to slow as an eruption approaches until the pressure difference between a deep magma production zone and the reservoir is great enough to drive an intrusion or eruption along the caldera ring-fracture system.

Latest Rate, Extent, and Temporal Evolution of Growth Faulting over Greater Houston Region Revealed by Multi- Band InSAR Time-Series Analysis

Science.gov (United States)

Qu, F.; Lu, Z.; Kim, J. W.

2017-12-01

Growth faults are common and continue to evolve throughout the unconsolidated sediments of Greater Houston (GH) region in Texas. Presence of faults can induce localized surface displacements, aggravate localized subsidence, and discontinue the integrity of ground water flow. Property damages due to fault creep have become more evident during the past few years over the GH area, portraying the necessity of further study of these faults. Interferometric synthetic aperture radar (InSAR) has been proven to be effective in mapping creep along and/or across faults. However, extracting a short wavelength, as well as small amplitude of the creep signal (about 10-20 mm/year) from long time span interferograms is extremely difficult, especially in agricultural or vegetated areas. This paper aims to map and monitor the latest rate, extent, and temporal evolution of faulting at a highest spatial density over GH region using an improved Multi-temporal InSAR (MTI) technique. The method, with maximized usable signal and correlation, has the ability to identify and monitor the active faults to provide an accurate and elaborate image of the faults. In this study, two neighboring ALOS tracks and Sentinel-1A datasets are used. Many zones of steep phase gradients and/or discontinuities have been recognized from the long term velocity maps by both ALOS (2007-2011) and Sentinei-1A (2015-2017) imagery. Not only those previously known faults position but also the new fault traces that have not been mapped by other techniques are imaged by our MTI technique. Fault damage and visible cracking of ground were evident at most locations through our field survey. The discovery of new fault activation, or faults moved from earlier locations is a part of the Big Barn Fault and Conroe fault system, trending from southwest to northeast between Hockley and Conroe. The location of area of subsidence over GH is also shrinking and migrating toward the northeast (Montgomery County) after 2000. The

InSAR velocity field across the North Anatolian Fault (eastern Turkey): Implications for the loading and release of interseismic strain accumulation

KAUST Repository

Cakir, Ziyadin; Ergintav, Semih; Akoğlu, Ahmet M.; Ç akmak, Rahşan; Tatar, Orhan; Meghraoui, Mustapha

2014-01-01

We use the Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) technique with the European Space Agency's Envisat and ERS SAR data acquired on three neighboring descending tracks (T350, T078, and T307) to map the interseismic

Rupture process of the 2016 Mw 7.8 Ecuador earthquake from joint inversion of InSAR data and teleseismic P waveforms

Science.gov (United States)

Yi, Lei; Xu, Caijun; Wen, Yangmao; Zhang, Xu; Jiang, Guoyan

2018-01-01

The 2016 Ecuador earthquake ruptured the Ecuador-Colombia subduction interface where several historic megathrust earthquakes had occurred. In order to determine a detailed rupture model, Interferometric Synthetic Aperture Radar (InSAR) images and teleseismic data sets were objectively weighted by using a modified Akaika's Bayesian Information Criterion (ABIC) method to jointly invert for the rupture process of the earthquake. In modeling the rupture process, a constrained waveform length method, unlike the traditional subjective selected waveform length method, was used since the lengths of inverted waveforms were strictly constrained by the rupture velocity and rise time (the slip duration time). The optimal rupture velocity and rise time of the earthquake were estimated from grid search, which were determined to be 2.0 km/s and 20 s, respectively. The inverted model shows that the event is dominated by thrust movement and the released moment is 5.75 × 1020 Nm (Mw 7.77). The slip distribution extends southward along the Ecuador coast line in an elongated stripe at a depth between 10 and 25 km. The slip model is composed of two asperities and slipped over 4 m. The source time function is approximate 80 s that separated into two segments corresponding to the two asperities. The small magnitude of the slip occurred in the updip section of the fault plane resulted in small tsunami waves that were verified by observations near the coast. We suggest a possible situation that the rupture zone of the 2016 earthquake is likely not overlapped with that of the 1942 earthquake.

Tracking Human-Induced Landscape Disturbance at the Nasca Lines UNESCO World Heritage Site in Peru with COSMO-SkyMed InSAR

Directory of Open Access Journals (Sweden)

Francesca Cigna

2018-04-01

Full Text Available The “Lines and Geoglyphs of Nasca and Palpa” in Peru are among the most well-known UNESCO World Heritage Sites globally, and an exemplar of site where heritage assets cannot be separated from their natural and anthropogenic environment. The site is exposed to interactions with natural processes, as well as human presence. In this work, 3-m resolution synthetic aperture radar (SAR StripMap HIMAGE HH-polarised scenes acquired by the X-band COSMO-SkyMed constellation are exploited to track two events of human-induced landscape disturbance that occurred in December 2014 and January 2018. Pre-, cross-, and post-event interferometric SAR (InSAR pairs characterised by small temporal and normal baselines allow the detection of temporal decorrelation associated with the two events, the extent and time reference of which match with online photographic and video evidence, published literature, web news, and press releases by the Ministry of Culture in Peru. Further elements enhancing the understanding of the 2018 event come from 10-m resolution Sentinel-2B satellite data that reveal the occurrence of apparent changes of surface reflectance due to uncovering of the light grey-yellow clay underneath the darker pebble constituting the fragile surface of the Pampa de Jumana. This scientific study confirms that SAR imagery archives, such as those being built by COSMO-SkyMed for Nasca, prove valuable for the retrospective analysis and digital recording of human-induced landscape disturbance events from space. These archives therefore act as essential sources of geospatial information on the conservation history of heritage sites and assets.

Calibration of the TUD Ku-band Synthetic Aperture Radiometer

DEFF Research Database (Denmark)

Laursen, Brian; Skou, Niels

1995-01-01

The TUD Synthetic Aperture Radiometer is a 2-channel demonstration model that can simulate a thinned aperture radiometer having an unfilled aperture consisting of several small antenna elements. Aperture synthesis obtained by interferometric measurements using the antenna elements in pairs, follo...

Forest height estimation from mountain forest areas using general model-based decomposition for polarimetric interferometric synthetic aperture radar images

Science.gov (United States)

Minh, Nghia Pham; Zou, Bin; Cai, Hongjun; Wang, Chengyi

2014-01-01

The estimation of forest parameters over mountain forest areas using polarimetric interferometric synthetic aperture radar (PolInSAR) images is one of the greatest interests in remote sensing applications. For mountain forest areas, scattering mechanisms are strongly affected by the ground topography variations. Most of the previous studies in modeling microwave backscattering signatures of forest area have been carried out over relatively flat areas. Therefore, a new algorithm for the forest height estimation from mountain forest areas using the general model-based decomposition (GMBD) for PolInSAR image is proposed. This algorithm enables the retrieval of not only the forest parameters, but also the magnitude associated with each mechanism. In addition, general double- and single-bounce scattering models are proposed to fit for the cross-polarization and off-diagonal term by separating their independent orientation angle, which remains unachieved in the previous model-based decompositions. The efficiency of the proposed approach is demonstrated with simulated data from PolSARProSim software and ALOS-PALSAR spaceborne PolInSAR datasets over the Kalimantan areas, Indonesia. Experimental results indicate that forest height could be effectively estimated by GMBD.

A time series deformation estimation in the NW Himalayas using SBAS InSAR technique

Science.gov (United States)

Kumar, V.; Venkataraman, G.

2012-12-01

A time series land deformation studies in north western Himalayan region has been presented in this study. Synthetic aperture radar (SAR) interferometry (InSAR) is an important tool for measuring the land displacement caused by different geological processes [1]. Frequent spatial and temporal decorrelation in the Himalayan region is a strong impediment in precise deformation estimation using conventional interferometric SAR approach. In such cases, advanced DInSAR approaches PSInSAR as well as Small base line subset (SBAS) can be used to estimate earth surface deformation. The SBAS technique [2] is a DInSAR approach which uses a twelve or more number of repeat SAR acquisitions in different combinations of a properly chosen data (subsets) for generation of DInSAR interferograms using two pass interferometric approach. Finally it leads to the generation of mean deformation velocity maps and displacement time series. Herein, SBAS algorithm has been used for time series deformation estimation in the NW Himalayan region. ENVISAT ASAR IS2 swath data from 2003 to 2008 have been used for quantifying slow deformation. Himalayan region is a very active tectonic belt and active orogeny play a significant role in land deformation process [3]. Geomorphology in the region is unique and reacts to the climate change adversely bringing with land slides and subsidence. Settlements on the hill slopes are prone to land slides, landslips, rockslides and soil creep. These hazardous features have hampered the over all progress of the region as they obstruct the roads and flow of traffic, break communication, block flowing water in stream and create temporary reservoirs and also bring down lot of soil cover and thus add enormous silt and gravel to the streams. It has been observed that average deformation varies from -30.0 mm/year to 10 mm/year in the NW Himalayan region . References [1] Massonnet, D., Feigl, K.L.,Rossi, M. and Adragna, F. (1994) Radar interferometry mapping of

Large-baseline InSAR for precise topographic mapping: a framework for TanDEM-X large-baseline data

Directory of Open Access Journals (Sweden)

M. Pinheiro

2017-09-01

Full Text Available The global Digital Elevation Model (DEM resulting from the TanDEM-X mission provides information about the world topography with outstanding precision. In fact, performance analysis carried out with the already available data have shown that the global product is well within the requirements of 10 m absolute vertical accuracy and 2 m relative vertical accuracy for flat to moderate terrain. The mission's science phase took place from October 2014 to December 2015. During this phase, bistatic acquisitions with across-track separation between the two satellites up to 3.6 km at the equator were commanded. Since the relative vertical accuracy of InSAR derived elevation models is, in principle, inversely proportional to the system baseline, the TanDEM-X science phase opened the doors for the generation of elevation models with improved quality with respect to the standard product. However, the interferometric processing of the large-baseline data is troublesome due to the increased volume decorrelation and very high frequency of the phase variations. Hence, in order to fully profit from the increased baseline, sophisticated algorithms for the interferometric processing, and, in particular, for the phase unwrapping have to be considered. This paper proposes a novel dual-baseline region-growing framework for the phase unwrapping of the large-baseline interferograms. Results from two experiments with data from the TanDEM-X science phase are discussed, corroborating the expected increased level of detail of the large-baseline DEMs.

A survey of volcano deformation in the central Andes using InSAR: Evidence for deep, slow inflation

Science.gov (United States)

Pritchard, M. E.; Simons, M.

2001-12-01

We use interferometric synthetic aperture radar (InSAR) to survey about 50 volcanos of the central Andes (15-27o S) for deformation during the 1992-2000 time interval. Because of the remote location of these volcanos, the activity of most are poorly constrained. Using the ERS-1/2 C-band radars (5.6 cm), we observe good interferometric correlation south of about 21o S, but poor correlation north of that latitude, especially in southern Peru. This variation is presumably related to regional climate variations. Our survey reveals broad (10's of km), roughly axisymmetric deformation at 2 volcanic centers with no previously documented deformation. At Uturuncu volcano, in southwestern Bolivia, the deformation rate can be constrained with radar data from several satellite tracks and is about 1 cm/year between 1992 and 2000. We find a second source of volcanic deformation located between Lastarria and Cordon del Azufre volcanos near the Chile/Argentina border. There is less radar data to constrain the deformation in this area, but the rate is also about 1 cm/yr between 1996 and 2000. While the spatial character of the deformation field appears to be affected by atmosphere at both locations, we do not think that the entire signal is atmospheric, because the signal is observed in several interferograms and nearby edifices do not show similar patterns. The deformation signal appears to be time-variable, although it is difficult to determine whether this is due to real variations in the deformation source or atmospheric effects. We model the deformation with both a uniform point-source source of inflation, and a tri-axial point-source ellipsoid, and compare both elastic half-space and layered-space models. We also explore the effects of local topography upon the deformation field using the method of Williams and Wadge (1998). We invert for source parameters using the global search Neighborhood Algorithm of Sambridge (1998). Preliminary results indicate that the sources at both

Development and Evaluation of Science and Technology Education Program Using Interferometric SAR

Science.gov (United States)

Ito, Y.; Ikemitsu, H.; Nango, K.

2016-06-01

This paper proposes a science and technology education program to teach junior high school students to measure terrain changes by using interferometric synthetic aperture radar (SAR). The objectives of the proposed program are to evaluate and use information technology by performing SAR data processing in order to measure ground deformation, and to incorporate an understanding of Earth sciences by analyzing interferometric SAR processing results. To draft the teaching guidance plan for the developed education program, this study considers both science and technology education. The education program was used in a Japanese junior high school. An educational SAR processor developed by the authors and the customized Delft object-oriented radar interferometric software package were employed. Earthquakes as diastrophism events were chosen as practical teaching materials. The selected events indicate clear ground deformation in differential interferograms with high coherence levels. The learners were able to investigate the ground deformations and disasters caused by the events. They interactively used computers and became skilled at recognizing the knowledge and techniques of information technology, and then they evaluated the technology. Based on the results of pre- and post-questionnaire surveys and self-evaluation by the learners, it was clarified that the proposed program was applicable for junior high school education, and the learners recognized the usefulness of Earth observation technology by using interferometric SAR. The usefulness of the teaching materials in the learning activities was also shown through the practical teaching experience.

X-ray interferometric Fourier holography

International Nuclear Information System (INIS)

Balyan, M.K.

2016-01-01

The X-ray interferometric Fourier holography is proposed and theoretically investigated. Fourier The X-ray interferometric Young fringes and object image reconstruction are investigated. It is shown that the interference pattern of two slits formed on the exit surface of the crystal-analyzer (the third plate of the interferometer) is the X-ray interferometric Young fringes. An expression for X-ray interferometric Young fringes period is obtained. The subsequent reconstruction of the slit image as an object is performed by means of Fourier transform of the intensity distribution on the hologram. Three methods of reconstruction of the amplitude transmission complex function of the object are presented: analytical - approximate method, method of iteration and step by step method. As an example the X-ray Fourier interferometric hologram recording and the complex amplitude transmission function reconstruction for a beryllium circular wire are considered

Iterated unscented Kalman filter for phase unwrapping of interferometric fringes.

Science.gov (United States)

Xie, Xianming

2016-08-22

A fresh phase unwrapping algorithm based on iterated unscented Kalman filter is proposed to estimate unambiguous unwrapped phase of interferometric fringes. This method is the result of combining an iterated unscented Kalman filter with a robust phase gradient estimator based on amended matrix pencil model, and an efficient quality-guided strategy based on heap sort. The iterated unscented Kalman filter that is one of the most robust methods under the Bayesian theorem frame in non-linear signal processing so far, is applied to perform simultaneously noise suppression and phase unwrapping of interferometric fringes for the first time, which can simplify the complexity and the difficulty of pre-filtering procedure followed by phase unwrapping procedure, and even can remove the pre-filtering procedure. The robust phase gradient estimator is used to efficiently and accurately obtain phase gradient information from interferometric fringes, which is needed for the iterated unscented Kalman filtering phase unwrapping model. The efficient quality-guided strategy is able to ensure that the proposed method fast unwraps wrapped pixels along the path from the high-quality area to the low-quality area of wrapped phase images, which can greatly improve the efficiency of phase unwrapping. Results obtained from synthetic data and real data show that the proposed method can obtain better solutions with an acceptable time consumption, with respect to some of the most used algorithms.

Multi-decadal elevation changes on Bagley Ice Valley and Malaspina Glacier, Alaska

Science.gov (United States)

Muskett, Reginald R.; Lingle, Craig S.; Tangborn, Wendell V.; Rabus, Bernhard T.

2003-08-01

Digital elevation models (DEMs) of Bagley Ice Valley and Malaspina Glacier produced by (i) Intermap Technologies, Inc. (ITI) from airborne interferometric synthetic aperture radar (InSAR) data acquired 4-13 September 2000, (ii) the German Aerospace Center (DRL) from spaceborne InSAR data acquired by the Shuttle Radar Topography Mission (SRTM) 11-22 February 2000, and (iii) the US Geological Survey (USGS) from aerial photographs acquired in 1972/73, were differenced to estimate glacier surface elevation changes from 1972 to 2000. Spatially non-uniform thickening, 10 +/- 7 m on average, is observed on Bagley Ice Valley (accumulation area) while non-uniform thinning, 47 +/- 5 m on average, is observed on the glaciers of the Malaspina complex (mostly ablation area). Even larger thinning is observed on the retreating tidewater Tyndall Glacier. These changes have resulted from increased temperature and precipitation associated with climate warming, and rapid tidewater retreat.

Crustal Deformation Caused by Earthquake Detected by InSAR Technique Using ALOS/PALSAR Data

Science.gov (United States)

Miyagi, Y.; Nishimura, Y.; Takahashi, H.; Shimada, M.

2007-12-01

The Japan Aerospace Exploration Agency (JAXA) launched the Advanced Land Observing Satellite (ALOS), which is commonly called 'Daichi' in Japanese, on 24th January 2006. This satellite has the Phased Array type L- band Synthetic Aperture Radar (PALSAR) following the mission of the Japanese Earth Resource Satellite-1 (JERS-1). The PALSAR is an advanced SAR sensor with up to 10 m of spatial resolution and variable off-nadir angle. The ALOS/PALSAR can determine the position and attitude with high accuracy by use of mounted dual frequency GPS system and high precision star trackers, and L-band SAR sensor is suitable to observe even heavily-vegetated area. Therefore it is expected much better coherent SAR images than the JERS-1 and the other previous C-band SAR satellites, and major step forward for InSAR (Interferometric SAR) technique. Actually, several outstanding results from InSAR measurements have been reported for the period after the launch. In 2007, two big earthquakes causing some damages on the periphery occurred in Japan. One is M6.7 Noto Peninsula earthquake on 25th March 2007, and the other is M6.8 off the Chuetsu region earthquake on 16th July 2007. Because both seismic faults inferred from these earthquakes are located at shallow depth beneath the bottom of the sea near the coast, obvious crustal deformation in a land area were detected by PALSAR data. In Japan, there is a dense nation-wide GPS network (GEONET) composed of more than 1200 GPS sites established and operated by Geographical Survey Institute and a lot of seismometers. Similarly GPS and seismometer could detect signals caused by the earthquakes, so these are noticeable cases from the standpoint of a comparison among various kinds of data. A remote sensing technique like the ALOS/PALSAR has advantage to observe and monitor a disaster occurred in a remote location where it is difficult to get and there has been little geophysical observation. In this presentation, we notice the case of

Michelson interferometer vibrometer using self-correcting synthetic-heterodyne demodulation.

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Connelly, Michael J; Galeti, José Henrique; Kitano, Cláudio

2015-06-20

Synthetic-heterodyne demodulation is a useful technique for dynamic displacement and velocity detection in interferometric sensors, as it can provide an output signal that is immune to interferometric drift. With the advent of cost-effective, high-speed real-time signal-processing systems and software, processing of the complex signals encountered in interferometry has become more feasible. In synthetic heterodyne, to obtain the actual dynamic displacement or vibration of the object under test requires knowledge of the interferometer visibility and also the argument of two Bessel functions. In this paper, a method is described for determining the former and setting the Bessel function argument to a set value, which ensures maximum sensitivity. Conventional synthetic-heterodyne demodulation requires the use of two in-phase local oscillators; however, the relative phase of these oscillators relative to the interferometric signal is unknown. It is shown that, by using two additional quadrature local oscillators, a demodulated signal can be obtained that is independent of this phase difference. The experimental interferometer is a Michelson configuration using a visible single-mode laser, whose current is sinusoidally modulated at a frequency of 20 kHz. The detected interferometer output is acquired using a 250 kHz analog-to-digital converter and processed in real time. The system is used to measure the displacement sensitivity frequency response and linearity of a piezoelectric mirror shifter over a range of 500 Hz to 10 kHz. The experimental results show good agreement with two data-obtained independent techniques: the signal coincidence and denominated n-commuted Pernick method.

Absolute water storages in the Congo River floodplains from integration of InSAR and satellite radar altimetry

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Lee, H.; Yuan, T.; Jung, H. C.; Aierken, A.; Beighley, E.; Alsdorf, D. E.; Tshimanga, R.; Kim, D.

2017-12-01

Floodplains delay the transport of water, dissolved matter and sediments by storing water during flood peak seasons. Estimation of water storage over the floodplains is essential to understand the water balances in the fluvial systems and the role of floodplains in nutrient and sediment transport. However, spatio-temporal variations of water storages over floodplains are not well known due to their remoteness, vastness, and high temporal variability. In this study, we propose a new method to estimate absolute water storages over the floodplains by establishing relations between water depths (d) and water volumes (V) using 2-D water depth maps from the integration of Interferometric Synthetic Aperture Radar (InSAR) and altimetry measurements. We applied this method over the Congo River floodplains and modeled the d-V relation using a power function (note that d-V indicates relation between d and V, not d minus V), which revealed the cross-section geometry of the floodplains as a convex curve. Then, we combined this relation and Envisat altimetry measurements to construct time series of floodplain's absolute water storages from 2002 to 2011. Its mean annual amplitude over the floodplains ( 7,777 km2) is 3.860.59 km3 with peaks in December, which lags behind total water storage (TWS) changes from the Gravity Recovery and Climate Experiment (GRACE) and precipitation changes from Tropical Rainfall Measuring Mission (TRMM) by about one month. The results also exhibit inter-annual variability, with maximum water volume to be 5.9 +- 0.72 km3 in the wet year of 2002 and minimum volume to be 2.01 +- 0.63 km3 in the dry year of 2005. The inter-annual variation of water storages can be explained by the changes of precipitation from TRMM.

Image Registration Methode in Radar Interferometry

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S. Chelbi

2015-08-01

Full Text Available This article presents a methodology for the determination of the registration of an Interferometric Synthetic radar (InSAR pair images with half pixel precision. Using the two superposed radar images Single Look complexes (SLC [1-4], we developed an iterative process to superpose these two images according to their correlation coefficient with a high coherence area. This work concerns the exploitation of ERS Tandem pair of radar images SLC of the Algiers area acquired on 03 January and 04 January 1994. The former is taken as a master image and the latter as a slave image.

Post-Eruptive Inflation of Okmok Volcano, Alaska, from InSAR, 2008–2014

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Feifei Qu

2015-12-01

Full Text Available Okmok, a ~10-km wide caldera that occupies most of the northeastern end of Umnak Island, is one of the most active volcanoes in the Aleutian arc. The most recent eruption at Okmok during July–August 2008 was by far its largest and most explosive since at least the early 19th century. We investigate post-eruptive magma supply and storage at the volcano during 2008–2014 by analyzing all available synthetic aperture radar (SAR images of Okmok acquired during that time period using the multi-temporal InSAR technique. Data from the C-band Envisat and X-band TerraSAR-X satellites indicate that Okmok started inflating very soon after the end of 2008 eruption at a time-variable rate of 48–130 mm/y, consistent with GPS measurements. The “model-assisted” phase unwrapping method is applied to improve the phase unwrapping operation for long temporal baseline pairs. The InSAR time-series is used as input for deformation source modeling, which suggests magma accumulating at variable rates in a shallow storage zone at ~3.9 km below sea level beneath the summit caldera, consistent with previous studies. The modeled volume accumulation in the six years following the 2008 eruption is ~75% of the 1997 eruption volume and ~25% of the 2008 eruption volume.

Post-eruptive inflation of Okmok Volcano, Alaska, from InSAR, 2008–2014

Science.gov (United States)

Qu, Feifei; Lu, Zhong; Poland, Michael; Freymueller, Jeffrey T.; Zhang, Qin; Jung, Hyung-Sup

2016-01-01

Okmok, a ~10-km wide caldera that occupies most of the northeastern end of Umnak Island, is one of the most active volcanoes in the Aleutian arc. The most recent eruption at Okmok during July-August 2008 was by far its largest and most explosive since at least the early 19th century. We investigate post-eruptive magma supply and storage at the volcano during 2008–2014 by analyzing all available synthetic aperture radar (SAR) images of Okmok acquired during that time period using the multi-temporal InSAR technique. Data from the C-band Envisat and X-band TerraSAR-X satellites indicate that Okmok started inflating very soon after the end of 2008 eruption at a time-variable rate of 48-130 mm/y, consistent with GPS measurements. The “model-assisted” phase unwrapping method is applied to improve the phase unwrapping operation for long temporal baseline pairs. The InSAR time-series is used as input for deformation source modeling, which suggests magma accumulating at variable rates in a shallow storage zone at ~3.9 km below sea level beneath the summit caldera, consistent with previous studies. The modeled volume accumulation in the 6 years following the 2008 eruption is ~75% of the 1997 eruption volume and ~25% of the 2008 eruption volume.

Use of multitemporal InSAR data to develop geohazard scenarios for Bandung, Western Java, Indonesia

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Salvi, Stefano; Tolomei, Cristiano; Duro, Javier; Pezzo, Giuseppe; Koudogbo, Fifamè

2015-04-01

The Greater Bandung metropolitan area is the second largest urban area in Indonesia, with a population of 8.6 million. It is subject to a variety of geohazards: volcanic hazards from seven active volcanoes within a radius of 50 km; high flood hazards, seismic hazard due to crustal active faults, the best known being the 30-km long Lembang fault, 10 km North of the city centre; subsidence hazards due to strong aquifer depletion; landslide hazard in the surrounding high country. In the framework of the FP7 RASOR project, multitemporal satellite SAR data have been processed over Bandung, Western Java. We used the SBAS InSAR technique (Berardino et al., 2002) to process two ALOS-1 datasets, to investigate the various sources of surface deformation acting in the area in the period 2008-2011. Persistent Scatterer Interferometry (PSI) has also been applied to achieve ground motion measurements with millimetric precision and high accuracy. The PSI processing technique considers a system of points that reflect the radar signal from the satellite continuously through the time. It makes use of differential interferometric phase measurements to generate long term terrain deformation and digital surface model maps. The GlobalSARTM algorithms developed by Altamira Information are applied to COSMO-SkyMed data acquired to measure ground motion over the area of interest. Strong ground displacements (up to 7 cm/yr) due to groundwater abstraction have been measured in the Bandung basin. The identification of long wavelength signals from tectonic sources is difficult due to the limited InSAR coherence outside of the urban environment. Limited deformation is observed also in the Tangkuban Perahu volcano to the north. The spatial and temporal distribution of the ground motion is important supporting information for the generation of long term subsidence and flood hazard scenarios.

Advanced radar-interpretation of InSAR time series for mapping and characterization of geological processes

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F. Cigna

2011-03-01

Full Text Available We present a new post-processing methodology for the analysis of InSAR (Synthetic Aperture Radar Interferometry multi-temporal measures, based on the temporal under-sampling of displacement time series, the identification of potential changes occurring during the monitoring period and, eventually, the classification of different deformation behaviours. The potentials of this approach for the analysis of geological processes were tested on the case study of Naro (Italy, specifically selected due to its geological setting and related ground instability of unknown causes that occurred in February 2005. The time series analysis of past (ERS1/2 descending data; 1992–2000 and current (RADARSAT-1 ascending data; 2003–2007 ground movements highlighted significant displacement rates (up to 6 mm yr⁻¹ in 2003–2007, followed by a post-event stabilization. The deformational behaviours of instable areas involved in the 2005 event were also detected, clarifying typology and kinematics of ground instability. The urban sectors affected and unaffected by the event were finally mapped, consequently re-defining and enlarging the influenced area previously detected by field observations. Through the integration of InSAR data and conventional field surveys (i.e. geological, geomorphologic and geostructural campaigns, the causes of instability were finally attributed to tectonics.

Three-dimensional Reconstruction Method Study Based on Interferometric Circular SAR

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Hou Liying

2016-10-01

Full Text Available Circular Synthetic Aperture Radar (CSAR can acquire targets’ scattering information in all directions by a 360° observation, but a single-track CSAR cannot efficiently obtain height scattering information for a strong directive scatter. In this study, we examine the typical target of the three-dimensional circular SAR interferometry theoryand validate the theory in a darkroom experiment. We present a 3D reconstruction of the actual tank metal model of interferometric CSAR for the first time, verify the validity of the method, and demonstrate the important potential applications of combining 3D reconstruction with omnidirectional observation.

Sources of Artefacts in Synthetic Aperture Radar Interferometry Data Sets

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Becek, K.; Borkowski, A.

2012-07-01

In recent years, much attention has been devoted to digital elevation models (DEMs) produced using Synthetic Aperture Radar Interferometry (InSAR). This has been triggered by the relative novelty of the InSAR method and its world-famous product—the Shuttle Radar Topography Mission (SRTM) DEM. However, much less attention, if at all, has been paid to sources of artefacts in SRTM. In this work, we focus not on the missing pixels (null pixels) due to shadows or the layover effect, but rather on outliers that were undetected by the SRTM validation process. The aim of this study is to identify some of the causes of the elevation outliers in SRTM. Such knowledge may be helpful to mitigate similar problems in future InSAR DEMs, notably the ones currently being developed from data acquired by the TanDEM-X mission. We analysed many cross-sections derived from SRTM. These cross-sections were extracted over the elevation test areas, which are available from the Global Elevation Data Testing Facility (GEDTF) whose database contains about 8,500 runways with known vertical profiles. Whenever a significant discrepancy between the known runway profile and the SRTM cross-section was detected, a visual interpretation of the high-resolution satellite image was carried out to identify the objects causing the irregularities. A distance and a bearing from the outlier to the object were recorded. Moreover, we considered the SRTM look direction parameter. A comprehensive analysis of the acquired data allows us to establish that large metallic structures, such as hangars or car parking lots, are causing the outliers. Water areas or plain wet terrains may also cause an InSAR outlier. The look direction and the depression angle of the InSAR system in relation to the suspected objects influence the magnitude of the outliers. We hope that these findings will be helpful in designing the error detection routines of future InSAR or, in fact, any microwave aerial- or space-based survey. The

SOURCES OF ARTEFACTS IN SYNTHETIC APERTURE RADAR INTERFEROMETRY DATA SETS

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K. Becek

2012-07-01

Full Text Available In recent years, much attention has been devoted to digital elevation models (DEMs produced using Synthetic Aperture Radar Interferometry (InSAR. This has been triggered by the relative novelty of the InSAR method and its world-famous product—the Shuttle Radar Topography Mission (SRTM DEM. However, much less attention, if at all, has been paid to sources of artefacts in SRTM. In this work, we focus not on the missing pixels (null pixels due to shadows or the layover effect, but rather on outliers that were undetected by the SRTM validation process. The aim of this study is to identify some of the causes of the elevation outliers in SRTM. Such knowledge may be helpful to mitigate similar problems in future InSAR DEMs, notably the ones currently being developed from data acquired by the TanDEM-X mission. We analysed many cross-sections derived from SRTM. These cross-sections were extracted over the elevation test areas, which are available from the Global Elevation Data Testing Facility (GEDTF whose database contains about 8,500 runways with known vertical profiles. Whenever a significant discrepancy between the known runway profile and the SRTM cross-section was detected, a visual interpretation of the high-resolution satellite image was carried out to identify the objects causing the irregularities. A distance and a bearing from the outlier to the object were recorded. Moreover, we considered the SRTM look direction parameter. A comprehensive analysis of the acquired data allows us to establish that large metallic structures, such as hangars or car parking lots, are causing the outliers. Water areas or plain wet terrains may also cause an InSAR outlier. The look direction and the depression angle of the InSAR system in relation to the suspected objects influence the magnitude of the outliers. We hope that these findings will be helpful in designing the error detection routines of future InSAR or, in fact, any microwave aerial- or space

Basic to Advanced InSAR Processing: GMTSAR

Science.gov (United States)

Sandwell, D. T.; Xu, X.; Baker, S.; Hogrelius, A.; Mellors, R. J.; Tong, X.; Wei, M.; Wessel, P.

2017-12-01

Monitoring crustal deformation using InSAR is becoming a standard technique for the science and application communities. Optimal use of the new data streams from Sentinel-1 and NISAR will require open software tools as well as education on the strengths and limitations of the InSAR methods. Over the past decade we have developed freely available, open-source software for processing InSAR data. The software relies on the Generic Mapping Tools (GMT) for the back-end data analysis and display and is thus called GMTSAR. With startup funding from NSF, we accelerated the development of GMTSAR to include more satellite data sources and provide better integration and distribution with GMT. In addition, with support from UNAVCO we have offered 6 GMTSAR short courses to educate mostly novice InSAR users. Currently, the software is used by hundreds of scientists and engineers around the world to study deformation at more than 4300 different sites. The most challenging aspect of the recent software development was the transition from image alignment using the cross-correlation method to a completely new alignment algorithm that uses only the precise orbital information to geometrically align images to an accuracy of better than 7 cm. This development was needed to process a new data type that is being acquired by the Sentinel-1A/B satellites. This combination of software and open data is transforming radar interferometry from a research tool into a fully operational time series analysis tool. Over the next 5 years we are planning to continue to broaden the user base through: improved software delivery methods; code hardening; better integration with data archives; support for high level products being developed for NISAR; and continued education and outreach.

Potential of TCPInSAR in Monitoring Linear Infrastructure with a Small Dataset of SAR Images: Application of the Donghai Bridge, China

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Lei Zhang

2018-03-01

Full Text Available Reliably monitoring deformation associated with linear infrastructures, such as long-span bridges, is vitally important to assess their structural health. In this paper, we attempt to employ satellite interferometric synthetic aperture radar (InSAR to map the deformation of Donghai Bridge over a half of an annual cycle. The bridge, as the fourth longest cross-sea bridge in the world, located in the north of Hangzhou Bay, East China Sea where the featureless sea surface largely occupied the radar image raises challenges to accurately co-register the coherent points along the bridge. To tackle the issues due to co-registration and the limited number of synthetic aperture radar (SAR images, we adopt the termed temporarily-coherent point (TCP InSAR (TCPInSAR technique to process the radar images. TCPs that are not necessarily coherent during the whole observation period can be identified within every two SAR acquisitions during the co-registration procedure based on the statistics of azimuth and range offsets. In the process, co-registration is performed only using the offsets of these TCPs, leading to improved interferometric phases and the local Delaunay triangulation is used to construct point pairs to reduce the atmospheric artifacts along the bridge. With the TCPInSAR method the deformation rate along the bridge is estimated with no need of phase unwrapping. The achieved result reveals that the Donghai Bridge suffered a line-of-sight (LOS deformation rate up to −2.3 cm/year from January 2009 to July 2009 at the cable-stayed part, which is likely due to the thermal expansion of cables.

Robust snapshot interferometric spectropolarimetry.

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Kim, Daesuk; Seo, Yoonho; Yoon, Yonghee; Dembele, Vamara; Yoon, Jae Woong; Lee, Kyu Jin; Magnusson, Robert

2016-05-15

This Letter describes a Stokes vector measurement method based on a snapshot interferometric common-path spectropolarimeter. The proposed scheme, which employs an interferometric polarization-modulation module, can extract the spectral polarimetric parameters Ψ(k) and Δ(k) of a transmissive anisotropic object by which an accurate Stokes vector can be calculated in the spectral domain. It is inherently strongly robust to the object 3D pose variation, since it is designed distinctly so that the measured object can be placed outside of the interferometric module. Experiments are conducted to verify the feasibility of the proposed system. The proposed snapshot scheme enables us to extract the spectral Stokes vector of a transmissive anisotropic object within tens of msec with high accuracy.

Dynamics of Kilauea's Magmatic System Imaged Using a Joint Analysis of Geodetic and Seismic Data

Science.gov (United States)

Wauthier, C.; Roman, D. C.; Poland, M. P.; Fukushima, Y.; Hooper, A. J.

2012-12-01

Nowadays, Interferometric Synthetic Aperture Radar (InSAR) is commonly used to study a wide range of active volcanic areas. InSAR provides high-spatial-resolution measurements of surface deformation with centimeter-scale accuracy. At Kilauea Volcano, Hawai'i, InSAR shows complex processes that are not well constrained by GPS data (which have relatively poor spatial resolution). However, GPS data have higher temporal resolution than InSAR data. Both datasets are thus complementary. To overcome some of the limitations of conventional InSAR, which are mainly induced by temporal decorrelation, topographic, orbital and atmospheric delays, a Multi-Temporal InSAR (MT-InSAR) approach can be used. MT-InSAR techniques involve the processing of multiple SAR acquisitions over the same area. Two classes of MT-InSAR algorithms are defined: the persistent scatterers (PS) and small baseline (SBAS) methods. Each method is designed for a specific type of scattering mechanism. A PS pixel is a pixel in which a single scatterer dominates, while the contributions from other scatterers are negligible. A SBAS pixel is a pixel that includes distributed scatterers, which have a phase with little decorrelation over short time periods. Here, we apply the "StaMPS" ("Stanford Method for Permanent Scatterers") technique, which incorporates both a PS and SBAS approach, on ENVISAT and ALOS datasets acquired from 2003 to 2010 at Kilauea. In particular, we focus our InSAR analysis on the time period before the June 2007 "Father's Day" dike intrusion and eruption, and also incorporate seismic and GPS data in our models. Our goal is to identify any precursors to the Father's Day event within Kilauea's summit magma system, east rift zone, and/or southwest rift zone.

Assimilating InSAR Maps of Water Vapor to Improve Heavy Rainfall Forecasts: A Case Study With Two Successive Storms

Science.gov (United States)

Mateus, Pedro; Miranda, Pedro M. A.; Nico, Giovanni; Catalão, João.; Pinto, Paulo; Tomé, Ricardo

2018-04-01

Very high resolution precipitable water vapor maps obtained by the Sentinel-1 A synthetic aperture radar (SAR), using the SAR interferometry (InSAR) technique, are here shown to have a positive impact on the performance of severe weather forecasts. A case study of deep convection which affected the city of Adra, Spain, on 6-7 September 2015, is successfully forecasted by the Weather Research and Forecasting model initialized with InSAR data assimilated by the three-dimensional variational technique, with improved space and time distributions of precipitation, as observed by the local weather radar and rain gauge. This case study is exceptional because it consisted of two severe events 12 hr apart, with a timing that allows for the assimilation of both the ascending and descending satellite images, each for the initialization of each event. The same methodology applied to the network of Global Navigation Satellite System observations in Iberia, at the same times, failed to reproduce observed precipitation, although it also improved, in a more modest way, the forecast skill. The impact of precipitable water vapor data is shown to result from a direct increment of convective available potential energy, associated with important adjustments in the low-level wind field, favoring its release in deep convection. It is suggested that InSAR images, complemented by dense Global Navigation Satellite System data, may provide a new source of water vapor data for weather forecasting, since their sampling frequency could reach the subdaily scale by merging different SAR platforms, or when future geosynchronous radar missions become operational.

Interferometric SAR and land deformation. Analysis using the dislocation model; Interferometric SAR to chikaku hendo. Dislocation model wo mochiita kaiseki

Energy Technology Data Exchange (ETDEWEB)

Matsushima, J; Otaki, T; Tanaka, A; Miyazaki, Y [Geological Survey of Japan, Tsukuba (Japan)

1996-05-01

The diastrophism by the earthquake-induced dislocation is investigated by interferometry (INSAR) which represents the diastrophism by the interference fringes of equiphase difference lines. A joint research group at Geographical Survey Institute and National Space Development Agency showed the diastrophism in the vicinity of the ground surfaces before and after the Hyogoken Nanbu Earthquake by the INSAR interference images in 1995. This paper discusses the effects of observation in the vision line direction from the satellite and dislocation parameters on the interference images. The dislocation model uses a slanted rectangular model in a semi-infinite medium, to calculate static displacements and strain distributions at the ground surface, when dislocation changes. It is found that the INSAR interference images, detecting displacements in the vision line direction from the satellite, significantly change as the vision line direction changes, and that the actual displacement cannot be given by the images alone. This paper also shows sensitivity of the interference images to the dislocation parameters. 3 refs., 9 figs., 1 tab.

Interferometric snapshot spectro-ellipsometry.

Science.gov (United States)

Dembele, Vamara; Jin, Moonseob; Choi, Inho; Chegal, Won; Kim, Daesuk

2018-01-22

We propose a snapshot spectroscopic ellipsometry and its applications for real-time thin-film thickness measurement. The proposed system employs an interferometric polarization-modulation module that can measure the spectroscopic ellipsometric phase for thin-film deposited on a substrate with a measurement speed of around 20 msec. It requires neither moving parts nor time dependent modulation devices. The accuracy of the proposed interferometric snapshot spectro-ellipsometer is analyzed through comparison with commercial equipment results.

An Improved Interferometric Calibration Method Based on Independent Parameter Decomposition

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Fan, J.; Zuo, X.; Li, T.; Chen, Q.; Geng, X.

2018-04-01

Interferometric SAR is sensitive to earth surface undulation. The accuracy of interferometric parameters plays a significant role in precise digital elevation model (DEM). The interferometric calibration is to obtain high-precision global DEM by calculating the interferometric parameters using ground control points (GCPs). However, interferometric parameters are always calculated jointly, making them difficult to decompose precisely. In this paper, we propose an interferometric calibration method based on independent parameter decomposition (IPD). Firstly, the parameters related to the interferometric SAR measurement are determined based on the three-dimensional reconstruction model. Secondly, the sensitivity of interferometric parameters is quantitatively analyzed after the geometric parameters are completely decomposed. Finally, each interferometric parameter is calculated based on IPD and interferometric calibration model is established. We take Weinan of Shanxi province as an example and choose 4 TerraDEM-X image pairs to carry out interferometric calibration experiment. The results show that the elevation accuracy of all SAR images is better than 2.54 m after interferometric calibration. Furthermore, the proposed method can obtain the accuracy of DEM products better than 2.43 m in the flat area and 6.97 m in the mountainous area, which can prove the correctness and effectiveness of the proposed IPD based interferometric calibration method. The results provide a technical basis for topographic mapping of 1 : 50000 and even larger scale in the flat area and mountainous area.

Urban Monitoring Based on SENTINEL-1 Data Using Permanent Scatterer Interferometry and SAR Tomography

Science.gov (United States)

Crosetto, M.; Budillon, A.; Johnsy, A.; Schirinzi, G.; Devanthéry, N.; Monserrat, O.; Cuevas-González, M.

2018-04-01

A lot of research and development has been devoted to the exploitation of satellite SAR images for deformation measurement and monitoring purposes since Differential Interferometric Synthetic Apertura Radar (InSAR) was first described in 1989. In this work, we consider two main classes of advanced DInSAR techniques: Persistent Scatterer Interferometry and Tomographic SAR. Both techniques make use of multiple SAR images acquired over the same site and advanced procedures to separate the deformation component from the other phase components, such as the residual topographic component, the atmospheric component, the thermal expansion component and the phase noise. TomoSAR offers the advantage of detecting either single scatterers presenting stable proprieties over time (Persistent Scatterers) and multiple scatterers interfering within the same range-azimuth resolution cell, a significant improvement for urban areas monitoring. This paper addresses a preliminary inter-comparison of the results of both techniques, for a test site located in the metropolitan area of Barcelona (Spain), where interferometric Sentinel-1 data were analysed.

Causes of unrest at silicic calderas in the East African Rift: New constraints from InSAR and soil-gas chemistry at Aluto volcano, Ethiopia

Science.gov (United States)

Hutchison, William; Biggs, Juliet; Mather, Tamsin A.; Pyle, David M.; Lewi, Elias; Yirgu, Gezahegn; Caliro, Stefano; Chiodini, Giovanni; Clor, Laura E.; Fischer, Tobias P.

2016-08-01

Restless silicic calderas present major geological hazards, and yet many also host significant untapped geothermal resources. In East Africa, this poses a major challenge, although the calderas are largely unmonitored their geothermal resources could provide substantial economic benefits to the region. Understanding what causes unrest at these volcanoes is vital for weighing up the opportunities against the potential risks. Here we bring together new field and remote sensing observations to evaluate causes of ground deformation at Aluto, a restless silicic volcano located in the Main Ethiopian Rift (MER). Interferometric Synthetic Aperture Radar (InSAR) data reveal the temporal and spatial characteristics of a ground deformation episode that took place between 2008 and 2010. Deformation time series reveal pulses of accelerating uplift that transition to gradual long-term subsidence, and analytical models support inflation source depths of ˜5 km. Gases escaping along the major fault zone of Aluto show high CO2 flux, and a clear magmatic carbon signature (CO2-δ13C of -4.2‰ to -4.5‰). This provides compelling evidence that the magmatic and hydrothermal reservoirs of the complex are physically connected. We suggest that a coupled magmatic-hydrothermal system can explain the uplift-subsidence signals. We hypothesize that magmatic fluid injection and/or intrusion in the cap of the magmatic reservoir drives edifice-wide inflation while subsequent deflation is related to magmatic degassing and depressurization of the hydrothermal system. These new constraints on the plumbing of Aluto yield important insights into the behavior of rift volcanic systems and will be crucial for interpreting future patterns of unrest.

AN IMPROVED INTERFEROMETRIC CALIBRATION METHOD BASED ON INDEPENDENT PARAMETER DECOMPOSITION

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J. Fan

2018-04-01

Full Text Available Interferometric SAR is sensitive to earth surface undulation. The accuracy of interferometric parameters plays a significant role in precise digital elevation model (DEM. The interferometric calibration is to obtain high-precision global DEM by calculating the interferometric parameters using ground control points (GCPs. However, interferometric parameters are always calculated jointly, making them difficult to decompose precisely. In this paper, we propose an interferometric calibration method based on independent parameter decomposition (IPD. Firstly, the parameters related to the interferometric SAR measurement are determined based on the three-dimensional reconstruction model. Secondly, the sensitivity of interferometric parameters is quantitatively analyzed after the geometric parameters are completely decomposed. Finally, each interferometric parameter is calculated based on IPD and interferometric calibration model is established. We take Weinan of Shanxi province as an example and choose 4 TerraDEM-X image pairs to carry out interferometric calibration experiment. The results show that the elevation accuracy of all SAR images is better than 2.54 m after interferometric calibration. Furthermore, the proposed method can obtain the accuracy of DEM products better than 2.43 m in the flat area and 6.97 m in the mountainous area, which can prove the correctness and effectiveness of the proposed IPD based interferometric calibration method. The results provide a technical basis for topographic mapping of 1 : 50000 and even larger scale in the flat area and mountainous area.

Accelerated Scientific InSAR Processing, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Neva Ridge Technologies proposes to develop a suite of software tools for the analysis of SAR and InSAR data, focused on having a robust and adopted capability well...

Interferometric crosstalk reduction by phase scrambling

NARCIS (Netherlands)

Tafur Monroy, I.; Tangdiongga, E.; Jonker, R.J.W.; Waardt, de H.

2000-01-01

Interferometric crosstalk, arising from the detection of undesired signals at the same nominal wavelength, may introduce large power penalties and bit-error rate (BER) floor significantly restricting the scalability of optical networks. In this paper, interferometric crosstalk reduction in optical

Assessing deformation and morphology of Arctic landfast sea ice using InSAR to support use and management of coastal ice

Science.gov (United States)

Dammann, D. O.; Eicken, H.; Meyer, F. J.; Mahoney, A. R.

2016-12-01

Arctic landfast sea ice provides important services to people, including coastal communities and industry, as well as key marine biota. In many regions of the Arctic, the use of landfast sea ice by all stakeholders is increasingly limited by reduced stability of the ice cover, which results in more deformation and rougher ice conditions as well as reduced extent and an increased likelihood of detachment from the shore. Here, we use Synthetic Aperture Radar Interferometry (InSAR) to provide stakeholder-relevant data on key constraints for sea ice use, in particular ice stability and morphology, which are difficult to assess using conventional SAR. InSAR has the capability to detect small-scale landfast ice displacements, which are linked to important coastal hazards, including the formation of cracks, ungrounding of ice pressure ridges, and catastrophic breakout events. While InSAR has previously been used to identify the extent of landfast ice and regions of deformation within, quantitative analysis of small-scale ice motion has yet to be thoroughly validated and its potential remains largely underutilized in sea ice science. Using TanDEM-X interferometry, we derive surface displacements of landfast ice within Elson Lagoon near Barrow, Alaska, which we validate using in-situ DGPS data. We then apply an inverse model to estimate rates and patterns of shorefast ice deformation in other regions of landfast ice using interferograms generated with long-temporal baseline L-band ALOS-1 PALSAR-1 data. The model is able to correctly identify deformation modes and proxies for the associated relative internal elastic stress. The derived potential for fractures corresponds well with large-scale sea ice patterns and local in-situ observations. The utility of InSAR to quantify sea ice roughness has also been explored using TanDEM-X bistatic interferometry, which eliminates the effects of temporal changes in the ice cover. The InSAR-derived DEM shows good correlation with a high

Interferometric redatuming by sparse inversion

Science.gov (United States)

van der Neut, Joost; Herrmann, Felix J.

2013-02-01

Assuming that transmission responses are known between the surface and a particular depth level in the subsurface, seismic sources can be effectively mapped to this level by a process called interferometric redatuming. After redatuming, the obtained wavefields can be used for imaging below this particular depth level. Interferometric redatuming consists of two steps, namely (i) the decomposition of the observed wavefields into downgoing and upgoing constituents and (ii) a multidimensional deconvolution of the upgoing constituents with the downgoing constituents. While this method works in theory, sensitivity to noise and artefacts due to incomplete acquisition require a different formulation. In this letter, we demonstrate the benefits of formulating the two steps that undergird interferometric redatuming in terms of a transform-domain sparsity-promoting program. By exploiting compressibility of seismic wavefields in the curvelet domain, the method not only becomes robust with respect to noise but we are also able to remove certain artefacts while preserving the frequency content. Although we observe improvements when we promote sparsity in the redatumed data space, we expect better results when interferometric redatuming would be combined or integrated with least-squares migration with sparsity promotion in the image space.

The Ecosystems SAR (EcoSAR) an Airborne P-band Polarimetric InSAR for the Measurement of Vegetation Structure, Biomass and Permafrost

Science.gov (United States)

Rincon, Rafael F.; Fatoyinbo, Temilola; Ranson, K. Jon; Osmanoglu, Batuhan; Sun, Guoqing; Deshpande, Manohar D.; Perrine, Martin L.; Du Toit, Cornelis F.; Bonds, Quenton; Beck, Jaclyn;

MEMS Gyroscope with Interferometric Detection, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The proposed innovation is a novel MEMS gyroscope that uses micro-interferometric detection to measure the motion of the proof mass. Using an interferometric...

Modelling above Ground Biomass in Tanzanian Miombo Woodlands Using TanDEM-X WorldDEM and Field Data

Directory of Open Access Journals (Sweden)

Stefano Puliti

2017-09-01

Full Text Available The use of Interferometric Synthetic Aperture Radar (InSAR data has great potential for monitoring large scale forest above ground biomass (AGB in the tropics due to the increased ability to retrieve 3D information even under cloud cover. To date; results in tropical forests have been inconsistent and further knowledge on the accuracy of models linking AGB and InSAR height data is crucial for the development of large scale forest monitoring programs. This study provides an example of the use of TanDEM-X WorldDEM data to model AGB in Tanzanian woodlands. The primary objective was to assess the accuracy of a model linking AGB with InSAR height from WorldDEM after the subtraction of ground heights. The secondary objective was to assess the possibility of obtaining InSAR height for field plots when the terrain heights were derived from global navigation satellite systems (GNSS; i.e., as an alternative to using airborne laser scanning (ALS. The results revealed that the AGB model using InSAR height had a predictive accuracy of R M S E = 24.1 t·ha−1; or 38.8% of the mean AGB when terrain heights were derived from ALS. The results were similar when using terrain heights from GNSS. The accuracy of the predicted AGB was improved when compared to a previous study using TanDEM-X for a sub-area of the area of interest and was of similar magnitude to what was achieved in the same sub-area using ALS data. Overall; this study sheds new light on the opportunities that arise from the use of InSAR data for large scale AGB modelling in tropical woodlands.

Phase correction and error estimation in InSAR time series analysis

Science.gov (United States)

Zhang, Y.; Fattahi, H.; Amelung, F.

2017-12-01

During the last decade several InSAR time series approaches have been developed in response to the non-idea acquisition strategy of SAR satellites, such as large spatial and temporal baseline with non-regular acquisitions. The small baseline tubes and regular acquisitions of new SAR satellites such as Sentinel-1 allows us to form fully connected networks of interferograms and simplifies the time series analysis into a weighted least square inversion of an over-determined system. Such robust inversion allows us to focus more on the understanding of different components in InSAR time-series and its uncertainties. We present an open-source python-based package for InSAR time series analysis, called PySAR (https://yunjunz.github.io/PySAR/), with unique functionalities for obtaining unbiased ground displacement time-series, geometrical and atmospheric correction of InSAR data and quantifying the InSAR uncertainty. Our implemented strategy contains several features including: 1) improved spatial coverage using coherence-based network of interferograms, 2) unwrapping error correction using phase closure or bridging, 3) tropospheric delay correction using weather models and empirical approaches, 4) DEM error correction, 5) optimal selection of reference date and automatic outlier detection, 6) InSAR uncertainty due to the residual tropospheric delay, decorrelation and residual DEM error, and 7) variance-covariance matrix of final products for geodetic inversion. We demonstrate the performance using SAR datasets acquired by Cosmo-Skymed and TerraSAR-X, Sentinel-1 and ALOS/ALOS-2, with application on the highly non-linear volcanic deformation in Japan and Ecuador (figure 1). Our result shows precursory deformation before the 2015 eruptions of Cotopaxi volcano, with a maximum uplift of 3.4 cm on the western flank (fig. 1b), with a standard deviation of 0.9 cm (fig. 1a), supporting the finding by Morales-Rivera et al. (2017, GRL); and a post-eruptive subsidence on the same

Imaging irregular magma reservoirs with InSAR and GPS observations: Application to Kilauea and Copahue volcanoes

Science.gov (United States)

Lundgren, P.; Camacho, A.; Poland, M. P.; Miklius, A.; Samsonov, S. V.; Milillo, P.

2013-12-01

The availability of synthetic aperture radar (SAR) interferometry (InSAR) data has increased our awareness of the complexity of volcano deformation sources. InSAR's spatial completeness helps identify or clarify source process mechanisms at volcanoes (i.e. Mt. Etna east flank motion; Lazufre crustal magma body; Kilauea dike complexity) and also improves potential model realism. In recent years, Bayesian inference methods have gained widespread use because of their ability to constrain not only source model parameters, but also their uncertainties. They are computationally intensive, however, which tends to limit them to a few geometrically rather simple source representations (for example, spheres). An alternative approach involves solving for irregular pressure and/or density sources from a three-dimensional (3-D) grid of source/density cells. This method has the ability to solve for arbitrarily shaped bodies of constant absolute pressure/density difference. We compare results for both Bayesian (a Markov chain Monte Carlo algorithm) and the irregular source methods for two volcanoes: Kilauea, Hawaii, and Copahue, Argentina-Chile border. Kilauea has extensive InSAR and GPS databases from which to explore the results for the irregular method with respect to the Bayesian approach, prior models, and an extensive set of ancillary data. One caveat, however, is the current restriction in the irregular model inversion to volume-pressure sources (and at a single excess pressure change), which limits its application in cases where sources such as faults or dikes are present. Preliminary results for Kilauea summit deflation during the March 2011 Kamoamoa eruption suggests a northeast-elongated magma body lying roughly 1-1.5 km below the surface. Copahue is a southern Andes volcano that has been inflating since early 2012, with intermittent summit eruptive activity since late 2012. We have an extensive InSAR time series from RADARSAT-2 and COSMO-SkyMed data, although both are

Combined Use of C- and X-Band SAR Data for Subsidence Monitoring in an Urban Area

Directory of Open Access Journals (Sweden)

Lorenzo Solari

2017-04-01

Full Text Available In this study, we present the detection and characterization of ground displacements in the urban area of Pisa (Central Italy using Interferometric Synthetic Aperture Radar (InSAR products. Thirty RADARSAT-2 and twenty-nine COSMO-SkyMed images have been analyzed with the Small BAseline Subset (SBAS algorithm, in order to quantify the ground subsidence and its temporal evolution in the three-year time interval from 2011 to 2014. A borehole database was reclassified in stratigraphical and geotechnical homogeneous units, providing the geological background needed for the local scale analysis of the recorded displacements. Moreover, the interferometric outputs were compared with the last 30 years’ urban evolution of selected parts of the city. Two deformation patterns were recorded by the InSAR data: very slow vertical movements within the defined stability threshold (±2.5 mm/yr and areas with subsidence rates down to −5 to −7 mm/yr, associated with high peak velocities (−15 to −20 mm/yr registered by single buildings or small groups of buildings. Some of these structures are used to demonstrate that the high subsidence rates are related to the recent urbanization, which is the trigger for the accelerated consolidation process of highly compressible layers. Finally, this urban area was a valuable test site for demonstrating the different results of the C- and X-band data processing, in terms of the density of points and the quality of the time series of deformation.

A Robust and Multi-Weighted Approach to Estimating Topographically Correlated Tropospheric Delays in Radar Interferograms

Directory of Open Access Journals (Sweden)

Bangyan Zhu

2016-07-01

Full Text Available Spatial and temporal variations in the vertical stratification of the troposphere introduce significant propagation delays in interferometric synthetic aperture radar (InSAR observations. Observations of small amplitude surface deformations and regional subsidence rates are plagued by tropospheric delays, and strongly correlated with topographic height variations. Phase-based tropospheric correction techniques assuming a linear relationship between interferometric phase and topography have been exploited and developed, with mixed success. Producing robust estimates of tropospheric phase delay however plays a critical role in increasing the accuracy of InSAR measurements. Meanwhile, few phase-based correction methods account for the spatially variable tropospheric delay over lager study regions. Here, we present a robust and multi-weighted approach to estimate the correlation between phase and topography that is relatively insensitive to confounding processes such as regional subsidence over larger regions as well as under varying tropospheric conditions. An expanded form of robust least squares is introduced to estimate the spatially variable correlation between phase and topography by splitting the interferograms into multiple blocks. Within each block, correlation is robustly estimated from the band-filtered phase and topography. Phase-elevation ratios are multiply- weighted and extrapolated to each persistent scatter (PS pixel. We applied the proposed method to Envisat ASAR images over the Southern California area, USA, and found that our method mitigated the atmospheric noise better than the conventional phase-based method. The corrected ground surface deformation agreed better with those measured from GPS.

Mapping three-dimensional surface deformation by combining multiple-aperture interferometry and conventional interferometry: Application to the June 2007 eruption of Kilauea Volcano, Hawaii

Science.gov (United States)

Jung, H.-S.; Lu, Z.; Won, J.-S.; Poland, Michael P.; Miklius, Asta

2011-01-01

Surface deformation caused by an intrusion and small eruption during June 17-19, 2007, along the East Rift Zone of Kilauea Volcano, Hawaii, was three-dimensionally reconstructed from radar interferograms acquired by the Advanced Land Observing Satellite (ALOS) phased-array type L-band synthetic aperture radar (SAR) (PALSAR) instrument. To retrieve the 3-D surface deformation, a method that combines multiple-aperture interferometry (MAI) and conventional interferometric SAR (InSAR) techniques was applied to one ascending and one descending ALOS PALSAR interferometric pair. The maximum displacements as a result of the intrusion and eruption are about 0.8, 2, and 0.7 m in the east, north, and up components, respectively. The radar-measured 3-D surface deformation agrees with GPS data from 24 sites on the volcano, and the root-mean-square errors in the east, north, and up components of the displacement are 1.6, 3.6, and 2.1 cm, respectively. Since a horizontal deformation of more than 1 m was dominantly in the north-northwest-south-southeast direction, a significant improvement of the north-south component measurement was achieved by the inclusion of MAI measurements that can reach a standard deviation of 3.6 cm. A 3-D deformation reconstruction through the combination of conventional InSAR and MAI will allow for better modeling, and hence, a more comprehensive understanding, of the source geometry associated with volcanic, seismic, and other processes that are manifested by surface deformation.

Interferometric redatuming by sparse inversion

OpenAIRE

Van der Neut, J.; Herrmann, F.J.

2012-01-01

Assuming that transmission responses are known between the surface and a particular depth level in the subsurface, seismic sources can be effectively mapped to this level by a process called interferometric redatuming. After redatuming, the obtained wavefields can be used for imaging below this particular depth level. Interferometric redatuming consists of two steps, namely (i) the decomposition of the observed wavefields into downgoing and upgoing constituents and (ii) a multidimensional dec...

Analysis of Land Subsidence Monitoring in Mining Area with Time-Series Insar Technology

Science.gov (United States)

Sun, N.; Wang, Y. J.

2018-04-01

Time-series InSAR technology has become a popular land subsidence monitoring method in recent years, because of its advantages such as high accuracy, wide area, low expenditure, intensive monitoring points and free from accessibility restrictions. In this paper, we applied two kinds of satellite data, ALOS PALSAR and RADARSAT-2, to get the subsidence monitoring results of the study area in two time periods by time-series InSAR technology. By analyzing the deformation range, rate and amount, the time-series analysis of land subsidence in mining area was realized. The results show that InSAR technology could be used to monitor land subsidence in large area and meet the demand of subsidence monitoring in mining area.

The InSAR Scientific Computing Environment (ISCE): A Python Framework for Earth Science

Science.gov (United States)

Rosen, P. A.; Gurrola, E. M.; Agram, P. S.; Sacco, G. F.; Lavalle, M.

2015-12-01

The InSAR Scientific Computing Environment (ISCE, funded by NASA ESTO) provides a modern computing framework for geodetic image processing of InSAR data from a diverse array of radar satellites and aircraft. ISCE is both a modular, flexible, and extensible framework for building software components and applications as well as a toolbox of applications for processing raw or focused InSAR and Polarimetric InSAR data. The ISCE framework contains object-oriented Python components layered to construct Python InSAR components that manage legacy Fortran/C InSAR programs. Components are independently configurable in a layered manner to provide maximum control. Polymorphism is used to define a workflow in terms of abstract facilities for each processing step that are realized by specific components at run-time. This enables a single workflow to work on either raw or focused data from all sensors. ISCE can serve as the core of a production center to process Level-0 radar data to Level-3 products, but is amenable to interactive processing approaches that allow scientists to experiment with data to explore new ways of doing science with InSAR data. The NASA-ISRO SAR (NISAR) Mission will deliver data of unprecedented quantity and quality, making possible global-scale studies in climate research, natural hazards, and Earth's ecosystems. ISCE is planned as the foundational element in processing NISAR data, enabling a new class of analyses that take greater advantage of the long time and large spatial scales of these new data. NISAR will be but one mission in a constellation of radar satellites in the future delivering such data. ISCE currently supports all publicly available strip map mode space-borne SAR data since ERS and is expected to include support for upcoming missions. ISCE has been incorporated into two prototype cloud-based systems that have demonstrated its elasticity in addressing larger data processing problems in a "production" context and its ability to be

Radar image and data fusion for natural hazards characterisation

Science.gov (United States)

Lu, Zhong; Dzurisin, Daniel; Jung, Hyung-Sup; Zhang, Jixian; Zhang, Yonghong

2010-01-01

Fusion of synthetic aperture radar (SAR) images through interferometric, polarimetric and tomographic processing provides an all - weather imaging capability to characterise and monitor various natural hazards. This article outlines interferometric synthetic aperture radar (InSAR) processing and products and their utility for natural hazards characterisation, provides an overview of the techniques and applications related to fusion of SAR/InSAR images with optical and other images and highlights the emerging SAR fusion technologies. In addition to providing precise land - surface digital elevation maps, SAR - derived imaging products can map millimetre - scale elevation changes driven by volcanic, seismic and hydrogeologic processes, by landslides and wildfires and other natural hazards. With products derived from the fusion of SAR and other images, scientists can monitor the progress of flooding, estimate water storage changes in wetlands for improved hydrological modelling predictions and assessments of future flood impacts and map vegetation structure on a global scale and monitor its changes due to such processes as fire, volcanic eruption and deforestation. With the availability of SAR images in near real - time from multiple satellites in the near future, the fusion of SAR images with other images and data is playing an increasingly important role in understanding and forecasting natural hazards.

Multi-temporal and Dual-polarization Interferometric SAR for Land Cover Type Classification

Directory of Open Access Journals (Sweden)

WANG Xinshuang

2015-05-01

Full Text Available In order to study SAR land cover classification method, this paper uses the multi-dimensional combination of temporal,polarization and InSAR data. The area covered by space borne data of ALOS PALSAR in Xunke County,Heilongjiang Province was chosen as test site. A land cover classification technique of SVM based on multi-temporal, multi-polarization and InSAR data had been proposed, using the sensitivity to land cover type of multi-temporal, multi-polarization SAR data and InSAR measurements, and combing time series characteristic of backscatter coefficient and correlation coefficient to identify ground objects. The results showed the problem of confusion between forest land and urban construction land can be nicely solved, using the correlation coefficient between HH and HV, and also combing the selected temporal, polarization and InSAR characteristics. The land cover classification result with higher accuracy is gotten using the classification algorithm proposed in this paper.

High-resolution InSAR constraints on flood-related subsidence and evaporite dissolution along the Dead Sea shores: Interplay between hydrology and rheology

Science.gov (United States)

Shviro, Maayan; Haviv, Itai; Baer, Gidon

2017-09-01

Sinkhole generation and land subsidence are commonly attributed to dissolution of subsurface layers by under-saturated groundwater and formation of cavities. Along the Dead Sea (DS) shorelines, this process also involves seasonal flash floods that are drained into the subsurface by existing and newly formed sinkholes. We quantify the contribution of flash-floods to salt dissolution and land subsidence using high-resolution interferometric synthetic aperture radar (InSAR). Subsidence rates during a 3-year period (2012-2015) were calculated from 57 COSMO SkyMed X-band interferograms bracketing major flood events and intra-flood periods in 21 sinkhole sites. The sites are located within channels and alluvial fans along the western shores of the Dead Sea, Israel. The observed subsidence reaches maximum rates of 2.5 mm/day, accumulating in specific sites to 500 mm/year. In most of the sinkhole sites a gradual increase in the annual subsidence rate is observed during the 3-year study period. Three different modes of response to floods were observed: (1) sites where floodwater is not directly channeled into sinkholes do not respond to floods; (2) sites adjacent to active channels with sinkholes are unaffected by specific floods but their subsidence rates increase gradually from early winter to mid-summer, and decay gradually until the following winter; and (3) sites in active channels with sinkholes are characterized by an abrupt increase in subsidence rates immediately after each flood (by a factor of up to 20) and by a subsequent quasi-exponential subsidence decay over periods of several months. In these latter sites, subsidence rates after each flood are temporally correlated with alternating groundwater levels in adjacent boreholes. The rapid rise in groundwater head following floods increases the hydraulic gradient of the under-saturated groundwater and hence also the groundwater discharge and the dissolution rate of the subsurface salt layer. A subsequent quasi

Parametric estimation of time varying baselines in airborne interferometric SAR

DEFF Research Database (Denmark)

Mohr, Johan Jacob; Madsen, Søren Nørvang

1996-01-01

A method for estimation of time varying spatial baselines in airborne interferometric synthetic aperture radar (SAR) is described. The range and azimuth distortions between two images acquired with a non-linear baseline are derived. A parametric model of the baseline is then, in a least square...... sense, estimated from image shifts obtained by cross correlation of numerous small patches throughout the image. The method has been applied to airborne EMISAR imagery from the 1995 campaign over the Storstrommen Glacier in North East Greenland conducted by the Danish Center for Remote Sensing. This has...... reduced the baseline uncertainties from several meters to the centimeter level in a 36 km scene. Though developed for airborne SAR the method can easily be adopted to satellite data...

INSAR AND FINITE ELEMENT ANALYSIS OF GROUND DEFORMATION AT LAKE URMIA CAUSEWAY (LUC, NORTHWEST IRAN

Directory of Open Access Journals (Sweden)

R. Shamshiri

2013-09-01

Full Text Available Precise long-term deformation monitoring of causeways and bridges is of vital task for maintenance and management work related to transportation safety. In this study, we analyse the settlement of Lake Urmia Causeway (LUC, northwest Iran, using observations from InSAR and Finite Element Model (FEM simulation. For InSAR processing, we analyse 58 SAR images of ENVISAT, ALOS and TerraSAR-X (TSX using the SBAS technique to assess the settlement of embankments in the years 2003–2013. The InSAR results show deflation on both embankments with a peak velocity of > 5 cm/year in the satellite Line Of Sight (LOS direction. The InSAR observations are then used to construct a settlement compaction model for the cross section at the distance of 4 km from the most western edge of the causeway, using a 2D Finite Element Model. Our FEM results suggest that settlement of the embankments will continue in the future due to consolidation phenomenon.

There is no one-size-fits-all product for InSAR; on the inclusion of contextual information for geodetically-proof InSAR data products

Science.gov (United States)

Hanssen, R. F.

2017-12-01

In traditional geodesy, one is interested in determining the coordinates, or the change in coordinates, of predefined benchmarks. These benchmarks are clearly identifiable and are especially established to be representative of the signal of interest. This holds, e.g., for leveling benchmarks, for triangulation/trilateration benchmarks, and for GNSS benchmarks. The desired coordinates are not identical to the basic measurements, and need to be estimated using robust estimation procedures, where the stochastic nature of the measurements is taken into account. For InSAR, however, the `benchmarks' are not predefined. In fact, usually we do not know where an effective benchmark is located, even though we can determine its dynamic behavior pretty well. This poses several significant problems. First, we cannot describe the quality of the measurements, unless we already know the dynamic behavior of the benchmark. Second, if we don't know the quality of the measurements, we cannot compute the quality of the estimated parameters. Third, rather harsh assumptions need to be made to produce a result. These (usually implicit) assumptions differ between processing operators and the used software, and are severely affected by the amount of available data. Fourth, the `relative' nature of the final estimates is usually not explicitly stated, which is particularly problematic for non-expert users. Finally, whereas conventional geodesy applies rigorous testing to check for measurement or model errors, this is hardly ever done in InSAR-geodesy. These problems make it rather impossible to provide a precise, reliable, repeatable, and `universal' InSAR product or service. Here we evaluate the requirements and challenges to move towards InSAR as a geodetically-proof product. In particular this involves the explicit inclusion of contextual information, as well as InSAR procedures, standards and a technical protocol, supported by the International Association of Geodesy and the

Investigation of Slow-Moving Landslides from ALOS/PALSAR Images with TCPInSAR: A Case Study of Oso, USA

Directory of Open Access Journals (Sweden)

Qian Sun

2014-12-01

Full Text Available Monitoring slope instability is of great significance for understanding landslide kinematics and, therefore, reducing the related geological hazards. In recent years, interferometric synthetic aperture radar (InSAR has been widely applied to this end, especially thanks to the prompt evolution of multi-temporal InSAR (MTInSAR algorithms. In this paper, temporarily-coherent point InSAR (TCPInSAR, a recently-developed MTInSAR technique, is employed to investigate the slow-moving landslides in Oso, U.S., with 13 ALOS/PALSAR images. Compared to other MTInSAR techniques, TCPInSAR can work well with a small amount of data and is immune to unwrapping errors. Furthermore, the severe orbital ramps emanated from the inaccurate determination of the ALOS satellite’s state vector can be jointly estimated by TCPInSAR, resulting in an exhaustive separation between the orbital errors and displacement signals. The TCPInSAR-derived deformation map indicates that the riverside slopes adjacent to the North Fork of the Stillaguamish River, where the 2014 mudslide occurred, were active during 2007 and 2011. Besides, Coal Mountain has been found to be experiencing slow-moving landslides with clear boundaries and considerable magnitudes. The Deer Creek River is also threatened by a potential landslide dam due to the creeps detected in a nearby slope. The slope instability information revealed in this study is helpful to deal with the landslide hazards in Oso.

Source model for the Copahue volcano magmaplumbing system constrained by InSARsurface deformation observations

Science.gov (United States)

Lundgren, P.; Nikkhoo, M.; Samsonov, S. V.; Milillo, P.; Gil-Cruz, F., Sr.; Lazo, J.

2017-12-01

Copahue volcano straddling the edge of the Agrio-Caviahue caldera along the Chile-Argentinaborder in the southern Andes has been in unrest since inflation began in late 2011. We constrain Copahue'ssource models with satellite and airborne interferometric synthetic aperture radar (InSAR) deformationobservations. InSAR time series from descending track RADARSAT-2 and COSMO-SkyMed data span theentire inflation period from 2011 to 2016, with their initially high rates of 12 and 15 cm/yr, respectively,slowing only slightly despite ongoing small eruptions through 2016. InSAR ascending and descending tracktime series for the 2013-2016 time period constrain a two-source compound dislocation model, with a rate ofvolume increase of 13 × 106 m3/yr. They consist of a shallow, near-vertical, elongated source centered at2.5 km beneath the summit and a deeper, shallowly plunging source centered at 7 km depth connecting theshallow source to the deeper caldera. The deeper source is located directly beneath the volcano tectonicseismicity with the lower bounds of the seismicity parallel to the plunge of the deep source. InSAR time seriesalso show normal fault offsets on the NE flank Copahue faults. Coulomb stress change calculations forright-lateral strike slip (RLSS), thrust, and normal receiver faults show positive values in the north caldera forboth RLSS and normal faults, suggesting that northward trending seismicity and Copahue fault motion withinthe caldera are caused by the modeled sources. Together, the InSAR-constrained source model and theseismicity suggest a deep conduit or transfer zone where magma moves from the central caldera toCopahue's upper edifice.

Land subsidence and earth fissures in south-central and southern Arizona, USA

Science.gov (United States)

Conway, Brian D.

2016-05-01

Land subsidence due to groundwater overdraft has been an ongoing problem in south-central and southern Arizona (USA) since the 1940s. The first earth fissure attributed to excessive groundwater withdrawal was discovered in the early 1950s near Picacho. In some areas of the state, groundwater-level declines of more than 150 m have resulted in extensive land subsidence and earth fissuring. Land subsidence in excess of 5.7 m has been documented in both western metropolitan Phoenix and Eloy. The Arizona Department of Water Resources (ADWR) has been monitoring land subsidence since 2002 using interferometric synthetic aperture radar (InSAR) and since 1998 using a global navigation satellite system (GNSS). The ADWR InSAR program has identified more than 25 individual land subsidence features that cover an area of more than 7,300 km2. Using InSAR data in conjunction with groundwater-level datasets, ADWR is able to monitor land subsidence areas as well as identify areas that may require additional monitoring. One area of particular concern is the Willcox groundwater basin in southeastern Arizona, which is the focus of this paper. The area is experiencing rapid groundwater declines, as much as 32.1 m during 2005-2014 (the largest land subsidence rate in Arizona State—up to 12 cm/year), and a large number of earth fissures. The declining groundwater levels in Arizona are a challenge for both future groundwater availability and mitigating land subsidence associated with these declines. ADWR's InSAR program will continue to be a critical tool for monitoring land subsidence due to excessive groundwater withdrawal.

Integrating Remote Sensing Data, Hybrid-Cloud Computing, and Event Notifications for Advanced Rapid Imaging & Analysis (Invited)

Science.gov (United States)

Hua, H.; Owen, S. E.; Yun, S.; Lundgren, P.; Fielding, E. J.; Agram, P.; Manipon, G.; Stough, T. M.; Simons, M.; Rosen, P. A.; Wilson, B. D.; Poland, M. P.; Cervelli, P. F.; Cruz, J.

2013-12-01

Space-based geodetic measurement techniques such as Interferometric Synthetic Aperture Radar (InSAR) and Continuous Global Positioning System (CGPS) are now important elements in our toolset for monitoring earthquake-generating faults, volcanic eruptions, hurricane damage, landslides, reservoir subsidence, and other natural and man-made hazards. Geodetic imaging's unique ability to capture surface deformation with high spatial and temporal resolution has revolutionized both earthquake science and volcanology. Continuous monitoring of surface deformation and surface change before, during, and after natural hazards improves decision-making from better forecasts, increased situational awareness, and more informed recovery. However, analyses of InSAR and GPS data sets are currently handcrafted following events and are not generated rapidly and reliably enough for use in operational response to natural disasters. Additionally, the sheer data volumes needed to handle a continuous stream of InSAR data sets also presents a bottleneck. It has been estimated that continuous processing of InSAR coverage of California alone over 3-years would reach PB-scale data volumes. Our Advanced Rapid Imaging and Analysis for Monitoring Hazards (ARIA-MH) science data system enables both science and decision-making communities to monitor areas of interest with derived geodetic data products via seamless data preparation, processing, discovery, and access. We will present our findings on the use of hybrid-cloud computing to improve the timely processing and delivery of geodetic data products, integrating event notifications from USGS to improve the timely processing for response, as well as providing browse results for quick looks with other tools for integrative analysis.

Magmatic activity beneath the quiescent Three Sisters volcanic center, central Oregon Cascade Range, USA

Science.gov (United States)

Wicks, Charles W.; Dzurisin, Daniel; Ingebritsen, Steven; Thatcher, Wayne; Lu, Zhong; Iverson, Justin

2002-04-01

Images from satellite interferometric synthetic aperture radar (InSAR) reveal uplift of a broad ~10 km by 20 km area in the Three Sisters volcanic center of the central Oregon Cascade Range, ~130 km south of Mt. St. Helens. The last eruption in the volcanic center occurred ~1500 years ago. Multiple satellite images from 1992 through 2000 indicate that most if not all of ~100 mm of observed uplift occurred between September 1998 and October 2000. Geochemical (water chemistry) anomalies, first noted during 1990, coincide with the area of uplift and suggest the existence of a crustal magma reservoir prior to the uplift. We interpret the uplift as inflation caused by an ongoing episode of magma intrusion at a depth of ~6.5 km.

Coherent change detection and interferometric ISAR measurements in the folded compact range

Energy Technology Data Exchange (ETDEWEB)

Sorensen, K.W.

1996-08-01

A folded compact range configuration has been developed ant the Sandia National Laboratories` compact range antenna and radar-cross- section measurement facility as a means of performing indoor, environmentally-controlled, far-field simulations of synthetic aperture radar (SAR) measurements of distributed target samples (i.e. gravel, sand, etc.). The folded compact range configuration has previously been used to perform coherent-change-detection (CCD) measurements, which allow disturbances to distributed targets on the order of fractions of a wavelength to be detected. This report describes follow-on CCD measurements of other distributed target samples, and also investigates the sensitivity of the CCD measurement process to changes in the relative spatial location of the SAR sensor between observations of the target. Additionally, this report describes the theoretical and practical aspects of performing interferometric inverse-synthetic-aperture-radar (IFISAR) measurements in the folded compact range environment. IFISAR measurements provide resolution of the relative heights of targets with accuracies on the order of a wavelength. Several examples are given of digital height maps that have been generated from measurements performed at the folded compact range facility.

Activation of the SIGRIS monitoring system for ground deformation mapping during the Emilia 2012 seismic sequence, using COSMO-SkyMed InSAR data

Directory of Open Access Journals (Sweden)

Stefano Salvi

2012-10-01

Full Text Available On May 20, 2012, at 02:03 UTC, a moderate earthquake of local magnitude, Ml 5.9 started a seismic sequence in the central Po Plain of northern Italy The mainshock occurred in an area where seismicity of comparable magnitude has neither been recorded nor reported in the historical record over the last 1,000 years. The aftershock sequence evolved rapidly near the epicenter, with diminishing magnitudes until May 29, 2012, when at 07:00 UTC a large earthquake of Ml 5.8 occurred 12 km WSW of the mainshock, starting a new seismic sequence in the western area; a total of seven earthquakes with Ml >5 occurred in the area between May 20 and June 3, 2012. Immediately after the mainshock, the Italian Department of Civil Protection requested the Italian Space Agency to activate the Constellation of Small Satellites for Mediterranean Basin Observation (COSMO-SkyMed to provide Interferometric Synthetic Aperture Radar (InSAR coverage of the area. COSMO-SkyMed consists of four satellites in a 16-day repeat-pass cycle, with each carrying the same SAR payload. In the current orbital configuration, within each 16-day cycle, image pairs with temporal baselines of 1, 3, 4 and 8 days can be formed from the images acquired by the four different sensors. Combined with the availability of a wide range of electronically steered antenna beams with incidence angles ranging from about 16˚ to 50˚ at near-range, this capability allows trade-offs between temporal and spatial coverage to be exploited during acquisition planning. A joint team involving the Istituto Nazionale di Geofisica e Vulcanologia (INGV and the Istituto per il Rilevamento Elettromagnetico dell'Ambiente (IREA-CNR was activated to generate InSAR-based scientific products to support the emergency management. In this framework, the ASI and DPC requested that INGV activated the Space-based Monitoring System for Seismic Risk Management (SIGRIS. SIGRIS consists of a hardware/software infrastructure that is

SPECTROSCOPIC AND INTERFEROMETRIC MEASUREMENTS OF NINE K GIANT STARS

Energy Technology Data Exchange (ETDEWEB)

Baines, Ellyn K. [Remote Sensing Division, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Döllinger, Michaela P. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Guenther, Eike W.; Hatzes, Artie P. [Thüringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg (Germany); Hrudkovu, Marie [Isaac Newton Group of Telescopes, Apartado de Correos 321, E-387 00 Santa Cruz de la Palma, Canary Islands (Spain); Belle, Gerard T. van, E-mail: ellyn.baines@nrl.navy.mil [Lowell Observatory, Flagstaff, AZ 86001 (United States)

2016-09-01

We present spectroscopic and interferometric measurements for a sample of nine K giant stars. These targets are of particular interest because they are slated for stellar oscillation observations. Our improved parameters will directly translate into reduced errors in the final masses for these stars when interferometric radii and asteroseismic densities are combined. Here, we determine each star’s limb-darkened angular diameter, physical radius, luminosity, bolometric flux, effective temperature, surface gravity, metallicity, and mass. When we compare our interferometric and spectroscopic results, we find no systematic offsets in the diameters and the values generally agree within the errors. Our interferometric temperatures for seven of the nine stars are hotter than those determined from spectroscopy with an average difference of about 380 K.

InSAR Time Series Analysis of Natural and Anthropogenic Coastal Plain Subsidence: The Case of Sibari (Southern Italy

Directory of Open Access Journals (Sweden)

Giuseppe Cianflone

2015-11-01

Full Text Available We applied the Small Baseline Subset multi-temporal InSAR technique (SBAS to two SAR datasets acquired from 2003 up to 2013 by Envisat (ESA, European Space Agency and COSMO-SkyMed (ASI, Italian Space Agency satellites to investigate spatial and temporal patterns of land subsidence in the Sibari Plain (Southern Italy. Subsidence processes (up to ~20 mm/yr were investigated comparing geological, hydrogeological, and land use information with interferometric results. We suppose a correlation between subsidence and thickness of the Plio-Quaternary succession suggesting an active role of the isostatic compensation. Furthermore, the active back thrusting in the Corigliano Gulf could trigger a flexural subsidence mechanism even if fault activity and earthquakes do not seem play a role in the present subsidence. In this context, the compaction of Holocene deposits contributes to ground deformation. Despite the rapid urbanization of the area in the last 50 years, we do not consider the intensive groundwater pumping and related water table drop as the main triggering cause of subsidence phenomena, in disagreement with some previous publications. Our interpretation for the deformation fields related to natural and anthropogenic factors would be a comprehensive and exhaustive justification to the complexity of subsidence processes in the Sibari Plain.

Mapping Pyroclastic Flow Inundation Using Radar and Optical Satellite Images and Lahar Modeling

Directory of Open Access Journals (Sweden)

Chang-Wook Lee

2018-01-01

Full Text Available Sinabung volcano, located above the Sumatra subduction of the Indo-Australian plate under the Eurasian plate, became active in 2010 after about 400 years of quiescence. We use ALOS/PALSAR interferometric synthetic aperture radar (InSAR images to measure surface deformation from February 2007 to January 2011. We model the observed preeruption inflation and coeruption deflation using Mogi and prolate spheroid sources to infer volume changes of the magma chamber. We interpret that the inflation was due to magma accumulation in a shallow reservoir beneath Mount Sinabung and attribute the deflation due to magma withdrawal from the shallow reservoir during the eruption as well as thermoelastic compaction of erupted material. The pyroclastic flow extent during the eruption is then derived from the LAHARZ model based on the coeruption volume from InSAR modeling and compared to that derived from the Landsat 7 Enhanced Thematic Mapper Plus (ETM+ image. The pyroclastic flow inundation extents between the two different methods agree at about 86%, suggesting the capability of mapping pyroclastic flow inundation by combing radar and optical imagery as well as flow modeling.

Theory, analysis and design of RF interferometric sensors

CERN Document Server

Nguyen, Cam

2012-01-01

Theory, Analysis and Design of RF Interferometric Sensors presents the theory, analysis and design of RF interferometric sensors. RF interferometric sensors are attractive for various sensing applications that require every fine resolution and accuracy as well as fast speed. The book also presents two millimeter-wave interferometric sensors realized using RF integrated circuits. The developed millimeter-wave homodyne sensor shows sub-millimeter resolution in the order of 0.05 mm without correction for the non-linear phase response of the sensor's quadrature mixer. The designed millimeter-wave double-channel homodyne sensor provides a resolution of only 0.01 mm, or 1/840th of the operating wavelength, and can inherently suppress the non-linearity of the sensor's quadrature mixer. The experimental results of displacement and velocity measurement are presented as a way to demonstrate the sensing ability of the RF interferometry and to illustrate its many possible applications in sensing. The book is succinct, ye...

Improved synthetic-heterodyne Michelson interferometer vibrometer using phase and gain control feedback.

Science.gov (United States)

Galeti, José Henrique; Kitano, Cláudio; Connelly, Michael J

2015-12-10

Synthetic-heterodyne demodulation is a useful technique for dynamic displacement and velocity measurement using interferometric sensors as it can provide an output signal which is immune to interferometric drift. With the advent of cost effective, high-speed real-time signal processing systems and software, processing of the complex signals encountered in interferometry has become more feasible. In conventional synthetic-heterodyne demodulation schemes, to obtain the dynamic displacement or vibration of the object under test requires knowledge of the interferometer visibility and also the argument of two Bessel functions. In this paper, a new synthetic-heterodyne demodulation method is described leading to an expression for the dynamic displacement and velocity of the object under test that is significantly less sensitive to the received optical power. In addition, the application of two independent phase and gain feedback loops is used to compensate for the nonideal gain and phase response of the anti-aliasing filter required for the signal acquisition of the received wideband interferometer signal. The efficacy of the improved system is demonstrated by measuring the displacement sensitivity frequency response and linearity of a Piezoelectric Mirror-Shifter (PMS) over a range of 200 Hz-9 kHz. In addition, the system is used to measure the response of the PMS to triangular and impulse type stimuli. The experimental results show excellent agreement with measurements taken using two independent industry standard calibration methods.

Wide-Area Landslide Deformation Mapping with Multi-Path ALOS PALSAR Data Stacks: A Case Study of Three Gorges Area, China

Directory of Open Access Journals (Sweden)

Xuguo Shi

2016-02-01

Full Text Available In recent years, satellite synthetic aperture radar interferometry (InSAR has been adopted as a spaceborne geodetic tool to successfully measure surface deformation of a few well-known landslides in the Three Gorges area. In consideration of the fact that most events of slope failure happened at places other than those famous landslides since the reservoir impoundment in 2003, focusing on a limited number of slopes is insufficient to meet the requirements of regional-scale landslide disaster prevention and early warning. As a result, it has become a vital task to evaluate the overall stability of slopes across the vast area of Three Gorges using wide-coverage InSAR datasets. In this study, we explored the approach of carrying out joint analysis of multi-path InSAR data stacks for wide-area landslide deformation mapping. As an example, three ALOS (Advanced Land Observing Satellite PALSAR (Phased Array type L-band Synthetic Aperture Radar data stacks of neighboring ascending paths covering the area along the Yangtze River from Fengjie to Zigui were analyzed. A key problem to be solved is the separation of the tropospheric signal from the interferometric phase, for which we employed a hybrid description model of the atmospheric phase screen (APS to improve APS estimation from time series interferograms. The estimated atmospheric phase was largely correlated with the seasonal rainfall in the temporal dimension. The experimental results show that about 30 slopes covering total areas of 48 km2 were identified to be landslides in active deformation and should be kept under routine surveillance. Analyses of time series displacement measurements revealed that most landslides in the mountainous area far away from Yangtze River suffered from linear deformation, whereas landslides located on the river bank were destabilized predominantly by the influences of reservoir water level fluctuation and rainfall.

Interseismic Deformation along the Red River Fault from InSAR Measurements

Science.gov (United States)

Chen, J.; Li, Z.; Clarke, P. J.

2017-12-01

The Red River Fault (RRF) zone is a profound geological discontinuity separating South China from Indochina. Right lateral movements along this >900 km fault are considered to accommodate the extrusion of SE China. Crustal deformation monitoring at high resolution is the key to understand the present-day mode of deformation in this zone and its interaction with the adjacent regions. This is the first study to measure the interseismic deformation of the entire fault with ALOS-1/2 and Sentinel-1 observations. Nine ascending tracks of ALOS-1 data between 2007 and 2011 are collected from the Alaska Satellite Facility (ASF), four descending tracks of Sentinel-1 data are acquired every 24 days since October 2014, and ALOS-2 data are being systematically acquired since 2014. The long wavelength (L-band) of ALOS-1/2 and short temporal baseline of Sentinel-1 ensure good coherence to overcome the limitations of heavy vegetation and variable climate in the region. Stacks of interferograms are generated by our automatic processing chain based on the InSAR Scientific Computing Environment (ISCE) software, ionospheric errors are estimated and corrected using the split-spectrum method (Fattahi et al., IEEE Trans. Geosci. Remote Sens., 2017) and the tropospheric delays are calibrated using the Generic Atmospheric Correction Online Service for InSAR (GACOS: http://ceg-research.ncl.ac.uk/v2/gacos) with high-resolution ECMWF products (Yu et al., J. Geophys. Res., 2017). Time series analysis is performed to determine the interseismic deformation rate of the RRF using the in-house InSAR time series with atmospheric estimation model (InSAR TS + AEM) package based on the Small Baseline Subset (SBAS) algorithm. Our results reveal the decrease of slip rate from north to south. We map the interseismic strain rate field to characterize the deformation patterns and seismic hazard throughout the RRF zone.

Preliminary Study of Ground Movement in Prone Landslide Area by Means of MAI InSAR A Case Study: Ciloto, West Java, Indonesia

Science.gov (United States)

Hayati, Noorlaila; Riedel, Björn; Niemeier, Wolfgang

2016-04-01

Ciloto is one of the most prone landslide hazard areas in Indonesia. Several landslides in 2012 and 2013 had been recorded in Ciloto and damaged infrastructure around the area. Investigating the history of ground movement along slope area before the landslide happened could support the hazard mitigation in the future. Considering to an efficient surveying method, space-borne SAR processing is the one appropriate way to monitor the phenomenon in past years. The purpose of this study is detecting ground movement using multi-temporal synthetic aperture radar images. We use 13 ALOS PALSAR images from 2007 to 2009 with combination Fine Beam Single (FBS) and Fine Beam Double (FBD) polarization to investigate the slow movement on slope topography. MAI (Multiple Aperture Interferometry) InSAR method is used to analyze the ground movement from both line-of-sight and along-track direction. We split the synthetic aperture into two-looking aperture so that along-track displacement could be created by the difference of forward-backward looking interferograms. With integration of both methods, we could more precisely detect the movement in prone landslide area and achieve two measurements produced by the same interferogram. However, InSAR requires smaller baseline and good temporal baseline between master and slave images to avoid decorellation. There are only several pairs that meet the condition of proper length and temporal baseline indeed the location is also on the agriculture area where is mostly covered by vegetation. The result for two years observation shows that there is insignificant slow movement along slope surface in Ciloto with -2 - -7 cm in range looks or line of sight and 9-40 cm in along track direction. Based on geometry SAR , the most visible detecting of displacement is on the north-west area due to utilization of ascending SAR images.

Three-dimensional coastal geomorphology deformation modelling using differential synthetic aperture interferometry

Energy Technology Data Exchange (ETDEWEB)

Marghany, Maged [Universiti Teknologi Malaysia, Skudai, Johor Bahru (Malaysia). Inst. for Science and Technology Geospatial (INSTeG)

2012-06-15

This work presents a new approach for three-dimensional (3D) coastal deformation simulation using differential synthetic aperture interferometry (DInSAR). In doing so, conventional InSAR procedures are implemented to three repeat passes of RADARSAT-1 SAR fine mode data (F1). Further, the DInSAR method is implemented with the phase unwrapping technique. Consequently, DInSAR is used to eliminate the phase decorrelation impact from the interferograms. The study shows the accurate performance of DInSAR with a root mean square error of 0.02 {+-} 0.21 m and 90% confidence intervals. In conclusion, the DInSAR technique produces an accurate 3D coastal geomorphology reconstruction. (orig.)

The linearized inversion of the generalized interferometric multiple imaging

KAUST Repository

Aldawood, Ali

2016-09-06

The generalized interferometric multiple imaging (GIMI) procedure can be used to image duplex waves and other higher order internal multiples. Imaging duplex waves could help illuminate subsurface zones that are not easily illuminated by primaries such as vertical and nearly vertical fault planes, and salt flanks. To image first-order internal multiple, the GIMI framework consists of three datuming steps, followed by applying the zero-lag cross-correlation imaging condition. However, the standard GIMI procedure yields migrated images that suffer from low spatial resolution, migration artifacts, and cross-talk noise. To alleviate these problems, we propose a least-squares GIMI framework in which we formulate the first two steps as a linearized inversion problem when imaging first-order internal multiples. Tests on synthetic datasets demonstrate the ability to localize subsurface scatterers in their true positions, and delineate a vertical fault plane using the proposed method. We, also, demonstrate the robustness of the proposed framework when imaging the scatterers or the vertical fault plane with erroneous migration velocities.

The 2007-8 volcanic eruption on Jebel at Tair island (Red Sea) observed by satellite radar and optical images

KAUST Repository

Xu, Wenbin; Jonsson, Sigurjon

2014-01-01

We use high-resolution optical images and Interferometric Synthetic Aperture Radar (InSAR) data to study the September 2007-January 2008 Jebel at Tair eruption. Comparison of pre- and post-eruption optical images reveals several fresh ground fissures, a new scoria cone near the summit, and that 5.9 ± 0.1 km2 of new lava covered about half of the island. Decorrelation in the InSAR images indicates that lava flowed both to the western and to the northeastern part of the island after the start of the eruption, while later lavas were mainly deposited near the summit and onto the north flank of the volcano. From the InSAR data, we also estimate that the average thickness of the lava flows is 3.8 m, resulting in a bulk volume of around 2.2 × 107 m3. We observe no volcano-wide pre- or post-eruption uplift, which suggests that the magma source may be deep. The co-eruption interferograms, on the other hand, reveal local and rather complex deformation. We use these observations to constrain a tensile dislocation model that represents the dike intrusion that fed the eruption. The model results show that the orientation of the dike is perpendicular to the Red Sea rift, implying that the local stresses within the volcanic edifice are decoupled from the regional stress field. © 2014 Springer-Verlag Berlin Heidelberg.

The 2007-8 volcanic eruption on Jebel at Tair island (Red Sea) observed by satellite radar and optical images

KAUST Repository

Xu, Wenbin

2014-01-31

We use high-resolution optical images and Interferometric Synthetic Aperture Radar (InSAR) data to study the September 2007-January 2008 Jebel at Tair eruption. Comparison of pre- and post-eruption optical images reveals several fresh ground fissures, a new scoria cone near the summit, and that 5.9 ± 0.1 km2 of new lava covered about half of the island. Decorrelation in the InSAR images indicates that lava flowed both to the western and to the northeastern part of the island after the start of the eruption, while later lavas were mainly deposited near the summit and onto the north flank of the volcano. From the InSAR data, we also estimate that the average thickness of the lava flows is 3.8 m, resulting in a bulk volume of around 2.2 × 107 m3. We observe no volcano-wide pre- or post-eruption uplift, which suggests that the magma source may be deep. The co-eruption interferograms, on the other hand, reveal local and rather complex deformation. We use these observations to constrain a tensile dislocation model that represents the dike intrusion that fed the eruption. The model results show that the orientation of the dike is perpendicular to the Red Sea rift, implying that the local stresses within the volcanic edifice are decoupled from the regional stress field. © 2014 Springer-Verlag Berlin Heidelberg.

Determining Volcanic Deformation at San Miguel Volcano, El Salvador by Integrating Radar Interferometry and Seismic Analyses

Science.gov (United States)

Schiek, C. G.; Hurtado, J. M.; Velasco, A. A.; Buckley, S. M.; Escobar, D.

2008-12-01

From the early 1900's to the present day, San Miguel volcano has experienced many small eruptions and several periods of heightened seismic activity, making it one of the most active volcanoes in the El Salvadoran volcanic chain. Prior to 1969, the volcano experienced many explosive eruptions with Volcano Explosivity Indices (VEI) of 2. Since then, eruptions have decreased in intensity to an average VEI of 1. Eruptions mostly consist of phreatic explosions and central vent eruptions. Due to the explosive nature of this volcano, it is important to study the origins of the volcanism and its relationship to surface deformation and earthquake activity. We analyze these interactions by integrating interferometric synthetic aperture radar (InSAR) results with earthquake source location data from a ten-month (March 2007-January 2008) seismic deployment. The InSAR results show a maximum of 7 cm of volcanic inflation from March 2007 to mid-October 2007. During this time, seismic activity increased to a Real-time Seismic-Amplitude Measurement (RSAM) value of >400. Normal RSAM values for this volcano are earthquakes that occurred between March 2007 and January 2008 suggests a fault zone through the center of the San Miguel volcanic cone. This fault zone is most likely where dyke propagation is occurring. Source mechanisms will be determined for the earthquakes associated with this fault zone, and they will be compared to the InSAR deformation field to determine if the mid-October seismic activity and observed surface deformation are compatible.

Time-delay interferometric ranging for space-borne gravitational-wave detectors

International Nuclear Information System (INIS)

Tinto, Massimo; Vallisneri, Michele; Armstrong, J.W.

2005-01-01

Space-borne interferometric gravitational-wave detectors, sensitive in the low-frequency (mHz) band, will fly in the next decade. In these detectors, the spacecraft-to-spacecraft light-travel times will necessarily be unequal and time varying, and (because of aberration) will have different values on up- and down-links. In such unequal-armlength interferometers, laser-phase noise will be canceled by taking linear combinations of the laser-phase observables measured between pairs of spacecraft, appropriately time shifted by the light propagation times along the corresponding arms. This procedure, known as time-delay interferometry (TDI), requires an accurate knowledge of the light-time delays as functions of time. Here we propose a high-accuracy technique to estimate these time delays, and we study its use in the context of the Laser Interferometer Space Antenna (LISA) mission. We refer to this ranging technique, which relies on the TDI combinations themselves, as time-delay interferometric ranging (TDIR). For every TDI combination, we show that, by minimizing the rms power in that combination (averaged over integration times ∼10 4 s) with respect to the time-delay parameters, we obtain estimates of the time delays accurate enough to cancel laser noise to a level well below the secondary noises. Thus TDIR allows the implementation of TDI without the use of dedicated interspacecraft ranging systems, with a potential simplification of the LISA design. In this paper we define the TDIR procedure formally, and we characterize its expected performance via simulations with the Synthetic LISA software package

PIXEL: Japanese InSAR community for crustal deformation research

Science.gov (United States)

Furuya, M.; Shimada, M.; Ozawa, T.; Fukushima, Y.; Aoki, Y.; Miyagi, Y.; Kitagawa, S.

2007-12-01

In anticipation of the launch of ALOS (Advanced Land Observation Satellite) by JAXA (Japan Aerospace eXploration Agency), and in order to expand and bolster the InSAR community for crustal deformation research in Japan, a couple of scientists established a consortium, PIXEL, in November 2005 in a completely bottom-up fashion. PIXEL stands for Palsar Interferometry Consortium to Study our Evolving Land. Formally, it is a research contract between JAXA and Earthquake Research Institute (ERI), University of Tokyo. As ERI is a shared institute of the Japanese universities and research institutes, every scientist at all Japanese universities and institutes can participate in this consortium. The activity of PIXEL includes information exchange by mailing list, tutorial workshop for InSAR software, research workshop, and PALSAR data sharing. After the launch of ALOS, we have already witnessed several earthquakes and volcanic activities using PALSAR interferometry. We will briefly show and digest some of those observation results.

Measurement and imaging of infragravity waves in sea ice using InSAR

Science.gov (United States)

Mahoney, Andrew R.; Dammann, Dyre O.; Johnson, Mark A.; Eicken, Hajo; Meyer, Franz J.

2016-06-01

Using short-temporal baseline interferometric synthetic aperture radar, we capture instantaneous images of a persistent field of infragravity waves propagating through sea ice near Barrow, Alaska, during January 2015. We estimate wave amplitudes to be between 1.2 and 1.8 mm. Curvature of wavefronts is consistent with refraction of waves entering shallow water from a source region north of Barrow. A shallow water wave model indicates that the geometry of the wavefronts is relatively insensitive to the source location, but other evidence suggests the waves may have originated in the North Atlantic, making this perhaps the longest observed propagation path for waves through ice. We also note that steepening of the waves entering shallow water can increase the peak strain by an order of magnitude, suggesting that infragravity waves may play a role in determining the location of the landfast ice edge with respect to water depth.

Super-virtual Interferometric Separation and Enhancement of Back-scattered Surface Waves

KAUST Repository

Guo, Bowen

2015-08-19

Back-scattered surface waves can be migrated to detect near-surface reflectors with steep dips. A robust surface-wave migration requires the prior separation of the back-scattered surface-wave events from the data. This separation is often difficult to implement because the back-scattered surface waves are masked by the incident surface waves. We mitigate this problem by using a super-virtual interferometric method to enhance and separate the back-scattered surface waves. The key idea is to calculate the virtual back-scattered surface waves by stacking the resulting virtual correlated and convolved traces associated with the incident and back-scattered waves. Stacking the virtual back-scattered surface waves improves their signal-to-noise ratio and separates the back-scattered surface-waves from the incident field. Both synthetic and field data results validate the robustness of this method.

Change Detection by Interferometric Coherence in Nasca Lines, Peru (1997-2004)

Science.gov (United States)

Ruescas, Ana B.; Delgado, J. Manuel; Costantini, Fabiano; Sarti, Francesco

2010-03-01

Two interferometric pairs of Synthetic Aperture Radar (SAR) images are used to generate coherence images of the Nasca Lines Pampa area. The first coherence image is based on a pair of ERS-2 SAR data from 1997 and 1999; the second one is computed from two ENVISAT-ASAR (Advanced SAR) images from 2003 and 2004. The main objective is to study the changes in the coherence values in different parts of the area. Several different decorrelation factors contributing to a loss of coherency in a radar pair can be distinguished, and these include the temporal change in the ground properties and nature between the two satellite passes. In order to do this discrimination and interpretation, some ancillary data can be used, such as optical data from the Advanced Land Observing Satellite (ALOS), and meteorological data from the Global Precipitation Climatology Center (GPCC).

Modified interferometric imaging condition for reverse-time migration

Science.gov (United States)

Guo, Xue-Bao; Liu, Hong; Shi, Ying

2018-01-01

For reverse-time migration, high-resolution imaging mainly depends on the accuracy of the velocity model and the imaging condition. In practice, however, the small-scale components of the velocity model cannot be estimated by tomographical methods; therefore, the wavefields are not accurately reconstructed from the background velocity, and the imaging process will generate artefacts. Some of the noise is due to cross-correlation of unrelated seismic events. Interferometric imaging condition suppresses imaging noise very effectively, especially the unknown random disturbance of the small-scale part. The conventional interferometric imaging condition is extended in this study to obtain a new imaging condition based on the pseudo-Wigner distribution function (WDF). Numerical examples show that the modified interferometric imaging condition improves imaging precision.

InSAR to support sustainable urbanization over compacting aquifers: The case of Toluca Valley, Mexico

Science.gov (United States)

Castellazzi, Pascal; Garfias, Jaime; Martel, Richard; Brouard, Charles; Rivera, Alfonso

2017-12-01

This paper illustrates how InSAR alone can be used to delineate potential ground fractures related to aquifer system compaction. An InSAR-derived ground fracturing map of the Toluca Valley, Mexico, is produced and validated through a field campaign. The results are of great interest to support sustainable urbanization and show that InSAR processing of open-access Synthetic Aperture Radar (SAR) data from the Sentinel-1 satellites can lead to reliable and cost-effective products directly usable by cities to help decision-making. The Toluca Valley Aquifer (TVA) sustains the water needs of two million inhabitants living within the valley, a growing industry, an intensively irrigated agricultural area, and 38% of the water needs of the megalopolis of Mexico City, located 40 km east of the valley. Ensuring water sustainability, infrastructure integrity, along with supporting the important economic and demographic growth of the region, is a major challenge for water managers and urban developers. This paper presents a long-term analysis of ground fracturing by interpreting 13 years of InSAR-derived ground displacement measurements. Small Baseline Subset (SBAS) and Persistent Scatterer Interferometry (PSI) techniques are applied over three SAR datasets totalling 93 acquisitions from Envisat, Radarsat-2, and Sentinel-1A satellites and covering the period from 2003 to 2016. From 2003 to 2016, groundwater level declines of up to 1.6 m/yr, land subsidence up to 77 mm/yr, and major infrastructure damages are observed. Groundwater level data show highly variable seasonal responses according to their connectivity to recharge areas. However, the trend of groundwater levels consistently range from -0.5 to -1.5 m/yr regardless of the well location and depth. By analysing the horizontal gradients of vertical land subsidence, we provide a potential ground fracture map to assist in future urban development planning in the Toluca Valley.

Pre-2014 mudslides at Oso revealed by InSAR and multi-source DEM analysis

Science.gov (United States)

Kim, J. W.; Lu, Z.; QU, F.

2014-12-01

The landslide is a process that results in the downward and outward movement of slope-reshaping materials including rocks and soils and annually causes the loss of approximately $3.5 billion and tens of casualties in the United States. The 2014 Oso mudslide was an extreme event costing nearly 40 deaths and damaging civilian properties. Landslides are often unpredictable, but in many cases, catastrophic events are repetitive. Historic record in the Oso mudslide site indicates that there have been serial events in decades, though the extent of sliding events varied from time to time. In our study, the combination of multi-source DEMs, InSAR, and time-series InSAR analysis has enabled to characterize the Oso mudslide. InSAR results from ALOS PALSAR show that there was no significant deformation between mid-2006 and 2011. The combination of time-series InSAR analysis and old-dated DEM indicated revealed topographic changes associated the 2006 sliding event, which is confirmed by the difference of multiple LiDAR DEMs. Precipitation and discharge measurements before the 2006 and 2014 landslide events did not exhibit extremely anomalous records, suggesting the precipitation is not the controlling factor in determining the sliding events at Oso. The lack of surface deformation during 2006-2011 and weak correlation between the precipitation and the sliding event, suggest other factors (such as porosity) might play a critical role on the run-away events at this Oso and other similar landslides.

Ground subsidence and associated ground fracturing in urban areas: InSAR monitoring of active tectonic structures (Ciudad Guzman, Colima Graben - Mexico)

Science.gov (United States)

Bignami, C.; Brunori, C.; Zucca, F.; Groppelli, G.; Norini, G.; Hernandez, N. D.; Stramondo, S.

2013-12-01

This study focuses on the observation of a creeping phenomenon that produces subsidence of the Zapotlan basin and ground fracturing in correspondence of the Ciudad Guzmàn (Jalisco - Mexico). The September 21, 2012, the Ciudad Guzmàn has been struck by a phenomenon of ground fracturing of about 1.5 km of length. This event caused the deformation of the roads and the damage of 30 houses, of which eight have been declared uninhabitable. The alignment of fractures is coincident with the escarpments produced in September 19, 1985, in the Ciudad Guzman urban area, when a strong earthquake, magnitude 8.1, struck the Mexican area, causing the deaths of at least 10,000 people and serious damage in Mexico City. In Ciudad Guzmán, about 60% of the buildings were destroyed, with about 50 loss of life. The city is located in the Zapotlan basin (northern Colima graben), a wide tectonic depression where the depth of the infilling sediments is about 1 km. This subsidence cannot be measured outside the urbanized area, but it can be considered as a deformation mechanism of the central part of the basin. In order to detect and mapping the spatio-temporal features of the processes that led to this event, we applied InSAR multi-temporal techniques to analyze a dataset of ENVISAT satellite SAR images, acquired in a time span between 2003-2010. InSAR techniques detect a subsidence of the north-western part of Ciudad Guzmàn of about 15 mm/yr in the time interval 2003-2010. The displacement occurred in September 21, 2012, was detected using two RadarSAT2 acquisitions (2012-03-22 and 2013-03-17). The explanation of surface movements based on interferometric results, ground data and geological field observations, allowed confirming surface effect due to the overexploitation of the aquifers and highlights a subsidence due to anthropogenic causes coupled to buried tectonic structures.

Basin Scale Assessment of Landslides Geomorphological Setting by Advanced InSAR Analysis

Directory of Open Access Journals (Sweden)

Francesca Bozzano

2017-03-01

Full Text Available An extensive investigation of more than 90 landslides affecting a small river basin in Central Italy was performed by combining field surveys and remote sensing techniques. We thus defined the geomorphological setting of slope instability processes. Basic information, such as landslides mapping and landslides type definition, have been acquired thanks to geomorphological field investigations and multi-temporal aerial photos interpretation, while satellite SAR archive data (acquired by ERS and Envisat from 1992 to 2010 have been analyzed by means of A-DInSAR (Advanced Differential Interferometric Synthetic Aperture Radar techniques to evaluate landslides past displacements patterns. Multi-temporal assessment of landslides state of activity has been performed basing on geomorphological evidence criteria and past ground displacement measurements obtained by A-DInSAR. This step has been performed by means of an activity matrix derived from information achieved thanks to double orbital geometry. Thanks to this approach we also achieved more detailed knowledge about the landslides kinematics in time and space.

Computational adaptive optics for broadband optical interferometric tomography of biological tissue.

Science.gov (United States)

Adie, Steven G; Graf, Benedikt W; Ahmad, Adeel; Carney, P Scott; Boppart, Stephen A

2012-05-08

Aberrations in optical microscopy reduce image resolution and contrast, and can limit imaging depth when focusing into biological samples. Static correction of aberrations may be achieved through appropriate lens design, but this approach does not offer the flexibility of simultaneously correcting aberrations for all imaging depths, nor the adaptability to correct for sample-specific aberrations for high-quality tomographic optical imaging. Incorporation of adaptive optics (AO) methods have demonstrated considerable improvement in optical image contrast and resolution in noninterferometric microscopy techniques, as well as in optical coherence tomography. Here we present a method to correct aberrations in a tomogram rather than the beam of a broadband optical interferometry system. Based on Fourier optics principles, we correct aberrations of a virtual pupil using Zernike polynomials. When used in conjunction with the computed imaging method interferometric synthetic aperture microscopy, this computational AO enables object reconstruction (within the single scattering limit) with ideal focal-plane resolution at all depths. Tomographic reconstructions of tissue phantoms containing subresolution titanium-dioxide particles and of ex vivo rat lung tissue demonstrate aberration correction in datasets acquired with a highly astigmatic illumination beam. These results also demonstrate that imaging with an aberrated astigmatic beam provides the advantage of a more uniform depth-dependent signal compared to imaging with a standard gaussian beam. With further work, computational AO could enable the replacement of complicated and expensive optical hardware components with algorithms implemented on a standard desktop computer, making high-resolution 3D interferometric tomography accessible to a wider group of users and nonspecialists.

Unravelling InSAR observed Antarctic ice-shelf flexure using 2-D elastic and viscoelastic modelling

Science.gov (United States)

Wild, Christian T.; Marsh, Oliver J.; Rack, Wolfgang

2018-04-01

Ice-shelf grounding zones link the Antarctic ice-sheets to the ocean. Differential interferometric synthetic aperture radar (DInSAR) is commonly used to monitor grounding-line locations, but also contains information on grounding-zone ice thickness, ice properties and tidal conditions beneath the ice shelf. Here, we combine in-situ data with numerical modelling of ice-shelf flexure to investigate 2-D controls on the tidal bending pattern on the Southern McMurdo Ice Shelf. We validate our results with 9 double-differential TerraSAR-X interferograms. It is necessary to make adjustments to the tidal forcing to directly compare observations with model output and we find that when these adjustments are small (tide models are required to allow for the full exploitation of DInSAR in grounding-zone glaciology.

Accurate formulas for the penalty caused by interferometric crosstalk

DEFF Research Database (Denmark)

Rasmussen, Christian Jørgen; Liu, Fenghai; Jeppesen, Palle

2000-01-01

New simple formulas for the penalty caused by interferometric crosstalk in PIN receiver systems and optically preamplified receiver systems are presented. They are more accurate than existing formulas.......New simple formulas for the penalty caused by interferometric crosstalk in PIN receiver systems and optically preamplified receiver systems are presented. They are more accurate than existing formulas....

Anthropogenic and geologic influences on subsidence in the vicinity of New Orleans, Louisiana

Science.gov (United States)

Jones, Cathleen E.; An, Karen; Blom, Ronald G.; Kent, Joshua D.; Ivins, Erik R.; Bekaert, David

2016-05-01

New measurements of ongoing subsidence of land proximal to the city of New Orleans, Louisiana, and including areas around the communities of Norco and Lutcher upriver along the Mississippi are reported. The rates of vertical motion are derived from interferometric synthetic aperture radar (InSAR) applied to Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) data acquired on 16 June 2009 and 2 July 2012. The subsidence trends are similar to those reported for 2002-2004 in parts of New Orleans where observations overlap, in particular in Michoud, the 9th Ward, and Chalmette, but are measured at much higher spatial resolution (6 m). The spatial associations of cumulative surface movements suggest that the most likely drivers of subsidence are groundwater withdrawal and surficial drainage/dewatering activities. High subsidence rates are observed localized around some major industrial facilities and can affect nearby flood control infrastructure. Substantial subsidence is observed to occur rapidly from shallow compaction in highly localized areas, which is why it could be missed in subsidence surveys relying on point measurements at limited locations.

Which Fault Segments Ruptured in the 2008 Wenchuan Earthquake and Which Did Not? New Evidence from Near‐Fault 3D Surface Displacements Derived from SAR Image Offsets

KAUST Repository

Feng, Guangcai

2017-03-15

The 2008 Mw 7.9 Wenchuan earthquake ruptured a complex thrust‐faulting system at the eastern edge of the Tibetan plateau and west of Sichuan basin. Though the earthquake has been extensively studied, several details about the earthquake, such as which fault segments were activated in the earthquake, are still not clear. This is in part due to difficult field access to the fault zone and in part due to limited near‐fault observations in Interferometric Synthetic Aperture Radar (InSAR) observations because of decorrelation. In this study, we address this problem by estimating SAR image offsets that provide near‐fault ground displacement information and exhibit clear displacement discontinuities across activated fault segments. We begin by reanalyzing the coseismic InSAR observations of the earthquake and then mostly eliminate the strong ionospheric signals that were plaguing previous studies by using additional postevent images. We also estimate the SAR image offsets and use their results to retrieve the full 3D coseismic surface displacement field. The coseismic deformation from the InSAR and image‐offset measurements are compared with both Global Positioning System and field observations. The results indicate that our observations provide significantly better information than previous InSAR studies that were affected by ionospheric disturbances. We use the results to present details of the surface‐faulting offsets along the Beichuan fault from the southwest to the northeast and find that there is an obvious right‐lateral strike‐slip component (as well as thrust faulting) along the southern Beichuan fault (in Yingxiu County), which was strongly underestimated in earlier studies. Based on the results, we provide new evidence to show that the Qingchuan fault was not ruptured in the 2008 Wenchuan earthquake, a topic debated in field observation studies, but show instead that surface faulting occurred on a northward extension of the Beichuan fault during

Which Fault Segments Ruptured in the 2008 Wenchuan Earthquake and Which Did Not? New Evidence from Near‐Fault 3D Surface Displacements Derived from SAR Image Offsets

KAUST Repository

Feng, Guangcai; Jonsson, Sigurjon; Klinger, Yann

2017-01-01

The 2008 Mw 7.9 Wenchuan earthquake ruptured a complex thrust‐faulting system at the eastern edge of the Tibetan plateau and west of Sichuan basin. Though the earthquake has been extensively studied, several details about the earthquake, such as which fault segments were activated in the earthquake, are still not clear. This is in part due to difficult field access to the fault zone and in part due to limited near‐fault observations in Interferometric Synthetic Aperture Radar (InSAR) observations because of decorrelation. In this study, we address this problem by estimating SAR image offsets that provide near‐fault ground displacement information and exhibit clear displacement discontinuities across activated fault segments. We begin by reanalyzing the coseismic InSAR observations of the earthquake and then mostly eliminate the strong ionospheric signals that were plaguing previous studies by using additional postevent images. We also estimate the SAR image offsets and use their results to retrieve the full 3D coseismic surface displacement field. The coseismic deformation from the InSAR and image‐offset measurements are compared with both Global Positioning System and field observations. The results indicate that our observations provide significantly better information than previous InSAR studies that were affected by ionospheric disturbances. We use the results to present details of the surface‐faulting offsets along the Beichuan fault from the southwest to the northeast and find that there is an obvious right‐lateral strike‐slip component (as well as thrust faulting) along the southern Beichuan fault (in Yingxiu County), which was strongly underestimated in earlier studies. Based on the results, we provide new evidence to show that the Qingchuan fault was not ruptured in the 2008 Wenchuan earthquake, a topic debated in field observation studies, but show instead that surface faulting occurred on a northward extension of the Beichuan fault during

The Synthetic Aperture Radar Science Data Processing Foundry Concept for Earth Science

Science.gov (United States)

Rosen, P. A.; Hua, H.; Norton, C. D.; Little, M. M.

2015-12-01

Since 2008, NASA's Earth Science Technology Office and the Advanced Information Systems Technology Program have invested in two technology evolutions to meet the needs of the community of scientists exploiting the rapidly growing database of international synthetic aperture radar (SAR) data. JPL, working with the science community, has developed the InSAR Scientific Computing Environment (ISCE), a next-generation interferometric SAR processing system that is designed to be flexible and extensible. ISCE currently supports many international space borne data sets but has been primarily focused on geodetic science and applications. A second evolutionary path, the Advanced Rapid Imaging and Analysis (ARIA) science data system, uses ISCE as its core science data processing engine and produces automated science and response products, quality assessments and metadata. The success of this two-front effort has been demonstrated in NASA's ability to respond to recent events with useful disaster support. JPL has enabled high-volume and low latency data production by the re-use of the hybrid cloud computing science data system (HySDS) that runs ARIA, leveraging on-premise cloud computing assets that are able to burst onto the Amazon Web Services (AWS) services as needed. Beyond geodetic applications, needs have emerged to process large volumes of time-series SAR data collected for estimation of biomass and its change, in such campaigns as the upcoming AfriSAR field campaign. ESTO is funding JPL to extend the ISCE-ARIA model to a "SAR Science Data Processing Foundry" to on-ramp new data sources and to produce new science data products to meet the needs of science teams and, in general, science community members. An extension of the ISCE-ARIA model to support on-demand processing will permit PIs to leverage this Foundry to produce data products from accepted data sources when they need them. This paper will describe each of the elements of the SAR SDP Foundry and describe their

(abstract) Studies of Interferometric Penetration into Vegetation Canopies using Multifrequency Interferometry Data at JPL

Science.gov (United States)

Hensley, Scott; Rodriguez, Ernesto; Truhafft, Bob; van Zyl, Jakob; Rosen, Paul; Werner, Charles; Madsen, Sren; Chapin, Elaine

1997-01-01

Radar interferometric observations both from spaceborne and airborne platforms have been used to generate accurate topographic maps, measure milimeter level displacements from earthquakes and volcanoes, and for making land cover classification and land cover change maps. Interferometric observations have two basic measurements, interferometric phase, which depends upon the path difference between the two antennas and the correlation. One of the key questions concerning interferometric observations of vegetated regions is where in the canopy does the interferometric phase measure the height. Results for two methods of extracting tree heights and other vegetation parameters based upon the amount of volumetric decorrelation will be presented.

An Empirical Assessment of Temporal Decorrelation Using the Uninhabited Aerial Vehicle Synthetic Aperture Radar over Forested Landscapes

Directory of Open Access Journals (Sweden)

Michelle Hofton

2012-04-01

Full Text Available We present an empirical assessment of the impact of temporal decorrelation on interferometric coherence measured over a forested landscape. A series of repeat-pass interferometric radar images with a zero spatial baseline were collected with UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar, a fully polarimetric airborne L-band radar system. The dataset provided temporal separations of 45 minutes, 2, 7 and 9 days. Coincident airborne lidar and weather data were collected. We theoretically demonstrate that UAVSAR measurement accuracy enables accurate quantification of temporal decorrelation. Data analysis revealed precipitation events to be the main driver of temporal decorrelation over the acquisition period. The experiment also shows temporal decorrelation increases with canopy height, and this pattern was found consistent across forest types and polarization.

Plate boundary deformation and man-made subsidence around geothermal fields on the Reykjanes Peninsula, Iceland

KAUST Repository

Keiding, Marie; Á rnadó ttir, Thó ra; Jonsson, Sigurjon; Decriem, Judicaë l; Hooper, Andrew John

2010-01-01

We present Interferometric Synthetic Aperture Radar (InSAR) data from 1992-1999 and 2003-2008 as well as GPS data from 2000-2009 for the active plate boundary on the Reykjanes Peninsula, southwest Iceland. The geodetic data reveal deformation mainly due to plate spreading, anthropogenic subsidence caused by geothermal fluid extraction and, possibly, increasing pressure in a geothermal system. Subsidence of around 10. cm is observed during the first 2. years of production at the Reykjanes geothermal power plant, which started operating in May 2006. We model the surface subsidence around the new power plant using point and ellipsoidal pressure sources in an elastic halfspace. Short-lived swarms of micro-earthquakes as well as aseismic fault movement are observed near the geothermal field following the start of production, possibly triggered by the stresses induced by geothermal fluid extraction. © 2010 Elsevier B.V.

Plate boundary deformation and man-made subsidence around geothermal fields on the Reykjanes Peninsula, Iceland

KAUST Repository

Keiding, Marie

2010-07-01

We present Interferometric Synthetic Aperture Radar (InSAR) data from 1992-1999 and 2003-2008 as well as GPS data from 2000-2009 for the active plate boundary on the Reykjanes Peninsula, southwest Iceland. The geodetic data reveal deformation mainly due to plate spreading, anthropogenic subsidence caused by geothermal fluid extraction and, possibly, increasing pressure in a geothermal system. Subsidence of around 10. cm is observed during the first 2. years of production at the Reykjanes geothermal power plant, which started operating in May 2006. We model the surface subsidence around the new power plant using point and ellipsoidal pressure sources in an elastic halfspace. Short-lived swarms of micro-earthquakes as well as aseismic fault movement are observed near the geothermal field following the start of production, possibly triggered by the stresses induced by geothermal fluid extraction. © 2010 Elsevier B.V.

Improved SAR Image Coregistration Using Pixel-Offset Series

KAUST Repository

Wang, Teng

2014-03-14

Synthetic aperture radar (SAR) image coregistration is a key procedure before interferometric SAR (InSAR) time-series analysis can be started. However, many geophysical data sets suffer from severe decorrelation problems due to a variety of reasons, making precise coregistration a nontrivial task. Here, we present a new strategy that uses a pixel-offset series of detected subimage patches dominated by point-like targets (PTs) to improve SAR image coregistrations. First, all potentially coherent image pairs are coregistered in a conventional way. In this step, we propose a coregistration quality index for each image to rank its relative “significance” within the data set and to select a reference image for the SAR data set. Then, a pixel-offset series of detected PTs is made from amplitude maps to improve the geometrical mapping functions. Finally, all images are resampled depending on the pixel offsets calculated from the updated geometrical mapping functions. We used images from a rural region near the North Anatolian Fault in eastern Turkey to test the proposed method, and clear coregistration improvements were found based on amplitude stability. This enhanced the fact that the coregistration strategy should therefore lead to improved InSAR time-series analysis results.

Improved SAR Image Coregistration Using Pixel-Offset Series

KAUST Repository

Wang, Teng; Jonsson, Sigurjon; Hanssen, Ramon F.

2014-01-01

Synthetic aperture radar (SAR) image coregistration is a key procedure before interferometric SAR (InSAR) time-series analysis can be started. However, many geophysical data sets suffer from severe decorrelation problems due to a variety of reasons, making precise coregistration a nontrivial task. Here, we present a new strategy that uses a pixel-offset series of detected subimage patches dominated by point-like targets (PTs) to improve SAR image coregistrations. First, all potentially coherent image pairs are coregistered in a conventional way. In this step, we propose a coregistration quality index for each image to rank its relative “significance” within the data set and to select a reference image for the SAR data set. Then, a pixel-offset series of detected PTs is made from amplitude maps to improve the geometrical mapping functions. Finally, all images are resampled depending on the pixel offsets calculated from the updated geometrical mapping functions. We used images from a rural region near the North Anatolian Fault in eastern Turkey to test the proposed method, and clear coregistration improvements were found based on amplitude stability. This enhanced the fact that the coregistration strategy should therefore lead to improved InSAR time-series analysis results.

URBAN MODELLING PERFORMANCE OF NEXT GENERATION SAR MISSIONS

Directory of Open Access Journals (Sweden)

U. G. Sefercik

2017-09-01

Full Text Available In synthetic aperture radar (SAR technology, urban mapping and modelling have become possible with revolutionary missions TerraSAR-X (TSX and Cosmo-SkyMed (CSK since 2007. These satellites offer 1m spatial resolution in high-resolution spotlight imaging mode and capable for high quality digital surface model (DSM acquisition for urban areas utilizing interferometric SAR (InSAR technology. With the advantage of independent generation from seasonal weather conditions, TSX and CSK DSMs are much in demand by scientific users. The performance of SAR DSMs is influenced by the distortions such as layover, foreshortening, shadow and double-bounce depend up on imaging geometry. In this study, the potential of DSMs derived from convenient 1m high-resolution spotlight (HS InSAR pairs of CSK and TSX is validated by model-to-model absolute and relative accuracy estimations in an urban area. For the verification, an airborne laser scanning (ALS DSM of the study area was used as the reference model. Results demonstrated that TSX and CSK urban DSMs are compatible in open, built-up and forest land forms with the absolute accuracy of 8–10 m. The relative accuracies based on the coherence of neighbouring pixels are superior to absolute accuracies both for CSK and TSX.

Satellite radar interferometry for monitoring and early-stage warning of structural instability in archaeological sites

International Nuclear Information System (INIS)

Tapete, D; Fanti, R; Casagli, N; Cecchi, R; Petrangeli, P

2012-01-01

Satellite interferometric synthetic aperture radar (InSAR) monitoring campaigns were performed on the archaeological heritage of the Roman Forum, Palatino and Oppio Hills in the centre of Rome, Italy, to test the capabilities of persistent scatterer interferometry techniques for the preventive diagnosis of deformation threatening the structural stability of archaeological monuments and buried structures. ERS-1/2 and RADARSAT-1/2 SAR images were processed with the permanent scatterers InSAR (PSInSAR) and SqueeSAR approaches, and the identified measurement points (MP) were radar-interpreted to map the conservation criticalities in relation to the local geohazard factors and active deterioration processes. The multi-temporal reconstruction of past/recent instability events based on the MP deformation time series provided evidences of stabilization for the Domus Tiberiana as a consequence of recent restoration works, as well as of persistent deformation for the Temple of Magna Mater on the Palatino Hill and the structures of the Baths of Trajan on the Oppio Hill. Detailed time series analysis was also exploited to back monitor and understand the nature of the 2010 collapse that occurred close to Nero's Golden House, and to establish an early-stage warning procedure useful to preventively detect potential instability. (paper)

Performance Analysis for Airborne Interferometric SAR Affected by Flexible Baseline Oscillation

Directory of Open Access Journals (Sweden)

Liu Zhong-sheng

2014-04-01

Full Text Available The airborne interferometric SAR platform suffers from instability factors, such as air turbulence and mechanical vibrations during flight. Such factors cause the oscillation of the flexible baseline, which leads to significant degradation of the performance of the interferometric SAR system. This study is concerned with the baseline oscillation. First, the error of the slant range model under baseline oscillation conditions is formulated. Then, the SAR complex image signal and dual-channel correlation coefficient are modeled based on the first-order, second-order, and generic slant range error. Subsequently, the impact of the baseline oscillation on the imaging and interferometric performance of the SAR system is analyzed. Finally, simulations of the echo data are used to validate the theoretical analysis of the baseline oscillation in the airborne interferometric SAR.

Global Compilation of InSAR Earthquake Source Models: Comparisons with Seismic Catalogues and the Effects of 3D Earth Structure

Science.gov (United States)

Weston, J. M.; Ferreira, A. M.; Funning, G. J.

2010-12-01

While past progress in seismology led to extensive earthquake catalogues such as the Global Centroid Moment Tensor (GCMT) catalogue, recent advances in space geodesy have enabled earthquake parameter estimations from the measurement of the deformation of the Earth’s surface, notably using InSAR data. Many earthquakes have now been studied using InSAR, but a full assessment of the quality and of the additional value of these source parameters compared to traditional seismological techniques is still lacking. In this study we present results of systematic comparisons between earthquake CMT parameters determined using InSAR and seismic data, on a global scale. We compiled a large database of source parameters obtained using InSAR data from the literature and estimated the corresponding CMT parameters into a ICMT compilation. We here present results from the analysis of 58 earthquakes that occurred between 1992-2007 from about 80 published InSAR studies. Multiple studies of the same earthquake are included in the archive, as they are valuable to assess uncertainties. Where faults are segmented, with changes in width along-strike, a weighted average based on the seismic moment in each fault has been used to determine overall earthquake parameters. For variable slip models, we have calculated source parameters taking the spatial distribution of slip into account. The parameters in our ICMT compilation are compared with those taken from the Global CMT (GCMT), ISC, EHB and NEIC catalogues. We find that earthquake fault strike, dip and rake values in the GCMT and ICMT archives are generally compatible with each other. Likewise, the differences in seismic moment in these two archives are relatively small. However, the locations of the centroid epicentres show substantial discrepancies, which are larger when comparing with GCMT locations (10-30km differences) than for EHB, ISC and NEIC locations (5-15km differences). Since InSAR data have a high spatial resolution, and thus

Physics-Based Predictions for Coherent Change Detection Using X-Band Synthetic Aperture Radar

Directory of Open Access Journals (Sweden)

Mark Preiss

2005-12-01

Full Text Available A theoretical model is developed to describe the interferometric coherency between pairs of SAR images of rough soil surfaces. The model is derived using a dyadic form for surface reflectivity in the Kirchhoff approximation. This permits the combination of Kirchhoff theory and spotlight synthetic aperture radar (SAR image formation theory. The resulting model is used to describe the interferometric coherency between pairs of SAR images of rough soil surfaces. The theoretical model is applied to SAR images formed before and after surface changes observed by a repeat-pass SAR system. The change in surface associated with a tyre track following vehicle passage is modelled and SAR coherency estimates are obtained. Predicted coherency distributions for both the change and no-change scenarios are used to estimate receiver operator curves for the detection of the changes using a high-resolution, X-band SAR system.

ARIA: Delivering state-of-the-art InSAR products to end users

Science.gov (United States)

Agram, P. S.; Owen, S. E.; Hua, H.; Manipon, G.; Sacco, G. F.; Bue, B. D.; Fielding, E. J.; Yun, S. H.; Simons, M.; Webb, F.; Rosen, P. A.; Lundgren, P.; Liu, Z.

2016-12-01

Advanced Rapid Imaging and Analysis (ARIA) Center for Natural Hazards aims to bring state-of-the-art geodetic imaging capabilities to an operational level in support of local, national, and international hazard response communities. ARIA project's first foray into operational generation of InSAR products was with Calimap Project, in collaboration with ASI-CIDOT, using X-band data from the Cosmo-SkyMed constellation. Over the last year, ARIA's processing infrastructure has been significantly upgraded to exploit the free stream of high quality C-band SAR data from ESA's Sentinel-1 mission and related algorithmic improvements to the ISCE software. ARIA's data system can now operationally generate geocoded unwrapped phase and coherence products in GIS-friendly formats from Sentinel-1 TOPS mode data in an automated fashion, and this capability is currently being exercised various study sites across the United States including Hawaii, Central California, Iceland and South America. The ARIA team, building on the experience gained from handling X-band data and C-band data, has also built an automated machine learning-based classifier to label the auto-generated interferograms based on phase unwrapping quality. These high quality "time-series ready" InSAR products generated using state-of-the-art processing algorithms can be accessed by end users using two different mechanisms - 1) a Faceted-search interface that includes browse imagery for quick visualization and 2) an ElasticSearch-based API to enable bulk automated download, post-processing and time-series analysis. In this talk, we will present InSAR results from various global events that ARIA system has responded to. We will also discuss the set of geospatial big data tools including GIS libraries and API tools, that end users will need to familiarize themselves with in order to maximize the utilization of continuous stream of InSAR products from the Sentinel-1 and NISAR missions that the ARIA project will generate.

Leveraging Subsidence in Permafrost with Remotely Sensed Active Layer Thickness (ReSALT) Products

Science.gov (United States)

Schaefer, K. M.; Chen, A.; Chen, J.; Chen, R. H.; Liu, L.; Michaelides, R. J.; Moghaddam, M.; Parsekian, A.; Tabatabaeenejad, A.; Thompson, J. A.; Zebker, H. A.; Meyer, F. J.

2017-12-01

The Remotely Sensed Active Layer Thickness (ReSALT) product uses the Interferometric Synthetic Aperture Radar (InSAR) technique to measure ground subsidence in permafrost regions. Seasonal subsidence results from the expansion of soil water into ice as the surface soil or active layer freezes and thaws each year. Subsidence trends result from large-scale thaw of permafrost and from the melting and subsequent drainage of excess ground ice in permafrost-affected soils. The attached figure shows the 2006-2010 average seasonal subsidence from ReSALT around Barrow, Alaska. The average active layer thickness (the maximum surface thaw depth during summer) is 30-40 cm, resulting in an average seasonal subsidence of 1-3 cm. Analysis of the seasonal subsidence and subsidence trends provides valuable insights into important permafrost processes, such as the freeze/thaw of the active layer, large-scale thawing due to climate change, the impact of fire, and infrastructure vulnerability. ReSALT supports the Arctic-Boreal Vulnerability Experiment (ABoVE) field campaign in Alaska and northwest Canada and is a precursor for a potential NASA-ISRO Synthetic Aperture Radar (NISAR) product. ReSALT includes uncertainties for all parameters and is validated against in situ measurements from the Circumpolar Active Layer Monitoring (CALM) network, Ground Penetrating Radar and mechanical probe measurements. Here we present examples of ReSALT products in Alaska to highlight the untapped potential of the InSAR technique to understand permafrost dynamics, with a strong emphasis on the underlying processes that drive the subsidence.

Interferometric detection of single gold nanoparticles calibrated against TEM size distributions

DEFF Research Database (Denmark)

Zhang, Lixue; Christensen, Sune; Bendix, Pól Martin

2015-01-01

Single nanoparticle analysis: An interferometric optical approach calibrates sizes of gold nanoparticles (AuNPs) from the interference intensities by calibrating their interferometric signals against the corresponding transmission electron microscopy measurements. This method is used to investigate...

Seasonal thaw settlement at drained thermokarst lake basins, Arctic Alaska

Science.gov (United States)

Liu, Lin; Schaefer, Kevin; Gusmeroli, Alessio; Grosse, Guido; Jones, Benjamin M.; Zhang, Tinjun; Parsekian, Andrew; Zebker, Howard

2014-01-01

Drained thermokarst lake basins (DTLBs) are ubiquitous landforms on Arctic tundra lowland. Their dynamic states are seldom investigated, despite their importance for landscape stability, hydrology, nutrient fluxes, and carbon cycling. Here we report results based on high-resolution Interferometric Synthetic Aperture Radar (InSAR) measurements using space-borne data for a study area located on the North Slope of Alaska near Prudhoe Bay, where we focus on the seasonal thaw settlement within DTLBs, averaged between 2006 and 2010. The majority (14) of the 18 DTLBs in the study area exhibited seasonal thaw settlement of 3–4 cm. However, four of the DTLBs examined exceeded 4 cm of thaw settlement, with one basin experiencing up to 12 cm. Combining the InSAR observations with the in situ active layer thickness measured using ground penetrating radar and mechanical probing, we calculated thaw strain, an index of thaw settlement strength along a transect across the basin that underwent large thaw settlement. We found thaw strains of 10–35% at the basin center, suggesting the seasonal melting of ground ice as a possible mechanism for the large settlement. These findings emphasize the dynamic nature of permafrost landforms, demonstrate the capability of the InSAR technique to remotely monitor surface deformation of individual DTLBs, and illustrate the combination of ground-based and remote sensing observations to estimate thaw strain. Our study highlights the need for better description of the spatial heterogeneity of landscape-scale processes for regional assessment of surface dynamics on Arctic coastal lowlands.

Advanced interferometric gravitational-wave detectors

CERN Document Server

Saulson, Peter R

2019-01-01

Gravitational waves are one of the most exciting and promising emerging areas of physics and astrophysics today. The detection of gravitational waves will rank among the most significant physics discoveries of the 21st century.Advanced Interferometric Gravitational-Wave Detectors brings together many of the world's top experts to deliver an authoritative and in-depth treatment on current and future detectors. Volume I is devoted to the essentials of gravitational-wave detectors, presenting the physical principles behind large-scale precision interferometry, the physics of the underlying noise sources that limit interferometer sensitivity, and an explanation of the key enabling technologies that are used in the detectors. Volume II provides an in-depth look at the Advanced LIGO and Advanced Virgo interferometers that have just finished construction, as well as examining future interferometric detector concepts. This two-volume set will provide students and researchers the comprehensive background needed to und...

Refractive Index Compensation in Over-Determined Interferometric Systems

Directory of Open Access Journals (Sweden)

Zdeněk Buchta

2012-10-01

Full Text Available We present an interferometric technique based on a differential interferometry setup for measurement under atmospheric conditions. The key limiting factor in any interferometric dimensional measurement are fluctuations of the refractive index of air representing a dominating source of uncertainty when evaluated indirectly from the physical parameters of the atmosphere. Our proposal is based on the concept of an over-determined interferometric setup where a reference length is derived from a mechanical frame made from a material with a very low thermal coefficient. The technique allows one to track the variations of the refractive index of air on-line directly in the line of the measuring beam and to compensate for the fluctuations. The optical setup consists of three interferometers sharing the same beam path where two measure differentially the displacement while the third evaluates the changes in the measuring range, acting as a tracking refractometer. The principle is demonstrated in an experimental setup.

Source model for the Copahue volcano magma plumbing system constrained by InSAR surface deformation observations

OpenAIRE

Paul Lundgren; M. Nikkhoo; Sergey V. Samsonov; Pietro Milillo; Fernando Gil-Cruz; Jonathan Lazo

2017-01-01

Tar files for each of the InSAR time series (interferograms used in the GIAnT time series computation as well as the input files and outputs from using GIAnT). GIAnT is an open source InSAR time series code developed at Caltech. The UAVSAR_*.tgz files contain the interferograms from the UAVSAR airborne system that were used in the analysis. The actual model input files require some additional down sampling using resamptool.m a Matlab code developed by Prof. R. Lohman, Cornell Univ.

The management of scarce water resources using GNSS, InSAR ...

African Journals Online (AJOL)

GNSS receivers were run continuously for a period of 133 days between March and August 2014 to detect possible surface subsidence during pumping and artesian free flow extraction of water in the wellfield. Two InSAR scenes were processed, one during the peak period of water extraction from the wellfield and the other ...

Focused-laser interferometric position sensor

International Nuclear Information System (INIS)

Friedman, Stephen J.; Barwick, Brett; Batelaan, Herman

2005-01-01

We describe a simple method to measure the position shifts of an object with a range of tens of micrometers using a focused-laser (FL) interferometric position sensor. In this article we examine the effects of mechanical vibration on FL and Michelson interferometers. We tested both interferometers using vibration amplitudes ranging from 0 to 20 μm. Our FL interferometer has a resolution much better than the diffraction grating periodicities of 10 and 14 μm used in our experiments. A FL interferometer provides improved mechanical stability at the expense of spatial resolution. Our experimental results show that Michelson interferometers cannot be used when the vibration amplitude is more than an optical wavelength. The main purpose of this article is to demonstrate that a focused-laser interferometric position sensor can be used to measure the position shifts of an object on a less sensitive, micrometer scale when the vibration amplitude is too large to use a Michelson interferometer

Geodetic Measurements and Mechanical Models of Cyclic Deformation at Okmok Volcano, Alaska

Science.gov (United States)

Feigl, K.; Masterlark, T.; Lu, Z.; Ohlendorf, S. J.; Thurber, C. H.; Sigmundsson, F.

2009-12-01

The 1997 and 2008 eruptions of Okmok volcano, Alaska, provide a rare opportunity for conducting a rheological experiment to unravel the complex processes associated with magma migration, storage, and eruption in an active volcano. In this experiment, the magma flux during the eruption provides the “impulse” and the subsequent, transient deformation, the “response”. By simulating the impulse, measuring the response, and interpreting the constitutive relations between the two, one can infer the rheology. Okmok is an excellent natural laboratory for such an experiment because a complete cycle of deformation has been monitored using geodetic and seismic means, including: (a) geodetic time series from Interferometric Synthetic Aperture Radar (InSAR) and the Global Positioning System (GPS), (b) earthquake locations; and (c) seismic tomography. We are developing quantitative models using the Finite Element Method (FEM) to simulate the timing and location of the observed seismicity and deformation by accounting for: (a) the geometry and loading of the magma chamber and lava flow, (b) the spatial distribution of material properties; and (c) the constitutive (rheological) relations between stress and strain. Here, we test the hypothesis that the deformation following the 1997 eruption did not reach a steady state before the eruption in 2008. To do so, we iteratively confront the FEM models with the InSAR measurements using the General Inversion of Phase Technique (GIPhT). This approach models the InSAR phase data directly, without unwrapping, as developed, validated, and applied by Feigl and Thurber [Geophys. J. Int., 2009]. By minimizing a cost function that quantifies the misfit between observed and modeled values in terms of “wrapped” phase (with values ranging from -1/2 to +1/2 cycles), GIPhT can estimate parameters in a geophysical model. By avoiding the pitfalls of phase-unwrapping approaches, GIPhT allows the analysis, interpretation and modeling of more

TerraSAR-X InSAR multipass analysis on Venice, Italy)

Science.gov (United States)

Nitti, D. O.; Nutricato, R.; Bovenga, F.; Refice, A.; Chiaradia, M. T.; Guerriero, L.

2009-09-01

The TerraSAR-X (copyright) mission, launched in 2007, carries a new X-band Synthetic Aperture Radar (SAR) sensor optimally suited for SAR interferometry (InSAR), thus allowing very promising application of InSAR techniques for the risk assessment on areas with hydrogeological instability and especially for multi-temporal analysis, such as Persistent Scatterer Interferometry (PSI) techniques, originally developed at Politecnico di Milano. The SPINUA (Stable Point INterferometry over Unurbanised Areas) technique is a PSI processing methodology which has originally been developed with the aim of detection and monitoring of coherent PS targets in non or scarcely-urbanized areas. The main goal of the present work is to describe successful applications of the SPINUA PSI technique in processing X-band data. Venice has been selected as test site since it is in favorable settings for PSI investigations (urban area containing many potential coherent targets such as buildings) and in view of the availability of a long temporal series of TerraSAR-X stripmap acquisitions (27 scenes in all). The Venice Lagoon is affected by land sinking phenomena, whose origins are both natural and man-induced. The subsidence of Venice has been intensively studied for decades by determining land displacements through traditional monitoring techniques (leveling and GPS) and, recently, by processing stacks of ERS/ENVISAT SAR data. The present work is focused on an independent assessment of application of PSI techniques to TerraSAR-X stripmap data for monitoring the stability of the Venice area. Thanks to its orbital repeat cycle of only 11 days, less than a third of ERS/ENVISAT C-band missions, the maximum displacement rate that can be unambiguously detected along the Line-of-Sight (LOS) with TerraSAR-X SAR data through PSI techniques is expected to be about twice the corresponding value of ESA C-band missions, being directly proportional to the sensor wavelength and inversely proportional to the

Archaeological use of Synthetic Aperture Sonar on deepwater wreck sites in Skagerrak

DEFF Research Database (Denmark)

Maarleveld, Thijs J.; Ødegård, Øyvind; Hansen, Roy E.

2018-01-01

Marine archaeological surveying in deep waters has so far been challenging, mainly due to operational and technological constraints. The standard tool has been Side Scan Sonar (SSS) towed behind a surface vessel. Synthetic Aperture Sonar (SAS) technology is not subject to the traditional range....../resolution tradeoff, and produces results of considerably higher quality than traditional SSS. In 2015 and 2016 a comprehensive mapping of wrecks in Skagerrak, a large deepwater area off the south coast of Norway was undertaken, using an interferometric SAS system deployed on an autonomous underwater vehicle...

Stabilizing operation point technique based on the tunable distributed feedback laser for interferometric sensors

Science.gov (United States)

Mao, Xuefeng; Zhou, Xinlei; Yu, Qingxu

2016-02-01

We describe a stabilizing operation point technique based on the tunable Distributed Feedback (DFB) laser for quadrature demodulation of interferometric sensors. By introducing automatic lock quadrature point and wavelength periodically tuning compensation into an interferometric system, the operation point of interferometric system is stabilized when the system suffers various environmental perturbations. To demonstrate the feasibility of this stabilizing operation point technique, experiments have been performed using a tunable-DFB-laser as light source to interrogate an extrinsic Fabry-Perot interferometric vibration sensor and a diaphragm-based acoustic sensor. Experimental results show that good tracing of Q-point was effectively realized.

Application of persistent scatterers interferometry for surface displacements monitoring in N5E open pit iron mine using TerraSAR-X data, in Carajás Province, Amazon region

Directory of Open Access Journals (Sweden)

Filipe Altoé Temporim

Full Text Available ABSTRACT: Carajás Mineral Province, Amazon region, is the most important one in Brazil. Vale S.A. Company has the right to operate in the area of the N5E mine. The work is conducted on rock alteration products of low geomechanical quality related to sandstones, siltstones, and a lateritic cover. In order to monitor ground deformation, 33 TerraSAR-X images covering the period of March 2012-April 2013 were used in the investigation. An interferometric synthetic aperture radar (InSAR approach based on permanent scatterer interferometry (PSI using an interferometric point target analysis algorithm was applied. Results demonstrated that most of the area was considered stable during the time span of the image acquisition. However, persistent scatterers (PSs with high deformation rates were mapped over a landfill probably related to settlements. To validate the PSI data, graphs were generated with the displaced information based on topographic measurements in the field. The graphs showed that the surface deformations during TSX-1 runway coverage are within the miner’s safety threshold and do not present a risk of major problems. The PSI data provided a synoptic and detailed view of the deformation process that affects the mining complex without the need of field campaign or instrumentation.

Plan for Living on a Restless Planet Sets NASA's Solid Earth Agenda

Science.gov (United States)

Solomon, Sean C.; Baker, Victor R.; Bloxham, Jeremy; Booth, Jeffrey; Donnellan, Andrea; Elachi, Charles; Evans, Diane; Rignot, Eric; Burbank, Douglas; Chao, Benjamin F.; Chave, Alan; Gillespie, Alan; Herring, Thomas; Jeanloz, Raymond; LaBrecque, John; Minster, Bernard; Pittman, Walter C., III; Simons, Mark; Turcotte, Donald L.; Zoback, Mary Lou C.

What are the most important challenges facing solid Earth science today and over the next two decades? And what is the best approach for NASA, in partnership with other agencies, to address those challenges? A new report, Living on a Restless Planet, provides a blueprint for answering these questions. The top priority for a new spacecraft mission in the area of solid Earth science over the next 5 years, according to this report, is a satellite dedicated to Interferometric Synthetic Aperture Radar (InSAR). At the request of NASA, the Solid Earth Science Working Group (SESWG) developed a strategy for the highest priority objectives in solid Earth science for the space agency over the next 25 years. The strategy addresses six challenges that are of fundamental scientific importance, have strong implications for society, and are amenable to substantial progress through a concerted series of scientific observations from space.

Combining InSAR and GPS to determine transient movement and thickness of a seasonally active low-gradient translational landslide

Science.gov (United States)

Hu, Xie; Lu, Zhong; Pierson, Thomas C.; Kramer, Rebecca; George, David L.

2018-01-01

The combined application of continuous Global Positioning System data (high temporal resolution) with spaceborne interferometric synthetic aperture radar data (high spatial resolution) can reveal much more about the complexity of large landslide movement than is possible with geodetic measurements tied to only a few specific measurement sites. This approach is applied to an ~4 km2 reactivated translational landslide in the Columbia River Gorge (Washington State), which moves mainly during the winter rainy season. Results reveal the complex three-dimensional shape of the landslide mass, how onset of sliding relates to cumulative rainfall, how surface velocity during sliding varies with location on the topographically complex landslide surface, and how the ground surface subsides slightly in weeks prior to downslope sliding.

Interferometric study of the small magellanic cloud

International Nuclear Information System (INIS)

Torres, G.; Carranza, G.J.

1986-01-01

Hα interferometric observations of the general radial velocity field in the small magellanic cloud are being carried out. We present preliminary results in reasonable agreement with H I measurements. (author)

Using InSAR for Characterizing Pyroclastic Flow Deposits at Augustine Volcano Across Two Eruptive Cycles

Science.gov (United States)

McAlpin, D. B.; Meyer, F. J.; Lu, Z.; Beget, J. E.

2014-12-01

Augustine Island is a small, 8x11 km island in South Central Alaska's lower Cook Inlet. It is approximately 280 km southwest of Anchorage, and occupied entirely by its namesake Augustine Volcano. At Augustine Volcano, SAR data suitable for interferometry is available from 1992 to 2005, from March 2006 to April 2007, and from July 2007 to October 2010. Its last two eruptive episodes, in 1986 and 2006, resulted in substantial pyroclastic flow deposits (PFDs) on the Volcano's north flank. Earlier InSAR analyses of the area, from 1992-1999, identified local subsidence, but no volcano-wide deformation indicative of magma-chamber evacuation. In contrast to previous studies, we use InSAR data to determine a range of geophysical parameters for PFDs emplaced during the Augustine's two most recent eruption cycles. Based on InSAR measurements between 1992 and 2010, we reconstruct the deformation behavior of PFDs emplaced during Augustine's last two eruption cycles. Using a combination of InSAR measurements and modeling, we determine the thickness and long-term deformation of overlaying pyroclastic flow deposits emplaced in 1986 and 2006. Consistent with previous observations of pyroclastic flows, we found that the PFDs on Augustine Island rapidly subsided after emplacement due to an initial compaction of the material. We determined the length of this initial settling period and measured the compaction rate. Subsequent to this initial rapid subsidence, we found that PFD deformation slowed to a more persistent, linear, long-term rate, related to cooling of the deposits. We established that the deposits' contraction rate is linearly related to their thickness and measured the contraction rate. Finally, a study of long term coherence properties of the Augustine PFDs showed remarkable stability of the surface over long time periods. This information provides clues on the structural properties and composition of the emplaced material.

Groundwater-related Land Deformation over the Mega Aquifer System in Saudi Arabia: Inferences from InSAR, GRACE, Earthquake records, Field, and Spatial Data Analysis.

Science.gov (United States)

Othman, A.; Sultan, M.; Becker, R.; Sefry, S.; Alharbi, T.; Alharbi, H.; Gebremichael, E.

2017-12-01

Land deformational features (subsidence, and earth fissures, etc.) are being reported from many locations over the Lower Mega Aquifer System (LMAS) in the central and northern parts of Saudi Arabia. We applied an integrated approach (remote sensing, geodesy, GIS, geology, hydrogeology, and geotechnical) to identify nature, intensity, spatial distribution, and factors controlling the observed deformation. A three-fold approach was adopted to accomplish the following: (1) investigate, identify, and verify the land deformation through fieldwork; (2) assess the spatial and temporal distribution of land deformation and quantify deformation rates using Interferometric Synthetic Aperture Radar (InSAR) and Persistent Scatterer Interferometry (PSI) methods (period: 2003 to 2012); (3) generate a GIS database to host all relevant data and derived products (remote sensing, geology, geotechnical, GPS, groundwater extraction rates, and water levels, etc.) and to correlate these spatial and temporal datasets in search of causal effects. The following observations are consistent with deformational features being caused by excessive groundwater extraction: (1) distribution of deformational features correlated spatially and temporally with increased agricultural development and groundwater extraction, and with the decline in groundwater levels and storage; (2) earthquake events (1.5 - 5.5 M) increased from one event at the beginning of the agricultural development program in 1980 (average annual extraction [ANE]: 1-2 km³/yr), to 13 events per year between 1995 to 2005, the decade that witnessed the largest expansion in groundwater extraction (ANE: >6.4 km³) and land reclamation using groundwater resources; and (3) earthquake epicenters and the deformation sites are found largely within areas bound by the Kahf fault system suggesting that faults play a key role in the deformation phenomenon. Findings from the PSI investigation revealed high, yet irregularly distributed, subsidence

Different scale land subsidence and ground fissure monitoring with multiple InSAR techniques over Fenwei basin, China

Directory of Open Access Journals (Sweden)

C. Zhao

2015-11-01

Full Text Available Fenwei basin, China, composed by several sub-basins, has been suffering severe geo-hazards in last 60 years, including large scale land subsidence and small scale ground fissure, which caused serious infrastructure damages and property losses. In this paper, we apply different InSAR techniques with different SAR data to monitor these hazards. Firstly, combined small baseline subset (SBAS InSAR method and persistent scatterers (PS InSAR method is used to multi-track Envisat ASAR data to retrieve the large scale land subsidence covering entire Fenwei basin, from which different land subsidence magnitudes are analyzed of different sub-basins. Secondly, PS-InSAR method is used to monitor the small scale ground fissure deformation in Yuncheng basin, where different spatial deformation gradient can be clearly discovered. Lastly, different track SAR data are contributed to retrieve two-dimensional deformation in both land subsidence and ground fissure region, Xi'an, China, which can be benefitial to explain the occurrence of ground fissure and the correlation between land subsidence and ground fissure.

Label-free and live cell imaging by interferometric scattering microscopy.

Science.gov (United States)

Park, Jin-Sung; Lee, Il-Buem; Moon, Hyeon-Min; Joo, Jong-Hyeon; Kim, Kyoung-Hoon; Hong, Seok-Cheol; Cho, Minhaeng

2018-03-14

Despite recent remarkable advances in microscopic techniques, it still remains very challenging to directly observe the complex structure of cytoplasmic organelles in live cells without a fluorescent label. Here we report label-free and live-cell imaging of mammalian cell, Escherischia coli , and yeast, using interferometric scattering microscopy, which reveals the underlying structures of a variety of cytoplasmic organelles as well as the underside structure of the cells. The contact areas of the cells attached onto a glass substrate, e.g. , focal adhesions and filopodia, are clearly discernible. We also found a variety of fringe-like features in the cytoplasmic area, which may reflect the folded structures of cytoplasmic organelles. We thus anticipate that the label-free interferometric scattering microscopy can be used as a powerful tool to shed interferometric light on in vivo structures and dynamics of various intracellular phenomena.

Magma injection into a long-lived reservoir to explain geodetically measured uplift: Application to the 2007-2014 unrest episode at Laguna del Maule volcanic field, Chile.

Science.gov (United States)

Le Mével, Hélène; Gregg, Patricia M; Feigl, Kurt L

2016-08-01

Moving beyond the widely used kinematic models for the deformation sources, we present a new dynamic model to describe the process of injecting magma into an existing magma reservoir. To validate this model, we derive an analytical solution and compare its results to those calculated using the Finite Element Method. A Newtonian fluid characterized by its viscosity, density, and overpressure (relative to the lithostatic value) flows through a vertical conduit, intruding into a reservoir embedded in an elastic domain, leading to an increase in reservoir pressure and time-dependent surface deformation. We apply our injection model to Interferometric Synthetic Aperture Radar (InSAR) data from the ongoing unrest episode at Laguna del Maule (Chile) volcanic field that started in 2007. Using a grid search optimization, we minimize the misfit to the InSAR displacement data and vary the three parameters governing the analytical solution: the characteristic timescale τ P for magma propagation, the maximum injection pressure, and the inflection time when the acceleration switches from positive to negative. For a spheroid with semimajor axis a = 6200 m, semiminor axis c = 100 m, located at a depth of 4.5 km in a purely elastic half-space, the best fit to the InSAR displacement data occurs for τ P =9.5 years and an injection pressure rising up to 11.5 MPa for 2 years. The volume flow rate increased to 1.2 m 3 /s for 2 years and then decreased to 0.7 m 3 /s in 2014. In 7.3 years, at least 187 × 10 6 m 3 of magma was injected.

Observations and modelling of inflation in the Lazufre volcanic region, South America

Science.gov (United States)

Pearse, J.; Lundgren, P.

2010-12-01

The Central Volcanic Zone (CVZ) is an active volcanic arc in the central Andes, extending through Peru, southwestern Bolivia, Chile, and northwestern Argentina [De Silva, 1989; De Silva and Francis, 1991]. The CVZ includes a number of collapsed calderas, remnants of catastrophic eruptions, which are now thought to be inactive. However, recent Interferometric Synthetic Aperture Radar (InSAR) observations [Pritchard and Simons, 2004] show surface deformation occurring at some of these large ancient volcanic regions, indicating that magma chambers are slowly inflating beneath the surface. The mechanisms responsible for the initiation and growth of large midcrustal magma chambers remains poorly understood, and InSAR provides an opportunity for us to observe volcanic systems in remote regions that are otherwise difficult to monitor and observe. The Lastarria-Cordon del Azufre ("Lazufre" [Pritchard and Simons, 2002]) volcanic area is one such complex showing recent deformation, with average surface uplift rates of approximately 2.5 cm/year [Froger et al., 2007; Ruch et al, 2008]. We have processed InSAR data from ERS-1/2 and Envisat in the Lazufre volcanic area, including both ascending and descending satellite tracks. Time series analysis of the data shows steady uplift beginning in about 2000, continuing into 2010. We use boundary-element elastic models to invert for the depth and shape of the magmatic source responsible for the surface deformation. Given data from both ascending and descending tracks, we are able to resolve the ambiguity between the source depth and size, and constrain the geometry of the inflating magma source. Finite element modelling allows us to understand the effect of viscoelasticity on the development of the magma chamber.

Locating and defining underground goaf caused by coal mining from space-borne SAR interferometry

Science.gov (United States)

Yang, Zefa; Li, Zhiwei; Zhu, Jianjun; Yi, Huiwei; Feng, Guangcai; Hu, Jun; Wu, Lixin; Preusse, Alex; Wang, Yunjia; Papst, Markus

2018-01-01

It is crucial to locate underground goafs (i.e., mined-out areas) resulting from coal mining and define their spatial dimensions for effectively controlling the induced damages and geohazards. Traditional geophysical techniques for locating and defining underground goafs, however, are ground-based, labour-consuming and costly. This paper presents a novel space-based method for locating and defining the underground goaf caused by coal extraction using Interferometric Synthetic Aperture Radar (InSAR) techniques. As the coal mining-induced goaf is often a cuboid-shaped void and eight critical geometric parameters (i.e., length, width, height, inclined angle, azimuth angle, mining depth, and two central geodetic coordinates) are capable of locating and defining this underground space, the proposed method reduces to determine the eight geometric parameters from InSAR observations. Therefore, it first applies the Probability Integral Method (PIM), a widely used model for mining-induced deformation prediction, to construct a functional relationship between the eight geometric parameters and the InSAR-derived surface deformation. Next, the method estimates these geometric parameters from the InSAR-derived deformation observations using a hybrid simulated annealing and genetic algorithm. Finally, the proposed method was tested with both simulated and two real data sets. The results demonstrate that the estimated geometric parameters of the goafs are accurate and compatible overall, with averaged relative errors of approximately 2.1% and 8.1% being observed for the simulated and the real data experiments, respectively. Owing to the advantages of the InSAR observations, the proposed method provides a non-contact, convenient and practical method for economically locating and defining underground goafs in a large spatial area from space.

Observations and Modeling of Coseismic and Postseismic Deformation Due To the 2015 Mw 7.8 Gorkha (Nepal) Earthquake

Science.gov (United States)

Wang, Kang; Fialko, Yuri

2018-01-01

We use space geodetic data to investigate coseismic and postseismic deformation due to the 2015 Mw 7.8 Gorkha earthquake that occurred along the central Himalayan arc. Because the earthquake area is characterized by strong variations in surface relief and material properties, we developed finite element models that explicitly account for topography and 3-D elastic structure. We computed the line-of-sight displacement histories from three tracks of the Sentinel-1A/B Interferometric Synthetic Aperture Radar (InSAR) satellites, using persistent scatter method. InSAR observations reveal an uplift of up to ˜70 mm over ˜20 months after the main shock, concentrated primarily at the downdip edge of the ruptured asperity. GPS observations also show uplift, as well as southward movement in the epicentral area, qualitatively similar to the coseismic deformation pattern. Kinematic inversions of GPS and InSAR data and forward models of stress-driven creep suggest that the observed postseismic transient is dominated by afterslip on a downdip extension of the seismic rupture. A poroelastic rebound may have contributed to the observed uplift and southward motion, but the predicted surface displacements are small. We also tested a wide range of viscoelastic relaxation models, including 1-D and 3-D variations in the viscosity structure. Models of a low-viscosity channel previously invoked to explain the long-term uplift and variations in topography at the plateau margins predict opposite signs of horizontal and vertical displacements compared to those observed. Our results do not preclude a possibility of deep-seated viscoelastic response beneath southern Tibet with a characteristic relaxation time greater than the observation period (2 years).

Interferometric crosstalk suppression using polarization multiplexing technique and an SOA

DEFF Research Database (Denmark)

Liu, Fenghai; Xueyan, Zheng; Pedersen, Rune Johan Skullerud

2000-01-01

Interferometric crosstalk can be greatly suppressed at 10Gb/s and 20Gb/s by using a gain saturated SOA and a polarization multiplexing technique that eliminates impairments like waveform and extinction ratio degradation from the SOA.......Interferometric crosstalk can be greatly suppressed at 10Gb/s and 20Gb/s by using a gain saturated SOA and a polarization multiplexing technique that eliminates impairments like waveform and extinction ratio degradation from the SOA....

Effects of Target Positioning Error on Motion Compensation for Airborne Interferometric SAR

Directory of Open Access Journals (Sweden)

Li Yin-wei

2013-12-01

Full Text Available The measurement inaccuracies of Inertial Measurement Unit/Global Positioning System (IMU/GPS as well as the positioning error of the target may contribute to the residual uncompensated motion errors in the MOtion COmpensation (MOCO approach based on the measurement of IMU/GPS. Aiming at the effects of target positioning error on MOCO for airborne interferometric SAR, the paper firstly deduces a mathematical model of residual motion error bring out by target positioning error under the condition of squint. And the paper analyzes the effects on the residual motion error caused by system sampling delay error, the Doppler center frequency error and reference DEM error which result in target positioning error based on the model. Then, the paper discusses the effects of the reference DEM error on the interferometric SAR image quality, the interferometric phase and the coherent coefficient. The research provides theoretical bases for the MOCO precision in signal processing of airborne high precision SAR and airborne repeat-pass interferometric SAR.

Ongoing Deformation of Sinkholes in Wink, Texas, Observed by Time-Series Sentinel-1A SAR Interferometry (Preliminary Results

Directory of Open Access Journals (Sweden)

Jin-Woo Kim

2016-04-01

Full Text Available Spatiotemporal deformation of existing sinkholes and the surrounding region in Wink, TX are probed using time-series interferometric synthetic aperture radar (InSAR methods with radar images acquired from the Sentinel-1A satellite launched in April 2014. The two-dimensional deformation maps, calculated using InSAR observations from ascending and descending tracks, reveal that much of the observed deformation is vertical. Our results indicate that the sinkholes are still influenced by ground depression, implying that the sinkholes continue to expand. Particularly, a region 1 km northeast of sinkhole #2 is sinking at a rate of up to 13 cm/year, and its aerial extent has been enlarged in the past eight years when compared with a previous survey. Furthermore, there is a high correlation between groundwater level and surficial subsidence during the summer months, representing the complicated characteristics of sinkhole deformation under the influence of successive roof failures in underlying cavities. We also modeled the sinkhole deformation in a homogenous elastic half-space with two dislocation sources, and the ground depression above cavities could be numerically analyzed. Measurements of ongoing deformation in sinkholes and assessments of the stability of the land surface at sinkhole-prone locations in near real-time, are essential for mitigating the threat posed to people and property by the materialization of sinkholes.

The InSAeS4 Airborne X-Band Interferometric SAR System: A First Assessment on Its Imaging and Topographic Mapping Capabilities

Directory of Open Access Journals (Sweden)

Stefano Perna

2016-01-01

Full Text Available We present in this work a first assessment of the imaging and topographic mapping capabilities of the InSAeS4 system, which is a single-pass interferometric airborne X-Band Synthetic Aperture Radar (SAR. In particular, we first provide a brief description of the InSAeS4 sensor. Then, we discuss the results of our analysis on the SAR and interferometric SAR products relevant to the first flight-test campaign. More specifically, we have exploited as reference the GPS measurements relevant to nine Corner Reflectors (CRs deployed over the illuminated area during the campaign and a laser scanner Digital Elevation Model (DEM. From the analysis carried out on the CRs we achieved a mean geometric resolution, for the SAR products, of about 0.14 m in azimuth and 0.49 m in range, a positioning misalignment with standard deviation of 0.07 m in range and 0.08 m in azimuth, and a height error with standard deviation of 0.51 m. From the comparison with the laser scanner DEM we estimated a height error with standard deviation of 1.57 m.

Secure space-to-space interferometric communications and its nexus to the physics of quantum entanglement

Science.gov (United States)

Duarte, F. J.

2016-12-01

The history of the probability amplitude equation | ψ > = ( | x , y > - | y , x > ) applicable to quanta pairs, propagating in different directions with entangled polarizations, is reviewed and traced back to the 1947-1949 period. The interferometric Dirac foundations common to | ψ > = ( | x , y > - | y , x > ) and the generalized N-slit interferometric equation, for indistinguishable quanta, are also described. The results from a series of experiments on N-slit laser interferometers, with intra interferometric propagation paths up to 527 m, are reviewed. Particular attention is given to explain the generation of interferometric characters, for secure space-to-space communications, which immediately collapse on attempts of interception. The design of a low divergence N-slit laser interferometer for low Earth orbit-low Earth orbit (LEO-LEO), and LEO-geostationary Earth orbit (LEO-GEO), secure interferometric communications is described and a weight assessment is provided.

The ground subsidence anomaly investigation around Ambala, India by InSAR and spatial analyses: Why and how the Ambala city behaves as the most significant subsidence region in the Northwest India?

Science.gov (United States)

Kim, J.; Lin, S. Y.; Tsai, Y.; Singh, S.; Singh, T.

2017-12-01

A large ground deformation which may be caused by a significant groundwater depletion of the Northwest India Aquifer has been successfully observed throughout space geodesy techniques (Tsai et al, 2016). Employing advanced time-series ScanSAR InSAR analysis and Gravity Recovery and Climate Experiment (GRACE) satellites data, it revealed 400-km wide huge ground deformation in and around Haryana. It was further notified that the Ambala city located in northern Haryana district shown the most significant ground subsidence with maximum cumulative deformation up to 0.2 meters within 3 years in contrast to the nearby cities such as Patiala and Chandigarh that did not present similar subsidence. In this study, we investigated the details of "Ambala Anomaly" employing advanced time-series InSAR and spatial analyses together with local geology and anthropogenic contexts and tried to identify the factors causing such a highly unique ground deformation pattern. To explore the pattern and trend of Ambala' subsidence, we integrated the time-series deformation results of both ascending L-band PALSAR-1 (Phased Array type L-band Synthetic Aperture Radar) from 2007/1 to 2011/1 and descending C-band ASAR (Advanced Synthetic Aperture Radar) from 2008/9 to 2010/8 to process the 3D decomposition, expecting to reveal the asymmetric movement of the surface. In addition. The spatial analyses incorporating detected ground deformations and local economical/social factors were then applied for the interpretation of "Ambala Anomaly". The detailed interrelationship of driving factors of the "Ambala Anomaly" and the spatial pattern of corresponding ground subsidence will be further demonstrated. After all, we determined the uniqueness of Ambala subsidence possibly be driven by both anthropogenic behaviors including the rapid growth rate of population and constructing of industrial centers as well as the natural geological characteristics and sediment deposition.

High-accuracy single-pass InSAR DEM for large-scale flood hazard applications

Science.gov (United States)

Schumann, G.; Faherty, D.; Moller, D.

2017-12-01

In this study, we used a unique opportunity of the GLISTIN-A (NASA airborne mission designed to characterizing the cryosphere) track to Greenland to acquire a high-resolution InSAR DEM of a large area in the Red River of the North Basin (north of Grand Forks, ND, USA), which is a very flood-vulnerable valley, particularly in spring time due to increased soil moisture content near state of saturation and/or, typical for this region, snowmelt. Having an InSAR DEM that meets flood inundation modeling and mapping requirements comparable to LiDAR, would demonstrate great application potential of new radar technology for national agencies with an operational flood forecasting mandate and also local state governments active in flood event prediction, disaster response and mitigation. Specifically, we derived a bare-earth DEM in SAR geometry by first removing the inherent far range bias related to airborne operation, which at the more typical large-scale DEM resolution of 30 m has a sensor accuracy of plus or minus 2.5 cm. Subsequently, an intelligent classifier based on informed relationships between InSAR height, intensity and correlation was used to distinguish between bare-earth, roads or embankments, buildings and tall vegetation in order to facilitate the creation of a bare-earth DEM that would meet the requirements for accurate floodplain inundation mapping. Using state-of-the-art LiDAR terrain data, we demonstrate that capability by achieving a root mean squared error of approximately 25 cm and further illustrating its applicability to flood modeling.

Physics of interferometric gravitational wave detectors

Indian Academy of Sciences (India)

The Caltech-MIT joint LIGO project is operating three long-baseline interferometers (one of 2 km and two of 4 km) in order to unambiguously measure the infinitesimal displacements of isolated test masses which convey the signature of gravitational waves from astrophysical sources. An interferometric gravitational wave ...

Frequency-resolved interferometric measurement of local density fluctuations for turbulent combustion analysis

International Nuclear Information System (INIS)

Köberl, S; Giuliani, F; Woisetschläger, J; Fontaneto, F

2010-01-01

A validation of a novel interferometric measurement technique for the frequency-resolved detection of local density fluctuation in turbulent combustion analysis was performed in this work. Two laser vibrometer systems together with a signal analyser were used to obtain frequency spectra of density fluctuations across a methane-jet flame. Since laser vibrometry is based on interferometric techniques, the derived signals are path-integrals along the measurement beam. To obtain local frequency spectra of density fluctuations, long-time-averaged measurements from each of the two systems were performed using correlation functions and cross spectra. Results were compared to data recorded by standard interferometric techniques for validation purposes. Additionally, Raman scattering and laser Doppler velocimetry were used for flame characterization

Subsidence (2004-2009) in and near lakebeds of the Mojave River and Morongo groundwater basins, southwest Mojave Desert, California

Science.gov (United States)

Solt, Mike; Sneed, Michelle

2014-01-01

Subsidence, in the vicinity of dry lakebeds, within the Mojave River and Morongo groundwater basins of the southwest Mojave Desert has been measured by Interferometric Synthetic Aperture Radar (InSAR). The investigation has focused on determining the location, extent, and magnitude of changes in land-surface elevation. In addition, the relation of changes in land-surface elevation to changes in groundwater levels and lithology was explored. This report is the third in a series of reports investigating land-surface elevation changes in the Mojave and Morongo Groundwater Basins, California. The first report, U.S. Geological Survey (USGS) Water-Resources Investigations Report 03-4015 by Sneed and others (2003), describes historical subsidence and groundwater-level changes in the southwest Mojave Desert from 1969 to 1999. The second report, U.S. Geological Survey Water-Resources Investigations Report 07-5097, an online interactive report and map, by Sneed and Brandt (2007), describes subsidence and groundwater-level changes in the southwest Mojave Desert from 1999 to 2004. The purpose of this report is to document an updated assessment of subsidence in these lakebeds and selected neighboring areas from 2004 to 2009 as measured by InSAR methods. In addition, continuous Global Positioning System (GPS)(2005-10), groundwater level (1951-2010), and lithologic data, if available, were used to characterize compaction mechanisms in these areas. The USGS California Water Science Center’s interactive website for the Mojave River and Morongo groundwater basins was created to centralize information pertaining to land subsidence and water levels and to allow readers to access available data and related reports online. An interactive map of land subsidence and water levels in the Mojave River and Morongo groundwater basins displays InSAR interferograms, subsidence areas, subsidence contours, hydrographs, well information, and water-level contours. Background information, including

Investigation on Insar Time Series Deformation Model Considering Rheological Parameters for Soft Clay Subgrade Monitoring

Science.gov (United States)

Xing, X.; Yuan, Z.; Chen, L. F.; Yu, X. Y.; Xiao, L.

2018-04-01

The stability control is one of the major technical difficulties in the field of highway subgrade construction engineering. Building deformation model is a crucial step for InSAR time series deformation monitoring. Most of the InSAR deformation models for deformation monitoring are pure empirical mathematical models, without considering the physical mechanism of the monitored object. In this study, we take rheology into consideration, inducing rheological parameters into traditional InSAR deformation models. To assess the feasibility and accuracy for our new model, both simulation and real deformation data over Lungui highway (a typical highway built on soft clay subgrade in Guangdong province, China) are investigated with TerraSAR-X satellite imagery. In order to solve the unknows of the non-linear rheological model, three algorithms: Gauss-Newton (GN), Levenberg-Marquarat (LM), and Genetic Algorithm (GA), are utilized and compared to estimate the unknown parameters. Considering both the calculation efficiency and accuracy, GA is chosen as the final choice for the new model in our case study. Preliminary real data experiment is conducted with use of 17 TerraSAR-X Stripmap images (with a 3-m resolution). With the new deformation model and GA aforementioned, the unknown rheological parameters over all the high coherence points are obtained and the LOS deformation (the low-pass component) sequences are generated.

Expressway deformation mapping using high-resolution TerraSAR-X images

KAUST Repository

Shi, Xuguo

2014-01-27

Monitoring deformation of linear infrastructures such as expressway and railway caused by natural processes or anthropogenic activities is a vital task to ensure the safety of human lives and properties. Interferometric Synthetic Aperture Radar (InSAR) has been widely recognized as an effective technology to carry out large-area surface deformation mapping. However, its application in linear infrastructure deformation monitoring has not been intensively studied till now. In this article, a modified Small BAseline Subset (SBAS) method is proposed to retrieve the deformation patterns of the expressway. In our method, only the point-like targets identified on the expressway were kept in our analysis, and two complementary subsets of interferograms were formed to better separate the signals of height error and deformation from inteferometric phase observations. We successfully applied this method with multitemporal high-resolution TerraSAR-X images to retrieve the spatialoral pattern of surface deformation along the Beian-Heihe expressway that is located in island-permafrost areas and threatened by geohazards. © 2014 Taylor & Francis.

Expressway deformation mapping using high-resolution TerraSAR-X images

KAUST Repository

Shi, Xuguo; Liao, Mingsheng; Wang, Teng; Zhang, Lu; Shan, Wei; Wang, Chunjiao

2014-01-01

Monitoring deformation of linear infrastructures such as expressway and railway caused by natural processes or anthropogenic activities is a vital task to ensure the safety of human lives and properties. Interferometric Synthetic Aperture Radar (InSAR) has been widely recognized as an effective technology to carry out large-area surface deformation mapping. However, its application in linear infrastructure deformation monitoring has not been intensively studied till now. In this article, a modified Small BAseline Subset (SBAS) method is proposed to retrieve the deformation patterns of the expressway. In our method, only the point-like targets identified on the expressway were kept in our analysis, and two complementary subsets of interferograms were formed to better separate the signals of height error and deformation from inteferometric phase observations. We successfully applied this method with multitemporal high-resolution TerraSAR-X images to retrieve the spatialoral pattern of surface deformation along the Beian-Heihe expressway that is located in island-permafrost areas and threatened by geohazards. © 2014 Taylor & Francis.

Applicability Assessment of Uavsar Data in Wetland Monitoring: a Case Study of Louisiana Wetland

Science.gov (United States)

Zhao, J.; Niu, Y.; Lu, Z.; Yang, J.; Li, P.; Liu, W.

2018-04-01

Wetlands are highly productive and support a wide variety of ecosystem goods and services. Monitoring wetland is essential and potential. Because of the repeat-pass nature of satellite orbit and airborne, time-series of remote sensing data can be obtained to monitor wetland. UAVSAR is a NASA L-band synthetic aperture radar (SAR) sensor compact pod-mounted polarimetric instrument for interferometric repeat-track observations. Moreover, UAVSAR images can accurately map crustal deformations associated with natural hazards, such as volcanoes and earthquakes. And its polarization agility facilitates terrain and land-use classification and change detection. In this paper, the multi-temporal UAVSAR data are applied for monitoring the wetland change. Using the multi-temporal polarimetric SAR (PolSAR) data, the change detection maps are obtained by unsupervised and supervised method. And the coherence is extracted from the interfometric SAR (InSAR) data to verify the accuracy of change detection map. The experimental results show that the multi-temporal UAVSAR data is fit for wetland monitor.

Phase-ramp reduction in interseismic interferograms from pixel-offsets

KAUST Repository

Wang, Teng; Jonsson, Sigurjon

2014-01-01

Interferometric synthetic aperture radar (InSAR) is increasingly used to measure interseismic deformation. Inaccurate satellite-orbit information, expressed as phase ramps across interseismic interferograms, is believed to be one of the main sources of error in such measurements. However, many interferograms exhibit higher phase gradients than expected from the reported orbital accuracy, suggesting that there are other error sources. Here, we show that interferogram phase ramps are in part caused by uncorrected satellite timing-parameter errors. We propose a two-step approach to reduce the phase ramps using pixel-offsets estimated between SAR amplitude images. The first step involves using a digital elevation model (DEM) to estimate absolute timing-parameter errors for the reference image of the SAR dataset and the second step updates the timing parameters of the master image for each interferogram. We demonstrate a clear ramp reduction on interseismic interferograms covering the North Anatolian Fault in eastern Turkey. The resulting interferograms show clear signs of interseismic deformation even before stacking. © 2014 IEEE.

Phase-ramp reduction in interseismic interferograms from pixel-offsets

KAUST Repository

Wang, Teng

2014-05-01

Interferometric synthetic aperture radar (InSAR) is increasingly used to measure interseismic deformation. Inaccurate satellite-orbit information, expressed as phase ramps across interseismic interferograms, is believed to be one of the main sources of error in such measurements. However, many interferograms exhibit higher phase gradients than expected from the reported orbital accuracy, suggesting that there are other error sources. Here, we show that interferogram phase ramps are in part caused by uncorrected satellite timing-parameter errors. We propose a two-step approach to reduce the phase ramps using pixel-offsets estimated between SAR amplitude images. The first step involves using a digital elevation model (DEM) to estimate absolute timing-parameter errors for the reference image of the SAR dataset and the second step updates the timing parameters of the master image for each interferogram. We demonstrate a clear ramp reduction on interseismic interferograms covering the North Anatolian Fault in eastern Turkey. The resulting interferograms show clear signs of interseismic deformation even before stacking. © 2014 IEEE.

Characterizing the deformation of reservoirs using interferometry, gravity, and seismic analyses

Science.gov (United States)

Schiek, Cara Gina

In this dissertation, I characterize how reservoirs deform using surface and subsurface techniques. The surface technique I employ is radar interferometry, also known as InSAR (Interferometric Synthetic Aperture Radar). The subsurface analyses I explore include gravity modeling and seismic techniques consisting of determining earthquake locations from a small-temporary seismic network of six seismometers. These techniques were used in two different projects to determine how reservoirs deform in the subsurface and how this deformation relates to its remotely sensed surface deformation. The first project uses InSAR to determine land subsidence in the Mimbres basin near Deming, NM. The land subsidence measurements are visually compared to gravity models in order to determine the influence of near surface faults on the subsidence and the physical properties of the aquifers in these basins. Elastic storage coefficients were calculated for the Mimbres basin to aid in determining the stress regime of the aquifers. In the Mimbres basin, I determine that it is experiencing elastic deformation at differing compaction rates. The west side of the Mimbres basin is deforming faster, 17 mm/yr, while the east side of the basin is compacting at a rate of 11 mm/yr. The second project focuses on San Miguel volcano, El Salvador. Here, I integrate InSAR with earthquake locations using surface deformation forward modeling to investigate the explosive volcanism in this region. This investigation determined the areas around the volcano that are undergoing deformation, and that could lead to volcanic hazards such as slope failure from a fractured volcano interior. I use the earthquake epicenters with field data to define the subsurface geometry of the deformation source, which I forward model to produce synthetic interferograms. Residuals between the synthetic and observed interferograms demonstrate that the observed deformation is a direct result of the seismic activity along the San

Spatiotemporal Patterns of Precipitation-Modulated Landslide Deformation From Independent Component Analysis of InSAR Time Series

Science.gov (United States)

Cohen-Waeber, J.; Bürgmann, R.; Chaussard, E.; Giannico, C.; Ferretti, A.

2018-02-01

Long-term landslide deformation is disruptive and costly in urbanized environments. We rely on TerraSAR-X satellite images (2009-2014) and an improved data processing algorithm (SqueeSAR™) to produce an exceptionally dense Interferometric Synthetic Aperture Radar ground deformation time series for the San Francisco East Bay Hills. Independent and principal component analyses of the time series reveal four distinct spatial and temporal surface deformation patterns in the area around Blakemont landslide, which we relate to different geomechanical processes. Two components of time-dependent landslide deformation isolate continuous motion and motion driven by precipitation-modulated pore pressure changes controlled by annual seasonal cycles and multiyear drought conditions. Two components capturing more widespread seasonal deformation separate precipitation-modulated soil swelling from annual cycles that may be related to groundwater level changes and thermal expansion of buildings. High-resolution characterization of landslide response to precipitation is a first step toward improved hazard forecasting.

The fresnel interferometric imager

Science.gov (United States)

Koechlin, Laurent; Serre, Denis; Deba, Paul; Pelló, Roser; Peillon, Christelle; Duchon, Paul; Gomez de Castro, Ana Ines; Karovska, Margarita; Désert, Jean-Michel; Ehrenreich, David; Hebrard, Guillaume; Lecavelier Des Etangs, Alain; Ferlet, Roger; Sing, David; Vidal-Madjar, Alfred

2009-03-01

The Fresnel Interferometric Imager has been proposed to the European Space Agency (ESA) Cosmic Vision plan as a class L mission. This mission addresses several themes of the CV Plan: Exoplanet study, Matter in extreme conditions, and The Universe taking shape. This paper is an abridged version of the original ESA proposal. We have removed most of the technical and financial issues, to concentrate on the instrumental design and astrophysical missions. The instrument proposed is an ultra-lightweight telescope, featuring a novel optical concept based on diffraction focussing. It yields high dynamic range images, while releasing constraints on positioning and manufacturing of the main optical elements. This concept should open the way to very large apertures in space. In this two spacecraft formation-flying instrument, one spacecraft holds the focussing element: the Fresnel interferometric array; the other spacecraft holds the field optics, focal instrumentation, and detectors. The Fresnel array proposed here is a 3.6 ×3.6 m square opaque foil punched with 105 to 106 void “subapertures”. Focusing is achieved with no other optical element: the shape and positioning of the subapertures (holes in the foil) is responsible for beam combining by diffraction, and 5% to 10% of the total incident light ends up into a sharp focus. The consequence of this high number of subapertures is high dynamic range images. In addition, as it uses only a combination of vacuum and opaque material, this focussing method is potentially efficient over a very broad wavelength domain. The focal length of such diffractive focussing devices is wavelength dependent. However, this can be corrected. We have tested optically the efficiency of the chromatism correction on artificial sources (500 < λ < 750 nm): the images are diffraction limited, and the dynamic range measured on an artificial double source reaches 6.2 10 - 6. We have also validated numerical simulation algorithms for larger Fresnel

Probing interferometric parallax with interplanetary spacecraft

Science.gov (United States)

Rodeghiero, G.; Gini, F.; Marchili, N.; Jain, P.; Ralston, J. P.; Dallacasa, D.; Naletto, G.; Possenti, A.; Barbieri, C.; Franceschini, A.; Zampieri, L.

2017-07-01

We describe an experimental scenario for testing a novel method to measure distance and proper motion of astronomical sources. The method is based on multi-epoch observations of amplitude or intensity correlations between separate receiving systems. This technique is called Interferometric Parallax, and efficiently exploits phase information that has traditionally been overlooked. The test case we discuss combines amplitude correlations of signals from deep space interplanetary spacecraft with those from distant galactic and extragalactic radio sources with the goal of estimating the interplanetary spacecraft distance. Interferometric parallax relies on the detection of wavefront curvature effects in signals collected by pairs of separate receiving systems. The method shows promising potentialities over current techniques when the target is unresolved from the background reference sources. Developments in this field might lead to the construction of an independent, geometrical cosmic distance ladder using a dedicated project and future generation instruments. We present a conceptual overview supported by numerical estimates of its performances applied to a spacecraft orbiting the Solar System. Simulations support the feasibility of measurements with a simple and time-saving observational scheme using current facilities.

Magnonic interferometric switch for multi-valued logic circuits

Science.gov (United States)

Balynsky, Michael; Kozhevnikov, Alexander; Khivintsev, Yuri; Bhowmick, Tonmoy; Gutierrez, David; Chiang, Howard; Dudko, Galina; Filimonov, Yuri; Liu, Guanxiong; Jiang, Chenglong; Balandin, Alexander A.; Lake, Roger; Khitun, Alexander

2017-01-01

We investigated a possible use of the magnonic interferometric switches in multi-valued logic circuits. The switch is a three-terminal device consisting of two spin channels where input, control, and output signals are spin waves. Signal modulation is achieved via the interference between the source and gate spin waves. We report experimental data on a micrometer scale prototype based on the Y3Fe2(FeO4)3 structure. The output characteristics are measured at different angles of the bias magnetic field. The On/Off ratio of the prototype exceeds 13 dB at room temperature. Experimental data are complemented by the theoretical analysis and the results of micro magnetic simulations showing spin wave propagation in a micrometer size magnetic junction. We also present the results of numerical modeling illustrating the operation of a nanometer-size switch consisting of just 20 spins in the source-drain channel. The utilization of spin wave interference as a switching mechanism makes it possible to build nanometer-scale logic gates, and minimize energy per operation, which is limited only by the noise margin. The utilization of phase in addition to amplitude for information encoding offers an innovative route towards multi-state logic circuits. We describe possible implementation of the three-value logic circuits based on the magnonic interferometric switches. The advantages and shortcomings inherent in interferometric switches are also discussed.

Self Calibrating Interferometric Sensor

DEFF Research Database (Denmark)

Sørensen, Henrik Schiøtt

mask. The fabricated micro structures have been electroplated for later injection molding, showing the potential of the MIBD sensor to be mass produced with high reproducibility and sensitivity. In part three MIBD experiments on vital biological systems are described. Label–free binding studies of bio......This thesis deals with the development of an optical sensor based on micro interferometric backscatter detection (MIBD). A price effective, highly sensitive and ready for mass production platform is the goal of this project. The thesis covers three areas. The first part of the thesis deals...

A Least Square Approach for Joining Persistent Scatterer InSAR Time Series Acquired by Different Satellites

Science.gov (United States)

Caro Cuenca, Miguel; Esfahany, Sami Samiei; Hanssen, Ramon F.

2010-12-01

Persistent scatterer Radar Interferometry (PSI) can provide with a wealth of information on surface motion. These methods overcome the major limitations of the antecessor technique, interferometric SAR (InSAR), such as atmospheric disturbances, by detecting the scatterers which are slightly affected by noise. The time span that surface deformation processes are observed is limited by the satellite lifetime, which is usually less than 10 years. However most of deformation phenomena last longer. In order to fully monitor and comprehend the observed signal, acquisitions from different sensors can be merged. This is a complex task for one main reason. PSI methods provide with estimations that are relative in time to one of the acquisitions which is referred to as master or reference image. Therefore, time series acquired by different sensors will have different reference images and cannot be directly compared or joint unless they are set to the same time reference system. In global terms, the operation of translating from one to another reference systems consist of calculating a vertical offset, which is the total deformation that occurs between the two master times. To estimate this offset, different strategies can be applied, for example, using additional data such as leveling or GPS measurements. In this contribution we propose to use a least squares to merge PSI time series without any ancillary information. This method treats the time series individually, i.e. per PS, and requires some knowledge of the deformation signal, for example, if a polynomial would fairly describe the expected behavior. To test the proposed approach, we applied it to the southern Netherlands, where the surface is affected by ground water processes in abandoned mines. The time series were obtained after processing images provided by ERS1/2 and Envisat. The results were validated using in-situ water measurements, which show very high correlation with deformation time series.

Satellite SAR interferometric techniques applied to emergency mapping

Science.gov (United States)

Stefanova Vassileva, Magdalena; Riccardi, Paolo; Lecci, Daniele; Giulio Tonolo, Fabio; Boccardo Boccardo, Piero; Chiesa, Giuliana; Angeluccetti, Irene

2017-04-01

This paper aim to investigate the capabilities of the currently available SAR interferometric algorithms in the field of emergency mapping. Several tests have been performed exploiting the Copernicus Sentinel-1 data using the COTS software ENVI/SARscape 5.3. Emergency Mapping can be defined as "creation of maps, geo-information products and spatial analyses dedicated to providing situational awareness emergency management and immediate crisis information for response by means of extraction of reference (pre-event) and crisis (post-event) geographic information/data from satellite or aerial imagery". The conventional differential SAR interferometric technique (DInSAR) and the two currently available multi-temporal SAR interferometric approaches, i.e. Permanent Scatterer Interferometry (PSI) and Small BAseline Subset (SBAS), have been applied to provide crisis information useful for the emergency management activities. Depending on the considered Emergency Management phase, it may be distinguished between rapid mapping, i.e. fast provision of geospatial data regarding the area affected for the immediate emergency response, and monitoring mapping, i.e. detection of phenomena for risk prevention and mitigation activities. In order to evaluate the potential and limitations of the aforementioned SAR interferometric approaches for the specific rapid and monitoring mapping application, five main factors have been taken into account: crisis information extracted, input data required, processing time and expected accuracy. The results highlight that DInSAR has the capacity to delineate areas affected by large and sudden deformations and fulfills most of the immediate response requirements. The main limiting factor of interferometry is the availability of suitable SAR acquisition immediately after the event (e.g. Sentinel-1 mission characterized by 6-day revisiting time may not always satisfy the immediate emergency request). PSI and SBAS techniques are suitable to produce

Long-term ground deformation patterns of Bucharest using multi-temporal InSAR and multivariate dynamic analyses: a possible transpressional system?

Science.gov (United States)

Armaş, Iuliana; Mendes, Diana A.; Popa, Răzvan-Gabriel; Gheorghe, Mihaela; Popovici, Diana

2017-03-01

The aim of this exploratory research is to capture spatial evolution patterns in the Bucharest metropolitan area using sets of single polarised synthetic aperture radar (SAR) satellite data and multi-temporal radar interferometry. Three sets of SAR data acquired during the years 1992-2010 from ERS-1/-2 and ENVISAT, and 2011-2014 from TerraSAR-X satellites were used in conjunction with the Small Baseline Subset (SBAS) and persistent scatterers (PS) high-resolution multi-temporal interferometry (InSAR) techniques to provide maps of line-of-sight displacements. The satellite-based remote sensing results were combined with results derived from classical methodologies (i.e., diachronic cartography) and field research to study possible trends in developments over former clay pits, landfill excavation sites, and industrial parks. The ground displacement trend patterns were analysed using several linear and nonlinear models, and techniques. Trends based on the estimated ground displacement are characterised by long-term memory, indicated by low noise Hurst exponents, which in the long-term form interesting attractors. We hypothesize these attractors to be tectonic stress fields generated by transpressional movements.

Synthetic holography based on scanning microcavity

Directory of Open Access Journals (Sweden)

A. Di Donato

2015-11-01

Full Text Available Synthetic optical holography (SOH is an imaging technique, introduced in scanning microscopy to record amplitude and phase of a scattered field from a sample. In this paper, it is described a novel implementation of SOH through a lens-free low-coherence system, based on a scanning optical microcavity. This technique combines the low-coherence properties of the source with the mutual interference of scattered waves and the resonant behavior of a micro-cavity, in order to realize a high sensitive imaging system. Micro-cavity is compact and realized by approaching a cleaved optical fiber to the sample. The scanning system works in an open-loop configuration without the need for a reference wave, usually required in interferometric systems. Measurements were performed over calibration samples and a lateral resolution of about 1 μm is achieved by means of an optical fiber with a Numerical Aperture (NA equal to 0.1 and a Mode Field Diameter (MDF of 5.6 μm.

Super-Virtual Refraction Interferometric Redatuming: Enhancing the Refracted Energy

KAUST Repository

Aldawood, Ali

2012-02-26

onshore seismic data processing. Refraction tomography is becoming a common way to estimate an accurate near surface velocity model. One of the problems with refraction tomography is the low signal to noise ration in far offset data. To improve, we propose using super-virtual refraction interferometry to enhance the weak energy at far offsets. We use Interferometric Green\\'s functions to redatum sources by cross-correlating two traces recorded at receiver stations, A and B, from a source at location W. The result is a redatumed trace with a virtual source at A and a receiver at B, which can also be obtained by correlating two traces recorded at A and B from different shots. Stacking them would enhance the signal-to-noise ratio of this "virtual" trace. We next augment redatuming with convolution and stacking. The trace recorded at B from a virtual source at A is convolved with the original trace recorded at A from a source at W. The result is a "super-virtual" trace at B in the far-offset from a source at W. Stacking N traces gives a vN-improvement. We applied our method to noisy synthetic and field data recorded over a complex near-surface and we could pick more traces at far offsets. It was possible to accommodate more picks resulting in a better subsurface coverage

Super-Virtual Refraction Interferometric Redatuming: Enhancing the Refracted Energy

KAUST Repository

Aldawood, Ali; Alshuhail, Abdulrahman Abdullatif Abdulrahman; Hanafy, Sherif

2012-01-01

onshore seismic data processing. Refraction tomography is becoming a common way to estimate an accurate near surface velocity model. One of the problems with refraction tomography is the low signal to noise ration in far offset data. To improve, we propose using super-virtual refraction interferometry to enhance the weak energy at far offsets. We use Interferometric Green's functions to redatum sources by cross-correlating two traces recorded at receiver stations, A and B, from a source at location W. The result is a redatumed trace with a virtual source at A and a receiver at B, which can also be obtained by correlating two traces recorded at A and B from different shots. Stacking them would enhance the signal-to-noise ratio of this "virtual" trace. We next augment redatuming with convolution and stacking. The trace recorded at B from a virtual source at A is convolved with the original trace recorded at A from a source at W. The result is a "super-virtual" trace at B in the far-offset from a source at W. Stacking N traces gives a vN-improvement. We applied our method to noisy synthetic and field data recorded over a complex near-surface and we could pick more traces at far offsets. It was possible to accommodate more picks resulting in a better subsurface coverage

Automated data reduction for optical interferometric data

International Nuclear Information System (INIS)

Boyd, R.D.; Miller, D.J.; Ghiglia, D.C.

1983-01-01

The potential for significant progress in understanding many transport processes exists through the use of a rapid and automated data reduction process of optical interferometric data. An example involving natural convection in a horizontal annulus is used to demonstrate that the accuracy possible in automated techniques is better than 99.0%

Interferometric full-waveform inversion of time-lapse data

KAUST Repository

Sinha, Mrinal

2017-01-01

surveys. To overcome this challenge, we propose the use of interferometric full waveform inversion (IFWI) for inverting the velocity model from data recorded by baseline and monitor surveys. A known reflector is used as the reference reflector for IFWI

YSAR: a compact low-cost synthetic aperture radar

Science.gov (United States)

Thompson, Douglas G.; Arnold, David V.; Long, David G.; Miner, Gayle F.; Karlinsey, Thomas W.; Robertson, Adam E.

1997-09-01

The Brigham Young University Synthetic Aperture Radar (YSAR) is a compact, inexpensive SAR system which can be flown on a small aircraft. The system has exhibited a resolution of approximately 0.8 m by 0.8 m in test flights in calm conditions. YSAR has been used to collect data over archeological sites in Israel. Using a relatively low frequency (2.1 GHz), we hope to be able to identify walls or other archeological features to assist in excavation. A large data set of radar and photographic data have been collected over sites at Tel Safi, Qumran, Tel Micnah, and the Zippori National Forest in Israel. We show sample images from the archeological data. We are currently working on improved autofocus algorithms for this data and are developing a small, low-cost interferometric SAR system (YINSAR) for operation from a small aircraft.

Size-selective detection in integrated optical interferometric biosensors

NARCIS (Netherlands)

Mulder, Harmen K P; Ymeti, Aurel; Subramaniam, Vinod; Kanger, Johannes S

2012-01-01

We present a new size-selective detection method for integrated optical interferometric biosensors that can strongly enhance their performance. We demonstrate that by launching multiple wavelengths into a Young interferometer waveguide sensor it is feasible to derive refractive index changes from

Interferometric interrogation of π-phase shifted fiber Bragg grating sensors

Science.gov (United States)

Srivastava, Deepa; Tiwari, Umesh; Das, Bhargab

2018-03-01

Interferometric interrogation technique realized for conventional fiber Bragg grating (FBG) sensors is historically known to offer the highest sensitivity measurements, however, it has not been yet explored for π-phase-shifted FBG (πFBG) sensors. This, we believe, is due to the complex nature of the reflection/transmission spectrum of a πFBG, which cannot be directly used for interferometric interrogation purpose. Therefore, we propose here an innovative as well as simple concept towards this direction, wherein, the transmission spectrum of a πFBG sensor is optically filtered using a specially designed fiber grating. The resulting filtered spectrum retains the entire characteristics of a πFBG sensor and hence the filtered spectrum can be interrogated with interferometric principles. Furthermore, due to the extremely narrow transmission notch of a πFBG sensor, a fiber interferometer can be realized with significantly longer path difference. This leads to substantially enhanced detection limit as compared to sensors based on a regular FBG of similar length. Theoretical analysis demonstrates that high resolution weak dynamic strain measurement down to 4 pε /√{ Hz } is easily achievable. Preliminary experimental results are also presented as proof-of-concept of the proposed interrogation principle.

Interferometric Imaging Directly with Closure Phases and Closure Amplitudes

Science.gov (United States)

Chael, Andrew A.; Johnson, Michael D.; Bouman, Katherine L.; Blackburn, Lindy L.; Akiyama, Kazunori; Narayan, Ramesh

2018-04-01

Interferometric imaging now achieves angular resolutions as fine as ∼10 μas, probing scales that are inaccessible to single telescopes. Traditional synthesis imaging methods require calibrated visibilities; however, interferometric calibration is challenging, especially at high frequencies. Nevertheless, most studies present only a single image of their data after a process of “self-calibration,” an iterative procedure where the initial image and calibration assumptions can significantly influence the final image. We present a method for efficient interferometric imaging directly using only closure amplitudes and closure phases, which are immune to station-based calibration errors. Closure-only imaging provides results that are as noncommittal as possible and allows for reconstructing an image independently from separate amplitude and phase self-calibration. While closure-only imaging eliminates some image information (e.g., the total image flux density and the image centroid), this information can be recovered through a small number of additional constraints. We demonstrate that closure-only imaging can produce high-fidelity results, even for sparse arrays such as the Event Horizon Telescope, and that the resulting images are independent of the level of systematic amplitude error. We apply closure imaging to VLBA and ALMA data and show that it is capable of matching or exceeding the performance of traditional self-calibration and CLEAN for these data sets.

High-Level Performance Modeling of SAR Systems

Science.gov (United States)

Chen, Curtis

2006-01-01

SAUSAGE (Still Another Utility for SAR Analysis that s General and Extensible) is a computer program for modeling (see figure) the performance of synthetic- aperture radar (SAR) or interferometric synthetic-aperture radar (InSAR or IFSAR) systems. The user is assumed to be familiar with the basic principles of SAR imaging and interferometry. Given design parameters (e.g., altitude, power, and bandwidth) that characterize a radar system, the software predicts various performance metrics (e.g., signal-to-noise ratio and resolution). SAUSAGE is intended to be a general software tool for quick, high-level evaluation of radar designs; it is not meant to capture all the subtleties, nuances, and particulars of specific systems. SAUSAGE was written to facilitate the exploration of engineering tradeoffs within the multidimensional space of design parameters. Typically, this space is examined through an iterative process of adjusting the values of the design parameters and examining the effects of the adjustments on the overall performance of the system at each iteration. The software is designed to be modular and extensible to enable consideration of a variety of operating modes and antenna beam patterns, including, for example, strip-map and spotlight SAR acquisitions, polarimetry, burst modes, and squinted geometries.

Distribution of creep in the northern San Francisco Bay Area illuminated by repeating earthquakes and InSAR

Science.gov (United States)

Funning, G.; Shakibay Senobari, N.; Swiatlowski, J. L.

2017-12-01

Surface observations of fault creep in the region north of San Francisco Bay are sporadic. While there are long-standing instances of creep-affected infrastructure on the Maacama and Bartlett Springs faults, the lateral and depth extents of creep on these and other faults in the region remain a question. Here, we supplement this sparse existing observation set with additional information from repeating earthquake sequences (REs) and InSAR, to illuminate, and significantly improve our knowledge of, creep across the region. Repeating earthquakes have long been considered indicators of creep on faults. We present the results of an extensive similarity search through over 600,000 archived waveforms from 43,000 events using a fast algorithm; from this we can identify 39 periodic repeating sequences and over 80 nonperiodic repeated event groups. We compare these with decadal line-of-sight velocity measurements made by applying the StaMPS time series InSAR code to ERS and Envisat data covering the region, that can be used to identify surface creep on faults. On the Rodgers Creek, Maacama and Bartlett Springs faults, both InSAR and REs show corroborating evidence for creep at locations where it was previously inferred. The REs additionally provide information on its depth extent. On the Maacama fault, we find REs extending almost to the southern limit of the mapped fault trace, south of Cloverdale, suggesting that creep may be pervasive on the fault. We can also identify structural complexity both in the stepover region with the Rodgers Creek fault, and in the northern segment of the fault close to Willits, potentially indicating parallel and/or down-dip branching creeping structures in both locations. REs on the Bartlett Springs fault indicate creep that extends across the full down-dip width of the brittle fault; here the proximity of InSAR creep rate estimates and a shallow RE sequence may permit a calibration of the RE `creepmeter', allowing us to estimate creep rates

Light-pulse atom interferometric device

Science.gov (United States)

Biedermann, Grant; McGuinness, Hayden James Evans; Rakholia, Akash; Jau, Yuan-Yu; Schwindt, Peter; Wheeler, David R.

2016-03-22

An atomic interferometric device useful, e.g., for measuring acceleration or rotation is provided. The device comprises at least one vapor cell containing a Raman-active chemical species, an optical system, and at least one detector. The optical system is conformed to implement a Raman pulse interferometer in which Raman transitions are stimulated in a warm vapor of the Raman-active chemical species. The detector is conformed to detect changes in the populations of different internal states of atoms that have been irradiated by the optical system.

Atom interferometric gravity gradiometer: Disturbance compensation and mobile gradiometry

Science.gov (United States)

Mahadeswaraswamy, Chetan

First ever mobile gravity gradient measurement based on Atom Interferometric sensors has been demonstrated. Mobile gravity gradiometers play a significant role in high accuracy inertial navigation systems in order to distinguish inertial acceleration and acceleration due to gravity. The gravity gradiometer consists of two atom interferometric accelerometers. In each of the accelerometer an ensemble of laser cooled Cesium atoms is dropped and using counter propagating Raman pulses (pi/2-pi-pi/2) the ensemble is split into two states for carrying out atom interferometry. The interferometer phase is proportional to the specific force experienced by the atoms which is a combination of inertial acceleration and acceleration due to gravity. The difference in phase between the two atom interferometric sensors is proportional to gravity gradient if the platform does not undergo any rotational motion. However, any rotational motion of the platform induces spurious gravity gradient measurements. This apparent gravity gradient due to platform rotation is considerably different for an atom interferometric sensor compared to a conventional force rebalance type sensor. The atoms are in free fall and are not influenced by the motion of the case except at the instants of Raman pulses. A model for determining apparent gravity gradient due to rotation of platform was developed and experimentally verified for different frequencies. This transfer function measurement also lead to the development of a new technique for aligning the Raman laser beams with the atom clusters to within 20 mu rad. This gravity gradiometer is situated in a truck for the purpose of undertaking mobile surveys. A disturbance compensation system was designed and built in order to compensate for the rotational disturbances experienced on the floor of a truck. An electric drive system was also designed specifically to be able to move the truck in a uniform motion at very low speeds of about 1cm/s. A 250 x10-9 s-2

Nanohertz gravitational wave searches with interferometric pulsar timing experiments.

Science.gov (United States)

Tinto, Massimo

2011-05-13

We estimate the sensitivity to nano-Hertz gravitational waves of pulsar timing experiments in which two highly stable millisecond pulsars are tracked simultaneously with two neighboring radio telescopes that are referenced to the same timekeeping subsystem (i.e., "the clock"). By taking the difference of the two time-of-arrival residual data streams we can exactly cancel the clock noise in the combined data set, thereby enhancing the sensitivity to gravitational waves. We estimate that, in the band (10(-9)-10(-8))  Hz, this "interferometric" pulsar timing technique can potentially improve the sensitivity to gravitational radiation by almost 2 orders of magnitude over that of single-telescopes. Interferometric pulsar timing experiments could be performed with neighboring pairs of antennas of the NASA's Deep Space Network and the forthcoming large arraying projects.

Low-cost interferometric TDM technology for dynamic sensing applications

Science.gov (United States)

Bush, Jeff; Cekorich, Allen

2004-12-01

A low-cost design approach for Time Division Multiplexed (TDM) fiber-optic interferometric interrogation of multi-channel sensor arrays is presented. This paper describes the evolutionary design process of the subject design. First, the requisite elements of interferometric interrogation are defined for a single channel sensor. The concept is then extended to multi-channel sensor interrogation implementing a TDM multiplex scheme where "traditional" design elements are utilized. The cost of the traditional TDM interrogator is investigated and concluded to be too high for entry into many markets. A new design approach is presented which significantly reduces the cost for TDM interrogation. This new approach, in accordance with the cost objectives, shows promise to bring this technology to within the threshold of commercial acceptance for a wide range of distributed fiber sensing applications.

Surface Deformation Observed by InSAR due to Fluid Injection: a Test Study in the Central U.S.

Science.gov (United States)

Deng, F.; Dixon, T. H.

2017-12-01

The central and eastern U.S. has undergone a dramatic increase in seismicity over the past few years. Many of these recent earthquakes were likely induced by human activities, with underground fluid injection for oil and gas extraction being one of the main contributors. Surface deformation caused by fluid injection has been captured by GPS and InSAR observations in several areas. For example, surface uplift of up to 10 cm due to CO2 injection between 2007 and 2011 was measured by InSAR at an enhanced oil recovery site in west Texas. We are using Texas and Oklahoma as test areas to analyze the potential relationship between surface deformation, underground fluid injection and induced earthquakes. C-band SAR data from ENVISAT and Sentinel-1, and L-band SAR data from ALOS and ALOS-2 are used to form decade-long time series. Based on the surface deformation derived from the time series InSAR data, subsurface volume change and volumetric strain in an elastic half space are estimated. Seismic data provided by the USGS are used to analyze the spatial and temporal distribution pattern of earthquakes, and the potential link between surface deformation and induced earthquakes. The trigger mechanism will be combined with forward modeling to predict seismicity and assess related hazard for future study.

DETECTION OF FAST TRANSIENTS WITH RADIO INTERFEROMETRIC ARRAYS

International Nuclear Information System (INIS)

Bhat, N. D. R.; Chengalur, J. N.; Gupta, Y.; Prasad, J.; Roy, J.; Kudale, S. S.; Cox, P. J.; Bailes, M.; Burke-Spolaor, S.; Van Straten, W.

2013-01-01

Next-generation radio arrays, including the Square Kilometre Array (SKA) and its pathfinders, will open up new avenues for exciting transient science at radio wavelengths. Their innovative designs, comprising a large number of small elements, pose several challenges in digital processing and optimal observing strategies. The Giant Metre-wave Radio Telescope (GMRT) presents an excellent test-bed for developing and validating suitable observing modes and strategies for transient experiments with future arrays. Here we describe the first phase of the ongoing development of a transient detection system for GMRT that is planned to eventually function in a commensal mode with other observing programs. It capitalizes on the GMRT's interferometric and sub-array capabilities, and the versatility of a new software backend. We outline considerations in the plan and design of transient exploration programs with interferometric arrays, and describe a pilot survey that was undertaken to aid in the development of algorithms and associated analysis software. This survey was conducted at 325 and 610 MHz, and covered 360 deg 2 of the sky with short dwell times. It provides large volumes of real data that can be used to test the efficacies of various algorithms and observing strategies applicable for transient detection. We present examples that illustrate the methodologies of detecting short-duration transients, including the use of sub-arrays for higher resilience to spurious events of terrestrial origin, localization of candidate events via imaging, and the use of a phased array for improved signal detection and confirmation. In addition to demonstrating applications of interferometric arrays for fast transient exploration, our efforts mark important steps in the roadmap toward SKA-era science.

Detection of Fast Transients with Radio Interferometric Arrays

Science.gov (United States)

Bhat, N. D. R.; Chengalur, J. N.; Cox, P. J.; Gupta, Y.; Prasad, J.; Roy, J.; Bailes, M.; Burke-Spolaor, S.; Kudale, S. S.; van Straten, W.

2013-05-01

Next-generation radio arrays, including the Square Kilometre Array (SKA) and its pathfinders, will open up new avenues for exciting transient science at radio wavelengths. Their innovative designs, comprising a large number of small elements, pose several challenges in digital processing and optimal observing strategies. The Giant Metre-wave Radio Telescope (GMRT) presents an excellent test-bed for developing and validating suitable observing modes and strategies for transient experiments with future arrays. Here we describe the first phase of the ongoing development of a transient detection system for GMRT that is planned to eventually function in a commensal mode with other observing programs. It capitalizes on the GMRT's interferometric and sub-array capabilities, and the versatility of a new software backend. We outline considerations in the plan and design of transient exploration programs with interferometric arrays, and describe a pilot survey that was undertaken to aid in the development of algorithms and associated analysis software. This survey was conducted at 325 and 610 MHz, and covered 360 deg2 of the sky with short dwell times. It provides large volumes of real data that can be used to test the efficacies of various algorithms and observing strategies applicable for transient detection. We present examples that illustrate the methodologies of detecting short-duration transients, including the use of sub-arrays for higher resilience to spurious events of terrestrial origin, localization of candidate events via imaging, and the use of a phased array for improved signal detection and confirmation. In addition to demonstrating applications of interferometric arrays for fast transient exploration, our efforts mark important steps in the roadmap toward SKA-era science.

Rapid interferometric imaging of printed drug laden multilayer structures

DEFF Research Database (Denmark)

Sandler, Niklas; Kassamakov, Ivan; Ehlers, Henrik

2014-01-01

The developments in printing technologies allow fabrication of micron-size nano-layered delivery systems to personal specifications. In this study we fabricated layered polymer structures for drug-delivery into a microfluidic channel and aimed to interferometrically assure their topography...

Integrated satellite InSAR and slope stability modeling to support hazard assessment at the Safuna Alta glacial lake, Peru

Science.gov (United States)

Cochachin, Alejo; Frey, Holger; Huggel, Christian; Strozzi, Tazio; Büechi, Emanuel; Cui, Fanpeng; Flores, Andrés; Saito, Carlos

2017-04-01

The Safuna glacial lakes (77˚ 37' W, 08˚ 50' S) are located in the headwater of the Tayapampa catchment, in the northernmost part of the Cordillera Blanca, Peru. The upper lake, Laguna Safuna Alta at 4354 m asl has formed in the 1960s behind a terminal moraine of the retreating Pucajirca Glacier, named after the peak south of the lakes. Safuna Alta currently has a volume of 15 x 106 m3. In 2002 a rock fall of several million m3 from the proximal left lateral moraine hit the Safuna Alta lake and triggered an impact wave which overtopped the moraine dam and passed into the lower lake, Laguna Safuna Baja, which absorbed most of the outburst flood from the upper lake, but nevertheless causing loss in cattle, degradation of agricultural land downstream and damages to a hydroelectric power station in Quitaracsa gorge. Event reconstructions showed that the impact wave in the Safuna Alta lake had a runup height of 100 m or more, and weakened the moraine dam of Safuna Alta. This fact, in combination with the large lake volumes and the continued possibility for landslides from the left proximal moraine pose a considerable risk for the downstream settlements as well as the recently completed Quitaracsa hydroelectric power plant. In the framework of a project funded by the European Space Agency (ESA), the hazard situation at the Safuna Alta lake is assessed by a combination of satellite radar data analysis, field investigations, and slope stability modeling. Interferometric analyses of the Synthetic Aperture Radar (InSAR) of ALOS-1 Palsar-1, ALOS-2 Palsar-2 and Sentinel-1 data from 2016 reveal terrain displacements of 2 cm y-1 in the detachment zone of the 2002 rock avalanche. More detailed insights into the characteristics of these terrain deformations are gained by repeat surveys with differential GPS (DGPS) and tachymetric measurements. A drone flight provides the information for the generation of a high-resolution digital elevation model (DEM), which is used for the

InSAR detection of aquifer recovery: Case studies of Koehn Lake (central California) and Lone Tree Gold Mine (Basin and Range)

Science.gov (United States)

Wdowinski, S.; Greene, F.; Amelung, F.

2013-12-01

Anthropogenic intervention in groundwater flow and aquifer storage often results in vertical movements of Earth's surface, which are well detected by InSAR observations. Most anthropogenic intervention occurs due to groundwater extraction for both agriculture and human consumption and results in land subsidence. However in some cases, ending anthropogenic intervention can lead to aquifer recovery and, consequently, surface uplift. In this study we present two such cases of aquifer recovery. The first case is the aquifer beneath Koehn Lake in Central California, which was overused to meet agricultural demands until the 1990's. The second case is the Lone Tree Gold Mine in Nevada that during active mining in the 1991-2006 groundwater pumping disrupted the aquifer and cause subsidence. But after mining ceased, groundwater flow was recovered and resulted in uplift. In both cases we studied the surface uplift using InSAR time series observations. We conduct an ERS and Envisat InSAR survey over Koehn Lake in California and Lone Tree Gold Mine in Nevada between 1992 and 2010. We followed the SBAS algorithm to generate a time-series of ground displacements and average velocities of pixels, which remain coherent through time in the SAR dataset. A total of 100 and 80 combined ERS and Envisat SAR dates are inverted for Koehn Lake and Lone Tree Gold Mine respectively. Results for the Koehn Lake area indicate a rapid uplift of about 3.5 mm/yr between 1992-2000 and a slower uplift rate of 1.6 mm/yr between 2000-2004, suggesting a decrease in the recovery process. The observed uplift correlates well with groundwater level increase in the Koehn Lake area. Results for the Lone Tree Gold Mine show a constant subsidence (~ 1 cm/yr) due to groundwater extraction between 1992-2006, but uplift of ~1 cm/yr since the beginning of 2007. In both case studies, InSAR observations reveal that the aquifer recovery is accompanied by surface uplift. We plan to use the InSAR observations and the

Multi-temporal InSAR Datastacks for Surface Deformation Monitoring: a Review

Science.gov (United States)

Ferretti, A.; Novali, F.; Prati, C.; Rocca, F.

2009-04-01

In the last decade extensive processing of thousands of satellite radar scenes acquired by different sensors (e.g. ERS-1/2, ENVISAT and RADARSAT) has demonstrated how multi-temporal data-sets can be successfully exploited for surface deformation monitoring, by identifying objects on the terrain that have a stable, point-like behaviour. These objects, referred to as Permanent or Persistent Scatterers (PS), can be geo-coded and monitored for movement very accurately, acting as a "natural" geodetic network, integrating successfully continuous GPS data. After a brief analysis of both advantages and drawbacks of InSAR datastacks, the paper presents examples of applications of PS measurements for detecting and monitoring active faults, aquifers and oil/gas reservoirs, using experience in Europe, North America and Japan, and concludes with a discussion on future directions for PSInSAR analysis. Special attention is paid to the possibility of creating deformation maps over wide areas using historical archives of data already available. This second part of the paper will briefly discuss the technical features of the new radar sensors recently launched (namely: TerraSAR-X, RADARSAT-2, and CosmoSkyMed) and their impact on space geodesy, highlighting the importance of data continuity and standardized acquisition policies for almost all InSAR and PSInSAR applications. Finally, recent advances in the algorithms applied in PS analysis, such as detection of "temporary PS", PS characterization and exploitation of distributed scatterers, will be briefly discussed based on the processing of real data.

Finite source modelling of magmatic unrest in Socorro, New Mexico, and Long Valley, California

Science.gov (United States)

Fialko, Yuri; Simons, Mark; Khazan, Yakov

2001-07-01

We investigate surface deformation associated with currently active crustal magma bodies in Socorro, New Mexico, and Long Valley, California, USA. We invert available geodetic data from these locations to constrain the overall geometry and dynamics of the inferred deformation sources at depth. Our best-fitting model for the Socorro magma body is a sill with a depth of 19km, an effective diameter of 70km and a rate of increase in the excess magma pressure of 0.6kPayr-1. We show that the corresponding volumetric inflation rate is ~6×10-3km3yr-1, which is considerably less than previously suggested. The measured inflation rate of the Socorro magma body may result from a steady influx of magma from a deep source, or a volume increase associated with melting of the magma chamber roof (i.e. crustal anatexis). In the latter case, the most recent major injection of mantle-derived melts into the middle crust beneath Socorro may have occurred within the last several tens to several hundreds of years. The Synthetic Interferometric Aperture Radar (InSAR) data collected in the area of the Long Valley caldera, CA, between June 1996 and July 1998 reveal an intracaldera uplift with a maximum amplitude of ~11cm and a volume of 3.5×10-2km3. Modelling of the InSAR data suggests that the observed deformation might be due to either a sill-like magma body at a depth of ~12km or a pluton-like magma body at a depth of ~8km beneath the resurgent dome. Assuming that the caldera fill deforms as an isotropic linear elastic solid, a joint inversion of the InSAR data and two-colour laser geodimeter data (which provide independent constraints on horizontal displacements at the surface) suggests that the inferred magma chamber is a steeply dipping prolate spheroid with a depth of 7-9km and an aspect ratio in excess of 2:1. Our results highlight the need for large radar look angles and multiple look directions in future InSAR missions.

Volcanic and Tectonic Activity in the Red Sea Region (2004-2013): Insights from Satellite Radar Interferometry and Optical Imagery

KAUST Repository

Xu, Wenbin

2015-04-01

Studying recent volcanic and tectonic events in the Red Sea region is important for improving our knowledge of the Red Sea plate boundary and for regional geohazard assessments. However, limited information has been available about the past activity due to insufficient in-situ data and remoteness of some of the activity. In this dissertation, I have used satellite remote sensing to derive new information about several recent volcanic and tectonic events in the Red Sea region. I first report on three volcanic eruptions in the southern Red Sea, the 2007-8 Jebel at Tair eruption and the 2011-12 & 2013 Zubair eruptions, which resulted in formation of two new islands. Series of high- resolution optical images were used to map the extent of lava flows and to observe and analyze the growth and destructive processes of the new islands. I used Interferometric Synthetic Aperture Radar (InSAR) data to study the evolution of lava flows, to estimate their volumes, as well as to generate ground displacements maps, which were used to model the dikes that fed the eruptions. I then report on my work of the 2009 Harrat Lunayyir dike intrusion and the 2004 Tabuk earthquake sequence in western Saudi Arabia. I used InSAR observations and stress calculations to study the intruding dike at Harrat Lunayyir, while I combined InSAR data and Bayesian estimation to study the Tabuk earthquake activity. The key findings of the thesis are: 1) The recent volcanic eruptions in the southern Red Sea indicate that the area is magmatically more active than previously acknowledged and that a rifting episode has been taken place in the southern Red Sea; 2) Stress interactions between an ascending dike intrusion and normal faulting on graben-bounding faults above the dike can inhibit vertical propagation of magma towards the surface; 3) InSAR observations can improve locations of shallow earthquakes and fault model uncertainties are useful to associate earthquake activity with mapped faults; 4). The

Assessment of Snow Status Changes Using L-HH Temporal-Coherence Components at Mt. Dagu, China

Directory of Open Access Journals (Sweden)

Yong Wang

2015-09-01

Full Text Available Multitemporal Phased Array type L-band Synthetic Aperture Radar (PALSAR horizontally transmitted and horizontally received (HH coherence data was decomposed into temporal-coherence, spatial-coherence, and thermal noise components. The multitemporal data spanned between February and May of 2008, and consisted of two pairs of interferometric SAR (InSAR images formed by consecutive repeat passes. With the analysis of ancillary data, a snow increase process and a snow decrease process were determined. Then, the multiple temporal-coherence components were used to study the variation of thawing and freezing statuses of snow because the components can mostly reflect the temporal change of the snow that occurred between two data acquisitions. Compared with snow mapping results derived from optical images, the outcomes from the snow increase process and the snow decrease process reached an overall accuracy of 71.3% and 79.5%, respectively. Being capable of delineating not only the areas with or without snow cover but also status changes among no-snow, wet snow, and dry snow, we have developed a critical means to assess the water resource in alpine areas.

The 2015 Wolf volcano (Galápagos) eruption studied using Sentinel-1 and ALOS-2 data

KAUST Repository

Xu, Wenbin; Jonsson, Sigurjon; Ruch, Joel; Aoki, Yosuke

2016-01-01

An energetic eruption started on 25 May 2015 from a circumferential fissure at the summit of Wolf volcano on Isabela Island, western Galápagos. Further eruptive activity within the Wolf caldera followed in mid-June 2015. As no geodetic observations of earlier eruptions at Wolf exist, this eruption provides an opportunity to study the volcano's magmatic plumbing system for the first time. Here we use interferometric synthetic aperture radar (InSAR) data from both the Sentinel-1A and ALOS-2 satellites to map and analyze the surface deformation at four time periods during the activity. These data allow us to identify the two eruption phases and reveal strong coeruptive subsidence within the Wolf caldera that is superimposed on a larger volcano-wide subsidence signal. Modeling of the surface displacements shows that two shallow magma reservoirs located under Wolf at ~1 km and ~5 km below sea level explain the subsidence and that these reservoirs appear to be hydraulically connected. We also suggest that the transition from the circumferential to the intracaldera eruption may have involved ring fault activity.

Ionospheric errors compensation for ground deformation estimation with new generation SAR

Science.gov (United States)

Gomba, Giorgio; De Zan, Francesco; Rodriguez Gonzalez, Fernando

2017-04-01

Synthetic aperture radar (SAR) and interferometric SAR (InSAR) measurements are disturbed by the propagation velocity changes of microwaves that are caused by the high density of free electrons in the ionosphere. Most affected are low-frequency (L- or P-band) radars, as the recently launched ALOS-2 and the future Tandem-L and NISAR, although higher frequency (C- or X-band) systems, as the recently launched Sentinel-1, are not immune. Since the ionosphere is an obstacle to increasing the precision of new generation SAR systems needed to remotely measure the Earth's dynamic processes as for example ground deformation, it is necessary to estimate and compensate ionospheric propagation delays in SAR signals. In this work we discuss about the influence of the ionosphere on interferograms and the possible correction methods with relative accuracies. Consequently, the effect of ionospheric induced errors on ground deformation measurements prior and after ionosphere compensation will be analyzed. Examples will be presented of corrupted measurements of earthquakes and fault motion along with the corrected results using different methods.

The 2015 Wolf volcano (Galápagos) eruption studied using Sentinel-1 and ALOS-2 data

KAUST Repository

Xu, Wenbin

2016-09-28

An energetic eruption started on 25 May 2015 from a circumferential fissure at the summit of Wolf volcano on Isabela Island, western Galápagos. Further eruptive activity within the Wolf caldera followed in mid-June 2015. As no geodetic observations of earlier eruptions at Wolf exist, this eruption provides an opportunity to study the volcano\\'s magmatic plumbing system for the first time. Here we use interferometric synthetic aperture radar (InSAR) data from both the Sentinel-1A and ALOS-2 satellites to map and analyze the surface deformation at four time periods during the activity. These data allow us to identify the two eruption phases and reveal strong coeruptive subsidence within the Wolf caldera that is superimposed on a larger volcano-wide subsidence signal. Modeling of the surface displacements shows that two shallow magma reservoirs located under Wolf at ~1 km and ~5 km below sea level explain the subsidence and that these reservoirs appear to be hydraulically connected. We also suggest that the transition from the circumferential to the intracaldera eruption may have involved ring fault activity.

Coseismic Slip Deficit of the 2017 Mw 6.5 Ormoc Earthquake That Occurred Along a Creeping Segment and Geothermal Field of the Philippine Fault

Science.gov (United States)

Yang, Ying-Hui; Tsai, Min-Chien; Hu, Jyr-Ching; Aurelio, Mario A.; Hashimoto, Manabu; Escudero, John Agustin P.; Su, Zhe; Chen, Qiang

2018-03-01

Coseismic surface deformation imaged through interferometric synthetic aperture radar (InSAR) measurements was used to estimate the fault geometry and slip distribution of the 2017 Mw 6.5 Ormoc earthquake along a creeping segment of the Philippine Fault on Leyte Island. Our best fitting faulting model suggests that the coseismic rupture occurred on a fault plane with high dip angle of 78.5° and strike angle of 325.8°, and the estimated maximum fault slip of 2.3 m is located at 6.5 km east-northeast of the town of Kananga. The recognized insignificant slip in the Tongonan geothermal field zone implies that the plastic behavior caused by high geothermal gradient underneath the Tongonan geothermal field could prevent the coseismic failure in heated rock mass in this zone. The predicted Coulomb failure stress change shows that a significant positive Coulomb failure stress change occurred along the SE segment of central Philippine Fault with insignificant coseismic slip and infrequent aftershocks, which suggests an increasing risk for future seismic hazard.

Identification of active release planes using ground-based differential InSAR at the Randa rock slope instability, Switzerland

Directory of Open Access Journals (Sweden)

V. Gischig

2009-12-01

Full Text Available Five ground-based differential interferometric synthetic aperture radar (GB-DInSAR surveys were conducted between 2005 and 2007 at the rock slope instability at Randa, Switzerland. Resultant displacement maps revealed, for the first time, the presence of an active basal rupture zone and a lateral release surface daylighting on the exposed 1991 failure scarp. Structures correlated with the boundaries of interferometric displacement domains were confirmed using a helicopter-based LiDAR DTM and oblique aerial photography. Former investigations at the site failed to conclusively detect these active release surfaces essential for kinematic and hazard analysis of the instability, although their existence had been hypothesized. The determination of the basal and lateral release planes also allowed a more accurate estimate of the currently unstable volume of 5.7±1.5 million m³. The displacement patterns reveal that two different kinematic behaviors dominate the instability, i.e. toppling above 2200 m and translational failure below. In the toppling part of the instability the areas with the highest GB-DInSAR displacements correspond to areas of enhanced micro-seismic activity. The observation of only few strongly active discontinuities daylighting on the 1991 failure surface points to a rather uniform movement in the lower portion of the instability, while most of the slip occurs along the basal rupture plane. Comparison of GB-DInSAR displacements with mapped discontinuities revealed correlations between displacement patterns and active structures, although spatial offsets occur as a result of the effective resolution of GB-DInSAR. Similarly, comparisons with measurements from total station surveys generally showed good agreement. Discrepancies arose in several cases due to local movement of blocks, the size of which could not be resolved using GB-DInSAR.

Improving the performance of interferometric imaging through the use of disturbance feedforward.

Science.gov (United States)

Böhm, Michael; Glück, Martin; Keck, Alexander; Pott, Jörg-Uwe; Sawodny, Oliver

2017-05-01

In this paper, we present a disturbance compensation technique to improve the performance of interferometric imaging for extremely large ground-based telescopes, e.g., the Large Binocular Telescope (LBT), which serves as the application example in this contribution. The most significant disturbance sources at ground-based telescopes are wind-induced mechanical vibrations in the range of 8-60 Hz. Traditionally, their optical effect is eliminated by feedback systems, such as the adaptive optics control loop combined with a fringe tracking system within the interferometric instrument. In this paper, accelerometers are used to measure the vibrations. These measurements are used to estimate the motion of the mirrors, i.e., tip, tilt and piston, with a dynamic estimator. Additional delay compensation methods are presented to cancel sensor network delays and actuator input delays, improving the estimation result even more, particularly at higher frequencies. Because various instruments benefit from the implementation of telescope vibration mitigation, the estimator is implemented as a separate, independent software on the telescope, publishing the estimated values via multicast on the telescope's ethernet. Every client capable of using and correcting the estimated disturbances can subscribe and use these values in a feedforward for its compensation device, e.g., the deformable mirror, the piston mirror of LINC-NIRVANA, or the fast path length corrector of the Large Binocular Telescope Interferometer. This easy-to-use approach eventually leveraged the presented technology for interferometric use at the LBT and now significantly improves the sky coverage, performance, and operational robustness of interferometric imaging on a regular basis.

Investigation of organic light emitting diodes for interferometric purposes

Science.gov (United States)

Pakula, Anna; Zimak, Marzena; Sałbut, Leszek

2011-05-01

Recently the new type of light source has been introduced to the market. Organic light emitting diode (OLED) is not only interesting because of the low applying voltage, wide light emitting areas and emission efficiency. It gives the possibility to create a light source of a various shape, various color and in the near future very likely even the one that will change shape and spectrum in time in controlled way. Those opportunities have not been in our reach until now. In the paper authors try to give an answer to the question if the new light source -OLED - is suitable for interferometric purposes. Tests cover the short and long term spectrum stability, spectrum changes due to the emission area selection. In the paper the results of two OLEDs (red and white) are shown together with the result of an attempt to use them in an interferometric setup.

Landslide precursory deformation interpretation using ALOS-2/PALSAR-2 InSAR image along Min River in Maoxien, Sichuan Province, China

Science.gov (United States)

Sato, H. P.

2017-12-01

Maoxien area in Sichuan Province, China has many landslide. For example, landslide (rock avalanche) occurred on the slope in Xinmocun Village in Maoxeien on 24 June 2017. I produced and interpreetd InSAR image using ALOS/PALSAR data observed on 19 Jul 2007-3 Sep 2007 and on 27 Jan 2011-14 Mar 2011, and ALOS-2/PALSAR-2 data observed on 26 Jul 2015-13 Dec 2015 and on 13 Dec 2015-11 Dec 2016. These images give good coherence and it was easy to identify local landslide surface deformation. As a result, e.g., two slopes were estimated to have local landslide surface deformation; one is at 103.936587 deg E and 32.04462 deg N, another is at 103.674754 deg E and 31.852838 N. However, the slope in Xinmocun Village was not identified as landslide precursory deformation. In the poster I will present more InSAR image observed after 11 Dec 2016 and discuss the possibility of local landslide surface deformaton using InSAR image. ALOS/PALSAR and ALOS-2/PALSAR-2 data were provided by JAXA through Landslide Working Group in JAXA and through Special Research 2015-B-02 of Earthquake Research Institute/Tokyo University. This study was supported by KAKENHI (17H02973).

Groundwater depletion in Central Mexico: Use of GRACE and InSAR to support water resources management

Science.gov (United States)

Castellazzi, Pascal; Martel, Richard; Rivera, Alfonso; Huang, Jianliang; Pavlic, Goran; Calderhead, Angus I.; Chaussard, Estelle; Garfias, Jaime; Salas, Javier

2016-08-01

Groundwater deficits occur in several areas of Central Mexico, where water resource assessment is limited by the availability and reliability of field data. In this context, GRACE and InSAR are used to remotely assess groundwater storage loss in one of Mexico's most important watersheds in terms of size and economic activity: the Lerma-Santiago-Pacifico (LSP). In situ data and Land Surface Models are used to subtract soil moisture and surface water storage changes from the total water storage change measured by GRACE satellites. As a result, groundwater mass change time-series are obtained for a 12 years period. ALOS-PALSAR images acquired from 2007 to 2011 were processed using the SBAS-InSAR algorithm to reveal areas subject to ground motion related to groundwater over-exploitation. In the perspective of providing guidance for groundwater management, GRACE and InSAR observations are compared with official water budgets and field observations. InSAR-derived subsidence mapping generally agrees well with official water budgets, and shows that deficits occur mainly in cities and irrigated agricultural areas. GRACE does not entirely detect the significant groundwater losses largely reported by official water budgets, literature and InSAR observations. The difference is interpreted as returns of wastewater to the groundwater flow systems, which limits the watershed scale groundwater depletion but suggests major impacts on groundwater quality. This phenomenon is enhanced by ground fracturing as noticed in the field. Studying the fate of the extracted groundwater is essential when comparing GRACE data with higher resolution observations, and particularly in the perspective of further InSAR/GRACE combination in hydrogeology.

Application of InSAR and Gravimetry for Land Subsidence Hazard Zoning in Aguascalientes, Mexico

Directory of Open Access Journals (Sweden)

Jesús Pacheco-Martínez

2015-12-01

Full Text Available In this work we present an application of InSAR and gravimetric surveys for risk management related to land subsidence and surface ground faulting generation. A subsidence velocity map derived from the 2007–2011 ALOS SAR imagery and a sediment thicknesses map obtained from the inversion of gravimetric data were integrated with a surface fault map to produce a subsidence hazard zoning in the city of Aguascalientes, Mexico. The resulting zoning is presented together with specific recommendations about geotechnical studies needed for further evaluation of surface faulting in these hazard zones. The derived zoning map consists in four zones including null hazard (stable terrain without subsidence, low hazard (areas prone to subsidence, medium hazard (zones with subsidence and high hazard (zones with surface faulting. InSAR results displayed subsidence LOS velocities up to 10 cm/year and two subsidence areas unknown before this study. Gravimetric results revealed that the thicker sediment sequence is located toward north of Aguascalientes City reaching up to 600 m in thickness, which correspond to a high subsidence LOS velocity zone (up to 6 cm/year.

Radio Interferometric Research of Ionosphere by Signals of Space Satellites

Directory of Open Access Journals (Sweden)

Dugin N.

2013-03-01

Full Text Available Since 2012, the Radiophysical Research Institute and the Lobachevsky State University at Nizhny Novgorod, Russia and the Ventspils International Radio Astronomy Centre at Irbene, Latvia are making radio interferometric experiments on study of ionosphere parameters in a quiet (natural state of medium and research of artificial turbulence of the ionosphere, heated by the emission from the SURA facility. Remote diagnostics of the ionosphere is implemented using a method of radio sounding by signals of navigation satellites in combination with the Very Long Baseline Interferometry (VLBI method. As a result of spectral and correlation analysis, interferometric responses of the two-element (RRI–UNN and three-element (RRI–UNN–Irbene interferometers were received by observations of 12 satellites of the navigation systems GLONASS and GPS. Here the first results are reported.

Linear projection of technical noise for interferometric gravitational-wave detectors

International Nuclear Information System (INIS)

Smith, J R; Ajith, P; Grote, H; Hewitson, M; Hild, S; Lueck, H; Strain, K A; Willke, B; Hough, J; Danzmann, K

2006-01-01

An international network of interferometric gravitational-wave detectors is now in operation, and has entered a period of intense commissioning focused on bringing the instruments to their theoretical sensitivity limits. To expedite this process, noise analysis techniques have been developed by the groups associated with each instrument. We present methods of noise analysis that were developed and utilized for the commissioning of the GEO 600 detector. The focal point of this paper is a technique called noise projection that is used to determine the levels of contribution of various noise sources to the detector output. Example applications of this method to control loops typical of those employed in an interferometric GW detector are presented. Possible extensions of noise projections, including technical noise subtraction and gravitational-wave vetoes are also discussed

All-optical 40 Gbit/s compact integrated interferometric wavelength converter

DEFF Research Database (Denmark)

Jørgensen, Carsten; Danielsen, Søren Lykke; Hansen, Peter Bukhave

1997-01-01

An interferometric Michelson wavelength converter is presented that combines a speed-optimized semiconductor optical amplifier technology with the benefits of the integrated interferometer showing 40-Gbit/s wavelength conversion. The optimized wavelength converter demonstrates noninverted converted...

A NEW HIGH-RESOLUTION ELEVATION MODEL OF GREENLAND DERIVED FROM TANDEM-X

Directory of Open Access Journals (Sweden)

B. Wessel

2016-06-01

Full Text Available In this paper we present for the first time the new digital elevation model (DEM for Greenland produced by the TanDEM-X (TerraSAR add-on for digital elevation measurement mission. The new, full coverage DEM of Greenland has a resolution of 0.4 arc seconds corresponding to 12 m. It is composed of more than 7.000 interferometric synthetic aperture radar (InSAR DEM scenes. X-Band SAR penetrates the snow and ice pack by several meters depending on the structures within the snow, the acquisition parameters, and the dielectricity constant of the medium. Hence, the resulting SAR measurements do not represent the surface but the elevation of the mean phase center of the backscattered signal. Special adaptations on the nominal TanDEM-X DEM generation are conducted to maintain these characteristics and not to raise or even deform the DEM to surface reference data. For the block adjustment, only on the outer coastal regions ICESat (Ice, Cloud, and land Elevation Satellite elevations as ground control points (GCPs are used where mostly rock and surface scattering predominates. Comparisons with ICESat data and snow facies are performed. In the inner ice and snow pack, the final X-Band InSAR DEM of Greenland lies up to 10 m below the ICESat measurements. At the outer coastal regions it corresponds well with the GCPs. The resulting DEM is outstanding due to its resolution, accuracy and full coverage. It provides a high resolution dataset as basis for research on climate change in the arctic.

Advanced Virgo: a second-generation interferometric gravitational wave detector

NARCIS (Netherlands)

Acernese, F.; Bulten, H.J.; Rabeling, D.S.; van den Brand, J.F.J.

2015-01-01

Advanced Virgo is the project to upgrade the Virgo interferometric detector of gravitational waves, with the aim of increasing the number of observable galaxies (and thus the detection rate) by three orders of magnitude. The project is now in an advanced construction phase and the assembly and

InSAR coherence study of unusual rain events in the Atacama Desert

Science.gov (United States)

Jordan, T. E.; Scott, C. P.; Lohman, R.

2017-12-01

The Atacama Desert (AD) occupies much of Chile at latitudes 18-27°S. The surficial materials vary, dependent on proximity to the ocean, slope, position within a surface water drainage system, mean annual rainfall, human land disturbance, and the local history of climate changes. Three major divisions of soil composition include: near coastal zone of silicate mineral soils, mostly devoid of plants; central hyperarid zone dominated by gypsum, devoid of plants; eastern zone of silicate-based soils, very sparse plants. The AD in March 2015 experienced the largest rain event of modern history, and again in June 2017 almost as much rain fell within the study area (24.2-25.7°S, coast to Andes Mountains). Those natural experiments set the stage for InSAR remote sensing of surface changes in a 24,000 square kilometer area. We used interferometric coherence of radar to measure the similarity in the reflective ground properties at the time of two SAR acquisitions, and a time series of European Space Agency's Sentinel-1A data sets acquired between January 2015 and August 2017. Date pairs lacking an intervening rain event reveal extensive regions of high coherence, and in those areas we focus on the temporal evolution of coherence across dates of, and following dates of, the major rains. Permanent change of the surface is most extensive in the eastern and western sectors, yet the degree of permanent change was small except in valley bottoms. In the sector with gypsum soil small degrees of permanent change occurred over 30% of the surface including in narrow (1-3 km) elongate (10-60 km) stripes that cross-cut topography, likely revealing rain bands. The spatial pattern of transient change in coherence differs. Over half the gypsum-dominated zone displays a transient change signal, whose spatial pattern corresponds to geomorphological forms; older landforms display greater transient coherence changes. In the silicate-dominated eastern region the transient signals are smaller

A prototype of an automated high resolution InSAR volcano-monitoring system in the MED-SUV project

Science.gov (United States)

Chowdhury, Tanvir A.; Minet, Christian; Fritz, Thomas

2016-04-01

Volcanic processes which produce a variety of geological and hydrological hazards are difficult to predict and capable of triggering natural disasters on regional to global scales. Therefore it is important to monitor volcano continuously and with a high spatial and temporal sampling rate. The monitoring of active volcanoes requires the reliable measurement of surface deformation before, during and after volcanic activities and it helps for the better understanding and modelling of the involved geophysical processes. Space-borne synthetic aperture radar (SAR) interferometry (InSAR), persistent scatterer interferometry (PSI) and small baseline subset algorithm (SBAS) provide a powerful tool for observing the eruptive activities and measuring the surface changes of millimetre accuracy. All the mentioned techniques with deformation time series extraction address the challenges by exploiting medium to large SAR image stacks. The process of selecting, ordering, downloading, storing, logging, extracting and preparing the data for processing is very time consuming has to be done manually for every single data-stack. In many cases it is even an iterative process which has to be done regularly and continuously. Therefore, data processing becomes slow which causes significant delays in data delivery. The SAR Satellite based High Resolution Data Acquisition System, which will be developed at DLR, will automate this entire time consuming tasks and allows an operational volcano monitoring system. Every 24 hours the system runs for searching new acquired scene over the volcanoes and keeps track of the data orders, log the status and download the provided data via ftp-transfer including E-Mail alert. Furthermore, the system will deliver specified reports and maps to a database for review and use by specialists. The user interaction will be minimized and iterative processes will be totally avoided. In this presentation, a prototype of SAR Satellite based High Resolution Data

Multi-temporal InSAR evidence of ground subsidence induced by groundwater withdrawal: the Montellano aquifer (SW Spain)

NARCIS (Netherlands)

Ruiz-Constán, A.; Ruiz-Armenteros, A.M.; Lamas-Fernández, F.; Martos-Rosillo, S.; Delgado, J.M.; Bekaert, D.P.S.; Sousa, J.J.; Gil, A.J.; Caro Cuenca, M.; Hanssen, R.F.; Galindo-Zaldívar, J.; Sanz de Galdeano, C.

2016-01-01

This study uses the InSAR technique to analyse ground subsidence due to intensive exploitation of an aquifer for agricultural and urban purposes in the Montellano town (SW Spain). The detailed deformation maps clearly show that the spatial and temporal extent of subsidence is controlled by

Pump-induced optical distortions in disk amplifier modules: holographic and interferometric measurements

International Nuclear Information System (INIS)

Linford, G.J.; Chau, H.H.; Glaze, J.A.; Layne, C.B.; Rainer, F.

1975-01-01

Interferometric measurements have been made of the optical distortions induced in laser disk amplifiers during the flashlamp pumping pulse. Both conventional interferometric methods and the techniques of double exposure holographic interferometry were used to identify four major sources of pump-induced optical distortions: subsonic intrusion of hot gas (traced to leakage of atmospheric oxygen into the amplifier), microexplosions of dust particles, thermally induced optical distortions in the glass disks, and gaseous optical distortion effects caused by turbulent flow of the purging nitrogen gas supply used within the laser amplifier head. Methods for reducing or eliminating the effects of each of these optical distortions are described

Interferometric architectures based All-Optical logic design methods and their implementations

Science.gov (United States)

Singh, Karamdeep; Kaur, Gurmeet

2015-06-01

All-Optical Signal Processing is an emerging technology which can avoid costly Optical-electronic-optical (O-E-O) conversions which are usually compulsory in traditional Electronic Signal Processing systems, thus greatly enhancing operating bit rate with some added advantages such as electro-magnetic interference immunity and low power consumption etc. In order to implement complex signal processing tasks All-Optical logic gates are required as backbone elements. This review describes the advances in the field of All-Optical logic design methods based on interferometric architectures such as Mach-Zehnder Interferometer (MZI), Sagnac Interferometers and Ultrafast Non-Linear Interferometer (UNI). All-Optical logic implementations for realization of arithmetic and signal processing applications based on each interferometric arrangement are also presented in a categorized manner.

InSAR Time Series Analysis and Geophysical Modeling of City Uplift Associated with Geothermal Drillings in Staufen im Breisgau, Germany

Science.gov (United States)

Motagh, M.; Lubitz, C.

2014-12-01

Geothermal energy is of increasing importance as alternative, environmentally friendly technology for heat management. Direct interaction with the subsurface requires careful implementation, in particular in geological complex regions. The historical city Staufen im Breisgau, SW Germany, has attracted national attention as a case of implementation failure with severe consequences, causing debates on the applicability and security of this sustainable technique. Located at the eastern transition zone of the Upper Rhine Graben and the Schwarzwald massif, the geothermal potential is high at Staufen due to strong temperature gradients. In September 2007, seven boreholes for geothermal probes were drilled up to a depth of 140 m to provide a new heat management for the city hall. Within five years an uplift phenomenon has been observed in Staufen reaching more than 40 cm in places and 269 buildings were damaged. Hydro-chemical driven anhydrite-gypsum transformation in the subsurface was identified as the cause leading to volume increase that is observable as surface uplift. This process is associated with the geothermal drilling activities that have crossed several groundwater levels. In this work, we summarize and present the findings of spaceborne Synthetic Aperture Radar Interferometry (InSAR) analysis of the uplift in Staufen over the last five years from July 2008 through July 2013. By applying the Small Baseline Subset (SBAS) method, we find a localized elliptical-shaped deformation field in NE-SW orientation. Area of maximum uplift is located 50 m NNE of the drilling zone. At this location, we observe a cumulative uplift of approx. 13.7 cm ± 0.34 cm (mean value within an area of 30 m by 30 m) from July 2008 to July 2009, which reduced to cumulative uplift of 3 cm ± 0.25 cm from July 2012 to July 2013. The deceleration can be related to applied countermeasures as borehole sealing and groundwater pumping. The observed ground surface response was compared to

Spatiotemporal characteristics of the Huangtupo landslide in the Three Gorges region (China) constrained by radar interferometry

Science.gov (United States)

Tomás, R.; Li, Z.; Liu, P.; Singleton, A.; Hoey, T.; Cheng, X.

2014-04-01

The Huangtupo landslide is one of the largest in the Three Gorges region, China. The county-seat town of Badong, located on the south shore between the Xiling and Wu gorges of the Yangtze River, was moved to this unstable slope prior to the construction of the Three Gorges Project, since the new Three Gorges reservoir completely submerged the location of the old city. The instability of the slope is affecting the new town by causing residential safety problems. The Huangtupo landslide provides scientists an opportunity to understand landslide response to fluctuating river water level and heavy rainfall episodes, which is essential to decide upon appropriate remediation measures. Interferometric Synthetic Aperture Radar (InSAR) techniques provide a very useful tool for the study of superficial and spatially variable displacement phenomena. In this paper, three sets of radar data have been processed to investigate the Huangtupo landslide. Results show that maximum displacements are affecting the northwest zone of the slope corresponding to Riverside slumping mass I#. The other main landslide bodies (i.e. Riverside slumping mass II#, Substation landslide and Garden Spot landslide) exhibit a stable behaviour in agreement with in situ data, although some active areas have been recognized in the foot of the Substation landslide and Garden Spot landslide. InSAR has allowed us to study the kinematic behaviour of the landslide and to identify its active boundaries. Furthermore, the analysis of the InSAR displacement time-series has helped recognize the different displacement patterns on the slope and their relationships with various triggering factors. For those persistent scatterers, which exhibit long-term displacements, they can be decomposed into a creep model (controlled by geological conditions) and a superimposed recoverable term (dependent on external factors), which appears closely correlated with reservoir water level changes close to the river's edge. These

StaMPS Improvement for Deformation Analysis in Mountainous Regions: Implications for the Damavand Volcano and Mosha Fault in Alborz

Directory of Open Access Journals (Sweden)

Sanaz Vajedian

2015-06-01

Full Text Available Interferometric Synthetic Aperture Radar (InSAR capability to detect slow deformation over terrain areas is limited by temporal decorrelation, geometric decorrelation and atmospheric artefacts. Multitemporal InSAR methods such as Persistent Scatterer (PS-InSAR and Small Baseline Subset (SBAS have been developed to deal with various aspects of decorrelation and atmospheric problems affecting InSAR observations. Nevertheless, the applicability of both PS-InSAR and SBAS in mountainous regions is still challenging. Correct phase unwrapping in both methods is hampered due to geometric decorrelation in particular when using C-band SAR data for deformation analysis. In this paper, we build upon the SBAS method implemented in StaMPS software and improved the technique, here called ISBAS, to assess tectonic and volcanic deformation in the center of the Alborz Mountains in Iran using both Envisat and ALOS SAR data. We modify several aspects within the chain of the processing including: filtering prior to phase unwrapping, topographic correction within three-dimensional phase unwrapping, reducing the atmospheric noise with the help of additional GPS data, and removing the ramp caused by ionosphere turbulence and/or orbit errors to better estimate crustal deformation in this tectonically active region. Topographic correction is done within the three-dimensional unwrapping in order to improve the phase unwrapping process, which is in contrast to previous methods in which DEM error is estimated before/after phase unwrapping. Our experiments show that our improved SBAS approach is able to better characterize the tectonic and volcanic deformation in the center of the Alborz region than the classical SBAS. In particular, Damavand volcano shows an average uplift rate of about 3 mm/year in the year 2003–2010. The Mosha fault illustrates left-lateral motion that could be explained with a fault that is locked up to 17–18 km depths and slips with 2–4 mm

Geodetic evidence for en echelon dike emplacement and concurrent slow slip during the June 2007 intrusion and eruption at Kīlauea volcano, Hawaii

Science.gov (United States)

Montgomery-Brown, E. K.; Sinnett, D.K.; Poland, M.; Segall, P.; Orr, T.; Zebker, H.; Miklius, Asta

2010-01-01

A series of complex events at Kīlauea Volcano, Hawaii, 17 June to 19 June 2007, began with an intrusion in the upper east rift zone (ERZ) and culminated with a small eruption (1500 m3). Surface deformation due to the intrusion was recorded in unprecedented detail by Global Positioning System (GPS) and tilt networks as well as interferometric synthetic aperture radar (InSAR) data acquired by the ENVISAT and ALOS satellites. A joint nonlinear inversion of GPS, tilt, and InSAR data yields a deflationary source beneath the summit caldera and an ENE-striking uniform-opening dislocation with ~2 m opening, a dip of ∼80° to the south, and extending from the surface to ~2 km depth. This simple model reasonably fits the overall pattern of deformation but significantly misfits data near the western end of an inferred dike-like source. Three more complex dike models are tested that allow for distributed opening including (1) a dike that follows the surface trace of the active rift zone, (2) a dike that follows the symmetry axis of InSAR deformation, and (3) two en echelon dike segments beneath mapped surface cracks and newly formed steaming areas. The en echelon dike model best fits near-field GPS and tilt data. Maximum opening of 2.4 m occurred on the eastern segment beneath the eruptive vent. Although this model represents the best fit to the ERZ data, it still fails to explain data from a coastal tiltmeter and GPS sites on Kīlauea's southwestern flank. The southwest flank GPS sites and the coastal tiltmeter exhibit deformation consistent with observations of previous slow slip events beneath Kīlauea's south flank, but inconsistent with observations of previous intrusions. Slow slip events at Kīlauea and elsewhere are thought to occur in a transition zone between locked and stably sliding zones of a fault. An inversion including slip on a basal decollement improves fit to these data and suggests a maximum of ~15 cm of seaward fault motion, comparable to previous slow

The Subsidence Signature Due To Groundwater Extraction as Inferred from Remote Sensing Data in Mexico City

Science.gov (United States)

Patel, V.; Chen, J.

2015-12-01

Mexico City is facing a severe water shortage; current drought conditions in the city have led to an increase in the demand for groundwater, the pumping of which can cause significant land subsidence. In this study we explored what new information interferometric synthetic aperture radar (InSAR) data collected by the TerraSAR-X satellite could bring to water resource managers in the city so that they can efficiently and sustainably allocate water resources. Previous work done over Mexico City indicates that InSAR can be used to detect deformation due to groundwater pumping. Cabral-Cano et al. (2008) processed InSAR data acquired from ERS between 1996-2000 and from ENVISAT between 2003-2005. They compared the deformation map to geology maps of the region with information obtained by seismic methods. They found that a spatial correlation between the land deformation and the presence of young lacustrine clay beds, which indicate that the subsidence was caused by fluid pressure loss in the aquitard. They also concluded that the subsidence, for the most part, had no seasonal variation and continues to occur at near-constant, high rates. TerraSAR-­X satellite data is known to be more sensitive to small deformations than the data from satellites used in previous studies in the region because of its frequent revisit cycle, short wavelength, and accurate orbital information. For this project, we derived long sequences of crustal deformation time series from TerraSAR-­X data between May 2011 and December 2012 using the Small Baseline Subset (SBAS) method. The resulting time series was then compared to GPS data for calibration and validation. We observed a long-term deformation that was similar to those found in previous studies. The next step in our work is to determine whether the increased sensitivity of the TerraSAR-­X data allows us to detect a seasonal deformation pattern over the study area.

Improved self-reliance shearing interferometric technique for collimation testing

Science.gov (United States)

Zhao, Mingshan; Li, Guohua; Wang, Zhaobing; Jing, Yaling; Li, Yi

1995-06-01

Self-reference single plate shearing interferometric technique used for collimation testing of light beams are briefly reviewed. Two improved configurations of this self-reference interferometry with an inclined screen and matched half-field interferograms are described in detail. Sensitivity of these configurations is analyzed and compared with that of the existing ones.

Robust sparse image reconstruction of radio interferometric observations with PURIFY

Science.gov (United States)

Pratley, Luke; McEwen, Jason D.; d'Avezac, Mayeul; Carrillo, Rafael E.; Onose, Alexandru; Wiaux, Yves

2018-01-01

Next-generation radio interferometers, such as the Square Kilometre Array, will revolutionize our understanding of the Universe through their unprecedented sensitivity and resolution. However, to realize these goals significant challenges in image and data processing need to be overcome. The standard methods in radio interferometry for reconstructing images, such as CLEAN, have served the community well over the last few decades and have survived largely because they are pragmatic. However, they produce reconstructed interferometric images that are limited in quality and scalability for big data. In this work, we apply and evaluate alternative interferometric reconstruction methods that make use of state-of-the-art sparse image reconstruction algorithms motivated by compressive sensing, which have been implemented in the PURIFY software package. In particular, we implement and apply the proximal alternating direction method of multipliers algorithm presented in a recent article. First, we assess the impact of the interpolation kernel used to perform gridding and degridding on sparse image reconstruction. We find that the Kaiser-Bessel interpolation kernel performs as well as prolate spheroidal wave functions while providing a computational saving and an analytic form. Secondly, we apply PURIFY to real interferometric observations from the Very Large Array and the Australia Telescope Compact Array and find that images recovered by PURIFY are of higher quality than those recovered by CLEAN. Thirdly, we discuss how PURIFY reconstructions exhibit additional advantages over those recovered by CLEAN. The latest version of PURIFY, with developments presented in this work, is made publicly available.

SAR interferometry applications on active volcanoes. State of the art and perspectives for volcano monitoring

Energy Technology Data Exchange (ETDEWEB)

Puglisi, G.; Coltelli, M. [Istituto Nazionale di Geofisica e Vulcanologia, Catania (Italy)

2001-02-01

In this paper the application of the Synthetic Aperture Radar Interferometry (INSAR) on volcanology is analysed. Since it is not a real novelty among the different applications of INSAR in Earth Observation activities, at the beginning of this paper it is analysed the state of the art of the researches in this field. During the discussion, the point of view of volcanologists is favoured because it is considered that the first applications were often badly aimed. Consequently, the initial INSAR performances in volcanology were overrated with respect to the real capabilities of this technique. This fact lead to discover some unexpected limitations in INSAR usage in volcano monitoring, but, at the same time, spurred on scientists to overcome these drawbacks. The results achieved recently allow to better apply SAR to volcanology; in the paper a possible operative work-plan aimed at introducing INSAR in the volcano monitoring system is presented.

Geodetic Measurements and Numerical Models of Rifting in Northern Iceland for 1993-1999

Science.gov (United States)

Ali, T.; Feigl, K.; Masterlark, T.; Carr, B. B.; Sigmundsson, F.; Thurber, C. H.

2009-12-01

Rifting occurs as episodes of active deformation in individual rift segments of the Northern Volcanic Zone (NVZ) of Iceland. To measure the deformation, we use interferometric analysis of synthetic aperture radar (InSAR) data acquired between 1993 and 1999. Preliminary results suggest that a complex interplay of multiple inflating and deflating sources at depth is required to account for the observed deformation. In an effort to integrate heterogeneous constraining information (kinematic plate spreading, seismic tomography and anisotropy, and thermal and rheologic structures), we develop finite element models that simulate the underlying sources and processes associated with rifting events to quantitatively understand the magmatic plumbing system beneath Krafla central volcano and rift segment, the site of the most recent rifting episode in the NVZ. Calibration parameters include the positions, geometries, and flux rates for elements of the plumbing system, as well as material properties. The General Inversion for Phase Technique (GIPhT) [Feigl and Thurber, Geophys. J. Int., 2009] is used to model the InSAR phase data directly, without unwrapping parameters. It operates on wrapped phase values ranging from -1/2 to +1/2 cycles. By defining a cost function that quantifies the misfit between observed and modeled values in terms of wrapped phase, GIPhT can estimate parameters in a geophysical model by minimizing the cost function. Since this approach can handle noisy, wrapped phase data, it avoids the pitfalls of phase-unwrapping approaches. Consequently, GIPhT allows the analysis, interpretation and modeling of more interferometric pairs than approaches that require unwrapping. GIPhT also allows statistical testing of hypotheses because the wrapped phase residuals follow a Von Mises distribution. As a result, the model parameters estimated by GIPhT include formal uncertainties. We test the hypothesis that deformation in the rift zone occurred at a constant (secular

A high-throughput surface plasmon resonance biosensor based on differential interferometric imaging

International Nuclear Information System (INIS)

Wang, Daqian; Ding, Lili; Zhang, Wei; Zhang, Enyao; Yu, Xinglong; Luo, Zhaofeng; Ou, Huichao

2012-01-01

A new high-throughput surface plasmon resonance (SPR) biosensor based on differential interferometric imaging is reported. The two SPR interferograms of the sensing surface are imaged on two CCD cameras. The phase difference between the two interferograms is 180°. The refractive index related factor (RIRF) of the sensing surface is calculated from the two simultaneously acquired interferograms. The simulation results indicate that the RIRF exhibits a linear relationship with the refractive index of the sensing surface and is unaffected by the noise, drift and intensity distribution of the light source. The affinity and kinetic information can be extracted in real time from continuously acquired RIRF distributions. The results of refractometry experiments show that the dynamic detection range of SPR differential interferometric imaging system can be over 0.015 refractive index unit (RIU). High refractive index resolution is down to 0.45 RU (1 RU = 1 × 10 −6 RIU). Imaging and protein microarray experiments demonstrate the ability of high-throughput detection. The aptamer experiments demonstrate that the SPR sensor based on differential interferometric imaging has a great capability to be implemented for high-throughput aptamer kinetic evaluation. These results suggest that this biosensor has the potential to be utilized in proteomics and drug discovery after further improvement. (paper)

Complex faulting associated with the 22 December 2003 Mw 6.5 San Simeon California, earthquake, aftershocks and postseismic surface deformation

Science.gov (United States)

McLaren, Marcia K.; Hardebeck, Jeanne L.; Van Der Elst, Nicholas; Unruh, Jeffrey R.; Bawden, Gerald W.; Blair, James Luke

2008-01-01

We use data from two seismic networks and satellite interferometric synthetic aperture radar (InSAR) imagery to characterize the 22 December 2003 Mw 6.5 San Simeon earthquake sequence. Absolute locations for the mainshock and nearly 10,000 aftershocks were determined using a new three-dimensional (3D) seismic velocity model; relative locations were obtained using double difference. The mainshock location found using the 3D velocity model is 35.704° N, 121.096° W at a depth of 9.7±0.7 km. The aftershocks concentrate at the northwest and southeast parts of the aftershock zone, between the mapped traces of the Oceanic and Nacimiento fault zones. The northwest end of the mainshock rupture, as defined by the aftershocks, projects from the mainshock hypocenter to the surface a few kilometers west of the mapped trace of the Oceanic fault, near the Santa Lucia Range front and the >5 mm postseismic InSAR imagery contour. The Oceanic fault in this area, as mapped by Hall (1991), is therefore probably a second-order synthetic thrust or reverse fault that splays upward from the main seismogenic fault at depth. The southeast end of the rupture projects closer to the mapped Oceanic fault trace, suggesting much of the slip was along this fault, or at a minimum is accommodating much of the postseismic deformation. InSAR imagery shows ∼72 mm of postseismic uplift in the vicinity of maximum coseismic slip in the central section of the rupture, and ∼48 and ∼45 mm at the northwest and southeast end of the aftershock zone, respectively. From these observations, we model a ∼30-km-long northwest-trending northeast-dipping mainshock rupture surface—called the mainthrust—which is likely the Oceanic fault at depth, a ∼10-km-long southwest-dipping backthrust parallel to the mainthrust near the hypocenter, several smaller southwest-dipping structures in the southeast, and perhaps additional northeast-dipping or subvertical structures southeast of the mainshock plane

Shortcomings of InSAR for studying megathrust earthquakes: The case of the M w 9.0 Tohoku-Oki earthquake

KAUST Repository

Feng, Guangcai; Jonsson, Sigurjon

2012-01-01

.0) and test InSAR-derived fault-slip models against models constrained by GPS data from the extensive nationwide network in Japan. The coseismic deformation field was mapped using InSAR data acquired from multiple ascending and descending passes of the ALOS

Application of InSAR and Gravimetry for Land Subsidence Hazard Zoning in Aguascalientes, Mexico

OpenAIRE

Pacheco-Martínez, Jesús; Cabral-Cano, Enrique; Wdowinski, Shimon; Hernández-Marín, Martín; Ortiz-Lozano, José; Zermeño-de-León, Mario

2015-01-01

In this work we present an application of InSAR and gravimetric surveys for risk management related to land subsidence and surface ground faulting generation. A subsidence velocity map derived from the 2007–2011 ALOS SAR imagery and a sediment thicknesses map obtained from the inversion of gravimetric data were integrated with a surface fault map to produce a subsidence hazard zoning in the city of Aguascalientes, Mexico. The resulting zoning is presented together with specific recommendation...

Intermittent Small Baseline Subset (ISBAS) InSAR of rural and vegetated terrain: a new method to monitor land motion applied to peatlands in Wales, UK

Science.gov (United States)

Cigna, Francesca; Rawlins, Barry G.; Jordan, Colm J.; Sowter, Andrew; Evans, Christopher D.

2014-05-01

It is renowned that the success of multi-interferometric Synthetic Aperture Radar (SAR) methods such as Persistent Scatterer Interferometry (PSI) and Small BASeline Subset (SBAS) is controlled by not only the availability of data, but also local topography and land cover. Locations with sufficient temporal phase stability and coherence are typically limited to either built-up, urban areas or areas of exposed bedrock. Whilst conventional PSI and SBAS approaches have limited potential to monitor surface motions in areas where few (or zero) scatterers or coherent targets exist, the newly developed Intermittent SBAS (ISBAS) technique (Sowter et al. 2013) can fill the gap by providing a more complete picture of ground movement in rural and vegetated regions. ISBAS is a small baseline, multi-look, coherent target method, which considers the intermittent coherence of rural areas and can work over a wide range of land cover classes including agriculture and grassland. Building upon a nationwide study that the British Geological Survey (BGS) undertook to assess the feasibility of InSAR techniques to monitor the landmass of Great Britain (Cigna et al. 2013), we identified a rural region in North Wales as an appropriate target area to evaluate the efficacy of ISBAS, where conventional SBAS and PSI approaches are unlikely to succeed. According to the UK Land Cover Map 2007 (LCM2007) from the Centre for Ecology & Hydrology (CEH), this area is dominated by improved and acid grassland, heather, bog and coniferous woodland, which are likely to result into extremely low PSI or SBAS point densities and sparse coverage of monitoring results. We employed 53 ERS-1/2 C-band (5.3GHz frequency) SAR data acquired in descending mode between 1993 and 2000, which were made available to BGS via the ESA Category 1 project id.13543. In the framework of the Glastir Monitoring & Evaluation Programme (Emmett et al. 2013), funded by the Welsh Government, we processed these using ISBAS covering a 4

Multi-Wavelength Interferometric Observations of YSO Disks

Science.gov (United States)

Ragland, Sam; Akeson, R.; Armandroff, T.; Colavita, M.; Cotton, W.; Danchi, W.; Hillenbrand, L.; Millan-Gabet, R.; Ridgway, S. T.; Traub, W.; Wizinowich, P.

2010-01-01

We initiated a multi-color interferometric study of YSO disks in the K, L and N bands using the Keck Interferometer. The initial results on two Herbig Ae/Be stars will be presented. Our observations are sensitive to the radial distribution of temperature in the inner region of the YSO disks. The geometric models show that the apparent size increases linearly with wavelength, suggesting that the disk is extended with a temperature gradient. We will discuss our results in conjunction with the previous measurements of these targets.

The 2008 Wells, Nevada earthquake sequence: Source constraints using calibrated multiple event relocation and InSAR

Science.gov (United States)

Nealy, Jennifer; Benz, Harley M.; Hayes, Gavin; Berman, Eric; Barnhart, William

2017-01-01

The 2008 Wells, NV earthquake represents the largest domestic event in the conterminous U.S. outside of California since the October 1983 Borah Peak earthquake in southern Idaho. We present an improved catalog, magnitude complete to 1.6, of the foreshock-aftershock sequence, supplementing the current U.S. Geological Survey (USGS) Preliminary Determination of Epicenters (PDE) catalog with 1,928 well-located events. In order to create this catalog, both subspace and kurtosis detectors are used to obtain an initial set of earthquakes and associated locations. The latter are then calibrated through the implementation of the hypocentroidal decomposition method and relocated using the BayesLoc relocation technique. We additionally perform a finite fault slip analysis of the mainshock using InSAR observations. By combining the relocated sequence with the finite fault analysis, we show that the aftershocks occur primarily updip and along the southwestern edge of the zone of maximum slip. The aftershock locations illuminate areas of post-mainshock strain increase; aftershock depths, ranging from 5 to 16 km, are consistent with InSAR imaging, which shows that the Wells earthquake was a buried source with no observable near-surface offset.

Spatial and temporal patterns of deformation at the Tendaho geothermal prospect, Ethiopia

Science.gov (United States)

Temtime, Tesfaye; Biggs, Juliet; Lewi, Elias; Hamling, Ian; Wright, Tim; Ayele, Atalay

2018-05-01

Observations of ground deformation in East Africa have been fundamental for unveiling the tectonics of continental rifting, assessing the seismic and volcanic hazard to development, and identifying geothermal resources. Here we investigate the active natural and anthropogenic processes in the Tendaho Graben, Afar using Interferometric Synthetic Aperture Radar (InSAR) collected by the Envisat satellite in 2004-2010. We used the Poly-Interferometric Rate And time series Estimation (π-RATE) method to calculate displacement in satellite line-of-sight, and a least-square inversion to decompose the line-of-sight displacement into vertical and rift perpendicular components. We observe two zones of deformation: a 20 km wide circular region of subsidence located 10 km northeast of the town of Semera with a maximum displacement rate of ∼5 cm/yr; and elongated zone (50 km) of subsidence in the area of the geothermal prospect, maximum rate of ∼4 cm/yr. The temporal characteristics of subsidence varies between these zones, with an increase in subsidence rate observed in the circular region in August 2008. We used a Bayesian inversion to find the best fitting source models and compared this to locations of seismicity and other geophysical observations. The pattern of deformation is consistent with a combination of magmatic and geothermal processes, but there does not appear to be a direct link to a sequence of dyke intrusions during 2005-2010 at Manda Hararo graben ∼60 km away, but dynamic stress changes or deep crustal flow could account for the observations.

Understanding earthquakes: The key role of radar images

International Nuclear Information System (INIS)

Atzori, Simone

2013-01-01

The investigation of the fault rupture underlying earthquakes greatly improved thanks to the spread of radar images. Following pioneer applications in the eighties, Interferometry from Synthetic Aperture Radar (InSAR) gained a prominent role in geodesy. Its capability to measure millimetric deformations for wide areas and the increased data availability from the early nineties, made InSAR a diffused and accepted analysis tool in tectonics, though several factors contribute to reduce the data quality. With the introduction of analytical or numerical modeling, InSAR maps are used to infer the source of an earthquake by means of data inversion. Newly developed algorithms, known as InSAR time-series, allowed to further improve the data accuracy and completeness, strengthening the InSAR contribution even in the study of the inter- and post-seismic phases. In this work we describe the rationale at the base of the whole processing, showing its application to the New Zealand 2010–2011 seismic sequence

Understanding earthquakes: The key role of radar images

Energy Technology Data Exchange (ETDEWEB)

Atzori, Simone, E-mail: simone.atzori@ingv.it [Istituto Nazionale di Geofisica e Vulcanologia, Rome (Italy)

2013-08-21

The investigation of the fault rupture underlying earthquakes greatly improved thanks to the spread of radar images. Following pioneer applications in the eighties, Interferometry from Synthetic Aperture Radar (InSAR) gained a prominent role in geodesy. Its capability to measure millimetric deformations for wide areas and the increased data availability from the early nineties, made InSAR a diffused and accepted analysis tool in tectonics, though several factors contribute to reduce the data quality. With the introduction of analytical or numerical modeling, InSAR maps are used to infer the source of an earthquake by means of data inversion. Newly developed algorithms, known as InSAR time-series, allowed to further improve the data accuracy and completeness, strengthening the InSAR contribution even in the study of the inter- and post-seismic phases. In this work we describe the rationale at the base of the whole processing, showing its application to the New Zealand 2010–2011 seismic sequence.

Event reconstruction using the radio-interferometric technique in the frame of AERA

Energy Technology Data Exchange (ETDEWEB)

Rogozin, Dmytro [Institut fuer Experimentelle Kernphysik, Karlsruher Institut fuer Technologie (KIT) (Germany); Collaboration: Pierre-Auger-Collaboration

2016-07-01

It is a well-known fact that there is coherent radio emission induced by extensive air-showers. This fact is exploited in the Auger Engineering Radio Array (AERA), the radio extension of the Pierre Auger Observatory. This is a unique radio experiment due to its world-largest size of 17 km{sup 2}, and due to its precise nanosecond timing calibration. These features become crucial for detection of highly inclined air-showers with their very large foot-prints, and for the ability to apply interferometric reconstruction techniques. The standard reconstruction techniques typically treat all radio stations as separate detectors. Nevertheless there is a possibility to do an interferometric analysis. This means combining all detected signals from all antennas in a specific way. In this talk we present a beam-forming interferometric technique and its application to AERA. According to the definition of the beam-forming quantities one can expect its correlation with the shower parameters such as energy of the primary particle and distance to the shower maximum. At the first step, Monte-Carlo simulations of AERA events including the noise from measured events were used to test these dependencies. The results and the future perspectives of this method are discussed with a particular emphasis on very inclined air-showers where the aforementioned correlations are assumed to be strongest.

The 2014 interferometric imaging beauty contest

Science.gov (United States)

Monnier, John D.; Berger, Jean-Philippe; Le Bouquin, Jean-Baptiste; Tuthill, Peter G.; Wittkowski, Markus; Grellmann, Rebekka; Müller, André; Renganswany, Sridhar; Hummel, Christian; Hofmann, Karl-Heinz; Schertl, Dieter; Weigelt, Gerd; Young, John; Buscher, David; Sanchez-Bermudez, Joel; Alberdi, Antxon; Schoedel, Rainer; Köhler, Rainer; Soulez, Ferréol; Thiébaut, Éric; Kluska, Jacques; Malbet, Fabien; Duvert, Gilles; Kraus, Stefan; Kloppenborg, Brian K.; Baron, Fabien; de Wit, Willem-Jan; Rivinius, Thomas; Merand, Antoine

2014-07-01

Here we present the results of the 6th biennial optical interferometry imaging beauty contest. Taking advantage of a unique opportunity, the red supergiant VY CMa and the Mira variable R Car were observed in the astronomical H-band with three 4-telescope configurations of the VLTI-AT array using the PIONIER instrument. The community was invited to participate in the subsequent image reconstruction and interpretation phases of the project. Ten groups submitted entries to the beauty contest, and we found reasonable consistency between images obtained from independent workers using quite different algorithms. We also found that significant differences existed between the submitted images, much greater than in past beauty contests that were all based on simulated data. A novel crowd-sourcing" method allowed consensus median images to be constructed, filtering likely artifacts and retaining real features." We definitively detect strong spots on the surfaces of both stars as well as distinct circumstellar shells of emission (likely water/CO) around R Car. In a close contest, Joel Sanchez (IAA-CSIC/Spain) was named the winner of the 2014 interferometric imaging beauty contest. This process has shown that new comers" can use publicly-available imaging software to interpret VLTI/PIONIER imaging data, as long as sufficient observations are taken to have complete uv coverage { a luxury that is often missing. We urge proposers to request adequate observing nights to collect sufficient data for imaging and for time allocation committees to recognise the importance of uv coverage for reliable interpretation of interferometric data. We believe that the result of the proposed broad international project will contribute to inspiring trust in the image reconstruction processes in optical interferometry.

A Differential Polarized Light Interferometric System For Measuring Flatness Of Magnetic Disks

Science.gov (United States)

Jia, Wang; Da-Cheng, Li; Ye, Chen; Ling, Du; Mang, Cao

1987-01-01

A kind of differential polarizdd laser interferometric system for non-contact and dynamic measurement of the flatness characteristic of magnetic disks without the effect of the axial vibration is described in this papper.

Interferometric and optical tests of water window imaging x ray microscopes

Science.gov (United States)

Johnson, R. Barry

1993-01-01

Interferometric tests of Schwarzchild X-ray Microscope are performed to evaluate the optical properties and alignment of the components. Photographic measurements of the spatial resolution, focal properties, and vignetting characteristics of the prototype Water Window Imaging X-ray Microscope are made and analyzed.

Mitigation of defocusing by statics and near-surface velocity errors by interferometric least-squares migration

KAUST Repository

Sinha, Mrinal

2015-08-19

We propose an interferometric least-squares migration method that can significantly reduce migration artifacts due to statics and errors in the near-surface velocity model. We first choose a reference reflector whose topography is well known from the, e.g., well logs. Reflections from this reference layer are correlated with the traces associated with reflections from deeper interfaces to get crosscorrelograms. These crosscorrelograms are then migrated using interferometric least-squares migration (ILSM). In this way statics and velocity errors at the near surface are largely eliminated for the examples in our paper.

Astigmatism compensation in mode-cleaner cavities for the next generation of gravitational wave interferometric detectors

Energy Technology Data Exchange (ETDEWEB)

Barriga, Pablo J. [School of Physics, University of Western Australia, Crawley, WA 6009 (Australia)]. E-mail: pbarriga@cyllene.uwa.edu.au; Zhao Chunnong [School of Physics, University of Western Australia, Crawley, WA 6009 (Australia); Blair, David G. [School of Physics, University of Western Australia, Crawley, WA 6009 (Australia)

2005-06-06

Interferometric gravitational wave detectors use triangular ring cavities to filter spatial and frequency instabilities from the input laser beam. The next generation of interferometric detectors will use high laser power and greatly increased circulating power inside the cavities. The increased power inside the cavities increases thermal effects in their mirrors. The triangular configuration of conventional mode-cleaners creates an intrinsic astigmatism that can be corrected by using the thermal effects to advantage. In this Letter we show that an astigmatism free output beam can be created if the design parameters are correctly chosen.

Astigmatism compensation in mode-cleaner cavities for the next generation of gravitational wave interferometric detectors

International Nuclear Information System (INIS)

Barriga, Pablo J.; Zhao Chunnong; Blair, David G.

2005-01-01

Interferometric gravitational wave detectors use triangular ring cavities to filter spatial and frequency instabilities from the input laser beam. The next generation of interferometric detectors will use high laser power and greatly increased circulating power inside the cavities. The increased power inside the cavities increases thermal effects in their mirrors. The triangular configuration of conventional mode-cleaners creates an intrinsic astigmatism that can be corrected by using the thermal effects to advantage. In this Letter we show that an astigmatism free output beam can be created if the design parameters are correctly chosen

Land subsidence in the San Joaquin Valley, California, USA, 2007-14

Science.gov (United States)

Sneed, Michelle; Brandt, Justin

2015-01-01

Rapid land subsidence was recently measured using multiple methods in two areas of the San Joaquin Valley (SJV): between Merced and Fresno (El Nido), and between Fresno and Bakersfield (Pixley). Recent land-use changes and diminished surface-water availability have led to increased groundwater pumping, groundwater-level declines, and land subsidence. Differential land subsidence has reduced the flow capacity of water-conveyance systems in these areas, exacerbating flood hazards and affecting the delivery of irrigation water. Vertical land-surface changes during 2007–2014 were determined by using Interferometric Synthetic Aperture Radar (InSAR), Continuous Global Positioning System (CGPS), and extensometer data. Results of the InSAR analysis indicate that about 7600 km2 subsided 50–540 mm during 2008–2010; CGPS and extensometer data indicate that these rates continued or accelerated through December 2014. The maximum InSAR-measured rate of 270 mm yr−1 occurred in the El Nido area, and is among the largest rates ever measured in the SJV. In the Pixley area, the maximum InSAR-measured rate during 2008–2010 was 90 mm yr−1. Groundwater was an important part of the water supply in both areas, and pumping increased when land use changed or when surface water was less available. This increased pumping caused groundwater-level declines to near or below historical lows during the drought periods 2007–2009 and 2012–present. Long-term groundwater-level and land-subsidence monitoring in the SJV is critical for understanding the interconnection of land use, groundwater levels, and subsidence, and evaluating management strategies that help mitigate subsidence hazards to infrastructure while optimizing water supplies.

How to spy on your neighbor's water consumption from space

Science.gov (United States)

Neely, W.; Borsa, A. A.; Burney, J. A.

2017-12-01

Dependence on groundwater has increased in the agricultural production regions of California's Central Valley due to recent and persistent droughts. To protect the long-term reliability of groundwater resources in California, the state passed the Sustainable Groundwater Management Act (SGMA) in September 2014. In situ observation of subsurface reservoir levels is ideal for monitoring aquifer health at a water district scale, but is limited by the low density of monitoring wells and temporal gaps between measurements. An alternative to well measurements relies on the fact that groundwater extraction may lead to surface subsidence due to the compaction of the aquifer at depth. Such surface displacements can be resolved using geodetic techniques. We present an integrative approach using Interferometric Synthetic Aperture Radar (InSAR) and continuous Global Positioning System (cGPS) station observations to characterize surface deformation related to extensive pumping at a farm-level resolution every 12-24 days. We demonstrate our technique in the southern Central Valley where we observe subsidence upwards of 25 cm/yr from late 2014 to early 2017. Our methods offer an inexpensive supplement to in situ measurements that allows for the detection and deterrence of water mismanagement.

Simulation of TanDEM-X interferograms for urban change detection

Science.gov (United States)

Welte, Amelie; Hammer, Horst; Thiele, Antje; Hinz, Stefan

2017-10-01

Damage detection after natural disasters is one of the remote sensing tasks in which Synthetic Aperture Radar (SAR) sensors play an important role. Since SAR is an active sensor, it can record images at all times of day and in all weather conditions, making it ideally suited for this task. While with the newer generation of SAR satellites such as TerraSAR-X or COSMOSkyMed amplitude change detection has become possible even for urban areas, interferometric phase change detection has not been published widely. This is mainly because of the long revisit times of common SAR sensors leading to temporal decorrelation. This situation has changed dramatically with the advent of the TanDEM-X constellation, which can create single-pass interferograms from space at very high resolutions, avoiding temporal decorrelation almost completely. In this paper the basic structures that are present for any building in InSAR phases, i.e. layover, shadow, and roof areas, are examined. Approaches for their extraction from TanDEM-X interferograms are developed using simulated SAR interferograms. The extracted features of the building signature will in the future be used for urban change detection in real TanDEM-X High Resolution Spotlight interferograms.

Finite-fault slip model of the 2016 Mw 7.5 Chiloé earthquake, southern Chile, estimated from Sentinel-1 data

Science.gov (United States)

Xu, Wenbin

2017-05-01

Subduction earthquakes have been widely studied in the Chilean subduction zone, but earthquakes occurring in its southern part have attracted less research interest primarily due to its lower rate of seismic activity. Here I use Sentinel-1 interferometric synthetic aperture radar (InSAR) data and range offset measurements to generate coseismic crustal deformation maps of the 2016 Mw 7.5 Chiloé earthquake in southern Chile. I find a concentrated crustal deformation with ground displacement of approximately 50 cm in the southern part of the Chiloé island. The best fitting fault model shows a pure thrust-fault motion on a shallow dipping plane orienting 4° NNE. The InSAR-determined moment is 2.4 × 1020 Nm with a shear modulus of 30 GPa, equivalent to Mw 7.56, which is slightly lower than the seismic moment. The model shows that the slip did not reach the trench, and it reruptured part of the fault that ruptured in the 1960 Mw 9.5 earthquake. The 2016 event has only released a small portion of the accumulated strain energy on the 1960 rupture zone, suggesting that the seismic hazard of future great earthquakes in southern Chile is high.

Versatile generation of optical vector fields and vector beams using a non-interferometric approach.

Science.gov (United States)

Tripathi, Santosh; Toussaint, Kimani C

2012-05-07

We present a versatile, non-interferometric method for generating vector fields and vector beams which can produce all the states of polarization represented on a higher-order Poincaré sphere. The versatility and non-interferometric nature of this method is expected to enable exploration of various exotic properties of vector fields and vector beams. To illustrate this, we study the propagation properties of some vector fields and find that, in general, propagation alters both their intensity and polarization distribution, and more interestingly, converts some vector fields into vector beams. In the article, we also suggest a modified Jones vector formalism to represent vector fields and vector beams.

History of surface displacements at the Yellowstone Caldera, Wyoming, from leveling surveys and InSAR observations, 1923-2008

Science.gov (United States)

Dzurisin, Daniel; Wicks, Charles W.; Poland, Michael P.

2012-01-01

Modern geodetic studies of the Yellowstone caldera, Wyoming, and its extraordinary tectonic, magmatic, and hydrothermal systems date from an initial leveling survey done throughout Yellowstone National Park in 1923 by the U.S. Coast and Geodetic Survey. A repeat park-wide survey by the U.S. Geological Survey (USGS) and the University of Utah during 1975-77 revealed that the central part of the caldera floor had risen more than 700 mm since 1923, at an average rate of 14±1 mm/yr. From 1983 to 2007, the USGS conducted 15 smaller surveys of a single level line that crosses the northeast part of the caldera, including the area where the greatest uplift had occurred from 1923 to 1975-77. The 1983 and 1984 surveys showed that uplift had continued at an average rate of 22±1 mm/yr since 1975-77, but no additional uplift occurred during 1984-85 (-2±5 mm/yr), and during 1985-95 the area subsided at an average rate of 19±1 mm/yr. The change from uplift to subsidence was accompanied by an earthquake swarm, the largest ever recorded in the Yellowstone area (as of March 2012), starting in October 1985 and located near the northwest rim of the caldera. Interferometric synthetic aperture radar (InSAR) images showed that the area of greatest subsidence migrated from the northeast part of the caldera (including the Sour Creek resurgent dome) during 1992-93 to the southwest part (including the Mallard Lake resurgent dome) during 1993-95. Thereafter, uplift resumed in the northeast part of the caldera during 1995-96, while subsidence continued in the southwest part. The onset of uplift migrated southwestward, and by mid-1997, uplift was occurring throughout the entire caldera (essentially rim to rim, including both domes). Consistent with these InSAR observations, leveling surveys indicated 24±3 mm of uplift in the northeast part of the caldera during 1995-98. The beginning of uplift was coincident with or followed shortly after an earthquake swarm near the north caldera rim

A novel lightweight Fizeau infrared interferometric imaging system

Science.gov (United States)

Hope, Douglas A.; Hart, Michael; Warner, Steve; Durney, Oli; Romeo, Robert

2016-05-01

Aperture synthesis imaging techniques using an interferometer provide a means to achieve imagery with spatial resolution equivalent to a conventional filled aperture telescope at a significantly reduced size, weight and cost, an important implication for air- and space-borne persistent observing platforms. These concepts have been realized in SIRII (Space-based IR-imaging interferometer), a new light-weight, compact SWIR and MWIR imaging interferometer designed for space-based surveillance. The sensor design is configured as a six-element Fizeau interferometer; it is scalable, light-weight, and uses structural components and main optics made of carbon fiber replicated polymer (CFRP) that are easy to fabricate and inexpensive. A three-element prototype of the SIRII imager has been constructed. The optics, detectors, and interferometric signal processing principles draw on experience developed in ground-based astronomical applications designed to yield the highest sensitivity and resolution with cost-effective optical solutions. SIRII is being designed for technical intelligence from geo-stationary orbit. It has an instantaneous 6 x 6 mrad FOV and the ability to rapidly scan a 6x6 deg FOV, with a minimal SNR. The interferometric design can be scaled to larger equivalent filled aperture, while minimizing weight and costs when compared to a filled aperture telescope with equivalent resolution. This scalability in SIRII allows it address a range of IR-imaging scenarios.

Evaluation of the SBAS InSAR Service of the European Space Agency’s Geohazard Exploitation Platform (GEP

Directory of Open Access Journals (Sweden)

Jorge Pedro Galve

2017-12-01

Full Text Available The analysis of remote sensing data to assess geohazards is being improved by web-based platforms and collaborative projects, such as the Geohazard Exploitation Platform (GEP of the European Space Agency (ESA. This paper presents the evaluation of a surface velocity map that is generated by this platform. The map was produced through an unsupervised Multi-temporal InSAR (MTI analysis applying the Parallel-SBAS (P-SBAS algorithm to 25 ENVISAT satellite images from the South of Spain that were acquired between 2003 and 2008. This analysis was carried out using a service implemented in the GEP called “SBAS InSAR”. Thanks to the map that was generated by the SBAS InSAR service, we identified processes not documented so far; provided new monitoring data in places affected by known ground instabilities; defined the area affected by these instabilities; and, studied a case where GEP could have been able to help in the forecast of a slope movement reactivation. This amply demonstrates the reliability and usefulness of the GEP, and shows how web-based platforms may enhance the capacity to identify, monitor, and assess hazards that are associated to geological processes.

Contrast computation methods for interferometric measurement of sensor modulation transfer function

Science.gov (United States)

Battula, Tharun; Georgiev, Todor; Gille, Jennifer; Goma, Sergio

2018-01-01

Accurate measurement of image-sensor frequency response over a wide range of spatial frequencies is very important for analyzing pixel array characteristics, such as modulation transfer function (MTF), crosstalk, and active pixel shape. Such analysis is especially significant in computational photography for the purposes of deconvolution, multi-image superresolution, and improved light-field capture. We use a lensless interferometric setup that produces high-quality fringes for measuring MTF over a wide range of frequencies (here, 37 to 434 line pairs per mm). We discuss the theoretical framework, involving Michelson and Fourier contrast measurement of the MTF, addressing phase alignment problems using a moiré pattern. We solidify the definition of Fourier contrast mathematically and compare it to Michelson contrast. Our interferometric measurement method shows high detail in the MTF, especially at high frequencies (above Nyquist frequency). We are able to estimate active pixel size and pixel pitch from measurements. We compare both simulation and experimental MTF results to a lens-free slanted-edge implementation using commercial software.

New orbital elements of 5 interferometric double stars

Directory of Open Access Journals (Sweden)

Olević D.

1999-01-01

Full Text Available In this paper, for the first time, are presented elliptical and Thiel- Innes orbitatal elements for the following interferometric pairs: WDS 00416+2438 = WRH, WDS 03271+1845 = CHARA 10, WDS 04044+2406 = McA 13 Aa, WDS 17095+4047 = McA 45 and WDS 23019+4219 = o And Aa. For the pairs WDS 03271+1845 = CHARA 10 andWDS 04044+2406 = McA 13 Aa are calculated total masses and dynamical parallaxes which are compared with corresponding Hipparcos parallaxes.

Mitigation of defocusing by statics and near-surface velocity errors by interferometric least-squares migration with a reference datum

KAUST Repository

Sinha, Mrinal

2016-05-23

Imaging seismic data with an erroneous migration velocity can lead to defocused migration images. To mitigate this problem, we first choose a reference reflector whose topography is well-known from the well logs, for example. Reflections from this reference layer are correlated with the traces associated with reflections from deeper interfaces to get crosscorrelograms. Interferometric least-squares migration (ILSM) is then used to get the migration image that maximizes the crosscorrelation between the observed and the predicted crosscorrelograms. Deeper reference reflectors are used to image deeper parts of the subsurface with a greater accuracy. Results on synthetic and field data show that defocusing caused by velocity errors is largely suppressed by ILSM. We have also determined that ILSM can be used for 4D surveys in which environmental conditions and acquisition parameters are significantly different from one survey to the next. The limitations of ILSM are that it requires prior knowledge of a reference reflector in the subsurface and the velocity model below the reference reflector should be accurate.

Matterwave interferometric velocimetry of cold Rb atoms

Science.gov (United States)

Carey, Max; Belal, Mohammad; Himsworth, Matthew; Bateman, James; Freegarde, Tim

2018-03-01

We consider the matterwave interferometric measurement of atomic velocities, which forms a building block for all matterwave inertial measurements. A theoretical analysis, addressing both the laboratory and atomic frames and accounting for residual Doppler sensitivity in the beamsplitter and recombiner pulses, is followed by an experimental demonstration, with measurements of the velocity distribution within a 20 ?K cloud of rubidium atoms. Our experiments use Raman transitions between the long-lived ground hyperfine states, and allow quadrature measurements that yield the full complex interferometer signal and hence discriminate between positive and negative velocities. The technique is most suitable for measurement of colder samples.

Long-term contraction of pyroclastic flow deposits at Augustine Volcano using InSAR

Science.gov (United States)

McAlpin, D. B.; Meyer, F. J.; Lu, Z.; Beget, J. E.

2013-12-01

Augustine Island is a small, 8x11 km island in South Central Alaska's lower Cook Inlet. It is approximately 280 km southwest of Anchorage, and occupied entirely by its namesake Augustine Volcano. The volcano's nearly symmetrical central cone reaches an altitude of 1260 m, and the surrounding island is composed almost entirely of volcanic deposits. It is the youngest and most frequently active volcano in the lower Cook Inlet, with at least seven known eruptions since the beginning of written records in 1812. Its two most recent eruptions occurred during March-August 1986, and January-March 2006 The 1986 and 2006 Augustine eruptions produced significant pyroclastic flow deposits (PFDs) on the island, both which have been well mapped by previous studies. Subsidence of material deposited by these pyroclastic flows has been measured by InSAR data, and can be attributed to at least four processes: (1) initial, granular settling; (2) thermal contraction; (3) loading of 1986 PFDs from overlying 2006 deposits; and (4) continuing subsidence of 1986 PFDs buried beneath 2006 flows. For this paper, SAR data for PFDs from Augustine Volcano were obtained from 1992 through 2005, from 2006-2007, and from 2007-2011. These time frames provided InSAR data for long-term periods after both 1986 and 2006 eruptions. From time-series analysis of these datasets, deformation rates of 1986 PFDs and 2006 PFDs were determined, and corrections applied where newer deposits were emplaced over old deposits. The combination of data sets analyzed in this study enabled, for the first time, an analysis of long and short term subsidence rates of volcanic deposits emplaced by the two eruptive episodes. The generated deformation time series provides insight into the significance and duration of the initial settling period and allows us to study the thermal regime and heat loss of the PFDs. To extract quantitative information about thermal properties and composition of the PFDs, we measured the thickness

Monitoring of Three Case Studies of Creeping Landslides in Ecuador using L-band SAR Interferometry (InSAR)

Science.gov (United States)

Mayorga Torres, T. M.; Mohseni Aref, M.

2015-12-01

Tannia Mayorga Torres1,21 Universidad Central del Ecuador. Faculty of Geology, Mining, Oil, and Environment 2 Hubert H. Humphrey Fellowship 2015-16 IntroductionLandslides lead to human and economic losses across the country, mainly in the winter season. On the other hand, satellite radar data has cost-effective benefits due to open-source software and free availability of data. With the purpose of establishing an early warning system of landslide-related surface deformation, three case studies were designed in the Coast, Sierra (Andean), and Oriente (jungle) regions. The objective of this work was to assess the capability of L-band InSAR to get phase information. For the calculation of the interferograms in Repeat Orbit Interferometry PACkage, the displacement was detected as the error and was corrected. The coherence images (Figure 1) determined that L-band is suitable for InSAR processing. Under this frame, as a first approach, the stacking DInSAR technique [1] was applied in the case studies [2]; however, due to lush vegetation and steep topography, it is necessary to apply advanced InSAR techniques [3]. The purpose of the research is to determine a pattern of data acquisition and successful results to understand the spatial and temporal ground movements associated with landslides. The further work consists of establishing landslide inventories to combine phases of SAR images to generate maps of surface deformation in Tumba-San Francisco and Guarumales to compare the results with ground-based measurements to determine the maps' accuracy. References[1] Sandwell D., Price E. (1998). Phase gradient approach to stacking interferograms. Journal of Geophysical Research, Vol. 103, N. B12, pp. 30,183-30,204. [2] Mayorga T., Platzeck G. (2014). Using DInSAR as a tool to detect unstable terrain areas in an Andes region in Ecuador. NH3.5-Blue Poster B298, Vol. 16, EGU2014-16203. Austria. [3] Wasowski J., Bovenga F. (2014). Investigating landslides and unstable slopes with

Coherent laser radar with dual-frequency Doppler estimation and interferometric range detection

NARCIS (Netherlands)

Onori, D.; Scotti, F.; Laghezza, F.; Scaffardi, M.; Bogoni, A.

2016-01-01

The concept of a coherent interferometric dual frequency laser radar, that measures both the target range and velocity, is presented and experimentally demonstrated. The innovative architecture combines the dual frequency lidar concept, allowing a precise and robust Doppler estimation, with the

The second order extended Kalman filter and Markov nonlinear filter for data processing in interferometric systems

International Nuclear Information System (INIS)

Ermolaev, P; Volynsky, M

2014-01-01

Recurrent stochastic data processing algorithms using representation of interferometric signal as output of a dynamic system, which state is described by vector of parameters, in some cases are more effective, compared with conventional algorithms. Interferometric signals depend on phase nonlinearly. Consequently it is expedient to apply algorithms of nonlinear stochastic filtering, such as Kalman type filters. An application of the second order extended Kalman filter and Markov nonlinear filter that allows to minimize estimation error is described. Experimental results of signals processing are illustrated. Comparison of the algorithms is presented and discussed.

Effect of energy deposited by cosmic-ray particles on interferometric gravitational wave detectors

International Nuclear Information System (INIS)

Yamamoto, Kazuhiro; Hayakawa, Hideaki; Okada, Atsushi; Uchiyama, Takashi; Miyoki, Shinji; Ohashi, Masatake; Kuroda, Kazuaki; Kanda, Nobuyuki; Tatsumi, Daisuke; Tsunesada, Yoshiki

2008-01-01

We investigated the noise of interferometric gravitational wave detectors due to heat energy deposited by cosmic-ray particles. We derived a general formula that describes the response of a mirror against a cosmic-ray passage. We found that there are differences in the comic-ray responses (the dependence of temperature and cosmic-ray track position) in cases of interferometric and resonant gravitational wave detectors. The power spectral density of vibrations caused by low-energy secondary muons is 100 times smaller than the goal sensitivity of future second-generation interferometer projects, such as LCGT and Advanced LIGO. The arrival frequency of high-energy cosmic-ray muons that generate enough large showers inside mirrors of LCGT and Advanced LIGO is one per a millennium. We also discuss the probability of exotic-particle detection with interferometers.

Laser amplitude stabilization for advanced interferometric gravitational wave detectors

International Nuclear Information System (INIS)

Barr, B W; Strain, K A; Killow, C J

2005-01-01

We present results of experiments into the stabilization of the amplitude of Nd:YAG lasers for use in advanced gravitational wave detectors. By feeding back directly to the pump-diode driving current we achieved shot-noise-limited stabilization at frequencies up to several kHz with some residual noise at lower frequencies (sub ∼100 Hz). The method used is applicable to higher powered laser systems planned for advanced interferometric gravitational wave detectors

Quantum dot-based local field imaging reveals plasmon-based interferometric logic in silver nanowire networks.

Science.gov (United States)

Wei, Hong; Li, Zhipeng; Tian, Xiaorui; Wang, Zhuoxian; Cong, Fengzi; Liu, Ning; Zhang, Shunping; Nordlander, Peter; Halas, Naomi J; Xu, Hongxing

2011-02-09

We show that the local electric field distribution of propagating plasmons along silver nanowires can be imaged by coating the nanowires with a layer of quantum dots, held off the surface of the nanowire by a nanoscale dielectric spacer layer. In simple networks of silver nanowires with two optical inputs, control of the optical polarization and phase of the input fields directs the guided waves to a specific nanowire output. The QD-luminescent images of these structures reveal that a complete family of phase-dependent, interferometric logic functions can be performed on these simple networks. These results show the potential for plasmonic waveguides to support compact interferometric logic operations.

Ground Subsidence over Beijing-Tianjin-Hebei Region during Three Periods of 1992 to 2014 Monitored by Interferometric SAR

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ZHANG Yonghong

2016-09-01

Full Text Available The Beijing-Tianjin-Hebei region suffers the most serious ground subsidence in China, which has caused huge economic losses every year. Therefore, ground subsidence was listed as an important mission in the project of geographic conditions monitoring over Beijing-Tianjin-Hebei launched by the National Administration of Surveying, Mapping and Geoinformation in 2013. In this paper, we propose a methodology of ground subsidence monitoring over wide area, which is entitled "multiple master-image coherent target small-baseline interferometric SAR (MCTSB-InSAR". MCTSB-InSAR is an improved time series InSAR technique with some unique features. SAR datasets used for ground subsidence monitoring over the Beijing-Tianjin-Hebei region include ERS-1/2 SAR images acquired between 1992 to 2000, ENVISAT ASAR images acquired between 2003 to 2010 and RADARSAT-2 images acquired between 2012 to 2014. This research represents a first ever effort on mapping ground subsidence over Beijing-Tianjin-Hebei region and over such as a long time span in China. In comparison with more than 120 leveling measurements collected in Beijing and Tianjin, the derived subsidence velocity has the accuracy of 8.7mm/year (1992—2000, 4.7mm/year (2003—2010, and 5.4mm/year (2012—2014 respectively. The spatial-temporal characteristics of the development of ground subsidence in Beijing and Tianjin are analyzed. In general, ground subsidence in Beijing kept continuously expanding in the period of 1992 to 2014. While, ground subsidence in Tianjin had already been serious in 1990s, had dramatically expanded during 2000s, and started to alleviate in recent years. The monitoring result is of high significance for prevention and mitigation of ground subsidence disaster, for making development plan, for efficient and effective utilization of water resource, and for adjustment of economic framework of this region. The result also indicates the effectiveness and reliability of the MCTSB

Large-Area Landslides Monitoring Using Advanced Multi-Temporal InSAR Technique over the Giant Panda Habitat, Sichuan, China

Directory of Open Access Journals (Sweden)

Panpan Tang

2015-07-01

Full Text Available The region near Dujiangyan City and Wenchuan County, Sichuan China, including significant giant panda habitats, was severely impacted by the Wenchuan earthquake. Large-area landslides occurred and seriously threatened the lives of people and giant pandas. In this paper, we report the development of an enhanced multi-temporal interferometric synthetic aperture radar (MTInSAR methodology to monitor potential post-seismic landslides by analyzing coherent scatterers (CS and distributed scatterers (DS points extracted from multi-temporal l-band ALOS/PALSAR data in an integrated manner. Through the integration of phase optimization and mitigation of the orbit and topography-related phase errors, surface deformations in the study area were derived: the rates in the line of sight (LOS direction ranged from −7 to 1.5 cm/a. Dozens of potential landslides, distributed mainly along the Minjiang River, Longmenshan Fault, and in other the high-altitude areas were detected. These findings matched the distribution of previous landslides. InSAR-derived results demonstrated that some previous landslides were still active; many unstable slopes have developed, and there are significant probabilities of future massive failures. The impact of landslides on the giant panda habitat, however ranged from low to moderate, would continue to be a concern for conservationists for some time in the future.

Synthetic biology, inspired by synthetic chemistry.

Science.gov (United States)

Malinova, V; Nallani, M; Meier, W P; Sinner, E K

2012-07-16

The topic synthetic biology appears still as an 'empty basket to be filled'. However, there is already plenty of claims and visions, as well as convincing research strategies about the theme of synthetic biology. First of all, synthetic biology seems to be about the engineering of biology - about bottom-up and top-down approaches, compromising complexity versus stability of artificial architectures, relevant in biology. Synthetic biology accounts for heterogeneous approaches towards minimal and even artificial life, the engineering of biochemical pathways on the organismic level, the modelling of molecular processes and finally, the combination of synthetic with nature-derived materials and architectural concepts, such as a cellular membrane. Still, synthetic biology is a discipline, which embraces interdisciplinary attempts in order to have a profound, scientific base to enable the re-design of nature and to compose architectures and processes with man-made matter. We like to give an overview about the developments in the field of synthetic biology, regarding polymer-based analogs of cellular membranes and what questions can be answered by applying synthetic polymer science towards the smallest unit in life, namely a cell. Copyright © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Visibility-based angular power spectrum estimation in low-frequency radio interferometric observations

NARCIS (Netherlands)

Choudhuri, Samir; Bharadwaj, Somnath; Ghosh, Abhik; Ali, Sk. Saiyad

2014-01-01

We present two estimators to quantify the angular power spectrum of the sky signal directly from the visibilities measured in radio interferometric observations. This is relevant for both the foregrounds and the cosmological 21-cm signal buried therein. The discussion here is restricted to the

Localized surface disruptions observed by InSAR during strong earthquakes in Java and Hawai'i

Science.gov (United States)

Poland, M.

2010-01-01

Interferometric Synthetic Aperture Radar data spanning strong earthquakes on the islands of Java and Hawai‘i in 2006 reveal patches of subsidence and incoherence indicative of localized ground failure. Interferograms spanning the 26 May 2006 Java earthquake suggest an area of about 7.5 km2 of subsidence (~2 cm) and incoherence south of the city of Yogyakarta that correlates with significant damage to housing, high modeled peak ground accelerations, and poorly consolidated geologic deposits. The subsidence and incoherence is inferred to be a result of intense shaking and/or damage. At least five subsidence patches on the west side of the Island of Hawai‘i, ranging 0.3–2.2 km2 in area and 3–8 cm in magnitude, occurred as a result of a pair of strong earthquakes on 15 October 2006. Although no felt reports or seismic data are available from the areas in Hawai‘i, the Java example suggests that the subsidence patches indicate areas of amplified earthquake shaking. Surprisingly, all subsidence areas in Hawai‘i were limited to recent, and supposedly stable, lava flows and may reflect geological conditions not detectable at the surface. In addition, two ‘a‘ā lava flows in Hawai‘i were partially incoherent in interferograms spanning the earthquakes, indicating surface disruption as a result of the earthquake shaking. Coearthquake incoherence of rubbly deposits, like ‘a‘ā flows, should be explored as a potential indicator of earthquake intensity and past strong seismic activity.

Interferometric control of the photon-number distribution

Directory of Open Access Journals (Sweden)

H. Esat Kondakci

2017-07-01

Full Text Available We demonstrate deterministic control over the photon-number distribution by interfering two coherent beams within a disordered photonic lattice. By sweeping a relative phase between two equal-amplitude coherent fields with Poissonian statistics that excite adjacent sites in a lattice endowed with disorder-immune chiral symmetry, we measure an output photon-number distribution that changes periodically between super-thermal and sub-thermal photon statistics upon ensemble averaging. Thus, the photon-bunching level is controlled interferometrically at a fixed mean photon-number by gradually activating the excitation symmetry of the chiral-mode pairs with structured coherent illumination and without modifying the disorder level of the random system itself.

Geodetic observations and modeling of magmatic inflation at the Three Sisters volcanic center, central Oregon Cascade Range, USA

Science.gov (United States)

Dzurisin, Daniel; Lisowski, Michael; Wicks, Charles W.; Poland, Michael P.; Endo, Elliot T.

2006-02-01

Tumescence at the Three Sisters volcanic center began sometime between summer 1996 and summer 1998 and was discovered in April 2001 using interferometric synthetic aperture radar (InSAR). Swelling is centered about 5 km west of the summit of South Sister, a composite basaltic-andesite to rhyolite volcano that last erupted between 2200 and 2000 yr ago, and it affects an area ˜20 km in diameter within the Three Sisters Wilderness. Yearly InSAR observations show that the average maximum displacement rate was 3-5 cm/yr through summer 2001, and the velocity of a continuous GPS station within the deforming area was essentially constant from June 2001 to June 2004. The background level of seismic activity has been low, suggesting that temperatures in the source region are high enough or the strain rate has been low enough to favor plastic deformation over brittle failure. A swarm of about 300 small earthquakes ( Mmax = 1.9) in the northeast quadrant of the deforming area on March 23-26, 2004, was the first notable seismicity in the area for at least two decades. The U.S. Geological Survey (USGS) established tilt-leveling and EDM networks at South Sister in 1985-1986, resurveyed them in 2001, the latter with GPS, and extended them to cover more of the deforming area. The 2001 tilt-leveling results are consistent with the inference drawn from InSAR that the current deformation episode did not start before 1996, i.e., the amount of deformation during 1995-2001 from InSAR fully accounts for the net tilt at South Sister during 1985-2001 from tilt-leveling. Subsequent InSAR, GPS, and leveling observations constrain the source location, geometry, and inflation rate as a function of time. A best-fit source model derived from simultaneous inversion of all three datasets is a dipping sill located 6.5 ± 2.5 km below the surface with a volume increase of 5.0 × 10 6 ± 1.5 × 10 6 m 3/yr (95% confidence limits). The most likely cause of tumescence is a pulse of basaltic magma

Measurement of Seaward Ground Displacements on Coastal Landfill Area Using Radar Interferometry

Science.gov (United States)

Baek, W.-K.; Jung, H.-S.

2018-04-01

In order to understand the mechanism of subsidence and help reducing damage, researchers has been observed the line-of-sight subsidence on the Noksan industrial complex using SAR Interferometry(InSAR) and suggested subsidence prediction models. Although these researches explained a spatially uneven ground subsidence near the seaside, they could not have been explained the occurrence of the newly proposed seaward horizontal, especially nearly north-ward, displacement because of the geometric limitation of InSAR measurements. In this study, we measured the seaward ground displacements trend on the coastal landfill area, Noksan Industrial Complex. We set the interferometric pairs from an ascending and a descending orbits strip map data of ALOS PALSAR2. We employed InSAR and MAI stacking approaches for the both orbits respectively in order to improve the measurement. Finally, seaward deformation was estimated by retrieving three-dimensional displacements from multi-geometric displacements. As a results, maximally 3.3 and 0.7 cm/year of ground displacements for the vertical and seaward directions. In further study, we plan to generate InSAR and MAI stacking measurements with additional SAR data to mitigate tropospheric effect and noise well. Such a seaward observation approach using spaceborne radar is expected to be effective in observing the long-term movements on coastal landfill area.

InSAR observations of low slip rates on the major faults of western Tibet.

Science.gov (United States)

Wright, Tim J; Parsons, Barry; England, Philip C; Fielding, Eric J

2004-07-09

Two contrasting views of the active deformation of Asia dominate the debate about how continents deform: (i) The deformation is primarily localized on major faults separating crustal blocks or (ii) deformation is distributed throughout the continental lithosphere. In the first model, western Tibet is being extruded eastward between the major faults bounding the region. Surface displacement measurements across the western Tibetan plateau using satellite radar interferometry (InSAR) indicate that slip rates on the Karakoram and Altyn Tagh faults are lower than would be expected for the extrusion model and suggest a significant amount of internal deformation in Tibet.

Effect of Medium Symmetries in Limiting the Number of Parameters Estimated with Polarimetric Interferometry

Science.gov (United States)

Moghaddam, Mahta

2000-01-01

The addition of interferometric backscattering pairs to the conventional polarimetric SAR data over forests and other vegetated areas increases the dimensionality of the data space, in principle enabling the estimation of a larger number of vegetation parameters. Without regard to the sensitivity of these data to vegetation scattering parameters, this paper poses the question: Will increasing the data channels as such result in a one-to-one increase in the number of parameters that can be estimated, or do vegetation and data properties inherently limit that number otherwise? In this paper, the complete polarimetric interferometric covariance matrix is considered and various symmetry properties of the scattering medium are used to study whether any of the correlation pairs can be eliminated. The number of independent pairs has direct consequences in their utility in parameter estimation schemes, since the maximum number of parameters that can be estimated cannot exceed the number of unique measurements. The independent components of the polarimetric interferometric SAR (POL/INSAR) data are derived for media with reflection, rotation, and azimuth symmetries, which are often encountered in vegetated surfaces. Similar derivations have been carried out before for simple polarimetry, i.e., zero baseline. This paper extends those to the interferometric case of general nonzero baselines. It is shown that depending on the type of symmetries present, the number of independent available measurements that can be used to estimate medium parameters will vary. In particular, whereas in the general case there are 27 mathematically independent measurements possible from a polarimetric interferometer, this number can be reduced to 15, 9, and 6 if the medium has reflection, rotation, or azimuthal symmetries, respectively. The results can be used in several ways in the interpretation of SAR data and the development of parameter estimation schemes, which will be discussed at the

Repeat-Pass Multi-Temporal Interferometric SAR Coherence Variations with Amazon Floodplain and Lake Habitats

Science.gov (United States)

Jung, H.; Alsdorf, D.

2006-12-01

Monitoring discharge in the main channels of rivers and upland tributaries as well as storage changes in floodplain lakes is necessary for understanding flooding hazards, methane production, sediment transport, and nutrient exchange. Interferometric processing of synthetic aperture radar (SAR) data may enable hydrologists to detect environmental and ecological changes in hydrological systems over space and time. An aim of our experiments is to characterize interferometric SAR coherence variations that occur in Amazon aquatic habitats. We analyze coherence variations in JERS-1 data at three central Amazon sites; Lake Balbina, the Cabaliana floodplain, and the confluence of the Purus and Amazon rivers. Because radar pulse interactions with inundated vegetation typically follow a double-bounce travel path which returns energy to the antenna, coherence will vary with vegetation type, physical baseline, and temporal baseline. Balbina's vegetation consists mostly of forest and inundated trunks of dead, leafless trees as opposed to Cabaliana and Amazon- Purus (dominated by flooded forests), thus it serves to isolate the vegetation signal. Coherence variations with baselines were determined from 253 interferograms at Balbina, 210 at Calbaliana, and 153 at Purus. The average temporal and perpendicular baselines (mean std.) are 574 394 days and 1708 1159 m at Balbina, 637 435 days and 1381 981 m at Cabaliana, and 587 425 days and 1430 964 m at Purus. Balbina has a stronger coherence than either Cabaliana or Amazon-Purus. With results of Mann-Whitney statistical tests, Balbina has a difference between terre-firme and flooded coherence values plotted with perpendicular baseline but Cabaliana and Amazon-Purus do not show this difference. Balbina has a linearly decreasing trend in coherence plotted with temporal baseline whereas Cabaliana and Amazon-Purus have a steep drop-off, non- linear change. A strong annual periodicity is evident on power spectrums of the coherence values

Measurement of long-term land subsidence by combination of InSAR and time series analysis - Application study to Kanto Plains of Japan -

Science.gov (United States)

Deguchi, T.; Rokugawa, S.; Matsushima, J.

2009-04-01

InSAR is an application technique of synthetic aperture radars and is now drawing attention as a methodology capable of measuring subtle surface deformation over a wide area with a high spatial resolution. In this study, the authors applied the method of measuring long-term land subsidence by combining InSAR and time series analysis to Kanto Plains of Japan using 28 images of ENVISAT/ASAR data. In this measuring method, the value of land deformation is set as an unknown parameter and the optimal solution to the land deformation amount is derived by applying a smoothness-constrained inversion algorithm. The vicinity of the Kanto Plain started to subside in the 1910s, and became exposed to extreme land subsidence supposedly in accordance with the reconstruction efforts after the Second World War and the economic development activities. The main causes of the land subsidence include the intake of underground water for the use in industries, agriculture, waterworks, and other fields. In the Kujukuri area, the exploitation of soluble natural gas also counts. The Ministry of Environment reported in its documents created in fiscal 2006 that a total of 214 km2 in Tokyo and the six prefectures around the Plain had undergone a subsidence of 1 cm or more per a year. As a result of long-term land subsidence over approximately five and a half years from 13th January, 2003, to 30th June, 2008, unambiguous land deformation was detected in six areas: (i) Haneda Airport, (ii) Urayasu City, (iii) Kasukabe-Koshigaya, (iv) Southern Kanagawa, (v) Toride-Ryugasaki, and (vi) Kujukuri in Chiba Prefecture. In particular, the results for the Kujukuri area were compared with the leveling data taken around the same area to verify the measuring accuracy. The comparative study revealed that the regression formula between the results obtained by time series analysis and those by the leveling can be expressed as a straight line with a gradient of approximately 1, though including a bias of about

Ultra-Low Noise Quad Photoreceiver for Space Based Laser Interferometric Gravity Wave Detection, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Gravity wave detection using space-based long-baseline laser interferometric sensors imposes stringent noise requirements on the system components, including the...

Imaging Stars by Performing Full-Stokes Optical Interferometric Polarimetry

Directory of Open Access Journals (Sweden)

Nicholas M. Elias II

2012-03-01

Full Text Available Optical interferometry and polarimetry have separately provided new insights into stellar astronomy, especially in the fields of fundamental parameters and atmospheric models. We present: scientific justifications for “full-Stokes” optical interferometric polarimetry (OIP; updated instrument requirements; preliminary beam combiner designs; polarimeter design; end-to-end OIP data reduction; and realistic reimaged full-Stokes models of Be stars with a suitable number of telescopes plus noise sources. All of this work represents preliminary research to construct an OIP beam combiner.

Sentinel-1 observation of the 2017 Sangsefid earthquake, northeastern Iran: Rupture of a blind reserve-slip fault near the Eastern Kopeh Dagh

Science.gov (United States)

Xu, Guangyu; Xu, Caijun; Wen, Yangmao

2018-04-01

New satellites are now revealing InSAR-based surface deformation within a week after natural hazard events. Quick hazard responses will be more publically accessible and provide information to responding agencies. Here we used Sentinel-1 interferometric synthetic aperture radar (InSAR) data to investigate coseismic deformation associated with the 2017 Sangsefid earthquake, which occurred in the southeast margin of the Kopeh Dagh fault system. The ascending and descending interferograms indicate thrust-dominated slip, with the maximum line-of-sight displacement of 10.5 and 13.7 cm, respectively. The detailed slip-distribution of the 2017 Sangsefid Mw6.1 earthquake inferred from geodetic data is presented here for the first time. Although the InSAR interferograms themselves do not uniquely constrain what the primary slip surface is, we infer that the source fault dips to southwest by analyzing the 2.5 D displacement field decomposed from the InSAR observations. The determined uniform slip fault model shows that the dip angle of the seimogenic fault is approximately 40°, with a strike of 120° except for a narrower fault width than that predicted by the empirical scaling law. We suggest that geometric complexities near the Kopeh Dagh fault system obstruct the rupture propagation, resulting in high slip occurred within a small area and much higher stress drop than global estimates. The InSAR-determined moment is 1.71 × 1018 Nm with a shear modulus of 3.32 × 1010 N/m2, equivalent to Mw 6.12, which is consistent with seismological results. The finite fault model (the west-dipping fault plane) reveals that the peak slip of 0.90 m occurred at a depth of 6.3 km, with substantial slip at a depth of 4-10 km and a near-uniform slip of 0.1 m at a depth of 0-2.5 km. We suggest that the Sangsefid earthquake occurred on an unknown blind reverse fault dipping southwest, which can also be recognised through observing the long-term surface effects due to the existence of the blind

Dynamic measurements of flowing cells labeled by gold nanoparticles using full-field photothermal interferometric imaging

Science.gov (United States)

Turko, Nir A.; Roitshtain, Darina; Blum, Omry; Kemper, Björn; Shaked, Natan T.

2017-06-01

We present highly dynamic photothermal interferometric phase microscopy for quantitative, selective contrast imaging of live cells during flow. Gold nanoparticles can be biofunctionalized to bind to specific cells, and stimulated for local temperature increase due to plasmon resonance, causing a rapid change of the optical phase. These phase changes can be recorded by interferometric phase microscopy and analyzed to form an image of the binding sites of the nanoparticles in the cells, gaining molecular specificity. Since the nanoparticle excitation frequency might overlap with the sample dynamics frequencies, photothermal phase imaging was performed on stationary or slowly dynamic samples. Furthermore, the computational analysis of the photothermal signals is time consuming. This makes photothermal imaging unsuitable for applications requiring dynamic imaging or real-time analysis, such as analyzing and sorting cells during fast flow. To overcome these drawbacks, we utilized an external interferometric module and developed new algorithms, based on discrete Fourier transform variants, enabling fast analysis of photothermal signals in highly dynamic live cells. Due to the self-interference module, the cells are imaged with and without excitation in video-rate, effectively increasing signal-to-noise ratio. Our approach holds potential for using photothermal cell imaging and depletion in flow cytometry.

Geodetic integration of Sentinel-1A IW data using PSInSAR in Hungary

Science.gov (United States)

Farkas, Péter; Hevér, Renáta; Grenerczy, Gyula

2015-04-01

ESA's latest Synthetic Aperture Radar (SAR) mission Sentinel-1 is a huge step forward in SAR interferometry. With its default acquisition mode called the Interferometric Wide Swath Mode (IW) areas through all scales can be mapped with an excellent return time of 12 days (while only the Sentinel-1A is in orbit). Its operational data policy is also a novelty, it allows scientific users free and unlimited access to data. It implements a new type of ScanSAR mode called Terrain Observation with Progressive Scan (TOPS) SAR. It has the same resolution as ScanSAR but with better signal-to-noise ratio distribution. The bigger coverage is achieved by rotation of the antenna in the azimuth direction, therefore it requires very precise co-registration because even errors under a pixel accuracy can introduce azimuth phase variations caused by differences in Doppler-centroids. In our work we will summarize the benefits and the drawbacks of the IW mode. We would like to implement the processing chain of GAMMA Remote Sensing of such data for mapping surface motion with special attention to the co-registration step. Not only traditional InSAR but the advanced method of Persistent Scatterer InSAR (PSInSAR) will be performed and presented as well. PS coverage, along with coherence, is expected to be good due to the small perpendicular and temporal baselines. We would also like to integrate these measurements into national geodetic networks using common reference points. We have installed trihedral corner reflectors at some selected sites to aid precise collocation. Thus, we aim to demonstrate that Sentinel-1 can be effectively used for surface movement detection and monitoring and it can also provide valuable information for the improvement of our networks.

Linking space observations to volcano observatories in Latin America: Results from the CEOS DRM Volcano Pilot

Science.gov (United States)

Delgado, F.; Pritchard, M. E.; Biggs, J.; Arnold, D. W. D.; Poland, M. P.; Ebmeier, S. K.; Wauthier, C.; Wnuk, K.; Parker, A. L.; Amelug, F.; Sansosti, E.; Mothes, P. A.; Macedo, O.; Lara, L.; Zoffoli, S.; Aguilar, V.

2015-12-01

Within Latin American, about 315 volcanoes that have been active in the Holocene, but according to the United Nations Global Assessment of Risk 2015 report (GAR15) 202 of these volcanoes have no seismic, deformation or gas monitoring. Following the 2012 Santorini Report on satellite Earth Observation and Geohazards, the Committee on Earth Observation Satellites (CEOS) has developed a 3-year pilot project to demonstrate how satellite observations can be used to monitor large numbers of volcanoes cost-effectively, particularly in areas with scarce instrumentation and/or difficult access. The pilot aims to improve disaster risk management (DRM) by working directly with the volcano observatories that are governmentally responsible for volcano monitoring, and the project is possible thanks to data provided at no cost by international space agencies (ESA, CSA, ASI, DLR, JAXA, NASA, CNES). Here we highlight several examples of how satellite observations have been used by volcano observatories during the last 18 months to monitor volcanoes and respond to crises -- for example the 2013-2014 unrest episode at Cerro Negro/Chiles (Ecuador-Colombia border); the 2015 eruptions of Villarrica and Calbuco volcanoes, Chile; the 2013-present unrest and eruptions at Sabancaya and Ubinas volcanoes, Peru; the 2015 unrest at Guallatiri volcano, Chile; and the 2012-present rapid uplift at Cordon Caulle, Chile. Our primary tool is measurements of ground deformation made by Interferometric Synthetic Aperture Radar (InSAR) but thermal and outgassing data have been used in a few cases. InSAR data have helped to determine the alert level at these volcanoes, served as an independent check on ground sensors, guided the deployment of ground instruments, and aided situational awareness. We will describe several lessons learned about the type of data products and information that are most needed by the volcano observatories in different countries.

Differential subsidence in Mexico City and implications to its Collective Transport System (Metro).

Science.gov (United States)

Solano Rojas, D. E.; Wdowinski, S.; Cabral-Cano, E.; Osmanoglu, B.

2017-12-01

Mexico City is one of the fastest subsiding metropolis in the world. At displacement rates ranging from 0 to -380 [mm/yr], the complex geological setting is subjected to differential subsidence, which has led to damage, operation interruptions, and accidents to the Collective Transport System, or Metro. The Metro plays a critical role in Mexico City, carrying more than four million passengers per day. However, no previous study has focused on the deformation monitoring along the 93 km of the Metro surface railways, mainly because of the limitations of the traditional geodetic techniques. In this study, we use high-resolution Interferometric Synthetic Aperture Radar (InSAR) observations to monitor land subsidence throughout the city and quantify differential subsidence along surface Metro lines. Our analysis is based on 34 TerraSAR-X StripMap scenes acquired from May 2011 to June 2013 and 36 COSMO-SkyMed Stripmap scenes acquired from June 2011 to June 2012. The data were processed using the StaMPS InSAR time series technique, obtaining point densities of up to 4827 points/km2. Our post-processing methodologies include the following two components: (1) Detection of differential subsidence along the metro lines by calculating subsidence gradients, and (2) Detection of apparent uplift—areas subsiding slower than their surroundings—by using spatial frequency filtering. The two analyses allow us to recognize four main consequences of differential subsidence in the Metro system: 1. Deflection in elevated railways, 2. Deflection in street-level railways, 3. Columns with decreased loading capacity, and 4. Apparent uplift affecting surrounding infrastructure. Our results aim at shortening the large gap between scientific geodetic studies and applicable engineering parameters that can be used by local authorities in the city for maintenance and new lines development.

Evidences of Episodic Crustal Magmatic Diapir and Shallow Volcanic Activity at Uturuncu, Central Andes, from Geodetic Observations between 2014 - 2017

Science.gov (United States)

Lau, H. N.; Tymofyeyeva, E.; Fialko, Y. A.

2017-12-01

Previous space geodetic studies using ERS-1/2 and Envisat Interferometric Synthetic Aperture Radar (InSAR) data revealed a broad uplift of 10 mm/yr within the Altiplano-Puna Volcanic Complex (APVC), centered at the Uturuncu volcano, surrounded by a ring of subsidence at a rate of a few millimeters per year. This pattern was attributed to formation of a diapir in the middle of the Altiplano-Puna Magma Body (APMB), at depth of 15-19 km. We use new data from the Sentinel-1 InSAR mission, collected between 2014-2017, to produce high-resolution maps of surface displacements in the satellite's line of sight (LOS) from 4 satellite tracks. We estimated random propagation effects (e.g. due to atmospheric turbulence) using a common-point stacking method by Tymofyeyeva and Fialko [2015] and estimated temporally-correlated propagation effects (e.g. due to seasonal variations in atmospheric moisture) using a regression of the residual phase against topography. The estimated atmospheric artifacts were removed from the interferograms prior to computing the time series of the LOS displacements. The data indicate that the uplift above the APMB has considerably slowed down compared to the 1992-2010 epoch. The observed variations in the uplift rate suggest that the "ballooning" of the mid-crustal diapir is episodic on time scales of year to decades, possibly due to variations in melt supply from the partially molten APMB to the incipient diapir. We also find a previously undiscovered localized uplift 11 km south of Uturuncu's peak with maximum LOS velocities of 10 - 15 mm/yr. Joint inversions of data from different satellite tracks for a point source of inflation in an elastic half space constrain the source depth to be at 2 km, suggestive of a shallow magma chamber or a hydrothermal system.

Waste Management with Earth Observation Technologies

Science.gov (United States)

Margarit, Gerard; Tabasco, A.

2010-05-01

The range of applications where Earth Observation (EO) can be useful has been notably increased due to the maturity reached in the adopted technology and techniques. In most of the cases, EO provides a manner to remotely monitor particular variables and parameters with a more efficient usage of the available resources. Typical examples are environmental (forest, marine, resources…) monitoring, precision farming, security and surveillance (land, maritime…) and risk / disaster management (subsidence, volcanoes…). In this context, this paper presents a methodology to monitor waste disposal sites with EO. In particular, the explored technology is Interferometric Synthetic Aperture Radar (InSAR), which applies the interferometric concept to SAR images. SAR is an advanced radar concept able to acquire 2D coherent microwave reflectivity images for large scenes (tens of thousands kilometres) with fine resolution (case of waste management, InSAR has been used to evaluate the potentiality of EO to monitor the disposed volume along a specific range of time. This activity has been developed in collaboration with the Agència de Resídus de Catalunya (ARC) (The Waste Agency of Catalonia), Spain, in the framework of a pilot project. The motivation comes from the new law promoted by the regional Government that taxes the volume of disposed waste. This law put ARC in duty to control that the real volume matches the numbers provided by the waste processing firms so that they can not commit illegal actions. Right now, this task is performed with in-situ altimetry. But despite of the accurate results, this option is completely inefficient and limits the numbers of polls that can be generated and the number of waste sites that can be studied. As a consequence, the option to take profit of EO represents a good chance for ARC to improve the precision and quality of the monitoring tasks. This paper will present the methodology developed for monitoring waste sites as well as some

Landslide kinematics and their potential controls from hourly to decadal timescales: Insights from integrating ground-based InSAR measurements with structural maps and long-term monitoring data

Science.gov (United States)

Schulz, William H.; Coe, Jeffrey A.; Ricci, Pier P.; Smoczyk, Gregory M.; Shurtleff, Brett L.; Panosky, Joanna

2017-05-01

Knowledge of kinematics is rudimentary for understanding landslide controls and is increasingly valuable with greater spatiotemporal coverage. However, characterizing landslide-wide kinematics is rare, especially at broadly ranging timescales. We used highly detailed kinematic data obtained using photogrammetry and field mapping during the 1980s and 1990s and our 4.3-day ground-based InSAR survey during 2010 to study kinematics of the large, persistently moving Slumgullion landslide. The landslide was segregated into 11 kinematic elements using the 1980s-1990s data and the InSAR survey revealed most of these elements within a few hours. Averages of InSAR-derived displacement point measures within each element agreed well with higher quality in situ observations; averaging was deemed necessary because adverse look angles for the radar coupled with tree cover on the landslide introduced error in the InSAR results. We found that the landslide moved during 2010 at about half its 1985-1990 speed, but slowing was most pronounced at the landslide head. Gradually decreased precipitation and increased temperature between the periods likely resulted in lower groundwater levels and consequent slowing of the landslide. We used GPS survey results and limit-equilibrium modeling to analyze changing stability of the landslide head from observed thinning and found that its stability increased between the two periods, which would result in its slowing, and the consequent slowing of the entire landslide. Additionally, InSAR results suggested movement of kinematic element boundaries in the head region and our field mapping verified that they moved and changed character, likely because of the long-term increasing head stability. On an hourly basis, InSAR results were near error bounds but suggested landslide acceleration in response to seemingly negligible rainfall. Pore-pressure diffusion modeling suggested that rainfall infiltration affected frictional strength only to shallow depths

Non-Interferometric Tomography of Phase Objects Using Spatial Light Modulators

Directory of Open Access Journals (Sweden)

Thanh Nguyen

2016-10-01

Full Text Available Quantitative 3D phase retrieval techniques are based on either interferometric techniques such as holography or noninterferometric intensity-based techniques such as the transport of intensity equation (TIE. Interferometric techniques are vibration-sensitive and often use a reference beam requiring complicated optical alignment. In this work we develop a simple, fast, and noninterferometric tomographic 3D phase retrieval technique based on the TIE which does not suffer from such drawbacks. The optical setup is a modified 4f TIE system which uses an SLM to replace the slow translation of the CCD required to record several diffraction patterns in a traditional TIE system. This novel TIE setup is suitable for dynamical events such as imaging biological processes. A rotating mechanical stage is constructed to obtain tomographic phase images of the object. The tomographic reconstruction algorithm is based on the Fourier slice theorem (backprojection algorithm which applies to objects with a small refractive index span. Simulation and experimental results are shown as part of this work. A graphical user interface is developed to perform the TIE tomographic reconstruction algorithm and to synchronize the captured intensities by the CCD, the phase patterns displayed on the SLM, and the Arduino controlled rotating stage assembly.

Subsidence Monitoring in Seville (S Spain) Using Multi-Temporal InSAR

Science.gov (United States)

Ruiz-Armenteros, Antonio M.; Ruiz-Constan, Ana; Lamas-Fernandez, Francisco; Galindo-Zaldivar, Jesus; Sousa, Joaquim J.; Sanz de Galdeano, Carlos; Delgado, Manuel J.; Pedrera-Parias, Antonio; Martos-Rosillo, Sergio; Gil, Antonio J.; Caro-Cuenca, Miguel; Hanssen, Ramon F.

2016-08-01

Seville, with a metropolitan population of about 1.5 million, is the capital and largest city of Andalusia (S Spain). It is the 30th most populous municipality in the European Union and contains three UNESCO World Heritage Sites. The Seville harbour, located about 80 km from the Atlantic Ocean, is the only river port in Spain. The city is located on the plain of the Guadalquivir River. Using Multi-Temporal InSAR with ERS-1/2 and Envisat data a subsidence behavior is detected in the period 1992-2010. The geometry of the subsiding areas suggests that it should be conditioned by the fluvial dynamics of the Guadalquivir River and its tributaries. Facies distribution along the fluvial system (paleochannels, flood plains...), with different grain size and matrix proportion, may explain the relative subsidence between the different sectors.

Assessment of earthen levee stability for management and response: A NASA-DHS-California Dept. Water Resources collaboration

Science.gov (United States)

An, K.; Jones, C. E.; Bekaert, D. P.; Dudas, J.

2016-12-01

Radar remote sensing of the Sacramento-San Joaquin Delta, the largest estuary in the western U.S. (over 2500 km2), and its levee system provides an opportunity for NASA Applied Science to aid the CA Department of Water Resources (CA-DWR) in monitoring and emergency response. The delta contains over 1,500 km of earthen levees, supports about 2.5 million acres of agricultural land, and serves as a main water supply for 23 million California residents. Many of the reclaimed islands are 10-25 feet below sea level, sit atop compressible peat and organic clay soils, and are surrounded by levees only 1 foot above the once in a century flood elevation threshold. Land subsidence in the delta can be attributed to a variety of factors, including: aerobic oxidation of soils, soil compaction from drainage, wind erosion, anaerobic decomposition, dissolved carbon fluxes, floods, seismic events, and even rodent burrowing. Interferometric Synthetic Aperture Radar (InSAR) is an established technique to measure surface displacements and has been used to map large-scale subsidence. The demonstration of earthen levee monitoring is a recent development that has been greatly furthered by the emergence of new instruments such as NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR). UAVSAR is an L-band airborne sensor with high signal-to-noise ratio, repeat flight track accuracy, and has a high spatial resolution (7 x 7 m) that is necessary for detailed levee monitoring. The adaptability of radar instruments in their ability to see through smoke, haze, and clouds during the day or night, is especially relevant during disaster events, when cloud cover or lack of solar illumination inhibits traditional visual surveys of damage. We demonstrate the advantages of combining InSAR with geographic information systems (GIS) datasets in locating subsidence features along critical levee infrastructure in the Delta for 2009-2016. The ability to efficiently locate potential areas of

Analysis, comparison, and modeling of radar interferometry, date of surface deformation signals associated with underground explosions, mine collapses and earthquakes. Phase I: underground explosions, Nevada Test Site

International Nuclear Information System (INIS)

Foxall, W; Vincent, P; Walter, W

1999-01-01

We have previously presented simple elastic deformation modeling results for three classes of seismic events of concern in monitoring the CTBT-underground explosions, mine collapses and earthquakes. Those results explored the theoretical detectability of each event type using synthetic aperture radar interferometry (InSAR) based on commercially available satellite data. In those studies we identified and compared the characteristics of synthetic interferograms that distinguish each event type, as well the ability of the interferograms to constrain source parameters. These idealized modeling results, together with preliminary analysis of InSAR data for the 1995 mb 5.2 Solvay mine collapse in southwestern Wyoming, suggested that InSAR data used in conjunction with regional seismic monitoring holds great potential for CTBT discrimination and seismic source analysis, as well as providing accurate ground truth parameters for regional calibration events. In this paper we further examine the detectability and ''discriminating'' power of InSAR by presenting results from InSAR data processing, analysis and modeling of the surface deformation signals associated with underground explosions. Specifically, we present results of a detailed study of coseismic and postseismic surface deformation signals associated with underground nuclear and chemical explosion tests at the Nevada Test Site (NTS). Several interferograms were formed from raw ERS-1/2 radar data covering different time spans and epochs beginning just prior to the last U.S. nuclear tests in 1992 and ending in 1996. These interferograms have yielded information about the nature and duration of the source processes that produced the surface deformations associated with these events. A critical result of this study is that significant post-event surface deformation associated with underground nuclear explosions detonated at depths in excess of 600 meters can be detected using differential radar interferometry. An

Pion interferometric tests of transport models

Energy Technology Data Exchange (ETDEWEB)

Padula, S.S.; Gyulassy, M.; Gavin, S. (Lawrence Berkeley Lab., CA (USA). Nuclear Science Div.)

1990-01-08

In hadronic reactions, the usual space-time interpretation of pion interferometry often breaks down due to strong correlations between spatial and momentum coordinates. We derive a general interferometry formula based on the Wigner density formalism that allows for arbitrary phase space and multiparticle correlations. Correction terms due to intermediate state pion cascading are derived using semiclassical hadronic transport theory. Finite wave packets are used to reveal the sensitivity of pion interference effects on the details of the production dynamics. The covariant generalization of the formula is shown to be equivalent to the formula derived via an alternate current ensemble formalism for minimal wave packets and reduces in the nonrelativistic limit to a formula derived by Pratt. The final expression is ideally suited for pion interferometric tests of Monte Carlo transport models. Examples involving gaussian and inside-outside phase space distributions are considered. (orig.).

Pion interferometric tests of transport models

International Nuclear Information System (INIS)

Padula, S.S.; Gyulassy, M.; Gavin, S.

1990-01-01

In hadronic reactions, the usual space-time interpretation of pion interferometry often breaks down due to strong correlations between spatial and momentum coordinates. We derive a general interferometry formula based on the Wigner density formalism that allows for arbitrary phase space and multiparticle correlations. Correction terms due to intermediate state pion cascading are derived using semiclassical hadronic transport theory. Finite wave packets are used to reveal the sensitivity of pion interference effects on the details of the production dynamics. The covariant generalization of the formula is shown to be equivalent to the formula derived via an alternate current ensemble formalism for minimal wave packets and reduces in the nonrelativistic limit to a formula derived by Pratt. The final expression is ideally suited for pion interferometric tests of Monte Carlo transport models. Examples involving gaussian and inside-outside phase space distributions are considered. (orig.)

Reduction of interferometric crosstalk induced penalty using a saturated semiconductor optical amplifier

DEFF Research Database (Denmark)

Liu, Fenghai; Zheng, Xueyan; Poulsen, Henrik Nørskov

2000-01-01

We successfully demonstrated that a simple saturated SOA could be used to reduce the impact from the interferometric crosstalk at 2.5 and 10 Gb/s. It is shown that 4 dB more crosstalk power can be tolerated at 1 dB penalty by using the SOA. This will greatly reduce the crosstalk requirement...

A new interferometric study of four exoplanet host stars: θ Cygni, 14 Andromedae, υ Andromedae and 42 Draconis

Science.gov (United States)

Ligi, R.; Mourard, D.; Lagrange, A. M.; Perraut, K.; Boyajian, T.; Bério, Ph.; Nardetto, N.; Tallon-Bosc, I.; McAlister, H.; ten Brummelaar, T.; Ridgway, S.; Sturmann, J.; Sturmann, L.; Turner, N.; Farrington, C.; Goldfinger, P. J.

2012-09-01

Context. Since the discovery of the first exoplanet in 1995 around a solar-type star, the interest in exoplanetary systems has kept increasing. Studying exoplanet host stars is of the utmost importance to establish the link between the presence of exoplanets around various types of stars and to understand the respective evolution of stars and exoplanets. Aims: Using the limb-darkened diameter (LDD) obtained from interferometric data, we determine the fundamental parameters of four exoplanet host stars. We are particularly interested in the F4 main-sequence star, θ Cyg, for which Kepler has recently revealed solar-like oscillations that are unexpected for this type of star. Furthermore, recent photometric and spectroscopic measurements with SOPHIE and ELODIE (OHP) show evidence of a quasi-periodic radial velocity of ~150 days. Models of this periodic change in radial velocity predict either a complex planetary system orbiting the star, or a new and unidentified stellar pulsation mode. Methods: We performed interferometric observations of θ Cyg, 14 Andromedae, υ Andromedae and 42 Draconis for two years with VEGA/CHARA (Mount Wilson, California) in several three-telescope configurations. We measured accurate limb darkened diameters and derived their radius, mass and temperature using empirical laws. Results: We obtain new accurate fundamental parameters for stars 14 And, υ And and 42 Dra. We also obtained limb darkened diameters with a minimum precision of ~1.3%, leading to minimum planet masses of Msini = 5.33 ± 0.57, 0.62 ± 0.09 and 3.79 ± 0.29 MJup for 14 And b, υ And b and 42 Dra b, respectively. The interferometric measurements of θ Cyg show a significant diameter variability that remains unexplained up to now. We propose that the presence of these discrepancies in the interferometric data is caused either by an intrinsic variation of the star or an unknown close companion orbiting around it. Based on interferometric observations with the VEGA

Interferometric microstructured polymer optical fiber ultrasound sensor for optoacoustic endoscopic imaging in biomedical applications

DEFF Research Database (Denmark)

Gallego, Daniel; Sáez-Rodríguez, David; Webb, David

2014-01-01

to conventional piezoelectric transducers. These kind of sensors, made of biocompatible polymers, are good candidates for the sensing element in an optoacoustic endoscope because of its high sensitivity, its shape and its non-brittle and non-electric nature. The acoustic sensitivity of the intrinsic fiber optic......We report a characterization of the acoustic sensitivity of microstructured polymer optical fiber interferometric sensors at ultrasonic frequencies from 100kHz to 10MHz. The use of wide-band ultrasonic fiber optic sensors in biomedical ultrasonic and optoacoustic applications is an open alternative...... interferometric sensors depends strongly of the material which is composed of. In this work we compare experimentally the intrinsic ultrasonic sensitivities of a PMMA mPOF with other three optical fibers: a singlemode silica optical fiber, a single-mode polymer optical fiber and a multimode graded...

Mitigation of defocusing by statics and near-surface velocity errors by interferometric least-squares migration

KAUST Repository

Sinha, Mrinal; Schuster, Gerard T.

2015-01-01

the, e.g., well logs. Reflections from this reference layer are correlated with the traces associated with reflections from deeper interfaces to get crosscorrelograms. These crosscorrelograms are then migrated using interferometric least

Broadband infrared beam splitter for spaceborne interferometric infrared sounder.

Science.gov (United States)

Yu, Tianyan; Liu, Dingquan; Qin, Yang

2014-10-01

A broadband infrared beam splitter (BS) on ZnSe substrate used for the spaceborne interferometric infrared sounder (SIIRS) is studied in the spectral range of 4.44-15 μm. Both broadband antireflection coating and broadband beam-splitter coating in this BS are designed and tested. To optimize the optical properties and the stability of the BS, suitable infrared materials were selected, and improved deposition techniques were applied. The designed structures matched experimental data well, and the properties of the BS met the application specification of SIIRS.

Improving waveform inversion using modified interferometric imaging condition

Science.gov (United States)

Guo, Xuebao; Liu, Hong; Shi, Ying; Wang, Weihong; Zhang, Zhen

2018-02-01

Similar to the reverse-time migration, full waveform inversion in the time domain is a memory-intensive processing method. The computational storage size for waveform inversion mainly depends on the model size and time recording length. In general, 3D and 4D data volumes need to be saved for 2D and 3D waveform inversion gradient calculations, respectively. Even the boundary region wavefield-saving strategy creates a huge storage demand. Using the last two slices of the wavefield to reconstruct wavefields at other moments through the random boundary, avoids the need to store a large number of wavefields; however, traditional random boundary method is less effective at low frequencies. In this study, we follow a new random boundary designed to regenerate random velocity anomalies in the boundary region for each shot of each iteration. The results obtained using the random boundary condition in less illuminated areas are more seriously affected by random scattering than other areas due to the lack of coverage. In this paper, we have replaced direct correlation for computing the waveform inversion gradient by modified interferometric imaging, which enhances the continuity of the imaging path and reduces noise interference. The new imaging condition is a weighted average of extended imaging gathers can be directly used in the gradient computation. In this process, we have not changed the objective function, and the role of the imaging condition is similar to regularization. The window size for the modified interferometric imaging condition-based waveform inversion plays an important role in this process. The numerical examples show that the proposed method significantly enhances waveform inversion performance.

Dynamic spectro-polarimeter based on a modified Michelson interferometric scheme.

Science.gov (United States)

Dembele, Vamara; Jin, Moonseob; Baek, Byung-Joon; Kim, Daesuk

2016-06-27

A simple dynamic spectro-polarimeter based on a modified Michelson interferometric scheme is described. The proposed system can extract a spectral Stokes vector of a transmissive anisotropic object. Detail theoretical background is derived and experiments are conducted to verify the feasibility of the proposed novel snapshot spectro-polarimeter. The proposed dynamic spectro-polarimeter enables us to extract highly accurate spectral Stokes vector of any transmissive anisotropic object with a frame rate of more than 20Hz.

Evidence of a metal-rich surface for the Asteroid (16) Psyche from interferometric observations in the thermal infrared

Science.gov (United States)

Matter, Alexis; Delbo, Marco; Carry, Benoit; Ligori, Sebastiano

2013-09-01

We describe the first determination of thermal properties and size of the M-type Asteroid (16) Psyche from interferometric observations obtained with the Mid-Infrared Interferometric Instrument (MIDI) of the Very Large Telescope Interferometer. We used a thermophysical model to interpret our interferometric data. Our analysis shows that Psyche has a low macroscopic surface roughness. Using a convex 3-D shape model obtained by Kaasalainen et al. (Kaasalainen, M., Torppa, J., Piironen, J. [2002]. Icarus 159, 369-395), we derived a volume-equivalent diameter for (16) Psyche of 247 ± 25 km or 238 ± 24 km, depending on the possible values of surface roughness. Our corresponding thermal inertia estimates are 133 or 114 J m-2 s-0.5 K-1, with a total uncertainty estimated at 40 J m-2 s-0.5 K-1. They are among the highest thermal inertia values ever measured for an asteroid of this size. We consider this as a new evidence of a metal-rich surface for the Asteroid (16) Psyche.

Landslide Susceptibility Mapping Using GIS-based Vector Grid File (VGF Validating with InSAR Techniques: Three Gorges, Yangtze River (China

Directory of Open Access Journals (Sweden)

Cem Kıncal

2017-04-01

Full Text Available A landslide susceptibility assessment for the Three Gorges (TG region (China was performed in a Geographical Information System (GIS environment and Persistent Scatterer (PS InSAR derived displacements were used for validation purposes. Badong County of TG was chosen as case study field. Landslide parameters were derived from two datasets. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER Global Digital Elevation Map (GDEM was used to calculate slope geometry parameters (slope, aspect, drainage, and lineament, while geology and vegetation cover were obtained from Landsat and ASTER data. The majority of historical landslides occurred in the sandstone-shale-claystone intercalations. It appears that slope gradients are more critical than other parameters such as aspect and drainage. The susceptibility assessment was based on a summation of assigned susceptibility scores (points for each 30×30 m unit in a database of a Vector Grid File (VGF composed of ‘vector pixels’. A landslide susceptibility map (LSM was generated using VGF and classified with low, moderate and high landslide susceptibility zones. The comparison between the LSM and PS InSAR derived displacements suggests that landslides only account for parts of the observed surface movements.

Distortion compensation in interferometric testing of mirrors

International Nuclear Information System (INIS)

Robinson, Brian M.; Reardon, Patrick J.

2009-01-01

We present a method to compensate for the imaging distortion encountered in interferometric testing of mirrors, which is introduced by interferometer optics as well as from geometric projection errors. Our method involves placing a mask, imprinted with a regular square grid, over the mirror and finding a transformation that relates the grid coordinates to coordinates in the base plane of the parent surface. This method can be used on finished mirrors since no fiducials have to be applied to the surfaces. A critical step in the process requires that the grid coordinates be projected onto the mirror base plane before the regression is performed. We apply the method successfully during a center-of-curvature null test of an F/2 off-axis paraboloid

Interferometric full-waveform inversion of time-lapse data

KAUST Repository

Sinha, Mrinal

2017-08-17

One of the key challenges associated with time-lapse surveys is ensuring the repeatability between the baseline and monitor surveys. Non-repeatability between the surveys is caused by varying environmental conditions over the course of different surveys. To overcome this challenge, we propose the use of interferometric full waveform inversion (IFWI) for inverting the velocity model from data recorded by baseline and monitor surveys. A known reflector is used as the reference reflector for IFWI, and the data are naturally redatumed to this reference reflector using natural reflections as the redatuming operator. This natural redatuming mitigates the artifacts introduced by the repeatability errors that originate above the reference reflector.

Building Deformation Assessment by Means of Persistent Scatterer Interferometry Analysis on a Landslide-Affected Area: The Volterra (Italy Case Study

Directory of Open Access Journals (Sweden)

Silvia Bianchini

2015-04-01

Full Text Available In recent years, space-borne InSAR (interferometric synthetic aperture radar techniques have shown their capabilities to provide precise measurements of Earth surface displacements for monitoring natural processes. Landslides threaten human lives and structures, especially in urbanized areas, where the density of elements at risk sensitive to ground movements is high. The methodology described in this paper aims at detecting terrain motions and building deformations at the local scale, by means of satellite radar data combined with in situ validation campaigns. The proposed approach consists of deriving maximum settlement directions of the investigated buildings from displacement data revealed by radar measurements and then in the cross-comparison of these values with background geological data, constructive features and on-field evidence. This validation permits better understanding whether or not the detected movements correspond to visible and effective damages to buildings. The method has been applied to the southwestern sector of Volterra (Tuscany region, Italy, which is a landslide-affected and partially urbanized area, through the use of COSMO-SkyMed satellite images as input data. Moreover, we discuss issues and possible misinterpretations when dealing with PSI (Persistent Scatterer Interferometry data referring to single manufactures and the consequent difficulty of attributing the motion rate to ground displacements, rather than to structural failures.

From coseismic offsets to fault-block mountains

Science.gov (United States)

Thompson, George A.; Parsons, Tom

2017-09-01

In the Basin and Range extensional province of the western United States, coseismic offsets, under the influence of gravity, display predominantly subsidence of the basin side (fault hanging wall), with comparatively little or no uplift of the mountainside (fault footwall). A few decades later, geodetic measurements [GPS and interferometric synthetic aperture radar (InSAR)] show broad (˜100 km) aseismic uplift symmetrically spanning the fault zone. Finally, after millions of years and hundreds of fault offsets, the mountain blocks display large uplift and tilting over a breadth of only about 10 km. These sparse but robust observations pose a problem in that the coesismic uplifts of the footwall are small and inadequate to raise the mountain blocks. To address this paradox we develop finite-element models subjected to extensional and gravitational forces to study time-varying deformation associated with normal faulting. Stretching the model under gravity demonstrates that asymmetric slip via collapse of the hanging wall is a natural consequence of coseismic deformation. Focused flow in the upper mantle imposed by deformation of the lower crust localizes uplift, which is predicted to take place within one to two decades after each large earthquake. Thus, the best-preserved topographic signature of earthquakes is expected to occur early in the postseismic period.

Mission Analysis and Orbit Control of Interferometric Wheel Formation Flying

Science.gov (United States)

Fourcade, J.

Flying satellite in formation requires maintaining the specific relative geometry of the spacecraft with high precision. This requirement raises new problem of orbit control. This paper presents the results of the mission analysis of a low Earth observation system, the interferometric wheel, patented by CNES. This wheel is made up of three receiving spacecraft, which follow an emitting Earth observation radar satellite. The first part of this paper presents trades off which were performed to choose orbital elements of the formation flying which fulfils all constraints. The second part presents orbit positioning strategies including reconfiguration of the wheel to change its size. The last part describes the station keeping of the formation. Two kinds of constraints are imposed by the interferometric system : a constraint on the distance between the wheel and the radar satellite, and constraints on the distance between the wheel satellites. The first constraint is fulfilled with a classical chemical station keeping strategy. The second one is fulfilled using pure passive actuators. Due to the high stability of the relative eccentricity of the formation, only the relative semi major axis had to be controlled. Differential drag due to differential attitude motion was used to control relative altitude. An autonomous orbit controller was developed and tested. The final accuracy is a relative station keeping better than few meters for a wheel size of one kilometer.

Natural - synthetic - artificial!

DEFF Research Database (Denmark)

Nielsen, Peter E

2010-01-01

The terms "natural," "synthetic" and "artificial" are discussed in relation to synthetic and artificial chromosomes and genomes, synthetic and artificial cells and artificial life.......The terms "natural," "synthetic" and "artificial" are discussed in relation to synthetic and artificial chromosomes and genomes, synthetic and artificial cells and artificial life....

Efficient inversion of volcano deformation based on finite element models : An application to Kilauea volcano, Hawaii

Science.gov (United States)

Charco, María; González, Pablo J.; Galán del Sastre, Pedro

2017-04-01

The Kilauea volcano (Hawaii, USA) is one of the most active volcanoes world-wide and therefore one of the better monitored volcanoes around the world. Its complex system provides a unique opportunity to investigate the dynamics of magma transport and supply. Geodetic techniques, as Interferometric Synthetic Aperture Radar (InSAR) are being extensively used to monitor ground deformation at volcanic areas. The quantitative interpretation of such surface ground deformation measurements using geodetic data requires both, physical modelling to simulate the observed signals and inversion approaches to estimate the magmatic source parameters. Here, we use synthetic aperture radar data from Sentinel-1 radar interferometry satellite mission to image volcano deformation sources during the inflation along Kilauea's Southwest Rift Zone in April-May 2015. We propose a Finite Element Model (FEM) for the calculation of Green functions in a mechanically heterogeneous domain. The key aspect of the methodology lies in applying the reciprocity relationship of the Green functions between the station and the source for efficient numerical inversions. The search for the best-fitting magmatic (point) source(s) is generally conducted for an array of 3-D locations extending below a predefined volume region. However, our approach allows to reduce the total number of Green functions to the number of the observation points by using the, above mentioned, reciprocity relationship. This new methodology is able to accurately represent magmatic processes using physical models capable of simulating volcano deformation in non-uniform material properties distribution domains, which eventually will lead to better description of the status of the volcano.

Subsidence Evaluation of High-Speed Railway in Shenyang Based on Time-Series Insar

Science.gov (United States)

Zhang, Yun; Wei, Lianhuan; Li, Jiayu; Liu, Shanjun; Mao, Yachun; Wu, Lixin

2018-04-01

More and more high-speed railway are under construction in China. The slow settlement along high-speed railway tracks and newly-built stations would lead to inhomogeneous deformation of local area, and the accumulation may be a threat to the safe operation of high-speed rail system. In this paper, surface deformation of the newly-built high-speed railway station as well as the railway lines in Shenyang region will be retrieved by time series InSAR analysis using multi-orbit COSMO-SkyMed images. This paper focuses on the non-uniform subsidence caused by the changing of local environment along the railway. The accuracy of the settlement results can be verified by cross validation of the results obtained from two different orbits during the same period.

The Space Infrared Interferometric Telescope (SPIRIT)

Science.gov (United States)

Leisawitz, David T.

2014-01-01

The far-infrared astrophysics community is eager to follow up Spitzer and Herschel observations with sensitive, high-resolution imaging and spectroscopy, for such measurements are needed to understand merger-driven star formation and chemical enrichment in galaxies, star and planetary system formation, and the development and prevalence of water-bearing planets. The Space Infrared Interferometric Telescope (SPIRIT) is a wide field-of-view space-based spatio-spectral interferometer designed to operate in the 25 to 400 micron wavelength range. This talk will summarize the SPIRIT mission concept, with a focus on the science that motivates it and the technology that enables it. Without mentioning SPIRIT by name, the astrophysics community through the NASA Astrophysics Roadmap Committee recently recommended this mission as the first in a series of space-based interferometers. Data from a laboratory testbed interferometer will be used to illustrate how the spatio-spectral interferometry technique works.

On the COSMO-SkyMed Exploitation for Interferometric DEM Generation

Science.gov (United States)

Teresa, C. M.; Raffaele, N.; Oscar, N. D.; Fabio, B.

2011-12-01

DEM products for Earth observation space-borne applications are being to play a role of increasing importance due to the new generation of high resolution sensors (both optical and SAR). These new sensors demand elevation data for processing and, on the other hand, they provide new possibilities for DEM generation. Till now, for what concerns interferometric DEM, the Shuttle Radar Topography Mission (SRTM) has been the reference product for scientific applications all over the world. SRTM mission [1] had the challenging goal to meet the requirements for a homogeneous and reliable DEM fulfilling the DTED-2 specifications. However, new generation of high resolution sensors (including SAR) pose new requirements for elevation data in terms of vertical precision and spatial resolution. DEM are usually used as ancillary input in different processing steps as for instance geocoding and Differential SAR Interferometry. In this context, the recent SAR missions of DLR (TerraSAR-X and TanDEM-X) and ASI (COSMO-SkyMed) can play a promising role thanks to their high resolution both in space and time. In particular, the present work investigates the potentialities of the COSMO/SkyMed (CSK) constellation for ground elevation measurement with particular attention devoted to the impact of the improved spatial resolution wrt the previous SAR sensors. The recent scientific works, [2] and [3], have shown the advantages of using CSK in the monitoring of terrain deformations caused by landslides, earthquakes, etc. On the other hand, thanks to the high spatial resolution, CSK appears to be very promising in monitoring man-made structures, such as buildings, bridges, railways and highways, thus enabling new potential applications (urban applications, precise DEM, etc.). We present results obtained by processing both SPOTLIGHT and STRIPMAP acquisitions through standard SAR Interferometry as well as multi-pass interferometry [4] with the aim of measuring ground elevation. Acknowledgments

MEASUREMENT OF SEAWARD GROUND DISPLACEMENTS ON COASTAL LANDFILL AREA USING RADAR INTERFEROMETRY

Directory of Open Access Journals (Sweden)

W.-K. Baek

2018-04-01

Full Text Available In order to understand the mechanism of subsidence and help reducing damage, researchers has been observed the line-of-sight subsidence on the Noksan industrial complex using SAR Interferometry(InSAR and suggested subsidence prediction models. Although these researches explained a spatially uneven ground subsidence near the seaside, they could not have been explained the occurrence of the newly proposed seaward horizontal, especially nearly north-ward, displacement because of the geometric limitation of InSAR measurements. In this study, we measured the seaward ground displacements trend on the coastal landfill area, Noksan Industrial Complex. We set the interferometric pairs from an ascending and a descending orbits strip map data of ALOS PALSAR2. We employed InSAR and MAI stacking approaches for the both orbits respectively in order to improve the measurement. Finally, seaward deformation was estimated by retrieving three-dimensional displacements from multi-geometric displacements. As a results, maximally 3.3 and 0.7 cm/year of ground displacements for the vertical and seaward directions. In further study, we plan to generate InSAR and MAI stacking measurements with additional SAR data to mitigate tropospheric effect and noise well. Such a seaward observation approach using spaceborne radar is expected to be effective in observing the long-term movements on coastal landfill area.

Data quality studies of enhanced interferometric gravitational wave detectors

International Nuclear Information System (INIS)

McIver, Jessica

2012-01-01

Data quality assessment plays an essential role in the quest to detect gravitational wave signals in data from the LIGO and Virgo interferometric gravitational wave detectors. Interferometer data contain a high rate of noise transients from the environment, the detector hardware and the detector control systems. These transients severely limit the statistical significance of gravitational wave candidates of short duration and/or poorly modeled waveforms. This paper describes the data quality studies that have been performed in recent LIGO and Virgo observing runs to mitigate the impact of transient detector artifacts on the gravitational wave searches. (paper)

Reconstruction of source location in a network of gravitational wave interferometric detectors

International Nuclear Information System (INIS)

Cavalier, Fabien; Barsuglia, Matteo; Bizouard, Marie-Anne; Brisson, Violette; Clapson, Andre-Claude; Davier, Michel; Hello, Patrice; Kreckelbergh, Stephane; Leroy, Nicolas; Varvella, Monica

2006-01-01

This paper deals with the reconstruction of the direction of a gravitational wave source using the detection made by a network of interferometric detectors, mainly the LIGO and Virgo detectors. We suppose that an event has been seen in coincidence using a filter applied on the three detector data streams. Using the arrival time (and its associated error) of the gravitational signal in each detector, the direction of the source in the sky is computed using a χ 2 minimization technique. For reasonably large signals (SNR>4.5 in all detectors), the mean angular error between the real location and the reconstructed one is about 1 deg. . We also investigate the effect of the network geometry assuming the same angular response for all interferometric detectors. It appears that the reconstruction quality is not uniform over the sky and is degraded when the source approaches the plane defined by the three detectors. Adding at least one other detector to the LIGO-Virgo network reduces the blind regions and in the case of 6 detectors, a precision less than 1 deg. on the source direction can be reached for 99% of the sky

Seven years of postseismic deformation following the 2003 Mw = 6.8 Zemmouri earthquake (Algeria) from InSAR time series

KAUST Repository

Cetin, Esra

2012-05-28

We study the postseismic surface deformation of the Mw 6.8, 2003 Zemmouri earthquake (northern Algeria) using the Multi-Temporal Small Baseline InSAR technique. InSAR time series obtained from 31 Envisat ASAR images from 2003 to 2010 reveal sub-cm coastline ground movements between Cap Matifou and Dellys. Two regions display subsidence at a maximum rate of 2 mm/yr in Cap Djenet and 3.5 mm/yr in Boumerdes. These regions correlate well with areas of maximum coseismic uplifts, and their association with two rupture segments. Inverse modeling suggest that subsidence in the areas of high coseismic uplift can be explained by afterslip on shallow sections (<5 km) of the fault above the areas of coseismic slip, in agreement with previous GPS observations. The earthquake impact on soft sediments and the ground water table southwest of the earthquake area, characterizes ground deformation of non-tectonic origin. The cumulative postseismic moment due to 7 years afterslip is equivalent to an Mw 6.3 earthquake. Therefore, the postseismic deformation and stress buildup has significant implications on the earthquake cycle models and recurrence intervals of large earthquakes in the Algiers area.

Seven years of postseismic deformation following the 2003 Mw = 6.8 Zemmouri earthquake (Algeria) from InSAR time series

KAUST Repository

Cetin, Esra; Meghraoui, Mustapha; Cakir, Ziyadin; Akoglu, Ahmet M.; Mimouni, Omar; Chebbah, Mouloud

2012-01-01

We study the postseismic surface deformation of the Mw 6.8, 2003 Zemmouri earthquake (northern Algeria) using the Multi-Temporal Small Baseline InSAR technique. InSAR time series obtained from 31 Envisat ASAR images from 2003 to 2010 reveal sub-cm coastline ground movements between Cap Matifou and Dellys. Two regions display subsidence at a maximum rate of 2 mm/yr in Cap Djenet and 3.5 mm/yr in Boumerdes. These regions correlate well with areas of maximum coseismic uplifts, and their association with two rupture segments. Inverse modeling suggest that subsidence in the areas of high coseismic uplift can be explained by afterslip on shallow sections (<5 km) of the fault above the areas of coseismic slip, in agreement with previous GPS observations. The earthquake impact on soft sediments and the ground water table southwest of the earthquake area, characterizes ground deformation of non-tectonic origin. The cumulative postseismic moment due to 7 years afterslip is equivalent to an Mw 6.3 earthquake. Therefore, the postseismic deformation and stress buildup has significant implications on the earthquake cycle models and recurrence intervals of large earthquakes in the Algiers area.

Optimization of silicon oxynitrides by plasma-enhanced chemical vapor deposition for an interferometric biosensor

Science.gov (United States)

Choo, Sung Joong; Lee, Byung-Chul; Lee, Sang-Myung; Park, Jung Ho; Shin, Hyun-Joon

2009-09-01

In this paper, silicon oxynitride layers deposited with different plasma-enhanced chemical vapor deposition (PECVD) conditions were fabricated and optimized, in order to make an interferometric sensor for detecting biochemical reactions. For the optimization of PECVD silicon oxynitride layers, the influence of the N2O/SiH4 gas flow ratio was investigated. RF power in the PEVCD process was also adjusted under the optimized N2O/SiH4 gas flow ratio. The optimized silicon oxynitride layer was deposited with 15 W in chamber under 25/150 sccm of N2O/SiH4 gas flow rates. The clad layer was deposited with 20 W in chamber under 400/150 sccm of N2O/SiH4 gas flow condition. An integrated Mach-Zehnder interferometric biosensor based on optical waveguide technology was fabricated under the optimized PECVD conditions. The adsorption reaction between bovine serum albumin (BSA) and the silicon oxynitride surface was performed and verified with this device.

Fusion of Multi-Temporal Interferometric Coherence and Optical Image Data for the 2016 Kumamoto Earthquake Damage Assessment

Directory of Open Access Journals (Sweden)

Nopphawan Tamkuan

2017-06-01

Full Text Available Earthquakes are one of the most devastating types of natural disasters, and happen with little to no warning. This study combined Landsat-8 and interferometric ALOS-2 coherence data without training area techniques by classifying the remote sensing ratios of specific features for damage assessment. Waterbodies and highly vegetated areas were extracted by the modified normalized difference water index (MNDWI and normalized difference vegetation index (NDVI, respectively, from after-earthquake images in order to improve the accuracy of damage maps. Urban areas were classified from pre-event interferometric coherence data. The affected areas from the earthquake were detected with the normalized difference (ND between the pre- and co-event interferometric coherence. The results presented three damage types; namely, damage to buildings caused by ground motion, liquefaction, and landslides. The overall accuracy (94% of the confusion matrix was excellent. Results for urban areas were divided into three damage levels (e.g., none–slight, slight–heavy, heavy–destructive at a high (90% overall accuracy level. Moreover, data on buildings damaged by liquefaction and landslides were in good agreement with field survey information. Overall, this study illustrates an effective damage assessment mapping approach that can support post-earthquake management activities for future events, especially in areas where geographical data are sparse.

Interseismic Coupling on the Quito Fault System in Ecuador Using New GPS and InSAR Data and Its Implication on Seismic Hazard Assessment.

Science.gov (United States)

Mariniere, J.; Champenois, J.; Nocquet, J. M.; Beauval, C. M.; Audin, L.; Baize, S.; Alvarado, A. P.; Yepes, H. A.; Jomard, H.

2017-12-01

Quito, the capital of Ecuador hosting two million inhabitants lies on an active reverse fault system within the Andes. Regular moderate size earthquakes (M 5) occur on these faults, widely felt within the city and its surrounding. Despite a relatively small magnitude of Mw 5.1, the 2014 August 12 earthquake triggered landslides that killed 4 people, cut off one of the main highways for several weeks and caused the temporary shutdown of the airport. Quantifying the seismic potential of the Quito fault system is therefore crucial for a better preparation and mitigation to seismic risk. Previous work using a limited GPS data set found that the Quito fault accommodates 4 mm/yr of EW shortening (Alvarado et al., 2014) at shallow locking depths (3-7 km). We combine GPS and new InSAR data to extend the previous analysis and better quantify the spatial distribution of locking of the Quito fault. GPS dataset includes new continuous sites operating since 2013. 18 ERS SAR scenes, spanning the 1993-2000 time period and covering an area of 85 km by 30 km, were processed using a Permanent Scatter strategy. We perform a joint inversion of both data set (GPS and InSAR) to infer a new and better-constrained kinematic model of the fault to determine both the slip rate and the locking distribution at depth. We find a highly variable level of locking which changes along strike. At some segments, sharp displacement gradients observed both for GPS and InSAR suggest that the fault is creeping up to the surface, while shallow locking is found for other segments. Previous Probabilistic Seismic Hazard Assessment studies have shown that the Quito fault fully controls the hazard in Quito city (Beauval et al. 2014). The results will be used to improve the forecast of earthquakes on the Quito fault system for PSHA studies.

Fundamentals of interferometric gravitational wave detectors

CERN Document Server

Saulson, Peter R

2017-01-01

LIGO's recent discovery of gravitational waves was headline news around the world. Many people will want to understand more about what a gravitational wave is, how LIGO works, and how LIGO functions as a detector of gravitational waves.This book aims to communicate the basic logic of interferometric gravitational wave detectors to students who are new to the field. It assumes that the reader has a basic knowledge of physics, but no special familiarity with gravitational waves, with general relativity, or with the special techniques of experimental physics. All of the necessary ideas are developed in the book.The first edition was published in 1994. Since the book is aimed at explaining the physical ideas behind the design of LIGO, it stands the test of time. For the second edition, an Epilogue has been added; it brings the treatment of technical details up to date, and provides references that would allow a student to become proficient with today's designs.

LSPR and Interferometric Sensor Modalities Combined Using a Double-Clad Optical Fiber.

Science.gov (United States)

Muri, Harald Ian; Bano, Andon; Hjelme, Dag Roar

2018-01-11

We report on characterization of an optical fiber-based multi-parameter sensor concept combining localized surface plasmon resonance (LSPR) signal and interferometric sensing using a double-clad optical fiber. The sensor consists of a micro-Fabry-Perot in the form of a hemispherical stimuli-responsive hydrogel with immobilized gold nanorods on the facet of a cleaved double-clad optical fiber. The swelling degree of the hydrogel is measured interferometrically using the single-mode inner core, while the LSPR signal is measured using the multi-mode inner cladding. The quality of the interferometric signal is comparable to previous work on hydrogel micro-Fabry-Perot sensors despite having gold nanorods immobilized in the hydrogel. We characterize the effect of hydrogel swelling and variation of bulk solution refractive index on the LSPR peak wavelength. The results show that pH-induced hydrogel swelling causes only weak redshifts of the longitudinal LSPR mode, while increased bulk refractive index using glycerol and sucrose causes large blueshifts. The redshifts are likely due to reduced plasmon coupling of the side-by-side configuration as the interparticle distance increases with increasing swelling. The blueshifts with increasing bulk refractive index are likely due to alteration of the surface electronic structure of the gold nanorods donated by the anionic polymer network and glycerol or sucrose solutions. The recombination of biotin-streptavidin on gold nanorods in hydrogel showed a 7.6 nm redshift of the longitudinal LSPR. The LSPR response of biotin-streptavidin recombination is due to the change in local refractive index (RI), which is possible to discriminate from the LSPR response due to changes in bulk RI. In spite of the large LSPR shifts due to bulk refractive index, we show, using biotin-functionalized gold nanorods binding to streptavidin, that LSPR signal from gold nanorods embedded in the anionic hydrogel can be used for label-free biosensing. These

LSPR and Interferometric Sensor Modalities Combined Using a Double-Clad Optical Fiber

Directory of Open Access Journals (Sweden)

Harald Ian Muri

2018-01-01

Full Text Available We report on characterization of an optical fiber-based multi-parameter sensor concept combining localized surface plasmon resonance (LSPR signal and interferometric sensing using a double-clad optical fiber. The sensor consists of a micro-Fabry-Perot in the form of a hemispherical stimuli-responsive hydrogel with immobilized gold nanorods on the facet of a cleaved double-clad optical fiber. The swelling degree of the hydrogel is measured interferometrically using the single-mode inner core, while the LSPR signal is measured using the multi-mode inner cladding. The quality of the interferometric signal is comparable to previous work on hydrogel micro-Fabry-Perot sensors despite having gold nanorods immobilized in the hydrogel. We characterize the effect of hydrogel swelling and variation of bulk solution refractive index on the LSPR peak wavelength. The results show that pH-induced hydrogel swelling causes only weak redshifts of the longitudinal LSPR mode, while increased bulk refractive index using glycerol and sucrose causes large blueshifts. The redshifts are likely due to reduced plasmon coupling of the side-by-side configuration as the interparticle distance increases with increasing swelling. The blueshifts with increasing bulk refractive index are likely due to alteration of the surface electronic structure of the gold nanorods donated by the anionic polymer network and glycerol or sucrose solutions. The recombination of biotin-streptavidin on gold nanorods in hydrogel showed a 7.6 nm redshift of the longitudinal LSPR. The LSPR response of biotin-streptavidin recombination is due to the change in local refractive index (RI, which is possible to discriminate from the LSPR response due to changes in bulk RI. In spite of the large LSPR shifts due to bulk refractive index, we show, using biotin-functionalized gold nanorods binding to streptavidin, that LSPR signal from gold nanorods embedded in the anionic hydrogel can be used for label

Plant synthetic biology.

Science.gov (United States)

Liu, Wusheng; Stewart, C Neal

2015-05-01

Plant synthetic biology is an emerging field that combines engineering principles with plant biology toward the design and production of new devices. This emerging field should play an important role in future agriculture for traditional crop improvement, but also in enabling novel bioproduction in plants. In this review we discuss the design cycles of synthetic biology as well as key engineering principles, genetic parts, and computational tools that can be utilized in plant synthetic biology. Some pioneering examples are offered as a demonstration of how synthetic biology can be used to modify plants for specific purposes. These include synthetic sensors, synthetic metabolic pathways, and synthetic genomes. We also speculate about the future of synthetic biology of plants. Copyright © 2015 Elsevier Ltd. All rights reserved.

Volcano-tectonic interactions at Sabancaya and other Peruvian volcanoes revealed by InSAR and seismicity

Science.gov (United States)

Jay, J.; Pritchard, M. E.; Aron, F.; Delgado, F.; Macedo, O.; Aguilar, V.

2013-12-01

An InSAR survey of all 13 Holocene volcanoes in the Andean Central Volcanic Zone of Peru reveals previously undocumented surface deformation that is occasionally accompanied by seismic activity. Our survey utilizes SAR data spanning from 1992 to the present from the ERS-1, ERS-2, and Envisat satellites, as well as selected data from the TerraSAR-X satellite. We find that the recent unrest at Sabancaya volcano (heightened seismicity since 22 February 2013 and increased fumarolic output) has been accompanied by surface deformation. We also find two distinct deformation episodes near Sabancaya that are likely associated with an earthquake swarm in February 2013 and a M6 normal fault earthquake that occurred on 17 July 2013. Preliminary modeling suggests that faulting from the observed seismic moment can account for nearly all of the observed deformation and thus we have not yet found clear evidence for recent magma intrusion. We also document an earlier episode of deformation that occurred between December 2002 and September 2003 which may be associated with a M5.3 earthquake that occurred on 13 December 2002 on the Solarpampa fault, a large EW-striking normal fault located about 25 km northwest of Sabancaya volcano. All of the deformation episodes between 2002 and 2013 are spatially distinct from the inflation seen near Sabancaya from 1992 to 1997. In addition to the activity at Sabancaya, we also observe deformation near Coropuna volcano, in the Andagua Valley, and in the region between Ticsani and Tutupaca volcanoes. InSAR images reveal surface deformation that is possibly related to an earthquake swarm near Coropuna and Sabancaya volcanoes in December 2001. We also find persistent deformation in the scoria cone and lava field along the Andagua Valley, located 40 km east of Corpuna. An earthquake swarm near Ticsani volcano in 2005 produced surface deformation centered northwest of the volcano and was accompanied by a north-south elongated subsidence signal to the

Something is “subsiding” in the state of Denmark - Operational prospects for nationwide subsidence mapping with Sentinel-1

DEFF Research Database (Denmark)

Marinkovic, Petar; Larsen, Yngvar; Fredenslund Levinsen, Joanna

Synthetic Aperture Radar Interferometry (InSAR) has proven to be a highly valuable tool for deformation monitoring applications, and with the emergence of the operational Sentinel-1 mission, the expectations have further increased. However, the technique is also notorious for being challenging, b...

InSAR data analysis at Kamchatka during 2016

Directory of Open Access Journals (Sweden)

Larionov Igor

2017-01-01

Full Text Available Geophysical monitoring in seismically active areas depends on geodeformation processes in the earth's crust. Observations of earth's crust strain-stress using gps-measurements, laser interferometers give only an opportunity to analyze the dynamics in time without the possibility of extrapolation to adjacent areas. In this regard, it is useful to apply a radar interferometry technology to measure the displacements of the earth's surface. The report includes the results of processing the radar data of the Sentinel-1A satellite. Several qualitative interferometric pairs were obtained during the period from June to October 2016. A high coherence coefficient is observed in open areas in the vicinity of volcanic structures and adjacent territories, as well as on the west coast of Kamchatka, where there is no high vegetation. The main factor that significantly reduces the coherence of images is the forest cover. Possibility of estimating the surface displacement at regions with a high coherence coefficient is discussed.

Caldera deformation in Kyushu island (SW Japan) through InSAR data

Science.gov (United States)

Nobile, Adriano; Pepe, Susi; Ruch, Joel; Trippanera, Daniele; Casu, Francesco; Castaldo, Raffaele; Tizzani, Pietro; Aoki, Yosuke; Geshi, Nobuo; Acocella, Valerio; Sansosti, Eugenio; Siniscalchi, Valeria; Borgstrom, Sven; Zoffoli, Simona

2014-05-01

Calderas are the surface expression of a long-lived and complex magmatic system, often hosting a shallower hydrothermal system. Most monitored calderas have experienced some forms of unrest, even though only a part of these unrest episodes has culminated in an eruption. This study focuses on surface deformation analysis using InSAR from 1993 to 2013 at two large active calderas, Aso and Aira, located on Kyushu Island (Japan). Despite being closely monitored, our knowledge on the deformation history of both calderas with regard to their activity is poor. ERS, ENVISAT, ALOS and COSMO-SkyMed SAR images have been processed to obtain mean velocity deformation maps and time series through the SBAS technique. Results are then inverted using the simulated annealing technique to evaluate the deformation source parameters. Aso caldera hosts several vents in its central portion. One of these, the Naka Dake crater is the only currently active and erupted 7 times since 1993. From January 1996 to November 1998, after the important 1994 - 1995 eruption, we observed a subsidence of ~1.2 cm/yr at the center of the caldera. Analytical models suggest a deflating source (with various possible shapes) at 5-7 km of depth, implying a magmatic nature for the deformation. Inversion results are consistent with available seismic and GPS data. Aira Caldera hosts the Sakurajima volcano along its southern rim, with a persistent eruptive activity since 1950s. From June 2006 to March 2011, we observed a broad uplift of ~1.5 cm along most of the caldera rim. Analytical inversion of both the entire dataset and a cross-correlated dataset suggests a deformation source at the caldera center, at a depth of 5-9 km (depending on the source shape), implying a magmatic nature of the deformation. Inversion results are in agreement with GPS and InSAR data inversions for other periods of activity. This research has been partially performed within the frame of Italian Space Agency (ASI) and Japan Aerospace

The EDGE-CALIFA Survey: Interferometric Observations of 126 Galaxies with CARMA

Science.gov (United States)

Bolatto, Alberto D.; Wong, Tony; Utomo, Dyas; Blitz, Leo; Vogel, Stuart N.; Sánchez, Sebastián F.; Barrera-Ballesteros, Jorge; Cao, Yixian; Colombo, Dario; Dannerbauer, Helmut; García-Benito, Rubén; Herrera-Camus, Rodrigo; Husemann, Bernd; Kalinova, Veselina; Leroy, Adam K.; Leung, Gigi; Levy, Rebecca C.; Mast, Damián; Ostriker, Eve; Rosolowsky, Erik; Sandstrom, Karin M.; Teuben, Peter; van de Ven, Glenn; Walter, Fabian

2017-09-01

We present interferometric CO observations, made with the Combined Array for Millimeter-wave Astronomy (CARMA) interferometer, of galaxies from the Extragalactic Database for Galaxy Evolution survey (EDGE). These galaxies are selected from the Calar Alto Legacy Integral Field Area (CALIFA) sample, mapped with optical integral field spectroscopy. EDGE provides good-quality CO data (3σ sensitivity {{{Σ }}}{mol}˜ 11 {M}⊙ {{pc}}-2 before inclination correction, resolution ˜1.4 kpc) for 126 galaxies, constituting the largest interferometric CO survey of galaxies in the nearby universe. We describe the survey and data characteristics and products, then present initial science results. We find that the exponential scale lengths of the molecular, stellar, and star-forming disks are approximately equal, and galaxies that are more compact in molecular gas than in stars tend to show signs of interaction. We characterize the molecular-to-stellar ratio as a function of Hubble type and stellar mass and present preliminary results on the resolved relations between the molecular gas, stars, and star-formation rate. We then discuss the dependence of the resolved molecular depletion time on stellar surface density, nebular extinction, and gas metallicity. EDGE provides a key data set to address outstanding topics regarding gas and its role in star formation and galaxy evolution, which will be publicly available on completion of the quality assessment.

Synthetic Cannabinoids

Directory of Open Access Journals (Sweden)

Aslihan Okan Ibiloglu

2017-09-01

Full Text Available Synthetic cannabinoids which is a subgroup of cannabinoids are commonly used for recreational drug use throughout the whole world. Although both marijuana and synthetic cannabinoids stimulate the same receptors, cannabinoid receptor 1 (CB1 and cannabinoid receptor 2 (CB2, studies have shown that synthetic cannabinoids are much more potent than marijuana. The longer use of synthetic cannabinoids can cause severe physical and psychological symptoms that might even result in death, similar to many known illicit drugs. Main treatment options mostly involve symptom management and supportive care. The aim of this article is to discuss clinical and pharmacological properties of the increasingly used synthetic cannabinoids. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2017; 9(3.000: 317-328

Low-redundancy linear arrays in mirrored interferometric aperture synthesis.

Science.gov (United States)

Zhu, Dong; Hu, Fei; Wu, Liang; Li, Jun; Lang, Liang

2016-01-15

Mirrored interferometric aperture synthesis (MIAS) is a novel interferometry that can improve spatial resolution compared with that of conventional IAS. In one-dimensional (1-D) MIAS, antenna array with low redundancy has the potential to achieve a high spatial resolution. This Letter presents a technique for the direct construction of low-redundancy linear arrays (LRLAs) in MIAS and derives two regular analytical patterns that can yield various LRLAs in short computation time. Moreover, for a better estimation of the observed scene, a bi-measurement method is proposed to handle the rank defect associated with the transmatrix of those LRLAs. The results of imaging simulation demonstrate the effectiveness of the proposed method.

Interferometric data modelling: issues in realistic data generation

International Nuclear Information System (INIS)

Mukherjee, Soma

2004-01-01

This study describes algorithms developed for modelling interferometric noise in a realistic manner, i.e. incorporating non-stationarity that can be seen in the data from the present generation of interferometers. The noise model is based on individual component models (ICM) with the application of auto regressive moving average (ARMA) models. The data obtained from the model are vindicated by standard statistical tests, e.g. the KS test and Akaike minimum criterion. The results indicate a very good fit. The advantage of using ARMA for ICMs is that the model parameters can be controlled and hence injection and efficiency studies can be conducted in a more controlled environment. This realistic non-stationary noise generator is intended to be integrated within the data monitoring tool framework

All-optical phase modulation for integrated interferometric biosensors.

Science.gov (United States)

Dante, Stefania; Duval, Daphné; Sepúlveda, Borja; González-Guerrero, Ana Belen; Sendra, José Ramón; Lechuga, Laura M

2012-03-26

We present the theoretical and the experimental implementation of an all-optical phase modulation system in integrated Mach-Zehnder Interferometers to solve the drawbacks related to the periodic nature of the interferometric signal. Sensor phase is tuned by modulating the emission wavelength of low-cost commercial laser diodes by changing their output power. FFT deconvolution of the signal allows for direct phase readout, immune to sensitivity variations and to light intensity fluctuations. This simple phase modulation scheme increases the signal-to-noise ratio of the measurements in one order of magnitude, rendering in a sensor with a detection limit of 1.9·10⁻⁷ RIU. The viability of the all-optical modulation approach is demonstrated with an immunoassay detection as a biosensing proof of concept.

Modeling and Validation of Performance Limitations for the Optimal Design of Interferometric and Intensity-Modulated Fiber Optic Displacement Sensors

Energy Technology Data Exchange (ETDEWEB)

Moro, Erik A. [Los Alamos National Laboratory

2012-06-07

Optical fiber sensors offer advantages over traditional electromechanical sensors, making them particularly well-suited for certain measurement applications. Generally speaking, optical fiber sensors respond to a desired measurand through modulation of an optical signal's intensity, phase, or wavelength. Practically, non-contacting fiber optic displacement sensors are limited to intensity-modulated and interferometric (or phase-modulated) methodologies. Intensity-modulated fiber optic displacement sensors relate target displacement to a power measurement. The simplest intensity-modulated sensor architectures are not robust to environmental and hardware fluctuations, since such variability may cause changes in the measured power level that falsely indicate target displacement. Differential intensity-modulated sensors have been implemented, offering robustness to such intensity fluctuations, and the speed of these sensors is limited only by the combined speed of the photodetection hardware and the data acquisition system (kHz-MHz). The primary disadvantages of intensity-modulated sensing are the relatively low accuracy (?m-mm for low-power sensors) and the lack of robustness, which consequently must be designed, often with great difficulty, into the sensor's architecture. White light interferometric displacement sensors, on the other hand, offer increased accuracy and robustness. Unlike their monochromatic-interferometer counterparts, white light interferometric sensors offer absolute, unambiguous displacement measurements over large displacement ranges (cm for low-power, 5 mW, sources), necessitating no initial calibration, and requiring no environmental or feedback control. The primary disadvantage of white light interferometric displacement sensors is that their utility in dynamic testing scenarios is limited, both by hardware bandwidth and by their inherent high-sensitivity to Doppler-effects. The decision of whether to use either an intensity