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Sample records for vibratory seismic source

  1. Delineation of seismic source zones based on seismicity parameters ...

    Indian Academy of Sciences (India)

    The delineation of seismic source zones plays an important role in the evaluation of seismic hazard. In most of the studies the seismic source delineation is done based on geological features. In the present study, an attempt has been made to delineate seismic source zones in the study area (south India) based on the ...

  2. Perception of Frequency, Amplitude and Azimuth of a Vibratory Dipole-Source by the Octavolateralis System of Goldfish (Carassius auratus)

    Science.gov (United States)

    Dailey, Deena D.; Braun, Christopher B.

    2011-01-01

    Goldfish (Carassius auratus) were conditioned to suppress respiration to a 40 Hz vibratory source and subsequently tested for stimulus generalization to frequency, stimulus amplitude and position (azimuth). Animals completely failed to generalize to frequencies separated by octave intervals, both lesser and greater than the CS. However they did appear to generalize weakly to an aerial loudspeaker stimulus of the same frequency (40 Hz) after conditioning with an underwater vibratory source. Animals had a gradually decreasing amount of generalization to amplitude changes, suggesting a perceptual dimension of loudness. Animals generalized largely or completely to the same underwater source presented at a range of source azimuths. When these azimuths were presented at a transect of 3 cm, some animals did show decrements in generalization, while others did not. This suggests that although azimuth may be perceived more saliently at distances closer to a dipole source, perception of position is not immediately salient in conditioned vibratory source detection. Differential responding to test stimuli located towards the head or tail suggests the presence of perceptual differences between sources that are rostral or caudal with respect to the position of the animal or perhaps the head. PMID:21574689

  3. Controllable seismic source

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Antonio; DeRego, Paul Jeffrey; Ferrell, Patrick Andrew; Thom, Robert Anthony; Trujillo, Joshua J.; Herridge, Brian

    2015-09-29

    An apparatus for generating seismic waves includes a housing, a strike surface within the housing, and a hammer movably disposed within the housing. An actuator induces a striking motion in the hammer such that the hammer impacts the strike surface as part of the striking motion. The actuator is selectively adjustable to change characteristics of the striking motion and characteristics of seismic waves generated by the impact. The hammer may be modified to change the physical characteristics of the hammer, thereby changing characteristics of seismic waves generated by the hammer. The hammer may be disposed within a removable shock cavity, and the apparatus may include two hammers and two shock cavities positioned symmetrically about a center of the apparatus.

  4. Controllable seismic source

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Antonio; DeRego, Paul Jeffrey; Ferrel, Patrick Andrew; Thom, Robert Anthony; Trujillo, Joshua J.; Herridge, Brian

    2014-08-19

    An apparatus for generating seismic waves includes a housing, a strike surface within the housing, and a hammer movably disposed within the housing. An actuator induces a striking motion in the hammer such that the hammer impacts the strike surface as part of the striking motion. The actuator is selectively adjustable to change characteristics of the striking motion and characteristics of seismic waves generated by the impact. The hammer may be modified to change the physical characteristics of the hammer, thereby changing characteristics of seismic waves generated by the hammer. The hammer may be disposed within a removable shock cavity, and the apparatus may include two hammers and two shock cavities positioned symmetrically about a center of the apparatus.

  5. Comparison of seismic sources for shallow seismic: sledgehammer and pyrotechnics

    Directory of Open Access Journals (Sweden)

    Brom Aleksander

    2015-10-01

    Full Text Available The pyrotechnic materials are one of the types of the explosives materials which produce thermal, luminous or sound effects, gas, smoke and their combination as a result of a self-sustaining chemical reaction. Therefore, pyrotechnics can be used as a seismic source that is designed to release accumulated energy in a form of seismic wave recorded by tremor sensors (geophones after its passage through the rock mass. The aim of this paper was to determine the utility of pyrotechnics for shallow seismic engineering. The work presented comparing the conventional method of seismic wave excitation for seismic refraction method like plate and hammer and activating of firecrackers on the surface. The energy released by various sources and frequency spectra was compared for the two types of sources. The obtained results did not determine which sources gave the better results but showed very interesting aspects of using pyrotechnics in seismic measurements for example the use of pyrotechnic materials in MASW.

  6. Comparison of seismic sources for shallow seismic: sledgehammer and pyrotechnics

    Science.gov (United States)

    Brom, Aleksander; Stan-Kłeczek, Iwona

    2015-10-01

    The pyrotechnic materials are one of the types of the explosives materials which produce thermal, luminous or sound effects, gas, smoke and their combination as a result of a self-sustaining chemical reaction. Therefore, pyrotechnics can be used as a seismic source that is designed to release accumulated energy in a form of seismic wave recorded by tremor sensors (geophones) after its passage through the rock mass. The aim of this paper was to determine the utility of pyrotechnics for shallow seismic engineering. The work presented comparing the conventional method of seismic wave excitation for seismic refraction method like plate and hammer and activating of firecrackers on the surface. The energy released by various sources and frequency spectra was compared for the two types of sources. The obtained results did not determine which sources gave the better results but showed very interesting aspects of using pyrotechnics in seismic measurements for example the use of pyrotechnic materials in MASW.

  7. A simple structural power method for determining the vibratory strength of machinery sources

    DEFF Research Database (Denmark)

    Ohlrich, Mogens

    1998-01-01

    A new simple characterisation of the vibrational source strength of multi-terminal machinery is formulated in terms of a total terminal source power. This single power spectrum is determined from a summation of pairs of mean square velocities and point mobilities of the machine feet. The method...... this involves a multitude of interacting source and receiver variables, but from considerations on the randomness of interacting properties it is deduced that the total transmission essentially is controlled by simple relations. This is demonstrated for the two cases and it is revealed that this relation...... is a constant, frequency independent value, which means that the transmitted power at all frequencies is a constant fraction of the terminal source power spectrum of the machine....

  8. Seismic explosion sources on an ice cap

    DEFF Research Database (Denmark)

    Shulgin, Alexey; Thybo, Hans

    2015-01-01

    Controlled source seismic investigation of crustal structure below ice covers is an emerging technique. We have recently conducted an explosive refraction/wide-angle reflection seismic experiment on the ice cap in east-central Greenland. The data-quality is high for all shot points and a full...... crustal model can be modelled. A crucial challenge for applying the technique is to control the sources. Here, we present data that describe the efficiency of explosive sources in the ice cover. Analysis of the data shows, that the ice cap traps a significant amount of energy, which is observed...... as a strong ice wave. The ice cap leads to low transmission of energy into the crust such that charges need be larger than in conventional onshore experiments to obtain reliable seismic signals. The strong reflection coefficient at the base of the ice generates strong multiples which may mask for secondary...

  9. Genetics Home Reference: vibratory urticaria

    Science.gov (United States)

    ... Facebook Twitter Home Health Conditions vibratory urticaria vibratory urticaria Printable PDF Open All Close All Enable Javascript to view the expand/collapse boxes. Description Vibratory urticaria is a condition in which exposing the skin ...

  10. Development of a hydraulic borehole seismic source

    Energy Technology Data Exchange (ETDEWEB)

    Cutler, R.P.

    1998-04-01

    This report describes a 5 year, $10 million Sandia/Industry project to develop an advanced borehole seismic source for use in oil and gas exploration and production. The development Team included Sandia, Chevron, Amoco, Conoco, Exxon, Raytheon, Pelton, and GRI. The seismic source that was developed is a vertically oriented, axial point force, swept frequency, clamped, reaction-mass vibrator design. It was based on an early Chevron prototype, but the new tool incorporates a number of improvements which make it far superior to the original prototype. The system consists of surface control electronics, a special heavy duty fiber optic wireline and draw works, a cablehead, hydraulic motor/pump module, electronics module, clamp, and axial vibrator module. The tool has a peak output of 7,000 lbs force and a useful frequency range of 5 to 800 Hz. It can operate in fluid filled wells with 5.5-inch or larger casing to depths of 20,000 ft and operating temperatures of 170 C. The tool includes fiber optic telemetry, force and phase control, provisions to add seismic receiver arrays below the source for single well imaging, and provisions for adding other vibrator modules to the tool in the future. The project yielded four important deliverables: a complete advanced borehole seismic source system with all associated field equipment; field demonstration surveys funded by industry showing the utility of the system; industrial sources for all of the hardware; and a new service company set up by their industrial partner to provide commercial surveys.

  11. Seismic interferometry using multidimensional deconvolution and crosscorrelation for crosswell seismic reflection data without borehole sources

    NARCIS (Netherlands)

    Minato, S.; Matsuoka, T.; Tsuji, T.; Draganov, D.S.; Hunziker, J.W.; Wapenaar, C.P.A.

    2011-01-01

    Crosswell reflection method is a high-resolution seismic imaging method that uses recordings between boreholes. The need for downhole sources is a restrictive factor in its application, for example, to time-lapse surveys. An alternative is to use surface sources in combination with seismic

  12. New seismic source `BLASTER` for seismic survey; Hasaiyaku wo shingen to shite mochiita danseiha tansa

    Energy Technology Data Exchange (ETDEWEB)

    Koike, G.; Yoshikuni, Y. [OYO Corp., Tokyo (Japan)

    1996-10-01

    Built-up weight and vacuole have been conceived as seismic sources without using explosive. There have been problems that they have smaller energy to generate elastic wave than explosive, and that they have inferior working performance. Concrete crushing explosive is tried to use as a new seismic source. It is considered to possess rather large seismic generating energy, and it is easy to handle from the viewpoint of safety. Performance as seismic source and applicability to exploration works of this crushing explosive were compared with four kinds of seismic sources using dynamite, dropping weight, shot-pipe utilizing shot vacuole, and impact by wooden maul. When considered by the velocity amplitude, the seismic generating energy of the crushing explosive of 120 g is about one-fifth of dynamite of 100 g. Elastic wave generated includes less high frequency component than that by dynamite, and similar to that using seismic source without explosive, such as the weight dropping. The maximum seismic receiving distance obtained by the seismic generation was about 100 m. This was effective for the slope survey with the exploration depth between 20 m and 30 m. 1 ref., 9 figs., 2 tabs.

  13. Development of a magnetostrictive borehole seismic source

    Energy Technology Data Exchange (ETDEWEB)

    Cutler, R.P.; Sleefe, G.E.; Keefe, R.G.

    1997-04-01

    A magnetostrictive borehole seismic source was developed for use in high resolution crosswell surveys in environmental applications. The source is a clamped, vertical-shear, swept frequency, reaction-mass shaker design consisting of a spring pre-loaded magnetostrictive rod with permanent magnet bias, drive coils to induce an alternating magnetic field, and an integral tungsten reaction mass. The actuator was tested extensively in the laboratory. It was then incorporated into an easily deployable clamped downhole tool capable of operating on a standard 7 conductor wireline in borehole environments to 10,000{degrees} deep and 100{degrees}C. It can be used in either PVC or steel cased wells and the wells can be dry or fluid filled. It has a usable frequency spectrum of {approx} 150 to 2000 Hz. The finished tool was successfully demonstrated in a crosswell test at a shallow environmental site at Hanford, Washington. The source transmitted signals with a S/N ratio of 10-15 dB from 150-720 Hz between wells spaced 239 feet apart in unconsolidated gravel. The source was also tested successfully in rock at an oil field test site, transmitting signals with a S/N ratio of 5-15 dB over the full sweep spectrum from 150-2000 Hz between wells spaced 282 feet apart. And it was used successfully on an 11,000{degrees} wireline at a depth of 4550{degrees}. Recommendations for follow-on work include improvements to the clamp, incorporation of a higher sample rate force feedback controller, and increases in the force output of the tool.

  14. A vibratory micromechanical gyroscope

    Science.gov (United States)

    Boxenhorn, Burton; Greiff, Paul

    A novel vibratory micromechanical gyro with an active area less than one millimeter square has been analyzed, designed, and built. It has been demonstrated that such a gyro can be built using semiconductor fabrication techniques, and that the resulting performance is reasonably predictable. Further improvement of this gyro will result in an instrument that is small, low power, and in particular, will be very cheap in large quantitites.

  15. Open Source Seismic Hazard Analysis Software Framework (OpenSHA)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — OpenSHA is an effort to develop object-oriented, web- & GUI-enabled, open-source, and freely available code for conducting Seismic Hazard Analyses (SHA). Our...

  16. Seismic Sources Identification and Characterization for Myanmar: Towards Updating the Probabilistic Seismic Hazard Maps (2012)

    Science.gov (United States)

    Thant, M.; Kawase, H.

    2015-12-01

    Myanmar, lying in the Alpide earthquake belt, is quite earthquake-prone. There have been at least 16 major earthquakes (M 7.0 - 7.9) and a great earthquake (M 8.0, 1912) in the past 175 years, some of which were quite destructive, for example, 1839 Ava (Innwa) earthquake. With an objective of reducing earthquake risk in Myanmar, seismic zone maps have been constructed since 1959. The first-generation maps were mainly the intensity zoning maps using Modified Mercalli Intensity (MMI) Scales (Gorshkov, 1959; Maung Thein, 1985; Maung Thein, 2001). The second-generation maps were partly historical, and partly deterministic (Maung Thein et al., 2003; Maung Thein et al., 2005). In 2012, the third-generation maps, the probabilistic seismic hazard assessment (PSHA) maps were constructed for the whole country. Seismic hazards in these maps are represented by means of peak ground acceleration (PGA), peak ground velocity (PGV), and spectral acceleration (SA) in the periods of 0.2 s, 0.3 s and 1.0 s. The seismic hazards are calculated in 0.1° x 0.1° interval, assuming the firm rock site condition and all of the PSHA were carried out for 2% and 10% probability of exceedance in 50 years. Now, the seismic hazard maps of Myanmar,2012 are planned to update by remodeling the seismic sources. As the first step in updating the previous probabilistic seismic hazard maps developed in 2012 we re-identify the seismogenic sources for Indo-Burma Arc, Eastern Himalaya Arc and Andaman Rift Zone as the areal seismic sources. The major active faults which are seismically very hazardous for Myanmar: Sagaing fault, Kyaukkyan fault, Nan Pon fault, Kabaw fault, Myauk-U fault, Dawei fault, Gwegyo Thrust, major thrusts in north-west Myanmar, and the left-lateral strike-slip faults in the Eastern Highland are identified as the fault sources. The seismic source parameters for each source; the b-value, maximum earthquake potential, and annual rate of exceedance for the specific magnitude earthquake

  17. Stress-Release Seismic Source for Seismic Velocity Measurement in Mines

    Science.gov (United States)

    Swanson, P. L.; Clark, C.; Richardson, J.; Martin, L.; Zahl, E.; Etter, A.

    2014-12-01

    Accurate seismic event locations are needed to delineate roles of mine geometry, stress and geologic structures in developing rockburst conditions. Accurate absolute locations are challenging in mine environments with rapid changes in seismic velocity due to sharp contrasts between individual layers and large time-dependent velocity gradients attending excavations. Periodic use of controlled seismic sources can help constrain the velocity in this continually evolving propagation medium comprising the miners' workplace. With a view to constructing realistic velocity models in environments in which use of explosives is problematic, a seismic source was developed subject to the following design constraints: (i) suitable for use in highly disturbed zones surrounding mine openings, (ii) able to produce usable signals over km-scale distances in the frequency range of typical coal mine seismic events (~10-100 Hz), (iii) repeatable, (iv) portable, (v) non-disruptive to mining operations, and (vi) safe for use in potentially explosive gaseous environments. Designs of the compressed load column seismic source (CLCSS), which generates a stress, or load, drop normal to the surface of mine openings, and the fiber-optic based source-initiation timer are presented. Tests were conducted in a coal mine at a depth of 500 m (1700 ft) and signals were recorded on the surface with a 72-ch (14 Hz) exploration seismograph for load drops of 150-470 kN (16-48 tons). Signal-to-noise ratios of unfiltered signals ranged from ~200 immediately above the source (500 m (1700 ft)) to ~8 at the farthest extent of the array (slant distance of ~800 m (2600 ft)), suggesting the potential for use over longer range. Results are compared with signals produced by weight drop and sledge hammer sources, indicating the superior waveform quality for first-arrival measurements with the CLCSS seismic source.

  18. Back-Projecting Volcano and Geyser Seismic Signals to Sources

    Science.gov (United States)

    Kelly, C. L.; Lawrence, J. F.; Ebinger, C. J.

    2015-12-01

    Volcanic and hydrothermal systems are generally characterized by persistent, low-amplitude seismic "noise" with no clear onset or end. Outside of active eruptions and earthquakes, which tend to occur only a small fraction of the time, seismic records and spectrograms from these systems are dominated by long-duration "noise" (typically around 1-5Hz) generated by ongoing processes in the systems' subsurface. Although it has been shown that these low-amplitude signals can represent a series of overlapping low-magnitude displacements related to fluid and volatile movement at depth, because of their "noisy" properties compared to typical active or earthquake sources they are difficult to image using traditional seismic techniques (i.e. phase-picking). In this study we present results from applying a new ambient noise back-projection technique to improve seismic source imaging of diffuse signals found in volcanic and hydrothermal systems. Using this new method we show how the distribution of all seismic sources - particularly sources associated with volcanic tremor - evolves during a proposed intrusion in early June 2010 at Sierra Negra Volcano on the Galápagos Archipelago off the coast of Ecuador. We use a known velocity model for the region (Tepp et al., 2014) to correlate and back-project seismic signals from all available receiver-pairs to potential subsurface source locations assuming bending raypaths and accounting for topography. We generate 4D time-lapsed images of the source field around Sierra Negra before, during and after the proposed intrusion and compare the consistency of our observations with previously identified seismic event locations and tomography results from the same time period. Preliminary results from applying the technique to a dense grid of geophones surrounding a periodically erupting geyser at El Tatio Geyser Field in northern Chile (>2000 eruptions recorded) will also be presented.

  19. Earthquake sources and seismic hazard in Southeastern Sicily

    Directory of Open Access Journals (Sweden)

    R. Rigano

    2001-06-01

    Full Text Available A study of some earthquakes (M > 5.3 affecting Southeastern Sicily was performed to define their seismic sources and to estimate seismic hazard in the region. An analysis of historical reports allowed us to reassess intensities of the 1542, 1693, 1818, 1848 and 1990 earthquakes by using the new European Macroseismic Scale ’98. The new intensity data were used to define parameters and the orientation of seismic sources. The sources obtained were compared with the ones computed using the MCS intensities retrieved from the Catalogue of Strong Italian Earthquakes. The adopted procedure gives results that are statistically significant, but both the epicentre location and source azimuth, in some cases, are strongly affected by the azimuthal gap in the intensity distribution. This is evident mainly for the 1693 January earthquakes. For these earthquakes the macroseismic data uncertainty gives significantly different solutions, and does not allow the events to be associated with known active faults. By handling the new estimated intensity data and using the site seismic histories, the seismic hazard for some localities was calculated. The highest probability of occurrence, for destructive events (I = 10, was obtained in the area between Catania, Lentini and Augusta, suggesting that the seismogenic sources are located near the Ionian coast.

  20. Silicon Bulk Micromachined Vibratory Gyroscope

    Science.gov (United States)

    Tang, T. K.; Gutierrez, R. C.; Wilcox, J. Z.; Stell, C.; Vorperian, V.; Calvet, R.; Li, W. J.; Charkaborty, I.; Bartman, R.; Kaiser, W. J.

    1996-01-01

    This paper reports on design, modeling, fabrication, and characterization of a novel silicon bulk micromachined vibratory rate gyroscope designed for microspacecraft applications. The new microgyroscope consists of a silicon four leaf cloverstructure with a post attached to the center.

  1. Fully probabilistic seismic source inversion – Part 1: Efficient parameterisation

    Directory of Open Access Journals (Sweden)

    S. C. Stähler

    2014-11-01

    Full Text Available Seismic source inversion is a non-linear problem in seismology where not just the earthquake parameters themselves but also estimates of their uncertainties are of great practical importance. Probabilistic source inversion (Bayesian inference is very adapted to this challenge, provided that the parameter space can be chosen small enough to make Bayesian sampling computationally feasible. We propose a framework for PRobabilistic Inference of Seismic source Mechanisms (PRISM that parameterises and samples earthquake depth, moment tensor, and source time function efficiently by using information from previous non-Bayesian inversions. The source time function is expressed as a weighted sum of a small number of empirical orthogonal functions, which were derived from a catalogue of >1000 source time functions (STFs by a principal component analysis. We use a likelihood model based on the cross-correlation misfit between observed and predicted waveforms. The resulting ensemble of solutions provides full uncertainty and covariance information for the source parameters, and permits propagating these source uncertainties into travel time estimates used for seismic tomography. The computational effort is such that routine, global estimation of earthquake mechanisms and source time functions from teleseismic broadband waveforms is feasible.

  2. Theoretical gravitogram and gravito-gradiogram associated with seismic sources

    Science.gov (United States)

    Kimura, Masaya; Kame, Nobuki

    2017-04-01

    Seismic waves radiated from diverse source processes accompany density perturbations, which give rise to transient gravity perturbations. Here we present analytical expressions for theoretical gravitogram and gravito-gradiogram associated with seismic radiations from a single force or a seismic moment tensor in an infinite homogeneous elastic medium. Our expressions include whole time series from the instantaneous onset of gravity change to the static state. These formulae will functionally give template waveforms for the use of finding transient gravity changes in time-series data. As quantitative examples, we synthesize theoretical waveforms induced by the 2011 Tohoku-Oki earthquake (moment tensor) and by the 1980 St. Helens volcanic eruptions (single force), and examine their spatiotemporal characteristics. Other seismic sources, such as tensile cracking or CLVD (compensated linear vector dipole) in seismology are also within our scope though the corresponding prompt gravity signals are expected to be very small compared with the background seismic noise. In future the detection of the prompt gravity signals induced by earthquakes would become possible with high-sensitive measurements, which would give an earthquake and tsunami early-warning faster than the existing system based on the P-wave detection.

  3. Seismic and Biological Sources of Ambient Ocean Sound /

    OpenAIRE

    Freeman, Simon Eric

    2013-01-01

    Sound is the most efficient radiation in the ocean. Sounds of seismic and biological origin contain information regarding the underlying processes that created them. A single hydrophone records summary time-frequency information from the volume within acoustic range. Beamforming using a hydrophone array additionally produces azimuthal estimates of sound sources. A two-dimensional array and acoustic focusing produce an unambiguous two- dimensional `image' of sources. This dissertation describe...

  4. Seismic Prediction While Drilling (SPWD): Seismic exploration ahead of the drill bit using phased array sources

    Science.gov (United States)

    Jaksch, Katrin; Giese, Rüdiger; Kopf, Matthias

    2010-05-01

    In the case of drilling for deep reservoirs previous exploration is indispensable. In recent years the focus shifted more on geological structures like small layers or hydrothermal fault systems. Beside 2D- or 3D-seismics from the surface and seismic measurements like Vertical Seismic Profile (VSP) or Seismic While Drilling (SWD) within a borehole these methods cannot always resolute this structures. The resolution is worsen the deeper and smaller the sought-after structures are. So, potential horizons like small layers in oil exploration or fault zones usable for geothermal energy production could be failed or not identified while drilling. The application of a device to explore the geology with a high resolution ahead of the drill bit in direction of drilling would be of high importance. Such a device would allow adjusting the drilling path according to the real geology and would minimize the risk of discovery and hence the costs for drilling. Within the project SPWD a device for seismic exploration ahead of the drill bit will be developed. This device should allow the seismic exploration to predict areas about 50 to 100 meters ahead of the drill bit with a resolution of one meter. At the GFZ a first prototype consisting of different units for seismic sources, receivers and data loggers has been designed and manufactured. As seismic sources four standard magnetostrictive actuators and as receivers four 3-component-geophones are used. Every unit, actuator or geophone, can be rotated in steps of 15° around the longitudinal axis of the prototype to test different measurement configurations. The SPWD prototype emits signal frequencies of about 500 up to 5000 Hz which are significant higher than in VSP and SWD. An increased radiation of seismic wave energy in the direction of the borehole axis allows the view in areas to be drilled. Therefore, every actuator must be controlled independently of each other regarding to amplitude and phase of the source signal to

  5. Fast Bayesian Optimal Experimental Design for Seismic Source Inversion

    KAUST Repository

    Long, Quan

    2016-01-06

    We develop a fast method for optimally designing experiments [1] in the context of statistical seismic source inversion [2]. In particular, we efficiently compute the optimal number and locations of the receivers or seismographs. The seismic source is modeled by a point moment tensor multiplied by a time-dependent function. The parameters include the source location, moment tensor components, and start time and frequency in the time function. The forward problem is modeled by the elastic wave equations. We show that the Hessian of the cost functional, which is usually defined as the square of the weighted L2 norm of the difference between the experimental data and the simulated data, is proportional to the measurement time and the number of receivers. Consequently, the posterior distribution of the parameters, in a Bayesian setting, concentrates around the true parameters, and we can employ Laplace approximation and speed up the estimation of the expected Kullback-Leibler divergence (expected information gain), the optimality criterion in the experimental design procedure. Since the source parameters span several magnitudes, we use a scaling matrix for efficient control of the condition number of the original Hessian matrix. We use a second-order accurate finite difference method to compute the Hessian matrix and either sparse quadrature or Monte Carlo sampling to carry out numerical integration. We demonstrate the efficiency, accuracy, and applicability of our method on a two-dimensional seismic source inversion problem.

  6. Fast Bayesian optimal experimental design for seismic source inversion

    KAUST Repository

    Long, Quan

    2015-07-01

    We develop a fast method for optimally designing experiments in the context of statistical seismic source inversion. In particular, we efficiently compute the optimal number and locations of the receivers or seismographs. The seismic source is modeled by a point moment tensor multiplied by a time-dependent function. The parameters include the source location, moment tensor components, and start time and frequency in the time function. The forward problem is modeled by elastodynamic wave equations. We show that the Hessian of the cost functional, which is usually defined as the square of the weighted L2 norm of the difference between the experimental data and the simulated data, is proportional to the measurement time and the number of receivers. Consequently, the posterior distribution of the parameters, in a Bayesian setting, concentrates around the "true" parameters, and we can employ Laplace approximation and speed up the estimation of the expected Kullback-Leibler divergence (expected information gain), the optimality criterion in the experimental design procedure. Since the source parameters span several magnitudes, we use a scaling matrix for efficient control of the condition number of the original Hessian matrix. We use a second-order accurate finite difference method to compute the Hessian matrix and either sparse quadrature or Monte Carlo sampling to carry out numerical integration. We demonstrate the efficiency, accuracy, and applicability of our method on a two-dimensional seismic source inversion problem. © 2015 Elsevier B.V.

  7. Seismic Interferometry Using Persistent Noise Sources for Temporal Subsurface Monitoring

    Science.gov (United States)

    Dales, Philippe; Audet, Pascal; Olivier, Gerrit

    2017-11-01

    In passive source seismology, seismic interferometry typically refers to the cross correlation of ambient noise to construct an estimate of the Green's function between sensors. The presence of persistent natural and/or anthropogenic sources can bias or prevent the retrieval of these estimated Green's functions. Here we show how these strong persistent sources can be used to measure small changes in the medium between a source and either (or both) source-sensor pairs. The method relies on localizing the sources and using this information to identify and select cross-correlation functions for each source of interest. We illustrate this method by monitoring growth of a block cave at an underground mine using three nearly continuously operating ore crushers which dominate the wavefield. This technique should work equally well in natural environments using sources such as volcanic tremor, hydrothermal bubble cavitation, and microseisms.

  8. Seismic source characterisation of a Tunnel Boring Machine (TBM)

    Science.gov (United States)

    Kreutzer, Ingrid; Brückl, Ewald; Radinger, Alexander

    2015-04-01

    The Tunnel Seismic While Drilling (TSWD) method aims at predicting continuously the geological situation ahead of the tunnel without disturbing the construction work. Thereby the Tunnel Boring Machine (TBM) itself is used as seismic source. The cutting process generates seismic waves radiating into the rock mass and vibrations propagating to the main bearing of the cutter head. These vibrations are monitored and used as pilot signal. For the processing and interpretation it was hypothesized so far that the TBM acts like a single force. To prove this assumption the radiation pattern of several TBM's under construction were investigated. Therefore 3-components geophones were installed at the surface, which were situated directly above the tunnel axes and also with lateral offset. Additional, borehole geophones were placed in the wall of one tube of a two-tube tunnel. The geophones collected the forward and backward radiated wave field, as the TBM, operating in the other tube, passed their positions. The obtained seismic data contains continuous records over a range of 600 m of the TBM position. The offsets vary from 25 m to 400 m and the frequency ranges from 20-250 Hertz. The polarisation of the p-wave and the s-wave and their amplitude ratio were determined and compared with modelled seismograms with different source mechanism. The results show that the description of the source mechanism by a single force can be used as a first order approximation. More complex radiation pattern including tensile forces and several source locations like the transmission of reaction forces over the gripper to the tunnel wall are further tested and addressed.

  9. Seismic and Biological Sources of Ambient Ocean Sound

    Science.gov (United States)

    Freeman, Simon Eric

    Sound is the most efficient radiation in the ocean. Sounds of seismic and biological origin contain information regarding the underlying processes that created them. A single hydrophone records summary time-frequency information from the volume within acoustic range. Beamforming using a hydrophone array additionally produces azimuthal estimates of sound sources. A two-dimensional array and acoustic focusing produce an unambiguous two-dimensional `image' of sources. This dissertation describes the application of these techniques in three cases. The first utilizes hydrophone arrays to investigate T-phases (water-borne seismic waves) in the Philippine Sea. Ninety T-phases were recorded over a 12-day period, implying a greater number of seismic events occur than are detected by terrestrial seismic monitoring in the region. Observation of an azimuthally migrating T-phase suggests that reverberation of such sounds from bathymetric features can occur over megameter scales. In the second case, single hydrophone recordings from coral reefs in the Line Islands archipelago reveal that local ambient reef sound is spectrally similar to sounds produced by small, hard-shelled benthic invertebrates in captivity. Time-lapse photography of the reef reveals an increase in benthic invertebrate activity at sundown, consistent with an increase in sound level. The dominant acoustic phenomenon on these reefs may thus originate from the interaction between a large number of small invertebrates and the substrate. Such sounds could be used to take census of hard-shelled benthic invertebrates that are otherwise extremely difficult to survey. A two-dimensional `map' of sound production over a coral reef in the Hawaiian Islands was obtained using two-dimensional hydrophone array in the third case. Heterogeneously distributed bio-acoustic sources were generally co-located with rocky reef areas. Acoustically dominant snapping shrimp were largely restricted to one location within the area surveyed

  10. Drawing a Seismic Source Zone Model Using Cumulative Seismic Moment Release and Moment Tensors in the Italian Peninsula

    Science.gov (United States)

    Salimbeni, S.; Pondrelli, S.; D'Amico, V.; Meletti, C.; Rovida, A.

    2016-12-01

    In the frame of the elaboration of a new seismic hazard model of Italy, the identification of the areas with homogeneous tectonic regime is needed as one of the objective elements for designing the seismic source zones.A collection of all seismic moment tensors available for Italy for earthquakes with magnitude greater than or equal to 4.0 since 1960 was gathered. It contains data from different catalogs or datasets, mainly populated by moment tensors computed through inversion of seismic waves (e.g. CMT, RCMT, GFZ and ETHZ MT and so on). However, for great earthquakes of the past, i.e. the 1962 Irpinia or the 1968 Belice earthquakes (both max Mw > 6.0) we used data obtained with other methods, but always considered the best available information for that time.All these data helped to find the predominant fault mechanism, considered the typical tectonic style for a region or, using regular grids, for all seismic areas of the Italian peninsula and regions around. To identify the most seismic regions, we used data from historical and recent instrumental seismicity (CPTI15, http://emidius.mi.ingv.it/CPTI15-DBMI15/ and INGV bulletins, http://iside.rm.ingv.it/) combined on a regular grid, obtaining seismic moment release maps. Overlapping cumulative moment tensors to seismic moment release maps, we identified regions clearly characterized by different tectonics. In particular, the extension is the principal type of deformation along most of the Apennines, somewhere interrupted by strike-slip mechanism. Compressive deformation appears in the eastern Alps, in the outer part of the northernmost sector of the Apennines, in several parts of the Adriatic Sea and in the off shore of Northern Sicily. We considered this tectonic style mapping to help with drawing seismic area sources for the new seismic hazard model of Italy.

  11. Test to Extract Soil Properties Using the Seismic HammerTM Active Seismic Source

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Rebekah F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Abbott, Robert E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-08-01

    Geologic material properties are necessary parameters for ground motion modeling and are difficult and expensive to obtain via traditional methods. Alternative methods to estimate soil properties require a measurement of the ground's response to a force. A possible method of obtaining these measurements is active-source seismic surveys, but measurements of the ground response at the source must also be available. The potential of seismic sources to obtain soil properties is limited, however, by the repeatability of the source. Explosives, and hammer surveys are not repeatable because of variable ground coupling or swing strength. On the other hand, the Seismic Hammer TM (SH) is consistent in the amount of energy it inputs into the ground. In addition, it leaves large physical depressions as a result of ground compaction. The volume of ground compaction varies by location. Here, we hypothesize that physical depressions left in the earth by the SH correlate to energy recorded by nearby geophones, and therefore are a measurement of soil physical properties. Using measurements of the volume of shot holes, we compare the spatial distribution of the volume of ground compacted between the different shot locations. We then examine energy recorded by the nearest 50 geophones and compare the change in amplitude across hits at the same location. Finally, we use the percent difference between the energy recorded by the first and later hits at a location to test for a correlation to the volume of the shot depressions. We find that: * Ground compaction at the shot-depression does cluster geographically, but does not correlate to known surface features. * Energy recorded by nearby geophones reflects ground refusal after several hits. * There is no correlation to shot volume and changes in energy at particular shot locations. Deeper material properties (i.e. below the depth of surface compaction) may be contributing to the changes in energy propagation. * Without further

  12. The Feasibility of Monitoring Continuous Wave Sources with Seismic Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Claassen, J.P.; Elbring, G.; Ladd, M.

    1999-03-15

    This paper identifies and explores the technical requirements and issues associated with remotely monitoring continuous wave (CW) sources with seismic arrays. Potential approaches to this monitoring problem will be suggested and partially evaluated to expose the monitoring challenges which arise when realistic local geologies and cultural noise sources are considered. The selective directionality and the adaptive noise cancellation properties of arrays are required to observe weak signals while suppressing a colored background punctuated with an unknown distribution of point and sometimes distributive sources. The array is also required to characterize the emitters and propagation environment so as to properly focus on the CW sources of interest while suppressing the remaining emitters. The proper application of arrays requires an appreciation of the complexity of propagation in a non-homogeneous earth. The heterogeneity often limits the available spatial coherence and therefore the size of the army. This adversely impacts the array gain and the array's ability to carefully resolve various emitters. Arrays must also contend with multipath induced by the source and the heterogeneous earth. If the array is to focus on an emitter and realize an enhancement in the signal to noise ratio, methods must be sought to coherently add the desired signal components while suppressing interference which may be correlated with the desired signal. The impact of these and other issues on army design and processing are described and discussed.

  13. Analysis and Simulation of Far-Field Seismic Data from the Source Physics Experiment

    Science.gov (United States)

    2012-09-01

    seismic moment Mo=2.0×1012 Nm. Several simulations were run to investigate the effect of source time function, velocity variations, and surface...Vp= 5000m /s, Vs=2900 m/s and density=2.5 g/cm3 produced the same results as simulations with a Gaussian source time function and a seismic moment Mo

  14. Controlled-source seismic reflection interferometry : Virtual-source retrieval, survey infill and identification of surface multiples

    NARCIS (Netherlands)

    Boullenger, B.

    2017-01-01

    The theory of seismic interferometry predicts that the cross-correlation (and possibly summation) between seismic recordings at two separate receivers allows the retrieval of an estimate of the inter-receiver response, or Green's function, from a virtual source at one of the receiver positions.

  15. Error Model and Compensation of Bell-Shaped Vibratory Gyro

    OpenAIRE

    Zhong Su; Ning Liu; Qing Li

    2015-01-01

    A bell-shaped vibratory angular velocity gyro (BVG), inspired by the Chinese traditional bell, is a type of axisymmetric shell resonator gyroscope. This paper focuses on development of an error model and compensation of the BVG. A dynamic equation is firstly established, based on a study of the BVG working mechanism. This equation is then used to evaluate the relationship between the angular rate output signal and bell-shaped resonator character, analyze the influence of the main error source...

  16. Seismic source zone characterization for the seismic hazard assessment project PEGASOS by the Expert Group 2 (EG1b)

    Energy Technology Data Exchange (ETDEWEB)

    Burkhard, M. [Institut de Geologie, Universite de Neuchatel, Neuchatel (Switzerland); Gruenthal, G. [GFZ German Research Centre for Geosciences, Telegrafenberg, Potsdam (Germany)

    2009-05-15

    A comprehensive study of the seismic hazard related to the four NNP sites in NW Switzerland was performed within the project PEGASOS. To account for the epistemic uncertainties involved in the process of the characterization of seismic source zones in the frame of probabilistic seismic hazard assessments, four different expert teams have developed and defended their models in the frame of an intensive elicitation process. Here, the results of one out of four expert groups are presented. The model of this team is based first of all on considerations regarding the large scale tectonics in the context of the Alpine collision, and neotectonic constraints for defining seismic source zones. This leads to a large scale subdivision based on the structural 'architectural' considerations with little input from the present seismicity. Each of the eight large zones was characterized by the style of present-day faulting, fault orientation, and hypo central depth distribution. A further subdivision of the larger zones is performed based on information provided by the seismicity patterns. 58 small source zones have been defined in this way, each of them characterized by the available tectonic constrains, as well as the pros and cons of different existing geologic views connected to them. Of special concern in this respect were the discussion regarding thin skinned vs. thick skinned tectonics, the tectonic origin of the 1356 Basel earthquake, the role of the Permo-Carboniferous graben structures, and finally the seismogenic orientation of faults with respect to the recent crustal stress field. The uncertainties connected to the delimitations of the small source zones have been handled in form of their regrouping, formalized by the logic tree technique. The maximum magnitudes were estimated as discretized probability distribution functions. After de-clustering the used ECOS earthquake catalogue and an analysis of data completeness as a function of time the parameters of

  17. GEC Ferranti piezo vibratory gyroscope

    Science.gov (United States)

    Nuttall, J. D.

    1993-01-01

    Prototypes of a piezo-electric vibratory angular rate transducer (gyroscope) (PVG) have been constructed and evaluated. The construction is on the lines suggested by Burdess. The sensitive element is a cylinder of radially poled piezo-electric ceramic. The cylinder is metallized inside and out, and the outer metallization is divided into eight electrodes. The metallization on the inside is earthed. A phase locked loop, using pairs of the electrodes, causes the cylinder to vibrate in one of its two fundamental, degenerate modes. In the presence of rotation, some of the vibration is coupled into the outer mode. This can be detected, or suppressed with a closed-up technique and provides a measure of rotation rate. The gyroscope provides a number of advantages over rotating mass and optical instruments: low size and mass, lower power consumption, potentially high reliability, potentially good dormancy, low cost and high maximum rate.

  18. GDP: A new source for shallow high-resolution seismic exploration

    Science.gov (United States)

    Rashed, Mohamed A.

    2009-06-01

    Gas-Driven Piston (GDP) is a new source for shallow seismic exploration. This source works by igniting a small amount of gas inside a closed chamber connected to a vertical steel cylinder. The gas explosion drives a steel piston, mounted inside the cylinder, downward so that the piston's thick head hits a steel base at the end of the cylinder generating a strong shock wave into the ground. Experimental field tests conducted near Ismailia, Egypt, prove that the portable, inexpensive and environmentally benign GDP generates stronger seismic waves than the sledgehammer that is commonly used in shallow seismic exploration. Tests also show that GDP is a highly repeatable and controllable and that its seismic waves contain a good amount of high frequencies which makes the GDP an excellent source for shallow seismic exploration.

  19. Model Based Beamforming and Bayesian Inversion Signal Processing Methods for Seismic Localization of Underground Source

    DEFF Research Database (Denmark)

    Oh, Geok Lian

    This PhD study examines the use of seismic technology for the problem of detecting underground facilities, whereby a seismic source such as a sledgehammer is used to generate seismic waves through the ground, sensed by an array of seismic sensors on the ground surface, and recorded by the digital...... properties such as the elastic wave speeds and soil densities. One processing method is casting the estimation problem into an inverse problem to solve for the unknown material parameters. The forward model for the seismic signals used in the literatures include ray tracing methods that consider only...... the first arrivals of the reflected compressional P-waves from the subsurface structures, or 3D elastic wave models that model all the seismic wave components. The ray tracing forward model formulation is linear, whereas the full 3D elastic wave model leads to a nonlinear inversion problem. In this Ph...

  20. Method for enhancing low frequency output of impulsive type seismic energy sources and its application to a seismic energy source for use while drilling

    Science.gov (United States)

    Radtke, Robert P; Stokes, Robert H; Glowka, David A

    2014-12-02

    A method for operating an impulsive type seismic energy source in a firing sequence having at least two actuations for each seismic impulse to be generated by the source. The actuations have a time delay between them related to a selected energy frequency peak of the source output. One example of the method is used for generating seismic signals in a wellbore and includes discharging electric current through a spark gap disposed in the wellbore in at least one firing sequence. The sequence includes at least two actuations of the spark gap separated by an amount of time selected to cause acoustic energy resulting from the actuations to have peak amplitude at a selected frequency.

  1. Utilization of near-source video and ground motion in the assessment of seismic source functions from mining explosions

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, D.P. [Southern Methodist Univ., Dallas, TX (United States). Dept. of Geological Sciences; Stump, B.W. [Los Alamos National Lab., NM (United States)

    1994-09-01

    Identification of seismic events detected under a Comprehensive Test Ban Treaty requires a clear physical understanding of the different types of seismic sources including mining explosions, rock bursts, mine collapse and small, shallow earthquakes. Constraint of the operative physical processes in the source region and linkage to the generation of seismic waveforms with particular emphasis on regional seismograms is needed. In order to properly address the multi-dimensional aspect of data sets designed to constrain these sources, we are investigating a number of modern visualization tools that have only recently become available with new, high-speed graphical computers that can utilize relatively large data sets. The results of this study will provide a basis for identifying important processes in the source region that contribute to regional seismograms.

  2. Theoretical basis of the amplitude source location method for volcano-seismic signals

    Science.gov (United States)

    Morioka, Hanae; Kumagai, Hiroyuki; Maeda, Takuto

    2017-08-01

    The source location method using high-frequency seismic amplitudes based on the assumption of isotropic radiation of S waves has been used successfully to locate seismic events and tremor at volcanoes. This amplitude source location (ASL) method overcomes the limitations of traditional hypocenter determination methods that use onset arrival times and has great potential to improve volcano-seismic monitoring and the investigation of source processes of volcano-seismic signals. However, theoretical justification of the basic assumption used in the ASL method has not been provided in previous studies. In this study, we tested the ASL method by using seismic waveforms simulated with a finite difference method in realistic heterogeneous volcanic structures with intrinsic attenuation and topography. Our results showed that ASL determinations were successful when using waveforms characterized by multiple scattering that can be approximated by the diffusion model. We found that the energy solution of the diffusion model provided an amplitude-distance relation that is similar to that used in the ASL method. Our results suggest that the ASL method is applicable to high-frequency seismograms in highly heterogeneous media with transport mean free paths of 103 m or smaller and strong intrinsic attenuation. These medium parameters are consistent with those estimated at various volcanoes. Our study validates the basic assumption of the ASL method and justifies its use to locate the sources of high-frequency seismic signals observed at volcanoes.

  3. DETERMINATION OF COORDINATES OF SEISMIC WAVE SOURCE BY AMPLITUDE METHOD OF PASSIVE LOCATION

    Directory of Open Access Journals (Sweden)

    Vasily D. Syten’ky

    2012-01-01

    Full Text Available The paper presents results of the mathematical synthesis of the method of passive location of a seismic wave source. The method employs measurements of regular attenuation of seismic oscillation amplitudes. If it is impossible to determine the location of a seismic event by means of direct measurements, indirect measurements are needed. A priori information for the mathematical synthesis was obtained from functional equations showing inverse proportions of measured amplitudes, arbitrary effective attenuation coefficients and corresponding coordinates. An original method was applied to process the data. The method providing for passive location of seismic waves sources has been developed; it is called the radial basic method. In the one-dimensional case, a distance is determined on the basis of seismic oscillation amplitudes measured by two seismographs that are located at a known base distance coinciding with the direction to the source of seismic waves. The distance is calculated from the receiver that is nearest to the source. If the base distance and the direct line between the seismograph and the seismic wave source do not coincide, a projection of the distance between the receivers to the given straight line is taken into account.Three seismographs were placed at mutually perpendicular base distances in a plane (i.e. the two-dimensional space. This allowed us to obtain an analytical equation for determining the direction to the seismic wave source using measured amplitudes. The value of the angle is taken into account when calculating the distance.For the seismic wave source located in the three-dimensional space, transition equations for combined coordinate systems (i.e. the Descartes (Cartesian, at the axes of which the seismographs were placed, and the spherical coordinate systems were applied, and analytical equations were obtained for determination of coordinates, such as distance/polar radius, elevation

  4. DETERMINATION OF COORDINATES OF SEISMIC WAVE SOURCE BY AMPLITUDE METHOD OF PASSIVE LOCATION

    Directory of Open Access Journals (Sweden)

    Vasily D. Syten’ky

    2015-10-01

    Full Text Available The paper presents results of the mathematical synthesis of the method of passive location of a seismic wave source. The method employs measurements of regular attenuation of seismic oscillation amplitudes. If it is impossible to determine the location of a seismic event by means of direct measurements, indirect measurements are needed. A priori information for the mathematical synthesis was obtained from functional equations showing inverse proportions of measured amplitudes, arbitrary effective attenuation coefficients and corresponding coordinates. An original method was applied to process the data. The method providing for passive location of seismic waves sources has been developed; it is called the radial basic method. In the one-dimensional case, a distance is determined on the basis of seismic oscillation amplitudes measured by two seismographs that are located at a known base distance coinciding with the direction to the source of seismic waves. The distance is calculated from the receiver that is nearest to the source. If the base distance and the direct line between the seismograph and the seismic wave source do not coincide, a projection of the distance between the receivers to the given straight line is taken into account.Three seismographs were placed at mutually perpendicular base distances in a plane (i.e. the two-dimensional space. This allowed us to obtain an analytical equation for determining the direction to the seismic wave source using measured amplitudes. The value of the angle is taken into account when calculating the distance.For the seismic wave source located in the three-dimensional space, transition equations for combined coordinate systems (i.e. the Descartes (Cartesian, at the axes of which the seismographs were placed, and the spherical coordinate systems were applied, and analytical equations were obtained for determination of coordinates, such as distance/polar radius, elevation

  5. pySeismicDQA: open source post experiment data quality assessment and processing

    Science.gov (United States)

    Polkowski, Marcin

    2017-04-01

    Seismic Data Quality Assessment is python based, open source set of tools dedicated for data processing after passive seismic experiments. Primary goal of this toolset is unification of data types and formats from different dataloggers necessary for further processing. This process requires additional data checks for errors, equipment malfunction, data format errors, abnormal noise levels, etc. In all such cases user needs to decide (manually or by automatic threshold) if data is removed from output dataset. Additionally, output dataset can be visualized in form of website with data availability charts and waveform visualization with earthquake catalog (external). Data processing can be extended with simple STA/LTA event detection. pySeismicDQA is designed and tested for two passive seismic experiments in central Europe: PASSEQ 2006-2008 and "13 BB Star" (2013-2016). National Science Centre Poland provided financial support for this work via NCN grant DEC-2011/02/A/ST10/00284.

  6. Post-blasting seismicity in Rudna copper mine, Poland - source parameters analysis.

    Science.gov (United States)

    Caputa, Alicja; Rudziński, Łukasz; Talaga, Adam

    2017-04-01

    The really important hazard in Polish copper mines is high seismicity and corresponding rockbursts. Many methods are used to reduce the seismic hazard. Among others the most effective is preventing blasting in potentially hazardous mining panels. The method is expected to provoke small moderate tremors (up to M2.0) and reduce in this way a stress accumulation in the rockmass. This work presents an analysis, which deals with post-blasting events in Rudna copper mine, Poland. Using the Full Moment Tensor (MT) inversion and seismic spectra analysis, we try to find some characteristic features of post blasting seismic sources. Source parameters estimated for post-blasting events are compared with the parameters of not-provoked mining events that occurred in the vicinity of the provoked sources. Our studies show that focal mechanisms of events which occurred after blasts have similar MT decompositions, namely are characterized by a quite strong isotropic component as compared with the isotropic component of not-provoked events. Also source parameters obtained from spectral analysis show that provoked seismicity has a specific source physics. Among others, it is visible from S to P wave energy ratio, which is higher for not-provoked events. The comparison of all our results reveals a three possible groups of sources: a) occurred just after blasts, b) occurred from 5min to 24h after blasts and c) not-provoked seismicity (more than 24h after blasting). Acknowledgements: This work was supported within statutory activities No3841/E-41/S/2016 of Ministry of Science and Higher Education of Poland.

  7. Large-N Seismic Deployment at the Source Physics Experiment (SPE) Site

    Science.gov (United States)

    Chen, T.; Snelson, C. M.; Mellors, R. J.; Pitarka, A.

    2015-12-01

    The Source Physics Experiment (SPE) is multi-institutional and multi-disciplinary project that consists of a series of chemical explosion experiments at the Nevada National Security Site. The goal of SPE is to understand the complicated effect of earth structures on source energy partitioning and seismic wave propagation, develop and validate physics-based monitoring, and ultimately better discriminate low-yield nuclear explosions from background seismicity. Deployment of a large number of seismic sensors is planned for SPE to image the full 3-D wavefield with about 500 three-component sensors and 500 vertical component sensors. This large-N seismic deployment will operate near the site of SPE-5 shot for about one month, recording the SPE-5 shot, ambient noise, and additional controlled-sources. This presentation focuses on the design of the large-N seismic deployment. We show how we optimized the sensor layout based on the geological structure and experiment goals with a limited number of sensors. In addition, we will also show some preliminary record sections from deployment. This work was conducted under Contract No. DE-AC52-06NA25946 with the U.S. Department of Energy.

  8. High-resolution and super stacking of time-reversal mirrors in locating seismic sources

    KAUST Repository

    Cao, Weiping

    2011-07-08

    Time reversal mirrors can be used to backpropagate and refocus incident wavefields to their actual source location, with the subsequent benefits of imaging with high-resolution and super-stacking properties. These benefits of time reversal mirrors have been previously verified with computer simulations and laboratory experiments but not with exploration-scale seismic data. We now demonstrate the high-resolution and the super-stacking properties in locating seismic sources with field seismic data that include multiple scattering. Tests on both synthetic data and field data show that a time reversal mirror has the potential to exceed the Rayleigh resolution limit by factors of 4 or more. Results also show that a time reversal mirror has a significant resilience to strong Gaussian noise and that accurate imaging of source locations from passive seismic data can be accomplished with traces having signal-to-noise ratios as low as 0.001. Synthetic tests also demonstrate that time reversal mirrors can sometimes enhance the signal by a factor proportional to the square root of the product of the number of traces, denoted as N and the number of events in the traces. This enhancement property is denoted as super-stacking and greatly exceeds the classical signal-to-noise enhancement factor of. High-resolution and super-stacking are properties also enjoyed by seismic interferometry and reverse-time migration with the exact velocity model. © 2011 European Association of Geoscientists & Engineers.

  9. Seismic and source characteristics of large chemical explosions. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Adushkin, V.V.; Kostuchenko, V.N.; Pernik, L.M.; Sultanov, D.D.; Zcikanovsky, V.I.

    1995-01-01

    From the very beginning of its arrangement in 1947, the Institute for Dynamics of the Geospheres RAS (former Special Sector of the Institute for physics of the Earth, RAS) was providing scientific observations of effects of nuclear explosions, as well as large-scale detonations of HE, on environment. This report presents principal results of instrumental observations obtained from various large-scale chemical explosions conducted in the Former-Soviet Union in the period of time from 1957 to 1989. Considering principal aim of the work, tamped and equivalent chemical explosions have been selected with total weights from several hundreds to several thousands ton. In particular, the selected explosions were aimed to study scaling law from excavation explosions, seismic effect of tamped explosions, and for dam construction for hydropower stations and soil melioration. Instrumental data on surface explosions of total weight in the same range aimed to test military technics and special objects are not included.

  10. Added-value joint source modelling of seismic and geodetic data

    Science.gov (United States)

    Sudhaus, Henriette; Heimann, Sebastian; Walter, Thomas R.; Krueger, Frank

    2013-04-01

    In tectonically active regions earthquake source studies strongly support the analysis of the current faulting processes as they reveal the location and geometry of active faults, the average slip released or more. For source modelling of shallow, moderate to large earthquakes often a combination of geodetic (GPS, InSAR) and seismic data is used. A truly joint use of these data, however, usually takes place only on a higher modelling level, where some of the first-order characteristics (time, centroid location, fault orientation, moment) have been fixed already. These required basis model parameters have to be given, assumed or inferred in a previous, separate and highly non-linear modelling step using one of the these data sets alone. We present a new earthquake rupture model implementation that realizes a fully combined data integration of surface displacement measurements and seismic data in a non-linear optimization of simple but extended planar ruptures. The model implementation allows for fast forward calculations of full seismograms and surface deformation and therefore enables us to use Monte Carlo global search algorithms. Furthermore, we benefit from the complementary character of seismic and geodetic data, e. g. the high definition of the source location from geodetic data and the sensitivity of the resolution of the seismic data on moment releases at larger depth. These increased constraints from the combined dataset make optimizations efficient, even for larger model parameter spaces and with a very limited amount of a priori assumption on the source. A vital part of our approach is rigorous data weighting based on the empirically estimated data errors. We construct full data error variance-covariance matrices for geodetic data to account for correlated data noise and also weight the seismic data based on their signal-to-noise ratio. The estimation of the data errors and the fast forward modelling opens the door for Bayesian inferences of the source

  11. High temporal resolution mapping of seismic noise sources using heterogeneous supercomputers

    Science.gov (United States)

    Gokhberg, Alexey; Ermert, Laura; Paitz, Patrick; Fichtner, Andreas

    2017-04-01

    Time- and space-dependent distribution of seismic noise sources is becoming a key ingredient of modern real-time monitoring of various geo-systems. Significant interest in seismic noise source maps with high temporal resolution (days) is expected to come from a number of domains, including natural resources exploration, analysis of active earthquake fault zones and volcanoes, as well as geothermal and hydrocarbon reservoir monitoring. Currently, knowledge of noise sources is insufficient for high-resolution subsurface monitoring applications. Near-real-time seismic data, as well as advanced imaging methods to constrain seismic noise sources have recently become available. These methods are based on the massive cross-correlation of seismic noise records from all available seismic stations in the region of interest and are therefore very computationally intensive. Heterogeneous massively parallel supercomputing systems introduced in the recent years combine conventional multi-core CPU with GPU accelerators and provide an opportunity for manifold increase and computing performance. Therefore, these systems represent an efficient platform for implementation of a noise source mapping solution. We present the first results of an ongoing research project conducted in collaboration with the Swiss National Supercomputing Centre (CSCS). The project aims at building a service that provides seismic noise source maps for Central Europe with high temporal resolution (days to few weeks depending on frequency and data availability). The service is hosted on the CSCS computing infrastructure; all computationally intensive processing is performed on the massively parallel heterogeneous supercomputer "Piz Daint". The solution architecture is based on the Application-as-a-Service concept in order to provide the interested external researchers the regular access to the noise source maps. The solution architecture includes the following sub-systems: (1) data acquisition responsible for

  12. Seismic Source Parameters of Normal-Faulting Inslab Earthquakes in Central Mexico

    Science.gov (United States)

    Rodríguez-Pérez, Quetzalcoatl; Singh, Shri Krishna

    2016-08-01

    We studied 62 normal-faulting inslab earthquakes in the Mexican subduction zone with magnitudes in the range of 3.6 ≤ M w ≤ 7.3 and hypocentral depths of 30 ≤ Z ≤ 108 km. We used different methods to estimate source parameters to observe differences in stress drop, corner frequencies, source dimensions, source duration, energy-to-moment ratio, radiated efficiency, and radiated seismic energy. The behavior of these parameters is derived. We found that normal-faulting inslab events have higher radiated seismic energy, energy-to-moment ratio, and stress drop than interplate earthquakes as expected. This may be explained by the mechanism dependence of radiated seismic energy and apparent stress reported in previous source parameter studies. The energy-to-moment ratio data showed large scatter and no trend with seismic moment. The stress drop showed no trend with seismic moment, but an increment with depth. The radiated seismic efficiencies showed similar values to those obtained from interplate events, but higher than near-trench events. We found that the source duration is independent of the depth. We also derived source scaling relationships for the mentioned parameters. The low level of uncertainties for the seismic source parameters and scaling relationships showed that the obtained parameters are robust. Therefore, reliable source parameter estimation can be carried out using the obtained scaling relationships. We also studied regional stress field of normal-faulting inslab events. Heterogeneity exists in the regional stress field, as indicated by individual stress tensor inversions conducted for two different depth intervals ( Z 40 km, respectively). While the maximum stress axis ( σ 1) appears to be consistent and stable, the orientations of the intermediate and minimum stresses ( σ 2 and σ 3) vary over the depth intervals. The stress inversion results showed that the tensional axes are parallel to the dip direction of the subducted plate. At depths

  13. Geothermal induced seismicity: What links source mechanics and event magnitudes to faulting regime and injection rates?

    Science.gov (United States)

    Martinez-Garzon, Patricia; Kwiatek, Grzegorz; Bohnhoff, Marco; Dresen, Georg

    2017-04-01

    Improving estimates of seismic hazard associated to reservoir stimulation requires advanced understanding of the physical processes governing induced seismicity, which can be better achieved by carefully processing large datasets. To this end, we investigate source-type processes (shear/tensile/compaction) and rupture geometries with respect to the local stress field using seismicity from The Geysers (TG) and Salton Sea geothermal reservoirs, California. Analysis of 869 well-constrained full moment tensors (MW 0.8-3.5) at TG reveals significant non-double-couple (NDC) components (>25%) for 65% of the events and remarkably diversity in the faulting mechanisms. Volumetric deformation is clearly governed by injection rates with larger NDC components observed near injection wells and during high injection periods. The overall volumetric deformation from the moment tensors increases with time, possibly reflecting a reservoir pore pressure increase after several years of fluid injection with no significant production nearby. The obtained source mechanisms and fault orientations are magnitude-dependent and vary significantly between faulting regimes. Normal faulting events (MW dilatancy, and they occur on varying fault orientations. In contrast, strike-slip events dominantly reveal a double-couple source, larger magnitudes (MW > 2) and mostly occur on optimally oriented faults with respect to the local stress field. NDC components indicating closure of cracks and pore spaces in the source region are found for reverse faulting events with MW > 2.5. Our findings from TG are generally consistent with preliminary source-type results from a reduced subset of well-recorded seismicity at the Salton Sea geothermal reservoir. Combined results imply that source processes and magnitudes of geothermal-induced seismicity are strongly affected by and systematically related to the hydraulic operations and the local stress state.

  14. Linearized versus non-linear inverse methods for seismic localization of underground sources

    DEFF Research Database (Denmark)

    Oh, Geok Lian; Jacobsen, Finn

    2013-01-01

    The problem of localization of underground sources from seismic measurements detected by several geophones located on the ground surface is addressed. Two main approaches to the solution of the problem are considered: a beamforming approach that is derived from the linearized inversion problem, a...

  15. Seismicity at Old Faithful Geyser: an isolated source of geothermal noise and possible analogue of volcanic seismicity

    Science.gov (United States)

    Kieffer, S.W.

    1984-01-01

    Old Faithful Geyser in Yellowstone National Park, U.S.A., is a relatively isolated source of seismic noise and exhibits seismic behavior similar to that observed at many volcanoes, including "bubblequakes" that resemble B-type "earthquakes", harmonic tremor before and during eruptions, and periods of seismic quiet prior to eruptions. Although Old Faithful differs from volcanoes in that the conduit is continuously open, that rock-fracturing is not a process responsible for seismicity, and that the erupting fluid is inviscid H2O rather than viscous magma, there are also remarkable similarities in the problems of heat and mass recharge to the system, in the eruption dynamics, and in the seismicity. Water rises irregularly into the immediate reservoir of Old Faithful as recharge occurs, a fact that suggests that there are two enlarged storage regions: one between 18 and 22 m (the base of the immediate reservoir) and one between about 10 and 12 m depth. Transport of heat from hot water or steam entering at the base of the recharging water column into cooler overlying water occurs by migration of steam bubbles upward and their collapse in the cooler water, and by episodes of convective overturn. An eruption occurs when the temperature of the near-surface water exceeds the boiling point if the entire water column is sufficiently close to the boiling curve that the propagation of pressure-release waves (rarefactions) down the column can bring the liquid water onto the boiling curve. The process of conversion of the liquid water in the conduit at the onset of an eruption into a two-phase liquid-vapor mixture takes on the order of 30 s. The seismicity is directly related to the sequence of filling and heating during the recharge cycle, and to the fluid mechanics of the eruption. Short (0.2-0.3 s), monochromatic, high-frequency events (20-60 Hz) resembling unsustained harmonic tremor and, in some instances, B-type volcanic earthquakes, occur when exploding or imploding

  16. Automated classification of seismic sources in a large database: a comparison of Random Forests and Deep Neural Networks.

    Science.gov (United States)

    Hibert, Clement; Stumpf, André; Provost, Floriane; Malet, Jean-Philippe

    2017-04-01

    In the past decades, the increasing quality of seismic sensors and capability to transfer remotely large quantity of data led to a fast densification of local, regional and global seismic networks for near real-time monitoring of crustal and surface processes. This technological advance permits the use of seismology to document geological and natural/anthropogenic processes (volcanoes, ice-calving, landslides, snow and rock avalanches, geothermal fields), but also led to an ever-growing quantity of seismic data. This wealth of seismic data makes the construction of complete seismicity catalogs, which include earthquakes but also other sources of seismic waves, more challenging and very time-consuming as this critical pre-processing stage is classically done by human operators and because hundreds of thousands of seismic signals have to be processed. To overcome this issue, the development of automatic methods for the processing of continuous seismic data appears to be a necessity. The classification algorithm should satisfy the need of a method that is robust, precise and versatile enough to be deployed to monitor the seismicity in very different contexts. In this study, we evaluate the ability of machine learning algorithms for the analysis of seismic sources at the Piton de la Fournaise volcano being Random Forest and Deep Neural Network classifiers. We gather a catalog of more than 20,000 events, belonging to 8 classes of seismic sources. We define 60 attributes, based on the waveform, the frequency content and the polarization of the seismic waves, to parameterize the seismic signals recorded. We show that both algorithms provide similar positive classification rates, with values exceeding 90% of the events. When trained with a sufficient number of events, the rate of positive identification can reach 99%. These very high rates of positive identification open the perspective of an operational implementation of these algorithms for near-real time monitoring of

  17. Seismo-volcano source localization with triaxial broad-band seismic array

    Science.gov (United States)

    Inza, L. A.; Mars, J. I.; Métaxian, J. P.; O'Brien, G. S.; Macedo, O.

    2011-10-01

    Seismo-volcano source localization is essential to improve our understanding of eruptive dynamics and of magmatic systems. The lack of clear seismic wave phases prohibits the use of classical location methods. Seismic antennas composed of one-component (1C) seismometers provide a good estimate of the backazimuth of the wavefield. The depth estimation, on the other hand, is difficult or impossible to determine. As in classical seismology, the use of three-component (3C) seismometers is now common in volcano studies. To determine the source location parameters (backazimuth and depth), we extend the 1C seismic antenna approach to 3Cs. This paper discusses a high-resolution location method using a 3C array survey (3C-MUSIC algorithm) with data from two seismic antennas installed on an andesitic volcano in Peru (Ubinas volcano). One of the main scientific questions related to the eruptive process of Ubinas volcano is the relationship between the magmatic explosions and long-period (LP) swarms. After introducing the 3C array theory, we evaluate the robustness of the location method on a full wavefield 3-D synthetic data set generated using a digital elevation model of Ubinas volcano and an homogeneous velocity model. Results show that the backazimuth determined using the 3C array has a smaller error than a 1C array. Only the 3C method allows the recovery of the source depths. Finally, we applied the 3C approach to two seismic events recorded in 2009. Crossing the estimated backazimuth and incidence angles, we find sources located 1000 ± 660 m and 3000 ± 730 m below the bottom of the active crater for the explosion and the LP event, respectively. Therefore, extending 1C arrays to 3C arrays in volcano monitoring allows a more accurate determination of the source epicentre and now an estimate for the depth.

  18. A Vibroseis Seismic Source for Climate, Ice Sheet and Tectonic Studies in Antarctica

    Science.gov (United States)

    Speece, M. A.; Luyendyk, B. P.; Powell, R. D.; Wilson, D. S.; Pekar, S. F.; Harwood, D. M.; Tulaczyk, S. M.

    2012-12-01

    Seismology's role in Antarctica is to help determine the geology of the subsurface of this still largely unexplored continent. Seismic reflection surveys in Antarctica have traditionally been collected as marine multichannel and single channel data. However, controlled or active source seismic experiments have played an integral, albeit limited, part in geophysical surveys of the Antarctic ice sheet. In more recent years, sea-ice and ice-shelf seismic reflection surveys have shown promise for producing useful data for regions not accessible by ship. Unfortunately a thick firn layer that covers much of the Antarctica ice sheet has limited the use of surface-based active seismic sources. To overcome attenuation caused by the firn layer, explosives are typically placed in 10 to 30 m-deep boreholes. These shot holes can be drilled by a variety of techniques but all require significant time and energy. In contrast to an impulsive seismic source that releases energy over about a millisecond duration, a seismic vibrator (vibroseis) emits energy as a controlled sweep of frequencies over several seconds. As a consequence, energy losses due to inelastic processes are less because of reduced ground pressure and the total energy produced is integrated over the length of the sweep. Long seismic reflection profiles across Antarctica could be accomplished efficiently by using a vibroseis that in turn pulls a snow streamer. We propose the acquisition of a vibroseis for Antarctic research by scientists within the U.S. Antarctic Program (USAP). Antarctic research objectives that could be impacted by the use of a seismic vibrator include (1) mapping of sub-ice stratigraphic sequences suitable for sampling by scientific drilling, (2) correlating offshore and onshore seismic data and complementing airborne geophysical surveys to help determine Antarctica's geologic history, (3) identifying ice-bedrock interface properties and exploring grounding-line processes, (4) exploring sub

  19. Velocity Model Using the Large-N Seismic Array from the Source Physics Experiment (SPE)

    Science.gov (United States)

    Chen, T.; Snelson, C. M.

    2016-12-01

    The Source Physics Experiment (SPE) is a multi-institutional, multi-disciplinary project that consists of a series of chemical explosions conducted at the Nevada National Security Site (NNSS). The goal of SPE is to understand the complicated effect of geological structures on seismic wave propagation and source energy partitioning, develop and validate physics-based modeling, and ultimately better monitor low-yield nuclear explosions. A Large-N seismic array was deployed at the SPE site to image the full 3D wavefield from the most recent SPE-5 explosion on April 26, 2016. The Large-N seismic array consists of 996 geophones (half three-component and half vertical-component sensors), and operated for one month, recording the SPE-5 shot, ambient noise, and additional controlled-sources (a large hammer). This study uses Large-N array recordings of the SPE-5 chemical explosion to develop high resolution images of local geologic structures. We analyze different phases of recorded seismic data and construct a velocity model based on arrival times. The results of this study will be incorporated into the large modeling and simulation efforts as ground-truth further validating the models.

  20. Location of the Carlsberg Fault zone from seismic controlled-source fan recordings

    Science.gov (United States)

    Nielsen, Lars; Thybo, Hans

    2004-04-01

    We locate the concealed Carlsberg Fault zone in the city of Copenhagen from seismic fan recordings. The fault is part of a fault system close to the border between the Danish Basin and the Baltic Shield. Recent earthquakes indicate that this area is tectonically active. The fault zone is a seismic low-velocity zone. Fan shots were recorded on three receiver arrays (1.5-2.4 km long arcs) across the fault. Sources were placed inside and up to ~500 m away from the ~400-700 m wide fault zone at offsets of up to ~7 km. Shots inside the fault zone show: 1) weak, delayed first arrivals inside the fault zone; 2) stronger first arrivals outside the fault zone; 3) guided waves inside the fault zone. The fault is a shadow zone for shots detonated outside the fault zone. Our approach facilitates fault mapping in densely urbanized areas where seismic profiling is not feasible.

  1. Seismic hazard in Romania associated to Vrancea subcrustal source Deterministic evaluation

    CERN Document Server

    Radulian, M; Moldoveanu, C L; Panza, G F; Vaccari, F

    2002-01-01

    Our study presents an application of the deterministic approach to the particular case of Vrancea intermediate-depth earthquakes to show how efficient the numerical synthesis is in predicting realistic ground motion, and how some striking peculiarities of the observed intensity maps are properly reproduced. The deterministic approach proposed by Costa et al. (1993) is particularly useful to compute seismic hazard in Romania, where the most destructive effects are caused by the intermediate-depth earthquakes generated in the Vrancea region. Vrancea is unique among the seismic sources of the World because of its striking peculiarities: the extreme concentration of seismicity with a remarkable invariance of the foci distribution, the unusually high rate of strong shocks (an average frequency of 3 events with magnitude greater than 7 per century) inside an exceptionally narrow focal volume, the predominance of a reverse faulting mechanism with the T-axis almost vertical and the P-axis almost horizontal and the mo...

  2. On the use of a laser ablation as a laboratory seismic source

    Science.gov (United States)

    Shen, Chengyi; Brito, Daniel; Diaz, Julien; Zhang, Deyuan; Poydenot, Valier; Bordes, Clarisse; Garambois, Stéphane

    2017-04-01

    Mimic near-surface seismic imaging conducted in well-controlled laboratory conditions is potentially a powerful tool to study large scale wave propagations in geological media by means of upscaling. Laboratory measurements are indeed particularly suited for tests of theoretical modellings and comparisons with numerical approaches. We have developed an automated Laser Doppler Vibrometer (LDV) platform, which is able to detect and register broadband nano-scale displacements on the surface of various materials. This laboratory equipment has already been validated in experiments where piezoelectric transducers were used as seismic sources. We are currently exploring a new seismic source in our experiments, a laser ablation, in order to compensate some drawbacks encountered with piezoelectric sources. The laser ablation source is considered to be an interesting ultrasound wave generator since the 1960s. It was believed to have numerous potential applications such as the Non-Destructive Testing (NDT) and the measurements of velocities and attenuations in solid samples. We aim at adapting and developing this technique into geophysical experimental investigations in order to produce and explore complete micro-seismic data sets in the laboratory. We will first present the laser characteristics including its mechanism, stability, reproducibility, and will evaluate in particular the directivity patterns of such a seismic source. We have started by applying the laser ablation source on the surfaces of multi-scale homogeneous aluminum samples and are now testing it on heterogeneous and fractured limestone cores. Some other results of data processing will also be shown, especially the 2D-slice V P and V S tomographic images obtained in limestone samples. Apart from the experimental records, numerical simulations will be carried out for both the laser source modelling and the wave propagation in different media. First attempts will be done to compare quantitatively the

  3. Estimation of earthquake source parameters in the Kachchh seismic ...

    Indian Academy of Sciences (India)

    Durgada Nagamani

    2017-07-25

    Jul 25, 2017 ... Earthquake source parameters and crustal Q0 values for the 138 selected local events of (Mw:2.5−4.4) the 2001 Bhuj earthquake sequence have been computed through inversion modelling of S-waves from three-component broadband seismometer data. SEISAN software has been used to locate the ...

  4. Seismic sources near Jang Bogo Station, Terra Nova Bay, East Antarctica

    Science.gov (United States)

    Kong, C.; Kang, T. S.

    2016-12-01

    The Jang Bogo Research Station is the second Korean Antarctic base which was build in Terra Nova Bay, Victoria Land, in the southeastern part of Antarctica in 2014. For the purpose of monitoring various natural seismic signals as well as local earthquakes in and around the station, two broadband seismographs were installed within the station compound and were operated during the second overwintering period from December 2014 to November 2015. Seismic data were continuously recorded during the period, and thus they might deliver much of information on the natural and artificial phenomena in the vicinity of the station. From both the temporal and spectral analyses, it was revealed that the continuous data are consisted of various types of event waveforms which are strongly correlated with variety of seismic sources. Event waveforms are classified into major four categories in accordance with their origin: tectonic earthquakes, volcanic earthquakes, cryogenic events such as icequakes, and atmospheric perturbation. Besides typical waveforms from local and teleseismic earthquakes, local volcano-related signals are expected. A prime source of those signals is Mt. Melbourne which is the only active volcano on the Antarctic mainland and is located in about 30 km northeast of the Jang Bogo station. While no magma eruption occurred during the overwinter period, phreatic eruptions of gases at the summit of Mt. Melbourne were observed sporadically. Seismic sources of the ice-related signal are associated with the Campbell glacier which is originated from the end of Mesa Range in Victoria Land. The Campbell glacier flows into Terra Nova Bay in Ross Sea and forms Campbell ice tongue that is a seaward extension of the glacier. The fast-flowing movement of the glacier appears to generate seismic signals observed at the station. Sometimes katabatic winds, which are downslope winds transiently blowing from Mt. Browning during the Antarctic winter period, massaged the ground and thus

  5. Quantification of source uncertainties in Seismic Probabilistic Tsunami Hazard Analysis (SPTHA)

    Science.gov (United States)

    Selva, J.; Tonini, R.; Molinari, I.; Tiberti, M. M.; Romano, F.; Grezio, A.; Melini, D.; Piatanesi, A.; Basili, R.; Lorito, S.

    2016-06-01

    We propose a procedure for uncertainty quantification in Probabilistic Tsunami Hazard Analysis (PTHA), with a special emphasis on the uncertainty related to statistical modelling of the earthquake source in Seismic PTHA (SPTHA), and on the separate treatment of subduction and crustal earthquakes (treated as background seismicity). An event tree approach and ensemble modelling are used in spite of more classical approaches, such as the hazard integral and the logic tree. This procedure consists of four steps: (1) exploration of aleatory uncertainty through an event tree, with alternative implementations for exploring epistemic uncertainty; (2) numerical computation of tsunami generation and propagation up to a given offshore isobath; (3) (optional) site-specific quantification of inundation; (4) simultaneous quantification of aleatory and epistemic uncertainty through ensemble modelling. The proposed procedure is general and independent of the kind of tsunami source considered; however, we implement step 1, the event tree, specifically for SPTHA, focusing on seismic source uncertainty. To exemplify the procedure, we develop a case study considering seismic sources in the Ionian Sea (central-eastern Mediterranean Sea), using the coasts of Southern Italy as a target zone. The results show that an efficient and complete quantification of all the uncertainties is feasible even when treating a large number of potential sources and a large set of alternative model formulations. We also find that (i) treating separately subduction and background (crustal) earthquakes allows for optimal use of available information and for avoiding significant biases; (ii) both subduction interface and crustal faults contribute to the SPTHA, with different proportions that depend on source-target position and tsunami intensity; (iii) the proposed framework allows sensitivity and deaggregation analyses, demonstrating the applicability of the method for operational assessments.

  6. Large seismic source imaging from old analogue seismograms

    Science.gov (United States)

    Caldeira, Bento; Buforn, Elisa; Borges, José; Bezzeghoud, Mourad

    2017-04-01

    In this work we present a procedure to recover the ground motions by a proper digital structure, from old seismograms in analogue physical support (paper or microfilm) to study the source rupture process, by application of modern finite source inversion tools. Despite the quality that the analog data and the digitizing technologies available may have, recover the ground motions with the accurate metrics from old seismograms, is often an intricate procedure. Frequently the general parameters of the analogue instruments response that allow recover the shape of the ground motions (free periods and damping) are known, but the magnification that allow recover the metric of these motions is dubious. It is in these situations that the procedure applies. The procedure is based on assign of the moment magnitude value to the integral of the apparent Source Time Function (STF), estimated by deconvolution of a synthetic elementary seismogram from the related observed seismogram, corrected with an instrument response affected by improper magnification. Two delicate issues in the process are 1) the calculus of the synthetic elementary seismograms that must consider later phases if applied to large earthquakes (the portions of signal should be 3 or 4 times larger than the rupture time) and 2) the deconvolution to calculate the apparent STF. In present version of the procedure was used the Direct Solution Method to compute the elementary seismograms and the deconvolution was processed in time domain by an iterative algorithm that allow constrains the STF to stay positive and time limited. The method was examined using synthetic data to test the accuracy and robustness. Finally, a set of 17 real old analog seismograms from the Santa Maria (Azores) 1939 earthquake (Mw=7.1) was used in order to recover the waveforms in the required digital structure, from which by inversion allows compute the finite source rupture model (slip distribution). Acknowledgements: This work is co

  7. Determination of Seismic Source Depths from Differential Travel Times

    Science.gov (United States)

    1975-06-30

    MLm »Ei »• TT^C OF Btro*)* • »IMtOD COVCAfD £ Final Report N/A F08606-75-C-002S 13 •’•’JC»*«* fk tMfMT.faojCCT. T*m 1> HCFORT CAT...Identifica- tion of the depth phase is verified when the variations in the differential travel times are in agreement with the differential travel...when the variations in the differential travel times are in agreement with the differential travel time tables for the given source to station

  8. Development of a downhole seismic source with controlled waveform; Hakei seigyogata kochu shingen no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Kuroda, T.; Ikawa, T. [Japex Jeoscience Institute, Tokyo (Japan); Sato, T. [Meiho Engineering Co. Ltd., Tokyo (Japan); Kakuma, H. [Akashi Corp., Tokyo (Japan); Onuma, H. [Engineering Advancement Association of Japan, Tokyo (Japan)

    1997-05-27

    A downhole seismic source which can output continuous waves having arbitrary waveforms was developed. The development was targeted to make tomographic exploration purposed to evaluate geological properties of a ground bed before and after constructing a building in a ground several hundred meters deep from the ground surface. The source is considered to be used in an environment consisting of soft rocks or more robust rocks and having no casing. It can be used in a well hole having a diameter of 100 mm, is capable of measuring P and S waves in a distance between well holes of up to 100 m, can be used at a depth of up to 500 m, and can output waveforms having seismic source spectra of up to 1000 Hz. An oscillation actuator using laminated piezo-electric elements was used for the oscillation element. The seismic source consists of a hydraulic device to clamp the equipment onto hole walls, piezo-electric elements as the oscillation element, and an inertia weight for applying vibration from above and below. To make an oscillation, the main body is first clamped on the hole wall. For horizontal oscillation, the piezo-electric elements contained in a clamping device provide the horizontal oscillation. For vertical oscillation, the piezo-electric elements placed below the main body oscillates the inertia weight. The initially targeted specifications have been achieved. 3 refs., 4 figs., 1 tab.

  9. Retrieving Source-Time Function and Seismic Moment Tensor From Near Field Records

    Science.gov (United States)

    Morales, Catalina; Ruiz, Javier A.; Ortega, Francisco; Rivera, Luis

    2017-04-01

    Retrieve earthquake source parameters from seismological or geodetic data is an important aspect in the rapid characterization of the earthquake source, which is particularly relevant in real-time operations. The inversion of seismic moment tensors and slip distributions of large earthquakes is a recurrent and important topic in seismology because it allows to know the source properties and rupture process. Several methodologies allow to make these inferences assuming different levels of complexity of the earthquake source, for instance, the Global Centroid Moment Tensor compute routinely the centroid moment tensor from global seismic data, on the other hand, agencies such as the National Earthquake Information Center have implemented methodologies to retrieve the moment tensor in real-time (e.g the W-Phase). However, the joint inversion of the moment tensor and the source-time function using regional and near-field data is a promising approach to characterize source parameters. Several methodologies allow to invert the seismic moment tensor using broadband regional data assuming a simple source-time function (e.g. impulsive, or with a triangular shape), but are usually limited because broadband stations get saturated near the source for moderate and large earthquakes. Yagi and Nishimura (2011) proposed a method that inverts the moment tensor and the half duration using strong motion data. Weber (2009) computes the seismic moment tensor as a function of time using broadband regional data, applying a inverse method that minimize the L1-norm, and then retrieves the source-time function. The aim of this study is to develop a method and a computational tool that allows to jointly invert the moment tensor and the source-time function using strong motion and broadband regional data. The inverse method is applied in two steps, (1) we invert the moment tensor assuming a triangular source-time function and, (2) minimizing the L2-norm, we invert the amplitude of a series of

  10. Regional Seismic Identification Research:Processing, Transportability and Source Models

    Energy Technology Data Exchange (ETDEWEB)

    Walter, W; Mayeda, K; Rodgers, A; Taylor, S; Dodge, D; Matzel, E; Ganzberger, M

    2004-07-09

    Our identification research for the past several years has focused on the problem of correctly discriminating small-magnitude explosions from a background of earthquakes, mining tremors, and other events. Small magnitudes lead to an emphasis on regional waveforms. It has been shown that at each test site where earthquake and explosions are in close proximity and recorded at the same station, clear differences in the regional body waves such as the relative high frequency amplitudes of P and S waves can be used to discriminate between event types. However path and source effects can also induce such differences, therefore these must be quantified and accounted for. We have been using a specific technique called Magnitude and Distance Amplitude Correction (MDAC), with some success to account for some of these effects.

  11. Continuous active-source seismic monitoring of CO2 injection in abrine aquifer

    Energy Technology Data Exchange (ETDEWEB)

    Daley, Thomas M.; Solbau, Ray D.; Ajo-Franklin, Jonathan B.; Benson, Sally M.

    2006-12-10

    Continuous crosswell seismic monitoring of a small-scale CO2injection was accomplished with the development of a noveltubing-deployed piezoelectric borehole source. This piezotube source wasdeployed on the CO2 injection tubing, near the top of the saline aquiferreservoir at 1657-m depth, and allowed acquisition of crosswellrecordings at 15-minute intervals during the multiday injection. Thechange in traveltime recorded at various depths in a nearby observationwell allowed hour-by-hour monitoring of the growing CO2 plume via theinduced seismic velocity change. Traveltime changes of 0.2 to 1.0 ms ( upto 8 percent ) were observed, with no change seen at control sensorsplaced above the reservoir. The traveltime measurements indicate that theCO2 plume reached the top of the reservoir sand before reaching theobservation well, where regular fluid sampling was occuring during theinjection, thus providing information about the in situ buoyancy ofCO2.

  12. Vector-Sensor MUSIC for Polarized Seismic Sources Localization

    Directory of Open Access Journals (Sweden)

    Jérôme I. Mars

    2005-01-01

    Full Text Available This paper addresses the problem of high-resolution polarized source detection and introduces a new eigenstructure-based algorithm that yields direction of arrival (DOA and polarization estimates using a vector-sensor (or multicomponent-sensor array. This method is based on separation of the observation space into signal and noise subspaces using fourth-order tensor decomposition. In geophysics, in particular for reservoir acquisition and monitoring, a set of Nx-multicomponent sensors is laid on the ground with constant distance Δx between them. Such a data acquisition scheme has intrinsically three modes: time, distance, and components. The proposed method needs multilinear algebra in order to preserve data structure and avoid reorganization. The data is thus stored in tridimensional arrays rather than matrices. Higher-order eigenvalue decomposition (HOEVD for fourth-order tensors is considered to achieve subspaces estimation and to compute the eigenelements. We propose a tensorial version of the MUSIC algorithm for a vector-sensor array allowing a joint estimation of DOA and signal polarization estimation. Performances of the proposed algorithm are evaluated.

  13. Effects of vibratory pile driver noise on echolocation and vigilance in bottlenose dolphins (Tursiops truncatus).

    Science.gov (United States)

    Branstetter, Brian K; Bowman, Victoria F; Houser, Dorian S; Tormey, Megan; Banks, Patchouly; Finneran, James J; Jenkins, Keith

    2018-01-01

    Vibratory pile drivers, used for marine construction, can produce sustained, high sound pressure levels (SPLs) in areas that overlap with dolphin habitats. Dolphins rely on echolocation for navigation, detecting predators and prey, and to coordinate group behavior. This study examined the effects of vibratory pile driver noise on dolphin sustained target detection capabilities through echolocation. Five dolphins were required to scan their enclosure and indicate the occurrences of phantom echoes during five different source levels of vibratory pile driver playback sound (no-playback control, 110, 120, 130, and 140 dB re 1 μPa). Three of the dolphins demonstrated a significant decrease in target detection performance at 140 dB playback level that was associated with an almost complete secession of echolocation activity. The performance of two dolphins was not affected. All dolphins rapidly returned to baseline levels of target detection performance by their second replication. However, an increased number of clicks was produced at the highest playback SPL. The data suggest that the decrease in vigilant behavior was due to the vibratory pile driver noise distracting the dolphins and decreasing their motivation to perform the task.

  14. R and D -- Seismic report on the influence of the source region on regional seismic waveforms as inferred from modeling

    Energy Technology Data Exchange (ETDEWEB)

    App, F.N.; Jones, E.M.; Bos, R.J.

    1997-11-01

    The identification of an underground nuclear test from its seismic signal recorded by seismometers at regional distances is one of the fundamental scientific goals of the Comprehensive Test Ban Treaty R and D Program. The work being reported here addresses the issue of event discrimination through the use of computer models that use realistic simulations of nuclear explosions in various settings for the generation of near-regional and regional synthetic seismograms. The study exercises some unique, recently developed computer modeling capabilities that heretofore have not been available for discrimination studies. A variety of source conditions and regional paths are investigated. Under the assumptions of the study, conclusions are: (1) spall, non-linear deformation, and depth-of-burial do not substantially influence the near-regional signal and (2) effects due to basins along the regional path very much dominate over source region geology in influencing the signal at regional distances. These conclusions, however, are relevant only for the frequencies addressed, which span the range from 0.1 to 1 Hz for the regional calculations and 0.1 to 3 Hz for the near-regional calculations. They also are relevant only for the crudely ``China-like`` basin, crust, and mantle properties used in the study. If it is determined that further investigations are required, researchers may use this study as a template for such work.

  15. Mapping the sources of the seismic wave field at Kilauea volcano, Hawaii, using data recorded on multiple seismic Antennas

    Science.gov (United States)

    Almendros, J.; Chouet, B.; Dawson, P.; Huber, Caleb G.

    2002-01-01

    Seismic antennas constitute a powerful tool for the analysis of complex wave fields. Well-designed antennas can identify and separate components of a complex wave field based on their distinct propagation properties. The combination of several antennas provides the basis for a more complete understanding of volcanic wave fields, including an estimate of the location of each individual wave-field component identified simultaneously by at least two antennas. We used frequency-slowness analyses of data from three antennas to identify and locate the different components contributing to the wave fields recorded at Kilauea volcano, Hawaii, in February 1997. The wave-field components identified are (1) a sustained background volcanic tremor in the form of body waves generated in a shallow hydrothermal system located below the northeastern edge of the Halemaumau pit crater; (2) surface waves generated along the path between this hydrothermal source and the antennas; (3) back-scattered surface wave energy from a shallow reflector located near the southeastern rim of Kilauea caldera; (4) evidence for diffracted wave components originating at the southeastern edge of Halemaumau; and (5) body waves reflecting the activation of a deeper tremor source between 02 hr 00 min and 16 hr 00 min Hawaii Standard Time on 11 February.

  16. Induced Seismicity from different sources in Italy: how to interpret it?

    Science.gov (United States)

    Pastori, M.; De Gori, P.; Piccinini, D.; Bagh, S.; Improta, L.; Chiarabba, C.

    2015-12-01

    Typically the term "induced seismicity" is used to refer minor earthquakes and tremors caused by human activities that alter the stresses and strains on the Earth's crust. In the last years, the interest in the induced seismicity related to fluids (oil and gas, and geothermal resources) extraction or injection is increased, because it is believed to be responsible to enucleate earthquakes. Possible sources of induced seismicity are not only represented by the oil and gas production but also, i.e., by changes in the water level of artificial lakes. The aim of this work is to show results from two different sources, wastewater injection and changes in the water level of an artificial reservoir (Pertusillo lake), that can produce induced earthquakes observed in the Val d'Agri basin (Italy) and to compare them with variation in crustal elastic parameters. Val d'Agri basin in the Apennines extensional belt hosts the largest oilfield in onshore Europe and is bordered by NW-SE ­trending fault systems. Most of the recorded seismicity seems to be related to these structures. We correlated the seismicity rate, injection curves and changes in water levels with temporal variations of Vp/Vs and anisotropic parameters of the crustal reservoirs and in the nearby area. We analysed about 983 high-quality recordings occurred from 2002 to 2014 in Val d'Agri basin from temporary and permanent network held by INGV and ENI corporate. 3D high-precision locations and manual-revised P- and S-picking are used to estimate anisotropic parameters (delay time and fast direction polarization) and Vp/Vs ratio. Seismicity is mainly located in two areas: in the SW of the Pertusillo Lake, and near the Eni Oil field (SW and NE of the Val d'Agri basin respectively). Our correlations well recognize the seismicity diffusion process, caused by both water injection and water level changes; these findings could help to model the active and pre-existing faults failure behaviour.

  17. THE INDIAN OCEAN TSUNAMI OF 26 DECEMBER 2004 Analysis of Seismic Source Mechanism

    Directory of Open Access Journals (Sweden)

    R Mazova

    2012-01-01

    Full Text Available Based on the keyboard model of tsunamigenic earthquakes, an analysis was performed of the physical aspects of the 26 December 2004 earthquake off Sumatra and of the seismic source of the great tsunami generated in the Indian Ocean. A simplified keyboard model with vertical displacements of keyboard blocks was used for the numerical simulation in defining the tsunami’s generation source and, based on known bathymetry, its subsequent propagation across the Indian Ocean basin. The numerical simulation of the seismic source took into account the oblique character of subduction zone, which was characteristic for this particular earthquake. Furthermore, the analysis evaluated the different scenarios of keyboard blocks motions - corresponding to real seismic and hydro acoustic studies of the earthquake process - as reported in the literature. Adequateness of the calculations performed was verified by comparison of real altimetry records of satellite “Yason-1” with virtual altimetric record, obtained by us for each calculation. The computational analysis helped explain the complex character of the tsunami and of its propagation and energy flux distribution in the Indian Ocean basin.

  18. Non double couple seismic sources, faults interaction and hypothesis of self-organized criticality

    Directory of Open Access Journals (Sweden)

    S. Yunga

    2005-01-01

    Full Text Available Non double couple (NDC sources are considered in framework of the hypothesis that the process of seismic rupture can be viewed as a result of complicated fault geometry and its segmentation. Analytical approach is found to reveal reliability of NDC measure taking into consideration the values of seismic moment tensor errors. The study focuses on the comparison of the deformation modes of the NDC sources with the stress states in its vicinity. The deformation modes of faulting and fracturing at a small scale in NDC earthquake focus and at regional scale in geological unit were investigated using at the last case summation of seismic moment tensors. These local and regional deformation modes in some of geodynamic regimes confirm the self-similarity assumption. For the whole data set scaling relations seem to be more complicated. This feature implies that besides stresses second order factors, as the hydrothermal or magmatic pore fluids in rock, influence source characteristics and bring new complications in scaling relations.

  19. Seismic Consequence Abstraction

    Energy Technology Data Exchange (ETDEWEB)

    M. Gross

    2004-10-25

    The primary purpose of this model report is to develop abstractions for the response of engineered barrier system (EBS) components to seismic hazards at a geologic repository at Yucca Mountain, Nevada, and to define the methodology for using these abstractions in a seismic scenario class for the Total System Performance Assessment - License Application (TSPA-LA). A secondary purpose of this model report is to provide information for criticality studies related to seismic hazards. The seismic hazards addressed herein are vibratory ground motion, fault displacement, and rockfall due to ground motion. The EBS components are the drip shield, the waste package, and the fuel cladding. The requirements for development of the abstractions and the associated algorithms for the seismic scenario class are defined in ''Technical Work Plan For: Regulatory Integration Modeling of Drift Degradation, Waste Package and Drip Shield Vibratory Motion and Seismic Consequences'' (BSC 2004 [DIRS 171520]). The development of these abstractions will provide a more complete representation of flow into and transport from the EBS under disruptive events. The results from this development will also address portions of integrated subissue ENG2, Mechanical Disruption of Engineered Barriers, including the acceptance criteria for this subissue defined in Section 2.2.1.3.2.3 of the ''Yucca Mountain Review Plan, Final Report'' (NRC 2003 [DIRS 163274]).

  20. Central and Eastern United States (CEUS) Seismic Source Characterization (SSC) for Nuclear Facilities Project

    Energy Technology Data Exchange (ETDEWEB)

    Kevin J. Coppersmith; Lawrence A. Salomone; Chris W. Fuller; Laura L. Glaser; Kathryn L. Hanson; Ross D. Hartleb; William R. Lettis; Scott C. Lindvall; Stephen M. McDuffie; Robin K. McGuire; Gerry L. Stirewalt; Gabriel R. Toro; Robert R. Youngs; David L. Slayter; Serkan B. Bozkurt; Randolph J. Cumbest; Valentina Montaldo Falero; Roseanne C. Perman' Allison M. Shumway; Frank H. Syms; Martitia (Tish) P. Tuttle

    2012-01-31

    This report describes a new seismic source characterization (SSC) model for the Central and Eastern United States (CEUS). It will replace the Seismic Hazard Methodology for the Central and Eastern United States, EPRI Report NP-4726 (July 1986) and the Seismic Hazard Characterization of 69 Nuclear Plant Sites East of the Rocky Mountains, Lawrence Livermore National Laboratory Model, (Bernreuter et al., 1989). The objective of the CEUS SSC Project is to develop a new seismic source model for the CEUS using a Senior Seismic Hazard Analysis Committee (SSHAC) Level 3 assessment process. The goal of the SSHAC process is to represent the center, body, and range of technically defensible interpretations of the available data, models, and methods. Input to a probabilistic seismic hazard analysis (PSHA) consists of both seismic source characterization and ground motion characterization. These two components are used to calculate probabilistic hazard results (or seismic hazard curves) at a particular site. This report provides a new seismic source model. Results and Findings The product of this report is a regional CEUS SSC model. This model includes consideration of an updated database, full assessment and incorporation of uncertainties, and the range of diverse technical interpretations from the larger technical community. The SSC model will be widely applicable to the entire CEUS, so this project uses a ground motion model that includes generic variations to allow for a range of representative site conditions (deep soil, shallow soil, hard rock). Hazard and sensitivity calculations were conducted at seven test sites representative of different CEUS hazard environments. Challenges and Objectives The regional CEUS SSC model will be of value to readers who are involved in PSHA work, and who wish to use an updated SSC model. This model is based on a comprehensive and traceable process, in accordance with SSHAC guidelines in NUREG/CR-6372, Recommendations for Probabilistic

  1. Utilization of near-source video and ground motion in the assessment of seismic source functions from mining explosions

    Energy Technology Data Exchange (ETDEWEB)

    Stump, B.W. [Los Alamos National Lab., NM (United States); Anderson, D.P. [Southern Methodist Univ., Dallas, TX (United States). Dept. of Geological Sciences

    1995-04-01

    Constraint of the operative physical processes in the source region of mining explosions and the linkage to the generation of seismic waveforms provides the opportunity for controlling ground motion. Development of these physical models can also be used in conjunction with the ground motion data as diagnostics of blasting efficiency. In order to properly address the multi-dimensional aspect of data sets designed to constrain these sources, we are investigating a number of modem visualization tools that have only recently become available with new, high-speed graphical computers that can utilize relatively large data sets. The data sets that are combined in the study of mining explosion sources include near-source ground motion acceleration and velocity records, velocity of detonation measurements in each explosive hole, high speed film, video and shot design information.

  2. New Time-independent and Time-dependent Seismic Source Models for the Calabria Region (Italy) for the Probabilistic Seismic Hazard Maps

    Science.gov (United States)

    Akinci, Aybige; Burrato, Pierfrancesco; Falcone, Giuseppe; Mariucci, Maria Teresa; Murru, Maura; Tiberti, Mara Monica; Vannoli, Paola

    2015-04-01

    The present study is carried out in the framework of the S2-2014 COBAS Project "Constraining Observations into Seismic Hazard" co-funded by the Civil Protection Department of the Presidency of Council of Ministers (DPC) within the general agreement DPC-INGV for the period 2012-2021. The two areas identified as priority areas in the first phase of the activities by the 2012- 2021 Agreement DPC-INGV, namely the Po Plain and the Southern Apennines from Molise-Lazio to Basilicata-Calabria borders, require different strategies for calculating "the best seismic hazard". In this study we develop new time-independent and time-dependent seismic source models for the Calabria region starting from the new version of the DISS (Database of Individual Seismogenic Sources). This version of the Database DISS contains remarkable and notable new data and information on the seismogenic sources and their parameterizations in the Calabria region. The probability of the earthquake occurrences is calculated by developing models of seismicity-derived hazard sources, and models of earthquakes on faults/seismogenic sources. Mainly the four different classes of earthquake source models are developed to be included into the PSHA maps: (1) shallow crustal background seismicity (2) special zone that account for deep background seismicity (many earthquakes deeper than 30 kilometers occur beneath the Calabrian Arc and may have caused considerable damage in the Calabria region; these earthquakes have different ground-motion properties than shallow earthquakes) (3) uniform background source zones (4) finite faults/seismogenic sources as defined in the previous activity. The first three models are based on the earthquake catalog and characterize the hazard from earthquakes Mw>4.7. In most cases, the faults contribute most to the hazard for earthquakes larger than Mw5.5. The earthquake occurrence for the faults are modeled both as a Poisson time-independent process and introducing the various renewal

  3. Accurate estimation of seismic source parameters of induced seismicity by a combined approach of generalized inversion and genetic algorithm: Application to The Geysers geothermal area, California

    Science.gov (United States)

    Picozzi, M.; Oth, A.; Parolai, S.; Bindi, D.; De Landro, G.; Amoroso, O.

    2017-05-01

    The accurate determination of stress drop, seismic efficiency, and how source parameters scale with earthquake size is an important issue for seismic hazard assessment of induced seismicity. We propose an improved nonparametric, data-driven strategy suitable for monitoring induced seismicity, which combines the generalized inversion technique together with genetic algorithms. In the first step of the analysis the generalized inversion technique allows for an effective correction of waveforms for attenuation and site contributions. Then, the retrieved source spectra are inverted by a nonlinear sensitivity-driven inversion scheme that allows accurate estimation of source parameters. We therefore investigate the earthquake source characteristics of 633 induced earthquakes (Mw 2-3.8) recorded at The Geysers geothermal field (California) by a dense seismic network (i.e., 32 stations, more than 17.000 velocity records). We find a nonself-similar behavior, empirical source spectra that require an ωγ source model with γ > 2 to be well fit and small radiation efficiency ηSW. All these findings suggest different dynamic rupture processes for smaller and larger earthquakes and that the proportion of high-frequency energy radiation and the amount of energy required to overcome the friction or for the creation of new fractures surface changes with earthquake size. Furthermore, we observe also two distinct families of events with peculiar source parameters that in one case suggests the reactivation of deep structures linked to the regional tectonics, while in the other supports the idea of an important role of steeply dipping faults in the fluid pressure diffusion.

  4. Testing seismic amplitude source location for fast debris-flow detection at Illgraben, Switzerland

    Directory of Open Access Journals (Sweden)

    F. Walter

    2017-06-01

    Full Text Available Heavy precipitation can mobilize tens to hundreds of thousands of cubic meters of sediment in steep Alpine torrents in a short time. The resulting debris flows (mixtures of water, sediment and boulders move downstream with velocities of several meters per second and have a high destruction potential. Warning protocols for affected communities rely on raising awareness about the debris-flow threat, precipitation monitoring and rapid detection methods. The latter, in particular, is a challenge because debris-flow-prone torrents have their catchments in steep and inaccessible terrain, where instrumentation is difficult to install and maintain. Here we test amplitude source location (ASL as a processing scheme for seismic network data for early warning purposes. We use debris-flow and noise seismograms from the Illgraben catchment, Switzerland, a torrent system which produces several debris-flow events per year. Automatic in situ detection is currently based on geophones mounted on concrete check dams and radar stage sensors suspended above the channel. The ASL approach has the advantage that it uses seismometers, which can be installed at more accessible locations where a stable connection to mobile phone networks is available for data communication. Our ASL processing uses time-averaged ground vibration amplitudes to estimate the location of the debris-flow front. Applied to continuous data streams, inversion of the seismic amplitude decay throughout the network is robust and efficient, requires no manual identification of seismic phase arrivals and eliminates the need for a local seismic velocity model. We apply the ASL technique to a small debris-flow event on 19 July 2011, which was captured with a temporary seismic monitoring network. The processing rapidly detects the debris-flow event half an hour before arrival at the outlet of the torrent and several minutes before detection by the in situ alarm system. An analysis of continuous seismic

  5. Testing seismic amplitude source location for fast debris-flow detection at Illgraben, Switzerland

    Science.gov (United States)

    Walter, Fabian; Burtin, Arnaud; McArdell, Brian W.; Hovius, Niels; Weder, Bianca; Turowski, Jens M.

    2017-06-01

    Heavy precipitation can mobilize tens to hundreds of thousands of cubic meters of sediment in steep Alpine torrents in a short time. The resulting debris flows (mixtures of water, sediment and boulders) move downstream with velocities of several meters per second and have a high destruction potential. Warning protocols for affected communities rely on raising awareness about the debris-flow threat, precipitation monitoring and rapid detection methods. The latter, in particular, is a challenge because debris-flow-prone torrents have their catchments in steep and inaccessible terrain, where instrumentation is difficult to install and maintain. Here we test amplitude source location (ASL) as a processing scheme for seismic network data for early warning purposes. We use debris-flow and noise seismograms from the Illgraben catchment, Switzerland, a torrent system which produces several debris-flow events per year. Automatic in situ detection is currently based on geophones mounted on concrete check dams and radar stage sensors suspended above the channel. The ASL approach has the advantage that it uses seismometers, which can be installed at more accessible locations where a stable connection to mobile phone networks is available for data communication. Our ASL processing uses time-averaged ground vibration amplitudes to estimate the location of the debris-flow front. Applied to continuous data streams, inversion of the seismic amplitude decay throughout the network is robust and efficient, requires no manual identification of seismic phase arrivals and eliminates the need for a local seismic velocity model. We apply the ASL technique to a small debris-flow event on 19 July 2011, which was captured with a temporary seismic monitoring network. The processing rapidly detects the debris-flow event half an hour before arrival at the outlet of the torrent and several minutes before detection by the in situ alarm system. An analysis of continuous seismic records furthermore

  6. Seismic interferometry of the Bighorn Mountains: Using virtual source gathers to increase fold in sparse-source, dense-receiver data

    Science.gov (United States)

    Plescia, S. M.; Sheehan, A. F.; Haines, S. S.; Cook, S. W.; Worthington, L. L.

    2016-12-01

    The Bighorn Arch Seismic Experiment (BASE) was a combined active- and passive-source seismic experiment designed to image deep structures including the Moho beneath a basement-involved foreland arch. In summer 2010, over 1800 Texan receivers, with 4.5 Hz vertical component geophones, were deployed at 100-m to 1-km spacing in a region spanning the Bighorn Arch and the adjacent Bighorn and Powder River Basins. Twenty explosive sources were used to create seismic energy during a two-week acquisition period. Teleseismic earthquakes and mine blasts were also recorded during this time period. We utilize both virtual source interferometry and traditional reflection processing to better understand the deep crustal features of the region and the Moho. The large number of receivers, compared to the limited, widely spaced (10 - 30 km) active-source shots, makes the data an ideal candidate for virtual source seismic interferometry to increase fold. Virtual source interferometry results in data representing a geometry where receiver locations act as if they were seismic source positions. A virtual source gather, the product of virtual source interferometry, is produced by the cross correlation of one receiver's recording, the reference trace, with the recordings of all other receivers in a given shot gather. The cross correlation is repeated for all shot gathers and the resulting traces are stacked. This process is repeated until a virtual source gather has been determined for every real receiver location. Virtual source gathers can be processed with a standard reflection seismic processing flow to yield a reflection section. Improper static corrections can be detrimental to effective stacking, and determination of proper statics is often difficult in areas of significant contrast such as between basin and mountain areas. As such, a natural synergy exists between virtual source interferometry and modern industry reflection seismic processing, with its emphasis on detailed

  7. Seismic Interferometry at a Large, Dense Array: Capturing the Wavefield at the Source Physics Experiment

    Science.gov (United States)

    Matzel, E.; Mellors, R. J.; Magana-Zook, S. A.

    2016-12-01

    Seismic interferometry is based on the observation that the Earth's background wavefield includes coherent energy, which can be recovered by observing over long time periods, allowing the incoherent energy to cancel out. The cross correlation of the energy recorded at a pair of stations results in an estimate of the Green's Function (GF) and is equivalent to the record of a simple source located at one of the stations as recorded by the other. This allows high resolution imagery beneath dense seismic networks even in areas of low seismicity. The power of these inter-station techniques increases rapidly as the number of seismometers in a network increases. For large networks the number of correlations computed can run into the millions and this becomes a "big-data" problem where data-management dominates the efficiency of the computations. In this study, we use several methods of seismic interferometry to obtain highly detailed images at the site of the Source Physics Experiment (SPE). The objective of SPE is to obtain a physics-based understanding of how seismic waves are created at and scattered near the source. In 2015, a temporary deployment of 1,000 closely spaced geophones was added to the main network of instruments at the site. We focus on three interferometric techniques: Shot interferometry (SI) uses the SPE shots as rich sources of high frequency, high signal energy. Coda interferometry (CI) isolates the energy from the scattered wavefield of distant earthquakes. Ambient noise correlation (ANC) uses the energy of the ambient background field. In each case, the data recorded at one seismometer are correlated with the data recorded at another to obtain an estimate of the GF between the two. The large network of mixed geophone and broadband instruments at the SPE allows us to calculate over 500,000 GFs, which we use to characterize the site and measure the localized wavefield. This work performed under the auspices of the U.S. Department of Energy by

  8. Micro-seismic Imaging Using a Source Independent Waveform Inversion Method

    KAUST Repository

    Wang, Hanchen

    2016-04-18

    Micro-seismology is attracting more and more attention in the exploration seismology community. The main goal in micro-seismic imaging is to find the source location and the ignition time in order to track the fracture expansion, which will help engineers monitor the reservoirs. Conventional imaging methods work fine in this field but there are many limitations such as manual picking, incorrect migration velocity and low signal to noise ratio (S/N). In traditional surface survey imaging, full waveform inversion (FWI) is widely used. The FWI method updates the velocity model by minimizing the misfit between the observed data and the predicted data. Using FWI to locate and image microseismic events allows for an automatic process (free of picking) that utilizes the full wavefield. Use the FWI technique, and overcomes the difficulties of manual pickings and incorrect velocity model for migration. However, the technique of waveform inversion of micro-seismic events faces its own problems. There is significant nonlinearity due to the unknown source location (space) and function (time). We have developed a source independent FWI of micro-seismic events to simultaneously invert for the source image, source function and velocity model. It is based on convolving reference traces with the observed and modeled data to mitigate the effect of an unknown source ignition time. The adjoint-state method is used to derive the gradient for the source image, source function and velocity updates. To examine the accuracy of the inverted source image and velocity model the extended image for source wavelet in z-axis is extracted. Also the angle gather is calculated to check the applicability of the migration velocity. By inverting for the source image, source wavelet and the velocity model simultaneously, the proposed method produces good estimates of the source location, ignition time and the background velocity in the synthetic experiments with both parts of the Marmousi and the SEG

  9. Imaging spatial and temporal seismic source variations at Sierra Negra Volcano, Galapagos Islands using back-projection methods

    Science.gov (United States)

    Kelly, C. L.; Lawrence, J. F.; Ebinger, C. J.

    2013-12-01

    Imaging spatial and temporal seismic source variations at Sierra Negra Volcano, Galapagos Islands using back-projection methods Cyndi Kelly1, Jesse F. Lawrence1, Cindy Ebinger2 1Stanford University, Department of Geophysics, 397 Panama Mall, Stanford, CA 94305, USA 2University of Rochester, Department of Earth and Environmental Science, 227 Hutchison Hall, Rochester, NY 14627, USA Low-magnitude seismic signals generated by processes that characterize volcanic and hydrothermal systems and their plumbing networks are difficult to observe remotely. Seismic records from these systems tend to be extremely 'noisy', making it difficult to resolve 3D subsurface structures using traditional seismic methods. Easily identifiable high-amplitude bursts within the noise that might be suitable for use with traditional seismic methods (i.e. eruptions) tend to occur relatively infrequently compared to the length of an entire eruptive cycle. Furthermore, while these impulsive events might help constrain the dynamics of a particular eruption, they shed little insight into the mechanisms that occur throughout an entire eruption sequence. It has been shown, however, that the much more abundant low-amplitude seismic 'noise' in these records (i.e. volcanic or geyser 'tremor') actually represents a series of overlapping low-magnitude displacements that can be directly linked to magma, fluid, and volatile movement at depth. This 'noisy' data therefore likely contains valuable information about the processes occurring in the volcanic or hydrothermal system before, during and after eruption events. In this study, we present a new method to comprehensively study how the seismic source distribution of all events - including micro-events - evolves during different phases of the eruption sequence of Sierra Negra Volcano in the Galapagos Islands. We apply a back-projection search algorithm to image sources of seismic 'noise' at Sierra Negra Volcano during a proposed intrusion event. By analyzing

  10. The effect of explosion parameters on seismic source wavelet calculation and its characteristics

    Science.gov (United States)

    Yimin, Wang; Gang, Tian; Luyang, Yu

    2017-10-01

    This paper focuses on the calculation and analysis of the source wavelet produced by explosions in land seismic exploration, in order to reveal the effect of the explosion parameters on the signal features of seismic records. The calculation process consist of three steps, numerical simulation of explosions in rock and soil, plastic-elastic boundary (PEB) pressure curve fitting and application of the spherical source model. Four groups of explosion parameters are considered, including detonation velocity, charge weight, coupling material and geometry coupling. The study shows that the source wavelets of limestone and sandstone lack of energy in the low frequency range, which can be enlarged by applying a high detonation velocity explosive, a large charge weight and water coupling. The main frequency of source wavelet of loess is relatively low, which can be increased by using a low detonation velocity explosive and a small charge weight. The result is consistent with the field observations and can serve as a guide for selecting the explosion parameters.

  11. Geological Identification of Seismic Source at Opak Fault Based on Stratigraphic Sections of the Southern Mountains

    Directory of Open Access Journals (Sweden)

    Hita Pandita

    2016-08-01

    Full Text Available Earthquake is one of the unpredicted natural disasters on our earth. Despite of the absence of high-accuracy method to precisely predict the occurrence of earthquake, numerous studies have been carried out by seismologists to find it. One of the efforts to address the vulnerability of a region to earthquakes is by recognizing the type of rock as the source of the earthquake. Opak Fault is an active fault which was thought to be the source of earthquakes in Yogyakarta and adjacent areas. This study aimed to determine the seismic source types of rocks in Yogyakarta and adjacent areas. The methods were by measuring stratigraphic sections and the layer thickness in the western part of Southern Mountains. Field study was done in 6 (six research sites. Results of stratigraphic measurement indicated the sedimentary rocks in the Southern Mountains was 3.823 km in thick, while the bedrock was more than 1.042 km in thick. Based on the result, the rock types as the seismic source were thought to originate from the continental crust rocks formed of granite and metamorphic complex.

  12. Secondary seismic sources behind amplitude ratios between the first 2016 and 2013 North Korean nuclear tests

    Science.gov (United States)

    Jin, Ping; Xu, Henglei; Wang, Hongchun; Pan, Changzhou; Xu, Xiong; Wang, Xuliang

    2017-10-01

    Amplitude ratios between the first 2016 and 2013 North Korean nuclear tests for different kinds of seismic waves are compared. The observations show the first 2016 test had generated stronger Rayleigh wave with weaker short-period P and Love waves in comparison with the 2013 test. Amplitude ratios for Rayleigh wave exhibit an obvious periodical variation with station azimuths, while similar variation is absent for amplitude ratios of both P wave and Love wave. To explain the observations, secondary seismic sources including the DC component caused by tectonic release and the CLVD component caused by induced rock damage of the explosions are discussed. It is shown that the DC sources of the two tests should have an identical mechanism with DC moment MDC as well as isotropic moment MISO of the first 2016 test being smaller than that of the 2013 test. Under different assumptions for the DC source mechanism, the observed Rayleigh wave amplitude ratios were fitted to search for the explosions' relative strength of CLVD moment MCLVD with respect to MISO, which is measured by the so-called K index. Results obtained show that under any circumstances the relative CLVD strength of the first 2016 test should be smaller than that of the 2013 test, and when the DC source mechanism is assumed to be thrust-faulting, the CLVD components of the two explosions may be both positive and weak, consistent with the general view point that the Korean nuclear tests are overburied without inducing significant surface disturbance.

  13. A novel seismic source detection and location algorithm implemented to improve the construction of seismic Green's functions from ambient noise in mines

    Science.gov (United States)

    Dales, P.; Audet, P.; Olivier, G.

    2016-12-01

    The seismic Green's functions constructed by the cross-correlation of ambient noise can be biased by azimuthal variations in ambient noise energy due to the presence of strong impulsive and other persistent sources that contaminate individual cross-correlation functions. While earthquake seismology has led to many developments in detection and location of impulsive sources, there is little work related to other persistent sources which can greatly retard or even prevent the retrieval of the Green's function from ambient noise cross-correlations. We adapt a popular acoustical location method, referred to as the Steered Response Power Phase Transform (SRP-PHAT), to detect and locate different types of seismic sources. This method is a beamforming-like approach that uses the cross-correlation functions in a maximum likelihood search to locate sources of seismic energy. We demonstrate the effectiveness of this technique by detecting and locating impulsive sources (microseismic events) and other persistent sources (like drilling or ore-crushers) in several active underground mine environments. We also show how this information is used to create a stacking filter that enables us to construct good estimates of the Green's function in the presence of unfavorable noise conditions. In brief, this method is used to evaluate the orientation of each station pair with respect to the energy distribution of the seismic wavefield for short successive time periods, and only time periods that are favorable are used to construct the cross-correlation functions for each station pair. Finally, we show how temporal variations in the estimated Green's function can be used to infer stress conditions in rock mass and guide mining operations.

  14. Imaging Seismic Source Variations Using Back-Projection Methods at El Tatio Geyser Field, Northern Chile

    Science.gov (United States)

    Kelly, C. L.; Lawrence, J. F.

    2014-12-01

    During October 2012, 51 geophones and 6 broadband seismometers were deployed in an ~50x50m region surrounding a periodically erupting columnar geyser in the El Tatio Geyser Field, Chile. The dense array served as the seismic framework for a collaborative project to study the mechanics of complex hydrothermal systems. Contemporaneously, complementary geophysical measurements (including down-hole temperature and pressure, discharge rates, thermal imaging, water chemistry, and video) were also collected. Located on the western flanks of the Andes Mountains at an elevation of 4200m, El Tatio is the third largest geyser field in the world. Its non-pristine condition makes it an ideal location to perform minutely invasive geophysical studies. The El Jefe Geyser was chosen for its easily accessible conduit and extremely periodic eruption cycle (~120s). During approximately 2 weeks of continuous recording, we recorded ~2500 nighttime eruptions which lack cultural noise from tourism. With ample data, we aim to study how the source varies spatially and temporally during each phase of the geyser's eruption cycle. We are developing a new back-projection processing technique to improve source imaging for diffuse signals. Our method was previously applied to the Sierra Negra Volcano system, which also exhibits repeating harmonic and diffuse seismic sources. We back-project correlated seismic signals from the receivers back to their sources, assuming linear source to receiver paths and a known velocity model (obtained from ambient noise tomography). We apply polarization filters to isolate individual and concurrent geyser energy associated with P and S phases. We generate 4D, time-lapsed images of the geyser source field that illustrate how the source distribution changes through the eruption cycle. We compare images for pre-eruption, co-eruption, post-eruption and quiescent periods. We use our images to assess eruption mechanics in the system (i.e. top-down vs. bottom-up) and

  15. Iceberg calving as a primary source of regional‐scale glacier‐generated seismicity in the St. Elias Mountains, Alaska

    Science.gov (United States)

    O'Neel, Shad; Larsen, Christopher F.; Rupert, Natalia; Hansen, Roger

    2010-01-01

    Since the installation of the Alaska Regional Seismic Network in the 1970s, data analysts have noted nontectonic seismic events thought to be related to glacier dynamics. While loose associations with the glaciers of the St. Elias Mountains have been made, no detailed study of the source locations has been undertaken. We performed a two-step investigation surrounding these events, beginning with manual locations that guided an automated detection and event sifting routine. Results from the manual investigation highlight characteristics of the seismic waveforms including single-peaked (narrowband) spectra, emergent onsets, lack of distinct phase arrivals, and a predominant cluster of locations near the calving termini of several neighboring tidewater glaciers. Through these locations, comparison with previous work, analyses of waveform characteristics, frequency-magnitude statistics and temporal patterns in seismicity, we suggest calving as a source for the seismicity. Statistical properties and time series analysis of the event catalog suggest a scale-invariant process that has no single or simple forcing. These results support the idea that calving is often a response to short-lived or localized stress perturbations. Our results demonstrate the utility of passive seismic instrumentation to monitor relative changes in the rate and magnitude of iceberg calving at tidewater glaciers that may be volatile or susceptible to ensuing rapid retreat, especially when existing seismic infrastructure can be used.

  16. Identifying mid-water targets using the higher frequencies emitted by seismic sources of opportunity

    OpenAIRE

    Banda, Nikhil; Blondel, Philippe

    2016-01-01

    Seismic sources are routinely employed by the oil and gas industry to identify hydrocarbon reserves beneath the seabed, and by researchers to image the sub-seabed for geophysics and to identify geo-hazards such as tsunami-generating areas. For mitigation purposes, it is paramount to identify animals in the water column, but they can be missed by surface observations (if they are diving or in bad weather) or by Passive Acoustic Monitoring (if they remain silent). For operational reasons, it is...

  17. Source mechanisms of mining-related seismic events in the Far West Rand, South Africa

    CSIR Research Space (South Africa)

    Kassa, BB

    2009-09-01

    Full Text Available Meeting and Exhibition Swaziland, 16 - 18 September 2009, pages 69 - 72 Source mechanisms of mining-related seismic events in the Far West Rand, South Africa BB Kassa1, J Julià2, AA Nyblade2 and RJ Durrheim1,3 1University of the Witwatersrand... layer between the gold- bearing reefs, the forward problem can be formulated as [Trifu et al., 2000; Julia et al., 2009] u=cF:M where u = vector of spectral displacements, c = 1/(4pV3R), ρ = density, V = P- or S-wave velocity, R = hypocentral...

  18. Parametrically disciplined operation of a vibratory gyroscope

    Science.gov (United States)

    Shcheglov, Kirill V. (Inventor); Hayworth, Ken J. (Inventor); Challoner, A. Dorian (Inventor); Peay, Chris S. (Inventor)

    2008-01-01

    Parametrically disciplined operation of a symmetric nearly degenerate mode vibratory gyroscope is disclosed. A parametrically-disciplined inertial wave gyroscope having a natural oscillation frequency in the neighborhood of a sub-harmonic of an external stable clock reference is produced by driving an electrostatic bias electrode at approximately twice this sub-harmonic frequency to achieve disciplined frequency and phase operation of the resonator. A nearly symmetric parametrically-disciplined inertial wave gyroscope that can oscillate in any transverse direction and has more than one bias electrostatic electrode that can be independently driven at twice its oscillation frequency at an amplitude and phase that disciplines its damping to zero in any vibration direction. In addition, operation of a parametrically-disciplined inertial wave gyroscope is taught in which the precession rate of the driven vibration pattern is digitally disciplined to a prescribed non-zero reference value.

  19. Coriolis vibratory gyroscopes theory and design

    CERN Document Server

    Apostolyuk, Vladislav

    2016-01-01

    This book provides the latest theoretical analysis and design methodologies of different types of Coriolis vibratory gyroscopes (CVG). Together, the chapters analyze different types of sensitive element designs and their kinematics, derivation of motion equations, analysis of sensitive elements dynamics in modulated and demodulated signals, calculation and optimization of main performance characteristics, and signal processing and control. Essential aspects of numerical simulation of CVG using Simulink® are also covered. This is an ideal book for graduate students, researchers, and engineers working in fields that require gyroscope application, including but not limited to: inertial sensors and systems, automotive and consumer electronics, small unmanned aircraft control systems, personal mobile navigation systems and related software development, and augmented and virtual reality systems.

  20. Scenario-Based Seismic Risk Analysis: An Engineering Approach to the Development of Source and Site-Specific Ground Motion Time Histories in Areas of Low Seismicity

    Science.gov (United States)

    Klügel, Jens-Uwe; Attinger, Richard

    2011-01-01

    Modern engineering design methods require ground motion time histories as input for non-linear dynamic structural analysis. Non-linear dynamic methods of analysis are increasingly applied in the context of probabilistic risk assessments and for cost-effective design of critical infrastructures. In current engineering practice artificial time histories matching deterministic design spectra or probabilistic uniform hazard spectra are most frequently used for engineering analysis. The intermediate step of generation of response spectra can lead to a biased estimate of the potential damage from earthquakes because of insufficient consideration of the true energy content and strong motion duration of earthquakes. Thus, assessment of seismic risk may seem unrealistic. An engineering approach to the development of three-component ground motion time histories has been established which enables consideration of the typical characteristics of seismic sources, regional ground motion attenuation, and the main geotechnical characteristics of the target site. Therefore, the approach is suitable for use in scenario-based risk analysis a larger number of time histories are required for representation of the seismic hazard. Near-field effects are implemented in the stochastic source model using engineering approximations. The approach is suggested for use in areas of low seismicity where ground motion records of larger earthquakes are not available. Uncertainty analysis indicates that ground motions generated by individual earthquakes are well constrained and that the usual lognormal model is not the best choice for predicting the upper tail of the distribution of the ground motions.

  1. Blind Source Separation of Seismic Events with Independent Component Analysis: CTBT related exercise

    Science.gov (United States)

    Rozhkov, Mikhail; Kitov, Ivan

    2015-04-01

    Blind Source Separation (BSS) methods used in signal recovery applications are attractive for they use minimal a priori information about the signals they are dealing with. Homomorphic deconvolution and cepstrum estimation are probably the only methods used in certain extent in CTBT applications that can be attributed to the given branch of technology. However Expert Technical Analysis (ETA) conducted in CTBTO to improve the estimated values for the standard signal and event parameters according to the Protocol to the CTBT may face problems which cannot be resolved with certified CTBTO applications and may demand specific techniques not presently used. The problem to be considered within the ETA framework is the unambiguous separation of signals with close arrival times. Here, we examine two scenarios of interest: (1) separation of two almost co-located explosions conducted within fractions of seconds, and (2) extraction of explosion signals merged with wavetrains from strong earthquake. The importance of resolving the problem related to case 1 is connected with the correct explosion yield estimation. Case 2 is a well-known scenario of conducting clandestine nuclear tests. While the first case can be approached somehow with the means of cepstral methods, the second case can hardly be resolved with the conventional methods implemented at the International Data Centre, especially if the signals have close slowness and azimuth. Independent Component Analysis (in its FastICA implementation) implying non-Gaussianity of the underlying processes signal's mixture is a blind source separation method that we apply to resolve the mentioned above problems. We have tested this technique with synthetic waveforms, seismic data from DPRK explosions and mining blasts conducted within East-European platform as well as with signals from strong teleseismic events (Sumatra, April 2012 Mw=8.6, and Tohoku, March 2011 Mw=9.0 earthquakes). The data was recorded by seismic arrays of the

  2. Multiple coincident eruptive seismic tremor sources during the 2014-2015 eruption at Holuhraun, Iceland

    Science.gov (United States)

    Eibl, Eva P. S.; Bean, Christopher J.; Jónsdóttir, Ingibjörg; Höskuldsson, Armann; Thordarson, Thorvaldur; Coppola, Diego; Witt, Tanja; Walter, Thomas R.

    2017-04-01

    We analyze eruptive tremor during one of the largest effusive eruptions in historical times in Iceland (2014/2015 Holuhraun eruption). Seismic array recordings are compared with effusion rates deduced from Moderate Resolution Imaging Spectroradiometer recordings and ground video monitoring data and lead to the identification of three coexisting eruptive tremor sources. This contrasts other tremor studies that generally link eruptive tremor to only one source usually associated with the vent. The three sources are (i) a source that is stable in back azimuth and shows bursts with ramp-like decrease in amplitude at the beginning of the eruption: we link it to a process below the open vents where the bursts correlate with the opening of new vents and temporary increases in the lava fountaining height; (ii) a source moving by a few degrees per month while the tremor amplitude suddenly increases and decreases: back azimuth and slowness correlate with the growing margins of the lava flow field, whilst new contact with a river led to fast increases of the tremor amplitude; and (iii) a source moving by up to 25° southward in 4 days that cannot be related to any observed surface activity and might be linked to intrusions. We therefore suggest that eruptive tremor amplitudes/energies are used with caution when estimating eruptive volumes, effusion rates, or the eruption explosivity as multiple sources can coexist during the eruption phase. Our results suggest that arrays can monitor both the growth of a lava flow field and the activity in the vents.

  3. Application of multi-stage, multi-disk type downhole seismic source; Tadanshiki taso enbangata koseinai shingen no tekiyosei

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, N. [Japan National Oil Corp., Tokyo (Japan); Shoji, Y. [Oyo Corp., Tokyo (Japan)

    1997-05-27

    A multi-stage, multi-disk type seismic source was developed as a downhole seismic source. The seismic source is an improved version of the downhole seismic source of a system in which an elastic wave is generated by a weight accelerated by restitutive force of a spring striking the upper part of a laminated structure consisted of metal disks and elastic bodies installed in water in a well. Enhancing the vibration exciting efficiency requires impedance radiated from the disks to be increased. The multi-disk structure was adopted because of restrictions on the disk area under the limiting condition of being inside the well. Further limitation has still existed, which led to finally structuring the multi-disk type to a multi-stage construction to increase the radiated impedance. In order to increase average velocity on the radiation surface, mass relationship between the hammer and the anvil was sought so that the maximum velocity is achieved at the process of converting motion energies among the hammer, anvil and disks. The anvil mass may sufficiently be 50% to 100% of the hammer mass. The equipment was installed in an actual oil well for testing. This seismic source was verified to have sufficient applicability in the cross hole measurement. 5 refs., 7 figs., 1 tab.

  4. Seismic Source Mechanism of Gas-Piston Activity at Kilauea Inferred from Inversion of Broadband Waveforms

    Science.gov (United States)

    Chouet, B. A.; Dawson, P. B.

    2015-12-01

    Among the broad range of magmatic processes observed in the Overlook pit crater in Kilauea Caldera are recurring episodes of gas-piston activity. This activity is accompanied by repetitive seismic signals recorded by a broadband network deployed in the summit caldera. We use the seismic data to model the source mechanism of representative gas-piston events in a sequence that occurred on 20-25 August 2011 during a gentle inflation of the Kilauea summit. We apply a new waveform inversion method that accounts for the contributions from both translation and tilt in horizontal seismograms through the use of Green's functions representing the seismometer response to translation and tilt ground motions. This method enables a robust description of the source mechanism over the period range of 1 - 10,000 s. Most of the seismic wave field produced by gas-pistoning originates in a source region ~1 km below the eastern perimeter of Halema'uma'u pit crater. The observed waveforms are well explained by a simple volumetric source with geometry composed of two intersecting cracks featuring an east-striking crack (dike) dipping 80° to the north, intersecting a north-striking crack (inclined sheet) dipping 65° to the east. Each gas-piston event is characterized by a rapid inflation lasting a few minutes trailed by a slower deflation ramp extending up to 15 minutes, attributed to the efficient coupling at the source centroid location of the pressure and momentum changes accompanying the growth and collapse of a layer of foam at the top of the magma column. Assuming a simple lumped parameter representation of the shallow magmatic system, the observed pressure and volume variations can be modeled with the following attributes: foam thickness (10 - 50 m), foam cell diameter (0.04 - 0.10 m), and gas-injection velocity (0.01 - 0.06 m s-1). Based on the change in the period of very-long-period oscillations accompanying the onset of the gas-piston signal and tilt evidence, the height of

  5. Modification of piezoelectric vibratory gyroscope resonator parameters by feedback control

    CSIR Research Space (South Africa)

    Loveday, PW

    1998-09-01

    Full Text Available A method for analyzing the effect of feedback control on the dynamics of piezoelectric resonators used in vibratory gyroscopes has been developed. This method can be used to determine the feasibility of replacing the traditional mechanical balancing...

  6. Vibratory gyroscopes : identification of mathematical model from test data

    CSIR Research Space (South Africa)

    Shatalov, MY

    2007-05-01

    Full Text Available Simple mathematical model of vibratory gyroscopes imperfections is formulated, which includes anisotropic damping and variation of mass-stiffness parameters and their harmonics. The method of identification of parameters of the mathematical model...

  7. Seismic source spectral properties of crack-like and pulse-like modes of dynamic rupture

    Science.gov (United States)

    Wang, Yongfei; Day, Steven M.

    2017-08-01

    Earthquake source properties such as seismic moment and stress drop are routinely estimated from far-field body wave amplitude spectra. Some quantitative but model-dependent relations have been established between seismic spectra and source parameters. However, large variability is seen in the parameter estimates, and it is uncertain how the variability is partitioned among real variability in the source parameters, observational error, and modeling error due to complexity of earthquake behaviors. Earthquake models with dynamic weakening have been found to exhibit two different modes of rupture: expanding-crack and self-healing pulse modes. Four representative models are generated to model the transition from crack-like to pulse-like. Pulse-like rupture leads to development of a second corner frequency, and the intermediate spectral slope is approximately 2 in most cases. The focal-sphere-averaged lower P and S wave corner frequencies are systematically higher for pulse-like models than crack models of comparable rupture velocity. The slip-weighted stress drop ΔσE exceeds the moment-based stress drop ΔσM for pulse-like ruptures, with the ratio ranging from about 1.3 to 1.65, while they are equal for the crack-like case. The variations in rupture mode introduce variability of the order of a factor of 2 in standard (i.e., crack model-based) spectral estimates of stress drop. The transition from arresting- to growing-pulse rupture is accompanied by a large (factor of ˜1.6) increase in the radiation ratio. Thus, variations in rupture mode may account for the portion of the scatter in observational spectral estimates of source parameters.

  8. Configuration System for Simulation Based Design of Vibratory Bowl Feeders

    DEFF Research Database (Denmark)

    Hansson, Michael Natapon; Mathiesen, Simon; Ellekilde, Lars-Peter

    2017-01-01

    Vibratory bowl feeders are still among the most commonly used production equipment for automated part feeding, where parts are correctly oriented for further manipulation by being conveyed through a set of orienting devices. Designing vibratory bowl feeders involves selecting and sequencing a num...... the configuration task. To test the approach, the configuration system is used to find three device sequences for feeding three parts in specific orientations. The sequences are validated through simulation and real world experiments, showing good consistency....

  9. The Seismic Sources of the 2009 Samoa Earthquake from Tsunami Simulation

    Science.gov (United States)

    Lai, P.-Y.; Chao, B. F.; Chang, E. T.-Y.; Wu, T.-R.

    2012-04-01

    A big earthquake occurred in the Samoa-Tonga region on September 29, 2009, as the Pacific plate subducts westward beneath the Australia plate along the Tonga trench. The earthquake was recognized as a multiple-source event, but two distinct sets of rupture solutions have been presented: Deducing only from the seismic data, Lay et al. (2010) resolved this instance as an initiation of an intraplate normal faulting (Mw8.1) triggering the two underthrusting subevents (both in Mw7.8); whereas Beaven et al. (2010) presented that the normal fault (Mw7.9) was triggered by the slow thrusting of the interplate motion (Mw8.0), determined from various types of data including tsunami waves. Here, we explore whether and how much the simulations of tsunamis can help discriminating the seismic source solutions. The program COMCOT is used to model the tsunami waves and propagation. The simulated waveforms are compared with the actual observations from three ocean bottom pressure recorders of DART project (Deep-ocean Assessment Reporting of Tsunamis, developed by NOAA). We apply the two afore-mentioned rupture models to determine the respective initial conditions and the radial spreading of the tsunami waves. According to the tsunami waveform simulation, the tsunami waves are the sea-surface perturbation provoked by the large normal fault and the relatively minor thrusts, but in varied weightings of normal-to-thrust mechanism at different DART stations. Simulating with two rupture models for the normal fault provided by Lay et al., it favors the geometry of the normal fault of dipping to northeast, reverse to the commonly thought trench-ward image. This is consistent with the one determined by Beaven et al. Based on our experience, a detailed rupture description can draw a better approximation in tsunami simulation. However, the tsunami simulation cannot discriminate the variation of source mechanisms in the sense that the seismic source time functions processing within one or two

  10. Seismic attenuation structure of the Seattle Basin, Washington State from explosive-source refraction data

    Science.gov (United States)

    Li, Q.; Wilcock, W.S.D.; Pratt, T.L.; Snelson, C.M.; Brocher, T.M.

    2006-01-01

    We used waveform data from the 1999 SHIPS (Seismic Hazard Investigation of Puget Sound) seismic refraction experiment to constrain the attenuation structure of the Seattle basin, Washington State. We inverted the spectral amplitudes of compressional- and shear-wave arrivals for source spectra, site responses, and one- and two-dimensional Q-1 models at frequencies between 1 and 40 Hz for P waves and 1 and 10 Hz for S waves. We also obtained Q-1 models from t* values calculated from the spectral slopes of P waves between 10 and 40 Hz. One-dimensional inversions show that Qp at the surface is 22 at 1 Hz, 130 at 5 Hz, and 390 at 20 Hz. The corresponding values at 18 km depth are 100, 440, and 1900. Qs at the surface is 16 and 160 at 1 Hz and 8 Hz, respectively, increasing to 80 and 500 at 18 km depth. The t* inversion yields a Qp model that is consistent with the amplitude inversions at 20 and 30 Hz. The basin geometry is clearly resolved in the t* inversion, but the amplitude inversions only imaged the basin structure after removing anomalously high-amplitude shots near Seattle. When these shots are removed, we infer that Q-1 values may be ???30% higher in the center of the basin than the one-dimensional models predict. We infer that seismic attenuation in the Seattle basin will significantly reduce ground motions at frequencies at and above 1 Hz, partially countering amplification effects within the basin.

  11. Estimating the 2008 Quetame (Colombia) earthquake source parameters from seismic data and InSAR measurements

    Science.gov (United States)

    Dicelis, Gabriel; Assumpção, Marcelo; Kellogg, James; Pedraza, Patricia; Dias, Fábio

    2016-12-01

    Seismic waveforms and geodetic measurements (InSAR) were used to determine the location, focal mechanism and coseismic surface displacements of the Mw 5.9 earthquake which struck the center of Colombia on May 24, 2008. We determined the focal mechanism of the main event using teleseismic P wave arrivals and regional waveform inversion for the moment tensor. We relocated the best set of aftershocks (30 events) with magnitudes larger than 2.0 recorded from May to June 2008 by a temporary local network as well as by stations of the Colombia national network. We successfully estimated coseismic deformation using SAR interferometry, despite distortion in some areas of the interferogram by atmospheric noise. The deformation was compared to synthetic data for rectangular dislocations in an elastic half-space. Nine source parameters (strike, dip, length, width, strike-slip deformation, dip-slip deformation, latitude shift, longitude shift, and minimum depth) were inverted to fit the observed changes in line-of-sight (LOS) toward the satellite four derived parameters were also estimated (rake, average slip, maximum depth and seismic moment). The aftershock relocation, the focal mechanism and the coseismic dislocation model agree with a right-lateral strike-slip fault with nodal planes oriented NE-SW and NW-SE. We use the results of the waveform inversion, radar interferometry and aftershock relocations to identify the high-angle NE-SW nodal plane as the primary fault. The inferred subsurface rupture length is roughly 11 km, which is consistent with the 12 km long distribution of aftershocks. This coseismic model can provide insights on earthquake mechanisms and seismic hazard assessments for the area, including the 8 million residents of Colombia's nearby capital city Bogota. The 2008 Quetame earthquake appears to be associated with the northeastward "escape" of the North Andean block, and it may help to illuminate how margin-parallel shear slip is partitioned in the

  12. Three-Dimensional Velocity Model of the Los Angeles Region From Active Source Seismic Data

    Science.gov (United States)

    Schramm, K. A.; Miller, K.; Okaya, D.; Fuis, G.

    2002-12-01

    In 1994, the USGS, along with several other institutions, ran an active source seismic survey through the Los Angeles basin, known as the Los Angeles Region Seismic Experiment (LARSE). This experiment had both offshore and onshore shots and receivers which were arranged in 3 lines, each crossing over or near the site of a major (M > 6.5) earthquake epicenter. The offshore component consisted of airgun shots recorded by onshore receivers, ocean bottom seismometers, and a digital streamer. The shots for this portion totaled 25,000, recorded by 10 OBS, a 160 4.2 km digital streamer and 170 single component Reftek DAS units. The on-shore component contained 62 shots along transect 1, recorded by 228 3-component Reftek DAS units, 187 single component SGR's, 183 single component PRS1's, 33 three-component PRS4's, and 18 three-component GEOS's. The goal of LARSE was to produce better images of basins in the the Los Angeles area than that produced by earthquake data. Here, we present a tomographic 3-D velocity model produced by inverting LARSE first arrival refraction travel time picks using the 'First Arrival Seismic Tomography Code (FAST)' (Zelt and Barton, 1998). 3-D ray coverage is best near the western edge of the Los Angeles basin, where the airgun data is recored by seismometers on all three lines. For the rest of the model, there is good 2-D coverage along the ends of the lines. Structures that are imaged include the Santa Monica Basin, the Palos Verdes Fault, the western edge of the Los Angeles Basin, and the San Andreas fault. The sensitivity of the model to perturbations of travel times was tested using the method of Doser et al. (1998). The model is then compared to other published models in order to enhance the understanding of the structures that underlay and surround the Los Angeles Basin.

  13. Optimization of vibratory welding process parameters using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Pravin Kumar; Kumar, S. Deepak; Patel, D.; Prasad, S. B. [National Institute of Technology Jamshedpur, Jharkhand (India)

    2017-05-15

    The current investigation was carried out to study the effect of vibratory welding technique on mechanical properties of 6 mm thick butt welded mild steel plates. A new concept of vibratory welding technique has been designed and developed which is capable to transfer vibrations, having resonance frequency of 300 Hz, into the molten weld pool before it solidifies during the Shielded metal arc welding (SMAW) process. The important process parameters of vibratory welding technique namely welding current, welding speed and frequency of the vibrations induced in molten weld pool were optimized using Taguchi’s analysis and Response surface methodology (RSM). The effect of process parameters on tensile strength and hardness were evaluated using optimization techniques. Applying RSM, the effect of vibratory welding parameters on tensile strength and hardness were obtained through two separate regression equations. Results showed that, the most influencing factor for the desired tensile strength and hardness is frequency at its resonance value, i.e. 300 Hz. The micro-hardness and microstructures of the vibratory welded joints were studied in detail and compared with those of conventional SMAW joints. Comparatively, uniform and fine grain structure has been found in vibratory welded joints.

  14. Error Model and Compensation of Bell-Shaped Vibratory Gyro.

    Science.gov (United States)

    Su, Zhong; Liu, Ning; Li, Qing

    2015-09-17

    A bell-shaped vibratory angular velocity gyro (BVG), inspired by the Chinese traditional bell, is a type of axisymmetric shell resonator gyroscope. This paper focuses on development of an error model and compensation of the BVG. A dynamic equation is firstly established, based on a study of the BVG working mechanism. This equation is then used to evaluate the relationship between the angular rate output signal and bell-shaped resonator character, analyze the influence of the main error sources and set up an error model for the BVG. The error sources are classified from the error propagation characteristics, and the compensation method is presented based on the error model. Finally, using the error model and compensation method, the BVG is calibrated experimentally including rough compensation, temperature and bias compensation, scale factor compensation and noise filter. The experimentally obtained bias instability is from 20.5°/h to 4.7°/h, the random walk is from 2.8°/h(1/2) to 0.7°/h(1/2) and the nonlinearity is from 0.2% to 0.03%. Based on the error compensation, it is shown that there is a good linear relationship between the sensing signal and the angular velocity, suggesting that the BVG is a good candidate for the field of low and medium rotational speed measurement.

  15. Experimental monitoring of the hydro-mechanical state of a discontinuity using controlled source seismic method

    Science.gov (United States)

    Place, Joachim; Blake, Oshaine; Rietbrock, Andreas; Faulkner, Dan

    2013-04-01

    Great earthquakes often occur in crystalline rocks, and basement rocks can host geothermal and hydrocarbon resources. In such rocks, the fluid storage and transfer properties depend mainly on the natural fault and fracture networks. Therefore, it is of primary importance to characterise the physical properties of the fault zones in order to better understand the seismogenic processes and how the resources can be exploited. Seismic waves are known to be sensitive to many parameters which evolve depending on the fault response to stresses and fluid type. Therefore seismic methods show a great potential to monitor the hydro-mechanical state of structures remotely, with no need for drilling through the structures. We developed a basic experimental approach at sample scale to monitor the mechanical coupling through a discontinuity between a granite sample in contact with a piece of steel, when the effective pressure (Peff) and the nature of the filling fluid vary. Piezoceramics utilised both as sources and sensors are located on the steel (in which the attenuation is assumed to be zero) and both generate and record the P and S wave fields reflected off the discontinuity at normal incidence. This permits the normal (Bn) and tangential (Bt) fracture compliances to be calculated after Schoenberg's linear slip theory from the measurement of P-P and S-S reflection coefficients. The roughness of the sample surface, as well as the effect of fluid type (air or water) and Peff were studied. Under dry conditions, it is observed that the poorer the contact area, the higher Bn and Bt, meaning that the seismic energy of P and S waves is less transmitted. Increasing the effective pressure decreases the compliances, which is interpreted as the effect of the closure of the voids at the interface; this permits more seismic energy to be transmitted through the interface. It is also observed that Bn is significantly higher than Bt at low Peff (energy of compressional waves through the

  16. Seismic Source Process and Strong Ground Motion of 1920-Haiyuan Earthquake

    Science.gov (United States)

    Xu, X.; Zhang, Z.; Chen, X.

    2016-12-01

    The 16 December 1920 Haiyuan earthquake (M=7.8 8.3), which occurred near Gan-yanchi along the Haiyuan fault, was one of the largest devastating intraplate earthquakes in China and even in the world. The maximum epicentral intensity reached XI degree. Deng et al. (1989) found nearly 237km surface rupture and 10-11m maximum sinistral strike-slip dislocation in their geological survey. The seismogenic fault (Haiyuan fault) which is located in the northeast Tibetan Plateau, is extremely complex due to the crustal deformation. Many researchers have studied this earthquake and the seismogenic fault by magnetotelluric sounding, deep seismic reflection profile, LiDAR, GPS, InSAR and trenching, etc. However, Because of few seismic recordings available in Haiyuan earthquake, the detailed rupture mechanisms and hazard distribution need to further scientifically analyze. In order to figure out the rupture mechanism of 1920 Haiyuan earthquake, we use two popular methods to model the earthquake source. One is the characterized source model which is based on asperity model. This model can summarize the main features of the rupture process and more in-deep research. Another one is the dynamic rupture model which is based on earthquake source physics. The method can simulate the process of earthquake rupture initiation, extension and termination. Zhang et al. (2014) have studied the 3-D dynamic rupture process on non-planar fault using 3D curved-grid finite-difference method (CG-FDM) which is flexible in modeling a fault with complex geometry and have successfully simulated the dynamic rupture of Wenchuan earthquake. In this work, we build reasonable kinematic and dynamic models based on previous investigations including tectonic stress, friction parameters, co-seismic displacement, and so on. Then, the strong ground motion of Haiyuan earthquake is simulated by CG-FDM. Finally, we analyze the synthetic intensity distribution and the effect on the stress distribution around this

  17. An Analysis of the Seismic Source Characteristics of Explosions in Low-Coupling Dry Porous Media (Postprint)

    Science.gov (United States)

    2011-12-30

    tectonic source region, explosions in dry, porous media are typically observed to have, at a given yield, mb values lower than those in hard rock by...mb/yield relation for any fixed tectonic source region, explosions in dry, porous media, such as the dry tuffs and alluvium found above the water...formulation of seismic source models for underground nuclear explosions in granite, saturated tuff/rhyolite, salt , and sandstone/shale media. The models

  18. Shotgun use as high resolution seismic source; Uso de rifle como fonte sismica para alta resolucao

    Energy Technology Data Exchange (ETDEWEB)

    Antunes, Paulo de Tarso Silva; Guimaraes, Marco Antonio Gallotti [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    1993-07-01

    This paper relates the performance of the 8 and 12 gauge Betsy shotgun , under different geological conditions in the Santa Fe (RN) and Camaqua (RS) regions, in Brazil. The data are presented in field seismograms, amplitude spectra and a bar graph, for evaluations of generated energy levels and frequency content. Shown are also tables of the general characteristics of the Betsy shotgun and of the data acquisition parameters, besides a picture of the shotgun. It is concluded that the shotgun is a good tool for shallow seismic reflection surveys, with advantages of being extremely lightweight, portable, of low cost and capable of producing high-frequency energy. Due to strong dependence of geological characteristics of the site, a better performance of the source was observed in the Camaqua region. (author)

  19. An open-source Matlab code package for improved rank-reduction 3D seismic data denoising and reconstruction

    Science.gov (United States)

    Chen, Yangkang; Huang, Weilin; Zhang, Dong; Chen, Wei

    2016-10-01

    Simultaneous seismic data denoising and reconstruction is a currently popular research subject in modern reflection seismology. Traditional rank-reduction based 3D seismic data denoising and reconstruction algorithm will cause strong residual noise in the reconstructed data and thus affect the following processing and interpretation tasks. In this paper, we propose an improved rank-reduction method by modifying the truncated singular value decomposition (TSVD) formula used in the traditional method. The proposed approach can help us obtain nearly perfect reconstruction performance even in the case of low signal-to-noise ratio (SNR). The proposed algorithm is tested via one synthetic and field data examples. Considering that seismic data interpolation and denoising source packages are seldom in the public domain, we also provide a program template for the rank-reduction based simultaneous denoising and reconstruction algorithm by providing an open-source Matlab package.

  20. Scalable Metadata Management for a Large Multi-Source Seismic Data Repository

    Energy Technology Data Exchange (ETDEWEB)

    Gaylord, J. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dodge, D. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Magana-Zook, S. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Barno, J. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Knapp, D. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-04-11

    In this work, we implemented the key metadata management components of a scalable seismic data ingestion framework to address limitations in our existing system, and to position it for anticipated growth in volume and complexity. We began the effort with an assessment of open source data flow tools from the Hadoop ecosystem. We then began the construction of a layered architecture that is specifically designed to address many of the scalability and data quality issues we experience with our current pipeline. This included implementing basic functionality in each of the layers, such as establishing a data lake, designing a unified metadata schema, tracking provenance, and calculating data quality metrics. Our original intent was to test and validate the new ingestion framework with data from a large-scale field deployment in a temporary network. This delivered somewhat unsatisfying results, since the new system immediately identified fatal flaws in the data relatively early in the pipeline. Although this is a correct result it did not allow us to sufficiently exercise the whole framework. We then widened our scope to process all available metadata from over a dozen online seismic data sources to further test the implementation and validate the design. This experiment also uncovered a higher than expected frequency of certain types of metadata issues that challenged us to further tune our data management strategy to handle them. Our result from this project is a greatly improved understanding of real world data issues, a validated design, and prototype implementations of major components of an eventual production framework. This successfully forms the basis of future development for the Geophysical Monitoring Program data pipeline, which is a critical asset supporting multiple programs. It also positions us very well to deliver valuable metadata management expertise to our sponsors, and has already resulted in an NNSA Office of Defense Nuclear Nonproliferation

  1. Imaging the site of the Source Physics Experiment using seismic interferometry

    Science.gov (United States)

    Matzel, E.; Mellors, R. J.; Pitarka, A.

    2013-12-01

    The Source Physics Experiment (SPE) is a series of precisely designed explosions recorded by a dense network of seismometers. Its purpose is to obtain a physics-based understanding of how seismic waves are created at and scattered near the source. In order to separate source-specific effects from those due to geological heterogeneity, we need a precise picture of the subsurface. In this study, we are using several methods of seismic interferometry to obtain highly detailed images of the SPE site. Coda wave interferometry (CI) uses the diffuse coda from earthquakes or explosions as a source of coherent energy. Ambient noise correlation (ANC) uses the energy of the ambient background field. In each technique, the data recorded at one seismometer are correlated with the data recorded at another to obtain an estimate of the Green's function (GF) between the two. More than 150 instruments were deployed around the site, predominantly along 5 lines extending radially outward from the shot point. Most of those are located within 2 km. We used the records of one of the SPE shots as an energy source for the CI technique and 3 months of high gain continuous data for ANC. Each technique has advantages over the other. CI is very fast (only a few minutes of data are needed, compared to the weeks to years of continuous data often required for ANC), and the GF obtained has the same frequency content as the original shot (while the spectrum of ANC is determined by the natural background noise). Using CI on the SPE data, we obtain very good quality estimate of the GF to very high frequency. The key disadvantages of CI are that we can only correlate energy propagating radially outward and the source point itself is hidden. ANC requires more data and processing time, but allows us to estimate the GF between any two of the seismometers. By combining the two techniques, we obtain a very sharp image of seismic velocity and attenuation in the upper several kilometers beneath the site

  2. Microseismic monitoring of soft-rock landslide: contribution of a 3D velocity model for the location of seismic sources.

    Science.gov (United States)

    Floriane, Provost; Jean-Philippe, Malet; Cécile, Doubre; Julien, Gance; Alessia, Maggi; Agnès, Helmstetter

    2015-04-01

    Characterizing the micro-seismic activity of landslides is an important parameter for a better understanding of the physical processes controlling landslide behaviour. However, the location of the seismic sources on landslides is a challenging task mostly because of (a) the recording system geometry, (b) the lack of clear P-wave arrivals and clear wave differentiation, (c) the heterogeneous velocities of the ground. The objective of this work is therefore to test whether the integration of a 3D velocity model in probabilistic seismic source location codes improves the quality of the determination especially in depth. We studied the clay-rich landslide of Super-Sauze (French Alps). Most of the seismic events (rockfalls, slidequakes, tremors...) are generated in the upper part of the landslide near the main scarp. The seismic recording system is composed of two antennas with four vertical seismometers each located on the east and west sides of the seismically active part of the landslide. A refraction seismic campaign was conducted in August 2014 and a 3D P-wave model has been estimated using the Quasi-Newton tomography inversion algorithm. The shots of the seismic campaign are used as calibration shots to test the performance of the different location methods and to further update the 3D velocity model. Natural seismic events are detected with a semi-automatic technique using a frequency threshold. The first arrivals are picked using a kurtosis-based method and compared to the manual picking. Several location methods were finally tested. We compared a non-linear probabilistic method coupled with the 3D P-wave model and a beam-forming method inverted for an apparent velocity. We found that the Quasi-Newton tomography inversion algorithm provides results coherent with the original underlaying topography. The velocity ranges from 500 m.s-1 at the surface to 3000 m.s-1 in the bedrock. For the majority of the calibration shots, the use of a 3D velocity model

  3. Tsunami hazard at the Western Mediterranean Spanish coast from seismic sources

    Directory of Open Access Journals (Sweden)

    J. A. Álvarez-Gómez

    2011-01-01

    Full Text Available Spain represents an important part of the tourism sector in the Western Mediterranean, which has been affected in the past by tsunamis. Although the tsunami risk at the Spanish coasts is not the highest of the Mediterranean, the necessity of tsunami risk mitigation measures should not be neglected. In the Mediterranean area, Spain is exposed to two different tectonic environments with contrasting characteristics. On one hand, the Alboran Basin characterised by transcurrent and transpressive tectonics and, on the other hand, the North Algerian fold and thrust belt, characterised by compressive tectonics. A set of 22 seismic tsunamigenic sources has been used to estimate the tsunami threat over the Spanish Mediterranean coast of the Iberian peninsula and the Balearic Islands. Maximum wave elevation maps and tsunami travel times have been computed by means of numerical modelling and we have obtained estimations of threat levels for each source over the Spanish coast. The sources on the Western edge of North Algeria are the most dangerous, due to their threat to the South-Eastern coast of the Iberian Peninsula and to the Western Balearic Islands. In general, the Northern Algerian sources pose a greater risk to the Spanish coast than the Alboran Sea sources, which only threaten the peninsular coast. In the Iberian Peninsula, the Spanish provinces of Almeria and Murcia are the most exposed, while all the Balearic Islands can be affected by the North Algerian sources with probable severe damage, specially the islands of Ibiza and Minorca. The results obtained in this work are useful to plan future regional and local warning systems, as well as to set the priority areas to conduct research on detailed tsunami risk.

  4. Tsunami hazard at the Western Mediterranean Spanish coast from seismic sources

    Science.gov (United States)

    Álvarez-Gómez, J. A.; Aniel-Quiroga, Í.; González, M.; Otero, L.

    2011-01-01

    Spain represents an important part of the tourism sector in the Western Mediterranean, which has been affected in the past by tsunamis. Although the tsunami risk at the Spanish coasts is not the highest of the Mediterranean, the necessity of tsunami risk mitigation measures should not be neglected. In the Mediterranean area, Spain is exposed to two different tectonic environments with contrasting characteristics. On one hand, the Alboran Basin characterised by transcurrent and transpressive tectonics and, on the other hand, the North Algerian fold and thrust belt, characterised by compressive tectonics. A set of 22 seismic tsunamigenic sources has been used to estimate the tsunami threat over the Spanish Mediterranean coast of the Iberian peninsula and the Balearic Islands. Maximum wave elevation maps and tsunami travel times have been computed by means of numerical modelling and we have obtained estimations of threat levels for each source over the Spanish coast. The sources on the Western edge of North Algeria are the most dangerous, due to their threat to the South-Eastern coast of the Iberian Peninsula and to the Western Balearic Islands. In general, the Northern Algerian sources pose a greater risk to the Spanish coast than the Alboran Sea sources, which only threaten the peninsular coast. In the Iberian Peninsula, the Spanish provinces of Almeria and Murcia are the most exposed, while all the Balearic Islands can be affected by the North Algerian sources with probable severe damage, specially the islands of Ibiza and Minorca. The results obtained in this work are useful to plan future regional and local warning systems, as well as to set the priority areas to conduct research on detailed tsunami risk.

  5. Probabilistic tsunami hazard assessment at Seaside, Oregon, for near-and far-field seismic sources

    Science.gov (United States)

    Gonzalez, F.I.; Geist, E.L.; Jaffe, B.; Kanoglu, U.; Mofjeld, H.; Synolakis, C.E.; Titov, V.V.; Areas, D.; Bellomo, D.; Carlton, D.; Horning, T.; Johnson, J.; Newman, J.; Parsons, T.; Peters, R.; Peterson, C.; Priest, G.; Venturato, A.; Weber, J.; Wong, F.; Yalciner, A.

    2009-01-01

    The first probabilistic tsunami flooding maps have been developed. The methodology, called probabilistic tsunami hazard assessment (PTHA), integrates tsunami inundation modeling with methods of probabilistic seismic hazard assessment (PSHA). Application of the methodology to Seaside, Oregon, has yielded estimates of the spatial distribution of 100- and 500-year maximum tsunami amplitudes, i.e., amplitudes with 1% and 0.2% annual probability of exceedance. The 100-year tsunami is generated most frequently by far-field sources in the Alaska-Aleutian Subduction Zone and is characterized by maximum amplitudes that do not exceed 4 m, with an inland extent of less than 500 m. In contrast, the 500-year tsunami is dominated by local sources in the Cascadia Subduction Zone and is characterized by maximum amplitudes in excess of 10 m and an inland extent of more than 1 km. The primary sources of uncertainty in these results include those associated with interevent time estimates, modeling of background sea level, and accounting for temporal changes in bathymetry and topography. Nonetheless, PTHA represents an important contribution to tsunami hazard assessment techniques; viewed in the broader context of risk analysis, PTHA provides a method for quantifying estimates of the likelihood and severity of the tsunami hazard, which can then be combined with vulnerability and exposure to yield estimates of tsunami risk. Copyright 2009 by the American Geophysical Union.

  6. Contribution of Satellite Gravimetry to Understanding Seismic Source Processes of the 2011 Tohoku-Oki Earthquake

    Science.gov (United States)

    Han, Shin-Chan; Sauber, Jeanne; Riva, Riccardo

    2011-01-01

    The 2011 great Tohoku-Oki earthquake, apart from shaking the ground, perturbed the motions of satellites orbiting some hundreds km away above the ground, such as GRACE, due to coseismic change in the gravity field. Significant changes in inter-satellite distance were observed after the earthquake. These unconventional satellite measurements were inverted to examine the earthquake source processes from a radically different perspective that complements the analyses of seismic and geodetic ground recordings. We found the average slip located up-dip of the hypocenter but within the lower crust, as characterized by a limited range of bulk and shear moduli. The GRACE data constrained a group of earthquake source parameters that yield increasing dip (7-16 degrees plus or minus 2 degrees) and, simultaneously, decreasing moment magnitude (9.17-9.02 plus or minus 0.04) with increasing source depth (15-24 kilometers). The GRACE solution includes the cumulative moment released over a month and demonstrates a unique view of the long-wavelength gravimetric response to all mass redistribution processes associated with the dynamic rupture and short-term postseismic mechanisms to improve our understanding of the physics of megathrusts.

  7. When probabilistic seismic hazard climbs volcanoes: the Mt. Etna case, Italy - Part 1: Model components for sources parameterization

    Science.gov (United States)

    Azzaro, Raffaele; Barberi, Graziella; D'Amico, Salvatore; Pace, Bruno; Peruzza, Laura; Tuvè, Tiziana

    2017-11-01

    The volcanic region of Mt. Etna (Sicily, Italy) represents a perfect lab for testing innovative approaches to seismic hazard assessment. This is largely due to the long record of historical and recent observations of seismic and tectonic phenomena, the high quality of various geophysical monitoring and particularly the rapid geodynamics clearly demonstrate some seismotectonic processes. We present here the model components and the procedures adopted for defining seismic sources to be used in a new generation of probabilistic seismic hazard assessment (PSHA), the first results and maps of which are presented in a companion paper, Peruzza et al. (2017). The sources include, with increasing complexity, seismic zones, individual faults and gridded point sources that are obtained by integrating geological field data with long and short earthquake datasets (the historical macroseismic catalogue, which covers about 3 centuries, and a high-quality instrumental location database for the last decades). The analysis of the frequency-magnitude distribution identifies two main fault systems within the volcanic complex featuring different seismic rates that are controlled essentially by volcano-tectonic processes. We discuss the variability of the mean occurrence times of major earthquakes along the main Etnean faults by using an historical approach and a purely geologic method. We derive a magnitude-size scaling relationship specifically for this volcanic area, which has been implemented into a recently developed software tool - FiSH (Pace et al., 2016) - that we use to calculate the characteristic magnitudes and the related mean recurrence times expected for each fault. Results suggest that for the Mt. Etna area, the traditional assumptions of uniform and Poissonian seismicity can be relaxed; a time-dependent fault-based modeling, joined with a 3-D imaging of volcano-tectonic sources depicted by the recent instrumental seismicity, can therefore be implemented in PSHA maps

  8. Application of the finite-difference contrast-source inversion algorithm to seismic full-waveform data

    NARCIS (Netherlands)

    Abubakar, A.; Hu, W.; Habashy, T.M.; Van den Berg, P.M.

    2009-01-01

    We have applied the finite-difference contrast-source inversion (FDCSI) method to seismic full-waveform inversion problems. The FDCSI method is an iterative nonlinear inversion algorithm. However, unlike the nonlinear conjugate gradient method and the Gauss-Newton method, FDCSI does not solve any

  9. Marine and land active-source seismic investigation of geothermal potential, tectonic structure, and earthquake hazards in Pyramid Lake, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Eisses, A.; Kell, A.; Kent, G. [UNR; Driscoll, N. [UCSD; Karlin, R.; Baskin, R. [USGS; Louie, J. [UNR; Pullammanappallil, S. [Optim

    2016-08-01

    Amy Eisses, Annie M. Kell, Graham Kent, Neal W. Driscoll, Robert E. Karlin, Robert L. Baskin, John N. Louie, Kenneth D. Smith, Sathish Pullammanappallil, 2011, Marine and land active-source seismic investigation of geothermal potential, tectonic structure, and earthquake hazards in Pyramid Lake, Nevada: presented at American Geophysical Union Fall Meeting, San Francisco, Dec. 5-9, abstract NS14A-08.

  10. Relative Seismic Source Scaling of North Korean Nuclear Explosions Utilizing Regional Data

    Science.gov (United States)

    Park, J.; Che, I.; Hayward, C.; Stump, B. W.

    2013-12-01

    The relative source scaling of the 2006, 2009, and 2013 North Korean nuclear explosions is assessed using a Mueller and Murphy (1971) source model based interpretation of regional seismic station spectral ratios. Analyzing the regional phases, Pn, Pg, Sn, and Lg, separately provides source model estimates. Data from the KSRS seismic array in South Korea, MDJ seismic station in China, and the seismo-acoustic arrays: BRDAR, CHNAR, and KSGAR, cooperatively operated by KIGAM and SMU were used. Spectral levels of the second test are 3-4 times more energetic than the first test at low frequencies and become more equal in the 6-9 Hz frequency band as a result of source corner frequency effects. The third explosion is approximately 3 times more energetic than the second test at long periods, and 7-10 times more energetic than the first. A grid search method is used to explore the range of acceptable source models for each explosion resulting in estimates of yield and depth. Explosions that occurred in 2009 and 2013 are analyzed first because they are near one another (~450 m). The search space spanned from 10 to 1010 m at 50 m intervals and from 1.0 to 15.0 kt at 0.5 kt intervals. Summary results from the range of acceptable models are presented in terms of depth and yield ratios for the third to second test. The range of acceptable depth ratios for a goodness-of-fit (GOF) value of less than 10 was from 0.6-2.0 for Pn, 0.6-1.5 for Pg and 0.5-1.3 for both Sn and Lg. The best value (BV), with the smallest GOF, for depth ratios were approximately 1.0 for Pn, 0.9 for Pg, and 0.8 for Sn and Lg. The range estimates for the yield ratios were 2.2-4.0 (BV of 2.7) for Pn, 2.0-3.8 (BV of 2.3) for Pg, and 2.0-3.8 (BV of 2.6) for Sn and Lg. In the case of 2009/2006 explosions, the depth ratios are 0.5-2.8 (BV of 1.2) for Pn and 0.8 - 1.8 (BV of 1.1) for Pg, and the yield ratios are 3.0-6.0 (BV of 4.2) for Pn and 3.3-5.0 (BV of 4.0) for Pg, consistent with result by Kim et al. (2009

  11. Penetration characteristics of electromagnetic emissions from an underground seismic source into the atmosphere, ionosphere, and magnetosphere

    Science.gov (United States)

    Molchanov, O. A.; Hayakawa, M.; Rafalsky, V. A.

    1995-02-01

    Theoretical calculations are made on electromagnetic fields in the frequency range 10(exp -2) to 10(exp 2) Hz on the ground surface and above the ionosphere induced by stochastic microcurrent activity inside the future seismic sources on the assumption of cylindrical symmetry of the effective current and three types of polarization. The inhomogeneity of the ground and atmosphere conductivity and anisotropy of the ionosphere are taken into consideration. The intensity of ULF magnetic and electric precursors observed on the ground, and their spatial distribution can be explained by using the results of the present computations. It is found that only the fields from a magnetic type source can penetrate into the magnetosphere and generate propagating Alfven waves. The expected values of magnetospheric electric and magnetic field are 1-10 microV/m/square root of Hz and 1-10 pT/square root of Hz respectively, and the horizontal scale of their distribution is about 100-200 km. Finally, these theoretical predictions are compared with the corresponding results of satellite observations.

  12. Bolide Airbursts as a Seismic Source for the 2018 Mars InSight Mission

    Science.gov (United States)

    Stevanović, J.; Teanby, N. A.; Wookey, J.; Selby, N.; Daubar, I. J.; Vaubaillon, J.; Garcia, R.

    2017-10-01

    In 2018, NASA will launch InSight, a single-station suite of geophysical instruments, designed to characterise the martian interior. We investigate the seismo-acoustic signal generated by a bolide entering the martian atmosphere and exploding in a terminal airburst, and assess this phenomenon as a potential observable for the SEIS seismic payload. Terrestrial analogue data from four recent events are used to identify diagnostic airburst characteristics in both the time and frequency domain. In order to estimate a potential number of detectable events for InSight, we first model the impactor source population from observations made on the Earth, scaled for planetary radius, entry velocity and source density. We go on to calculate a range of potential airbursts from the larger incident impactor population. We estimate there to be {˜} 1000 events of this nature per year on Mars. To then derive a detectable number of airbursts for InSight, we scale this number according to atmospheric attenuation, air-to-ground coupling inefficiencies and by instrument capability for SEIS. We predict between 10-200 detectable events per year for InSight.

  13. Software Toolbox Development for Rapid Earthquake Source Optimisation Combining InSAR Data and Seismic Waveforms

    Science.gov (United States)

    Isken, Marius P.; Sudhaus, Henriette; Heimann, Sebastian; Steinberg, Andreas; Bathke, Hannes M.

    2017-04-01

    We present a modular open-source software framework (pyrocko, kite, grond; http://pyrocko.org) for rapid InSAR data post-processing and modelling of tectonic and volcanic displacement fields derived from satellite data. Our aim is to ease and streamline the joint optimisation of earthquake observations from InSAR and GPS data together with seismological waveforms for an improved estimation of the ruptures' parameters. Through this approach we can provide finite models of earthquake ruptures and therefore contribute to a timely and better understanding of earthquake kinematics. The new kite module enables a fast processing of unwrapped InSAR scenes for source modelling: the spatial sub-sampling and data error/noise estimation for the interferogram is evaluated automatically and interactively. The rupture's near-field surface displacement data are then combined with seismic far-field waveforms and jointly modelled using the pyrocko.gf framwork, which allows for fast forward modelling based on pre-calculated elastodynamic and elastostatic Green's functions. Lastly the grond module supplies a bootstrap-based probabilistic (Monte Carlo) joint optimisation to estimate the parameters and uncertainties of a finite-source earthquake rupture model. We describe the developed and applied methods as an effort to establish a semi-automatic processing and modelling chain. The framework is applied to Sentinel-1 data from the 2016 Central Italy earthquake sequence, where we present the earthquake mechanism and rupture model from which we derive regions of increased coulomb stress. The open source software framework is developed at GFZ Potsdam and at the University of Kiel, Germany, it is written in Python and C programming languages. The toolbox architecture is modular and independent, and can be utilized flexibly for a variety of geophysical problems. This work is conducted within the BridGeS project (http://www.bridges.uni-kiel.de) funded by the German Research Foundation DFG

  14. Structural Calculations of Drip Shield Exposed to Vibratory Ground Motion

    Energy Technology Data Exchange (ETDEWEB)

    S. Mastilovic

    2003-06-16

    The objective of this calculation is twofold. First, to determine whether or not separation of interlocking drip shield (DS) segments occurs during vibratory ground motion. Second, if DS separation does not occur, to estimate the area of the DS for which the residual 1st principal stress exceeds a certain limit. (The area of DS plate-1 and DS plate-2 [see Attachment I] where the residual 1st principal stress exceeds a certain limit will be, for brevity, referred to as ''the damaged area'' throughout this document; also, DS plate-1 and DS plate-2 will be referred to, for brevity, as ''DS plates'' henceforth.) The stress limit used throughout this document is defined as 50 percent of yield strength of the DS plate material, Titanium Grade 7 (Ti-7) (SB-265 R52400), at temperature of 150 C. A set of 15 calculations is performed at two different annual frequencies of occurrence (annual exceedance frequency): 10{sup -6} per year (1/yr) and 10{sup -7} 1/yr . (Note: Due to computational problems only five realizations at 10{sup -7} 1/yr are presented in this document.) Additionally, one calculation is performed at the annual frequency of occurrence of 5 {center_dot} 10{sup -4} 1/yr. The scope of this document is limited to reporting whether or not the DS separation occurs. If the DS separation does not occur the scope is limited to reporting the calculation results in terms of the damaged area. All these results are evaluated for the DS plates. This calculation is intended for use in support of the Total System Performance Assessment-License Application seismicity modeling. This calculation is associated with the DS design and was performed by the Waste Package Design group. AP-3.12Q, ''Design Calculations and Analyses'' (Ref. 1) is used to perform the calculation and develop the document. The DS is classified as Quality Level 1 (Ref. 5, p. 7). Therefore, this calculation is subject to the Quality Assurance

  15. Effects of ejaculation by penile vibratory stimulation on bladder capacity in men with spinal cord lesions

    DEFF Research Database (Denmark)

    Laessøe, Line; Sønksen, Jens; Bagi, Per

    2003-01-01

    We examined the effects of ejaculation by penile vibratory stimulation on bladder capacity in men with spinal cord lesions.......We examined the effects of ejaculation by penile vibratory stimulation on bladder capacity in men with spinal cord lesions....

  16. EXPERIMENTAL MODELLING OF MECHANISMS CAUSING OCCURRENCE OF SEISMIC OSCILLATION SOURCES IN CASE OF INTERACTIONS OF UNEVEN SURFACES IN FAULTS

    Directory of Open Access Journals (Sweden)

    V. V. Ruzhich

    2014-01-01

    Full Text Available Field experiments were carried out using TRIBO, a specially designed testing stand including a concrete plate that can be moved at different rates. In our experiment, the plate served as an artificial allochtonous wing placed at the uneven surface of the segment of the Angarsky fault in Pribaikalie. Tribological effects of contact interaction of the uneven surfaces in the zone of sliding movements of the plate were recorded by strain gauges, linear displacement gauges and four Baikal-7HR seismic stations; such stations are commonly used for earthquake recording. The effect of shocks in initiation of seismic oscillation sources was studied with changes of the regimes of destruction of the uneven surfaces (underneath the base of the plate which differ in size and strength. The study was focused on stages in the process of friction at preparation to transition from quasi-regular decelerated sliding movement of the plate to its breakaway and occurrence of a high-energy seismic impulse.The applied method of large-scale modelling at natural objects in field provides new data that may prove useful for stu­dies of mechanisms causing seismicity, identification of stages in occurrence of earthquakes in fault zones and interpretation of seismic monitoring data. Results of such physical tests can contribute to the development of methods aimed at forecasting of rock shocks and earthquakes and also for the development of new physical models showing formation of earthquake foci of various scales in tectonic faults.

  17. A Three-Dimensional Seismic Model of the Dead Sea Plate Boundary From Active Source Data

    Science.gov (United States)

    Flores, C. H.; ten Brink, U. S.

    2007-12-01

    The Dead Sea fault system is a north-south striking left-lateral shear zone separating the African and Arabian tectonic plates. The southern part of the plate boundary is located within the Dead Sea valley. The valley, much of it below sea level, is surrounded by highlands on both sides, and contains subsurface sedimentary basins, including the large (~150 km long) a deep (6-8 km) Dead Sea basin. A wide-angle seismic reflection and refraction experiment was carried out in the Dead Sea Region in October 2004 to study the deep structure of the plate boundary. The experiment consisted of two perpendicular profiles a 280-km long profile along the valley and the international border between Jordan, Israel and the Palestinian Territories, and a 250 km long profile from Gaza strip to eastern Jordan across the Dead Sea basin. Modeling of the West-East line shows a low velocity zone extending to a depth of 18 km below the basin, which includes >6 km of "syn-rift" sediments (ten Brink et al., GRL, 2006). The lower crust and Moho are not perturbed. The uplift surrounding the Dead Sea Transform also appears to be an upper crustal phenomenon. The shear deformation, associated with the transform plate boundary motion appears, on the other hand, to cut throughout the entire crust (Ibid.). Two-dimensional modeling of the South-North line is more complex due to the fact that sedimentary basins do not occupy the entire width of the valley hence some sources and some receivers are located within the basins whereas others are located outside. This heterogeneous near-surface structure explains why a simple 2-D velocity model does not fit the observed travel times from all shots. Therefore, we are using 3-D travel-time tomography to model the heterogeneous near-surface and deeper structure of the Dead Sea. Preliminary models indicate that some ray-paths from sources near the basin use the edges of the basin as a wave-guide and generate earlier than expected arrivals at receivers near

  18. Using a Large N Geophone Array to Identify Hydrothermal Seismic Sources in the Upper Geyser Basin of Yellowstone National Park

    Science.gov (United States)

    Farrell, J.; Lin, F. C.; Allam, A. A.; Smith, R. B.; Karplus, M. S.

    2016-12-01

    The recent availability of large N seismic arrays provides a unique capability for recording environmental seismic signals that can be monitored in detail. In November 2015, the University of Utah, in collaboration with Yellowstone National Park and the University of Texas El Paso, installed a seismic array in the Upper Geyser Basin of Yellowstone National Park centered on Old Faithful geyser. The array consisted of 133 three-component 5 Hz geophones recording continuously at 1000Hz for two weeks, with an average station spacing of 50 m and an aperture of 1 km. The array recorded numerous hydrothermal seismic sources including distinct seismic signals that could be attributed to surficial hydrothermal features as well as those that do not appear to be related to any individual surface feature. Old Faithful geyser eruptions themselves are largely aseismic. However, hydrothermal tremor, likely due to collapsing bubbles within the subsurface plumbing system, starts building about 45 minutes prior to an Old Faithful eruption. Tremor amplitudes slowly increase with time until they reach a peak about 25 minutes prior to the eruption and then slowly decrease until the eruption begins. The seismic signal related to the buildup of the Old Faithful subsurface reservoir is recorded at stations north, south and to the east of Old Faithful but is missing on stations to the northwest. This suggests a shallow subsurface feature that strongly attenuates the seismic signal immediately NW of the cone of Old Faithful. Another of the more interesting signals is observed regularly about every 38 minutes and may come from Doublet Pool on Geyser Hill. This signal has large seismic wave amplitudes and is recorded across much of the seismic array. The Geyser Hill signal may also be affected by the aforementioned subsurface attenuating feature NW of the Old Faithful cone. Interestingly, there is a persistent 20-25 Hz signal at several stations that seems to be affected by variations air

  19. Probabilistic tsunami hazard in the North East Atlantic due to seismic sources, implications for NEAMTWS

    Science.gov (United States)

    Omira, R.; Baptista, M.; Matias, L. M.; Miranda, J. M.; Carrilho, F.

    2013-12-01

    Recently, several studies on tsunami hazard assessment for the North East Atlantic coasts have been published. These studies use deterministic approach based upon the most credible earthquake scenario and/or the worst case scenario to derive tsunami coastal hazard in terms of wave elevation and inundation maps. In this work, we present the first thorough study on probabilistic tsunami hazard assessment due to earthquake sources for the North East Atlantic area. We consider three main seismogenic areas: the Gulf of Cadiz, the Gloria Fault and the Caribbean arc. For each seismogenic zone we derive the annual recurrence rate for each magnitude range, starting from Mw7.5 to Mw9.0, using the Bayesian method that incorporates seismic information from historical catalog and instrumental periods. A numerical code, solving the linear shallow water equations is employed to simulate the tsunami propagation and compute near shore wave heights along the entire NE Atlantic coast and at the forecast points of the NEAMTWS. To establish, for multiple sources, the joint probability that wave height exceeds a particular value for a given time period, we consider that the sources are independent (like in the Poison distribution). This process allows calculating the time-independent probability that wave height, simulated by numerical code, will be exceeded due to the occurrence of a tsunami source with a known average rate, derived from sources' recurrence assessment, during a period of time. The results are presented in terms of the probability of exceedance of a given tsunami amplitude for 100, 500 and 1000 years, and hazard curves for selected forecast points of the NEAMTWS countries. The level of hazard varies along the coast being maximum along the northern segment of the Morocco Atlantic coast, the southern Portuguese coast and the Spanish coast of the Gulf of Cadiz. The results show that the probability of a tsunami wave exceeding 1 m in the next 500 years reaches 100% in some

  20. Seismic source characterization of the Alpine foreland in the context of a probabilistic seismic hazard analysis by PEGASOS Expert Group 1 (EG1a)

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, S. M. [Geologisch-Palaeontologisches Institut, University of Basel, Basel (Switzerland); Slejko, D. [Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Trieste (Italy)

    2009-05-15

    Seismic source characterization is performed as part of the PEGASOS project for the assessment of the seismic hazard at the 4 sites of the Swiss Nuclear Power Plants. The analysis is performed according to the Level 4 procedures for expert elicitation defined in the guidelines of the US Nuclear Regulatory Committee whereby the quantification of uncertainties plays a crucial role. According to our analysis, which is one amongst four that were performed in the frame of PEGASOS, the most important epistemic uncertainty is related to the question as to whether basement-rooted faults at the margins of pre-existing Permo-Carboniferous troughs are prone for compressive or transpressive reactivation under the present-day stress field or not. The question after the present-day style of deformation in the Alpine foreland (thick-skinned versus thin-skinned) is closely related to this key question. Together with the consideration of uncertainties regarding the mapping of seismogenic zones and/or line sources, alternative zonations are presented in form of a logic tree with 21 branches. Area sources play a predominant role in the working area located at the margin of a diffuse plate boundary. Earthquake recurrence relationships are discussed by taking into account a series of uncertainties. These concern the evaluation of b-values and the evaluation of a-values once the b-values were fixed. Both parameters in the Gutenberg-Richter law are based on non-perfect and incomplete catalogue data that were carefully analysed beforehand. Since PEGASOS demanded an analysis of annual probabilities down to one event in 10{sup 7} years, the question after the value of the maximum possible earthquake magnitude M{sub max} and related error in M{sub max} estimates plays a crucial role. We estimate M{sub max} by using geological as well as statistical methods. M{sub max} = 6.9 cannot be excluded in most areas, in the Basel area M{sub max} = 7.3 is possible. Uncertainties in a, b and M{sub max

  1. A subharmonic vibratory pattern in normal vocal folds

    NARCIS (Netherlands)

    Svec, JG; Schutte, HK; Miller, DG

    This study observes in detail an F-0/2 (sounding an octave below an original tone) subharmonic vibratory pattern produced in a normal larynx. Simultaneous electroglottographic and photoglottographic measurements reveal two different open phases within a subharmonic cycle-the first shorter with a

  2. Automation Selection and Sequencing of Traps for Vibratory Feeders

    DEFF Research Database (Denmark)

    Mathiesen, Simon; Ellekilde, Lars-Peter

    2017-01-01

    Vibratory parts feeders with mechanical orienting devices are used extensively in the assembly automation industry. Even so, the design process is based on trial-and-error approaches and is largely manual. In this paper, a methodology is presented for automatic design of this type of feeder...

  3. Constraints on Faulting and Basin Architecture in the North Basin of Lake Malawi from Active-Source Seismic Data

    Science.gov (United States)

    Onyango, E. A.; Shillington, D. J.; Accardo, N. J.; Scholz, C. A.; Ebinger, C. J.; Gaherty, J. B.; McCartney, T.; Nyblade, A.; Chindandali, P. R. N.; Kamihanda, G.; Ferdinand, R.; Salima, J.; Mruma, A. H.

    2016-12-01

    The East African Rift System (EARS) is actively extending as evidenced by seismicity and volcanic activity, and it is a great example of continental rifting. The western branch of the EARS consists of a series of rift basins bound by 100-km-long border faults, with Lake Malawi being the southernmost. Previous studies on Lake Malawi suggest that the border faults accommodate most of the crustal extension and account for most of the seismicity. However, the 2009 Karonga earthquake sequence and other seismicity on intrabasinal faults suggest that they may also be important for crustal extension and hazards. This study uses seismic reflection and wide-angle refraction data from the Study of Extension and maGmatism in Malawi and Tanzania (SEGMeNT) experiment to constrain detailed basin architecture, shallow velocities, and fault structures of the North Basin of the Malawi Rift. We present results from the main reflection/refraction dip line across the North Basin. Seven lake bottom seismometers (LBS) were spaced at 7 km and recorded shots from a 2580 cu in air gun array fired every 250 m. We recorded multichannel seismic data (MCS) along the same line with a 1500-m-long streamer and a source of 1540 cu in fired every 37.5 m. The LBS also recorded the small volume shots along this line. We picked sedimentary and crustal refractions and reflections using recordings from both shot volumes. We used the First Arrival Seismic Tomography (FAST) code to obtain a smooth velocity model using the first arrivals, and iterative forward modeling was done using the RAYINVR code to produce layered model using both first and later arrivals. Concurrently, the coincident seismic reflection profile was processed using the SeisSpace software package. Preliminary results show sediments in the North basin are thickening Eastward, reaching a thickness of over 4 km adjacent to the Livingstone border fault. Sediments have velocities of 2-3 km/s. The largest intra-basin fault has a substantial

  4. Investigation of model based beamforming and Bayesian inversion signal processing methods for seismic localization of underground sources

    DEFF Research Database (Denmark)

    Oh, Geok Lian; Brunskog, Jonas

    2014-01-01

    Techniques have been studied for the localization of an underground source with seismic interrogation signals. Much of the work has involved defining either a P-wave acoustic model or a dispersive surface wave model to the received signal and applying the time-delay processing technique and frequ...... that for field data, inversion for localization is most advantageous when the forward model completely describe all the elastic wave components as is the case of the FDTD 3D elastic model....

  5. Site Characterization of the Source Physics Experiment Phase II Location Using Seismic Reflection Data

    Science.gov (United States)

    Sexton, E. A.; Snelson, C. M.; Chipman, V.; Emer, D. F.; White, R. L.; Emmitt, R.; Wright, A. A.; Drellack, S.; Huckins-Gang, H.; Mercadante, J.; Floyd, M.; McGowin, C.; Cothrun, C.; Bonal, N.

    2013-12-01

    An objective of the Source Physics Experiment (SPE) is to identify low-yield nuclear explosions from a regional distance. Low-yield nuclear explosions can often be difficult to discriminate among the clutter of natural and man-made explosive events (e.g., earthquakes and mine blasts). The SPE is broken into three phases. Phase I has provided the first of the physics-based data to test the empirical models that have been used to discriminate nuclear events. The Phase I series of tests were placed within a highly fractured granite body. The evolution of the project has led to development of Phase II, to be placed within the opposite end member of geology, an alluvium environment, thereby increasing the database of waveforms to build upon in the discrimination models. Both the granite and alluvium sites have hosted nearby nuclear tests, which provide comparisons for the chemical test data. Phase III of the SPE is yet to be determined. For Phase II of the experiment, characterization of the location is required to develop the geologic/geophysical models for the execution of the experiment. Criteria for the location are alluvium thickness of approximately 170 m and a water table below 170 m; minimal fracturing would be ideal. A P-wave mini-vibroseis survey was conducted at a potential site in alluvium to map out the subsurface geology. The seismic reflection profile consisted of 168 geophone stations, spaced 5 m apart. The mini-vibe was a 7,000-lb peak-force source, starting 57.5 m off the north end of the profile and ending 57.5 m past the southern-most geophone. The length of the profile was 835 m. The source points were placed every 5 m, equally spaced between geophones to reduce clipping. The vibroseis sweep was from 20 Hz down to 180 Hz over 8 seconds, and four sweeps were stacked at each shot location. The shot gathers show high signal-to-noise ratios with clear first arrivals across the entire spread and the suggestion of some shallow reflectors. The data were

  6. Investigation of model based beamforming and Bayesian inversion signal processing methods for seismic localization of underground sources.

    Science.gov (United States)

    Oh, Geok Lian; Brunskog, Jonas

    2014-08-01

    Techniques have been studied for the localization of an underground source with seismic interrogation signals. Much of the work has involved defining either a P-wave acoustic model or a dispersive surface wave model to the received signal and applying the time-delay processing technique and frequency-wavenumber processing to determine the location of the underground tunnel. Considering the case of determining the location of an underground tunnel, this paper proposed two physical models, the acoustic approximation ray tracing model and the finite difference time domain three-dimensional (3D) elastic wave model to represent the received seismic signal. Two localization algorithms, beamforming and Bayesian inversion, are developed for each physical model. The beam-forming algorithms implemented are the modified time-and-delay beamformer and the F-K beamformer. Inversion is posed as an optimization problem to estimate the unknown position variable using the described physical forward models. The proposed four methodologies are demonstrated and compared using seismic signals recorded by geophones set up on ground surface generated by a surface seismic excitation. The examples show that for field data, inversion for localization is most advantageous when the forward model completely describe all the elastic wave components as is the case of the FDTD 3D elastic model.

  7. Scalable Metadata Management for a Large Multi-Source Seismic Data Repository

    Energy Technology Data Exchange (ETDEWEB)

    Gaylord, J. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dodge, D. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Magana-Zook, S. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Barno, J. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Knapp, D. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Thomas, J. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Sullivan, D. S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ruppert, S. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mellors, R. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-05-26

    In this work, we implemented the key metadata management components of a scalable seismic data ingestion framework to address limitations in our existing system, and to position it for anticipated growth in volume and complexity.

  8. Extended sources of the main events of the Umbria-Marche (1997 seismic sequence inverted from geophysical data

    Directory of Open Access Journals (Sweden)

    M. E. Belardinelli

    2008-06-01

    Full Text Available The three largest events of the 1997 Umbria-Marche (Italy sequence occurred on September 26, 1997 at 00:33 GMT (Event 1, MW=5.7 and 09:40 GMT (Event 2, MW=6.0 in the Colfiorito area and on the October 14, 1997 at 15:23 (Event 3, MW=5.6 in the Sellano area. The availability of different sets of geodetic and seismological data allowed several studies to characterize the extended sources of events 1-3. In this work, I review some of the studies that obtain the properties of the seismic sources by inversion of available data. Generally these studies assume the seismic sources as dislocations or distributions of equivalent point sources in elastic half-spaces. Following their chronological order, they model increasing complexities of the sources by using an increasing number of data. Some of the differences between results obtained, such as the top edge depth estimates, are shown to be due to the different approaches used. Commonly a 1-D crustal model is used in inverting strongmotion data. Instead homogeneous elastic half-spaces are mainly assumed in inverting geodetic data to obtain the three main sources of the 1997 Umbria-Marche sequence. Assuming the same crustal structure is important to make comparable results obtained analyzing seismological data or geodetic data separately, as it has been done till now for this sequence.

  9. Probabilistic tsunami hazard assessment in Greece for seismic sources along the segmented Hellenic Arc

    Science.gov (United States)

    Novikova, Tatyana; Babeyko, Andrey; Papadopoulos, Gerassimos

    2017-04-01

    Greece and adjacent coastal areas are characterized by a high population exposure to tsunami hazard. The Hellenic Arc is the most active geotectonic structure for the generation of earthquakes and tsunamis. We performed probabilistic tsunami hazard assessment for selected locations of Greek coastlines which are the forecasting points officially used in the tsunami warning operations by the Hellenic National Tsunami Warning Center and the NEAMTWS/IOC/UNESCO. In our analysis we considered seismic sources for tsunami generation along the western, central and eastern segments of the Hellenic Arc. We first created a synthetic catalog as long as 10,000 years for all the significant earthquakes with magnitudes in the range from 6.0 to 8.5, the real events being included in this catalog. For each event included in the synthetic catalog a tsunami was generated and propagated using Boussinesq model. The probability of occurrence for each event was determined by Gutenberg-Richter magnitude-frequency distribution. The results of our study are expressed as hazard curves and hazard maps. The hazard curves were obtained for the selected sites and present the annual probability of exceedance as a function of pick coastal tsunami amplitude. Hazard maps represent the distribution of peak coastal tsunami amplitudes corresponding to a fixed annual probability. In such forms our results can be easily compared to the ones obtained in other studies and further employed for the development of tsunami risk management plans. This research is a contribution to the EU-FP7 tsunami research project ASTARTE (Assessment, Strategy And Risk Reduction for Tsunamis in Europe), grant agreement no: 603839, 2013-10-30.

  10. Developing and exploiting a unique seismic dataset from South African gold mines for source characterization and wave propagation

    CSIR Research Space (South Africa)

    Julia

    2008-09-01

    Full Text Available stream_source_info Julia_2008.pdf.txt stream_content_type text/plain stream_size 28067 Content-Encoding UTF-8 stream_name Julia_2008.pdf.txt Content-Type text/plain; charset=UTF-8 DEVELOPING AND EXPLOITING A UNIQUE... SEISMIC DATASET FROM SOUTH AFRICAN GOLD MINES FOR SOURCE CHARACTERIZATION AND WAVE PROPAGATION Jordi Julià1, Andrew A. Nyblade1, Rengin Gök2, William R. Walter2, Lindsay Linzer3, and Ray Durrheim3 Penn State University1, Lawrence Livermore National...

  11. Fundamental understanding, prediction and validation of rotor vibratory loads in steady-level flight

    Science.gov (United States)

    Datta, Anubhav

    This work isolates the physics of aerodynamics and structural dynamics from the helicopter rotor aeromechanics problem, investigates them separately, identifies the prediction deficiencies in each, improves upon them, and couples them back together. The objective is to develop a comprehensive analysis capability for accurate and consistent prediction of rotor vibratory loads in steady level flight. The rotor vibratory loads are the dominant source of helicopter vibration. There are two critical vibration regimes for helicopters in steady level flight: (1) low speed transition and (2) high speed forward flight. The mechanism of rotor vibration at low speed transition is well understood---inter-twinning of blade tip vortices below the rotor disk. The mechanism of rotor vibration at high speed is not clear. The focus in this research is on high speed flight. The goal is to understand the key mechanisms involved and accurately model them. Measured lift, chord force, pitching moment and damper force from the UH-60A Flight Test Program are used to predict, validate and refine the rotor structural dynamics. The prediction errors originate entirely from structural modeling. Once validated, the resultant blade deformations are used to predict and validate aerodynamics. Air loads are calculated using a table look up based unsteady lifting-line model and compared with predictions from a 3-dimensional unsteady CFD model. Both Navier-Stokes and Euler predictions are studied. (Abstract shortened by UMI.) The 3D Navier-Stokes CFD analysis is then consistently coupled with a rotor comprehensive analysis to improve prediction of rotor vibratory loads at high speed. The CFD-comprehensive code coupling is achieved using a loose coupling methodology. The CFD analysis significantly improves section pitching moment prediction near the blade tip, because it captures the steady and unsteady 3D transonic effects. Accurate pitching moments drive elastic twist deformations which together

  12. Seismic source associated with the repetitive events recorded at the Nevado del Huila volcano - Colombia in November 2008

    Science.gov (United States)

    Trujillo, N.; Valdes-González, C. M.; White, R.; Dawson, P. B.; McCausland, W. A.; Santacoloma, C.

    2016-12-01

    The Nevado del Huila Volcano recorded an eruption on November 21st, 2008. This eruptive event was preceded by approximately 11,200 seismic events associated to fluids dynamic inside volcanic conduits. These seismic signals were classified as Hybrid events (HB), Long Period events (LP) and Drumbeat events, and they presented as fundamental characteristic, great regularity in the time, i. e. their waveforms and their bandwidths were very similar to each other. Cardona et al. (2009) made a first analysis of these signals and proposed the existence of two seismic families: the first integrated by LP events and HB events registered in the period, November 9th to November 21st; and second family composed by the Drumbeats events registered between November 20th and 21st. Our project took as starting point the work of Cardona et al. (2009); we establish the degree of similarity between events of each of the two families proposed by Cardona et al. (2009). First, we made a temporal analysis by using the Hilbert Transform, and then applied the cross-correlation technique. Finally a stacking of the signals with correlation coefficients > 0.9, was obtained. The results were: 8000 events with correlation coefficients > 0.9 and the existence of six possible seismic families. A detailed analysis of the seismic signals obtained through the stacking allowed us to conclude the existence of four families, the first one recorded between the 4th to 18th of November, the second one for the drumbeat events recorded on November 11th, the third one for the seismicity recorded between the 14th and 21st of November, and the four one for the drumbeat events registered on November 20th and 21st. We suggest that each of these families was associated with a different seismic source; so, the first and third families were possibly associated to mechanisms like brittle fracturing that can occur in weak areas where cracks or conduits intersect, and where acoustic resonance can occur, and the second

  13. Tsunami hazard maps of spanish coast at national scale from seismic sources

    Science.gov (United States)

    Aniel-Quiroga, Íñigo; González, Mauricio; Álvarez-Gómez, José Antonio; García, Pablo

    2017-04-01

    Tsunamis are a moderately frequent phenomenon in the NEAM (North East Atlantic and Mediterranean) region, and consequently in Spain, as historic and recent events have affected this area. I.e., the 1755 earthquake and tsunami affected the Spanish Atlantic coasts of Huelva and Cadiz and the 2003 Boumerdés earthquake triggered a tsunami that reached Balearic island coast in less than 45 minutes. The risk in Spain is real and, its population and tourism rate makes it vulnerable to this kind of catastrophic events. The Indian Ocean tsunami in 2004 and the tsunami in Japan in 2011 launched the worldwide development and application of tsunami risk reduction measures that have been taken as a priority in this field. On November 20th 2015 the directive of the Spanish civil protection agency on planning under the emergency of tsunami was presented. As part of the Spanish National Security strategy, this document specifies the structure of the action plans at different levels: National, regional and local. In this sense, the first step is the proper evaluation of the tsunami hazard at National scale. This work deals with the assessment of the tsunami hazard in Spain, by means of numerical simulations, focused on the elaboration of tsunami hazard maps at National scale. To get this, following a deterministic approach, the seismic structures whose earthquakes could generate the worst tsunamis affecting the coast of Spain have been compiled and characterized. These worst sources have been propagated numerically along a reconstructed bathymetry, built from the best resolution available data. This high-resolution bathymetry was joined with a 25-m resolution DTM, to generate continuous offshore-onshore space, allowing the calculation of the flooded areas prompted by each selected source. The numerical model applied for the calculation of the tsunami propagations was COMCOT. The maps resulting from the numerical simulations show not only the tsunami amplitude at coastal areas but

  14. Sources of Error and the Statistical Formulation of M S: m b Seismic Event Screening Analysis

    Science.gov (United States)

    Anderson, D. N.; Patton, H. J.; Taylor, S. R.; Bonner, J. L.; Selby, N. D.

    2014-03-01

    The Comprehensive Nuclear-Test-Ban Treaty (CTBT), a global ban on nuclear explosions, is currently in a ratification phase. Under the CTBT, an International Monitoring System (IMS) of seismic, hydroacoustic, infrasonic and radionuclide sensors is operational, and the data from the IMS is analysed by the International Data Centre (IDC). The IDC provides CTBT signatories basic seismic event parameters and a screening analysis indicating whether an event exhibits explosion characteristics (for example, shallow depth). An important component of the screening analysis is a statistical test of the null hypothesis H 0: explosion characteristics using empirical measurements of seismic energy (magnitudes). The established magnitude used for event size is the body-wave magnitude (denoted m b) computed from the initial segment of a seismic waveform. IDC screening analysis is applied to events with m b greater than 3.5. The Rayleigh wave magnitude (denoted M S) is a measure of later arriving surface wave energy. Magnitudes are measurements of seismic energy that include adjustments (physical correction model) for path and distance effects between event and station. Relative to m b, earthquakes generally have a larger M S magnitude than explosions. This article proposes a hypothesis test (screening analysis) using M S and m b that expressly accounts for physical correction model inadequacy in the standard error of the test statistic. With this hypothesis test formulation, the 2009 Democratic Peoples Republic of Korea announced nuclear weapon test fails to reject the null hypothesis H 0: explosion characteristics.

  15. Fast 3D elastic micro-seismic source location using new GPU features

    Science.gov (United States)

    Xue, Qingfeng; Wang, Yibo; Chang, Xu

    2016-12-01

    In this paper, we describe new GPU features and their applications in passive seismic - micro-seismic location. Locating micro-seismic events is quite important in seismic exploration, especially when searching for unconventional oil and gas resources. Different from the traditional ray-based methods, the wave equation method, such as the method we use in our paper, has a remarkable advantage in adapting to low signal-to-noise ratio conditions and does not need a person to select the data. However, because it has a conspicuous deficiency due to its computation cost, these methods are not widely used in industrial fields. To make the method useful, we implement imaging-like wave equation micro-seismic location in a 3D elastic media and use GPU to accelerate our algorithm. We also introduce some new GPU features into the implementation to solve the data transfer and GPU utilization problems. Numerical and field data experiments show that our method can achieve a more than 30% performance improvement in GPU implementation just by using these new features.

  16. Imaging a Fault Boundary System Using Controlled-Source Data Recorded on a Large-N Seismic Array

    Science.gov (United States)

    Paschall, O. C.; Chen, T.; Snelson, C. M.; Ralston, M. D.; Rowe, C. A.

    2016-12-01

    The Source Physics Experiment (SPE) is a series of chemical explosions conducted in southern Nevada with an objective of improving nuclear explosion monitoring. Five chemical explosions have occurred thus far in granite, the most recent being SPE-5 on April 26, 2016. The SPE series will improve our understanding of seismic wave propagation (primarily S-waves) due to explosions, and allow better discrimination of background seismicity such as earthquakes and explosions. The Large-N portion of the project consists of 996 receiver stations. Half of the stations were vertical component and the other half were three-component geophones. All receivers were deployed for 30 days and recorded the SPE-5 shot, earthquakes, noise, and an additional controlled-source: a large weight-drop, which is a 13,000 kg modified industrial pile driver. In this study, we undertake reflection processing of waveforms from the weight-drop, as recorded by a line of sensors extracted from the Large-N array. The profile is 1.2 km in length with 25 m station spacing and 100 m shot point spacing. This profile crosses the Boundary Fault that separates granite body and an alluvium basin, a strong acoustic impedance boundary that scatters seismic energy into S-waves and coda. The data were processed with traditional seismic reflection processing methods that include filtering, deconvolution, and stacking. The stack will be used to extract the location of the splays of the Boundary Fault and provide geologic constraints to the modeling and simulation teams within the SPE project.

  17. The PROTEUS Experiment: Active Source Seismic Imaging of the Crustal Magma Plumbing Structure of the Santorini Arc Volcano

    Science.gov (United States)

    Hooft, E. E. E.; Morgan, J. V.; Nomikou, P.; Toomey, D. R.; Papazachos, C. V.; Warner, M.; Heath, B.; Christopoulou, M. E.; Lampridou, D.; Kementzetzidou, D.

    2016-12-01

    The goal of the PROTEUS seismic experiment (Plumbing Reservoirs Of The Earth Under Santorini) is to examine the entire crustal magma plumbing system beneath a continental arc volcano and determine the magma geometry and connections throughout the crust. These physical parameters control magma migration, storage, and eruption and inform the question of how physical and chemical processing of magma at arc volcanoes forms the andesitic rock compositions that dominate the lower continental crust. These physical parameters are also important to understand volcanic-tectonic interactions and geohazards. Santorini is ideal for these goals because the continental crust has been thinned by extension and so the deep magmatic system is more accessible, also it is geologically well studied. Since the volcano is a semi-submerged, it was possible to collect a unique 3D marine-land active source seismic dataset. During the PROTEUS experiment in November-December of 2015, we recorded 14,300 marine sound sources from the US R/V Langseth on 89 OBSIP short period ocean bottom seismometers and 60 German and 5 Greek land seismometers. The experiment was designed for high-density spatial sampling of the seismic wavefield to allow us to apply two state-of-the-art 3D inversion methods: travel time tomography and full waveform inversion. A preliminary travel time tomography model of the upper crustal seismic velocity structure of the volcano and surrounding region is presented in an accompanying poster. We also made marine geophysical maps of the seafloor using multi-beam bathymetry and of the gravity and magnetic fields. The new seafloor map reveals the detailed structure of the major fault system between Santorini and Amorgos, of associated landslides, and of newly discovered volcanic features. The PROTEUS project will provide new insights into the structure of the whole crustal magmatic system of a continental arc volcano and its evolution within the surrounding tectonic setting.

  18. Shallow shear-wave reflection seismics in the tsunami struck Krueng Aceh River Basin, Sumatra

    Directory of Open Access Journals (Sweden)

    U. Polom

    2008-01-01

    Full Text Available As part of the project "Management of Georisk" (MANGEONAD of the Federal Institute for Geosciences and Natural Resources (BGR, Hanover, high resolution shallow shear-wave reflection seismics was applied in the Indonesian province Nanggroe Aceh Darussalam, North Sumatra in cooperation with the Government of Indonesia, local counterparts, and the Leibniz Institute for Applied Geosciences, Hanover. The investigations were expected to support classification of earthquake site effects for the reconstruction of buildings and infrastructure as well as for groundwater exploration. The study focussed on the city of Banda Aceh and the surroundings of Aceh Besar. The shear-wave seismic surveys were done parallel to standard geoengineering investigations like cone penetrometer tests to support subsequent site specific statistical calibration. They were also partly supplemented by shallow p-wave seismics for the identification of (a elastic subsurface parameters and (b zones with abundance of groundwater. Evaluation of seismic site effects based on shallow reflection seismics has in fact been found to be a highly useful method in Aceh province. In particular, use of a vibratory seismic source was essential for successful application of shear-wave seismics in the city of Banda Aceh and in areas with compacted ground like on farm tracks in the surroundings, presenting mostly agricultural land use areas. We thus were able to explore the mechanical stiffness of the subsurface down to 100 m depth, occasionally even deeper, with remarkably high resolution. The results were transferred into geotechnical site classification in terms of the International Building Code (IBC, 2003. The seismic images give also insights into the history of the basin sedimentation processes of the Krueng Aceh River delta, which is relevant for the exploration of new areas for construction of safe foundations of buildings and for identification of fresh water aquifers in the tsunami

  19. Characterization of the Bell-Shaped Vibratory Angular Rate Gyro

    Directory of Open Access Journals (Sweden)

    Junfang Fan

    2013-08-01

    Full Text Available The bell-shaped vibratory angular rate gyro (abbreviated as BVG is a novel shell vibratory gyroscope, which is inspired by the Chinese traditional bell. It sensitizes angular velocity through the standing wave precession effect. The bell-shaped resonator is a core component of the BVG and looks like the millimeter-grade Chinese traditional bell, such as QianLong Bell and Yongle Bell. It is made of Ni43CrTi, which is a constant modulus alloy. The exciting element, control element and detection element are uniformly distributed and attached to the resonator, respectively. This work presents the design, analysis and experimentation on the BVG. It is most important to analyze the vibratory character of the bell-shaped resonator. The strain equation, internal force and the resonator's equilibrium differential equation are derived in the orthogonal curvilinear coordinate system. When the input angular velocity is existent on the sensitive axis, an analysis of the vibratory character is performed using the theory of thin shells. On this basis, the mode shape function and the simplified second order normal vibration mode dynamical equation are obtained. The coriolis coupling relationship about the primary mode and secondary mode is established. The methods of the signal processing and control loop are presented. Analyzing the impact resistance property of the bell-shaped resonator, which is compared with other shell resonators using the Finite Element Method, demonstrates that BVG has the advantage of a better impact resistance property. A reasonable means of installation and a prototypal gyro are designed. The gyroscopic effect of the BVG is characterized through experiments. Experimental results show that the BVG has not only the advantages of low cost, low power, long work life, high sensitivity, and so on, but, also, of a simple structure and a better impact resistance property for low and medium angular velocity measurements.

  20. Comparing seismic parameters for different source zone models in the Iberian Peninsula

    Science.gov (United States)

    Amaro-Mellado, J. L.; Morales-Esteban, A.; Asencio-Cortés, G.; Martínez-Álvarez, F.

    2017-10-01

    Seismical parameters of five seismogenic zonings for the Iberian Peninsula have been determined in this work. For that purpose, this research has two key goals. The first is to generate a seismic catalog. The second to calculate the seismical parameters of all the zones of the seismogenic zonings selected. The first key goal has been the creation of a catalog of earthquakes for the Iberian Peninsula and adjacent areas. First, the National Geographic Institute of Spain's catalog has been completed and reviewed with the information from other catalog reviews and specific studies. Second, all magnitude calculations have been homogenized. Third, all dependent data have been eliminated through declustering. Finally, the year of completeness for each magnitude has been considered. The Quaternary active faults database of Iberia has also been used as input data. All of this information has been integrated into a geographic information system. The second key aim is the calculation of the seismical parameters. The first parameter obtained has been the b-value. A method which considers different years of completeness in accordance with the magnitude has been used. Also, the annual rate of earthquakes per square kilometer has been calculated. Moreover, the maximum magnitude known that Quaternary active faults might generate and maximum magnitude recorded in the catalog have been determined. Finally, based solely on the statistical parameters obtained, a critical discussion of the seismogenic zonings of the Iberian Peninsula has been conducted. The results show that some zonings possess insufficient data for a proper calculation of the seismic parameters, from a statistical point of view.

  1. Phenomenological description of seismic sources in a pre-stressed, self-gravitating, thermo-visco-elastic earth model

    Directory of Open Access Journals (Sweden)

    M. BONAFEDE

    1977-06-01

    Full Text Available SUMMARY - The equations of motion for a pre-stressed, self-gravitating,
    thermo-viscolastic Earth model undergoing a dislocation are solved through a
    normal mode expansion of the displacement field. The non-hermiticity of the
    involved convolution operator is shown not to allow the stress relaxation to be
    included in the model stress. Accordingly, the stress glut moment tensor cannot
    be assumed to be strictly localized within the seismic source region.

  2. Numerical Procedure to Forecast the Tsunami Parameters from a Database of Pre-Simulated Seismic Unit Sources

    Science.gov (United States)

    Jiménez, César; Carbonel, Carlos; Rojas, Joel

    2017-09-01

    We have implemented a numerical procedure to forecast the parameters of a tsunami, such as the arrival time of the front of the first wave and the maximum wave height in real and virtual tidal stations along the Peruvian coast, with this purpose a database of pre-computed synthetic tsunami waveforms (or Green functions) was obtained from numerical simulation of seismic unit sources (dimension: 50 × 50 km2) for subduction zones from southern Chile to northern Mexico. A bathymetry resolution of 30 arc-sec (approximately 927 m) was used. The resulting tsunami waveform is obtained from the superposition of synthetic waveforms corresponding to several seismic unit sources contained within the tsunami source geometry. The numerical procedure was applied to the Chilean tsunami of April 1, 2014. The results show a very good correlation for stations with wave amplitude greater than 1 m, in the case of the Arica tide station an error (from the maximum height of the observed and simulated waveform) of 3.5% was obtained, for Callao station the error was 12% and the largest error was in Chimbote with 53.5%, however, due to the low amplitude of the Chimbote wave (tsunami early warning, where speed is required rather than accuracy, so the results should be taken as preliminary.

  3. Numerical earthquake model of the 31 October 2013 Ruisui, Taiwan, earthquake: Source rupture process and seismic wave propagation

    Science.gov (United States)

    Lee, Shiann-Jong; Huang, Hsin-Hua; Shyu, J. Bruce H.; Yeh, Te-Yang; Lin, Tzu-Chi

    2014-12-01

    We build a numerical earthquake model, including numerical source and wave propagation models, to understand the rupture process and the ground motion time history of the 2013 ML 6.4 Ruisui earthquake in Taiwan. This moderately large event was located in the Longitudinal Valley, a suture zone of the Philippine Sea Plate and the Eurasia Plate. A joint source inversion analysis by using teleseismic body wave, GPS coseismic displacement and near field ground motion data was performed first. The inversion results derived from a western dipping fault plane indicate that the slip occurred in depths between 10 and 20 km. The rupture propagated from south to north and two asperities were resolved. The largest one was located approximately 15 km north of the epicenter with a maximum slip about 1 m. A 3D seismic wave propagation simulation based on the spectral-element method was then carried out by using the inverted source model. A strong rupture directivity effect in the northern area of the Longitudinal Valley was found, which was due to the northward rupture process. Forward synthetic waveforms could explain most of the near-field ground motion data for frequencies between 0.05 and 0.2 Hz. This numerical earthquake model not only helps us confirm the detailed rupture processes on the Central Range Fault but also gives contribution to regional seismic hazard mitigation for future large earthquakes.

  4. Combining stress transfer and source directivity: the case of the 2012 Emilia seismic sequence

    OpenAIRE

    Vincenzo Convertito; Flaminia Catalli; Antonio Emolo

    2013-01-01

    The Emilia seismic sequence (Northern Italy) started on May 2012 and caused 17 casualties, severe damage to dwellings and forced the closure of several factories. The total number of events recorded in one month was about 2100, with local magnitude ranging between 1.0 and 5.9. We investigate potential mechanisms (static and dynamic triggering) that may describe the evolution of the sequence. We consider rupture directivity in the dynamic strain field and observe that, for each main earthquake...

  5. Crowd-Sourcing Seismic Data for Education and Research Opportunities with the Quake-Catcher Network

    Science.gov (United States)

    Sumy, D. F.; DeGroot, R. M.; Benthien, M. L.; Cochran, E. S.; Taber, J. J.

    2016-12-01

    The Quake Catcher Network (QCN; quakecatcher.net) uses low cost micro-electro-mechanical system (MEMS) sensors hosted by volunteers to collect seismic data. Volunteers use accelerometers internal to laptop computers, phones, tablets or small (the size of a matchbox) MEMS sensors plugged into desktop computers using a USB connector to collect scientifically useful data. Data are collected and sent to a central server using the Berkeley Open Infrastructure for Network Computing (BOINC) distributed computing software. Since 2008, sensors installed in museums, schools, offices, and residences have collected thousands of earthquake records, including the 2010 M8.8 Maule, Chile, the 2010 M7.1 Darfield, New Zealand, and 2015 M7.8 Gorkha, Nepal earthquakes. In 2016, the QCN in the United States transitioned to the Incorporated Research Institutions for Seismology (IRIS) Consortium and the Southern California Earthquake Center (SCEC), which are facilities funded through the National Science Foundation and the United States Geological Survey, respectively. The transition has allowed for an influx of new ideas and new education related efforts, which include focused installations in several school districts in southern California, on Native American reservations in North Dakota, and in the most seismically active state in the contiguous U.S. - Oklahoma. We present and describe these recent educational opportunities, and highlight how QCN has engaged a wide sector of the public in scientific data collection, particularly through the QCN-EPIcenter Network and NASA Mars InSight teacher programs. QCN provides the public with information and insight into how seismic data are collected, and how researchers use these data to better understand and characterize seismic activity. Lastly, we describe how students use data recorded by QCN sensors installed in their classrooms to explore and investigate felt earthquakes, and look towards the bright future of the network.

  6. A new tool for rapid and automatic estimation of earthquake source parameters and generation of seismic bulletins

    Science.gov (United States)

    Zollo, Aldo

    2016-04-01

    RISS S.r.l. is a Spin-off company recently born from the initiative of the research group constituting the Seismology Laboratory of the Department of Physics of the University of Naples Federico II. RISS is an innovative start-up, based on the decade-long experience in earthquake monitoring systems and seismic data analysis of its members and has the major goal to transform the most recent innovations of the scientific research into technological products and prototypes. With this aim, RISS has recently started the development of a new software, which is an elegant solution to manage and analyse seismic data and to create automatic earthquake bulletins. The software has been initially developed to manage data recorded at the ISNet network (Irpinia Seismic Network), which is a network of seismic stations deployed in Southern Apennines along the active fault system responsible for the 1980, November 23, MS 6.9 Irpinia earthquake. The software, however, is fully exportable and can be used to manage data from different networks, with any kind of station geometry or network configuration and is able to provide reliable estimates of earthquake source parameters, whichever is the background seismicity level of the area of interest. Here we present the real-time automated procedures and the analyses performed by the software package, which is essentially a chain of different modules, each of them aimed at the automatic computation of a specific source parameter. The P-wave arrival times are first detected on the real-time streaming of data and then the software performs the phase association and earthquake binding. As soon as an event is automatically detected by the binder, the earthquake location coordinates and the origin time are rapidly estimated, using a probabilistic, non-linear, exploration algorithm. Then, the software is able to automatically provide three different magnitude estimates. First, the local magnitude (Ml) is computed, using the peak-to-peak amplitude

  7. The 1946 Unimak Tsunami Earthquake Area: revised tectonic structure in reprocessed seismic images and a suspect near field tsunami source

    Science.gov (United States)

    Miller, John J.; von Huene, Roland E.; Ryan, Holly F.

    2014-01-01

    In 1946 at Unimak Pass, Alaska, a tsunami destroyed the lighthouse at Scotch Cap, Unimak Island, took 159 lives on the Hawaiian Islands, damaged island coastal facilities across the south Pacific, and destroyed a hut in Antarctica. The tsunami magnitude of 9.3 is comparable to the magnitude 9.1 tsunami that devastated the Tohoku coast of Japan in 2011. Both causative earthquake epicenters occurred in shallow reaches of the subduction zone. Contractile tectonism along the Alaska margin presumably generated the far-field tsunami by producing a seafloor elevation change. However, the Scotch Cap lighthouse was destroyed by a near-field tsunami that was probably generated by a coeval large undersea landslide, yet bathymetric surveys showed no fresh large landslide scar. We investigated this problem by reprocessing five seismic lines, presented here as high-resolution graphic images, both uninterpreted and interpreted, and available for the reader to download. In addition, the processed seismic data for each line are available for download as seismic industry-standard SEG-Y files. One line, processed through prestack depth migration, crosses a 10 × 15 kilometer and 800-meter-high hill presumed previously to be basement, but that instead is composed of stratified rock superimposed on the slope sediment. This image and multibeam bathymetry illustrate a slide block that could have sourced the 1946 near-field tsunami because it is positioned within a distance determined by the time between earthquake shaking and the tsunami arrival at Scotch Cap and is consistent with the local extent of high runup of 42 meters along the adjacent Alaskan coast. The Unimak/Scotch Cap margin is structurally similar to the 2011 Tohoku tsunamigenic margin where a large landslide at the trench, coeval with the Tohoku earthquake, has been documented. Further study can improve our understanding of tsunami sources along Alaska’s erosional margins.

  8. Source characterization for an explosion during the 2009 eruption of Redoubt Volcano from very-long-period seismic waves

    Science.gov (United States)

    Haney, Matthew M.; Chouet, Bernard A.; Dawson, Phillip B.; Power, John A.

    2013-01-01

    The 2009 eruption of Redoubt produced several very-long-period (VLP) signals associated with explosions. We invert for the source location and mechanism of an explosion at Redoubt volcano using waveform methods applied to broadband recordings. Such characterization of the source carries information on the geometry of the conduit and the physics of the explosion process. Inversions are carried out assuming the volcanic source can be modeled as a point source, with mechanisms described by a) a set of 3 orthogonal forces, b) a moment tensor consisting of force couples, and c) both forces and moment tensor components. We find that the source of the VLP seismic waves during the explosion is well-described by either a combined moment/force source located northeast of the crater and at an elevation of 1.6 km ASL or a moment source at an elevation of 800 m to the southwest of the crater. The moment tensors for the solutions with moment and force and moment-only share similar characteristics. The source time functions for both moment tensors begin with inflation (pressurization) and execute two cycles of deflation-reinflation (depressurization–repressurization). Although the moment/force source provides a better fit to the data, we find that owing to the limited coverage of the broadband stations at Redoubt the moment-only source is the more robust and reliable solution. Based on the moment-only solution, we estimate a volume change of 19,000 m3 and a pressure change of 7 MPa in a dominant sill and an out-of-phase volume change of 5000 m3 and pressure change of 1.8 MPa in a subdominant dike at the source location. These results shed new light on the magmatic plumbing system beneath Redoubt and complement previous studies on Vulcanian explosions at other volcanoes.

  9. Robotization in Seismic Acquisition

    NARCIS (Netherlands)

    Blacquière, G.; Berkhout, A.J.

    2013-01-01

    The amount of sources and detectors in the seismic method follows "Moore’s Law of seismic data acquisition", i.e., it increases approximately by a factor of 10 every 10 years. Therefore automation is unavoidable, leading to robotization of seismic data acquisition. Recently, we introduced a new

  10. The Seismic Tool-Kit (STK): An Open Source Software For Learning the Basis of Signal Processing and Seismology.

    Science.gov (United States)

    Reymond, D.

    2016-12-01

    We present an open source software project (GNU public license), named STK: Seismic Tool-Kit, that is dedicated mainly for learning signal processing and seismology. The STK project that started in 2007, is hosted by SourceForge.net, and count more than 20000 downloads at the date of writing.The STK project is composed of two main branches:First, a graphical interface dedicated to signal processing (in the SAC format (SAC_ASCII and SAC_BIN): where the signal can be plotted, zoomed, filtered, integrated, derivated, ... etc. (a large variety of IFR and FIR filter is proposed). The passage in the frequency domain via the Fourier transform is used to introduce the estimation of spectral density of the signal , with visualization of the Power Spectral Density (PSD) in linear or log scale, and also the evolutive time-frequency representation (or sonagram). The 3-components signals can be also processed for estimating their polarization properties, either for a given window, or either for evolutive windows along the time. This polarization analysis is useful for extracting the polarized noises, differentiating P waves, Rayleigh waves, Love waves, ... etc. Secondly, a panel of Utilities-Program are proposed for working in a terminal mode, with basic programs for computing azimuth and distance in spherical geometry, inter/auto-correlation, spectral density, time-frequency for an entire directory of signals, focal planes, and main components axis, radiation pattern of P waves, Polarization analysis of different waves (including noise), under/over-sampling the signals, cubic-spline smoothing, and linear/non linear regression analysis of data set. STK is developed in C/C++, mainly under Linux OS, and it has been also partially implemented under MS-Windows. STK has been used in some schools for viewing and plotting seismic records provided by IRIS, and it has been used as a practical support for teaching the basis of signal processing. Useful links:http://sourceforge.net

  11. Source parameters of seismic events potentially associated with damage in block 33/34 of the Kiirunavaara mine (Sweden)

    Science.gov (United States)

    Nordström, Emilia; Dineva, Savka; Nordlund, Erling

    2017-12-01

    Forty-six mining-induced seismic events with moment magnitude between -1.2 and 2.1 that possibly caused damage were studied. The events occurred between 2008 and 2013 at mining level 850-1350 m in the Kiirunavaara Mine (Sweden). Hypocenter locations were refined using from 6 to 130 sensors at distances of up to 1400 m. The source parameters of the events were re-estimated using spectral analysis with a standard Brune model (slope -2). The radiated energy for the studied events varied from 4.7 × 10-1 to 3.8 × 107 J, the source radii from 4 to 110 m, the apparent stress from 6.2 × 102 to 1.1 × 106 Pa, energy ratio ( E s/ E p) from 1.2 to 126, and apparent volume from 1.8 × 103 to 1.1 × 107 m3. 90% of the events were located in the footwall, close to the ore contact. The events were classified as shear/fault slip (FS) or non-shear (NS) based on the E s/ E p ratio (>10 or <10). Out of 46 events 15 events were classified as NS located almost in the whole range between 840 and 1360 m, including many events below the production. The rest 31 FS events were concentrated mostly around the production levels and slightly below them. The relationships between some source parameters and seismic moment/moment magnitude showed dependence on the type of the source mechanism. The energy and the apparent stress were found to be three times larger for FS events than for NS events.

  12. Spectral-element simulations of three-dimensional seismic wave propagation and applications to source and structural inversions

    Science.gov (United States)

    Liu, Qinya

    This thesis presents a concise introduction to the spectral-element method and its applications to the simulation of seismic wave propagation in 3-D earth models. The spectral-element method is implemented in the regional scale for a 3-D integrated southern California velocity model. Significantly better waveform fits are achieved for the 3-D synthetics calculated compare to the 1-D synthetics generated from the 1-D standard southern California model, especially for many basin stations where strong amplifications are observed due to the very low wave-speed sediments. A hypothetical earthquake rupturing from northeast to southwest at the southern end of the San Andreas fault is simulated to improve our understanding of the seismic hazards in the Salton Trough region. With the improved 3-D Green's function, we perform source inversions for both the source mechanisms and event depths of Mw ≥ 3.5 earthquakes in southern California. The inversion results generally agree well with the results obtained by other traditional methods, but with significantly more stations used in the inversions. Time shifts are generally required to align the data and the synthetics, which provides a great dataset for the improvement of the 3-D velocity models in southern California. We use the adjoint method to formulate the tomographic inverse problem based upon a 3-D initial model. We calculate the sensitivity kernels, a key component of the tomographic inversion, that relate the perturbations of observations to the perturbations of the model parameters. These kernels are constructed by the interaction of the regular forward wavefield and the adjoint wavefield generated by putting the time-reversed signals at the receivers as simultaneous adjoint sources. We compute the travel-time sensitivity kernels for typical phases in both regional and global problems for educational purposes, and outline the procedures of applying the conjugate-gradient method to solve both source and structural

  13. FRISK: computer program for seismic risk analysis using faults as earthquake sources

    Science.gov (United States)

    McGuire, Robin K.

    1978-01-01

    This computer program makes probabilistic seismic hazard calculations at sites affected by earthquakes occurring on faults which are defined by the user as a series of line segments. The length of rupture of the fault as a function of earthquake magnitude is accounted for, and ground motion estimates at the site are made using the magnitude of the earthquake and the closest distance from the site to the rupture zone. Uncertainty in the earthquake magnitude, in the rupture given magnitude, in the location of the rupture zone on the fault, in the maximum possible magnitude of earthquakes, and in the ground motion at the site given the earthquake, its size, rupture length, and location, are accounted for explicitly. FRISK (Fault RISK) was written to take advantage of repeated calculations, so that seismic hazard analyses for several ground motion parameters (for instance, peak ground acceleration, velocity, and displacement), and for several sites, are most efficiently made with one execution of the program rather than with repeated executions. The program uses a step-truncated exponential distribution for earthquake magnitude, a lognormal distribution for rupture length given magnitude, a uniform distribution for rupture location on faults, and a lognormal distribution of site amplitude given magnitude of the earthquake and distance from the rupture zone to the site. The program has been structured so that other functions may easily be substituted if this is appropriate for a particular problem; for example a wide range of deterministic or probabilistic geophysical models for estimating ground motion may be incorporated, and the program will yield probabilistic estimates of seismic hazard.

  14. The dynamics of cavity clusters in ultrasonic (vibratory) cavitation erosion

    DEFF Research Database (Denmark)

    Hansson, I.; Mørch, Knud Aage

    1980-01-01

    The erosion of solids caused by cavitating liquids is a result of the concerted collapse of clusters of cavities. In vibratory cavitation equipment the clusters grow and collapse adjacent to a solid surface and are typically of hemispherical or cylindrical form. In the present paper the collapse...... process of these clusters is described and the collapse equations are developed and solved. The theoretical results are compared with results from high-speed photography of the clusters and with the initial stages of cavitation erosion on metal specimens. Experimental and theoretical results show...

  15. Used Furan Sand Reclamation in REGMAS Vibratory Unit

    Directory of Open Access Journals (Sweden)

    Dańko J.

    2015-09-01

    Full Text Available The paper, especially dealt with problems of reclamation of used furan sand, carried out in new, vibratory sand reclamation unit REGMAS developed by researches from AGH-University of Science and Technology, Faculty of Foundry Engineering in Cracow (Poland. Functional characteristics of reclamation unit as well as the results of reclamation of used sand with furfuryl resin are discussed in the paper. The quality of reclaim was tested by means of the LOI and pH value, dust content in the reclaim and at least by the the quality of the castings produced in moulds prepared with the use of reclaimed matrix.

  16. Electric effects induced by artificial seismic sources at Somma-Vesuvius volcano

    Directory of Open Access Journals (Sweden)

    Rosa Di Maio

    2013-11-01

    Full Text Available In this paper, we present a series of self-potential measurements at Somma-Vesuvius volcanic area acquired in conjunction with an active seismic tomography survey. The aim of our study is both to provide further confirmation to the occurrence of seismo-electric coupling and to identify sites suitable for self-potential signal monitoring at Somma-Vesuvius district. The data, which were collected along two perpendicular dipoles, show significant changes on the natural electric field pattern. These variations, attributable to electrokinetic processes triggered by the artificial seismic waves, were observed after explosions occurred at a distance less than 5 km from the SP dipole arrays. In particular, we found that the NW-SE component of the natural electric field was more sensible to the shots than the NE-SW one, and the major effects did not correspond to the nearest shots. Such evidences were interpreted considering the underground electrical properties as deduced by previous detailed resistivity and self-potential surveys performed in the study area.

  17. Field Tests to Investigate the Penetration Rate of Piles Driven by Vibratory Installation

    Directory of Open Access Journals (Sweden)

    Zhaohui Qin

    2017-01-01

    Full Text Available Factors directly affecting the penetration rate of piles installed by vibratory driving technique are summarized and classified into seven aspects which are driving force, resistance, vibratory amplitude, energy consumption, speeding up at the beginning, pile plumbness keeping, and slowing down at the end, from the mechanism and engineering practice of the vibratory pile driving. In order to find out how these factors affect the penetration rate of the pile in three major actors of vibratory pile driving: (i the pile to be driven, (ii the selected driving system, and (iii the imposed soil conditions, field tests on steel sheet piles driven by vibratory driving technique in different soil conditions are conducted. The penetration rates of three different sheet pile types having up to four different lengths installed using two different vibratory driving systems are documented. Piles with different lengths and types driven with or without clutch have different penetration rates. The working parameters of vibratory hammer, such as driving force and vibratory amplitude, have great influences on the penetration rate of the pile, especially at the later stages of the sinking process. Penetration rate of piles driven in different soil conditions is uniform because of the different penetration resistance including shaft friction and toe resistance.

  18. Structural variation of the oceanic Moho in the Pacific plate revealed by active-source seismic data

    Science.gov (United States)

    Ohira, Akane; Kodaira, Shuichi; Nakamura, Yasuyuki; Fujie, Gou; Arai, Ryuta; Miura, Seiichi

    2017-10-01

    The characteristics of the oceanic Moho are known to depend on various factors, such as seafloor spreading rate, crustal age, and accretionary processes at a ridge. However, the effect of local magmatic activities on the seismic signature of the Moho is poorly understood. Here an active-source reflection and refraction survey is used to investigate crustal structure and Moho characteristics along a >1000-km-long profile southeast of the Shatsky Rise in a Pacific Ocean basin formed from the Late Jurassic to Early Cretaceous and spanning the onset of Shatsky Rise volcanism. Although the seismic velocity structure estimated from the refraction data showed typical characteristics of the oceanic crust of the old Pacific plate, the appearance of the Moho reflections was spatially variable. We observed clear Moho reflections such as those to be expected where the spreading rate is fast to intermediate only at the southwestern end of the profile, whereas Moho reflections were diffuse, weak, or absent along other parts of the profile. The poor Moho reflections can be explained by the presence of a thick crust-mantle transition layer, which is temporally coincident with the formation of the Shatsky Rise. We inferred that the crust-mantle transition layer was formed by changes in on-axis accretion process or modification of the primary Moho by off-axis magmatism, induced by magmatic activity of the Shatsky Rise.

  19. Combining stress transfer and source directivity: the case of the 2012 Emilia seismic sequence.

    Science.gov (United States)

    Convertito, Vincenzo; Catalli, Flaminia; Emolo, Antonio

    2013-11-01

    The Emilia seismic sequence (Northern Italy) started on May 2012 and caused 17 casualties, severe damage to dwellings and forced the closure of several factories. The total number of events recorded in one month was about 2100, with local magnitude ranging between 1.0 and 5.9. We investigate potential mechanisms (static and dynamic triggering) that may describe the evolution of the sequence. We consider rupture directivity in the dynamic strain field and observe that, for each main earthquake, its aftershocks and the subsequent large event occurred in an area characterized by higher dynamic strains and corresponding to the dominant rupture direction. We find that static stress redistribution alone is not capable of explaining the locations of subsequent events. We conclude that dynamic triggering played a significant role in driving the sequence. This triggering was also associated with a variation in permeability and a pore pressure increase in an area characterized by a massive presence of fluids.

  20. Combining stress transfer and source directivity: the case of the 2012 Emilia seismic sequence

    Science.gov (United States)

    Convertito, Vincenzo; Catalli, Flaminia; Emolo, Antonio

    2013-11-01

    The Emilia seismic sequence (Northern Italy) started on May 2012 and caused 17 casualties, severe damage to dwellings and forced the closure of several factories. The total number of events recorded in one month was about 2100, with local magnitude ranging between 1.0 and 5.9. We investigate potential mechanisms (static and dynamic triggering) that may describe the evolution of the sequence. We consider rupture directivity in the dynamic strain field and observe that, for each main earthquake, its aftershocks and the subsequent large event occurred in an area characterized by higher dynamic strains and corresponding to the dominant rupture direction. We find that static stress redistribution alone is not capable of explaining the locations of subsequent events. We conclude that dynamic triggering played a significant role in driving the sequence. This triggering was also associated with a variation in permeability and a pore pressure increase in an area characterized by a massive presence of fluids.

  1. Using synthetic kinematic source inversions with dynamic rupture models to evaluate the effect of seismic network density and geometry in near-field source inversions

    Science.gov (United States)

    Zhang, Y.; Dalguer, L. A.; Song, S.; Clinton, J. F.

    2013-12-01

    Detailed source imaging of the spatial and temporal slip distribution of earthquakes is a main research goal for seismology. In this study we investigate how the number and geometrical distribution of seismic stations affect finite kinematic source inversion results by inverting ground motions derived from a known synthetic dynamic earthquake rupture model, which is governed by the slip weakening friction law with heterogeneous stress distribution. Our target dynamic rupture model is a buried strike-slip event (Mw 6.5) in a layered half space (Dalguer & Mai, 2011) with broadband synthetic ground motions created at 168 near-field stations. In the inversion, we modeled low frequency (under 1Hz) waveforms using a genetic algorithm in a Bayesian framework (Moneli et al. 2008) to retrieve peak slip velocity, rupture time, and rise time of the source. The dynamic consistent regularized Yoffe function (Tinti et al. 2005) was applied as a single window slip velocity function. Tikhonov regularization was used to smooth final slip. We tested three station network geometry cases: (a) single station, in which we inverted 3 component waveforms from a single station varying azimuth and epicentral distance; (b) multi-station configurations with similar numbers of stations all at similar distances from, but regularly spaced around the fault; (c) irregular multi-station configurations using different numbers of stations. For analysis, waveform misfits are calculated using all 168 stations. Our results show: 1) single station tests suggest that it may be possible to obtain a relatively good source model even using one station, with a waveform misfit comparable to that obtained with the best source model. The best single station performance occurs with stations in which amplitude ratios between the three components are not large, indicating that P & S waves are all present. We infer that both body wave radiation pattern and distance play an important role in selection of optimal

  2. Brief communication "Seismic and acoustic-gravity signals from the source of the 2004 Indian Ocean Tsunami"

    Directory of Open Access Journals (Sweden)

    A. Raveloson

    2012-02-01

    Full Text Available The great Sumatra-Andaman earthquake of 26 December 2004 caused seismic waves propagating through the solid Earth, tsunami waves propagating through the ocean and infrasound or acoustic-gravity waves propagating through the atmosphere. Since the infrasound wave travels faster than its associated tsunami, it is for warning purposes very intriguing to study the possibility of infrasound generation directly at the earthquake source. Garces et al. (2005 and Le Pichon et al. (2005 emphasized that infrasound was generated by mountainous islands near the epicenter and by tsunami propagation along the continental shelf to the Bay of Bengal. Mikumo et al. (2008 concluded from the analysis of travel times and amplitudes of first arriving acoustic-gravity waves with periods of about 400–700 s that these waves are caused by coseismic motion of the sea surface mainly to the west of the Nicobar islands in the open seas. We reanalyzed the acoustic-gravity waves and corrected the first arrival times of Mikumo et al. (2008 by up to 20 min. We found the source of the first arriving acoustic-gravity wave about 300 km to the north of the US Geological Survey earthquake epicenter. This confirms the result of Mikumo et al. (2008 that sea level changes at the earthquake source cause long period acoustic-gravity waves, which indicate that a tsunami was generated. Therefore, a denser local network of infrasound stations may be helpful for tsunami warnings, not only for very large earthquakes.

  3. When probabilistic seismic hazard climbs volcanoes: the Mt. Etna case, Italy – Part 1: Model components for sources parameterization

    Directory of Open Access Journals (Sweden)

    R. Azzaro

    2017-11-01

    Full Text Available The volcanic region of Mt. Etna (Sicily, Italy represents a perfect lab for testing innovative approaches to seismic hazard assessment. This is largely due to the long record of historical and recent observations of seismic and tectonic phenomena, the high quality of various geophysical monitoring and particularly the rapid geodynamics clearly demonstrate some seismotectonic processes. We present here the model components and the procedures adopted for defining seismic sources to be used in a new generation of probabilistic seismic hazard assessment (PSHA, the first results and maps of which are presented in a companion paper, Peruzza et al. (2017. The sources include, with increasing complexity, seismic zones, individual faults and gridded point sources that are obtained by integrating geological field data with long and short earthquake datasets (the historical macroseismic catalogue, which covers about 3 centuries, and a high-quality instrumental location database for the last decades. The analysis of the frequency–magnitude distribution identifies two main fault systems within the volcanic complex featuring different seismic rates that are controlled essentially by volcano-tectonic processes. We discuss the variability of the mean occurrence times of major earthquakes along the main Etnean faults by using an historical approach and a purely geologic method. We derive a magnitude–size scaling relationship specifically for this volcanic area, which has been implemented into a recently developed software tool – FiSH (Pace et al., 2016 – that we use to calculate the characteristic magnitudes and the related mean recurrence times expected for each fault. Results suggest that for the Mt. Etna area, the traditional assumptions of uniform and Poissonian seismicity can be relaxed; a time-dependent fault-based modeling, joined with a 3-D imaging of volcano-tectonic sources depicted by the recent instrumental seismicity, can therefore be

  4. Marine and land active-source seismic imaging of mid-Miocene to Holocene-aged faulting near geothermal prospects at Pyramid Lake, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Eisses, A.; Kell, A.; Kent, G. [UNR; Driscoll, N. [UCSD; Karlin, R.; Baskin, R. [USGS; Louie, J. [UNR; Pullammanappallil, S. [Optim

    2016-08-01

    Amy Eisses, Annie Kell, Graham Kent, Neal Driscoll, Robert Karlin, Rob Baskin, John Louie, and Satish Pullammanappallil, 2011, Marine and land active-source seismic imaging of mid-Miocene to Holocene-aged faulting near geothermal prospects at Pyramid Lake, Nevada: presented at Geothermal Resources Council Annual Meeting, San Diego, Oct. 23-26.

  5. Urban shear-wave reflection seismics: Reconstruction support by combined shallow seismic and engineering geology investigations

    Science.gov (United States)

    Polom, U.; Guenther, A.; Arsyad, I.; Wiyono, P.; Krawczyk, C. M.

    2009-12-01

    After the big 2004 Sumatra-Andaman earthquake, the massive reconstruction activities in the Aceh province (Northern Sumatra) were promoted by the Republic of Indonesia and the Federal Ministry of Economic Cooperation and Development. The aims of the project MANGEONAD (Management of Georisk Nanggroe Aceh Darussalam). are to establish geoscientific on the ground support for a sustainable development and management of save building constructions, lifelines, infrastructure and also natural resources. Therefore, shallow shear-wave reflection seismics was applied in close combination to engineering geology investigations in the period between 2005-2009 since depth and internal structure of the Krueng Aceh River delta (mainly young alluvial sediments) were widely unknown. Due to the requirements in the densely populated Banda Aceh region, lacking also traffic infrastructure, a small and lightweight engineering seismic setup of high mobility and high subsurface resolution capability was chosen. The S-wave land streamer system with 48 channels was applied successfully together with the ELVIS vibratory source using S- and P-waves on paved roads within the city of Banda Aceh. The performance of the S-wave system enabled the detailed seismic investigation of the shallow subsurface down to 50-150 m depth generating shaking frequencies between 20 Hz to 200 Hz. This also provides depth information extending the maximum depths of boreholes and Standard Penetrometer Testings (SPT), which could only be applied to max. 20 m depth. To integrate the results gained from all three methods, and further to provide a fast statistical analysis tool for engineering use, the Information System Engineering Geology (ISEG, BGR) was developed. This geospatial information tool includes the seismic data, all borehole information, geotechnical SPT and laboratory results from samples available in the investigation area. Thereby, the geotechnical 3D analysis of the subsurface units is enabled. The

  6. Estimation of earthquake source parameters in the Kachchh seismic zone, Gujarat, India, using three component S-wave spectra

    Science.gov (United States)

    Nagamani, Durgada; Mandal, Prantik

    2017-07-01

    Earthquake source parameters and crustal Q0 values for the 138 selected local events of (Mw{:}2.5{-}4.4) the 2001 Bhuj earthquake sequence have been computed through inversion modelling of S-waves from three-component broadband seismometer data. SEISAN software has been used to locate the identified local earthquakes, which were recorded at least three or more stations of the Kachchh seismological network. Three component spectra of S-wave are being inverted by using the Levenberg-Marquardt non-linear inversion technique, wherein the inversion scheme is formulated based on ω 2 source model. SAC Software (seismic analysis code) is being utilized for calculating three-component displacement and velocity spectra of S-wave. The displacement spectra are used for estimating corner frequency (in Hz) and long period spectral level (in nm-s). These two parameters play a key role in estimating earthquake source parameters. The crustal {Q}0 values have been computed simultaneously for each component of three-component broadband seismograph. The estimated seismic moment (M0) and source radius ( r) using S-wave spectra range from 7.03E+12 to 5.36E+15 N-m and 178.56 to 565.21 m, respectively. The corner frequencies for S-wave vary from 3.025 to 7.425 Hz. We also estimated the radiated energy (ES) using velocity spectra, which is varying from 2.76E+06 to 4.07E+11 Joules. The estimated apparent stress drop and static stress drop values range from 0.01 to 2.56 and 0.53 to 36.79 MPa, respectively. Our study also reveals that estimated Q0 values vary from 119.0 to 7229.5, with an average Q0 value of 701. Another important parameter, by which the earthquake rupture process can be recognized, is Zuniga parameter. It suggests that most of the Kachchh events follow the frictional overshoot model. Our estimated static stress drop values are higher than the apparent stress drop values. And the stress drop values are quite larger for intraplate earthquakes than the interplate earthquakes.

  7. Adaptive Control of a Vibratory Angle Measuring Gyroscope

    Science.gov (United States)

    Park, Sungsu

    2010-01-01

    This paper presents an adaptive control algorithm for realizing a vibratory angle measuring gyroscope so that rotation angle can be directly measured without integration of angular rate, thus eliminating the accumulation of numerical integration errors. The proposed control algorithm uses a trajectory following approach and the reference trajectory is generated by an ideal angle measuring gyroscope driven by the estimate of angular rate and the auxiliary sinusoidal input so that the persistent excitation condition is satisfied. The developed control algorithm can compensate for all types of fabrication imperfections such as coupled damping and stiffness, and mismatched stiffness and un-equal damping term in an on-line fashion. The simulation results show the feasibility and effectiveness of the developed control algorithm that is capable of directly measuring rotation angle without the integration of angular rate. PMID:22163667

  8. Climate Change and Some Other Implications of Vibratory Existence

    Directory of Open Access Journals (Sweden)

    Glenn McLaren

    2009-11-01

    Full Text Available Modern Process Philosophy began when Alfred North Whitehead realized that existence is primarily vibratory, not points but processes. Vibrations are best understood as sound waves, or through using auditory metaphors rather than visual ones. Our Universe is more like music than matter, but how does this help us better understand it? In this paper I use the example of the large ocean current oscillators that help drive our climate systems to reveal the more effective nature of auditory approaches. Through an auditory approach, we can better understand the ways these oscillations constrain and interact with other levels of oscillations as well as how they might be destroyed by other levels. This can then lead to us extending our ethics to the conservation of these oscillations.

  9. Regularized least-squares migration of simultaneous-source seismic data with adaptive singular spectrum analysis.

    Science.gov (United States)

    Li, Chuang; Huang, Jian-Ping; Li, Zhen-Chun; Wang, Rong-Rong

    2017-01-01

    Simultaneous-source acquisition has been recognized as an economic and efficient acquisition method, but the direct imaging of the simultaneous-source data produces migration artifacts because of the interference of adjacent sources. To overcome this problem, we propose the regularized least-squares reverse time migration method (RLSRTM) using the singular spectrum analysis technique that imposes sparseness constraints on the inverted model. Additionally, the difference spectrum theory of singular values is presented so that RLSRTM can be implemented adaptively to eliminate the migration artifacts. With numerical tests on a flat layer model and a Marmousi model, we validate the superior imaging quality, efficiency and convergence of RLSRTM compared with LSRTM when dealing with simultaneous-source data, incomplete data and noisy data.

  10. The odds of a seismic source near Dwarka, NW Gujarat: An evaluation based on proxies

    Digital Repository Service at National Institute of Oceanography (India)

    Rajendran, C.P.; Rajendran, K.; Vora, K.H.; Gaur, A

    The Kachchh–Saurashtra region is part of an old rift basin, featuring a number of linear structures, some of them holding potential for occasional M > 7 earthquakes. A challenging question is to identify probable sources of large earthquakes...

  11. Reflection processing of the large-N seismic data from the Source Physics Experiment (SPE)

    Energy Technology Data Exchange (ETDEWEB)

    Paschall, Olivia C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-07-18

    The purpose of the SPE is to develop a more physics-based model for nuclear explosion identification to understand the development of S-waves from explosion sources in order to enhance nuclear test ban treaty monitoring.

  12. Evidence for gas and magmatic sources beneath the Yellowstone volcanic field from seismic tomographic imaging

    Science.gov (United States)

    Husen, Stephan; Smith, Robert B.; Waite, Gregory P.

    2004-03-01

    The 3-D P-wave velocity and P- to S-wave velocity ratio structure of the Yellowstone volcanic field, Wyoming, has been determined from local earthquake tomography using new data from the permanent Yellowstone seismic network. We selected 3374 local earthquakes between 1995 and 2001 to invert for the 3-D P-wave velocity ( Vp) and P-wave to S-wave velocity ratio ( Vp/ Vs) structure. Vp anomalies of small size (15×15 km) are reliably imaged in the northwestern part of the model outside the Yellowstone caldera; inside the caldera only Vp anomalies of large size extending over several grid nodes are reliably imaged. The Vp/ Vs solution is generally poorer due to the low number of S-P arrival times. Only the northwestern part of the model is resolved with confidence; the Vp/ Vs solution also suffers from strong vertical and horizontal velocity smearing. The tomographic images confirm the existence of a low Vp-body beneath the Yellowstone caldera at depths greater than 8 km, possibly representing hot, crystallizing magma. The most striking result of our study is a volume of anomalously low Vp and Vp/ Vs in the northwestern part of the Yellowstone volcanic field at shallow depths of <2.0 km. Theoretical calculations of changes in P- to S-wave velocity ratios indicate that these anomalies can be interpreted as porous, gas-filled rock. The close spatial correlation of the observed anomalies and the occurrence of the largest earthquake swarm in historic time in Yellowstone, 1985, suggest that the gas may have originated as part of magmatic fluids released by crystallization of magma beneath the Yellowstone caldera.

  13. The Numerical FEM Model of the Kinematics of the Vibratory Shot Peening Process

    Directory of Open Access Journals (Sweden)

    Stanisław Bławucki

    2017-12-01

    Full Text Available The paper presents the results of numerical calculations, with the finite element method in the ABAQUS program environment, of the vibratory shot peening process with loose peening elements. The behaviour of shot peening elements was analysed in the kinematic aspect. The impact of the initial deployment of vibratory shot peening elements on their behaviour during processing was investigated, including the displacement, velocity, acceleration and the number of collisions. The way of determining the effectiveness of the processing with the vibratory shot peening was illustrated.

  14. Seismic source dynamics of gas-piston activity at Kı̄lauea Volcano, Hawai‘i

    Science.gov (United States)

    Chouet, Bernard A.; Dawson, Phillip B.

    2015-01-01

    Since 2008, eruptive activity at the summit of Kı̄lauea Volcano, Hawai‘i has been confined to the new Overlook pit crater within the Halema‘uma‘u Crater. Among the broad range of magmatic processes observed in the new pit are recurring episodes of gas pistoning. The gas-piston activity is accompanied by seismic signals that are recorded by a broadband network deployed in the summit caldera. We use raw data recorded with this network to model the source mechanism of representative gas-piston events in a sequence that occurred on 20–25 August 2011 during a gentle inflation of the Kı̄lauea summit. To determine the source centroid location and source mechanism, we minimize the residual error between data and synthetics calculated by the finite difference method for a point source embedded in a homogeneous medium that takes topography into account. We apply a new waveform inversion method that accounts for the contributions from both translation and tilt in horizontal seismograms through the use of Green's functions representing the seismometer response to translation and tilt ground motions. This method enables a robust description of the source mechanism over the period range 1–10,000 s. Most of the seismic wavefield produced by gas-pistoning originates in a source region ∼1 km below the eastern perimeter of the Halema‘uma‘u pit crater. The observed waveforms are well explained by a simple volumetric source with geometry composed of two intersecting cracks featuring an east striking crack (dike) dipping 80°to the north, intersecting a north striking crack (another dike) dipping 65° to the east. Each gas-piston event is marked by a similar rapid inflation lasting a few minutes, trailed by a slower deflation ramp extending up to 15 min, attributed to the efficient coupling at the source centroid location of the pressure and momentum changes accompanying the growth and collapse of a layer of foam at the top of the lava column. Assuming a

  15. Seismic source dynamics of gas-piston activity at Kı¯lauea Volcano, Hawai`i

    Science.gov (United States)

    Chouet, Bernard; Dawson, Phillip

    2015-04-01

    Since 2008, eruptive activity at the summit of Kı¯lauea Volcano, Hawai`i has been confined to the new Overlook pit crater within the Halema`uma`u Crater. Among the broad range of magmatic processes observed in the new pit are recurring episodes of gas pistoning. The gas-piston activity is accompanied by seismic signals that are recorded by a broadband network deployed in the summit caldera. We use raw data recorded with this network to model the source mechanism of representative gas-piston events in a sequence that occurred on 20-25 August 2011 during a gentle inflation of the Kı¯lauea summit. To determine the source centroid location and source mechanism, we minimize the residual error between data and synthetics calculated by the finite difference method for a point source embedded in a homogeneous medium that takes topography into account. We apply a new waveform inversion method that accounts for the contributions from both translation and tilt in horizontal seismograms through the use of Green's functions representing the seismometer response to translation and tilt ground motions. This method enables a robust description of the source mechanism over the period range 1-10,000 s. Most of the seismic wavefield produced by gas-pistoning originates in a source region ˜1 km below the eastern perimeter of the Halema`uma`u pit crater. The observed waveforms are well explained by a simple volumetric source with geometry composed of two intersecting cracks featuring an east striking crack (dike) dipping 80°to the north, intersecting a north striking crack (another dike) dipping 65° to the east. Each gas-piston event is marked by a similar rapid inflation lasting a few minutes, trailed by a slower deflation ramp extending up to 15 min, attributed to the efficient coupling at the source centroid location of the pressure and momentum changes accompanying the growth and collapse of a layer of foam at the top of the lava column. Assuming a simple lumped parameter

  16. Stable grid refinement and singular source discretization for seismic wave simulations

    Energy Technology Data Exchange (ETDEWEB)

    Petersson, N A; Sjogreen, B

    2009-10-30

    An energy conserving discretization of the elastic wave equation in second order formulation is developed for a composite grid, consisting of a set of structured rectangular component grids with hanging nodes on the grid refinement interface. Previously developed summation-by-parts properties are generalized to devise a stable second order accurate coupling of the solution across mesh refinement interfaces. The discretization of singular source terms of point force and point moment tensor type are also studied. Based on enforcing discrete moment conditions that mimic properties of the Dirac distribution and its gradient, previous single grid formulas are generalized to work in the vicinity of grid refinement interfaces. These source discretization formulas are shown to give second order accuracy in the solution, with the error being essentially independent of the distance between the source and the grid refinement boundary. Several numerical examples are given to illustrate the properties of the proposed method.

  17. Structure of the sedimentary cover: The S22 cruise 30 L airgun source seismic reflection studies

    Digital Repository Service at National Institute of Oceanography (India)

    Neprochnov, Y.P.; Murthy, K.S.R.; Levchenko, O.V.; Milanovsky, V.E.; Basnak, V.V.; Buravtsev, A.A; Rao, T.C.S.; Lakshminarayana, S.

    stream_size 9 stream_content_type text/plain stream_name Mem_Geol_Soc_India_1998_39_112.pdf.txt stream_source_info Mem_Geol_Soc_India_1998_39_112.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO-8859-1 ...

  18. Active Faults and Seismic Sources of the Middle East Region: Earthquake Model of the Middle East (EMME) Project

    Science.gov (United States)

    Gulen, L.; EMME WP2 Team*

    2011-12-01

    The Earthquake Model of the Middle East (EMME) Project is a regional project of the GEM (Global Earthquake Model) project (http://www.emme-gem.org/). The EMME project covers Turkey, Georgia, Armenia, Azerbaijan, Syria, Lebanon, Jordan, Iran, Pakistan, and Afghanistan. Both EMME and SHARE projects overlap and Turkey becomes a bridge connecting the two projects. The Middle East region is tectonically and seismically very active part of the Alpine-Himalayan orogenic belt. Many major earthquakes have occurred in this region over the years causing casualties in the millions. The EMME project consists of three main modules: hazard, risk, and socio-economic modules. The EMME project uses PSHA approach for earthquake hazard and the existing source models have been revised or modified by the incorporation of newly acquired data. The most distinguishing aspect of the EMME project from the previous ones is its dynamic character. This very important characteristic is accomplished by the design of a flexible and scalable database that permits continuous update, refinement, and analysis. An up-to-date earthquake catalog of the Middle East region has been prepared and declustered by the WP1 team. EMME WP2 team has prepared a digital active fault map of the Middle East region in ArcGIS format. We have constructed a database of fault parameters for active faults that are capable of generating earthquakes above a threshold magnitude of Mw≥5.5. The EMME project database includes information on the geometry and rates of movement of faults in a "Fault Section Database", which contains 36 entries for each fault section. The "Fault Section" concept has a physical significance, in that if one or more fault parameters change, a new fault section is defined along a fault zone. So far 6,991 Fault Sections have been defined and 83,402 km of faults are fully parameterized in the Middle East region. A separate "Paleo-Sites Database" includes information on the timing and amounts of fault

  19. The evaluation of the earthquake hazard using the exponential distribution method for different seismic source regions in and around Ağrı

    Energy Technology Data Exchange (ETDEWEB)

    Bayrak, Yusuf, E-mail: ybayrak@agri.edu.tr [Ağrı İbrahim Çeçen University, Ağrı/Turkey (Turkey); Türker, Tuğba, E-mail: tturker@ktu.edu.tr [Karadeniz Technical University, Department of Geophysics, Trabzon/Turkey (Turkey)

    2016-04-18

    The aim of this study; were determined of the earthquake hazard using the exponential distribution method for different seismic sources of the Ağrı and vicinity. A homogeneous earthquake catalog has been examined for 1900-2015 (the instrumental period) with 456 earthquake data for Ağrı and vicinity. Catalog; Bogazici University Kandilli Observatory and Earthquake Research Institute (Burke), National Earthquake Monitoring Center (NEMC), TUBITAK, TURKNET the International Seismological Center (ISC), Seismological Research Institute (IRIS) has been created using different catalogs like. Ağrı and vicinity are divided into 7 different seismic source regions with epicenter distribution of formed earthquakes in the instrumental period, focal mechanism solutions, and existing tectonic structures. In the study, the average magnitude value are calculated according to the specified magnitude ranges for 7 different seismic source region. According to the estimated calculations for 7 different seismic source regions, the biggest difference corresponding with the classes of determined magnitudes between observed and expected cumulative probabilities are determined. The recurrence period and earthquake occurrence number per year are estimated of occurring earthquakes in the Ağrı and vicinity. As a result, 7 different seismic source regions are determined occurrence probabilities of an earthquake 3.2 magnitude, Region 1 was greater than 6.7 magnitude, Region 2 was greater than than 4.7 magnitude, Region 3 was greater than 5.2 magnitude, Region 4 was greater than 6.2 magnitude, Region 5 was greater than 5.7 magnitude, Region 6 was greater than 7.2 magnitude, Region 7 was greater than 6.2 magnitude. The highest observed magnitude 7 different seismic source regions of Ağrı and vicinity are estimated 7 magnitude in Region 6. Region 6 are determined according to determining magnitudes, occurrence years of earthquakes in the future years, respectively, 7.2 magnitude was in 158

  20. Electroejaculation versus vibratory stimulation in spinal cord injured men: sperm quality and patient preference.

    Science.gov (United States)

    Ohl, D A; Sønksen, J; Menge, A C; McCabe, M; Keller, L M

    1997-06-01

    We compared semen quality and patient preference between penile vibratory stimulation and electroejaculation in spinal cord injured men. We treated 11 spinal cord injured men with penile vibratory stimulation and electroejaculation in random order. End points examined were semen analysis, sperm functional assessment, and patient pain scores (1 to 10) and preferred procedure. Differences between the procedures were determined with the paired Student t test. There was no difference in antegrade sperm count but penile vibratory stimulation specimens had greater motility (26.0 versus 10.7%), viability (25.2 versus 9.7%) and motile sperm count (185.0 x 10(6) versus 97.0 x 10(6)). The retrograde sperm count was greater (but not significant) in electroejaculation patients. The total (antegrade plus retrograde) and motile sperm counts were not different. There was no difference in immunobead test (all negative), cervical mucus penetration or sperm penetration assay, although the percent hamster egg penetration approached significance (53.7% for penile vibratory stimulation versus 22.1% for electroejaculation, p = 0.06). There was no difference in the peak blood pressures and no complications were noted. Pain scores were significantly greater for electroejaculation compared to penile vibratory stimulation (5.2 versus 1.7, respectively). All patients preferred penile vibratory stimulation. There was a slight advantage in sperm quality and a high patient preference in favor of penile vibratory stimulation. Penile vibratory stimulation should be attempted first to induce ejaculation in spinal cord injured men, with electroejaculation reserved for failures.

  1. Sphincteric events during penile vibratory ejaculation and electroejaculation in men with spinal cord injuries.

    Science.gov (United States)

    Sønksen, J; Ohl, D A; Wedemeyer, G

    2001-02-01

    We investigate internal and external sphincter responses during penile vibratory stimulation and electroejaculation in men with spinal cord injury. Ejaculation induction with simultaneous recording of external and internal sphincter pressures was performed in 9 spinal cord injured men. Of the patients with upper motor neuron lesions 3 underwent penile vibratory stimulation and 3 underwent electroejaculation. In 3 men who did not respond to PVS, including 1 with upper motor neuron and 2 with lower motor neuron lesions, penile vibratory stimulation and subsequent electroejaculation were performed. In successful penile vibratory stimulation and electroejaculation upper motor neuron cases external sphincter pressure first reached a peak (average 180 cm. H2O) and subsequently decrease followed in 3 to 10 seconds by a peak in internal sphincter pressure (average 178 cm. H2O), which exceeded external sphincter pressure and ejaculation occurred. During electroejaculation, the pattern progressed, despite complete discontinuation of electrical stimulation. In electroejaculation, there was a trend for a more rapid return of external sphincter pressure greater than internal sphincter pressure, which may explain the electroejaculation retrograde fraction. In nonresponders external sphincter pressure never increased to more than 105 cm. H2O in response to penile vibratory stimulation and no ejaculation was induced. In nonresponders to penile vibratory stimulation, electroejaculation induced a typical sustained increase in internal sphincter pressure and external sphincter pressure but at lower peak pressures. Forceful contraction of the external sphincter followed by contraction of the internal sphincter always precedes ejaculation during electroejaculation and penile vibratory stimulation. Similarities between penile vibratory stimulation and electroejaculation suggest that the latter induces ejaculation via a complex neurological pathway rather than by simple direct end organ

  2. Jean-Martin Charcot and his vibratory chair for Parkinson disease.

    Science.gov (United States)

    Goetz, Christopher G

    2009-08-11

    Vibration therapy is currently used in diverse medical specialties ranging from orthopedics to urology to sports medicine. The celebrated 19th-century neurologist, J.-M. Charcot, used vibratory therapy to treat Parkinson disease (PD). This study analyzed printed writings by Charcot and other writers on vibratory therapy and accessed unpublished notes from the Salpêtrière Hospital, Paris. Charcot lectured on several occasions on vibratory therapy and its neurologic applications. He developed a vibration chair for patients with PD after he observed that patients were more comfortable and slept better after a train or carriage ride. He replicated this experience by having patients undergo daily 30-minute sessions in the automated vibratory chair (fauteuil trépidant). His junior colleague, Gilles de la Tourette, extended these observations and developed a helmet that vibrated the head on the premise that the brain responded directly to the pulsations. Although after Charcot's death vibratory therapy was not widely pursued, vibratory appliances are reemerging in 21st century medicine and can be retested using adaptations of Charcot's neurologic protocols.

  3. Vocal fold vibratory characteristics of healthy geriatric females--analysis of high-speed digital images.

    Science.gov (United States)

    Ahmad, Kartini; Yan, Yuling; Bless, Diane

    2012-11-01

    A high proportion of the geriatric population suffers from presbylaryngis and presbyphonia; however, our knowledge of vibratory patterns in this population is almost nonexistent. In this study, we investigate the vocal fold vibratory patterns of healthy elderly females to determine which features or combination of them could best describe the geriatric voices. Cross-sectional study with 20 elderly healthy females with no history of voice problems. Hilbert transformed glottal area waveforms (GAWs) from serial high-speed digital imaging of sustained phonation are used to provide quantitative measures of glottal vibratory characteristics and perturbations; open quotient, jitter, and shimmer. Nyquist plots provide interpretable patterns to portray the vibratory characteristics as clear, pressed, breathy, and atypical patterns. The GAW from most elderly speakers (50%) showed vibratory characteristics associated with a more pressed voice and higher glottal perturbation values: their Nyquist plot patterns show wide scatterings around the rim of the plot reflecting a much-reduced ability in sustaining vibratory oscillation; these were distinct differences from previously reported data on younger speakers. Qualitative examination revealed more anteriorly placed glottal gaps in the geriatric females. These findings have important implications in understanding voice production in the geriatric population and in helping to establish normal perturbation references among female speakers across age. Copyright © 2012 The Voice Foundation. All rights reserved.

  4. Semen quality of spinal cord injured men is better when obtained by vibratory stimulation versus electroejaculation.

    Science.gov (United States)

    Brackett, N L; Padron, O F; Lynne, C M

    1997-01-01

    Most spinal cord injured men require assisted ejaculation procedures to obtain semen, and the majority can achieve this result by vibratory stimulation or electroejaculation. We determined if semen obtained by vibratory stimulation differed in quality from that obtained by electroejaculation. Between subjects and within subjects designs were used. Of 77 spinal cord injured men 23 underwent vibratory stimulation only, 44 electroejaculation only and 10 both procedures. Antegrade, retrograde and total ejaculates were analyzed in each subject for total sperm count, percent motile sperm and percent sperm with rapid linear motion. With vibratory stimulation compared to electroejaculation the percent motile sperm and percent sperm with rapid linear motion were significantly greater, whereas total sperm count was similar, in the antegrade specimens and total ejaculates. This finding was true for different groups of subjects as well as within a group of the same subjects. Semen obtained by vibratory stimulation is of better quality than that obtained by electroejaculation. In medical practices that include assisted ejaculation of spinal cord injured men, we recommend obtaining a specimen by vibratory stimulation. If that method fails electroejaculation should be performed.

  5. Dynamic of the volcanic activity of La Soufrière volcano (Guadeloupe, Lesser Antillles): Evidence for shallow fluid seismic sources

    Science.gov (United States)

    Ucciani, G.; Beauducel, F.; Bouin, M. P.; Nercessian, A.

    2015-12-01

    La Soufrière is one of the many hazardous volcanoes in the inner arc of Lesser Antilles. Located South of Basse-Terre island, it is the only active volcano of the Guadeloupe archipelago. Since the last significant magmatic eruption in 1535 AD, the activity has been exculsively phreatic. Since 1992 and the abrupt renewal of seismic and fumarollic activities, the Guadeloupe Volcanological and Seismological Observatory (OVSG-IPGP) has recorded a progressive increasing of seismicity and degassing that led scientists and authorities to set the alert level ``Vigilance'' and hold it until today. According to the recent geophysical, geochemical and geological studies, the current volcanic activity of la Soufrière volcano seems to be exclusively associated to the hydrothermal system, while the link with seismic activity is still poorly studied. In this context of possible pre-eruptive unrest, we investigated the spatial and temporal variations of the seismicity recorded between 1981 and 2013. From a consistent seismological framework coupling spectral, statistical, signal processing, clustering, and inverse problems methods, we demonstrate that this seismicity is largely generated by shallow hydrothermal fluid sources located in a complex plumbing system. Spatial variations of Vp/Vs ratio and B-value in seismogenic structures allow us to document three main seismic zones associated to : (1) migration of magmatic gas, (2) the storage and mixing of underground water and gas and (3) the shallow migration of hydrothermal fluids in high fractured and heterogeneous system. Waveform analysis revealed a low number of significant families consistent with fracturing process, and the temporal evolution of multiplet activities highlighted several variations associated with surface manifestations and brutal dynamic changes after major local tectonic earthquakes of Les Saintes (21 November 2004, Mw=6.3), its main aftershock (14 February 2005, Mw=5.7) and the last major earthquake of la

  6. Seismic imaging of the 2001 Bhuj Mw7.7 earthquake source zone: b-value, fractal dimension and seismic velocity tomography studies

    Science.gov (United States)

    Mandal, Prantik; Rodkin, Mikhail V.

    2011-11-01

    We use precisely located aftershocks of the 2001 Mw7.7 Bhuj earthquake (2001-2009) to explore the structure of the Kachchh seismic zone by mapping the 3-D distributions of b-value, fractal dimension (D) and seismic velocities. From frequency-magnitude analysis, we find that the catalog is complete above Mw = 3.0. Thus, we analyze 2159 aftershocks with Mw ≥ 3.0 to estimate the 3-D distribution of b-value and fractal dimensions using maximum-likelihood and spatial correlation dimension approaches, respectively. Our results show an area of high b-, D- and Vp/Vs ratio values at 15-35 km depth in the main rupture zone (MRZ), while relatively low b- and D values characterize the surrounding rigid regions and Gedi fault (GF) zone. We propose that higher material heterogeneities in the vicinity of the MRZ and/or circulation of deep aqueous fluid/volatile CO 2 is the main cause of the increased b-, D- and Vp/Vs ratio values at 15-35 km depth. Seismic velocity images also show some low velocity zones continuing in to the deep lower crust, supporting the existence of circulation of deep aqueous fluid / volatile CO 2 in the region (probably released from the eclogitasation of olivine rich lower crustal rocks). The presence of number of high and low velocity patches further reveals the heterogeneous and fractured nature of the MRZ. Interestingly, we observe that Aki (1981)'s relation (D = 2b) is not valid for the spatial b-D correlation of the events in the GF (D 2 = 1.2b) zone. However, the events in the MRZ (D 2 = 1.7b) show a fair agreement with the D = 2b relationship while the earthquakes associated with the remaining parts of the aftershock zone (D 2 = 1.95b) show a strong correlation with the Aki (1981)'s relationship. Thus, we infer that the remaining parts of the aftershock zone are probably behaving like locked un-ruptured zones, where larger stresses accumulate. We also propose that deep fluid involvement may play a key role in generating seismic activity in the

  7. Site Characterization of the Source Physics Experiment Phase II Location Using Seismic Reflection Data

    Energy Technology Data Exchange (ETDEWEB)

    Sexton, Emily [Washington Univ., St. Louis, MO (United States); Snelson, Catherine M [NSTec; Chipman, Veraun D [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Emer, Dudley [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); White, Bob [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Emmit, Ryan [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Wright, Al [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Drellack, Sigmund [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Huckins-Gang, Heather [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Mercadante, Jennifer [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Floyd, Michael [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); McGowin, Chris [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Cothrun, Chris [Univ. of Nevada, Las Vegas, NV (United States); Bonal, Nedra [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2013-12-05

    An objective of the Source Physics Experiment (SPE) is to identify low-yield nuclear explosions from a regional distance. Low-yield nuclear explosions can often be difficult to discriminate among the clutter of natural and man-made explosive events (e.g., earthquakes and mine blasts). The SPE is broken into three phases. Phase I has provided the first of the physics-based data to test the empirical models that have been used to discriminate nuclear events. The Phase I series of tests were placed within a highly fractured granite body. The evolution of the project has led to development of Phase II, to be placed within the opposite end member of geology, an alluvium environment, thereby increasing the database of waveforms to build upon in the discrimination models. Both the granite and alluvium sites have hosted nearby nuclear tests, which provide comparisons for the chemical test data. Phase III of the SPE is yet to be determined.

  8. Tsunami hazard assessment in El Salvador, Central America, from seismic sources through flooding numerical models.

    Science.gov (United States)

    Álvarez-Gómez, J. A.; Aniel-Quiroga, Í.; Gutiérrez-Gutiérrez, O. Q.; Larreynaga, J.; González, M.; Castro, M.; Gavidia, F.; Aguirre-Ayerbe, I.; González-Riancho, P.; Carreño, E.

    2013-11-01

    El Salvador is the smallest and most densely populated country in Central America; its coast has an approximate length of 320 km, 29 municipalities and more than 700 000 inhabitants. In El Salvador there were 15 recorded tsunamis between 1859 and 2012, 3 of them causing damages and resulting in hundreds of victims. Hazard assessment is commonly based on propagation numerical models for earthquake-generated tsunamis and can be approached through both probabilistic and deterministic methods. A deterministic approximation has been applied in this study as it provides essential information for coastal planning and management. The objective of the research was twofold: on the one hand the characterization of the threat over the entire coast of El Salvador, and on the other the computation of flooding maps for the three main localities of the Salvadorian coast. For the latter we developed high-resolution flooding models. For the former, due to the extension of the coastal area, we computed maximum elevation maps, and from the elevation in the near shore we computed an estimation of the run-up and the flooded area using empirical relations. We have considered local sources located in the Middle America Trench, characterized seismotectonically, and distant sources in the rest of Pacific Basin, using historical and recent earthquakes and tsunamis. We used a hybrid finite differences-finite volumes numerical model in this work, based on the linear and non-linear shallow water equations, to simulate a total of 24 earthquake-generated tsunami scenarios. Our results show that at the western Salvadorian coast, run-up values higher than 5 m are common, while in the eastern area, approximately from La Libertad to the Gulf of Fonseca, the run-up values are lower. The more exposed areas to flooding are the lowlands in the Lempa River delta and the Barra de Santiago Western Plains. The results of the empirical approximation used for the whole country are similar to the results

  9. Vibratory device for taking ocean floor sediment cores

    Energy Technology Data Exchange (ETDEWEB)

    Edigariav, Z.P.; Kudinov, E.I.; Sukhov, V.E.

    1973-04-04

    The present invention relates to devices for taking sediment cores from the ocean floor. It consists in a vibratory device, comprising a string of pipe, a vibrator disposed on the string of pipe for sinking the pipe into the ocean floor, an arrangement for providing for periodical engagement and disengagement of the vibrator with the string of pipe, a hoist providing for periodical displacement of the vibrator, which is originally disposed on the lower portion of the string of pipe, up the string as the latter is being sunk into the ocean floor, and operatively coupled with the engaging arrangement. A piston is freely displaceable in the string of pipe and fixed relative to the ocean floor when the pipe is being sunk, to retain the ocean floor sediments in the pipe. The core of sediment is pressed against the piston under the action of hydrostatic and atmospheric pressures. A system is provided for stabilizing the device consisting of a load platform, a float, and guide cables. (6 claims)

  10. OpenSWPC: an open-source integrated parallel simulation code for modeling seismic wave propagation in 3D heterogeneous viscoelastic media

    Science.gov (United States)

    Maeda, Takuto; Takemura, Shunsuke; Furumura, Takashi

    2017-07-01

    We have developed an open-source software package, Open-source Seismic Wave Propagation Code (OpenSWPC), for parallel numerical simulations of seismic wave propagation in 3D and 2D (P-SV and SH) viscoelastic media based on the finite difference method in local-to-regional scales. This code is equipped with a frequency-independent attenuation model based on the generalized Zener body and an efficient perfectly matched layer for absorbing boundary condition. A hybrid-style programming using OpenMP and the Message Passing Interface (MPI) is adopted for efficient parallel computation. OpenSWPC has wide applicability for seismological studies and great portability to allowing excellent performance from PC clusters to supercomputers. Without modifying the code, users can conduct seismic wave propagation simulations using their own velocity structure models and the necessary source representations by specifying them in an input parameter file. The code has various modes for different types of velocity structure model input and different source representations such as single force, moment tensor and plane-wave incidence, which can easily be selected via the input parameters. Widely used binary data formats, the Network Common Data Form (NetCDF) and the Seismic Analysis Code (SAC) are adopted for the input of the heterogeneous structure model and the outputs of the simulation results, so users can easily handle the input/output datasets. All codes are written in Fortran 2003 and are available with detailed documents in a public repository.[Figure not available: see fulltext.

  11. Seismic velocity structure and microearthquake source properties at The Geysers, California, geothermal area

    Energy Technology Data Exchange (ETDEWEB)

    O' Connell, D.R.

    1986-12-01

    The method of progressive hypocenter-velocity inversion has been extended to incorporate S-wave arrival time data and to estimate S-wave velocities in addition to P-wave velocities. S-wave data to progressive inversion does not completely eliminate hypocenter-velocity tradeoffs, but they are substantially reduced. Results of a P and S-wave progressive hypocenter-velocity inversion at The Geysers show that the top of the steam reservoir is clearly defined by a large decrease of V/sub p//V/sub s/ at the condensation zone-production zone contact. The depth interval of maximum steam production coincides with minimum observed V/sub p//V/sub s/, and V/sub p//V/sub s/ increses below the shallow primary production zone suggesting that reservoir rock becomes more fluid saturated. The moment tensor inversion method was applied to three microearthquakes at The Geysers. Estimated principal stress orientations were comparable to those estimated using P-wave firstmotions as constraints. Well constrained principal stress orientations were obtained for one event for which the 17 P-first motions could not distinguish between normal-slip and strike-slip mechanisms. The moment tensor estimates of principal stress orientations were obtained using far fewer stations than required for first-motion focal mechanism solutions. The three focal mechanisms obtained here support the hypothesis that focal mechanisms are a function of depth at The Geysers. Progressive inversion as developed here and the moment tensor inversion method provide a complete approach for determining earthquake locations, P and S-wave velocity structure, and earthquake source mechanisms.

  12. Acoustic and seismic imaging of the Adra Fault (NE Alboran Sea: in search of the source of the 1910 Adra earthquake

    Directory of Open Access Journals (Sweden)

    E. Gràcia

    2012-11-01

    Full Text Available Recently acquired swath-bathymetry data and high-resolution seismic reflection profiles offshore Adra (Almería, Spain reveal the surficial expression of a NW–SE trending 20 km-long fault, which we termed the Adra Fault. Seismic imaging across the structure depicts a sub-vertical fault reaching the seafloor surface and slightly dipping to the NE showing an along-axis structural variability. Our new data suggest normal displacement of the uppermost units with probably a lateral component. Radiocarbon dating of a gravity core located in the area indicates that seafloor sediments are of Holocene age, suggesting present-day tectonic activity. The NE Alboran Sea area is characterized by significant low-magnitude earthquakes and by historical records of moderate magnitude, such as the Mw = 6.1 1910 Adra Earthquake. The location, dimension and kinematics of the Adra Fault agree with the fault solution and magnitude of the 1910 Adra Earthquake, whose moment tensor analysis indicates normal-dextral motion. The fault seismic parameters indicate that the Adra Fault is a potential source of large magnitude (Mw ≤ 6.5 earthquakes, which represents an unreported seismic hazard for the neighbouring coastal areas.

  13. Analysis of post-blasting source mechanisms of mining-induced seismic events in Rudna copper mine, Poland

    Directory of Open Access Journals (Sweden)

    Caputa Alicja

    2015-10-01

    Full Text Available The exploitation of georesources by underground mining can be responsible for seismic activity in areas considered aseismic. Since strong seismic events are connected with rockburst hazard, it is a continuous requirement to reduce seismic risk. One of the most effective methods to do so is blasting in potentially hazardous mining panels. In this way, small to moderate tremors are provoked and stress accumulation is substantially reduced. In this paper we present an analysis of post-blasting events using Full Moment Tensor (MT inversion at the Rudna mine, Poland, underground seismic network. In addition, we describe the problems we faced when analyzing seismic signals. Our studies show that focal mechanisms for events that occurred after blasts exhibit common features in the MT solution. The strong isotropic and small Double Couple (DC component of the MT, indicate that these events were provoked by detonations. On the other hand, post-blasting MT is considerably different than the MT obtained for strong mining events. We believe that seismological analysis of provoked and unprovoked events can be a very useful tool in confirming the effectiveness of blasting in seismic hazard reduction in mining areas.

  14. A high-efficiency self-powered wireless sensor node for monitoring concerning vibratory events

    Science.gov (United States)

    Xu, Dacheng; Li, Suiqiong; Li, Mengyang; Xie, Danpeng; Dong, Chuan; Li, Xinxin

    2017-09-01

    This paper presents a self-powered wireless alarming sensor node (SWASN), which was designed to monitor the occurrence of concerning vibratory events. The major components of the sensor node include a vibration-threshold-triggered energy harvester (VTTEH) that powers the sensor node, a dual threshold voltage control circuit (DTVCC) for power management and a radio frequency (RF) signal transmitting module. The VTTEH generates significant electric energy only when the input vibration reaches certain amplitude. Thus, the VTTEH serves as both the power source and the vibration-event-sensing element for the sensor node. The DTVCC was specifically designed to utilize the limited power supply from the VTTEH to operate the sensor node. Constructed with only voltage detectors and MOSFETs, the DTVCC achieved low power consumption, which was 65% lower compared with the power management circuit designed in our previous work. Meanwhile, a RF transmit circuit was constructed based on the commercially available CC1110-F32 wireless transceiver chip and a compact planar antenna was designed to improve the signal transmission distance. The sensor node was fabricated and was characterized both in the laboratory and in the field. Experimental results showed that the SWASN could automatically send out alarming signals when the simulated concerning event occurred. The waiting time between two consecutive transmission periods is less than 125 s and the transmission distance can reach 1.31 km. The SWASN will have broad applications in field surveillances.

  15. Seismicity around the source areas of the 1946 Nankai and the 1944 Tonankai earthquakes detected from data recorded at DONET stations

    Science.gov (United States)

    Suzuki, K.; Kamiya, S.; Takahashi, N.

    2016-12-01

    The Japan Agency for Marine-Earth Science and Technology (JAMSTEC) installed DONET (Dense Oceanfloor Network System for Earthquakes and Tsunamis) off the Kii Peninsula, southwest of Japan, to monitor earthquakes and tsunamis. Stations of DONET1, which are distributed in Kumano-nada, and DONET2, which are distributed off Muroto, were installed by August 2011 and April 2016, respectively. After the installation of all of the 51 stations, DONET was transferred to National Research Institute for Earth Science and Disaster Resilience (NIED). NIED and JAMSTEC have now corroborated in the operation of DONET since April 2016. To investigate the seismicity around the source areas of the 1946 Nankai and the 1944 Tonankai earthquakes, we detected earthquakes from the records of the broadband seismometers installed to DONET. Because DONET stations are apart from land stations, we can detect smaller earthquakes than by using only land stations. It is important for understanding the stress state and seismogenic mechanism to monitoring the spatial-temporal seismicity change. In this study we purpose to evaluate to the seismicity around the source areas of the Nankai and the Tonankai earthquakes by using our earthquake catalogue. The frequency-magnitude relationships of earthquakes in the areas of DONET1&2 had an almost constant slope of about -1 for earthquakes of ML larger than 1.5 and 2.5, satisfying the Gutenberg-Richter law, and the slope of smaller earthquakes approached 0, reflecting the detection limits. While the most of the earthquakes occurred in the aftershock area of the 2004 off the Kii Peninsula earthquakes, very limited activity was detected in the source region of the Nankai and Tonankai earthquake except for the large earthquake (MJMA = 6.5) on 1st April 2016 and its aftershocks. We will evaluate the detection limit of the earthquake in more detail and investigate the spatial-temporal seismicity change with waiting the data store.

  16. Seismic tomography model reveals mantle magma sources of recent volcanic activity at El Hierro Island (Canary Islands, Spain)

    Science.gov (United States)

    García-Yeguas, Araceli; Ibáñez, Jesús M.; Koulakov, Ivan; Jakovlev, Andrey; Romero-Ruiz, M. Carmen; Prudencio, Janire

    2014-12-01

    We present a 3-D model of P and S velocities beneath El Hierro Island, constructed using the traveltime data of more than 13 000 local earthquakes recorded by the Instituto Geográfico Nacional (IGN, Spain) in the period from 2011 July to 2012 September. The velocity models were performed using the LOTOS code for iterative passive source tomography. The results of inversion were thoroughly verified using different resolution and robustness tests. The results reveal that the majority of the onshore area of El Hierro is associated with a high-velocity anomaly observed down to 10-12-km depth. This anomaly is interpreted as the accumulation of solid igneous rocks erupted during the last 1 Myr and intrusive magmatic bodies. Below this high-velocity pattern, we observe a low-velocity anomaly, interpreted as a batch of magma coming from the mantle located beneath El Hierro. The boundary between the low- and high-velocity anomalies is marked by a prominent seismicity cluster, thought to represent anomalous stresses due to the interaction of the batch of magma with crust material. The areas of recent eruptions, Orchilla and La Restinga, are associated with low-velocity anomalies surrounding the main high-velocity block. These eruptions took place around the island where the crust is much weaker than the onshore area and where the melted material cannot penetrate. These results put constraints on the geological model that could explain the origin of the volcanism in oceanic islands, such as in the Canaries, which is not yet clearly understood.

  17. Interference of Overlapping Insect Vibratory Communication Signals: An Eushistus heros Model.

    Directory of Open Access Journals (Sweden)

    Andrej Čokl

    Full Text Available Plants limit the range of insect substrate-borne vibratory communication by their architecture and mechanical properties that change transmitted signal time, amplitude and frequency characteristics. Stinkbugs gain higher signal-to-noise ratio and increase communication distance by emitting narrowband low frequency vibratory signals that are tuned with transmission properties of plants. The objective of the present study was to investigate hitherto overlooked consequences of duetting with mutually overlapped narrowband vibratory signals. The overlapped vibrations of the model stinkbug species Eushistus heros, produced naturally or induced artificially on different plants, have been analysed. They represent female and male strategies to preserve information within a complex masked signal. The brown stinkbugs E. heros communicate with species and gender specific vibratory signals that constitute characteristic duets in the calling, courtship and rivalry phases of mating behaviour. The calling female pulse overlaps the male vibratory response when the latency of the latter is shorter than the duration of the female triggering signal or when the male response does not inhibit the following female pulse. Overlapping of signals induces interference that changes their amplitude pattern to a sequence of regularly repeated pulses in which their duration and the difference between frequencies of overlapped vibrations are related inversely. Interference does not occur in overlapped narrow band female calling pulses and broadband male courtship pulse trains. In a duet with overlapped signals females and males change time parameters and increase the frequency difference between signals by changing the frequency level and frequency modulation pattern of their calls.

  18. Change Detection via Cross-Borehole and VSP Seismic Surveys for the Source Physics Experiments (SPE) at the Nevada National Security Site (NNSS)

    Science.gov (United States)

    Knox, H. A.; Abbott, R. E.; Bonal, N. D.; Aldridge, D. F.; Preston, L. A.; Ober, C.

    2012-12-01

    In support of the Source Physics Experiment (SPE) at the Nevada National Security Site (NNSS), we have conducted two cross-borehole seismic experiments in the Climax Stock. The first experiment was conducted prior to the third shot in this multi-detonation program using two available boreholes and the shot hole, while the second experiment was conducted after the shot using four of the available boreholes. The first study focused on developing a well-characterized 2D pre-explosion Vp model including two VSPs and a seismic refraction survey, as well as quantifying baseline waveform similarity at reoccupied sites. This was accomplished by recording both "sparker" and accelerated weight drop sources on a hydrophone string and surface geophones. In total more than 18,500 unique source-receiver pairs were acquired during this testing. In the second experiment, we reacquired aproximately 8,800 source-receiver pairs and performed a cross-line survey allowing for a 3D post-explosion Vp model. The data acquired from the reoccupied sites was processed using cross-correlation methods and change detection methodologies, including comparison of the tomographic images. The survey design and subsequent processing provided an opportunity to investigate seismic wave propagation through damaged rock. We also performed full waveform forward modelling for a granitic body hosting a perched aquifer. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  19. The effect of penile vibratory stimulation on male fertility potential, spasticity and neurogenic detrusor overactivity in spinal cord lesioned individuals

    DEFF Research Database (Denmark)

    Biering-Sørensen, F; Læssøe, Line; Sønksen, J

    2005-01-01

    Present the possibility for treatment of male infertility, spasticity, and neurogenic detrusor overactivity in spinal cord lesioned (SCL) individuals with penile vibratory stimulation (PVS).......Present the possibility for treatment of male infertility, spasticity, and neurogenic detrusor overactivity in spinal cord lesioned (SCL) individuals with penile vibratory stimulation (PVS)....

  20. Back-Projection Imaging of extended pre-, co-, and post-eruptive seismic sources through multiple eruption cycles at Jefe Geyser, El Tatio Geyser Field, Chile

    Science.gov (United States)

    Kelly, C. L.

    2016-12-01

    El Tatio Geyser Field on the western flanks of the Andes Mountains in northern Chile at 4300 m elevation is the 3rd largest geyser field in the world. The three basins that comprise the field contain over 100 accessible hydrothermal features, and its relatively non-pristine condition makes it an ideal place to perform minimally invasive geophysical experiments. We deployed a dense array of 51 L-28 3-component geophones (1-10 meter spacing, corner frequency 4.5 Hz, 1000 Hz sampling rate), and 6 Trillium 120 broadband seismometers (2-20 meter spacing, long period corner 120 s, 500 Hz sampling rate) in a 50 x 50 m grid in the central Upper Geyser Basin (the largest basin in area at 5 x 5 km) during October 2012 as part of a collaborative effort to study hydrothermal system dynamics between U.C. Berkeley; Stanford University; the University of Chile, Santiago; the University of Tokyo; and the USGS. The array was designed to target El Jefe Geyser, an easily accessible columnar geyser with a consistent periodic eruption cycle of 129 s. The 2-week seismic deployment recorded approximately 2500 eruptions that we use to study the evolution of seismic source locations throughout an eruption and over multiple eruption cycles. We use a new back-projection processing technique to locate geyser signals, which tend to be harmonic and diffuse in nature. We obtain Vp and Vs from ambient-field tomography and use these velocities to correlate and back-project seismic signals from all available receiver-pairs to potential subsurface source locations assuming straight-line raypaths. We then create 4D time-lapse images of individual and concurrent geyser sources. We use spectral observations of long duration sources to target specific seismic observations (i.e., high or low frequency bands) and apply polarization filtering to isolate P and S phases during different stages of the eruption cycle. We use our results to evaluate changes in source distributions before, during and after

  1. Marine and land active-source seismic imaging of mid-Miocene to Holocene-aged faulting near geothermal prospects at Pyramid Lake, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Eisses, A.; Kell, A.; Kent, G. [UNR; Driscoll, N. [UCSD; Karlin, R.; Baskin, R. [USGS; Louie, J. [UNR; Pullammanappallil, S. [Optim

    2016-08-01

    Amy Eisses, Annie Kell, Graham Kent, Neal Driscoll, Robert Karlin, Rob Baskin, John Louie, and Satish Pullammanappallil, 2011, Marine and land active-source seismic imaging of mid-Miocene to Holocene-aged faulting near geothermal prospects at Pyramid Lake, Nevada: Geothermal Resources Council Transactions, 35, 7 pp. Preprint at http://crack.seismo.unr.edu/geothermal/Eisses-GRCpaper-sm.pdf The Pyramid Lake fault zone lies within a vitally important area of the northern Walker Lane where not only can transtension can be studied through a complex arrangement of strike-slip and normal faults but also geothermal activity can be examined in the extensional regime for productivity. This study used advanced and economical seismic methods in attempt to develop the Paiute Tribe’s geothermal reservoir and to expand upon the tectonics and earthquake hazard knowledge of the area. 500 line-kilometers of marine CHIRP data were collected on Pyramid Lake combined with 27 kilometers of vibrator seismic on-land data from the northwest side of the basin were collected in 2010 that highlighted two distinct phases of faulting. Preliminary results suggest that the geothermal fluids in the area are controlled by the late Pleistoceneto Holocene-aged faults and not through the mid-Miocene-aged conduits as originally hypothesized.

  2. Six-degree-of-freedom near-source seismic motions II: examples of real seismogram analysis and S-wave velocity retrieval

    Czech Academy of Sciences Publication Activity Database

    Brokešová, J.; Málek, Jiří

    2015-01-01

    Roč. 19, č. 2 (2015), s. 511-539 ISSN 1383-4649 R&D Projects: GA ČR GAP210/10/0925; GA MŠk LM2010008; GA ČR GAP210/12/2336; GA ČR GA15-02363S Institutional support: RVO:67985891 Keywords : seismic rotation * near-source region * rotational seismometer * microearthquakes * West Bohemia/Vogtland region * Gulf of Corinth * Katla region Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.550, year: 2015

  3. Automatic classification of sources of volcanic tremors at the Klyuchevskoy volcanic group (Kamchatka) based on the seismic network covariance matrix analysis

    Science.gov (United States)

    Soubestre, Jean; Shapiro, Nikolai M.; Seydoux, Léonard; de Rosny, Julien; Droznin, Dimitry V.; Droznina, Svetlana Ya.; Senyukov, Sergey L.; Gordeev, Evgeny I.

    2017-04-01

    Volcanic tremors may be caused by magma moving through narrow fractures, by fragmentation and pulsation of pressurized fluids within the volcano, or by escape of pressurized steam and gases from fumaroles. They present an important attribute of the volcanic unrest and their detection and characterization is used in volcano monitoring systems. The tremors might be generated within different parts of volcanoes and might characterize different types of volcanic activity. The main goal of the present study is to develop a method of automatic classification of different types (sources) of tremors based on analysis of continuous records of a network of seismographs. The proposed method is based on the analysis of eigenvalues and eigenvectors of the seismic array covariance matrix. First, we followed an approach developed by Seydoux et al. (2016) and analyzed the width of the covariance matrix eigenvalues distribution to detect time periods with strong volcanic tremors. In a next step, we analyzed the frequency-dependent eigenvectors of the covariance matrix. The eigenvectors corresponding to strongest eigenvalues can be used as fingerprints of dominating seismic sources during the period over which the covariance matrix was calculated. We applied the method to the data recorded by the permanent seismic monitoring network composed of 19 stations operated in the vicinity of the Klyuchevskoy group of volcanoes (KVG) located in Kamchatka, Russia. The KVG is composed of 13 stratovolcanoes with 3 of them (Klyuchevskoy, Bezymianny, and Tolbachik) being very active during last decades. In addition, two other active volcanoes, Shiveluch and Kizimen, are located immediately north and south of KVG. This exceptional concentration of active volcanoes provides us with a multiplicity of seismic tremor sources required to validate the method. We used 4.5 years of vertical component records by 19 stations and computed network covariance matrices from day-long windows. We then analyzed

  4. Effects of Lateral Heterogeneities on the Propagation, Scattering, and Attenuation of the Seismic Waves and the Characterization of the Seismic Source

    Science.gov (United States)

    1983-09-30

    can be expressed as FiM-r --fpq Fi(F~r) - ~.cqjqups(S)) (2.2.2) (Burridge and Knopoff, 19641 where Up is the discontinuity in displacement on the fault...location of the source 13 been changed or large discontinuities been introduced in the immediate vicinity, the changes in the solution (especially the...different models derived from the P wave modeling and the first motion polarities are also shown. The Gutenberg earth structure for the continents was

  5. Source duration of stress and water-pressure induced seismicity derived from experimental analysis of P wave pulse width in granite

    Science.gov (United States)

    Masuda, K.

    2013-12-01

    Pulse widths of P waves in granite, measured in the laboratory, were analyzed to investigate source durations of rupture processes for water-pressure induced and stress-induced microseismicity. Much evidence suggests that fluids in the subsurface are intimately linked to faulting processes. Studies of seismicity induced by water injection are thus important for understanding the trigger mechanisms of earthquakes as well as for engineering applications such as hydraulic fracturing of rocks at depth for petroleum extraction. Determining the cause of seismic events is very important in seismology and engineering; however, water-pressure induced seismic events are difficult to distinguish from those induced by purely tectonic stress. To investigate this problem, we analyzed the waveforms of acoustic emissions (AEs) produced in the laboratory by both water-pressure induced and stress-induced microseismicity. We used a cylinder (50 mm in diameter and 100 mm in length) of medium-grained granite. We applied a differential stress of about 70% of fracture strength, to the rock sample under 40 MPa confining pressure and held it constant throughout the experiment. When the primary creep stage and acoustic emissions (AEs) caused by the initial loading had ceased, we injected distilled water into the bottom end of the sample at a constant pressure of 17 MPa until macroscopic fracture occurred. We analysed AE waveforms produced by stress-induced AEs which occurred before the water-injection and by water-pressure induced AEs which occurred after the water-injection. Pulse widths were measured from the waveform traces plotted from the digital data. To investigate the source duration of the rupture process, we estimated the pulse width at the source and normalized by event magnitude to obtain a scaled pulse width at the source. After the effects of event size and hypocentral distance were removed from observed pulse widths, the ratio of the scaled source durations of water

  6. Theoretical and experimental study of the transport of granular materials by inclined vibratory conveyors

    NARCIS (Netherlands)

    Sloot, E.M.; Sloot, E.M.; Kruyt, Nicolaas P.

    1996-01-01

    A theoretical and experimental study was made of the conveying speed with which granular materials are transported by vibratory conveyors. The basic assumption made is that the layer of granular material can be considered as a point mass. The theory incorporates rest, slide, and flight phases of the

  7. Considerations Concerning the Dynamics of Vibratory Mills Used in Powders’ Mechanical Milling Process

    Directory of Open Access Journals (Sweden)

    Radu Panaitescu-Liess

    2010-01-01

    Full Text Available Dynamic mechanical milling process in a powder mill was studied by analyzing the vibratory effects of vibration and shock phenomena on the material microstructure ground. During the milling process, there were noticed both distinct modes of ball motion: the one generated by the periodic vibration and the one produced by chaotic vibration.

  8. Comparison of Axial Capacity of Vibratory-Driven Piles to Impact-Driven Piles.

    Science.gov (United States)

    1987-09-01

    vibratory-driven process results in less compacatiori at the pile tip, thus lowering the tip capacity. Hunter and Davisson (1969), in their...Loading Tests," US Army Engineer District, Little Rock, Ark. Hunter, A. A., and Davisson , M. T. (1969). "Measurement of Pile Load Transfer," Performance

  9. ANALYSIS OF VIBRATORY PROTECTION SYSTEM VIBRATION DURING HARMONIC AND POLYHARMONIC EXCITATIONS

    Directory of Open Access Journals (Sweden)

    T. N. Mikulik

    2011-01-01

    Full Text Available The paper considers a mathematical model of local «driver-seat» system and an algorithm for vibratory loading formation at external actions. Results of the investigations on the system vibration according to minimum vibration acceleration depending on transfer force factor acting on the seat and a vibration isolation factor are presented in the paper.

  10. Wave radiation from vibratory and impact pile driving in a layered acousto-elastic medium

    NARCIS (Netherlands)

    Tsouvalas, A.; Metrikine, A.

    2014-01-01

    A steel monopile is the most common foundation type of a wind turbine installed offshore and is driven into place with the help of vibratory or impact hammers. Underwater noise generated during the installation of steel monopiles has recently received considerable attention from international

  11. Assessment of Penile Vibratory Stimulation as a Management Strategy in Men with Secondary Retarded Orgasm

    Science.gov (United States)

    Nelson, Christian J.; Ahmed, Absaar; Valenzuela, Rolando; Parker, Marilyn; Mulhall, John P.

    2016-01-01

    OBJECTIVES To evaluate the effectiveness of penile vibratory stimulation for the management of retarded orgasm. Retarded orgasm, a condition characterized by difficulty achieving orgasm and ejaculation, is one of the most recalcitrant of the male sexual dysfunctions. Currently, no evidence-based treatments have been proven to ameliorate this condition. METHODS Men who had a complete inability to achieve an orgasm during sexual relations in the previous 3 months were instructed in the use of penile vibratory stimulation. The men’s responses were measured by self-report of orgasm function and using the orgasm and satisfaction domains of the International Index of Erectile Function. The responses were assessed at baseline (admission into the study) and at 3 and 6 months. RESULTS A total of 36 men met the inclusion criteria, and 72% reported the restoration of orgasm. These responders reported that orgasm during sexual relations occurred 62% of the time. A statistically and clinically significant increase occurred in the orgasm and satisfaction domains of the International Index of Erectile Function between the baseline visit and the 3-month follow-up visit. These gains were sustained at 6 months. CONCLUSIONS Penile vibratory stimulation is an effective treatment for retarded orgasm. Penile vibratory stimulation should be integrated into current cognitive-behavioral sex therapy techniques to achieve maximal effectiveness and satisfaction. PMID:17382163

  12. Using detrended fluctuation analysis (DFA) to analyze whether vibratory insoles enhance balance stability for elderly fallers.

    Science.gov (United States)

    Wang, Chien-Chih; Yang, Wen-Hung

    2012-01-01

    Falls are a common and devastating problem among elderly people. In a previous study, vibratory insoles were developed to improve postural stability for elderly fallers. To verify the effects of vibratory insoles, a two-stage experiment was conducted to collect center of pressure (COP) signals from 26 elderly fallers and 16 healthy young subjects while standing still. The DFA is used to analyze the behavior of different time-series data obtained from the trajectory of COP. Postural stability was compared by the DFA scaling exponent between a control condition (before using vibratory insoles) and a vibration condition (after using vibratory insoles). For elderly fallers, DFA scaling exponents 95% confidence interval were [1.434, 1.547] and [1.329, 1.451] under control and vibration conditions in the anteroposterior (AP) direction, respectively. The experimental results revealed that temporary stimuli of appropriate amplitude produced by vibration insoles enhanced postural stability in elderly fallers and was more obvious in the AP direction. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  13. Control of Vibratory Energy Harvesters in the Presence of Nonlinearities and Power-Flow Constraints

    Science.gov (United States)

    Cassidy, Ian L.

    Over the past decade, a significant amount of research activity has been devoted to developing electromechanical systems that can convert ambient mechanical vibrations into usable electric power. Such systems, referred to as vibratory energy harvesters, have a number of useful of applications, ranging in scale from self-powered wireless sensors for structural health monitoring in bridges and buildings to energy harvesting from ocean waves. One of the most challenging aspects of this technology concerns the efficient extraction and transmission of power from transducer to storage. Maximizing the rate of power extraction from vibratory energy harvesters is further complicated by the stochastic nature of the disturbance. The primary purpose of this dissertation is to develop feedback control algorithms which optimize the average power generated from stochastically-excited vibratory energy harvesters. This dissertation will illustrate the performance of various controllers using two vibratory energy harvesting systems: an electromagnetic transducer embedded within a flexible structure, and a piezoelectric bimorph cantilever beam. Compared with piezoelectric systems, large-scale electromagnetic systems have received much less attention in the literature despite their ability to generate power at the watt--kilowatt scale. Motivated by this observation, the first part of this dissertation focuses on developing an experimentally validated predictive model of an actively controlled electromagnetic transducer. Following this experimental analysis, linear-quadratic-Gaussian control theory is used to compute unconstrained state feedback controllers for two ideal vibratory energy harvesting systems. This theory is then augmented to account for competing objectives, nonlinearities in the harvester dynamics, and non-quadratic transmission loss models in the electronics. In many vibratory energy harvesting applications, employing a bi-directional power electronic drive to actively

  14. Reproductive Biology, Mating Behavior, and Vibratory Communication of the Brown-Winged Stink Bug, Edessa meditabunda (Fabr. (Heteroptera: Pentatomidae

    Directory of Open Access Journals (Sweden)

    Cleonor Cavalcante A. Silva

    2012-01-01

    Full Text Available We describe different aspects of the reproductive biology, mating behavior, and vibratory communication of the pentatomid Edessa meditabunda (Fabr.. This species shows lower copulation frequency and reproductive potential with longer sexual maturation period compared to other species of pentatomids. Females with multiple mating show increased fecundity when compared with single-mated females and both increased fecundity and reduced longevity when compared with virgin females. Courtship and mating behavior and vibratory signals are typical and similar to what was observed in other species of pentatomids, except that males started the courtship. These results constitute the first paper on biology, behavior, and vibratory communication among species of the subfamily Edessinae.

  15. Combining stress transfer and source directivity: the case-study of the 2012 Emilia seismic sequence, Northern Italy

    Science.gov (United States)

    Convertito, V.; Catalli, F.; Emolo, A.

    2013-12-01

    The Emilia region in the Northern Italy was struck by a seismic sequence that started on May 19, 2012 May with a Mw 3.8 earthquake. It produced about 2100 events during the following month, affecting an area of about 60 km x 30 km elongated in the EW direction. It caused 17 casualties, severe damage to dwellings and forced the closure of several factories. The largest events (Mw 5.6 and 5.4) occurred on 20 May and 29 May, respectively, and were followed by 6 Mw>4.5 earthquakes over the next 2 weeks. We investigate potential mechanisms (both static and dynamic triggering) that may describe the evolution of the sequence. We consider rupture directivity in the dynamic strain field and observe that, for each main earthquake, its related aftershocks and the subsequent large event occurred in an area characterized by higher dynamic strains and corresponding to the dominant rupture direction associated with the previous earthquake. We find that static stress redistribution alone is not capable of explaining the locations of subsequent events and then the evolution of the seismic sequence. We conclude that dynamic triggering played a significant role in driving the sequence. This triggering was also associated with a variation in permeability and a pore pressure increase in an area characterized by a massive presence of fluids.

  16. Extending the inverse scattering series free-surface-multiple-elimination algorithm by accommodating the source property on data with interfering or proximal seismic events

    Science.gov (United States)

    Zhao, Lei; Yang, Jinlong; Weglein, Arthur B.

    2017-12-01

    The inverse scattering series free-surface-multiple-elimination (FSME) algorithm is modified and extended to accommodate the source property-source radiation pattern. That accommodation can provide additional value for the fidelity of the free-surface multiple predictions. The new extended FSME algorithm retains all the merits of the original algorithm, i.e., fully data-driven and with a requirement of no subsurface information. It is tested on a one-dimensional acoustic model with proximal and interfering seismic events, such as interfering primaries and multiples. The results indicate the new extended FSME algorithm can predict more accurate free-surface multiples than methods without the accommodation of the source property if the source has a radiation pattern. This increased effectiveness in prediction contributes to removing free-surface multiples without damaging primaries. It is important in such cases to increase predictive effectiveness because other prediction methods, such as the surface-related-multiple-elimination algorithm, has difficulties and problems in prediction accuracy, and those issues affect efforts to remove multiples through adaptive subtraction. Therefore accommodation of the source property can not only improve the effectiveness of the FSME algorithm, but also extend the method beyond the current algorithm (e.g. improving the internal multiple attenuation algorithm).

  17. Change Detection for Remote Monitoring of Underground Nuclear Testing: Comparison with Seismic and Associated Explosion Source Phenomenological Data

    DEFF Research Database (Denmark)

    Canty, M.; Jahnke, G.; Nielsen, Allan Aasbjerg

    2005-01-01

    detection (MAD) algorithm proposed by Nielsen et. al. (1998). The multispectral data are pre-processed by orthorectification, illumination angle correction and image registration. The technique is applied to historical underground nuclear explosions detonated at the NTS between 1984 and 1992. The detected...... change signals are compared with existing seismic data which include explosion times, locations, yields and depth of burial as well as documented data about surface collapse (subsidence) phenomena like e. g. crater depth and diameter. The comparisons aim at deriving the required detection thresholds...... for the satellite image data sets in terms of explosion size and at deriving possible scaling relations between change signals and the visible explosion effects. This work has been carried out in part within the framework of the Global Monitoring for Security and Stability Network of Excellence (GMOSS) initiated...

  18. IMPACT OF VIBRATORY AND ROTATIONAL SHOT PEENING ONTO SELECTED PROPERTIES OF TITANIUM ALLOY SURFACE LAYER

    Directory of Open Access Journals (Sweden)

    Kazimierz Zaleski

    2014-06-01

    Full Text Available This study presents the results of tests on impact of vibratory and rotational shot peening of the Ti6A12Mo2Cr titanium alloy onto the processed object surface roughness and surface layer microhardness. The external surfaces of ring-shaped samples were shot peened. The preceding process consisted of turning with a cubic boron nitride blade knife. Steel beads, having a diameter of 6 mm, were used as a processing medium. The variable parameters of shot peening were vibrator amplitude and shot peening time. The range of recommended technological parameters for vibratory and rotational shot peening was determined. As a result of shot peening, the surface roughness could be reduced by approximately 4 times and the surface layer could be hardened to the depth of approximately 0.4 mm.

  19. Vibratory-compacted (vipac/sphere-pac) nuclear fuels - a comparison with pelletized nuclear fuels

    Energy Technology Data Exchange (ETDEWEB)

    Chidester, K.; Rubin, J. [Los Alamos National Lab., NM (United States); Thompson, M

    2001-07-01

    In order to achieve the packing densities required for nuclear fuel stability, economy and performance, the fuel material must be densified. This has traditionally been performed by high-temperature sintering. (At one time, fuel densification was investigated using cold/hot swaging. However, this fabrication method has become uncommon.) Alternatively, fuel can be densified by vibratory compaction (VIPAC). During the late 1950's and into the 1970's, in the U.S., vibratory compaction fuel was fabricated and test irradiated to evaluate its applicability compared to the more traditional pelletized fuel for nuclear reactors. These activities were primarily focused on light water reactors (LWR) but some work was performed for fast reactors. This paper attempts to summarize these evaluations and proposes to reconsider VIPAC fuel for future use. (author)

  20. Vibratory sensory testing in acute compartment syndromes: a clinical and experimental study.

    Science.gov (United States)

    Phillips, J H; Mackinnon, S E; Beatty, S E; Dellon, A L; O'Brien, J P

    1987-05-01

    Invasive and noninvasive diagnostic testing was correlated in 11 patients with acute compartmental syndromes of the forearm. The excellent correlation between diminished perception of vibration and increasing compartmental pressure suggested that 256 cycle per second (cps) vibratory stimuli may be useful clinically in determining the appropriate time for surgical intervention in the acute compartmental syndrome. In 12 adult male volunteers, elevated compartment pressures were created in the anterior tibial compartment of the leg. A decrease in perception to 256 cycle per second (cps) vibratory stimulus was the earliest sensory abnormality to occur with elevated tissue compartment pressures. Analysis of variance showed significantly that 256-cps vibration was the most reliable and earliest sensory modality to change at pressures of 35 to 40 mmHg. These clinical and experimental findings support the use of the 256-cps tuning fork as a noninvasive diagnostic test in the evaluation of the patient with suspected acute compartment syndrome.

  1. Seismic imaging with incoherent wavefields

    NARCIS (Netherlands)

    Berkhout, A.J.; Verschuur, D.J.; Blacquière, G.

    2009-01-01

    In blended seismic acquisition incoherent source arrays are used to generate the seismic response. The blended shot records can be directly fed into a shot record migration scheme with a more advanced imaging condition. Blended shot records can also be simulated in the processing phase. In the

  2. Flat lens for seismic waves

    CERN Document Server

    Brule, Stephane; Guenneau, Sebastien

    2016-01-01

    A prerequisite for achieving seismic invisibility is to demonstrate the ability of civil engineers to control seismic waves with artificially structured soils. We carry out large-scale field tests with a structured soil made of a grid consisting of cylindrical and vertical holes in the ground and a low frequency artificial source (< 10 Hz). This allows the identification of a distribution of energy inside the grid, which can be interpreted as the consequence of an effective negative refraction index. Such a flat lens reminiscent of what Veselago and Pendry envisioned for light opens avenues in seismic metamaterials to counteract the most devastating components of seismic signals.

  3. Theoretical and experimental study of the transport of granular materials by inclined vibratory conveyors

    OpenAIRE

    Sloot, E.M.; Kruyt, Nicolaas P.

    1996-01-01

    A theoretical and experimental study was made of the conveying speed with which granular materials are transported by vibratory conveyors. The basic assumption made is that the layer of granular material can be considered as a point mass. The theory incorporates rest, slide, and flight phases of the material. Although the emphasis of this study is on the effect of the inclination (and declination) of the conveyor on the conveying speed, the effects of throw number, friction coefficient and vi...

  4. Infrasound Generation from the HH Seismic Hammer.

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Kyle Richard

    2014-10-01

    The HH Seismic hammer is a large, "weight-drop" source for active source seismic experiments. This system provides a repetitive source that can be stacked for subsurface imaging and exploration studies. Although the seismic hammer was designed for seismological studies it was surmised that it might produce energy in the infrasonic frequency range due to the ground motion generated by the 13 metric ton drop mass. This study demonstrates that the seismic hammer generates a consistent acoustic source that could be used for in-situ sensor characterization, array evaluation and surface-air coupling studies for source characterization.

  5. A new relevant seismic source of the Eastern Betic Shear Zone with Holocene activity: Los Tollos Fault (Murcia, SE Spain).

    Science.gov (United States)

    Insua-Arevalo, Juan M.; Garcia-Mayordomo, Julian; Salazar, Angel; Rodriguez-Escudero, Emilio; Martin-Banda, Raquel; Alvarez-Gomez, Jose A.; Canora, Carolina; Martinez-Diaz, Jose J.

    2014-05-01

    The NW-SE convergence between the Nubian and Eurasian plates in the western Mediterranean (4-5mm/yr) produces a crustal deformation of the southeastern Iberian Peninsula where Late Neogene and Quaternary faulting activity is dominated by a large NE-SW left-lateral strike-slip fault system: the Eastern Betic Shear Zone (EBSZ). The EBSZ is a cortical structure in NNE to NE direction and sigmoid trace that stretches for more than 450 km, and includes, from north to south, the well-known faults of Bajo Segura, Carrascoy, Alhama de Murcia, Palomares and Carboneras. Historically, several of the most destructive seismic events in the Iberian Peninsula, reaching intensities up to IX-X (MSK), have occurred in the area. Those events have been related to the main faults belonging to the EBSZ. Recently, one of the most damaging earthquakes recorded in recent times in Spain, the Lorca earthquake (11/05/2011, Mw 5.2. IEMS98 VII), has been related to the Alhama de Murcia Fault. In this work, we present Los Tollos Fault (LTF) as a new relevant tectonic feature belonging to the Eastern Betic Shear Zone. LTF is located southwest of the Carrascoy Fault, close to densely populated villages (eg: Alhama de Murcia, Totana) and less than 30 km away from downtown Murcia, the largest city of the region with almost half a million inhabitants. This fact highlights the importance of studying the LTF seismogenic potential in order to gain a better picture of the local seismic hazard and risk in the region. The aim of this work is to contribute with new data to parameterize the paleoseismic activity of this active fault in order to be included in future seismic hazard assessments of the area. LTF has been previously mapped as normal fault dipping to the NW. Furthermore, it has also been interpreted as the possible SW extension of the Carrascoy Fault. However, we show that LTF is actually a left-lateral reverse fault dipping to the SE and that it has no apparent connection to the Carrascoy Fault

  6. Long and short wavelengths of Indian Ocean geoid and gravity lows: Mid-to-upper mantle sources, rapid drift and seismicity of Kachchh and Shillong plateau, India

    Science.gov (United States)

    Mishra, D. C.; Ravi Kumar, M.

    2012-10-01

    Spectral analysis of the Indian Ocean geoid low provides depth to the large wavelength sources as ˜1300, ˜700 and 340 km that are supported from the spectral analysis and the modeling of the corresponding large wavelength regional gravity anomaly with negative density contrasts at these levels. The three levels coincide with the sharp changes in the gradient of the seismic velocities related to the olivine-spinel transformation of successively increasing Fe/Mg ratio as depth increases, known as transition zones. The first two segments are supported from continuous wavelet transform analysis of the large wavelength component of the corresponding gravity field. The low density rocks in this section appear to be related to the subducted Indian/Tethyan lithosphere that roll back and drifted southwards after subduction as inferred from tomography experiments. The relatively short wavelength sources of the spectrum of the geoid data at depths of 162 and 85 km suggest sources along the lithosphere - asthenosphere boundary (LAB) under the Indian continent and surrounding oceans, respectively. A low viscosity zone has been envisaged below 660 km discontinuity that may correspond to the low density rocks in this section which is popularly referred to as graveyards of the subducted rocks under geoid lows. The subducted slab is hydrated due to dehydration from metamorphism that causes upwelling in the mid-to-upper mantle which is likely to set in baby plumes. Presence of fluid may transform part of olivine to serpentine further reducing the bulk density of rocks in this section. They would make this region buoyant that appears to be responsible for the Central Indian Ocean Deformation Zone with large scale folding, faulting, seismicity, and high heat flow. The same also appear to be responsible for the rapid drift of the Indian plate. Short wavelength component of the Indian Ocean geoid low reflects most of the surface/shallow tectonics of the region similar to the gravity

  7. Crustal structure beneath the middle-lower Yangtze metallogenic belt in East China: Constraints from passive source seismic experiment on the Mesozoic intra-continental mineralization

    Science.gov (United States)

    Shi, Danian; Lü, Qingtian; Xu, Wenyi; Yan, Jiayong; Zhao, Jinhua; Dong, Shuwen; Chang, Yinfo

    2013-10-01

    To understand the formation and the tectonic process of the Mesozoic middle-lower Yangtze metallogenic belt (YMB), the SinoProbe program deployed a quasi-linear passive source seismic array across the belt. We performed receiver function profiling and measurement of shear-wave splitting parameters with the collected data. Our results show that the Moho depth varies significantly along the profile and that a “mantle uplift” exists right beneath the YMB. We also found that the lower crust of the YMB is different from that of its adjacent areas in structure on the receiver function profile. It possesses seismic anisotropy with direction roughly parallel to the belt. Our SKS/SKKS shear-wave splitting results also show similar belt-parallel azimuthal anisotropy right beneath the YMB. We interpret the seismic anisotropy in the lower crust of the YMB as the result of mineral crystal alignment caused by melting and belt-parallel flow in the Mesozoic ore-forming process. Besides, we observed a nearly south-dipping converter extending from shallow to lower crust beneath the Hefei Basin, which most possibly resulted from the Mesozoic crustal extension. We interpret the “mantle uplift” and the crustal extensional structures to be consequences of asthenospheric upwelling during the Mesozoic ore-forming process. Our results suggest that the lower crust of the YMB was most likely one part of the multi-level metallogenic magma system in the Mesozoic magmatism and mineralization processes, and the formation of the metallogenic belt to be a result much similar to the MASH (Melting, Assimilation, Storage and Homogenization; cf. Hildreth and Moorbath, 1988; Richards, 2003) process. First, the asthenospheric upwelling resulted in a crustal extensional environment; then the melts from the upwelling asthenosphere intruded into the lower crust of the YMB, and assimilation occurred when they mixed with in situ lower crustal materials, which led to the formation of adakitic

  8. METHOD FOR SEISMIC CAPABILITY ASSESSMENT OF THE HIGH VOLTAGE CIRCUIT BREAKERS

    Directory of Open Access Journals (Sweden)

    Ion MANEA

    2009-11-01

    Full Text Available The international norms recommend verification of the circuit breakers seismic capability by tests on seismic platform, but accept assessment through experimental and theoretical combined analysis, too. The paper presents a methodology for seismic capability assessment of the high voltage electric equipments using combined analysis through experimental modal analysis methods. The methodology was applied on some representative types of circuit breakers and disconnecting switchers situated in the working place. The same methodology was applied on a circuit breaker type IO 220 kV/2500A, situated on seismic platform from SC EUROTEST SA Bucharest, after finishing the tests with vibratory signals applied to the base. The equipment, in the same mounting conditions, was tested by means of the present methodology. Were determined the frequency response functions, modal parameters, and theoretical response of some representative points to theoretical vibratory motions applied to base, the same as applied during the direct experimental tests. At the end of paper it is effectuated the comparative analyses of the results obtained through the two methods: direct tests on seismic platform and combined analysis by modal analysis methods.

  9. Modeled temperatures and fluid source distributions for the Mexican subduction zone: Effects of hydrothermal circulation and implications for plate boundary seismic processes

    Science.gov (United States)

    Perry, Matthew; Spinelli, Glenn A.; Wada, Ikuko; He, Jiangheng

    2016-02-01

    In subduction zones, spatial variations in pore fluid pressure are hypothesized to control the sliding behavior of the plate boundary fault. The pressure-temperature paths for subducting material control the distributions of dehydration reactions, a primary control on the pore fluid pressure distribution. Thus, constraining subduction zone temperatures are required to understand the seismic processes along the plate interface. We present thermal models for three margin-perpendicular transects in the Mexican subduction zone. We examine the potential thermal effects of vigorous fluid circulation in a high-permeability aquifer within the basaltic basement of the oceanic crust and compare the results with models that invoke extremely high pore fluid pressures to reduce frictional heating along the megathrust. We combine thermal model results with petrological models to determine the spatial distribution of fluid release from the subducting slab and compare dewatering locations with the locations of seismicity, nonvolcanic tremor, slow-slip events, and low-frequency earthquakes. Simulations including hydrothermal circulation are most consistent with surface heat flux measurements. Hydrothermal circulation has a maximum cooling effect of 180°C. Hydrothermally cooled crust carries water deeper into the subduction zone; fluid release distributions in these models are most consistent with existing geophysical data. Our models predict focused fluid release, which could generate overpressures, coincident with an observed ultraslow layer (USL) and a region of nonvolcanic tremor. Landward of USLs, a downdip decrease in fluid source magnitude could result in the dissipation in overpressure in the oceanic crust without requiring a downdip increase in fault zone permeability, as posited in previous studies.

  10. Seismic Reflection Imaging of the Heat Source of an Ultramafic-Hosted Hydrothermal System (Rainbow, Mid-Atlantic Ridge 36° 10-17'N)

    Science.gov (United States)

    Canales, J. P.; Dunn, R. A.; Sohn, R. A.; Horning, G.; Arai, R.; Paulatto, M.

    2015-12-01

    Most of our understanding of hydrothermal systems and the nature of their heat sources comes from models and observations at fast and intermediate spreading ridges. In these settings, hydrothermal systems are mainly located within the axial zone of a spreading segment, hosted in basaltic rock, and primarily driven by heat extracted from crystallization of crustal melt sills. In contrast, hydrothermal systems at slow-spreading ridges like the Mid-Atlantic Ridge (MAR) show a great variety of venting styles and host-rock lithology, and are located in diverse tectonic settings like axial volcanic ridges, non-transform discontinuities (NTDs), the foot of ridge valley walls, and off-axis inside corner highs. Among MAR systems, the Rainbow hydrothermal field (RHF) stands out as an end-member of this diversity: an ultramafic-hosted system emitting H2 and CH4-rich fluids at high temperatures and high flow rates, which suggests a magmatic heat source despite the lack of evidence for recent volcanism and its location within an NTD with presumably low magma budget. We present 2D multichannel seismic reflection images across the Rainbow massif from the NSF-funded MARINER multidisciplinary geophysical study that reveal, for the first time, the magmatic system driving hydrothermal circulation in an ultramafic setting. Data were acquired in 2013 onboard the RV M. Langseth with an 8-km-long hydrophone streamer. The images have been obtained from pre-stack depth migrations using a regional 3D P-wave velocity model from a coincident controlled-source seismic tomography experiment using ocean bottom seismometers. Our images show a complex magmatic system centered beneath the RHF occupying an areal extent of ~3.7x6 km2, with partially molten sills ranging in depth between ~3.4 km and ~6.9 km below the seafloor. Our data also image high-amplitude dipping reflections within the massif coincident with strong lateral velocity gradients that may arise from detachment fault planes

  11. The making of a fault sources model for seismic hazard assessment: Project SHARE's latest achievements for the Euro-Mediterranean area.

    Science.gov (United States)

    Basili, R.; Kastelic, V.; Valensise, G.

    2011-12-01

    As part of the GEM initiative, the EU Project SHARE (http://www.share-eu.org/) has recently completed a task (Task 3.2) devoted to compiling a database of seismogenic sources for the Euro-Mediterranean area. The final release of the database includes about one thousand records of fully parameterized crustal fault sources for a total mapped length of about 66 thousand kilometers plus parametric data about all Mediterranean subduction zones. The database is being made available to the public through a web-based GIS application (http://diss.rm.ingv.it/SHARE/). With a project area encompassing 53 countries in three different continents and a partnership limitation to 18 institutions, one of the main challenges in the making of such database was to put together a community of experts - many of whom from outside the project - willing to adopt common definitions and standards and to contribute their own original data. These circumstances make it difficult to acknowledge the local scientific legacies and to honor the contributions by each individual expert while preserving the intellectual property of original data. The project area is also renowned for being tectonically very complex, with two major plates (Europe and Africa) and a number of minor plates (Adria, Ionian Sea, Aegean Sea, Anatolia) colliding, extending, subducting, and sliding past each other. Also, the most active plate boundaries are largely located offshore in the Mediterranean and Atlantic Seas. Ongoing tectonic activity affects also continental interiors like the Rhine Graben, Pyrenees, Sicily-Tunisia Channel, or Vrancea, each of these areas being characterized by different tectonic styles and seismic release modes. This varied tectonic setting has been the playground for generations of geoscientists, who often developed different, or even alternative, views that had to be reconciled to fit into the given database framework. This presentation will summarize the various phases in the making of the

  12. Source Parameters for Moderate Earthquakes in the Zagros Mountains with Implications for the Depth Extent of Seismicity

    Energy Technology Data Exchange (ETDEWEB)

    Adams, A; Brazier, R; Nyblade, A; Rodgers, A; Al-Amri, A

    2009-02-23

    Six earthquakes within the Zagros Mountains with magnitudes between 4.9 and 5.7 have been studied to determine their source parameters. These events were selected for study because they were reported in open catalogs to have lower crustal or upper mantle source depths and because they occurred within an area of the Zagros Mountains where crustal velocity structure has been constrained by previous studies. Moment tensor inversion of regional broadband waveforms have been combined with forward modeling of depth phases on short period teleseismic waveforms to constrain source depths and moment tensors. Our results show that all six events nucleated within the upper crust (<11 km depth) and have thrust mechanisms. This finding supports other studies that call into question the existence of lower crustal or mantle events beneath the Zagros Mountains.

  13. Integrated Tsunami Database: simulation and identification of seismic tsunami sources, 3D visualization and post-disaster assessment on the shore

    Science.gov (United States)

    Krivorot'ko, Olga; Kabanikhin, Sergey; Marinin, Igor; Karas, Adel; Khidasheli, David

    2013-04-01

    One of the most important problems of tsunami investigation is the problem of seismic tsunami source reconstruction. Non-profit organization WAPMERR (http://wapmerr.org) has provided a historical database of alleged tsunami sources around the world that obtained with the help of information about seaquakes. WAPMERR also has a database of observations of the tsunami waves in coastal areas. The main idea of presentation consists of determining of the tsunami source parameters using seismic data and observations of the tsunami waves on the shore, and the expansion and refinement of the database of presupposed tsunami sources for operative and accurate prediction of hazards and assessment of risks and consequences. Also we present 3D visualization of real-time tsunami wave propagation and loss assessment, characterizing the nature of the building stock in cities at risk, and monitoring by satellite images using modern GIS technology ITRIS (Integrated Tsunami Research and Information System) developed by WAPMERR and Informap Ltd. The special scientific plug-in components are embedded in a specially developed GIS-type graphic shell for easy data retrieval, visualization and processing. The most suitable physical models related to simulation of tsunamis are based on shallow water equations. We consider the initial-boundary value problem in Ω := {(x,y) ?R2 : x ?(0,Lx ), y ?(0,Ly ), Lx,Ly > 0} for the well-known linear shallow water equations in the Cartesian coordinate system in terms of the liquid flow components in dimensional form Here ?(x,y,t) defines the free water surface vertical displacement, i.e. amplitude of a tsunami wave, q(x,y) is the initial amplitude of a tsunami wave. The lateral boundary is assumed to be a non-reflecting boundary of the domain, that is, it allows the free passage of the propagating waves. Assume that the free surface oscillation data at points (xm, ym) are given as a measured output data from tsunami records: fm(t) := ? (xm, ym,t), (xm

  14. Vibratory stimulation and rectal probe electroejaculation as therapy for patients with spinal cord injury: semen parameters and pregnancy rates.

    Science.gov (United States)

    Nehra, A; Werner, M A; Bastuba, M; Title, C; Oates, R D

    1996-02-01

    The conception rate of patients with spinal cord injuries following penile vibratory stimulation and rectal probe electroejaculation in conjunction with self-insemination, intrauterine insemination or assisted reproductive technique is poorly documented. We reviewed our success rates with penile vibratory stimulation and rectal probe electroejaculation, and the pregnancy rates achieved with self-insemination, intrauterine insemination and assisted reproductive techniques. A total of 78 consecutive patients with spinal cord injuries had a complete neurological examination and was treated initially with penile vibratory stimulation. If unsuccessful, rectal probe electroejaculation was performed to obtain an ejaculate. The ejaculate was then used with self-insemination, intrauterine insemination or assisted reproductive techniques and pregnancies were monitored. Vibratory stimulation was successful in 20 of 37 patients (54%) with a cervical lesion, 14 of 26 (54%) with a lesion at or above T10 and none of 15 when the lesion was below T10. All patients except 2 who elected followup rectal probe electroejaculation had antegrade or retrograde ejaculate. Six patients (7.7%) with extremely poor semen quality were not candidates for assisted fertilization. Of 27 couples who attempted conception 17 were successful (5 self-insemination, 5 intrauterine insemination and 7 assisted reproductive techniques). Penile vibratory stimulation should be used as first line therapy in patients with lesions above T10 while rectal probe electroejaculation should be considered as a second option. Motivated patients can achieve success with self-insemination, intrauterine insemination and assisted reproductive techniques.

  15. Seismic Creep

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seismic creep is the constant or periodic movement on a fault as contrasted with the sudden erupture associated with an earthquake. It is a usually slow deformation...

  16. SourceURL:file://localhost/Users/socquet/Auboulot/congres/socquetAGU2014.doc Geodetic coupling in the North Chile - South Peru seismic gap: new insights from GPS measurements in Peru

    Science.gov (United States)

    Socquet, A.; Cotte, N.; Norabuena, E. O.; Quiroz, W.; Jara, J.; Pina-Valdes, J.; Chlieh, M.; Carrizo, D.; Bejar Pizarro, M.; Metois, M.

    2014-12-01

    SourceURL:file://localhost/Users/socquet/Auboulot/congres/socquetAGU2014.doc The subduction zone at the latitude of the Central Andes did not experience a Mw>8.5 earthquake since the 19thcentury, and forms a ~500km long seismic gap in North Chile - South Peru. Understanding the factors that limit the extent of seismic ruptures is crucial for risk mitigation and for understanding physical processes that govern the behavior of seismogenic faults. It appears crucial to evaluate interseismic coupling and its spatial variation in seismic gaps to assess seismic potential. Recent geodetic studies combining continuous and campaign GPS measurements as well as InSAR measurements showed that the subduction interface in north Chile, was accumulating interseismic elastic strain, likely to rebound into a large megathrust Earthquake. A Mw8.2 earthquake occurred on the 1st of April 2014 in this seismic gap, in front of Pisagua (North Chile), ~150 km south of the Chile-Peru Border. In spite of its already large magnitude, that earthquake was smaller expected in the area, and has most probably increased the stress in the unbroken segments at both edges. Most of accumulated strain remains to be relaxed in the North Chile-South Peru seismic gap. Here we propose to present a first assessment of the interseismic loading in the South Peru part of the seismic gap, at the northern extremity of Pisagua Earthquake, where it is poorly known. In south Peru, over an area of 500 x 250 km, 33 campaign markers have been installed and measured in June 2012. This network has been partially remeasured in June 2013 and April 2014 (after Mw8.2 Pisagua Eaquake). These measurements provide us with an estimate of the Pre-Pisagua-Earthquake coupling, and the co-seismic static displacements. These displacements are combined together with the ones of previous studies that occurred in North Chile and provide a unique and dense velocity field spreading through the Chile Peru border. In particular this provides

  17. Optimization of dynamic source depth for seismic surveys. Part 7; Dynamite shingen no hasshin shindo no saitekika ni tsuite (hyoso kozo no suitei (kusssetsuho jishin tansa oyobi denki denjiho tansa)). 7

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, H.; Murayama, R.; Mitsuhata, Y.; Ishikawa, H. [Japan National Oil Corp., Tokyo (Japan). Technology Research Center

    1996-05-01

    For the improvement of quality of data collected by reflection aided seismic exploration using dynamite as the seismic source, information has to be collected about the surface layer structure before the charge depth is determined. For this purpose, refraction, electric, and electromagnetic exploration methods were tried. In the refraction method, an impactor was used as the seismic source. In the records, the surface wave prevails because vibration was generated on the surface. Analysis was made by the use of the initial travel time tomography. In the electric exploration, a double pole array was used to measure resistivity. The measured data was subjected to a fully automatic inversion for analysis. As the result, it was disclosed that it was useful to know the deep-level structure directly by use of tomographic methods in refraction seismic exploration so as to find the optimum charge level. Furthermore, about the electric and electromagnetic exploration techniques, it was found that these methods can be applied making use of resistivity to the evaluation of groundwater saturation. 7 refs., 5 figs., 3 tabs.

  18. Imaging continental shelf shallow stratigraphy by using different high-resolution seismic sources: an example from the Calabro-Tyrrhenian margin (Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    Eleonora Martorelli

    2010-01-01

    Full Text Available High-resolution seismic reflection profiles of the Calabro-Tyrrhenian continental shelf were collected using different seismic sources (Sub-Bottom Profiler, Uniboom, Sparker 0.5-1-4.5 kJ. Noticeable differences and results were obtained both from a geophysical and geological-interpretative point of view. The availability of different sources permitted the definition of the most suitable seismostratigraphic characterization in terms of resolution, penetration and acoustic facies. Very high resolution stratigraphy was defined through profiles produced by different seismic systems used in parallel. This permitted the application of sequence-stratigraphy concepts with the reconstruction of a thick postglacial depositional sequence, formed by a transgressive and a high-stand systems tract. The thickness distribution of postglacial deposits reveals that the main depocenter (55-65 m is located offshore of the Coastal Range, along a stretch of coast supplied by several small and seasonal streams ("fiumare" and characterized by the lack of a coastal plain. This suggests the greater efficiency of sediment supply and bypass in this area relatively to sectors located offshore of the main rivers. The transgressive systems tract, usually thin or nearly absent, is particularly well developed (up to 33 m and is composed of up to three parasequences with a retrogradational stacking pattern. The high-stand systems tract, up to 30 m thick, is made up of two parasequences and has a quite regular geometry and acoustic facies.Perfis de reflexão sísmica de alta resolução da plataforma continental tirreniana de Calabro foram obtidos utilizando-se recursos sísmicos diversos (Perfilador de Sub-superfície, Uniboom, Sparker 0.5-1-4.5 kJ. Diferenças evidentes foram encontradas sob o ponto de vista geofísico e geológico-interpretativo. A disponibilidade de diferentes fontes permitiu a definição de uma caracterização sismo-estratigráfica mais acurada em termos

  19. Research on Bell-Shaped Vibratory Angular Rate Gyro’s Character of Resonator

    Directory of Open Access Journals (Sweden)

    Hong Liu

    2013-04-01

    Full Text Available Bell-shaped vibratory angular rate gyro (abbreviated as BVG is a new type Coriolis vibratory gyro that was inspired by Chinese traditional clocks. The resonator fuses based on a variable thickness axisymmetric multicurved surface shell. Its characteristics can directly influence the performance of BVG. The BVG structure not only has capabilities of bearing high overload, high impact and, compared with the tuning fork, vibrating beam, shell and a comb structure, but also a higher frequency to overcome the influence of the disturbance of the exterior environment than the same sized hemispherical resonator gyroscope (HRG and the traditional cylinder vibratory gyroscope. It can be widely applied in high dynamic low precision angular rate measurement occasions. The main work is as follows: the issue mainly analyzes the structure and basic principle, and investigates the bell-shaped resonator’s mathematical model. The reasonable structural parameters are obtained from finite element analysis and an intelligent platform. Using the current solid vibration gyro theory analyzes the structural characteristics and principles of BVG. The bell-shaped resonator is simplified as a paraboloid of the revolution mechanical model, which has a fixed closed end and a free opened end. It obtains the natural frequency and vibration modes based on the theory of elasticity. The structural parameters are obtained from the orthogonal method by the research on the structural parameters of the resonator analysis. It obtains the modal analysis, stress analysis and impact analysis with the chosen parameters. Finally, using the turntable experiment verifies the gyro effect of the BVG.

  20. Seismic hazard estimation of northern Iran using smoothed seismicity

    Science.gov (United States)

    Khoshnevis, Naeem; Taborda, Ricardo; Azizzadeh-Roodpish, Shima; Cramer, Chris H.

    2017-07-01

    This article presents a seismic hazard assessment for northern Iran, where a smoothed seismicity approach has been used in combination with an updated seismic catalog and a ground motion prediction equation recently found to yield good fit with data. We evaluate the hazard over a geographical area including the seismic zones of Azerbaijan, the Alborz Mountain Range, and Kopeh-Dagh, as well as parts of other neighboring seismic zones that fall within our region of interest. In the chosen approach, seismic events are not assigned to specific faults but assumed to be potential seismogenic sources distributed within regular grid cells. After performing the corresponding magnitude conversions, we decluster both historical and instrumental seismicity catalogs to obtain earthquake rates based on the number of events within each cell, and smooth the results to account for the uncertainty in the spatial distribution of future earthquakes. Seismicity parameters are computed for each seismic zone separately, and for the entire region of interest as a single uniform seismotectonic region. In the analysis, we consider uncertainties in the ground motion prediction equation, the seismicity parameters, and combine the resulting models using a logic tree. The results are presented in terms of expected peak ground acceleration (PGA) maps and hazard curves at selected locations, considering exceedance probabilities of 2 and 10% in 50 years for rock site conditions. According to our results, the highest levels of hazard are observed west of the North Tabriz and east of the North Alborz faults, where expected PGA values are between about 0.5 and 1 g for 10 and 2% probability of exceedance in 50 years, respectively. We analyze our results in light of similar estimates available in the literature and offer our perspective on the differences observed. We find our results to be helpful in understanding seismic hazard for northern Iran, but recognize that additional efforts are necessary to

  1. Identification of the 3D Vibratory Motion of a Rigid Body by Accelerometer Measurements

    Directory of Open Access Journals (Sweden)

    Francesca Di Puccio

    2004-01-01

    Full Text Available The identification of the motion of a rigid body by means of linear accelerometers is a problem already investigated by many researchers, but still debated. The optimisation of the number and placement of accelerometers is also another important aspect of the problem. In this study, an experimental procedure is proposed and applied to identify the rigid-body vibratory motion of the steering wheel of a sporting car, by means of six linear accelerometers. Some numerical simulations for investigating possible errors are also presented.

  2. Cavitation Erosion Tests Performed by Indirect Vibratory Method on Stainless Steel Welded Samples with Hardened Surface

    Directory of Open Access Journals (Sweden)

    Marian-Dumitru Nedeloni

    2012-09-01

    Full Text Available The paper presents the results of cavitation erosion tests performed on two types of samples. The materials of the samples are frequently used for manufacturing and repairs of the hydro turbines components submitted to cavitation. The first sample was made by welding of an austenitic stainless steel on austenito-feritic base material. The second sample was made similarly with the first but with a martensitic base material. After the welding processes, on both samples was applied a hardening treatment by surface peening. The cavitation erosion tests were performed on vibratory equipment using the indirect method with stationary specimen. The results show a good cavitation erosion resistance on both samples.

  3. Optimization of process parameters during vibratory welding technique using Taguchi's analysis

    OpenAIRE

    Singh, Pravin Kumar; Patel, D.; Prasad,S.B.

    2016-01-01

    With an aim to improve the mechanical properties of a weld joint, a new concept of vibratory setup has been designed which is capable to stir the molten weld pool before it solidifies during shielded metal arc welding (SMAW) operation. Mechanical vibration having resonance frequency of 300 Hz and amplitude of 0.5 mm was transferred to the molten weld pool of 6 mm thick mild steel butt-welded joints during the welding operation. The experimental work was conducted at various ranges of frequenc...

  4. Identification of elasticity modulus by vibratory analysis (Application to a natural composite: Aleppo pine wood

    Directory of Open Access Journals (Sweden)

    DAOUI Abdelhakim

    2018-01-01

    Full Text Available In this paper, we present a method for the determination of the elasticity modulus in the vibratory domain of materials. This approach is based on research and interpretation of the spectrum of natural frequencies resulting from natural vibrations based on the theory of elastic beams. The tests consist of classical tests of longitudinal vibrations of natural composite beams (Aleppo pine wood, long enough to observe some natural frequencies. This identification method showed a good correlation between the theoretical and experimental values, notably the evaluation of the modal parameter for the case of the resonant frequencies and the identification of the modulus of elasticity of the materials used.

  5. Penile vibratory stimulation and electroejaculation in the treatment of ejaculatory dysfunction.

    Science.gov (United States)

    Sønksen, Jens; Ohl, Dana A

    2002-12-01

    The purpose of this review is to present the current understanding of penile vibratory stimulation (PVS) and electroejaculation (EEJ) procedures and its clinical use in men with ejaculatory dysfunction. Unfortunately, the record of treating such individuals has been quite poor, but within recent years development and refinement of PVS and EEJ in men with spinal cord injury (SCI) has significantly enhanced the prospects for treatment of ejaculatory dysfunction. The majority of spinal cord injured men are not able to produce antegrade ejaculation by masturbation or sexual stimulation. However, approximately 80% of all spinal cord injured men with an intact ejaculatory reflex arc (above T10) can obtain antegrade ejaculation with PVS. Electroejaculation may be successful in obtaining ejaculate from men with all types of SCI, including men who do not have major components of the ejaculatory reflex arc. Because vibratory stimulation is very simple in use, non-invasive, it does not require anaesthesia and is preferred by the patients when compared with EEJ, PVS is recommended to be the first choice of treatment in spinal cord injured men. Furthermore, EEJ has been successfully used to induce ejaculation in men with multiple sclerosis and diabetic neuropathy. Any other conditions which affect the ejaculatory mechanism of the central and/or peripheral nervous system including surgical nerve injury may be treated successfully with EEJ. Finally, for sperm retrieval and sperm cryopreservation before intensive anticancer therapy in pubertal boys, PVS and EEJ have been successfully performed in patients who failed to obtain ejaculation by masturbation. Nearly all data concerning semen characteristics in men with ejaculatory dysfuntion originate from spinal cord injured men. Semen analyses demonstrate low sperm motility rates in the majority of spinal cord injured men. The data give evidence of a decline in spermatogenesis and motility of ejaculated spermatozoa shortly after (few

  6. Comparison of energy costs for different control laws of a vibratory robot

    Science.gov (United States)

    Golitsyna, Maria

    2017-01-01

    In the study there are introduced several control methods that maximize average velocity of the vibratory robot subject to several constraints. The robot is presented by a rigid box with a pendulum inside it. It can move forwards and backwards and there is a Coulomb friction between the box and the surface. In the paper it is not only shown the difference and advantages of proposed control laws but there is also done a comparison between efforts done by the motor that provides rotation of the pendulum for different control methods.

  7. A transferable approach towards rapid inventory data capturing for seismic vulnerability assessment using open-source geospatial technologies

    Science.gov (United States)

    Wieland, M.; Pittore, M.; Parolai, S.; Zschau, J.

    2012-04-01

    Geospatial technologies are increasingly being used in pre-disaster vulnerability assessment and post-disaster impact assessment for different types of hazards. Especially the use of remote sensing data has been strongly promoted in recent years due to its capabilities of providing up-to-date information over large areas at a comparatively low cost with increasingly high spatial, temporal and spectral resolution. Despite its clear potentials, a purely remote sensing based approach has its limitations in that it is only capable of providing information about the birds-eye view of the objects of interest. The use of omnidirectional imaging in addition can provide the necessary street-view that furthermore allows for a rapid visual screening of a buildings façade. In this context, we propose an integrated approach to rapid inventory data capturing for the assessment of structural vulnerability of buildings in case of an earthquake. Globally available low-cost data sources are preferred and the tools are developed on an open-source basis to allow for a high degree of transferability and usability. On a neighbourhood scale medium spatial but high temporal and spectral resolution satellite images are analysed to outline areas of homogeneous urban structure. Following a proportional allocation scheme, for each urban structure type representative sample areas are selected for a more detailed analysis of the building stock with high resolution image data. On a building-by-building scale a ground-based, rapid visual survey is performed using an omnidirectional imaging system driven around with a car inside the identified sample areas. Processing of the acquired images allows for an extraction of vulnerability-related features of single buildings (e.g. building height, detection of soft-storeys). An analysis of high resolution satellite images provides with further inventory features (e.g. footprint area, shape irregularity). Since we are dealing with information coming from

  8. Seismic bearing

    Science.gov (United States)

    Power, Dennis

    2009-05-01

    Textron Systems (Textron) has been using geophones for target detection for many years. This sensing capability was utilized for detection and classification purposes only. Recently Textron has been evaluating multiaxis geophones to calculate bearings and track targets more specifically personnel. This capability will not only aid the system in locating personnel in bearing space or cartesian space but also enhance detection and reduce false alarms. Textron has been involved in the testing and evaluation of several sensors at multiple sites. One of the challenges of calculating seismic bearing is an adequate signal to noise ratio. The sensor signal to noise ratio is a function of sensor coupling to the ground, seismic propagation and range to target. The goals of testing at multiple sites are to gain a good understanding of the maximum and minimum ranges for bearing and detection and to exploit that information to tailor sensor system emplacement to achieve desired performance. Test sites include 10A Site Devens, MA, McKenna Airfield Ft. Benning, GA and Yuma Proving Ground Yuma, AZ. Geophone sensors evaluated include a 28 Hz triax spike, a 15 Hz triax spike and a hybrid triax spike consisting of a 10 Hz vertical geophone and two 28 Hz horizontal geophones. The algorithm uses raw seismic data to calculate the bearings. All evaluated sensors have triaxial geophone configuration mounted to a spike housing/fixture. The suite of sensors also compares various types of geophones to evaluate benefits in lower bandwidth. The data products of these tests include raw geophone signals, seismic features, seismic bearings, seismic detection and GPS position truth data. The analyses produce Probability of Detection vs range, bearing accuracy vs range, and seismic feature level vs range. These analysis products are compared across test sites and sensor types.

  9. Estimation of strong ground motion in broad-frequency band based on a seismic source scaling model and an empirical Green's function technique

    Directory of Open Access Journals (Sweden)

    K. Kamae

    1994-06-01

    Full Text Available We introduce a generalized method for simulating strong ground motion from large earthquakes by summing subevent records to follow the ?2 law. The original idea of the method is based on a constant stress parameter between the target event and the subevent. It is applicable to a case where both events have a different stress drop after some manipulation. However, the simulation for a very large earthquake from a small event with this method has inevitably some deficiencies of spectral amplitudes in the intermediate frequency range deviating f`rom the ?2 model, although the high and low frequency motions match the scaling. We improve the simulation algorithm so as not to make spectral sags, introducing self-similar distribution of subfaults with different sizes in the fault plane, so-called fractal composite faulting model. We show successful simulations for intermediate-sized earthquakes (MJMA = 5.0, 6.0 and 6.1, the large aftershocks of the 1983 Akita-Oki earthquake. using the records of smaller aftershocks (MJMA = 3.9 and 5.0 as an empirical Green's function. Further, we attempted to estimate strong ground motion for the 1946 Nankai earthquake with Mw 8.2, using the records of a MJMA 5.1 earthquake occurring near the source region of the mainshock. We found that strong ground motions simulated for the fractal composite faulting model with two asperities radiating significantly high frequency motions matched well the observed data such as the near-field displacement record, the source spectrum estimated from the teleseismic record, and the seismic intensity distribution during the 1946 Nankai earthquake.

  10. Late Mesozoic magmatic plumbing system in the onshore-offshore area of Hong Kong: Insight from 3-D active-source seismic tomography

    Science.gov (United States)

    Xia, Shaohong; Zhao, Dapeng

    2014-12-01

    We used active source wide-angle seismic data to determine a high-resolution P-wave crustal tomography beneath the onshore-offshore area of Hong Kong at the southern end of a broad belt dominated by the late Mesozoic intrusive and extrusive rocks in the coastal region of Southeast China. The active source data are much more precise than the natural earthquake data and so can be used to study the fine crustal structure. Our results reveal a localized high-velocity anomaly in the lower crust offshore between Hong Kong and Dangan Island, which may reflect basaltic underplating that is closely associated with formation of voluminous silicic eruptions and granitoid plutons in the onshore-offshore area of Hong Kong. Tilted high-velocity zones connecting with the localized high-velocity anomaly in the lower crust are clearly visible in the entire crust beneath Dangan Island and the calderas of Hong Kong. Taking into account the previous geochemical, petrologic and numerical modeling results, we think that the tilted high-velocity zones may be the results of mingling of mafic and felsic end members and extreme degree of crustal partial melt extraction necessary to generate a large amount of extrusive rocks in the calderas, reflecting cooled magma conduits as a manifestation of solidified Late Mesozoic magmatic plumbing system in the crust. Considering the petrologic and geochemical characteristics of the late Mesozoic granites and basalt in Southeast China, we suggest that subduction and dehydration of the paleo-Pacific plate might trigger the basaltic magma underplating and result in extensive crust-mantle interaction, which not only provided necessary heat energy to cause the crustal partial melting, but also added minor mafic materials to the newly generated granitic melts. This model explains our tomographic results as well as the intimate mingling of coeval mafic and silicic magmas in Hong Kong. Intersecting faults could play an important role in forming magma

  11. High Voltage Seismic Generator

    Science.gov (United States)

    Bogacz, Adrian; Pala, Damian; Knafel, Marcin

    2015-04-01

    This contribution describes the preliminary result of annual cooperation of three student research groups from AGH UST in Krakow, Poland. The aim of this cooperation was to develop and construct a high voltage seismic wave generator. Constructed device uses a high-energy electrical discharge to generate seismic wave in ground. This type of device can be applied in several different methods of seismic measurement, but because of its limited power it is mainly dedicated for engineering geophysics. The source operates on a basic physical principles. The energy is stored in capacitor bank, which is charged by two stage low to high voltage converter. Stored energy is then released in very short time through high voltage thyristor in spark gap. The whole appliance is powered from li-ion battery and controlled by ATmega microcontroller. It is possible to construct larger and more powerful device. In this contribution the structure of device with technical specifications is resented. As a part of the investigation the prototype was built and series of experiments conducted. System parameter was measured, on this basis specification of elements for the final device were chosen. First stage of the project was successful. It was possible to efficiently generate seismic waves with constructed device. Then the field test was conducted. Spark gap wasplaced in shallowborehole(0.5 m) filled with salt water. Geophones were placed on the ground in straight line. The comparison of signal registered with hammer source and sparker source was made. The results of the test measurements are presented and discussed. Analysis of the collected data shows that characteristic of generated seismic signal is very promising, thus confirms possibility of practical application of the new high voltage generator. The biggest advantage of presented device after signal characteristics is its size which is 0.5 x 0.25 x 0.2 m and weight approximately 7 kg. This features with small li-ion battery makes

  12. SELENA - An open-source tool for seismic risk and loss assessment using a logic tree computation procedure

    Science.gov (United States)

    Molina, S.; Lang, D. H.; Lindholm, C. D.

    2010-03-01

    The era of earthquake risk and loss estimation basically began with the seminal paper on hazard by Allin Cornell in 1968. Following the 1971 San Fernando earthquake, the first studies placed strong emphasis on the prediction of human losses (number of casualties and injured used to estimate the needs in terms of health care and shelters in the immediate aftermath of a strong event). In contrast to these early risk modeling efforts, later studies have focused on the disruption of the serviceability of roads, telecommunications and other important lifeline systems. In the 1990s, the National Institute of Building Sciences (NIBS) developed a tool (HAZUS ®99) for the Federal Emergency Management Agency (FEMA), where the goal was to incorporate the best quantitative methodology in earthquake loss estimates. Herein, the current version of the open-source risk and loss estimation software SELENA v4.1 is presented. While using the spectral displacement-based approach (capacity spectrum method), this fully self-contained tool analytically computes the degree of damage on specific building typologies as well as the associated economic losses and number of casualties. The earthquake ground shaking estimates for SELENA v4.1 can be calculated or provided in three different ways: deterministic, probabilistic or based on near-real-time data. The main distinguishing feature of SELENA compared to other risk estimation software tools is that it is implemented in a 'logic tree' computation scheme which accounts for uncertainties of any input (e.g., scenario earthquake parameters, ground-motion prediction equations, soil models) or inventory data (e.g., building typology, capacity curves and fragility functions). The data used in the analysis is assigned with a decimal weighting factor defining the weight of the respective branch of the logic tree. The weighting of the input parameters accounts for the epistemic and aleatoric uncertainties that will always follow the necessary

  13. Updated Colombian Seismic Hazard Map

    Science.gov (United States)

    Eraso, J.; Arcila, M.; Romero, J.; Dimate, C.; Bermúdez, M. L.; Alvarado, C.

    2013-05-01

    The Colombian seismic hazard map used by the National Building Code (NSR-98) in effect until 2009 was developed in 1996. Since then, the National Seismological Network of Colombia has improved in both coverage and technology providing fifteen years of additional seismic records. These improvements have allowed a better understanding of the regional geology and tectonics which in addition to the seismic activity in Colombia with destructive effects has motivated the interest and the need to develop a new seismic hazard assessment in this country. Taking advantage of new instrumental information sources such as new broad band stations of the National Seismological Network, new historical seismicity data, standardized global databases availability, and in general, of advances in models and techniques, a new Colombian seismic hazard map was developed. A PSHA model was applied. The use of the PSHA model is because it incorporates the effects of all seismic sources that may affect a particular site solving the uncertainties caused by the parameters and assumptions defined in this kind of studies. First, the seismic sources geometry and a complete and homogeneous seismic catalog were defined; the parameters of seismic rate of each one of the seismic sources occurrence were calculated establishing a national seismotectonic model. Several of attenuation-distance relationships were selected depending on the type of seismicity considered. The seismic hazard was estimated using the CRISIS2007 software created by the Engineering Institute of the Universidad Nacional Autónoma de México -UNAM (National Autonomous University of Mexico). A uniformly spaced grid each 0.1° was used to calculate the peak ground acceleration (PGA) and response spectral values at 0.1, 0.2, 0.3, 0.5, 0.75, 1, 1.5, 2, 2.5 and 3.0 seconds with return periods of 75, 225, 475, 975 and 2475 years. For each site, a uniform hazard spectrum and exceedance rate curves were calculated. With the results, it is

  14. Structural-Acoustic Coupling Effects on the Non-Vacuum Packaging Vibratory Cylinder Gyroscope

    Science.gov (United States)

    Xi, Xiang; Wu, Xuezhong; Wu, Yulie; Zhang, Yongmeng; Tao, Yi; Zheng, Yu; Xiao, Dingbang

    2013-01-01

    The resonant shells of vibratory cylinder gyroscopes are commonly packaged in metallic caps. In order to lower the production cost, a portion of vibratory cylinder gyroscopes do not employ vacuum packaging. However, under non-vacuum packaging conditions there can be internal acoustic noise leading to considerable acoustic pressure which is exerted on the resonant shell. Based on the theory of the structural-acoustic coupling, the dynamical behavior of the resonant shell under acoustic pressure is presented in this paper. A finite element (FE) model is introduced to quantitatively analyze the effect of the structural-acoustic coupling. Several main factors, such as sealing cap sizes and degree of vacuum which directly affect the vibration of the resonant shell, are studied. The results indicate that the vibration amplitude and the operating frequency of the resonant shell will be changed when the effect of structural-acoustic coupling is taken into account. In addition, an experiment was set up to study the effect of structural-acoustic coupling on the sensitivity of the gyroscope. A 32.4 mV/°/s increase of the scale factor and a 6.2 Hz variation of the operating frequency were observed when the radial gap size between the resonant shell and the sealing cap was changed from 0.5 mm to 20 mm. PMID:24351631

  15. Optimization of process parameters during vibratory welding technique using Taguchi's analysis

    Directory of Open Access Journals (Sweden)

    Pravin Kumar Singh

    2016-09-01

    Full Text Available With an aim to improve the mechanical properties of a weld joint, a new concept of vibratory setup has been designed which is capable to stir the molten weld pool before it solidifies during shielded metal arc welding (SMAW operation. Mechanical vibration having resonance frequency of 300 Hz and amplitude of 0.5 mm was transferred to the molten weld pool of 6 mm thick mild steel butt-welded joints during the welding operation. The experimental work was conducted at various ranges of frequencies, welding current and welding speed. Taguchi's analysis technique has been applied to optimize the process parameters; the response values for analysis are yield strength and micro-hardness. The test results showed that with the application of the vibratory treatment the values of hardness and tensile properties increased. The auxiliary vibrations induced into the weld pool resulted in increased micro-hardness of the weld metal which indicates the orientation of the crystal and refinement of grains took place. This study shows that vibration applied into the weld pool can be successfully improved the mechanical properties of welded joints. Thus this research attempt provided an alternative welding technique for grain refinement of weldments.

  16. Mechanical and Electrical Noise in Sense Channel of MEMS Vibratory Gyroscopes.

    Science.gov (United States)

    Ding, Xukai; Jia, Jia; Gao, Yang; Li, Hongsheng

    2017-10-11

    This paper presents a theoretical analysis of mechanical and electrical noise in the sense channel of micro-electromechanical systems (MEMS) vibratory gyroscopes. Closed-form expressions for the power spectral density (PSD) of the noise equivalent rate (NER) of gyroscopes in the open-loop and the force-rebalance operations are derived by using an averaged PSD model and an equivalent transfer function. The obtained expressions are verified through numerical simulations, demonstrating close agreements between the analytic and the numerical models. Based on the derived expressions for the PSD of the NER, the impacts of the modal frequency split, quality factor, and the gain of the feedback forcer, as well as the gain of the signal conditioning circuit, on the gyroscope noise characteristics are theoretically analyzed. In addition, the angle random walk (ARW) and the standard deviation of the NER are also discussed through the PSD models. Finally, the effects of the loop closing, the mode matching, and the gain of the feedback forcer on the PSD of the NER were verified via a MEMS vibratory gyroscope with a tunable modal frequency split.

  17. [Penile vibratory stimulation and electroejaculation in the treatment of ejaculatory dysfunction].

    Science.gov (United States)

    Fan, Long-chang; Liu, Ji-hong

    2005-03-01

    The fertility potential of infertile men can be enhanced to a great extent by the application of assisted reproduction techniques such as intrauterine insemination or in-vitro fertilization with or without intracytoplasmic sperm injection, but how to obtain semen from men with ejaculatory dysfunction remains a problem. The development and refinement of penile vibratory stimulation (PVS) and electroejaculation (EEJ) have significantly brightened the prospects for the treatment of ejaculatory dysfunction. Because vibratory stimulation is non-invasive and easy to perform, and needs no anaesthesia, it is preferred by most of the patients to EEJ, and recommended to be the first choice of treatment for ejaculatory dysfunction. Approximately 80% of all ejaculatory dysfunction men with an intact ejaculatory reflex arc (above T10 ) can obtain antegrade ejaculation by PVS. Any condition which affects the ejaculatory mechanism of the central and/or peripheral nervous system including surgical nerve injury may be treated successfully by EEJ. The purpose of this review is to present the current understanding of PVS and EEJ procedures and their clinical use in men with ejaculatory dysfunction.

  18. Constraining earthquake source inversions with GPS data: 2. A two-step approach to combine seismic and geodetic data sets

    Science.gov (United States)

    Custodio, S.; Page, M.T.; Archuleta, R.J.

    2009-01-01

    We present a new method to combine static and wavefield data to image earthquake ruptures. Our combined inversion is a two-step procedure, following the work of Hernandez et al. (1999), and takes into account the differences between the resolutions of the two data sets. The first step consists of an inversion of the static field, which yields a map of slip amplitude. This inversion exploits a special irregular grid that takes into account the resolution of the static data. The second step is an inversion of the radiated wavefield; it results in the determination of the time evolution of slip on the fault. In the second step, the slip amplitude is constrained to resemble the static slip amplitude map inferred from the GPS inversion. Using this combined inversion, we study the source process of the 2004 M6 Parkfield, California, earthquake. We conclude that slip occurred in two main regions of the fault, each of which displayed distinct rupture behaviors. Slip initiated at the hypocenter with a very strong bilateral burst of energy. Here, slip was localized in a narrow area approximately 10 km long, the rupture velocity was very fast (???3.5 km/s), and slip only lasted a short period of time (<1 s). Then the rupture proceeded to a wider region 12-20 km northwest of the hypocenter. Here, the earthquake developed in a more moderated way: the rupture velocity slowed to ???3.0 km/s and slip lasted longer (1-2 s). The maximum slip amplitude was 0.45 m. Copyright 2009 by the American Geophysical Union.

  19. Seismic Studies

    Energy Technology Data Exchange (ETDEWEB)

    R. Quittmeyer

    2006-09-25

    This technical work plan (TWP) describes the efforts to develop and confirm seismic ground motion inputs used for preclosure design and probabilistic safety 'analyses and to assess the postclosure performance of a repository at Yucca Mountain, Nevada. As part of the effort to develop seismic inputs, the TWP covers testing and analyses that provide the technical basis for inputs to the seismic ground-motion site-response model. The TWP also addresses preparation of a seismic methodology report for submission to the U.S. Nuclear Regulatory Commission (NRC). The activities discussed in this TWP are planned for fiscal years (FY) 2006 through 2008. Some of the work enhances the technical basis for previously developed seismic inputs and reduces uncertainties and conservatism used in previous analyses and modeling. These activities support the defense of a license application. Other activities provide new results that will support development of the preclosure, safety case; these results directly support and will be included in the license application. Table 1 indicates which activities support the license application and which support licensing defense. The activities are listed in Section 1.2; the methods and approaches used to implement them are discussed in more detail in Section 2.2. Technical and performance objectives of this work scope are: (1) For annual ground motion exceedance probabilities appropriate for preclosure design analyses, provide site-specific seismic design acceleration response spectra for a range of damping values; strain-compatible soil properties; peak motions, strains, and curvatures as a function of depth; and time histories (acceleration, velocity, and displacement). Provide seismic design inputs for the waste emplacement level and for surface sites. Results should be consistent with the probabilistic seismic hazard analysis (PSHA) for Yucca Mountain and reflect, as appropriate, available knowledge on the limits to extreme ground

  20. Seismic reflection and refraction methods

    Digital Repository Service at National Institute of Oceanography (India)

    Chaubey, A.K.

    , reflection method is a very sophisticated version of the echosounding used in submarines, ships, and radar systems. Whereas, in seismic refraction method, principal portion of the wave-path is along the interface between the two layers and hence... into electrical signals, which are recorded digitally. The Ocean Bottom Seismometers 221 (OBS) are normally designed to record the earth motion under oceans and lakes from air-gun seismic sources. The air gun array is towed behind a ship usually at a...

  1. Passive Seismic Imaging

    Science.gov (United States)

    Artman, B. W.

    2003-12-01

    Traditionally, passive seismology connotes the use of earthquake signals from continuously recording receivers. Small time windows around the arrivals of earthquakes are then analyzed in myriad fashion. I will distinguish from this body of work, the notion of passive seismic imaging, which requires no knowledge of the time or characteristics of a source event. Instead, by using the ambient noise in the subsurface with all orders of scattering and thus randomized directionality, passive seismic imaging can produce results analogous to conventional controlled source experiments. Mathematical proof of the concept of passive seismic imaging has been presented in the literature from several foundations. The results reduce to the simple concept of cross-correlating many long recordings within a simultaneously deployed array. This generates panels with the kinematics of a shot-gather from a standard reflection seismic acquisition effort. Results from synthetic data sets show the validity of the method for point diffractor, and layered earth models. Noting the similarity of form of the standard approach to produce shot-gathers with the imaging condition of shot-profile migration, I then show that migrating the raw passive seismic data without the correlation step produces the the correct image. The synthetic data from above is used to demonstrate the technique. By comparison, this image is of better quality, and demands less compute time, than migrating the data having been cross-correlated first. Finally, both techniques are used to process a 2x2 meter, 72-channel array recorded on the beach sand of Monterey Bay, California. Approximately one meter below the sand, a six inch diameter plastic pipe was buried to serve as a target.

  2. dispel4py : An Open Source Python Framework for Encoding, Mapping and Reusing Seismic Continuous Data Streams: Intensive Analysis and Data Mining.

    Science.gov (United States)

    Filgueira, R.; Krause, A.; Atkinson, M.; Spinuso, A.; Klampanos, I.; Magnoni, F.; Casarotti, E.; Vilotte, J. P.

    2015-12-01

    Scientific workflows are needed by many scientific communities, such as seismology, as they enable easy composition and execution of applications, enabling scientists to focus on their research without being distracted by arranging computation and data management. However, there are challenges to be addressed. In many systems users have to adapt their codes and data movement as they change from one HPC-architecture to another. They still need to be aware of the computing architectures available for achieving the best application performance. We present dispel4py, an open-source framework presented as a Python library for encoding and automating data-intensive scientific methods as a graph of operations coupled together by data-streams. It enables scientists to develop and experiment with their own data-intensive applications using their familiar work environment. These are then automatically mapped to a variety of HPC-architectures, i.e., MPI, multiprocessing, Storm and Spark frameworks, increasing the chances to reuse their applications in different computing resources. dispel4py comes with data provenance, as shown in the screenshot, and with an information registry that can be accessed transparently from within workflows. dispel4py has been enhanced with a new run-time adaptive compression strategy to reduce the data stream volume and a diagnostic tool which monitors workflow performance and computes the most efficient parallelisation to use. dispel4py has been used by seismologists in the project VERCE for seismic ambient noise cross-correlation applications and for orchestrated HPC wave simulation and data misfit analysis workflows; two data-intensive problems that are common in today's research practice. Both have been tested in several local computing resources and later submitted to a variety of European PRACE HPC-architectures (e.g. SuperMUC & CINECA) for longer runs without change. Results show that dispel4py is an easy tool for developing, sharing and

  3. Comparisons between vs30 and spectral response for 30 sites in Newcastle, Australia from collocated seismic cone penetrometer, active- and passive-source vs data

    Science.gov (United States)

    Volti, Theodora; Burbidge, David; Collins, Clive; Asten, Michael; Odum, Jackson K.; Stephenson, William J.; Pascal, Chris; Holzschuh, Josef

    2016-01-01

    Although the time‐averaged shear‐wave velocity down to 30 m depth (VS30) can be a proxy for estimating earthquake ground‐motion amplification, significant controversy exists about its limitations when used as a single parameter for the prediction of amplification. To examine this question in absence of relevant strong‐motion records, we use a range of different methods to measure the shear‐wave velocity profiles and the resulting theoretical site amplification factors (AFs) for 30 sites in the Newcastle area, Australia, in a series of blind comparison studies. The multimethod approach used here combines past seismic cone penetrometer and spectral analysis of surface‐wave data, with newly acquired horizontal‐to‐vertical spectral ratio, passive‐source surface‐wave spatial autocorrelation (SPAC), refraction microtremor (ReMi), and multichannel analysis of surface‐wave data. The various measurement techniques predicted a range of different AFs. The SPAC and ReMi techniques have the smallest overall deviation from the median AF for the majority of sites. We show that VS30 can be related to spectral response above a period T of 0.5 s but not necessarily with the maximum amplification according to the modeling done based on the measured shear‐wave velocity profiles. Both VS30 and AF values are influenced by the velocity ratio between bedrock and overlying sediments and the presence of surficial thin low‐velocity layers (site. AF maxima are the highest in the hard classes, which is the inverse of the findings used in the Australian Building Code. Only for T>0.5  s do the amplification curves consistently show higher values for soft site classes and lower for hard classes.

  4. Seismic Symphonies

    Science.gov (United States)

    Strinna, Elisa; Ferrari, Graziano

    2015-04-01

    The project started in 2008 as a sound installation, a collaboration between an artist, a barrel organ builder and a seismologist. The work differs from other attempts of sound transposition of seismic records. In this case seismic frequencies are not converted automatically into the "sound of the earthquake." However, it has been studied a musical translation system that, based on the organ tonal scale, generates a totally unexpected sequence of sounds which is intended to evoke the emotions aroused by the earthquake. The symphonies proposed in the project have somewhat peculiar origins: they in fact come to life from the translation of graphic tracks into a sound track. The graphic tracks in question are made up by copies of seismograms recorded during some earthquakes that have taken place around the world. Seismograms are translated into music by a sculpture-instrument, half a seismograph and half a barrel organ. The organ plays through holes practiced on paper. Adapting the documents to the instrument score, holes have been drilled on the waves' peaks. The organ covers about three tonal scales, starting from heavy and deep sounds it reaches up to high and jarring notes. The translation of the seismic records is based on a criterion that does match the highest sounds to larger amplitudes with lower ones to minors. Translating the seismogram in the organ score, the larger the amplitude of recorded waves, the more the seismogram covers the full tonal scale played by the barrel organ and the notes arouse an intense emotional response in the listener. Elisa Strinna's Seismic Symphonies installation becomes an unprecedented tool for emotional involvement, through which can be revived the memory of the greatest disasters of over a century of seismic history of the Earth. A bridge between art and science. Seismic Symphonies is also a symbolic inversion: the instrument of the organ is most commonly used in churches, and its sounds are derived from the heavens and

  5. Modal Damping Ratio and Optimal Elastic Moduli of Human Body Segments for Anthropometric Vibratory Model of Standing Subjects.

    Science.gov (United States)

    Gupta, Manoj; Gupta, T C

    2017-10-01

    The present study aims to accurately estimate inertial, physical, and dynamic parameters of human body vibratory model consistent with physical structure of the human body that also replicates its dynamic response. A 13 degree-of-freedom (DOF) lumped parameter model for standing person subjected to support excitation is established. Model parameters are determined from anthropometric measurements, uniform mass density, elastic modulus of individual body segments, and modal damping ratios. Elastic moduli of ellipsoidal body segments are initially estimated by comparing stiffness of spring elements, calculated from a detailed scheme, and values available in literature for same. These values are further optimized by minimizing difference between theoretically calculated platform-to-head transmissibility ratio (TR) and experimental measurements. Modal damping ratios are estimated from experimental transmissibility response using two dominant peaks in the frequency range of 0-25 Hz. From comparison between dynamic response determined form modal analysis and experimental results, a set of elastic moduli for different segments of human body and a novel scheme to determine modal damping ratios from TR plots, are established. Acceptable match between transmissibility values calculated from the vibratory model and experimental measurements for 50th percentile U.S. male, except at very low frequencies, establishes the human body model developed. Also, reasonable agreement obtained between theoretical response curve and experimental response envelop for average Indian male, affirms the technique used for constructing vibratory model of a standing person. Present work attempts to develop effective technique for constructing subject specific damped vibratory model based on its physical measurements.

  6. Post-seismic relaxation from geodetic and seismic data

    Directory of Open Access Journals (Sweden)

    Mikhail V. Rodkin

    2017-01-01

    Full Text Available We have examined the aftershock sequence and the post-seismic deformation process of the Parkfield earthquake (2004, M = 6, California, USA source area using GPS data. This event was chosen because of the possibility of joint analysis of data from the rather dense local GPS network (from SOPAC Internet archive and of the availability of the rather detailed aftershock sequence data (http://www.ncedc.org/ncedc/catalog-search.html. The relaxation process of post-seismic deformation prolongs about the same 400 days as the seismic aftershock process does. Thus, the aftershock process and the relaxation process in deformation could be the different sides of the same process. It should be noted that the ratio of the released seismic energy and of the GPS obtained deformation is quite different for the main shock and for the aftershock stage. The ratio of the released seismic energy to the deformation value decreases essentially for the post-shock process. The similar change in the seismic energy/deformation value ratio is valid in a few other strong earthquakes. Thus, this decrease seems typical of aftershock sequences testifying for decrease of ratio of elastic to inelastic deformation in the process of post-shock relaxation when the source area appears to be mostly fractured after the main shock occurs, but the healing process had no yet sufficient time to develop.

  7. seismic-py: Reading seismic data with Python

    Directory of Open Access Journals (Sweden)

    2008-08-01

    Full Text Available The field of seismic exploration of the Earth has changed
    dramatically over the last half a century. The Society of Exploration
    Geophysicists (SEG has worked to create standards to store the vast
    amounts of seismic data in a way that will be portable across computer
    architectures. However, it has been impossible to predict the needs of the
    immense range of seismic data acquisition systems. As a result, vendors have
    had to bend the rules to accommodate the needs of new instruments and
    experiment types. For low level access to seismic data, there is need for a
    standard open source library to allow access to a wide range of vendor data
    files that can handle all of the variations. A new seismic software package,
    seismic-py, provides an infrastructure for creating and managing drivers for
    each particular format. Drivers can be derived from one of the known formats
    and altered to handle any slight variations. Alternatively drivers can be
    developed from scratch for formats that are very different from any previously
    defined format. Python has been the key to making driver development easy
    and efficient to implement. The goal of seismic-py is to be the base system
    that will power a wide range of experimentation with seismic data and at the
    same time provide clear documentation for the historical record of seismic
    data formats.

  8. Effect of residual stress on modal patterns of MEMS vibratory gyroscope

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Shankar, E-mail: shankardutta77@gmail.com; Panchal, Abha; Kumar, Manoj; Pal, Ramjay; Bhan, R. K. [Solid State Physics Laboratory, DRDO, Lucknow Road, Timarpur, Delhi, India 110054 (India)

    2016-04-13

    Deep boron diffusion often induces residual stress in bulk micromachined MEMS structures, which may affect the MEMS devices operation. In this study, we studied the modal patterns of MEMS vibratory gyroscope under the residual stress (100 – 1000 MPa). Modal patterns and modal frequencies of the gyro are found to be dependent on the residual stress values. Without any residual stress, the modal frequencies drive and sense modeswere found to be 20.06 kHz and 20.36 kHz respectively. In presence of 450 MPa residual stress, the modal frequencies of the drive and sense modes were changed to 42.75 kHz and 43.07 kHz respectively.

  9. Characterization of vibratory turning in cutting zone using a pneumatic quick-stop device

    Directory of Open Access Journals (Sweden)

    Saeid Amini

    2017-04-01

    Full Text Available Shear angle and sticking length are two crucial parameters in mechanics of metal cutting. These two parameters directly influence machinability factors such as cutting forces. Thus, shear angle and sticking length were investigated in vibratory turning process by using a pneumatic quick-stop device which was designed and fabricated, in this study. After preparation of ultrasonic assisted turning set-up, experimental tests have been carried out on two types of steel: AISI-1060 and AISI 304. Accordingly, the process of chip formation in each particular cutting test was quickly stopped when deformed chip was still in contact with workpiece. As a result, it was revealed that added linear vibration leads the turning operation to be improved by increase of shear angle and decrease of sticking length. Moreover, the effect of ultrasonic vibration on cutting force and chip micro-hardness is evaluated.

  10. Interspectral combination type resonances of nonlinear conservative/nonconservative distributed parameter vibratory systems

    Science.gov (United States)

    Padovan, J.

    1985-06-01

    This paper investigates the properties/formation of combination type resonances of nonlinear conservative/nonconservative distributed parameter vibratory systems subject to external harmonic inputs containing a profusion of frequencies. Overall, this includes the evaluation of simultaneously excited harmonic, sub/superharmonics as well as combination harmonics created by interactions between external and interspectral system frequency branches. Additionally, effort is also given to handling nonconservative characteristics wherein critical damping levels may suppress specific combination harmonics. The foregoing is made possible through the development of a warped and constrained multiple time scales perturbation solution scheme. To illustrate the scheme as well as the nature and form of external and interspectral interaction, a nonlinear nonconservative version of the wave equation which is excited by complex external harmonic fields is given detailed consideration.

  11. Development of vibratory stress relief actuators based on giant magnetostrictive materials

    Science.gov (United States)

    He, Wen

    2005-12-01

    A kind of actuator, which is used in the high frequency Vibratory Stress Relief (VSR), was researched. The actuator is based on the technology of giant magnetostrictive materials. The design principle of the actuator was firstly analyzed, which consists of the analysis of giant magnetostrictive materials and a force generator. Then the design criterion of magnetostrictive actuators was deeply discussed, which includes the dimension design of magnetostrictive materials, the design of magnetic field and the design of elimination of heat. Finally, a real actuator was developed, which has been used in the high frequency VSR. The experimental results show that the developed actuator works very well. Large exciting force but small vibration amplitude will make it widely used in the VSR.

  12. Application of vibratory-percussion crusher for disintegration of supertough materials

    Science.gov (United States)

    Shishkin, E. V.; Kazakov, S. V.

    2017-10-01

    This article describes the results of theoretical and experimental studies of a vibratory-percussion crusher, which is driven from a pair of self-synchronizing vibration exciters, attached to the shell symmetrically about its vertical axis. In addition to that, crusher’s dynamic model is symmetrical and balanced. Forced oscillation laws for crusher working members and their amplitude-frequency characteristics have been inducted. Domains of existence of synchronous opposite-phase oscillations of crusher working members (crusher’s operating mode) and crusher capabilities have been identified. The results of mechanical and technological tests of a pilot crusher presented in the article show that this crusher may be viewed as an advanced machine for disintegration of supertough materials with minimum regrinding of finished products.

  13. Vibratory synchronization transmission of a cylindrical roller in a vibrating mechanical system excited by two exciters

    Science.gov (United States)

    Zhang, Xueliang; Wen, Bangchun; Zhao, Chunyu

    2017-11-01

    In present work vibratory synchronization transmission (VST) of a cylindrical roller with dry friction in a vibrating mechanical system excited by two exciters, is studied. Using the average method, the criterion of implementing synchronization of two exciters and that of ensuring VST of a roller, are achieved. The criterion of stability of the synchronous states satisfies the Routh-Hurwitz principle. The influences of the structural parameters of the system to synchronization and stability, are discussed numerically, which can be served as the theoretical foundation for engineering designs. An experiment is carried out, which approximately verify the validity of the theoretical and numerical results, as well as the feasibility of the method used. Utilizing the VST theory of a roller, some types of vibrating crushing or grinding equipments, etc., can be designed.

  14. A novel oscillation control for MEMS vibratory gyroscopes using a modified electromechanical amplitude modulation technique

    Science.gov (United States)

    Ma, Wei; Lin, Yiyu; Liu, Siqi; Zheng, Xudong; Jin, Zhonghe

    2017-02-01

    This paper reports a novel oscillation control algorithm for MEMS vibratory gyroscopes using a modified electromechanical amplitude modulation (MEAM) technique, which enhances the robustness against the frequency variation of the driving mode, compared to the conventional EAM (CEAM) scheme. In this approach, the carrier voltage exerted on the proof mass is frequency-modulated by the drive resonant frequency. Accordingly, the pick-up signal from the interface circuit involves a constant-frequency component that contains the amplitude and phase information of the vibration displacement. In other words, this informational detection signal is independent of the mechanical resonant frequency, which varies due to different batches, imprecise micro-fabrication and changing environmental temperature. In this paper, the automatic gain control loop together with the phase-locked loop are simultaneously analyzed using the averaging method and Routh-Hurwitz criterion, deriving the stability condition and the parameter optimization rules of the transient response. Then, a simulation model based on the real system is set up to evaluate the control algorithm. Further, the proposed MEAM method is tested using a field-programmable-gate-array based digital platform on a capacitive vibratory gyroscope. By optimizing the control parameters, the transient response of the drive amplitude reveals a settling time of 45.2 ms without overshoot, according well with the theoretical prediction and simulation results. The first measurement results show that the amplitude variance of the drive displacement is 12 ppm in an hour while the phase standard deviation is as low as 0.0004°. The mode-split gyroscope operating under atmospheric pressure demonstrates an outstanding performance. By virtue of the proposed MEAM method, the bias instability and angle random walk are measured to be 0.9° h-1 (improved by 2.4 times compared to the CEAM method) and 0.068° (√h)-1 (improved by 1.4 times

  15. Seismic scanning tunneling macroscope - Theory

    KAUST Repository

    Schuster, Gerard T.

    2012-09-01

    We propose a seismic scanning tunneling macroscope (SSTM) that can detect the presence of sub-wavelength scatterers in the near-field of either the source or the receivers. Analytic formulas for the time reverse mirror (TRM) profile associated with a single scatterer model show that the spatial resolution limit to be, unlike the Abbe limit of λ/2, independent of wavelength and linearly proportional to the source-scatterer separation as long as the point scatterer is in the near-field region; if the sub-wavelength scatterer is a spherical impedance discontinuity then the resolution will also be limited by the radius of the sphere. Therefore, superresolution imaging can be achieved as the scatterer approaches the source. This is analogous to an optical scanning tunneling microscope that has sub-wavelength resolution. Scaled to seismic frequencies, it is theoretically possible to extract 100 Hz information from 20 Hz data by imaging of near-field seismic energy.

  16. Probabilistic Seismic Hazard Analysis for Yemen

    Directory of Open Access Journals (Sweden)

    Rakesh Mohindra

    2012-01-01

    Full Text Available A stochastic-event probabilistic seismic hazard model, which can be used further for estimates of seismic loss and seismic risk analysis, has been developed for the territory of Yemen. An updated composite earthquake catalogue has been compiled using the databases from two basic sources and several research publications. The spatial distribution of earthquakes from the catalogue was used to define and characterize the regional earthquake source zones for Yemen. To capture all possible scenarios in the seismic hazard model, a stochastic event set has been created consisting of 15,986 events generated from 1,583 fault segments in the delineated seismic source zones. Distribution of horizontal peak ground acceleration (PGA was calculated for all stochastic events considering epistemic uncertainty in ground-motion modeling using three suitable ground motion-prediction relationships, which were applied with equal weight. The probabilistic seismic hazard maps were created showing PGA and MSK seismic intensity at 10% and 50% probability of exceedance in 50 years, considering local soil site conditions. The resulting PGA for 10% probability of exceedance in 50 years (return period 475 years ranges from 0.2 g to 0.3 g in western Yemen and generally is less than 0.05 g across central and eastern Yemen. The largest contributors to Yemen’s seismic hazard are the events from the West Arabian Shield seismic zone.

  17. An integrated analysis of source parameters, seismogenic structure, and seismic hazards related to the 2014 MS 6.3 Kangding earthquake, China

    Science.gov (United States)

    Xie, Zujun; Zheng, Yong; Liu, Chengli; Shan, Bin; Riaz, Muhammad Shahid; Xiong, Xiong

    2017-08-01

    On 22 November, 2014, an MS 6.3 earthquake occurred in Kangding County, China. Focal mechanism solution shows that the two nodal planes were 235°/82°/- 173° and 144°/83°/- 8° and the focal depth was 9 km. Seismic slip of the Kangding earthquake was bilateral with about 0.5 m maximum slip. The rupture zone was confined to depths ranging from 5 to 15 km and laterally extended along the slip and strike directions by about 10 and 12 km, respectively. Most of the seismic moment was released in the first 5 s of the rupture, resulting in an earthquake magnitude of MW 6.01. In contrast, a slip model obtained by interferometric synthetic aperture radar (InSAR) data indicates that the rupture zone was longer than that determined from the seismic data and the earthquake magnitude should be about MW 6.2. Although accounting for the contribution of the MS 5.8 aftershock and the other small aftershocks that occurred during the InSAR observations period, the total moment estimated based on the seismic slip model was significantly smaller than that obtained from the InSAR data. Based on our analysis, we found that the inconsistency between the results determined from the seismic data and the InSAR data may be caused by the decrease in the shear modulus at shallow depths, the noise in the InSAR data, and the occurrence of some afterslips in the northwest region of the fault zone. The seismic slip of this earthquake was too small to release the accumulated energy within the entire Xianshuihe fault. We also found that the Coulomb stress in the northwest zone of the Kangding-Daofu seismic gap increased as a result of the historical, 2008 MS 8.0 Wenchuan and the 2014 MS 6.3 Kangding earthquakes, suggesting that this area is expected to be a high seismic hazard region for the future.

  18. Introduction to seismic sources and source paramet

    OpenAIRE

    P. Bormann; Helmut Grosser

    1999-01-01

    Additional keywords: geological fault, fractal geologic systems, rupture kinematics and dynamics, induzierte seismische Ereignisse, Herdparameter, makroseismische Intensitaet, Magnitude, seismische Energie, seismisches Herdspektrum, seismisches Moment, Groesse des Herdgebietes, Herdflaechenloesungen, geologische Verwerfungen, fraktale geologische Systeme, Bruchkinematik und Dynamik

  19. Regional Seismic Intensity Anomalies in the Korean Peninsula and Its Implications for Seismic-Hazard Potentials

    Science.gov (United States)

    Park, Seongjun; Hong, Tae-Kyung

    2017-07-01

    The strength of seismic ground motion is a consequence of seismic source strength and medium response. The dependence of seismic amplitudes and seismic intensity on regional geological structures and crustal properties in the stable intraplate region around the Korean Peninsula is investigated. An instrumental seismic intensity scale based on spectral accelerations are proposed after calibrating with the reported macroseismic intensities. A representative seismic intensity attenuation curve for the Korean Peninsula is given by I(M_{ {L}},l,h) = -0.998 (± 0.222) + 1.72 (± 0.04) M_{ {L}} - 0.322 (± 0.027) {ln}(l^2 + h^2) - 0.00608 (± 0.00049) √{l^2 + h^2}, where I(M_{ {L}},l,h) is the seismic intensity at an epicentral distance l in km for an earthquake with local magnitude M_{ {L}} and focal depth h in km. Seismic intensities decay slowly with distance in the Korean Peninsula. The observed decay rate for the Korean Peninsula is comparable with those for other stable intraplate regions, while are lower than those for active regions. The regional seismic intensity anomalies present a characteristic correlation with geological structures. Positive seismic intensity anomalies appear in the Yeongnam massif, Okcheon belt and Gyeongsang basin, while negative seismic intensity anomalies in the Gyeonggi massif. The regional seismic intensity anomalies display positive correlations with crustal thicknesses, crustal amplifications, and seismicity density and negative correlations with heat flows. Positive seismic intensity anomalies are observed in the Yeongnam massif and Gyeongsang basin, suggesting high seismic-hazard potentials in the regions. The regional crustal properties may provide useful information on potential seismic hazards.

  20. Microseismic monitoring and analysis of induced seismicity source mechanisms in a retreating room and pillar coal mine in the Eastern United States

    Directory of Open Access Journals (Sweden)

    Morgen R. Leake

    2017-06-01

    Full Text Available A microseismic monitoring system was installed in an underground room and pillar coal mine in the Eastern United States to analyze the occurrence and characteristics of induced seismicity during the retreat of two panels in the mine. This study is the first microseismic monitoring effort at an underground coal mine in nearly 30 years. During the retreat of the first panel, an array of eight uniaxial geophones, installed 10 ft. into the roof, recorded events and their magnitudes. The second panel was monitored using an array of twelve uniaxial geophones and two triaxial geophones, also installed 10 ft. into the roof. Comparing the results of these studies, it has been found that the magnitude of seismic events is minimally affected by immediate roof geology or depth of cover. However, it was observed in both studies that the rate at which seismic events occurred did vary with changing roof geology and depth of cover. Using the seismic data from the second panel retreat, focal mechanism solutions were generated for 50 hand-picked events in order to determine if the failure was in compression, tension, or shear. Results of the focal mechanism solutions show that stress relief resulting in dilational events occurs at significant depths, 150–200 m in this case, beneath the active mining face.

  1. Final Report: Seismic Hazard Assessment at the PGDP

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhinmeng [KY Geological Survey, Univ of KY

    2007-06-01

    Selecting a level of seismic hazard at the Paducah Gaseous Diffusion Plant for policy considerations and engineering design is not an easy task because it not only depends on seismic hazard, but also on seismic risk and other related environmental, social, and economic issues. Seismic hazard is the main focus. There is no question that there are seismic hazards at the Paducah Gaseous Diffusion Plant because of its proximity to several known seismic zones, particularly the New Madrid Seismic Zone. The issues in estimating seismic hazard are (1) the methods being used and (2) difficulty in characterizing the uncertainties of seismic sources, earthquake occurrence frequencies, and ground-motion attenuation relationships. This report summarizes how input data were derived, which methodologies were used, and what the hazard estimates at the Paducah Gaseous Diffusion Plant are.

  2. Acoustic and Seismic Modalities for Unattended Ground Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Elbring, G.J.; Ladd, M.D.; McDonald, T.S.; Sleefe, G.E.

    1999-03-31

    In this paper, we have presented the relative advantages and complementary aspects of acoustic and seismic ground sensors. A detailed description of both acoustic and seismic ground sensing methods has been provided. Acoustic and seismic phenomenology including source mechanisms, propagation paths, attenuation, and sensing have been discussed in detail. The effects of seismo-acoustic and acousto-seismic interactions as well as recommendations for minimizing seismic/acoustic cross talk have been highlighted. We have shown representative acoustic and seismic ground sensor data to illustrate the advantages and complementary aspects of the two modalities. The data illustrate that seismic transducers often respond to acoustic excitation through acousto-seismic coupling. Based on these results, we discussed the implications of this phenomenology on the detection, identification, and localization objectives of unattended ground sensors. We have concluded with a methodology for selecting the preferred modality (acoustic and/or seismic) for a particular application.

  3. Expected Seismicity and the Seismic Noise Environment of Europa

    Science.gov (United States)

    Panning, Mark P.; Stähler, Simon C.; Huang, Hsin-Hua; Vance, Steven D.; Kedar, Sharon; Tsai, Victor C.; Pike, William T.; Lorenz, Ralph D.

    2018-01-01

    Seismic data will be a vital geophysical constraint on internal structure of Europa if we land instruments on the surface. Quantifying expected seismic activity on Europa both in terms of large, recognizable signals and ambient background noise is important for understanding dynamics of the moon, as well as interpretation of potential future data. Seismic energy sources will likely include cracking in the ice shell and turbulent motion in the oceans. We define a range of models of seismic activity in Europa's ice shell by assuming each model follows a Gutenberg-Richter relationship with varying parameters. A range of cumulative seismic moment release between 1016 and 1018 Nm/yr is defined by scaling tidal dissipation energy to tectonic events on the Earth's moon. Random catalogs are generated and used to create synthetic continuous noise records through numerical wave propagation in thermodynamically self-consistent models of the interior structure of Europa. Spectral characteristics of the noise are calculated by determining probabilistic power spectral densities of the synthetic records. While the range of seismicity models predicts noise levels that vary by 80 dB, we show that most noise estimates are below the self-noise floor of high-frequency geophones but may be recorded by more sensitive instruments. The largest expected signals exceed background noise by ˜50 dB. Noise records may allow for constraints on interior structure through autocorrelation. Models of seismic noise generated by pressure variations at the base of the ice shell due to turbulent motions in the subsurface ocean may also generate observable seismic noise.

  4. Penile vibratory stimulation in the recovery of urinary continence and erectile function after nerve‐sparing radical prostatectomy: a randomized, controlled trial

    National Research Council Canada - National Science Library

    Fode, Mikkel; Borre, Michael; Ohl, Dana A; Lichtbach, Jonas; Sønksen, Jens

    2014-01-01

    To examine the effect of penile vibratory stimulation (PVS) in the preservation and restoration of erectile function and urinary continence in conjunction with nerve-sparing radical prostatectomy (RP...

  5. Two-dimensional ground motion at a soft viscoelastic layer/hard substratum site in response to SH cylindrical seismic waves radiated by deep and shallow line sources-I. Theory

    Science.gov (United States)

    Groby, Jean-Philippe; Wirgin, Armand

    2005-10-01

    We consider, using theory (herein) and associated synthetic seismograms (in a companion paper), the seismic response of a site comprising a horizontal, homogeneous, soft viscoelastic layer of infinite lateral extent overlying, and in welded contact with, a homogeneous, hard elastic substratum of half-infinite radial extent. We show that for shear-horizontal motion: (1) coupling to Love modes is all the stronger the closer (in the vertical direction) the source (modelled as a line, assumed to lie in the substratum) is to the lower boundary of the soft layer, (2) all anomalous features (such as long duration) of the seismic wavefield, including those for regional earthquakes, are primarily the result of strong excitation of Love modes, (3) 1-D (body wave) type of response is: non-resonant, obtained for deep sources and usually characterized by relatively short durations, (4) for shallow sources and hypocentral distances that are not very large, the response results from a complex interplay of Love mode and body wave contributions, which requires a numerical description (furnished in the companion paper).

  6. Nationwide Assessment of Seismic Hazard for Georgia

    Science.gov (United States)

    Tsereteli, N. S.; Varazanashvili, O.; Mumladze, T.

    2014-12-01

    The work presents a framework for assessment of seismic hazards on national level for the Georgia. Based on a historical review of the compilation of seismic hazard zoning maps for the Georgia became evident that there were gaps in seismic hazard assessment and the present normative seismic hazard map needed a careful recalculation. The methodology for the probabilistic assessment of seismic hazard used here includes the following steps: produce comprehensive catalogue of historical earthquakes (up to 1900) and the period of instrumental observations with uniform scale of magnitudes; produce models of seismic source zones (SSZ) and their parameterization; develop appropriate ground motion prediction equation (GMPE) models; develop seismic hazard curves for spectral amplitudes at each period and maps in digital format. Firstly, the new seismic catalog of Georgia was created, with 1700 eqs from ancient times on 2012, Mw³4.0. Secondly, were allocated seismic source zones (SSZ). The identification of area SSZ was obtained on the bases of structural geology, parameters of seismicity and seismotectonics. In constructing the SSZ, the slope of the appropriate active fault plane, the width of the dynamic influence of the fault, power of seismoactive layer are taken into account. Finally each SSZ was defined with the parameters: the geometry, the percentage of focal mechanism, predominant azimuth and dip angle values, activity rates, maximum magnitude, hypocenter depth distribution, lower and upper seismogenic depth values. Thirdly, seismic hazard maps were calculated based on modern approach of selecting and ranking global and regional ground motion prediction equation for region. Finally, probabilistic seismic hazard assessment in terms of ground acceleration were calculated for the territory of Georgia. On the basis of obtained area seismic sources probabilistic seismic hazard maps were calculated showing peak ground acceleration (PGA) and spectral accelerations (SA) at

  7. Vibratory stimulation from powered-toothbrush: A novel approach for orthodontic pain reduction after initial archwire placement

    Directory of Open Access Journals (Sweden)

    Pradeep Raghav

    2015-01-01

    Full Text Available Introduction: Vibratory stimulation has been reported as an effective means in reducing the orthodontic pain. The aim of this study was to evaluate the effectiveness of vibratory stimulation from powered-toothbrushes as a noninvasive and nonpharmacological method of reducing pain caused after initial archwire placement and to compare it with other common modalities of management. Materials and Methods: This clinical trial included 75 patients of age 13–25 years, scheduled for fixed mechanotherapy. Patients were divided into five groups: Control, placebo multivitamin, paracetamol, chewing-gum (Cg, and powered-toothbrush. After placement of 0.016″ Nickel Titanium initial archwire (upper/lower in each patient, the discomfort perceived at 2 h, 6 h, bedtime, 24 h, 2 days, 3 days, and 7 days were marked individually using Wong-Baker (0–5 and numeric (0–10 pain rating scales. Kruskal–Wallis test, Friedman test, unpaired t-test were used for statistical analysis. Results: Vibratory stimulation from powered-toothbrushes effectively reduced pain after initial archwire placement. It did not alter the pattern of pain perception, but significantly reduced the overall intensity of pain at each time interval. Cg was not found effective enough to be recommended as a routine treatment modality. Conclusion: Powered-toothbrushes can be recommended as a nonpharmacological and noninvasive substitute for nonsteroidal anti-inflammatory drugs for effective pain reduction in the clinical practice.

  8. FDTD Seismic Simulation of Moving Tracked Vehicle

    National Research Council Canada - National Science Library

    Ketcham, Stephen

    2000-01-01

    This paper describes the utility of a large finite-difference time domain (FDTD) simulation of seismic wave propagation from a spatially and time varying source that generically represents a moving tracked vehicle...

  9. Advanced National Seismic System (ANSS) Comprehensive Catalog

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The ANSS Comprehensive Catalog (ComCat) contains earthquake source parameters and other products produced by contributing seismic networks. Important digital...

  10. First-order and subsidiary faults controlling the time-space evolution of the Central Italy 2016 seismic sequence - a multi-source data detailed 3D reconstruction

    Science.gov (United States)

    Lavecchia, Giusy; de nardis, Rita; Ferrarini, Federica; Cirillo, Daniele; Brozzetti, Francesco

    2017-04-01

    The Central Italy 2016 seismic sequence, with its three major events (24 August, Mw 6.0/6.2; 26 October Mw5.9/6.0; 30 October Mw6.5/6.6), activated a well-known active west-dipping extensional fault alignment of central Italy (Vettore-Gorzano faults, VEGO). Soon after the first event, based on geological, interferometric and at that moment available seismological data, a preliminary 3D fault model of VEGO was built. Such a model is here updated and improved at the light of a large amount of relocated earthquake data (time interval 24 August to 30 November 2016, 0.1≤ML ≤6.5, Chiaraluce at al., submitted to SRL) plus additional geological information. The 3D modeling was done using the software package MOVE from the Midland Valley. All the available data were taken into consideration (surface traces, fault-slip data, primary co-seismic surface fractures, geological maps and cross-sections, hypocentral locations and focal mechanisms of both background seismicity and seismic sequences). The VEGO geometric configuration did not substantially changed with respect to the previous model, but some additional structures involved in the sequence were reconstructed. In particular, four additional faults are well evident: a NE-dipping normal fault (dip-angle 50˚ ) antithetic to Vettore Fault, located at depths between 1 and 5 km; a WNW dipping plane (dip-angle 30˚ ) located at depth between 1 and 4 km within the Vettore footwall volume; this structure represents a splay of the late Miocene Sibillini thrust, which is evidently cross-cut and dislocated by the Vettore normal fault; a SW-dipping normal fault representing an unknown northward prosecution of the VEGO alignment, where since 26 October a relevant seismic activity was released; an unknown east-dipping low-angle detachment, where VEGO detaches at a depth of about 10-11 km. An uninterrupted microseismic activity has illuminated such a detachment not only during the overall sequence, but also in the previous months

  11. Advanced Seismic While Drilling System

    Energy Technology Data Exchange (ETDEWEB)

    Robert Radtke; John Fontenot; David Glowka; Robert Stokes; Jeffery Sutherland; Ron Evans; Jim Musser

    2008-06-30

    A breakthrough has been discovered for controlling seismic sources to generate selectable low frequencies. Conventional seismic sources, including sparkers, rotary mechanical, hydraulic, air guns, and explosives, by their very nature produce high-frequencies. This is counter to the need for long signal transmission through rock. The patent pending SeismicPULSER{trademark} methodology has been developed for controlling otherwise high-frequency seismic sources to generate selectable low-frequency peak spectra applicable to many seismic applications. Specifically, we have demonstrated the application of a low-frequency sparker source which can be incorporated into a drill bit for Drill Bit Seismic While Drilling (SWD). To create the methodology of a controllable low-frequency sparker seismic source, it was necessary to learn how to maximize sparker efficiencies to couple to, and transmit through, rock with the study of sparker designs and mechanisms for (a) coupling the sparker-generated gas bubble expansion and contraction to the rock, (b) the effects of fluid properties and dynamics, (c) linear and non-linear acoustics, and (d) imparted force directionality. After extensive seismic modeling, the design of high-efficiency sparkers, laboratory high frequency sparker testing, and field tests were performed at the University of Texas Devine seismic test site. The conclusion of the field test was that extremely high power levels would be required to have the range required for deep, 15,000+ ft, high-temperature, high-pressure (HTHP) wells. Thereafter, more modeling and laboratory testing led to the discovery of a method to control a sparker that could generate low frequencies required for deep wells. The low frequency sparker was successfully tested at the Department of Energy Rocky Mountain Oilfield Test Center (DOE RMOTC) field test site in Casper, Wyoming. An 8-in diameter by 26-ft long SeismicPULSER{trademark} drill string tool was designed and manufactured by TII

  12. System Modeling of a MEMS Vibratory Gyroscope and Integration to Circuit Simulation.

    Science.gov (United States)

    Kwon, Hyukjin J; Seok, Seyeong; Lim, Geunbae

    2017-11-18

    Recently, consumer applications have dramatically created the demand for low-cost and compact gyroscopes. Therefore, on the basis of microelectromechanical systems (MEMS) technology, many gyroscopes have been developed and successfully commercialized. A MEMS gyroscope consists of a MEMS device and an electrical circuit for self-oscillation and angular-rate detection. Since the MEMS device and circuit are interactively related, the entire system should be analyzed together to design or test the gyroscope. In this study, a MEMS vibratory gyroscope is analyzed based on the system dynamic modeling; thus, it can be mathematically expressed and integrated into a circuit simulator. A behavioral simulation of the entire system was conducted to prove the self-oscillation and angular-rate detection and to determine the circuit parameters to be optimized. From the simulation, the operating characteristic according to the vacuum pressure and scale factor was obtained, which indicated similar trends compared with those of the experimental results. The simulation method presented in this paper can be generalized to a wide range of MEMS devices.

  13. Two Novel Measurements for the Drive-Mode Resonant Frequency of a Micromachined Vibratory Gyroscope

    Directory of Open Access Journals (Sweden)

    Ancheng Wang

    2013-11-01

    Full Text Available To investigate the drive-mode resonance frequency of a micromachined vibratory gyroscope (MVG, one needs to measure it accurately and efficiently. The conventional approach to measure the resonant frequency is by performing a sweep frequency test and spectrum analysis. The method is time-consuming and inconvenient because of the requirements of many test points, a lot of data storage and off-line analyses. In this paper, we propose two novel measurement methods, the search method and track method, respectively. The former is based on the magnitude-frequency characteristics of the drive mode, utilizing a one-dimensional search technique. The latter is based on the phase-frequency characteristics, applying a feedback control loop. Their performances in precision, noise resistivity and efficiency are analyzed through detailed simulations. A test system is implemented based on a field programmable gate array (FPGA and experiments are carried out. By comparing with the common approach, feasibility and superiorities of the proposed methods are validated. In particular, significant efficiency improvements are achieved whereby the conventional frequency method consumes nearly 5,000 s to finish a measurement, while only 5 s is needed for the track method and 1 s for the search method.

  14. System Modeling of a MEMS Vibratory Gyroscope and Integration to Circuit Simulation

    Directory of Open Access Journals (Sweden)

    Hyukjin J. Kwon

    2017-11-01

    Full Text Available Recently, consumer applications have dramatically created the demand for low-cost and compact gyroscopes. Therefore, on the basis of microelectromechanical systems (MEMS technology, many gyroscopes have been developed and successfully commercialized. A MEMS gyroscope consists of a MEMS device and an electrical circuit for self-oscillation and angular-rate detection. Since the MEMS device and circuit are interactively related, the entire system should be analyzed together to design or test the gyroscope. In this study, a MEMS vibratory gyroscope is analyzed based on the system dynamic modeling; thus, it can be mathematically expressed and integrated into a circuit simulator. A behavioral simulation of the entire system was conducted to prove the self-oscillation and angular-rate detection and to determine the circuit parameters to be optimized. From the simulation, the operating characteristic according to the vacuum pressure and scale factor was obtained, which indicated similar trends compared with those of the experimental results. The simulation method presented in this paper can be generalized to a wide range of MEMS devices.

  15. Separation of water from metal working emulsions by ultrafiltration using vibratory membranes.

    Science.gov (United States)

    Moulai-Mostefa, Nadji; Frappart, Matthieu; Akoum, Omar; Ding, Luhui; Jaffrin, Michel Y

    2010-05-15

    In this paper, we investigate the application of a vibratory shear-enhanced filtration system (VSEP) to separation of water from oil-in-water emulsions. The VSEP module consists in an annular membrane of 500 cm(2) area which oscillates azimuthally in its own plane with an amplitude depending upon frequency. Polyethersulfone (PES) membranes of 50 and 20 kDa were used. Test fluids consisted of oil-in-water emulsion at an oil concentration of 4% prepared from a concentrated cutting fluid. The critical flux for stable operation was investigated by increasing the permeate flux in steps while monitoring the transmembrane pressure (TMP). With a 50 kDa membrane the flux increased nonlinearly with TMP and reached 250 L h(-1)m(-2) at a TMP of 1500 kPa while permeate turbidity decayed from 1.8 to 0.9 NTU above 600 kPa from an initial emulsion turbidity of 21,900 NTU. With the 20 kDa membrane, the flux increased linearly with TMP until 1600 kPa, but the oil concentration in permeate became negligible (turbidity near zero NTU). Concentration tests showed that the flux decreased linearly with ln(VRR) where VRR is the volume reduction ratio while permeate turbidity increased exponentially to 25NTU above a VRR of 4. This work confirms the high performance of the VSEP for oil separation from water in metal working emulsions. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  16. Penile vibratory stimulation and electroejaculation before anticancer therapy in two pubertal boys.

    Science.gov (United States)

    Schmiegelow, M L; Sommer, P; Carlsen, E; Sønksen, J O; Schmiegelow, K; Müller, J R

    1998-01-01

    Because more than 70% of children with cancer become long-term survivors, more emphasis is put on reducing late effects. Cryopreservation of semen and the intracytoplasmic sperm injection technique makes it possible to obtain pregnancy with very poor sperm quality. Two new semen retrieval methods are described that are applicable in pubertal boys with a fertility potential, although not psychologically ready to produce a semen sample, who are likely to become infertile because of anticancer therapy. Two pubertal boys (aged 14 and 15 years) had a late testicular relapse of pre-B acute lymphoblastic leukemia and Hodgkin disease, stage II, respectively. In patient 1, penile vibratory stimulation (PVS) was tried under general anesthesia without success and electroejaculation (EEJ) was performed. Before alkylating chemotherapy and testicular irradiation, PVS was performed with success in patient 2. An antegrade ejaculate of 0.7 ml with 1% motile spermatozoa and an retrograde ejaculate with 1.6 x 10(6)/ml spermatozoa (5% with fair motility) was obtained from patient 1. An antegrade ejaculate of 1.5 ml with 2.5 x 10(6)/ml spermatozoa (29% with fair motility) was obtained from patient 2. PVS should be the first choice of treatment because it is noninvasive, simple, and easily applied. Because EEJ requires general anesthesia, it should be used as a second option.

  17. Penile vibratory stimulation in the treatment of post-prostatectomy incontinence

    DEFF Research Database (Denmark)

    Fode, Mikkel; Sønksen, Jens

    2015-01-01

    AIMS: To examine penile vibratory stimulation (PVS) in the treatment of post-prostatectomy urinary incontinence (UI). METHODS: Patients with post-prostatectomy UI were included in a 12-week trial. A 24-hr pad test and a 72-hr voiding diary were collected at baseline. Participants were randomized...... men were available for analyses. The difference in the change on the pad test between the groups did not reach statistical significance at 6 weeks (P = 0.13) while the change in incontinence episodes between groups approached statistical significance (P = 0.052). However, there was a median reduction...... of -33 g (P = 0.021) on the pad test and a median reduction in daily incontinence episodes of -1 (P = 0.023) in group 1 at 6 weeks. At 12 weeks, group 2 had a median decrease on the pad test of -8 g (P = 0.10) and no change in incontinence episodes. A pooled analysis showed a decline on the pad test...

  18. Integrated seismic monitoring in Slovakia

    Science.gov (United States)

    Bystrický, E.; Kristeková, M.; Moczo, P.; Cipciar, A.; Fojtíková, L.; Pažák, P.; Gális, M.

    2009-04-01

    Two seismic networks are operated on the territory of the Slovak republic by two academic institutions. The Geophysical Institute of the Slovak Academy of Sciences operates the Slovak National Network of Seismic Stations (SNNSS, established in 2004) and the Faculty of Mathematics, Physics and Informatics, Comenius University Bratislava operates the Local Seismic Network Eastern Slovakia (LSNES, established in 2007). SNNSS is focused on the regional seismicity and participates in the international data exchange on a regular basis. LSNES, designed to be compatible and complementary with the existing SNNSS infrastructure, is focused on the seismicity of the eastern Slovakia source zone. The two networks share database and archive. Thus the expenses and workload of the joint data center operation are split between the two institutions. The cooperation enhances the overall reliability of the data center while does not interfere with the original scopes of the two networks. Relational database with thin client based on the standard web browser is implemented. Maintenance requirements of clients are reduced to minimum and it is easier to manage the system integrity. The database manages parametric data, macroseismic data, waveform data, inventory data, and geographic data. The database is not only a central part of the data processing of the two institutions; it also forms a core of the warning system. The warning system functionality requires development of the modules which are additional to the standard seismic database functionality. The modules for editing, publishing and automatic processing of macroseismic questionnaires were implemented for the purpose of the warning system, and the database integrates macroseismic data with other seismic data.

  19. Evaluation of the seismic hazard for 20 cities in Romania using Monte Carlo based simulations

    Science.gov (United States)

    Pavel, Florin; Vacareanu, Radu

    2017-07-01

    This work focuses on the evaluation of the seismic hazard for Romania using earthquake catalogues generated by a Monte Carlo approach. The seismicity of Romania can be attributed to the Vrancea intermediate-depth seismic source and to 13 other crustal seismic sources. The recurrence times of large magnitude seismic events (both crustal and subcrustal), as well as the moment release rates are computed using simulated earthquake catalogues. The results show that the largest contribution to the overall moment release for the crustal seismic sources is from the seismic regions in Bulgaria, while the seismic regions in Romania contribute less than 5% of the overall moment release. In addition, the computations show that the moment release rate for the Vrancea subcrustal seismic source is about ten times larger than that of all the crustal seismic sources. Finally, the Monte Carlo approach is used to evaluate the seismic hazard for 20 cities in Romania with populations larger than 100,000 inhabitants. The results show some differences between the seismic hazard values obtained through Monte-Carlo simulation and those in the Romanian seismic design code P100-1/2013, notably for cities situated in the western part of Romania that are influenced by local crustal seismic sources.

  20. AcquisitionFootprintAttenuationDrivenbySeismicAttributes

    Directory of Open Access Journals (Sweden)

    Cuellar-Urbano Mayra

    2014-04-01

    Full Text Available Acquisition footprint, one of the major problems that PEMEX faces in seismic imaging, is noise highly correlated to the geometric array of sources and receivers used for onshore and offshore seismic acquisitions. It prevails in spite of measures taken during acquisition and data processing. This pattern, throughout the image, is easily confused with geological features and misguides seismic attribute computation. In this work, we use seismic data from PEMEX Exploración y Producción to show the conditioning process for removing random and coherent noise using linear filters. Geometric attributes used in a workflow were computed for obtaining an acquisition footprint noise model and adaptively subtract it from the seismic data.

  1. Study of modern seismic zoning maps' accuracy (case for Eastern Uzbekistan

    Directory of Open Access Journals (Sweden)

    T.U. Artikov

    2016-11-01

    Full Text Available Influence of uncertainty factors of input parameters on results of the estimation of seismic hazard has been researched. It is found that the largest deviations, from seismic hazard maps designed on the basis of average values of distribution of seismic mode and seismic load parameters, may arise due to the imprecise depth of earthquake sources (H, uncertain estimations of seismic potential (Мmax and slope of recurrence curve (γ. The contribution of such uncertainty factors, like imprecise definition of seismic activity А10, incorrect choice of prevailing type of a motion in the source, using regional laws of attenuation of seismic load intensity in distance instead of local once are substantially small. For Eastern Uzbekistan, it was designed the seismic hazard map with the highest value which takes into account every possible factors of uncertainty in parameters of seismic mode and seismic load.

  2. Seismic and hydroacoustic investigations near Ascension Island

    Science.gov (United States)

    Hanson, Jeffrey Acton

    A local seismicity study is conducted observing earthquakes near Ascension Island including a segment of the Mid-Atlantic Ridge (MAR). We use data collected from permanently deployed hydroacoustic and seismic instruments over a 2 year period to determine patterns in the ridge seismicity. Earthquakes are observed on the MAR 1 to 2 orders of magnitude smaller than the global catalogs can in this part of the world. Epicenters are determined for 77 of the events using the seismic and hydroacoustic data. Ridge seismicity is mainly confined to the median valley although systematic errors could give mislocations up to 10 km in one direction. The seismicity is infrequent at the segment center and increases towards the segment ends. Seismicity is not seen at the inside corner high. We do not observe direct evidence for seismicity along an anomalous shallow section of the MAR which also appears aseismic in the global catalogs. A simple method is described whereby station-to-source azimuths are estimated by fitting a plane wave to envelope functions of T-phases observed on 5 hydrophones surrounding Ascension Island, South Atlantic Ocean. When applied to a data set of 55 earthquakes with T-phases observed on at least 3 instruments, estimated azimuths have a standard deviation of 3.6 degrees compared to azimuths predicted from global catalog epicentral locations. The standard deviation decreases to 2 degrees if T-phase data from all 5 hydrophones are used. The performance of a seismic T-phase station for recording hydroacoustic phases is examined by comparing seismic and hydrophone T-phases from MAR earthquakes at Ascension Island. Variations between the corrected hydroacoustic amplitudes and seismic amplitudes are compared with physical parameters such as the gradient of the topography at the island-ocean interface. T-phases can have various modal structures which will couple into the island differently. Thus events from the same direction have different signal loss.

  3. Penile vibratory stimulation in the treatment of post-prostatectomy incontinence: a randomized pilot study.

    Science.gov (United States)

    Fode, Mikkel; Sønksen, Jens

    2015-02-01

    To examine penile vibratory stimulation (PVS) in the treatment of post-prostatectomy urinary incontinence (UI). Patients with post-prostatectomy UI were included in a 12-week trial. A 24-hr pad test and a 72-hr voiding diary were collected at baseline. Participants were randomized to receive PVS for the first 6 weeks (group 1) or for the final 6 weeks (group 2) of the study. The primary outcome was the difference in leakage between groups 1 and 2 at 6 weeks as measured by changes in the pad test. The trial was registered at www.clinicaltrials.org (NCT01540656). Data from 31 men were available for analyses. The difference in the change on the pad test between the groups did not reach statistical significance at 6 weeks (P = 0.13) while the change in incontinence episodes between groups approached statistical significance (P = 0.052). However, there was a median reduction of -33 g (P = 0.021) on the pad test and a median reduction in daily incontinence episodes of -1 (P = 0.023) in group 1 at 6 weeks. At 12 weeks, group 2 had a median decrease on the pad test of -8 g (P = 0.10) and no change in incontinence episodes. A pooled analysis showed a decline on the pad test of -13.5 g (P = 0.004) after PVS. Small improvements were seen in subjective symptom scores and 58% stated to be satisfied with PVS. Self-limiting side effects were experienced by 15% of patients. PVS is feasible in the treatment of post-prostatectomy UI. Larger trials are needed to document the clinical efficacy. © 2013 Wiley Periodicals, Inc.

  4. Effect of Axial Force on the Performance of Micromachined Vibratory Rate Gyroscopes

    Directory of Open Access Journals (Sweden)

    Zhengyi Niu

    2010-12-01

    Full Text Available It is reported in the published literature that the resonant frequency of a silicon micromachined gyroscope decreases linearly with increasing temperature. However, when the axial force is considerable, the resonant frequency might increase as the temperature increases. The axial force is mainly induced by thermal stress due to the mismatch between the thermal expansion coefficients of the structure and substrate. In this paper, two types of micromachined suspended vibratory gyroscopes with slanted beams were proposed to evaluate the effect of the axial force. One type was suspended with a clamped-free (C-F beam and the other one was suspended with a clamped-clamped (C-C beam. Their drive modes are the bending of the slanted beam, and their sense modes are the torsion of the slanted beam. The relationships between the resonant frequencies of the two types were developed. The prototypes were packaged by vacuum under 0.1 mbar and an analytical solution for the axial force effect on the resonant frequency was obtained. The temperature dependent performances of the operated mode responses of the micromachined gyroscopes were measured. The experimental values of the temperature coefficients of resonant frequencies (TCF due to axial force were 101.5 ppm/°C for the drive mode and 21.6 ppm/°C for the sense mode. The axial force has a great influence on the modal frequency of the micromachined gyroscopes suspended with a C-C beam, especially for the flexure mode. The quality factors of the operated modes decreased with increasing temperature, and changed drastically when the micromachined gyroscopes worked at higher temperatures.

  5. Effect of axial force on the performance of micromachined vibratory rate gyroscopes.

    Science.gov (United States)

    Hou, Zhanqiang; Xiao, Dingbang; Wu, Xuezhong; Dong, Peitao; Chen, Zhihua; Niu, Zhengyi; Zhang, Xu

    2011-01-01

    It is reported in the published literature that the resonant frequency of a silicon micromachined gyroscope decreases linearly with increasing temperature. However, when the axial force is considerable, the resonant frequency might increase as the temperature increases. The axial force is mainly induced by thermal stress due to the mismatch between the thermal expansion coefficients of the structure and substrate. In this paper, two types of micromachined suspended vibratory gyroscopes with slanted beams were proposed to evaluate the effect of the axial force. One type was suspended with a clamped-free (C-F) beam and the other one was suspended with a clamped-clamped (C-C) beam. Their drive modes are the bending of the slanted beam, and their sense modes are the torsion of the slanted beam. The relationships between the resonant frequencies of the two types were developed. The prototypes were packaged by vacuum under 0.1 mbar and an analytical solution for the axial force effect on the resonant frequency was obtained. The temperature dependent performances of the operated mode responses of the micromachined gyroscopes were measured. The experimental values of the temperature coefficients of resonant frequencies (TCF) due to axial force were 101.5 ppm/°C for the drive mode and 21.6 ppm/°C for the sense mode. The axial force has a great influence on the modal frequency of the micromachined gyroscopes suspended with a C-C beam, especially for the flexure mode. The quality factors of the operated modes decreased with increasing temperature, and changed drastically when the micromachined gyroscopes worked at higher temperatures.

  6. A randomized trial of clitoral vacuum suction versus vibratory stimulation in neurogenic female orgasmic dysfunction.

    Science.gov (United States)

    Alexander, Marcalee; Bashir, Khurram; Alexander, Craig; Marson, Lesley; Rosen, Raymond

    2017-09-09

    To examine safety and efficacy of use of a clitoral vacuum suction device (CVSD) versus vibratory stimulation (V) to treat orgasmic dysfunction in women with MS or SCI. Randomized clinical trial. Two academic medical centers. Thirty-one women including 20 with MS and 11 with SCI. A 12-week trial of the use of a CVSD versus V MAIN OUTCOME MEASURES: Female Sexual Function Inventory (FSFI) and Female Sexual Distress Scale (FSDS). 23 women (18 MS; 5 SCI) completed the study including 13/16 randomized to CVSD and 10/15 randomized to V. There was a statistically significant increase in total FSFI score (p=.011), desire (p=. 009), arousal (p=.009), lubrication (p=.008), orgasm (p=.012), and satisfaction (p=.049) and a significant decrease in distress as measured by FSDS (p=.020) in subjects using the CVSD. In subjects who used V, there was a statistically significant increase in the orgasm subscale of the FSFI (p=.028). Subjects using the CVSD maintained improvements 4 weeks after treatment. CVSD is safe and overall efficacious to treat female neurogenic sexual dysfunction related to MS and SCI. V is also safe and efficacious to female neurogenic orgasmic dysfunction; however, results were limited to the active treatment period. Due to ease of access and cost, clinicians can consider use of V for women with MS or SCI with orgasmic dysfunction. CVSD is recommended for women with multiple sexual dysfunctions or for whom V is ineffective. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  7. Development and evaluation of a vibratory-pneumatic pomegranate arils extractor

    Directory of Open Access Journals (Sweden)

    S. M Nassiri

    2017-05-01

    Full Text Available Introduction Iran is a frontier of pomegranate fruit production in the world (with almost 40 % of the world`s production. However due to traditional processing operations is not ranked as the largest pomegranate exporter. Saveh, Neyriz and Ferdows are the top pomegranate producing cities in Iran. Pomegranate is consumed as a fresh fruit as well as processed product as food additive, paste, syrup, jelly, pectin, jam, beverage, essence, vinegar and concentrate. Aril extraction is the first and essential postharvest operation for pomegranate processing. Arils are mostly extracted manually even in large scales for fresh and processed consumption. This labor intensive operation is rational when aril quality is an important index for consumer. But whenever pomegranate juice is desired, the aril quality has no priority for consumer, and therefore arils can be extracted with less care. Sarig (1985 was the first inventor of a pomegranate aril extractor who employed air jet force to extract the arils. Later, other researchers employed the same method as well as water jet to extract fruit juice and sac. In the present study, fabrication and evaluation of vibratory aril extractor augmented with air system was conducted. Materials and Methods The study was conducted using Rabab cultivar samples which were manually harvested from an orchard in Neyriz town, Fars province. Samples were kept in refrigerator at 5 0C till experimental trials. Initial moisture content of fruit skin, arils and internal fleshes were measured by gravimetric method as 31.7±2.6 %, 61.5±1.8 % and 42.8±1.4 %, respectively and for a whole fruit was measured 45.3±11.5 % (w.b.. For conducting laboratory tests, an aril extraction unit was designed and fabricated. It comprised a steel main frame, a 746 W electric motor, drive mechanism (eccentric and shaft, sample retentive unit, air jet unit, aril tank, and an air compressor-tank assembly. Sample retentive unit was designed in such a

  8. sources

    Directory of Open Access Journals (Sweden)

    Shu-Yin Chiang

    2002-01-01

    Full Text Available In this paper, we study the simplified models of the ATM (Asynchronous Transfer Mode multiplexer network with Bernoulli random traffic sources. Based on the model, the performance measures are analyzed by the different output service schemes.

  9. Implementation of the resonant vibratory feeders control algorithm on Simatic S7-1200 from MATLAB Simulink enviroment

    Directory of Open Access Journals (Sweden)

    Mitrović Radomir B.

    2016-01-01

    Full Text Available Simulink is an important tool for modeling and simulation of process and control algorithms. It's expansion, PLC Coder, enables direct conversion of model subsystem into SCL, structured text code, which is then used by PLC IDE to create function blocks. This shortens developing time of algorithms for PLC controller. Also, this reduces possibility for a coding error. This paper describes Simulink PLC Coder and workflow for developing PID control algorithm for Siemens Simatic S7-1200 PLC. Control object used here is resonant vibratory feeder having electromagnetic drive.

  10. Penile vibratory stimulation in the recovery of urinary continence and erectile function after nerve-sparing radical prostatectomy

    DEFF Research Database (Denmark)

    Fode, Mikkel; Borre, Michael; Ohl, Dana A

    2014-01-01

    OBJECTIVE: To examine the effect of penile vibratory stimulation (PVS) in the preservation and restoration of erectile function and urinary continence in conjunction with nerve-sparing radical prostatectomy (RP). PATIENTS AND METHODS: The present study was conducted between July 2010 and March 2013...... and 12 months after surgery with the IIEF-5 questionnaire and questions regarding urinary bother. Patients using up to one pad daily for security reasons only were considered continent. The study was registered at http://clinicaltrials.gov/ (NCT01067261). RESULTS: Data from 68 patients were available...

  11. Seismic risk perception test

    Science.gov (United States)

    Crescimbene, Massimo; La Longa, Federica; Camassi, Romano; Pino, Nicola Alessandro

    2013-04-01

    population and territory); seismic risk in general; risk information and their sources; comparison between seismic risk and other natural hazards. Informative data include: Region, Province, Municipality of residence, Data compilation, Age, Sex, Place of Birth, Nationality, Marital status, Children, Level of education, Employment. The test allows to obtain the perception score for each factor: Hazard, Exposed value, Vulnerability. These scores can be put in relation with the scientific data relating to hazard, vulnerability and the exposed value. On January 2013 started a Survey in the Po Valley and Southern Apennines. The survey will be conducted via web using institutional sites of regions, provinces, municipalities, online newspapers to local spreading, etc. Preliminary data will be discussed. Improve our understanding of the perception of seismic risk would allow us to inform more effectively and to built better educational projects to mitigate risk.

  12. Analyses of seismic activities and hazards in Laos: A seismicity approach

    Directory of Open Access Journals (Sweden)

    Santi Pailoplee Punya Charusiri

    2017-01-01

    Full Text Available The seismic activities and hazards in People’s Democratic Republic Laos were analyzed using the most up-to-date seismicity data. Both the a- and b-values of the frequency-magnitude distribution model, including the return period of earthquake magnitude in the range of 5.0 - 6.0 Mw, were evaluated spatially in a region that ex­tends 300 km from Laos. Six seismic source zones with different seismic activities were found. Based on these seismic source zones and a suitable attenuation model, seismic hazards were then analyzed in both deterministic and probabilistic scenarios. The deterministic map showed a possible maximum ground shaking up to 0.4 g in Northern Laos, whereas the ground shaking calculated from the probabilistic ap­proach was 90, 70 - 90, and 20 - 40%, respectively, and was higher in the northern part. From these seismic activities and hazard analyses, Laos can be clearly separated into the three hazard zones of north­western, northeastern and southern Laos with a high, medium and low earthquake hazard, respectively. Therefore, effective mitigation plans to reduce the impact of seismic hazards should be formulated and in particular for a number of major prov­inces located in the northern part of Laos.

  13. Sources

    OpenAIRE

    2015-01-01

    Sources Fondation Pablo Iglesias. Alcala de Henares. Sections : Archives privées de Manuel ArijaArchives extérieuresArchives FNJS de EspañaPrensa Archives Générales de l’Administration. Alcala de Henares. Sections : Opposition au franquismeSig. 653 Sig TOP 82/68.103-68.602.Índice de las cartas colectivas, Relaciones, Cartas al Ministro de Información de Marzo de 1965. c.662. Sources cinématographiques Filmothèque Nationale d’Espagne.NO.DO. N° 1157C. 08/03/1965.aguirre Javier, Blanco vertical....

  14. Assessing submarine gas hydrate at active seeps on the Hikurangi Margin, New Zealand, using controlled source electromagnetic data with constraints from seismic, geochemistry, and heatflow data

    Science.gov (United States)

    Schwalenberg, K.; Haeckel, M.; Pecher, I. A.; Toulmin, S. J.; Hamdan, L. J.; Netzeband, G.; Wood, W.; Poort, J.; Jegen, M. D.; Coffin, R. B.

    2009-12-01

    Electrical resistivity is one of the key properties useful for evaluating submarine gas hydrate deposits. Gas hydrates are electrically insulating in contrast to the conductive pore fluid. Where they form in sufficient quantities the bulk resistivity of the sub-seafloor is elevated. CSEM data were collected in 2007 as part of the German - International “New Vents” project on R/V Sonne, cruise SO191, at three target areas on the Hikurangi subduction margin, New Zealand. The margin is characterized by widespread bottom simulating reflectors (BSR), seep structures, and active methane and fluid venting indicating the potential for gas hydrate formation. Opouawe Bank is one of the ridge and basin systems on the accretionary wedge and is located off the Wairarapa coast at water depths of 1000-1100 m. The first observed seep sites (North Tower, South Tower, Pukeko, Takahe, and Tui) were identified from individual gas flares in hydro-acoustic data and video observations during voyages on R/V Tangaroa. Seismic reflection data collected during SO191 subsequently identified more than 25 new seep structures. Two intersecting CSEM profiles have been surveyed across North Tower, South Tower, and Takahe. 1-D inversion of the data reveals anomalously high resistivities at North Tower and South Tower, moderately elevated resistivities at Takahe, and normal background resistivities away from the seeps. The high resistivities are attributed to gas hydrate layers at intermediate depths beneath the seeps. At South Tower the hydrate concentration could be possibly as much as 25% of the total sediment volume within a 50m thick layer. This conforms with geochemical pore water analyses which show a trend of increased methane flux towards South Tower. At Takahe, gas pockets and patchy gas hydrate, as well as sediment heterogeneities and carbonates, or temperature driven upward fluid flow indicated by the observed higher heat flow at this site may explain the resistivity pattern

  15. Characterization of the seismic environment at the Sanford Underground Laboratory, South Dakota

    Energy Technology Data Exchange (ETDEWEB)

    Harms, J; Dorsher, S; Kandhasamy, S; Mandic, V [University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); Acernese, F; Barone, F [Universita degli Studi di Salerno, Fisciano (Saudi Arabia) (Italy); Bartos, I; Marka, S [Columbia University, New York, NY 10027 (United States); Beker, M; Van den Brand, J F J; Rabeling, D S [Nikhef, National Institute for Subatomic Physics, Science Park 105, 1098 XG Amsterdam (Netherlands); Christensen, N; Coughlin, M [Carleton College, Northfield, MN 55057 (United States); DeSalvo, R [California Institute of Technology, Pasadena, CA 91125 (United States); Heise, J; Trancynger, T [Sanford Underground Laboratory, 630 East Summit Street, Lead, SD 57754 (United States); Mueller, G [University of Florida, Gainesville, FL 32611 (United States); Naticchioni, L [Department of Physics, University of Rome ' Sapienza' , P.le Aldo Moro 2, 00185 Rome (Italy); O' Keefe, T [Saint Louis University, 3450 Lindell Blvd., St. Louis, MO 63103 (United States); Sajeva, A, E-mail: janosch@caltech.ed [Dipartimento di Fisica ' Enrico Fermi' , Universita di Pisa, Largo Bruno Pontecorvo, Pisa (Italy)

    2010-11-21

    An array of seismometers is being developed at the Sanford Underground Laboratory, the former Homestake mine, in South Dakota to study the properties of underground seismic fields and Newtonian noise, and to investigate the possible advantages of constructing a third-generation gravitational-wave detector underground. Seismic data were analyzed to characterize seismic noise and disturbances. External databases were used to identify sources of seismic waves: ocean-wave data to identify sources of oceanic microseisms and surface wind-speed data to investigate correlations with seismic motion as a function of depth. In addition, sources of events contributing to the spectrum at higher frequencies are characterized by studying the variation of event rates over the course of a day. Long-term observations of spectral variations provide further insight into the nature of seismic sources. Seismic spectra at three different depths are compared, establishing the 4100 ft level as a world-class low seismic-noise environment.

  16. Seismic tomography inversion in the case that sources and receivers are distributed out of a 2-D plane; Shingen jushinten ga nijigen heimennai ni nai baai no danseiha tomography kaiseki ni kansuru kosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Yokota, T.; Miyazaki, T. [Geological Survey of Japan, Tsukuba (Japan); Rokugawa, S.; Matsushima, J. [The University of Tokyo, Tokyo (Japan). Faculty of Engineering; Ashida, Y. [Kyoto University, Kyoto (Japan). Faculty of Engineering

    1996-10-01

    In the case where sources and receivers are not distributed on a 2-D plane, seismic tomography inversion was studied. In tomography experiments, the existing wells are generally used. In such case, sources and receivers are frequently not distributed on a 2-D plane. The 2.5-D analysis method including 2-D structure and 3-D ray-tracing was thus developed. This method is featured by less memory necessary for ray-tracing calculation, and the same algorithm for velocity determination as 2-D analysis method. In previous methods, since analysis is generally carried out by projecting sources and receivers on a certain assumed 2-D plane, it can derive correct results in the case of constant velocity and straight ray, however, in the other case, it derives incorrect results. Application of 3-D tomography requires a large amount of memory, and falls into poor convergence because of various parameters. The 2.5-D analysis method can avoid these demerits. This analysis method was applied to the data obtained in Ogiri area, Kagoshima prefecture. 5 refs., 3 figs., 2 tabs.

  17. Seismic hazard in the Nation's breadbasket

    Science.gov (United States)

    Boyd, Oliver; Haller, Kathleen; Luco, Nicolas; Moschetti, Morgan P.; Mueller, Charles; Petersen, Mark D.; Rezaeian, Sanaz; Rubinstein, Justin L.

    2015-01-01

    The USGS National Seismic Hazard Maps were updated in 2014 and included several important changes for the central United States (CUS). Background seismicity sources were improved using a new moment-magnitude-based catalog; a new adaptive, nearest-neighbor smoothing kernel was implemented; and maximum magnitudes for background sources were updated. Areal source zones developed by the Central and Eastern United States Seismic Source Characterization for Nuclear Facilities project were simplified and adopted. The weighting scheme for ground motion models was updated, giving more weight to models with a faster attenuation with distance compared to the previous maps. Overall, hazard changes (2% probability of exceedance in 50 years, across a range of ground-motion frequencies) were smaller than 10% in most of the CUS relative to the 2008 USGS maps despite new ground motion models and their assigned logic tree weights that reduced the probabilistic ground motions by 5–20%.

  18. Use Videostrobokymography to Quantitatively Analyze the Vibratory Characteristics Before and After Conservative Medical Treatment of Vocal Fold Leukoplakia.

    Science.gov (United States)

    Gao, Xiao-Wei; Huang, Yong-Wang; Liu, Li-Yan; Ouyang, Jie

    2016-03-01

    To quantitatively analyze the vibratory characteristics of vocal folds before and after conservative treatments to evaluate the outcomes of conservative treatments for vocal fold leukoplakia using videostrobokymography (VSK). This is a prospective study. Twenty patients and 20 controls were enrolled into the study. All patients received conservative treatments for 3 weeks and received VSK examination before and 3 weeks after the treatments. All controls only received VSK examination once. Vocal fold lengths of 25%, 50%, and 75% were chosen as the line-scan positions to evaluate the vocal fold vibration. Open quotient (OQ) and asymmetry index (AI) were obtained using VSK. Significant improvements in the main symptoms including voice hoarseness were found. Videostroboscopic findings showed that the white lesions on the vocal folds almost completely disappeared in all patients, and the vocal fold flexibility returned to normal. All OQs and AIs at each line-scan position in patients before the treatments were larger than those in controls (P  0.017). VSK could quantitatively evaluate the vibratory characteristics of vocal folds before and after the treatments, and conservative treatment could improve VSK measurements to normal control values, suggesting that VSK is a tool to assess the outcomes of the conservative treatments for vocal fold leukoplakia. Copyright © 2016 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

  19. Atmospheric-Seismic Effect of Chelyabinsk Meteoroid

    Science.gov (United States)

    Chernogor, L. F.

    2017-06-01

    Purpose: The parameters of the shock-wave source in the atmosphere and seismic oscillations that this source caused are investigated Design/methodology/approach: The atmospheric and seismic processes caused by the passage and explosion of Chelyabinsk meteoroid on February 15, 2013 have been modelled. The model results are compared with the observation results obtained at several seismic stations. Findings: The shock-wave impact duration is shown to be equal to approximately 97 s, and the time delays of the shockwave at the sites of destruction relative to its generation time at altitudes of 23÷53 km are shown to be equal to 77÷295 s in the distance range interval of 23÷84 km. The length of the area destructed by the shock with the access pressure of no less than 0.7 kPa is determined to be equal to 125÷130 km, and its width to 16÷60 km at various parts of the meteoroid path. The regression relation between the duration of the seismic signal and the length of the seismic wave path has been determined. The characteristic scale time of seismic source impact is equal to approximately 40 s. In the 20÷50 -s period range of seismic oscillations, the dependence of the group speed on period is established. The attenuation depth of seismic waves is estimated to be approximately 10÷20 Mm in the frequency range of 0.25÷3.0 Hz, and the Earth’s crust speed to 5.7÷7.0 μm/s. Conclusions: The model and estimation results are in good agreement with the observations.

  20. Multidimensional seismic data reconstruction using tensor analysis

    Science.gov (United States)

    Kreimer, Nadia

    Exploration seismology utilizes the seismic wavefield for prospecting oil and gas. The seismic reflection experiment consists on deploying sources and receivers in the surface of an area of interest. When the sources are activated, the receivers measure the wavefield that is reflected from different subsurface interfaces and store the information as time-series called traces or seismograms. The seismic data depend on two source coordinates, two receiver coordinates and time (a 5D volume). Obstacles in the field, logistical and economical factors constrain seismic data acquisition. Therefore, the wavefield sampling is incomplete in the four spatial dimensions. Seismic data undergoes different processes. In particular, the reconstruction process is responsible for correcting sampling irregularities of the seismic wavefield. This thesis focuses on the development of new methodologies for the reconstruction of multidimensional seismic data. This thesis examines techniques based on tensor algebra and proposes three methods that exploit the tensor nature of the seismic data. The fully sampled volume is low-rank in the frequency-space domain. The rank increases when we have missing traces and/or noise. The methods proposed perform rank reduction on frequency slices of the 4D spatial volume. The first method employs the Higher-Order Singular Value Decomposition (HOSVD) immersed in an iterative algorithm that reinserts weighted observations. The second method uses a sequential truncated SVD on the unfoldings of the tensor slices (SEQ-SVD). The third method formulates the rank reduction problem as a convex optimization problem. The measure of the rank is replaced by the nuclear norm of the tensor and the alternating direction method of multipliers (ADMM) minimizes the cost function. All three methods have the interesting property that they are robust to curvature of the reflections, unlike many reconstruction methods. Finally, we present a comparison between the methods

  1. Seismic Noise Analysis and Reduction through Utilization of Collocated Seismic and Atmospheric Sensors at the GRO Chile Seismic Network

    Science.gov (United States)

    Farrell, M. E.; Russo, R. M.

    2013-12-01

    The installation of Earthscope Transportable Array-style geophysical observatories in Chile expands open data seismic recording capabilities in the southern hemisphere by nearly 30%, and has nearly tripled the number of seismic stations providing freely-available data in southern South America. Through the use of collocated seismic and atmospheric sensors at these stations we are able to analyze how local atmospheric conditions generate seismic noise, which can degrade data in seismic frequency bands at stations in the ';roaring forties' (S latitudes). Seismic vaults that are climate-controlled and insulated from the local environment are now employed throughout the world in an attempt to isolate seismometers from as many noise sources as possible. However, this is an expensive solution that is neither practical nor possible for all seismic deployments; and also, the increasing number and scope of temporary seismic deployments has resulted in the collection and archiving of terabytes of seismic data that is affected to some degree by natural seismic noise sources such as wind and atmospheric pressure changes. Changing air pressure can result in a depression and subsequent rebound of Earth's surface - which generates low frequency noise in seismic frequency bands - and even moderate winds can apply enough force to ground-coupled structures or to the surface above the seismometers themselves, resulting in significant noise. The 10 stations of the permanent Geophysical Reporting Observatories (GRO Chile), jointly installed during 2011-12 by IRIS and the Chilean Servicio Sismológico, include instrumentation in addition to the standard three seismic components. These stations, spaced approximately 300 km apart along the length of the country, continuously record a variety of atmospheric data including infrasound, air pressure, wind speed, and wind direction. The collocated seismic and atmospheric sensors at each station allow us to analyze both datasets together, to

  2. Factors Affecting Seismic Velocity in Alluvium

    Science.gov (United States)

    Huckins-Gang, H.; Mercadante, J.; Prothro, L.

    2015-12-01

    Yucca Flat at the Nevada National Security Site has been selected as the Source Physics Experiment (SPE) Dry Alluvium Geology Phase II site. The alluvium in this part of Yucca Flat is typical of desert basin fill, with discontinuous beds that are highly variable in clast size and provenance. Detailed understanding of the subsurface geology will be needed for interpretation of the SPE seismic data. A 3D seismic velocity model, created for Yucca Flat using interval seismic velocity data, shows variations in velocity within alluvium near the SPE Phase II site beyond the usual gradual increase of density with depth due to compaction. In this study we examined borehole lithologic logs, geophysical logs, downhole videos, and laboratory analyses of sidewall core samples to understand which characteristics of the alluvium are related to these variations in seismic velocity. Seismic velocity of alluvium is generally related to its density, which can be affected by sediment provenance, clast size, gravel percentage, and matrix properties, in addition to compaction. This study presents a preliminary subdivision of the alluvial strata in the SPE Phase II area into mappable units expected to be significant to seismic modeling. Further refinements of the alluvial units may be possible when seismic data are obtained from SPE Phase II tests. This work was done by National Security Technologies, LLC, under Contract No. DE-AC52-06NA25946 with the U.S. Department of Energy.

  3. Natural fracture characterization using passive seismic illumination

    Energy Technology Data Exchange (ETDEWEB)

    Nihei, K.T.

    2003-01-08

    The presence of natural fractures in reservoir rock can significantly enhance gas production, especially in tight gas formations. Any general knowledge of the existence, location, orientation, spatial density, and connectivity of natural fractures, as well as general reservoir structure, that can be obtained prior to active seismic acquisition and drilling can be exploited to identify key areas for subsequent higher resolution active seismic imaging. Current practices for estimating fracture properties before the acquisition of surface seismic data are usually based on the assumed geology and tectonics of the region, and empirical or fracture mechanics-based relationships between stratigraphic curvature and fracturing. The objective of this research is to investigate the potential of multicomponent surface sensor arrays, and passive seismic sources in the form of local earthquakes to identify and characterize potential fractured gas reservoirs located near seismically active regions. To assess the feasibility of passive seismic fracture detection and characterization, we have developed numerical codes for modeling elastic wave propagation in reservoir structures containing multiple, finite-length fractures. This article describes our efforts to determine the conditions for favorable excitation of fracture converted waves, and to develop an imaging method that can be used to locate and characterize fractures using multicomponent, passive seismic data recorded on a surface array.

  4. Global Seismic Cross-Correlation Results: Characterizing Repeating Seismic Events

    Science.gov (United States)

    Vieceli, R.; Dodge, D. A.; Walter, W. R.

    2016-12-01

    Increases in seismic instrument quality and coverage have led to increased knowledge of earthquakes, but have also revealed the complex and diverse nature of earthquake ruptures. Nonetheless, some earthquakes are sufficiently similar to each other that they produce correlated waveforms. Such repeating events have been used to investigate interplate coupling of subduction zones [e.g. Igarashi, 2010; Yu, 2013], study spatio-temporal changes in slip rate at plate boundaries [e.g. Igarashi et al., 2003], observe variations in seismic wave propagation velocities in the crust [e.g. Schaff and Beroza, 2004; Sawazaki et al., 2015], and assess inner core rotation [e.g. Yu, 2016]. The characterization of repeating events on a global scale remains a very challenging problem. An initial global seismic cross-correlation study used over 310 million waveforms from nearly 3.8 million events recorded between 1970 and 2013 to determine an initial look at global correlated seismicity [Dodge and Walter, 2015]. In this work, we analyze the spatial and temporal distribution of the most highly correlated event clusters or "multiplets" from the Dodge and Walter [2015] study. We examine how the distributions and characteristics of multiplets are effected by tectonic environment, source-station separation, and frequency band. Preliminary results suggest that the distribution of multiplets does not correspond to the tectonic environment in any obvious way, nor do they always coincide with the occurrence of large earthquakes. Future work will focus on clustering correlated pairs and working to reduce the bias introduced by non-uniform seismic station coverage and data availability. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  5. Relative excitation of the seismic shear waves Sn and Lg as a function of source depth and their propagation from Melanesia and Banda arcs to Australia

    Directory of Open Access Journals (Sweden)

    J. OLIVER

    1977-06-01

    Full Text Available SUMMARY. - Seismic activity associated with the collision of the continental
    part of the Australian plate with the oceanic Melanesian arcs along Papua New
    Guinea and the Banda arc provides an unusual opportunity to study the relative
    excitation of the seismic shear waves Sn and Lg. These waves are produced by
    earthquakes located along the arcs in the upper 200 km of the earth and are
    recorded by the Australian WWSSN Stations at Charters Towers (CTA and Alice
    Springs (ASP. The paths to these stations are predominantly continental. The data
    clearly show that for events located at crustal depths, Lg is the predominant phase
    on the records and Sn is either absent or very weak. For events deeper than about
    50-70 km, Sn becomes the predominant phase on the records. These observations
    arc in qualitative agreement with the explanations of Sn and Lg as higher
    modes of surface waves, for the particle displacement amplitudes are maximum
    within the crust for Lg and maximum within the lid of the lithospheric mantle
    for Sn. The data suggest that either the crustal wave guide for Lg is more
    efficient than that for Sn, or that Lg is more easily excited than Sn. No clear
    Lg is observed from shallow earthquakes when the length of the segment of the
    path crossing oceanic structure is greater than about 200 km. Also, widespread
    Quaternary volcanism within the « stable » area of central Papua New Guinea
    to the south of the mobile belt does not seem to affect the efficient transmission
    of high-frequency (1 Hz shear energy.
    The paths from events located along the New Hebrides, Solomon, and New
    Britain arcs to Australia traverse oceanic structure, and no Lg is observed from
    these paths. The inefficient propagation of Sn along these paths from both
    shallow and intermediate-depth events can be explained as follows: 1 For
    the New Hebrides case, the

  6. Crust and upper-mantle structure of Wanganui Basin and southern Hikurangi margin, North Island, New Zealand as revealed by active source seismic data

    Science.gov (United States)

    Tozer, B.; Stern, T. A.; Lamb, S. L.; Henrys, S. A.

    2017-11-01

    Wide-angle reflection and refraction data recorded during the Seismic Array HiKurangi Experiment (SAHKE) are used to constrain the crustal P-wave velocity (Vp) structure along two profiles spanning the length and width of Wanganui Basin, located landwards of the southern Hikurangi subduction margin, New Zealand. These models provide high-resolution constraints on the structure and crustal thickness of the overlying Australian and subducted Pacific plates and plate interface geometry. Wide-angle reflections are modelled to show that the subducted oceanic Pacific plate crust is anomalously thick (∼10 km) below southern North Island and is overlain by a ∼1.5-4.0 km thick, low Vp (4.8-5.4 km s-1) layer, interpreted as a channel of sedimentary material, that persists landwards at least as far as Kapiti Island. Distinct near vertical reflections from onshore shots identify a ∼4 km high mound of low-velocity sedimentary material that appears to underplate the overlying Australian plate crust and is likely to contribute to local rock uplift along the Axial ranges. The overriding Australian plate Moho beneath Wanganui Basin is imaged as deepening southwards and reaches a depth of at least 36.4 km. The Moho shape approximately mirrors the thickening of the basin sediments, suggestive of crustal downwarping. However, the observed crustal thickness variation is insufficient to explain the large negative Bouguer gravity anomaly (-160 mGal) centred over the basin. Partial serpentinization within the upper mantle with a concomitant density decrease is one possible way of reconciling this anomaly.

  7. Crust and upper-mantle structure of Wanganui Basin and southern Hikurangi margin, North Island, New Zealand as revealed by active source seismic data

    Science.gov (United States)

    Tozer, B.; Stern, T. A.; Lamb, S. L.; Henrys, S. A.

    2017-11-01

    Wide-angle reflection and refraction data recorded during the Seismic Array HiKurangi Experiment (SAHKE) are used to constrain the crustal P-wave velocity (Vp) structure along two profiles spanning the length and width of Wanganui Basin, located landwards of the southern Hikurangi subduction margin, New Zealand. These models provide high-resolution constraints on the structure and crustal thickness of the overlying Australian and subducted Pacific plates and plate interface geometry. Wide-angle reflections are modelled to show that the subducted oceanic Pacific plate crust is anomalously thick (˜10 km) below southern North Island and is overlain by a ˜1.5-4.0 km thick, low Vp (4.8-5.4 km s-1) layer, interpreted as a channel of sedimentary material, that persists landwards at least as far as Kapiti Island. Distinct near vertical reflections from onshore shots identify a ˜4 km high mound of low-velocity sedimentary material that appears to underplate the overlying Australian plate crust and is likely to contribute to local rock uplift along the Axial ranges. The overriding Australian plate Moho beneath Wanganui Basin is imaged as deepening southwards and reaches a depth of at least 36.4 km. The Moho shape approximately mirrors the thickening of the basin sediments, suggestive of crustal downwarping. However, the observed crustal thickness variation is insufficient to explain the large negative Bouguer gravity anomaly (-160 mGal) centred over the basin. Partial serpentinization within the upper mantle with a concomitant density decrease is one possible way of reconciling this anomaly.

  8. Use of the t-distribution to construct seismic hazard curves for seismic probabilistic safety assessments

    Energy Technology Data Exchange (ETDEWEB)

    Yee, Eric [KEPCO International Nuclear Graduate School, Dept. of Nuclear Power Plant Engineering, Ulsan (Korea, Republic of)

    2017-03-15

    Seismic probabilistic safety assessments are used to help understand the impact potential seismic events can have on the operation of a nuclear power plant. An important component to seismic probabilistic safety assessment is the seismic hazard curve which shows the frequency of seismic events. However, these hazard curves are estimated assuming a normal distribution of the seismic events. This may not be a strong assumption given the number of recorded events at each source-to-site distance. The use of a normal distribution makes the calculations significantly easier but may underestimate or overestimate the more rare events, which is of concern to nuclear power plants. This paper shows a preliminary exploration into the effect of using a distribution that perhaps more represents the distribution of events, such as the t-distribution to describe data. The integration of a probability distribution with potentially larger tails basically pushes the hazard curves outward, suggesting a different range of frequencies for use in seismic probabilistic safety assessments. Therefore the use of a more realistic distribution results in an increase in the frequency calculations suggesting rare events are less rare than thought in terms of seismic probabilistic safety assessment. However, the opposite was observed with the ground motion prediction equation considered.

  9. Sources

    OpenAIRE

    2014-01-01

    Archives Archivo Histórico del Estado de Jalisco Fondo Gobernación, Asunto Pasaportes y Salvoconductos : G-8-877/9773-9775 G-8-878/9774, 9776, 9777 et 9781 G-8-879/9782-9788 G-8-880/9789-9798 G-8-881-882/9803 G-8-882/9804-9805 G-8-883/9806-9811 G-8-884/9813 G-8-885/9817-9820 G-8-886/9822-9825 G-8-887/9826-9830 G-8-888/9835 G-8-889-890/9837 G-8-889/9839 Sources imprimées Livres et chroniques O’Farrill Romulo, (2004) Reseña histórica estadística y comercial de México y sus estados, directorio g...

  10. Velocity-measurement bias of the ambient noise method due to source directivity: a case study for the Swedish National Seismic Network

    Science.gov (United States)

    Sadeghisorkhani, Hamzeh; Gudmundsson, Ólafur; Roberts, Roland; Tryggvason, Ari

    2017-06-01

    The bias of velocity measurements from ambient-noise covariograms due to an anisotropic distribution of noise sources is studied assuming that the noise field consists of planar surface waves from large distance. First, general characteristics of the bias are described in terms of their dependence on wavelength, source-anomaly amplitude and width. Second, the expected bias of measurements in Sweden based on a noise-source model for the adjacent regions is analysed. The bias is conceptually explained and described in terms of two regimes, namely a high-frequency and a finite-frequency regime and their parameter domains quantified. Basic scaling laws are established for the bias. It is generally found to be small compared to lateral heterogeneity, except in the finite-frequency regime when interstation distance is small compared to a wavelength and in regions of low levels of heterogeneity. The potential bias, that is, its peak-to-peak variation, is generally higher for group-velocity than phase-velocity measurements. The strongly varying noise-source distribution as seen from Sweden results in predictions of relatively strong bias in the area at relevant frequencies and interstation distances. Levels of heterogeneity in the Baltic shield are relatively low, rendering the potential bias significant. This highlights the need for detailed studies of source anisotropy before application of ambient-noise tomography, particularly in regions with weak velocity heterogeneity. Predicted bias only partially explains deviations of phase-velocity measurements from a regional average for individual station pairs. Restricting measurements to station pairs with interstation distance exceeding five wavelengths limits the potential velocity bias in the area to within 1 per cent. This rather dramatic restriction can be relaxed by directional analysis of the noise-source field and application of azimuthal restrictions to the selected station pairs for measurement.

  11. Medium effect on the characteristics of the coupled seismic and electromagnetic signals.

    Science.gov (United States)

    Huang, Qinghua; Ren, Hengxin; Zhang, Dan; Chen, Y John

    2015-01-01

    Recently developed numerical simulation technique can simulate the coupled seismic and electromagnetic signals for a double couple point source or a finite fault planar source. Besides the source effect, the simulation results showed that both medium structure and medium property could affect the coupled seismic and electromagnetic signals. The waveform of coupled signals for a layered structure is more complicated than that for a simple uniform structure. Different from the seismic signals, the electromagnetic signals are sensitive to the medium properties such as fluid salinity and fluid viscosity. Therefore, the co-seismic electromagnetic signals may be more informative than seismic signals.

  12. OPTIMIZATION OF MANUFACTURING TEHNOLOGY FOR “ECCENTRIC MASS” COMPONENT OF A NEW TYPE OF VIBRATORY COMPACTOR USING NX 7.5 SOFTWARE

    Directory of Open Access Journals (Sweden)

    Eftimie Dorin

    2013-11-01

    Full Text Available The paper presents the technological optimization process of the eccentric mass component using the NX 7.5 software. The new design of the vibratory compactor with variable amplitudes was modeled 3D. The manufacturing technology presents graphical aspects of operations during mechanical processing.

  13. Probabilistic seismic hazard assessment for Central Asia

    Directory of Open Access Journals (Sweden)

    Shahid Ullah

    2015-04-01

    Full Text Available Central Asia is one of the seismically most active regions in the world. Its complex seismicity due to the collision of the Eurasian and Indian plates has resulted in some of the world’s largest intra-plate events over history. The region is dominated by reverse faulting over strike slip and normal faulting events. The GSHAP project (1999, aiming at a hazard assessment on a global scale, indicated that the region of Central Asia is characterized by peak ground accelerations for 10% probability of exceedance in 50 years as high as 9 m/s2. In this study, carried out within the framework of the EMCA project (Earthquake Model Central Asia, the area source model and different kernel approaches are used for a probabilistic seismic hazard assessment (PSHA for Central Asia. The seismic hazard is assessed considering shallow (depth < 50 km seismicity only and employs an updated (with respect to previous projects earthquake catalog for the region. The seismic hazard is calculated in terms of macroseismic intensity (MSK-64, intended to be used for the seismic risk maps of the region. The hazard maps, shown in terms of 10% probability of exceedance in 50 years, are derived by using the OpenQuake software [Pagani et al. 2014], which is an open source software tool developed by the GEM (Global Earthquake Model foundation. The maximum hazard observed in the region reaches an intensity of around 8 in southern Tien Shan for 475 years mean return period. The maximum hazard estimated for some of the cities in the region, Bishkek, Dushanbe, Tashkent and Almaty, is between 7 and 8 (7-8, 8.0, 7.0 and 8.0 macroseismic Intensity, respectively, for 475 years mean return period, using different approaches. The results of different methods for assessing the level of seismic hazard are compared and their underlying methodologies are discussed.

  14. The vibrational source strength descriptor using power input from equivalent forces: a simulation study

    DEFF Research Database (Denmark)

    Laugesen, Søren; Ohlrich, Mogens

    1994-01-01

    Simple, yet reliable methods for the approximate determination of the vibratory power supplied by the internal excitation forces of a given vibrational source are of great interest. One such method that relies on the application of a number of “equivalent forces” and measurements of the mean squa...

  15. Effect of geological medium on seismic signals from underground ...

    Indian Academy of Sciences (India)

    media and the high strain rate dependence of the response. However, it is important to establish the effect of local inelastic and nonlinear behaviour of the geological media on the shock waves near the source and the seismic signals beyond the elastic radius. This study would help to esti- mate the limitations of seismic ...

  16. Optimum Geometry For Roll Along In Seismic Refraction ...

    African Journals Online (AJOL)

    Seismic refraction is mostly used in geotechnical work to determine the velocity of the overburden and the refractor velocity. Roll along, in seismic refraction tomography, is important for three reasons. These are to increase the profile length beyond the distance dictated by the source and the instrument (number of receiver ...

  17. The 2016 Kaikōura Earthquake Revealed by Kinematic Source Inversion and Seismic Wavefield Simulations: Slow Rupture Propagation on a Geometrically Complex Crustal Fault Network

    Science.gov (United States)

    Holden, C.; Kaneko, Y.; D'Anastasio, E.; Benites, R.; Fry, B.; Hamling, I. J.

    2017-11-01

    The 2016 Kaikōura (New Zealand) earthquake generated large ground motions and resulted in multiple onshore and offshore fault ruptures, a profusion of triggered landslides, and a regional tsunami. Here we examine the rupture evolution using two kinematic modeling techniques based on analysis of local strong-motion and high-rate GPS data. Our kinematic models capture a complex pattern of slowly (Vr < 2 km/s) propagating rupture from south to north, with over half of the moment release occurring in the northern source region, mostly on the Kekerengu fault, 60 s after the origin time. Both models indicate rupture reactivation on the Kekerengu fault with the time separation of 11 s between the start of the original failure and start of the subsequent one. We further conclude that most near-source waveforms can be explained by slip on the crustal faults, with little (<8%) or no contribution from the subduction interface.

  18. Seismic Imaging and Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Lianjie [Los Alamos National Laboratory

    2012-07-09

    I give an overview of LANL's capability in seismic imaging and monitoring. I present some seismic imaging and monitoring results, including imaging of complex structures, subsalt imaging of Gulf of Mexico, fault/fracture zone imaging for geothermal exploration at the Jemez pueblo, time-lapse imaging of a walkway vertical seismic profiling data for monitoring CO{sub 2} inject at SACROC, and microseismic event locations for monitoring CO{sub 2} injection at Aneth. These examples demonstrate LANL's high-resolution and high-fidelity seismic imaging and monitoring capabilities.

  19. Engineering applications and analysis of vibratory motion fourth order fluid film over the time dependent heated flat plate

    Science.gov (United States)

    Mohmand, Muhammad Ismail; Mamat, Mustafa Bin; Shah, Qayyum

    2017-07-01

    This article deals with the time dependent analysis of thermally conducting and Magneto-hydrodynamic (MHD) liquid film flow of a fourth order fluid past a vertical and vibratory plate. In this article have been developed for higher order complex nature fluids. The governing-equations have been modeled in the terms of nonlinear partial differential equations with the help of physical boundary circumstances. Two different analytical approaches i.e. Adomian decomposition method (ADM) and the optimal homotopy asymptotic method (OHAM), have been used for discoveryof the series clarification of the problems. Solutions obtained via two diversemethods have been compared using the graphs, tables and found an excellent contract. Variants of the embedded flow parameters in the solution have been analysed through the graphical diagrams.

  20. Delineation of seismic source zones based on seismicity parameters ...

    Indian Academy of Sciences (India)

    The spatial variation of rock level peak horizontal acceleration (PHA) and spectral acceleration (Sa) values corresponding to return periods of 475 and 2500 years for the entire study area are presented in this work. The peak ground acceleration (PGA) values at ground surface level were estimated based on different ...

  1. Low-frequency vibratory exercise reduces the risk of bone fracture more than walking: a randomized controlled trial.

    Science.gov (United States)

    Gusi, Narcís; Raimundo, Armando; Leal, Alejo

    2006-11-30

    Whole-body vibration (WBV) is a new type of exercise that has been increasingly tested for the ability to prevent bone fractures and osteoporosis in frail people. There are two currently marketed vibrating plates: a) the whole plate oscillates up and down; b) reciprocating vertical displacements on the left and right side of a fulcrum, increasing the lateral accelerations. A few studies have shown recently the effectiveness of the up-and-down plate for increasing Bone Mineral Density (BMD) and balance; but the effectiveness of the reciprocating plate technique remains mainly unknown. The aim was to compare the effects of WBV using a reciprocating platform at frequencies lower than 20 Hz and a walking-based exercise programme on BMD and balance in post-menopausal women. Twenty-eight physically untrained post-menopausal women were assigned at random to a WBV group or a Walking group. Both experimental programmes consisted of 3 sessions per week for 8 months. Each vibratory session included 6 bouts of 1 min (12.6 Hz in frequency and 3 cm in amplitude with 60 degrees of knee flexion) with 1 min rest between bouts. Each walking session was 55 minutes of walking and 5 minutes of stretching. Hip and lumbar BMD (g.cm-2) were measured using dual-energy X-ray absorptiometry and balance was assessed by the blind flamingo test. ANOVA for repeated measurements was adjusted by baseline data, weight and age. After 8 months, BMD at the femoral neck in the WBV group was increased by 4.3% (P = 0.011) compared to the Walking group. In contrast, the BMD at the lumbar spine was unaltered in both groups. Balance was improved in the WBV group (29%) but not in the Walking group. The 8-month course of vibratory exercise using a reciprocating plate is feasible and is more effective than walking to improve two major determinants of bone fractures: hip BMD and balance.

  2. Seismic Risk Perception compared with seismic Risk Factors

    Science.gov (United States)

    Crescimbene, Massimo; La Longa, Federica; Pessina, Vera; Pino, Nicola Alessandro; Peruzza, Laura

    2016-04-01

    The communication of natural hazards and their consequences is one of the more relevant ethical issues faced by scientists. In the last years, social studies have provided evidence that risk communication is strongly influenced by the risk perception of people. In order to develop effective information and risk communication strategies, the perception of risks and the influencing factors should be known. A theory that offers an integrative approach to understanding and explaining risk perception is still missing. To explain risk perception, it is necessary to consider several perspectives: social, psychological and cultural perspectives and their interactions. This paper presents the results of the CATI survey on seismic risk perception in Italy, conducted by INGV researchers on funding by the DPC. We built a questionnaire to assess seismic risk perception, with a particular attention to compare hazard, vulnerability and exposure perception with the real data of the same factors. The Seismic Risk Perception Questionnaire (SRP-Q) is designed by semantic differential method, using opposite terms on a Likert scale to seven points. The questionnaire allows to obtain the scores of five risk indicators: Hazard, Exposure, Vulnerability, People and Community, Earthquake Phenomenon. The questionnaire was administered by telephone interview (C.A.T.I.) on a statistical sample at national level of over 4,000 people, in the period January -February 2015. Results show that risk perception seems be underestimated for all indicators considered. In particular scores of seismic Vulnerability factor are extremely low compared with house information data of the respondents. Other data collected by the questionnaire regard Earthquake information level, Sources of information, Earthquake occurrence with respect to other natural hazards, participation at risk reduction activities and level of involvement. Research on risk perception aims to aid risk analysis and policy-making by

  3. 100 years of seismic research on the Moho

    DEFF Research Database (Denmark)

    Prodehl, Claus; Kennett, Brian; Artemieva, Irina

    2013-01-01

    , passive seismology using distant earthquakes has played an increasingly important role in studies of crustal structure. The receiver function technique exploiting conversions between P and SV waves at discontinuities in seismic wavespeed below a seismic station has been extensively applied......The detection of a seismic boundary, the “Moho”, between the outermost shell of the Earth, the Earth's crust, and the Earth's mantle by A. Mohorovičić was the consequence of increased insight into the propagation of seismic waves caused by earthquakes. This short history of seismic research...... to the increasing numbers of permanent and portable broad-band seismic stations across the globe. Receiver function studies supplement controlled source work with improved geographic coverage and now make a significant contribution to knowledge of the nature of the crust and the depth to Moho...

  4. Seismic imaging of post glacial sediments - technical problems and solutions

    Science.gov (United States)

    Grzyb, Jaroslaw; Majdański, Mariusz

    2017-04-01

    Near surface seismic imaging of post glacial sediments is difficult, as standard methods hardly works. To recognize such complicated shallow structures it is necessary to acquire a high resolution data, and that leads to several technical problems. In this work we present how we solved the problem of precise time measurements for our seismic source based on GPS system, and how we improved performance of our seismic source. Our solution for timing is based on geodetic instrument and is used with a standard accelerated weith drop (PEG-40) and a sledgehammer, but also with hydrophones in marine environment with chemical sources. This technology has been used in several field experiment of local and regional scale in Central Europe, but also in Arctic. In near future this technology will be used in permafrost study in Spitsbergen, and also with near-surface analysis with three component sources and receivers. We present initial results of our observations of horizontal component seismic source.

  5. Cross-modal effects on learning: a seismic stimulus improves color discrimination learning in a jumping spider.

    Science.gov (United States)

    VanderSal, Nicole D; Hebets, Eileen A

    2007-10-01

    The production of multimodal signals during animal displays is extremely common, and the function of such complex signaling has received much attention. Currently, the most frequently explored hypotheses regarding the evolution and function of complex signaling focus on the signal and/or signaler, or the signaling environment, while much less attention has been placed on the receivers. However, recent studies using vertebrates suggest that receiver psychology (e.g. learning and memory) may play a large role in the evolution of complex signaling. To date, the influence of multimodal cues on receiver learning and/or memory has not been studied in invertebrates. Here, we test the hypothesis that the presence of a seismic (vibratory) stimulus improves color discrimination learning in the jumping spider Habronattus dossenus. Using a heat-aversion learning experiment, we found evidence for a cross-modal effect on color learning. Over a series of training trials, individuals exposed to a seismic stimulus jumped onto the heated color less frequently and remained there for less time than did individuals not exposed to a seismic stimulus. In addition, in a final no-heat test trial, individuals from the seismic-present treatment were more likely to avoid the previously heated color than were individuals from the seismic-absent treatment. This is the first study to demonstrate a cross-modal influence on learning in an invertebrate.

  6. Seismic Catalogue and Seismic Network in Haiti

    Science.gov (United States)

    Belizaire, D.; Benito, B.; Carreño, E.; Meneses, C.; Huerfano, V.; Polanco, E.; McCormack, D.

    2013-05-01

    The destructive earthquake occurred on January 10, 2010 in Haiti, highlighted the lack of preparedness of the country to address seismic phenomena. At the moment of the earthquake, there was no seismic network operating in the country, and only a partial control of the past seismicity was possible, due to the absence of a national catalogue. After the 2010 earthquake, some advances began towards the installation of a national network and the elaboration of a seismic catalogue providing the necessary input for seismic Hazard Studies. This paper presents the state of the works carried out covering both aspects. First, a seismic catalogue has been built, compiling data of historical and instrumental events occurred in the Hispaniola Island and surroundings, in the frame of the SISMO-HAITI project, supported by the Technical University of Madrid (UPM) and Developed in cooperation with the Observatoire National de l'Environnement et de la Vulnérabilité of Haiti (ONEV). Data from different agencies all over the world were gathered, being relevant the role of the Dominican Republic and Puerto Rico seismological services which provides local data of their national networks. Almost 30000 events recorded in the area from 1551 till 2011 were compiled in a first catalogue, among them 7700 events with Mw ranges between 4.0 and 8.3. Since different magnitude scale were given by the different agencies (Ms, mb, MD, ML), this first catalogue was affected by important heterogeneity in the size parameter. Then it was homogenized to moment magnitude Mw using the empirical equations developed by Bonzoni et al (2011) for the eastern Caribbean. At present, this is the most exhaustive catalogue of the country, although it is difficult to assess its degree of completeness. Regarding the seismic network, 3 stations were installed just after the 2010 earthquake by the Canadian Government. The data were sent by telemetry thought the Canadian System CARINA. In 2012, the Spanish IGN together

  7. INFLUENCE OF THE SPATIAL ARRANGEMENT OF SEISMIC DETECTORS ON THE ACCURACY OF EARTHQUAKE HYPOCENTRE DETERMINATION

    Directory of Open Access Journals (Sweden)

    T. G. Aslanov

    2016-01-01

    Full Text Available Objectives. To determine the coordinates of the seismic focus of an earthquake with a minimum margin of error with the use of an optimal selection of seismic sensors. Method. Seismic wave velocity data, relying on the time discrepancies between the registering of seismic waves on the seismic sensor and the defined error in determining the time difference, were used to identify errors in the location of an earthquake's hypocenter depending on the respective positions of three seismic sensors. Discrepancies between data containing an error and those without it used to determine two hypocenters provide information about the hypocenter locating error. An analysis of the influence of the respective arrangements of the seismic sensors and the earthquake epicentre on the accuracy of determination of epicentre coordinates was carried out. Results. It is established that, in order to improve the accuracy of epicenter and hypocenter earthquake coordinate determination, it is preferable to use different combinations of seismic sensors. The present recommendations are based on the desire to reduce errors in determining the earthquake source coordinates. Due to earthquake epicenter distance determination errors found in different seismic sensors both with increasing and decreasing distance, the hypocenter coordinate determining error has been found to depend on the respective arrangement of seismic sensors and on the earthquake source's geographical location. In order to determine the dependence of the source coordinate determining error on the relative position of three seismic sensors, the third seismic sensor was displaced on a horizontal plane at the location centered at the coordinate of the origin. Conclusion. When selecting seismic sensors it is essential that one of them be located perpendicular to the center of the segment formed by the other two seismic sensors. The probability of a multidirectional error of measurement at the moment of arrival of

  8. Imaging Seismic Reflections

    NARCIS (Netherlands)

    op 't Root, T.J.P.M.; Op 't Root, Timotheus Johannes Petrus Maria

    2011-01-01

    The goal of reflection seismic imaging is making images of the Earth subsurface using surface measurements of reflected seismic waves. Besides the position and orientation of subsurface reflecting interfaces it is a challenge to recover the size or amplitude of the discontinuities. We investigate

  9. Development of a wireless seismic array for volcano monitoring

    Science.gov (United States)

    Moure, David; Toma, Daniel; Lázaro, Antoni Manuel; Del Río, Joaquín; Carreras, Normandino; José Blanco, María

    2014-05-01

    Volcano monitoring is mainly based on three sciences: seismology, geodesy and geochemistry. Seismic arrays are used to locate the seismic source, based on analysis of signals recorded by each seismometer. The most important advantages of arrays over classical seismic networks are: painless deployment, no major infrastructures needed, able to provide an approximate location of a signal that is not feasible by a seismic network. In this paper the design of a low-power wireless array is presented. All sensors transmit acquired data to a central node which is capable to calculate the possible location of the seismic source in real-time. The reliability of those locations depends, among other parameters (number of sensors and geometrical distribution), on precision of time synchronization between the nodes. To achieve the necessary precision, the wireless seismic array implements a time synchronization protocol based on the IEEE1588 protocol, which ensures clock synchronization between nodes better than a microsecond, therefore, signal correlation between sensors is achieved correlating the signals from all the sensors. The ultimate challenge would be that the central node receives data from all the seismometers locating the seismic source, only transmitting the result, which dramatically reduces data traffic. Often, active volcano areas are located far from inhabited areas and data transmission options are limited. In situ calculation is crucial in order to reduce data volume transmission generated by the seismic array.

  10. Finite-Difference Modeling of Seismic Wave Scattering in 3D Heterogeneous Media: Generation of Tangential Motion from an Explosion Source

    Science.gov (United States)

    Hirakawa, E. T.; Pitarka, A.; Mellors, R. J.

    2015-12-01

    Evan Hirakawa, Arben Pitarka, and Robert Mellors One challenging task in explosion seismology is development of physical models for explaining the generation of S-waves during underground explosions. Pitarka et al. (2015) used finite difference simulations of SPE-3 (part of Source Physics Experiment, SPE, an ongoing series of underground chemical explosions at the Nevada National Security Site) and found that while a large component of shear motion was generated directly at the source, additional scattering from heterogeneous velocity structure and topography are necessary to better match the data. Large-scale features in the velocity model used in the SPE simulations are well constrained, however, small-scale heterogeneity is poorly constrained. In our study we used a stochastic representation of small-scale variability in order to produce additional high-frequency scattering. Two methods for generating the distributions of random scatterers are tested. The first is done in the spatial domain by essentially smoothing a set of random numbers over an ellipsoidal volume using a Gaussian weighting function. The second method consists of filtering a set of random numbers in the wavenumber domain to obtain a set of heterogeneities with a desired statistical distribution (Frankel and Clayton, 1986). This method is capable of generating distributions with either Gaussian or von Karman autocorrelation functions. The key parameters that affect scattering are the correlation length, the standard deviation of velocity for the heterogeneities, and the Hurst exponent, which is only present in the von Karman media. Overall, we find that shorter correlation lengths as well as higher standard deviations result in increased tangential motion in the frequency band of interest (0 - 10 Hz). This occurs partially through S-wave refraction, but mostly by P-S and Rg-S waves conversions. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore

  11. Ischia Island: Historical Seismicity and Dynamics

    Science.gov (United States)

    Carlino, S.; Cubellis, E.; Iannuzzi, R.; Luongo, G.; Obrizzo, F.

    2003-04-01

    The seismic energy release in volcanic areas is a complex process and the island of Ischia provides a significant scenario of historical seismicity. This is characterized by the occurence of earthquakes with low energy and high intensity. Information on the seismicity of the island spans about eight centuries, starting from 1228. With regard to effects, the most recent earthquake of 1883 is extensively documented both in the literature and unpublished sources. The earthquake caused 2333 deaths and the destruction of the historical and environmental heritage of some areas of the island. The most severe damage occurred in Casamicciola. This event, which was the first great catastrophe after the unification of Italy in the 1860s (Imax = XI degree MCS), represents an important date in the prevention of natural disasters, in that it was after this earthquake that the first Seismic Safety Act in Italy was passed by which lower risk zones were identified for new settlements. Thanks to such detailed analysis, reliable modelling of the seismic source was also obtained. The historical data onwards makes it possible to identify the area of the epicenter of all known earthquakes as the northern slope of Monte Epomeo, while analysis of the effects of earthquakes and the geological structures allows us to evaluate the stress fields that generate the earthquakes. In a volcanic area, interpretation of the mechanisms of release and propagation of seismic energy is made even more complex as the stress field that acts at a regional level is compounded by that generated from migration of magmatic masses towards the surface, as well as the rheologic properties of the rocks dependent on the high geothermic gradient. Such structural and dynamic conditions make the island of Ischia a seismic area of considerable interest. It would appear necessary to evaluate the expected damage caused by a new event linked to the renewal of dynamics of the island, where high population density and the

  12. Seismic hazard studies in Egypt

    Directory of Open Access Journals (Sweden)

    Abuo El-Ela A. Mohamed

    2012-12-01

    Full Text Available The study of earthquake activity and seismic hazard assessment of Egypt is very important due to the great and rapid spreading of large investments in national projects, especially the nuclear power plant that will be held in the northern part of Egypt. Although Egypt is characterized by low seismicity, it has experienced occurring of damaging earthquake effect through its history. The seismotectonic sitting of Egypt suggests that large earthquakes are possible particularly along the Gulf of Aqaba–Dead Sea transform, the Subduction zone along the Hellenic and Cyprean Arcs, and the Northern Red Sea triple junction point. In addition some inland significant sources at Aswan, Dahshour, and Cairo-Suez District should be considered. The seismic hazard for Egypt is calculated utilizing a probabilistic approach (for a grid of 0.5° × 0.5° within a logic-tree framework. Alternative seismogenic models and ground motion scaling relationships are selected to account for the epistemic uncertainty. Seismic hazard values on rock were calculated to create contour maps for four ground motion spectral periods and for different return periods. In addition, the uniform hazard spectra for rock sites for different 25 periods, and the probabilistic hazard curves for Cairo, and Alexandria cities are graphed. The peak ground acceleration (PGA values were found close to the Gulf of Aqaba and it was about 220 gal for 475 year return period. While the lowest (PGA values were detected in the western part of the western desert and it is less than 25 gal.

  13. A study on seismicity and seismic hazard for Karnataka State

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 121; Issue 2. A study on seismicity and seismic hazard for Karnataka State. T G Sitharam Naveen ... This paper presents a detailed study on the seismic pattern of the state of Karnataka and also quantifies the seismic hazard for the entire state. In the present work, ...

  14. Passive seismic interferometry for reflection imaging & monitoring

    NARCIS (Netherlands)

    Almagro Vidal, C.

    2017-01-01

    Passive seismics is the set of applications that endeavours the exploration of the
    Earth’s mechanical properties using naturally occurring sources in the subsurface.
    Conventional imaging of the subsurface is achieved with the aid of reflection
    surveys of body waves from the surface.

  15. Reflection-response retrieval with seismic interferometry by multidimensional deconvolution from surface reflection data

    NARCIS (Netherlands)

    Boullenger, B.; Hunziker, J.W.; Draganov, D.S.

    2015-01-01

    Seismic interferometry (SI) allows retrieval of virtual-source responses at positions of receivers, where no actual source is shot, by cross-correlating (CC) the seismic responses between receivers. The theory requires a boundary of subsurface sources to retrieve the surface reflection response.

  16. Shear wave seismic interferometry for lithospheric imaging : Application to southern Mexico

    NARCIS (Netherlands)

    Frank, J. G.; Ruigrok, E. N.; Wapenaar, K.

    Seismic interferometry allows for the creation of new seismic traces by cross correlating existing ones. With sufficient sampling of remote-source positions, it is possible to create a virtual source record by transforming a receiver location into a virtual source. The imaging technique developed

  17. Shear wave seismic interferometry for lithospheric imaging : Application to southern Mexico

    NARCIS (Netherlands)

    Frank, J.G.; Ruigrok, E.N.; Wapenaar, C.P.A.

    2014-01-01

    Seismic interferometry allows for the creation of new seismic traces by cross correlating existing ones. With sufficient sampling of remote-source positions, it is possible to create a virtual source record by transforming a receiver location into a virtual source. The imaging technique developed

  18. Body-wave seismic interferometry applied to earthquake- and storm-induced wavefield

    NARCIS (Netherlands)

    Ruigrok, E.N.

    2012-01-01

    Seismology is the study of the vibration of the Earth. Seismologists pay much attention to the main source of Earth vibration: earthquakes. But also other seismic sources, like mining blasts, ocean storms and windmills, are studied. All these sources induce seismic waves, which can eventually be

  19. Source term evaluation for postulated UF{sub 6} release accidents in gaseous diffusion plants -- Summer ventilation mode (non-seismic cases)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.H.; Chen, N.C.J.; Taleyarkhan, R.P.; Wendel, M.W.; Keith, K.D.; Schmidt, R.W. [Oak Ridge National Lab., TN (United States); Carter, J.C. [J.C. Carter Associates, Inc., Knoxville, TN (United States); Dyer, R.H. [Dyer Enterprises, Harriman, TN (United States)

    1996-12-30

    Computer models have been developed to simulate the transient behavior of aerosols and vapors as a result of a postulated accident involving the release of uranium hexafluoride (UF{sub 6}) into the process building of a gaseous diffusion plant. For the current study, gaseous UF{sub 6} is assumed to get released in the cell housing atmosphere through B-line break at 58.97 kg/s for 10 min and 30 min duration at the Paducah and Portsmouth Gaseous Diffusion Plants. The released UF{sub 6} undergoes an exothermic chemical reaction with moisture (H{sub 2}O) in the air to form hydrogen fluoride (HF) and radioactive uranyl fluoride (UO{sub 2}F{sub 2}) while it disperses throughout the process building. As part of a facility-wide safety evaluation, this study evaluated source terms consisting of UO{sub 2}F{sub 2} as well as HF during a postulated UF{sub 6} release accident in a process building. UO{sub 2}F{sub 2} mainly remains as airborne-solid particles (aerosols), and HF is in a vapor form. Some UO{sub 2}F{sub 2} aerosols are removed from the air flow due to gravitational settling. The HF and the remaining UO{sub 2}F{sub 2} are mixed with air and exhausted through the building ventilation system. The MELCOR computer code was selected for simulating aerosols and vapor transport in the process building. To characterize leakage flow through the cell housing wall, 3-D CFD tool (CFDS-FLOW3D) was used. About 57% of UO{sub 2}F{sub 2} was predicted to be released into the environment. Since HF was treated as vapor, close to 100% was estimated to get released into the environment.

  20. Time dependent seismic hazard

    Science.gov (United States)

    Polidoro, B.; Iervolino, I.; Chioccarelli, E.; Giorgio, M.

    2012-04-01

    Probabilistic seismic hazard is usually computed trough a homogeneous Poisson process that even though it is a time-independent process it is widely used for its very convenient properties. However, when a single fault is of concern and/or the time scale is different from that of the long term, time-dependent processes are required. In this paper, different time-dependent models are reviewed with working examples. In fact, the Paganica fault (in central Italy) has been considered to compute both the probability of occurrence of at least one event in the lifespan of the structure, as well as the seismic hazard expressed in terms of probability of exceedance of an intensity value in a given time frame causing the collapse of the structure. Several models, well known or novel application to engineering hazard have been considered, limitation and issues in their applications are also discussed. The Brownian Passage Time (BPT) model is based on a stochastic modification of the deterministic stick-slip oscillator model for characteristic earthquakes; i.e., based on the addition of random perturbations (a Gaussian white noise) to the deterministic load path predicted by elastic rebound theory. This model assumes that the load state is at some ground level immediately after an event, increases steadly over time, reaches a failure threshold and relaxes instantaneously back to the ground level. For this model also a variable threshold has been considered to take into account the uncertainty of the threshold value. For the slip-predictable model it is assumed that the stress accumulates at a constant rate starting from some initial stress level. Stress is assumed to accumulate for a random period of time until an earthquake occurs. The size of the earthquake is governed by the stress release and it is a function of the elapsed time since the last event. In the time-predictable model stress buildup occurs at a constant rate until the accumulated stress reaches a threshold

  1. New comprehensive standard seismic noise models and 3D seismic noise variation for Morocco territory, North Africa, obtained using seismic broadband stations

    Science.gov (United States)

    El Fellah, Younes; El-Aal, Abd El-Aziz Khairy Abd; Harnafi, Mimoun; Villaseñor, Antonio

    2017-05-01

    In the current work, we constructed new comprehensive standard seismic noise models and 3D temporal-spatial seismic noise level cubes for Morocco in north-west Africa to be used for seismological and engineering purposes. Indeed, the original global standard seismic noise models published by Peterson (1993) and their following updates by Astiz and Creager (1995), Ekström (2001) and Berger et al. (2003) had no contributing seismic stations deployed in North Africa. Consequently, this preliminary study was conducted to shed light on seismic noise levels specific to north-west Africa. For this purpose, 23 broadband seismic stations recently installed in different structural domains throughout Morocco are used to study the nature and characteristics of seismic noise and to create seismic noise models for Morocco. Continuous data recorded during 2009, 2010 and 2011 were processed and analysed to construct these new noise models and 3D noise levels from all stations. We compared the Peterson new high-noise model (NHNM) and low-noise model (NLNM) with the Moroccan high-noise model (MHNM) and low-noise model (MLNM). These new noise models are comparable to the United States Geological Survey (USGS) models in the short period band; however, in the period range 1.2 s to 1000 s for MLNM and 10 s to 1000 s for MHNM display significant variations. This variation is attributed to differences in the nature of seismic noise sources that dominate Morocco in these period bands. The results of this study have a new perception about permanent seismic noise models for this spectacular region and can be considered a significant contribution because it supplements the Peterson models and can also be used to site future permanent seismic stations in Morocco.

  2. Seismic Barrier Protection of Critical Infrastructure

    Science.gov (United States)

    Haupt, R.; Liberman, V.; Rothschild, M.

    2016-12-01

    Each year, on average a major magnitude-8 earthquake strikes somewhere in the world. In addition, 10,000 earthquake related deaths occur annually, where collapsing buildings claim by far most lives. Moreover, in recent events, industry activity of oil extraction and wastewater reinjection are suspect to cause earthquake swarms that threaten high-value oil pipeline networks, U.S. oil storage reserves, and civilian homes. Earthquake engineering building structural designs and materials have evolved over many years to minimize the destructive effects of seismic surface waves. However, even under the best engineering practices, significant damage and numbers of fatalities can still occur. In this effort, we present a concept and approach to redirect and attenuate the ground motion amplitudes of earthquake surface waves by implementing an engineered subsurface seismic barrier. The barrier is comprised of a borehole array complex that impedes and diverts destructive surface waves (typically 2-10 km wavelengths). Computational 2D and 3D seismic wave propagation models developed at MIT Lincoln Laboratory suggest that the borehole array arrangement is critical to the redirection and self-interference reduction of broadband hazardous seismic waves in the vicinity of the structure to protect. For validity, the computational models are compared with data obtained from large bench-scale physical models that contain scaled borehole arrays and trenches. Small contact shakers generate elastic waves in solid media, while contact tri-axial accelerometer arrays measure the resultant wave fields. Field tests are presently being conducted to examine the seismic power reduction across a subsurface borehole array generated by controlled, far-field seismic sources. The sources include a weight drop and oriented seismic vibrational sources that generate low frequency surface and body waves. The pre-borehole condition at the site is measured first with a tri-axial geophone arrangement. The

  3. Influence оf 2d Vibratory Motion Conveyed to Billet on Force And Timing Parameters of its Contact Interaction With Sawing Disc

    Directory of Open Access Journals (Sweden)

    M. G. Kiselev

    2014-01-01

    Full Text Available The paper presents an experimental investigation on influence of 2D vibratory dimension conveyed to a billet on force and timing parameters of its contact interaction with a sawing disc. Description of the modernized sawing section ensuring conveyance of 2D vibratory motion to a billet, methodology and  hardware facilities applied for normal force measurement of its impact with the disc and longevity of their contact for the period of the billet circulation motion. The paper provides, analyzes and generalizes experimentally obtained dependences reflecting influence of gap clearance between a boom and an upper stop on the mentioned force and timing parameters of the billet contact interaction with the sawing disc.

  4. Differences in joint-position sense and vibratory threshold in runners with and without a history of overuse injury.

    Science.gov (United States)

    Switlick, Tiffany; Kernozek, Thomas W; Meardon, Stacey

    2015-02-01

    A relationship between altered postural control and injury has been reported in sports. Sensorimotor function serves a fundamental role in postural control and is not often studied in runners. Persons who sustain running injury may have altered sensorimotor function contributing to risk of injury or reinjury. To determine if differences in knee and ankle proprioception or plantar sensation exist between injured and noninjured runners. Retrospective case-control study. University campus. Twenty runners with a history of lower-extremity overuse injury and 20 noninjured runners were examined. Injured runners were subcategorized into 2 groups based on site of injury: foot/ankle and knee/hip. Active absolute joint-repositioning error of the ankle at 20° inversion and 10° eversion and the knee at 15° and 40° flexion was assessed using an isokinetic dynamometer. Vibratory threshold at the calcaneus, arch, and great toe was determined for each subject using a handheld electric sensory threshold instrument. Runners in the injured-foot/ankle group had increased absolute error during ankle-eversion repositioning (6.55° ± 3.58°) compared with those in the noninjured (4.04° ± 1.78°, P = .01) and the hip/knee (3.63° ± 2.2°, P = .01) groups. Runners in the injured group, as a whole, had greater sensitivity in the arch of the plantar surface (2.94 ± 0.52 V) than noninjured runners (2.38 ± 0.53 V, P = .02). Differences in ankle-eversion proprioception between runners with a history of ankle and foot injuries and noninjured runners were observed. Runners with a history of injury also displayed an increased vibratory threshold in the arch region compared with noninjured runners. Poor ankle-joint-position sense and increased plantar sensitivity suggest altered sensorimotor function after injury. These factors may influence underlying postural control and contribute to altered loading responses commonly observed in injured runners.

  5. Low-frequency vibratory exercise reduces the risk of bone fracture more than walking: a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Leal Alejo

    2006-11-01

    Full Text Available Abstract Background Whole-body vibration (WBV is a new type of exercise that has been increasingly tested for the ability to prevent bone fractures and osteoporosis in frail people. There are two currently marketed vibrating plates: a the whole plate oscillates up and down; b reciprocating vertical displacements on the left and right side of a fulcrum, increasing the lateral accelerations. A few studies have shown recently the effectiveness of the up-and-down plate for increasing Bone Mineral Density (BMD and balance; but the effectiveness of the reciprocating plate technique remains mainly unknown. The aim was to compare the effects of WBV using a reciprocating platform at frequencies lower than 20 Hz and a walking-based exercise programme on BMD and balance in post-menopausal women. Methods Twenty-eight physically untrained post-menopausal women were assigned at random to a WBV group or a Walking group. Both experimental programmes consisted of 3 sessions per week for 8 months. Each vibratory session included 6 bouts of 1 min (12.6 Hz in frequency and 3 cm in amplitude with 60° of knee flexion with 1 min rest between bouts. Each walking session was 55 minutes of walking and 5 minutes of stretching. Hip and lumbar BMD (g·cm-2 were measured using dual-energy X-ray absorptiometry and balance was assessed by the blind flamingo test. ANOVA for repeated measurements was adjusted by baseline data, weight and age. Results After 8 months, BMD at the femoral neck in the WBV group was increased by 4.3% (P = 0.011 compared to the Walking group. In contrast, the BMD at the lumbar spine was unaltered in both groups. Balance was improved in the WBV group (29% but not in the Walking group. Conclusion The 8-month course of vibratory exercise using a reciprocating plate is feasible and is more effective than walking to improve two major determinants of bone fractures: hip BMD and balance.

  6. Influence of the Radial Clearance of a Squeeze Film Damper on the Vibratory Behavior of a Single Spool Gas Turbine Designed for Unmanned Aerial Vehicle Applications

    OpenAIRE

    Geraldo Creci; José Orlando Balastrero; Sidney Domingues; Luis Vanderlei Torres; João Carlos Menezes

    2017-01-01

    This study presents a numerical investigation using the finite element method on the vibratory behavior of a single spool gas turbine designed for unmanned aerial vehicle applications. The shaft of the rotor-bearing system is supported on a front bearing composed of a deep groove ball bearing with a vibration absorber element and a rear squeeze film damper bearing. Three radial clearances for the squeeze film damper were analyzed to determine the best geometric configuration for the rear bear...

  7. Seismic Imaging of Open Subsurface Fractures

    Science.gov (United States)

    Myers, S. C.; Pitarka, A.; Matzel, E.; Aguiar, A. C.

    2015-12-01

    Injection of high-pressure fluid into the subsurface is proven to stimulate geothermal, oil, and gas production by opening cracks that increase permeability. The effectiveness of increasing permeability by high-pressure injection has been revolutionized by the introduction of "proppants" into the injected fluid to keep cracks open after the pressure of the stimulation activity ends. The network of fractures produced during stimulation is most commonly inferred by the location of micro-earthquakes. However, existing (closed) fractures may open aseismically, so the whole fracture network may not be imaged by micro-seismic locations alone. Further, whether all new fractures remain open and for how long remains unclear. Open cracks, even fluid-filled cracks, scatter seismic waves because traction forces are not transmitted across the gap. Numerical simulation confirms that an open crack with dimensions on the order of 10 meters can scatter enough seismic energy to change the coda of seismic signals. Our simulations show that changes in seismic coda due to newly opened fractures are only a few percent of peak seismogram amplitudes, making signals from open cracks difficult to identify. We are developing advanced signal processing methods to identify candidate signals that originate from open cracks. These methods are based on differencing seismograms that are recorded before and after high-pressure fluid injection events to identify changes in the coda. The origins of candidate signals are located using time-reversal techniques to determine if the signals are indeed associated with a coherent structure. The source of scattered energy is compared to micro-seismic event locations to determine whether cracks opened seismically or aseismically. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-675612.

  8. SEISMIC ISOLATION OF NUCLEAR POWER PLANTS

    Directory of Open Access Journals (Sweden)

    ANDREW S. WHITTAKER

    2014-10-01

    The funding by the United States Nuclear Regulatory Commission of a research project to the Lawrence Berkeley National Laboratory and MCEER/University at Buffalo facilitated the writing of a soon-to-be-published NUREG on seismic isolation. Funding of MCEER by the National Science Foundation led to research products that provide the technical basis for a new section in ASCE Standard 4 on the seismic isolation of safety-related nuclear facilities. The performance expectations identified in the NUREG and ASCE 4 for seismic isolation systems, and superstructures and substructures are described in the paper. Robust numerical models capable of capturing isolator behaviors under extreme loadings, which have been verified and validated following ASME protocols, and implemented in the open source code OpenSees, are introduced.

  9. SEISMIC MODELING ENGINES PHASE 1 FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    BRUCE P. MARION

    2006-02-09

    Seismic modeling is a core component of petroleum exploration and production today. Potential applications include modeling the influence of dip on anisotropic migration; source/receiver placement in deviated-well three-dimensional surveys for vertical seismic profiling (VSP); and the generation of realistic data sets for testing contractor-supplied migration algorithms or for interpreting AVO (amplitude variation with offset) responses. This project was designed to extend the use of a finite-difference modeling package, developed at Lawrence Berkeley Laboratories, to the advanced applications needed by industry. The approach included a realistic, easy-to-use 2-D modeling package for the desktop of the practicing geophysicist. The feasibility of providing a wide-ranging set of seismic modeling engines was fully demonstrated in Phase I. The technical focus was on adding variable gridding in both the horizontal and vertical directions, incorporating attenuation, improving absorbing boundary conditions and adding the optional coefficient finite difference methods.

  10. Seismically observed seiching in the Panama Canal

    Science.gov (United States)

    McNamara, D.E.; Ringler, A.T.; Hutt, C.R.; Gee, L.S.

    2011-01-01

    A large portion of the seismic noise spectrum is dominated by water wave energy coupled into the solid Earth. Distinct mechanisms of water wave induced ground motions are distinguished by their spectral content. For example, cultural noise is generally Panama Canal there is an additional source of long-period noise generated by standing water waves, seiches, induced by disturbances such as passing ships and wind pressure. We compare seismic waveforms to water level records and relate these observations to changes in local tilt and gravity due to an oscillating seiche. The methods and observations discussed in this paper provide a first step toward quantifying the impact of water inundation as recorded by seismometers. This type of quantified understanding of water inundation will help in future estimates of similar phenomena such as the seismic observations of tsunami impact. Copyright 2011 by the American Geophysical Union.

  11. BUILDING 341 Seismic Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Halle, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-06-15

    The Seismic Evaluation of Building 341 located at Lawrence Livermore National Laboratory in Livermore, California has been completed. The subject building consists of a main building, Increment 1, and two smaller additions; Increments 2 and 3.

  12. Seismic Creep, USA Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seismic creep is the constant or periodic movement on a fault as contrasted with the sudden rupture associated with an earthquake. It is a usually slow deformation...

  13. Lunar seismic profiling experiment natural activity study

    Science.gov (United States)

    Duennebier, F. K.

    1976-01-01

    The Lunar Seismic Experiment Natural Activity Study has provided a unique opportunity to study the high frequency (4-20 Hz) portion to the seismic spectrum on the moon. The data obtained from the LSPE was studied to evaluate the origin and importance of the process that generates thermal moonquakes and the characteristics of the seismic scattering zone at the lunar surface. The detection of thermal moonquakes by the LSPE array made it possible to locate the sources of many events and determine that they are definitely not generated by astronaut activities but are the result of a natural process on the moon. The propagation of seismic waves in the near-surface layers was studied in a qualitative manner. In the absence of an adequate theoretical model for the propagation of seismic waves in the moon, it is not possible to assign a depth for the scattering layer. The LSPE data does define several parameters which must be satisfied by any model developed in the future.

  14. Salvo: Seismic imaging software for complex geologies

    Energy Technology Data Exchange (ETDEWEB)

    OBER,CURTIS C.; GJERTSEN,ROB; WOMBLE,DAVID E.

    2000-03-01

    This report describes Salvo, a three-dimensional seismic-imaging software for complex geologies. Regions of complex geology, such as overthrusts and salt structures, can cause difficulties for many seismic-imaging algorithms used in production today. The paraxial wave equation and finite-difference methods used within Salvo can produce high-quality seismic images in these difficult regions. However this approach comes with higher computational costs which have been too expensive for standard production. Salvo uses improved numerical algorithms and methods, along with parallel computing, to produce high-quality images and to reduce the computational and the data input/output (I/O) costs. This report documents the numerical algorithms implemented for the paraxial wave equation, including absorbing boundary conditions, phase corrections, imaging conditions, phase encoding, and reduced-source migration. This report also describes I/O algorithms for large seismic data sets and images and parallelization methods used to obtain high efficiencies for both the computations and the I/O of seismic data sets. Finally, this report describes the required steps to compile, port and optimize the Salvo software, and describes the validation data sets used to help verify a working copy of Salvo.

  15. Enhanced sources of acoustic power surrounding AR11429

    OpenAIRE

    Donea, Alina; Hanson, Christopher

    2013-01-01

    Multi-frequency power maps of the local acoustic oscillations show acoustic enhancements (\\acoustic-power halos") at high frequencies surrounding large active region. Computational seismic holography reveals a high-frequency \\acoustic-emission halo", or \\seismic glory" surrounding large active regions. In this study, we have applied computational seismic holography to map the seismic seismic source density surrounding AR 11429. Studies of HMI/SDO Doppler data, shows that the "acoustic halos" ...

  16. Deterministic seismic hazard macrozonation of India

    Science.gov (United States)

    Kolathayar, Sreevalsa; Sitharam, T. G.; Vipin, K. S.

    2012-10-01

    Earthquakes are known to have occurred in Indian subcontinent from ancient times. This paper presents the results of seismic hazard analysis of India (6°-38°N and 68°-98°E) based on the deterministic approach using latest seismicity data (up to 2010). The hazard analysis was done using two different source models (linear sources and point sources) and 12 well recognized attenuation relations considering varied tectonic provinces in the region. The earthquake data obtained from different sources were homogenized and declustered and a total of 27,146 earthquakes of moment magnitude 4 and above were listed in the study area. The sesismotectonic map of the study area was prepared by considering the faults, lineaments and the shear zones which are associated with earthquakes of magnitude 4 and above. A new program was developed in MATLAB for smoothing of the point sources. For assessing the seismic hazard, the study area was divided into small grids of size 0.1° × 0.1° (approximately 10 × 10 km), and the hazard parameters were calculated at the center of each of these grid cells by considering all the seismic sources within a radius of 300 to 400 km. Rock level peak horizontal acceleration (PHA) and spectral accelerations for periods 0.1 and 1 s have been calculated for all the grid points with a deterministic approach using a code written in MATLAB. Epistemic uncertainty in hazard definition has been tackled within a logic-tree framework considering two types of sources and three attenuation models for each grid point. The hazard evaluation without logic tree approach also has been done for comparison of the results. The contour maps showing the spatial variation of hazard values are presented in the paper.

  17. Seismic Hazard analysis of Adjaria Region in Georgia

    Science.gov (United States)

    Jorjiashvili, Nato; Elashvili, Mikheil

    2014-05-01

    The most commonly used approach to determining seismic-design loads for engineering projects is probabilistic seismic-hazard analysis (PSHA). The primary output from a PSHA is a hazard curve showing the variation of a selected ground-motion parameter, such as peak ground acceleration (PGA) or spectral acceleration (SA), against the annual frequency of exceedance (or its reciprocal, return period). The design value is the ground-motion level that corresponds to a preselected design return period. For many engineering projects, such as standard buildings and typical bridges, the seismic loading is taken from the appropriate seismic-design code, the basis of which is usually a PSHA. For more important engineering projects— where the consequences of failure are more serious, such as dams and chemical plants—it is more usual to obtain the seismic-design loads from a site-specific PSHA, in general, using much longer return periods than those governing code based design. Calculation of Probabilistic Seismic Hazard was performed using Software CRISIS2007 by Ordaz, M., Aguilar, A., and Arboleda, J., Instituto de Ingeniería, UNAM, Mexico. CRISIS implements a classical probabilistic seismic hazard methodology where seismic sources can be modelled as points, lines and areas. In the case of area sources, the software offers an integration procedure that takes advantage of a triangulation algorithm used for seismic source discretization. This solution improves calculation efficiency while maintaining a reliable description of source geometry and seismicity. Additionally, supplementary filters (e.g. fix a sitesource distance that excludes from calculation sources at great distance) allow the program to balance precision and efficiency during hazard calculation. Earthquake temporal occurrence is assumed to follow a Poisson process, and the code facilitates two types of MFDs: a truncated exponential Gutenberg-Richter [1944] magnitude distribution and a characteristic magnitude

  18. Joint position sense and vibratory perception sense in patients with Ehlers-Danlos syndrome type III (hypermobility type).

    Science.gov (United States)

    Rombaut, Lies; De Paepe, Anne; Malfait, Fransiska; Cools, Ann; Calders, Patrick

    2010-03-01

    Neurophysiological deficits could make patients with Ehlers-Danlos syndrome (EDS) type III (hypermobility type) more vulnerable to musculoskeletal problems, particularly to joint instability. The purpose of this study was to investigate whether joint position sense (JPS) and vibratory perception sense (VPS) in EDS type III patients in the knee and shoulder joints are impaired. Thirty-two female EDS type III patients as defined by the Villefranche criteria and 32 individually gender- and age-matched healthy control subjects were included in the study. Range of motion was determined using a goniometer, passive and active JPS were assessed with an isokinetic dynamometer system, and the VPS was measured by a biothesiometer. Daily physical activity was evaluated by the Baecke questionnaire. The EDS type III group showed significantly larger ranges of movement (P physical activity (SPA) compared to the control group (P = 0.023). Considering SPA as covariate, the EDS type III group demonstrated a significant impairment in knee joint reposition compared to the control group (P = 0.018). No significant differences were found for shoulder JPS. The VPS was not significantly different in the EDS type III group compared to the control group. In addition, no significant correlation was found between JPS and VPS, neither at the knee nor at the shoulder joint. This is the first study examining proprioception deficits in EDS type III patients as defined by the Villefranche criteria. Further research on the neurophysiological dysfunctions and mechanisms in this pathologic entity is needed.

  19. Design and Analysis of a Novel Fully Decoupled Tri-axis Linear Vibratory Gyroscope with Matched Modes.

    Science.gov (United States)

    Xia, Dunzhu; Kong, Lun; Gao, Haiyu

    2015-07-13

    We present in this paper a novel fully decoupled silicon micromachined tri-axis linear vibratory gyroscope. The proposed gyroscope structure is highly symmetrical and can be limited to an area of about 8.5 mm × 8.5 mm. It can differentially detect three axes' angular velocities at the same time. By elaborately arranging different beams, anchors and sensing frames, the drive and sense modes are fully decoupled from each other. Moreover, the quadrature error correction and frequency tuning functions are taken into consideration in the structure design for all the sense modes. Since there exists an unwanted in-plane rotational mode, theoretical analysis is implemented to eliminate it. To accelerate the mode matching process, the particle swam optimization (PSO) algorithm is adopted and a frequency split of 149 Hz is first achieved by this method. Then, after two steps of manual adjustment of the springs' dimensions, the frequency gap is further decreased to 3 Hz. With the help of the finite element method (FEM) software ANSYS, the natural frequencies of drive, yaw, and pitch/roll modes are found to be 14,017 Hz, 14,018 Hz and 14,020 Hz, respectively. The cross-axis effect and scale factor of each mode are also simulated. All the simulation results are in good accordance with the theoretical analysis, which means the design is effective and worthy of further investigation on the integration of tri-axis accelerometers on the same single chip to form an inertial measurement unit.

  20. Experimental Investigation on the Fatigue Life of Ti-6Al-4V Treated by Vibratory Stress Relief

    Directory of Open Access Journals (Sweden)

    Han-Jun Gao

    2017-05-01

    Full Text Available Vibratory stress relief (VSR is a highly efficient and low-energy consumption method to relieve and homogenize residual stresses in materials. Thus, the effect of VSR on the fatigue life should be determined. Standard fatigue specimens are fabricated to investigate the fatigue life of Ti-6Al-4V titanium alloy treated by VSR. The dynamic stresses generated under different VSR amplitudes are measured, and then the relationship between the dynamic stress and vibration amplitude is obtained. Different specimen groups are subjected to VSRs with different amplitudes and annealing treatment with typical process parameters. Residual stresses are measured to evaluate the stress relieving effects. Finally, the fatigue behavior under different states is determined by uniaxial tension–compression fatigue experiments. Results show that VSR and annealing treatment have negative effects on the fatigue life of Ti-6Al-4V. The fatigue life is decreased with the increase in VSR amplitude. When the VSR amplitude is less than 0.1 mm, the decrease in fatigue limit is less than 2%. Compared with specimens without VSR or annealing treatment, the fatigue limit of the specimens treated by VSR with 0.2 mm amplitude and annealing treatment decreases by 10.60% and 8.52%, respectively. Although the stress relieving effect is better, high amplitude VSR will lead to the decrease of Ti-6Al-4V fatigue life due to the defects generated during vibration. Low amplitude VSR can effectively relieve the stress with little decrease in fatigue life.

  1. Anesthetic block of the dorsal penile nerve inhibits vibratory-induced ejaculation in men with spinal cord injuries.

    Science.gov (United States)

    Wieder, J A; Brackett, N L; Lynne, C M; Green, J T; Aballa, T C

    2000-06-01

    [corrected] We investigated which nerve pathways are necessary to achieve ejaculation using penile vibratory stimulation (PVS) in men with spinal cord injury (SCI). Eight men with SCI were selected based on the presence of a bulbocavernosus reflex (BCR) and consistent antegrade ejaculation with PVS. Level of injury was cervical (4), upper thoracic (4), and lower thoracic (1). Mean age was 30.4 years (range 22 to 38). Usual responses to PVS included autonomic dysreflexia (4), erection (4), and consistent somatic responses such as abdominal contractions (8). Local anesthesia of the dorsal penile nerves (penile block) was achieved using 1% plain lidocaine injection. Effective penile block was confirmed by loss of the BCR. Two PVS ejaculation trials were performed: one trial during the penile block and one trial when the penile block had worn off. In 4 subjects, the bladder contents were analyzed for retrograde ejaculation. With the penile block, ejaculation was inhibited in 100% of the subjects. None of the bladder washings demonstrated sperm, indicating absence of retrograde ejaculation. None of the subjects exhibited their usual erectile response, somatic responses, or signs of autonomic dysreflexia. After the penile block wore off, PVS induced ejaculation in all subjects. If subjects usually had erection, somatic responses, or signs of autonomic dysreflexia, these also returned. Our data suggest that ejaculatory response to PVS in SCI men requires the presence of intact dorsal penile nerves.

  2. Evaluation of seismic reflector slopes with a Yoyo-CTD

    Science.gov (United States)

    Krahmann, G.; Papenberg, C.; Brandt, P.; Vogt, M.

    2009-08-01

    In spring 2007 a dedicated seismic and oceanographic experiment was conducted in the Gulf of Cadiz. Employing two research vessels seismic and hydrographic observations were made contemporaneously and in close proximity. At a 12 hour long station inside a Meddy a conductivity-temperature-depth (CTD) probe was lowered and raised repeatedly while the seismic vessel conducted a repetitive survey on tracks nearby. Over the period 17 CTD profiles were collected covering the depth interval from 500 to 1700 m. The CTD data show the Meddy's elevated temperatures and salinities as well as varying intrusive features. When converted into reflection coefficients and convoluted with the seismic source signal the CTD data agrees well with nearby seismic data. The comparison of the temporal/spatial slopes of CTD-derived reflectors with those of isopycnals shows a good agreement when the slopes are determined over intervals shorter than 4 hours.

  3. Development of Vertical Cable Seismic System

    Science.gov (United States)

    Asakawa, E.; Murakami, F.; Sekino, Y.; Okamoto, T.; Ishikawa, K.; Tsukahara, H.; Shimura, T.

    2011-12-01

    In 2009, Ministry of Education, Culture, Sports, Science and Technology(MEXT) started the survey system development for Hydrothermal deposit. We proposed the Vertical Cable Seismic (VCS), the reflection seismic survey with vertical cable above seabottom. VCS has the following advantages for hydrothermal deposit survey. (1) VCS is an efficient high-resolution 3D seismic survey in limited area. (2) It achieves high-resolution image because the sensors are closely located to the target. (3) It avoids the coupling problems between sensor and seabottom that cause serious damage of seismic data quality. (4) Because of autonomous recording system on sea floor, various types of marine source are applicable with VCS such as sea-surface source (GI gun etc.) , deep-towed or ocean bottom source. Our first experiment of 2D/3D VCS surveys has been carried out in Lake Biwa, JAPAN, in November 2009. The 2D VCS data processing follows the walk-away VSP, including wave field separation and depth migration. Seismic Interferometry technique is also applied. The results give much clearer image than the conventional surface seismic. Prestack depth migration is applied to 3D data to obtain good quality 3D depth volume. Seismic Interferometry technique is applied to obtain the high resolution image in the very shallow zone. Based on the feasibility study, we have developed the autonomous recording VCS system and carried out the trial experiment in actual ocean at the water depth of about 400m to establish the procedures of deployment/recovery and to examine the VC position or fluctuation at seabottom. The result shows that the VC position is estimated with sufficient accuracy and very little fluctuation is observed. Institute of Industrial Science, the University of Tokyo took the research cruise NT11-02 on JAMSTEC R/V Natsushima in February, 2011. In the cruise NT11-02, JGI carried out the second VCS survey using the autonomous VCS recording system with the deep towed source provided by

  4. Probabilistic Seismic Hazards Update for LLNL

    Energy Technology Data Exchange (ETDEWEB)

    Menchawi, O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fernandez, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-03-30

    Fugro Consultants, Inc. (FCL) completed the Probabilistic Seismic Hazard Analysis (PSHA) performed for Building 332 at the Lawrence Livermore National Laboratory (LLNL), near Livermore, CA. The study performed for the LLNL site includes a comprehensive review of recent information relevant to the LLNL regional tectonic setting and regional seismic sources in the vicinity of the site and development of seismic wave transmission characteristics. The Seismic Source Characterization (SSC), documented in Project Report No. 2259-PR-02 (FCL, 2015b), and Ground Motion Characterization (GMC), documented in Project Report No. 2259-PR-06 (FCL, 2015a) were developed in accordance with ANS/ANSI 2.29- 2008 Level 2 PSHA guidelines. The ANS/ANSI 2.29-2008 Level 2 PSHA framework is documented in Project Report No. 2259-PR-05 (FCL, 2016a). The Hazard Input Document (HID) for input into the PSHA developed from the SSC and GMC is presented in Project Report No. 2259-PR-04 (FCL, 2016b). The site characterization used as input for development of the idealized site profiles including epistemic uncertainty and aleatory variability is presented in Project Report No. 2259-PR-03 (FCL, 2015c). The PSHA results are documented in Project Report No. 2259-PR-07 (FCL, 2016c).

  5. First Quarter Hanford Seismic Report for Fiscal Year 2011

    Energy Technology Data Exchange (ETDEWEB)

    Rohay, Alan C.; Sweeney, Mark D.; Clayton, Ray E.; Devary, Joseph L.

    2011-03-31

    The Hanford Seismic Assessment Program (HSAP) provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network for the U.S. Department of Energy and its contractors. The HSAP is responsible for locating and identifying sources of seismic activity and monitoring changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management, natural phenomena hazards assessments, and engineering design and construction. In addition, the HSAP works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The Hanford Seismic Network and the Eastern Washington Regional Network consist of 44 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Assessment Team. The Hanford Seismic Network recorded 16 local earthquakes during the first quarter of FY 2011. Six earthquakes were located at shallow depths (less than 4 km), seven earthquakes at intermediate depths (between 4 and 9 km), most likely in the pre-basalt sediments, and three earthquakes were located at depths greater than 9 km, within the basement. Geographically, thirteen earthquakes were located in known swarm areas and three earthquakes were classified as random events. The highest magnitude event (1.8 Mc) was recorded on October 19, 2010 at depth 17.5 km with epicenter located near the Yakima River between the Rattlesnake Mountain and Horse Heaven Hills swarm areas.

  6. Evaluation of seismic hazard at the northwestern part of Egypt

    Science.gov (United States)

    Ezzelarab, M.; Shokry, M. M. F.; Mohamed, A. M. E.; Helal, A. M. A.; Mohamed, Abuoelela A.; El-Hadidy, M. S.

    2016-01-01

    The objective of this study is to evaluate the seismic hazard at the northwestern Egypt using the probabilistic seismic hazard assessment approach. The Probabilistic approach was carried out based on a recent data set to take into account the historic seismicity and updated instrumental seismicity. A homogenous earthquake catalogue was compiled and a proposed seismic sources model was presented. The doubly-truncated exponential model was adopted for calculations of the recurrence parameters. Ground-motion prediction equations that recently recommended by experts and developed based upon earthquake data obtained from tectonic environments similar to those in and around the studied area were weighted and used for assessment of seismic hazard in the frame of logic tree approach. Considering a grid of 0.2° × 0.2° covering the study area, seismic hazard curves for every node were calculated. Hazard maps at bedrock conditions were produced for peak ground acceleration, in addition to six spectral periods (0.1, 0.2, 0.3, 1.0, 2.0 and 3.0 s) for return periods of 72, 475 and 2475 years. The unified hazard spectra of two selected rock sites at Alexandria and Mersa Matruh Cities were provided. Finally, the hazard curves were de-aggregated to determine the sources that contribute most of hazard level of 10% probability of exceedance in 50 years for the mentioned selected sites.

  7. Seismic Risk Assessment for the Kyrgyz Republic

    Science.gov (United States)

    Pittore, Massimiliano; Sousa, Luis; Grant, Damian; Fleming, Kevin; Parolai, Stefano; Fourniadis, Yannis; Free, Matthew; Moldobekov, Bolot; Takeuchi, Ko

    2017-04-01

    The Kyrgyz Republic is one of the most socially and economically dynamic countries in Central Asia, and one of the most endangered by earthquake hazard in the region. In order to support the government of the Kyrgyz Republic in the development of a country-level Disaster Risk Reduction strategy, a comprehensive seismic risk study has been developed with the support of the World Bank. As part of this project, state-of-the-art hazard, exposure and vulnerability models have been developed and combined into the assessment of direct physical and economic risk on residential, educational and transportation infrastructure. The seismic hazard has been modelled with three different approaches, in order to provide a comprehensive overview of the possible consequences. A probabilistic seismic hazard assessment (PSHA) approach has been used to quantitatively evaluate the distribution of expected ground shaking intensity, as constrained by the compiled earthquake catalogue and associated seismic source model. A set of specific seismic scenarios based on events generated from known fault systems have been also considered, in order to provide insight on the expected consequences in case of strong events in proximity of densely inhabited areas. Furthermore, long-span catalogues of events have been generated stochastically and employed in the probabilistic analysis of expected losses over the territory of the Kyrgyz Republic. Damage and risk estimates have been computed by using an exposure model recently developed for the country, combined with the assignment of suitable fragility/vulnerability models. The risk estimation has been carried out with spatial aggregation at the district (rayon) level. The obtained results confirm the high level of seismic risk throughout the country, also pinpointing the location of several risk hotspots, particularly in the southern districts, in correspondence with the Ferghana valley. The outcome of this project will further support the local

  8. Seismic Device UVS 1504, possibilities of its Utilization

    Directory of Open Access Journals (Sweden)

    Leššo Igor

    1996-09-01

    Full Text Available Department of Mining and Geotechnics for many years deals with questions of the technical seismicity. In the paper are given possibilities of utilizing the UVS 1504 device and results obtained from the measurement of seismic effects of blasting as well as others sources of bursts. The measurements showed that this device enables to measure parameters and to evaluate measured data quickly, reliably, and with a very high precision. The device enables evaluating individual time degrees of blasts, determining the law of attenuation of the seismic waves, and precise determination of the maximum charge permissible for futher advance of the blasting in given conditions.

  9. Probabilistic seismic hazard maps for the North Balkan region

    Directory of Open Access Journals (Sweden)

    R. M. W. Musson

    1999-06-01

    Full Text Available A set of seismic hazard maps, expressed as horizontal peak ground acceleration, have been computed for a large area of Central and Eastern Europe covering the North Balkan area (Former Yugoslavia, Hungary, Romania. These are based on: a a compound earthquake catalogue for the region; b a seismic source model of 50 zones compiled on the basis of tectonic divisions and seismicity, and c a probabilistic methodology using stochastic (Monte Carlo modelling. It is found that the highest hazard in the region comes from intermediate focus earthquakes occurring in the Vrancea seismic zone; here the hazard exceeds 0.4 g at return periods of 475 years. Special account has been taken of the directional nature of attenuation from this source.

  10. Bias Errors in Measurement of Vibratory Power and Implication for Active Control of Structural Vibration

    DEFF Research Database (Denmark)

    Ohlrich, Mogens; Henriksen, Eigil; Laugesen, Søren

    1997-01-01

    errors can be largely compensated for by an absolute calibration of the transducers and inverse filtering that results in very small residual errors. Experimental results of this study indicate that these uncertainties will be in the order of one percent with respect to amplitude and two tenth......Uncertainties in power measurements performed with piezoelectric accelerometers and force transducers are investigated. It is shown that the inherent structural damping of the transducers is responsible for a bias phase error, which typically is in the order of one degree. Fortunately, such bias...... of a degree for the phase. This implies that input power at a single point can be measured to within one dB in practical structures which possesses some damping. The uncertainty is increased, however, when sums of measured power contributions from more sources are to be minimised, as is the case in active...

  11. 3D Modelling of Seismically Active Parts of Underground Faults via Seismic Data Mining

    Science.gov (United States)

    Frantzeskakis, Theofanis; Konstantaras, Anthony

    2015-04-01

    During the last few years rapid steps have been taken towards drilling for oil in the western Mediterranean sea. Since most of the countries in the region benefit mainly from tourism and considering that the Mediterranean is a closed sea only replenishing its water once every ninety years careful measures are being taken to ensure safe drilling. In that concept this research work attempts to derive a three dimensional model of the seismically active parts of the underlying underground faults in areas of petroleum interest. For that purpose seismic spatio-temporal clustering has been applied to seismic data to identify potential distinct seismic regions in the area of interest. Results have been coalesced with two dimensional maps of underground faults from past surveys and seismic epicentres, having followed careful reallocation processing, have been used to provide information regarding the vertical extent of multiple underground faults in the region of interest. The end product is a three dimensional map of the possible underground location and extent of the seismically active parts of underground faults. Indexing terms: underground faults modelling, seismic data mining, 3D visualisation, active seismic source mapping, seismic hazard evaluation, dangerous phenomena modelling Acknowledgment This research work is supported by the ESPA Operational Programme, Education and Life Long Learning, Students Practical Placement Initiative. References [1] Alves, T.M., Kokinou, E. and Zodiatis, G.: 'A three-step model to assess shoreline and offshore susceptibility to oil spills: The South Aegean (Crete) as an analogue for confined marine basins', Marine Pollution Bulletin, In Press, 2014 [2] Ciappa, A., Costabile, S.: 'Oil spill hazard assessment using a reverse trajectory method for the Egadi marine protected area (Central Mediterranean Sea)', Marine Pollution Bulletin, vol. 84 (1-2), pp. 44-55, 2014 [3] Ganas, A., Karastathis, V., Moshou, A., Valkaniotis, S., Mouzakiotis

  12. Soil Profiles and Seismic Loading

    Directory of Open Access Journals (Sweden)

    Janotka, V.

    2006-01-01

    Full Text Available The contribution estimates different geotechnical profiles of site condition change and their influences on the computed seismic response spectra and time histories final values and forms applying on the seismic structures loading. The mentioned problems methodics attitude solution is based on the computed seismic motion parameters.

  13. Assessment of wind turbine seismic risk : existing literature and simple study of tower moment demand.

    Energy Technology Data Exchange (ETDEWEB)

    Prowell, Ian (University of California, San Diego, CA); Veers, Paul S.

    2009-03-01

    Various sources of risk exist for all civil structures, one of which is seismic risk. As structures change in scale, the magnitude of seismic risk changes relative to risk from other sources. This paper presents an introduction to seismic hazard as applied to wind turbine structures. The existing design methods and research regarding seismic risk for wind turbines is then summarized. Finally a preliminary assessment is made based on current guidelines to understand how tower moment demand scales as rated power increases. Potential areas of uncertainty in the application of the current guidelines are summarized.

  14. Single-block rockfall dynamics inferred from seismic signal analysis

    Science.gov (United States)

    Hibert, Clément; Malet, Jean-Philippe; Bourrier, Franck; Provost, Floriane; Berger, Frédéric; Bornemann, Pierrick; Tardif, Pascal; Mermin, Eric

    2017-05-01

    Seismic monitoring of mass movements can significantly help to mitigate the associated hazards; however, the link between event dynamics and the seismic signals generated is not completely understood. To better understand these relationships, we conducted controlled releases of single blocks within a soft-rock (black marls) gully of the Rioux-Bourdoux torrent (French Alps). A total of 28 blocks, with masses ranging from 76 to 472 kg, were used for the experiment. An instrumentation combining video cameras and seismometers was deployed along the travelled path. The video cameras allow reconstructing the trajectories of the blocks and estimating their velocities at the time of the different impacts with the slope. These data are compared to the recorded seismic signals. As the distance between the falling block and the seismic sensors at the time of each impact is known, we were able to determine the associated seismic signal amplitude corrected for propagation and attenuation effects. We compared the velocity, the potential energy lost, the kinetic energy and the momentum of the block at each impact to the true amplitude and the radiated seismic energy. Our results suggest that the amplitude of the seismic signal is correlated to the momentum of the block at the impact. We also found relationships between the potential energy lost, the kinetic energy and the seismic energy radiated by the impacts. Thanks to these relationships, we were able to retrieve the mass and the velocity before impact of each block directly from the seismic signal. Despite high uncertainties, the values found are close to the true values of the masses and the velocities of the blocks. These relationships allow for gaining a better understanding of the physical processes that control the source of high-frequency seismic signals generated by rockfalls.

  15. Probabilistic Seismic Hazard Disaggregation Analysis for the South of Portugal

    Science.gov (United States)

    Rodrigues, I.; Sousa, M.; Teves-Costa, P.

    2010-12-01

    Probabilistic seismic hazard disaggregation analysis was performed and seismic scenarios were identified for Southern Mainland Portugal. This region’s seismicity is characterized by small and moderate magnitude events and by the sporadic occurrence of large earthquakes (e.g. the 1755 Lisbon earthquake). Thus, the Portuguese Civil Protection Agency (ANPC) sponsored a collaborative research project for the study of the seismic and tsunami risks in the Algarve (project ERSTA). In the framework of this project, a series of new developments were obtained, namely the revision of the seismic catalogue (IM, 2008), the delineation of new seismogenic zones affecting the Algarve region, which reflects the growing knowledge of this region's seismotectonic context, the derivation of new spectral attenuation laws (Carvalho and Campos Costa, 2008) and the revision of the probabilistic seismic hazard (Sousa et al. 2008). Seismic hazard was disaggregated considering different spaces of random variables, namely, bivariate conditional hazard distributions of X-Y (seismic source latitude and longitude) and multivariate 4D conditional hazard distributions of M-(X-Y)-ɛ (ɛ - deviation of ground motion to the median value predicted by an attenuation model). These procedures were performed for the peak ground acceleration (PGA) and for the 5% damped 1.0 and 2.5 Hz spectral acceleration levels of three return periods: 95, 475 and 975 years. The seismic scenarios controlling the hazard of a given ground motion level, were identified as the modal values of the 4D disaggregation analysis for each of the 84 parishes of the Algarve region. Those scenarios, based on a probabilistic analysis, are meant to be used in the emergency planning as a complement to the historical scenarios that severely affected this region. Seismic scenarios share a few number of geographical locations for all return periods. Moreover, seismic hazard of most Algarve’s parishes is dominated by the seismicity located

  16. Seismic Swarms at Paricutin Volcano Area. Magmatic Intrusion or Tectonic Seismicity?

    Science.gov (United States)

    Pinzon, J. I.; Nunez-Cornu, F. J.; Escudero, C. R.; Rowe, C. A.

    2014-12-01

    We relocate a seismic swarm with more than 700 earthquakes that took place between May and June 2006 in the Paricutin volcano area, Mexico inside of the Michoacan monogenetic volcanic field. This seismic swarm was recorded by the project "Mapping the Riviera Subduction Zone" (MARS), a temporary seismic network that was installed in the states of Jalisco, Colima and Michoacán between January 2006 and June 2007. Previously seismic swarms in the area were reported in the years of 1997, 1999 and 2000. For one that took place in the year of 1997 the Servicio Sismologico Nacional deployed a local network in the area, they conclude that the source of the seismicity was tectonic with depths between 18 and 12 km. The episodes of 1999 and 2000 were reported as similar to the 1997 swarm. A previous analysis of the 2006 swarm concludes that the depth of seismicity migrates from 9 to 5 km and was originated by a magmatic intrusion. We did a relocation of this swarm reading all the events and using Hypo71 and the P-wave velocity model used by the Jalisco Seismic and Acelerometric Network; a waveform analysis using cross-correlation method was also carried out. We obtained 15 earthquakes families with a correlation factor equal or greater than 0.79 and composed focal mechanism for each family. These families present a migration in depth beginning at 16 km and ended at 9 km. Our results agrees with a magmatic intrusion, but not so shallow as the previous study of the 2006 swarm.

  17. Seismic Techniques for Subsurface Voids Detection

    Science.gov (United States)

    Gritto, Roland; Korneev, Valeri; Elobaid Elnaiem, Ali; Mohamed, Fathelrahman; Sadooni, Fadhil

    2016-04-01

    orthogonal transmission surveys to detect and locate the object. Furthermore, we showed that ambient noise recordings may generate data with sufficient signal-to-noise ratio to successfully detect and locate subsurface voids. Being able to use ambient noise recordings would eliminate the need to employ active seismic sources that are time consuming and more expensive to operate.

  18. Attenuation of Seismic Waves at Regional Distances

    Science.gov (United States)

    1983-02-18

    O.W. (1983). Empirical magnitude and spectral scaling relations for mid-plate and plate-margin earthquakes, A& S.J. Duda and K. Aki ( editors ... ijsmi % Ia=, aggtio in Western LM&R, Semi-Annual Technical Report No. 2, Rondout Associates, Inc., Stone Ridge, NY. 13 Magnitude Relations and Spectral...earthquakes, J& S.J. Duda and K. Aki ( editors ), Quantification of Earthquakes, Tectonoohvsics, 23 (in press). Nuttli, O.W. (1983b). Average seismic source

  19. Fresnel zone imaging of seismic data

    Science.gov (United States)

    Mullick, N.; Buske, S.

    2017-11-01

    Kirchhoff pre-stack depth migration (KPSDM) is a widely applied and powerful seismic imaging technique to obtain structural information of Earth's subsurface. Reflected waveforms recorded in a seismic section are smeared along reflection isochrons at respective recording times and an image of the subsurface is produced by constructive interference of the backprojected waveforms at the reflecting structures. The imaging technique is applicable with any arbitrary source and receiver geometry and to converted waves as well. However, it uses only the traveltime information of the waves and places a large amount of backprojected energy away from the reflectors to be imaged. The excessive smearing noise produced lowers the image quality considerably often hiding weaker reflectors and requires uniform and dense distribution of sources and receivers for the imaging scheme to work properly. The application of the technique is thus limited primarily to the active source reflection seismic data which usually have regular and abundant data coverage. In this study, we present a new seismic migration technique based on the KPSDM called the Fresnel zone imaging (FZI). In this approach, the reflected waveforms recorded at a receiver are smeared only to subsets of the reflection isochrons at respective recording times that lie on all potential Fresnel zones on all possible reflectors from which the recorded waves may originate; using the additional information of direction of incidence of the recorded waves at the receiver. As a result, the backprojection of the reflected waveforms is restricted to the actual Fresnel zones on the reflectors at which the reflected waves were generated. This produces minimal smearing noise enhancing the image quality significantly. It also enables the imaging scheme to work acceptably even with limited and irregular source and receiver distribution. Moreover, the principle can be readily extended to converted waves as well. Therefore, by employing

  20. Pre-seismic, co-seismic and post-seismic displacements associated ...

    Indian Academy of Sciences (India)

    Pre-seismic, co-seismic and post-seismic displacements associated with the Bhuj 2001 earthquake derived from recent and historic geodetic data. Sridevi Jade M Mukul I A Parvez M B Ananda P D Kumar V K Gaur R Bendick R Bilham F Blume K Wallace I A Abbasi M Asif Khan S Ulhadi. Volume 112 Issue 3 September ...

  1. Seismic II over I Drop Test Program results and interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, B.

    1993-03-01

    The consequences of non-seismically qualified (Category 2) objects falling and striking essential seismically qualified (Category 1) objects has always been a significant, yet analytically difficult problem, particularly in evaluating the potential damage to equipment that may result from earthquakes. Analytical solutions for impact problems are conservative and available for mostly simple configurations. In a nuclear facility, the {open_quotes}sources{close_quotes} and {open_quotes}targets{close_quotes} requiring evaluation are frequently irregular in shape and configuration, making calculations and computer modeling difficult. Few industry or regulatory rules are available on this topic even though it is a source of considerable construction upgrade costs. A drop test program was recently conducted to develop a more accurate understanding of the consequences of seismic interactions. The resulting data can be used as a means to improve the judgment of seismic qualification engineers performing interaction evaluations and to develop realistic design criteria for seismic interactions. Impact tests on various combinations of sources and targets commonly found in one Savannah River Site (SRS) nuclear facility were performed by dropping the sources from various heights onto the targets. This report summarizes results of the Drop Test Program. Force and acceleration time history data are presented as well as general observations on the overall ruggedness of various targets when subjected to impacts from different types of sources.

  2. Seismic II over I Drop Test Program results and interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, B.

    1993-03-01

    The consequences of non-seismically qualified (Category 2) objects falling and striking essential seismically qualified (Category 1) objects has always been a significant, yet analytically difficult problem, particularly in evaluating the potential damage to equipment that may result from earthquakes. Analytical solutions for impact problems are conservative and available for mostly simple configurations. In a nuclear facility, the [open quotes]sources[close quotes] and [open quotes]targets[close quotes] requiring evaluation are frequently irregular in shape and configuration, making calculations and computer modeling difficult. Few industry or regulatory rules are available on this topic even though it is a source of considerable construction upgrade costs. A drop test program was recently conducted to develop a more accurate understanding of the consequences of seismic interactions. The resulting data can be used as a means to improve the judgment of seismic qualification engineers performing interaction evaluations and to develop realistic design criteria for seismic interactions. Impact tests on various combinations of sources and targets commonly found in one Savannah River Site (SRS) nuclear facility were performed by dropping the sources from various heights onto the targets. This report summarizes results of the Drop Test Program. Force and acceleration time history data are presented as well as general observations on the overall ruggedness of various targets when subjected to impacts from different types of sources.

  3. RSEIS and RFOC: Seismic Analysis in R

    Science.gov (United States)

    Lees, J. M.

    2015-12-01

    Open software is essential for reproducible scientific exchange. R-packages provide a platform for development of seismological investigation software that can be properly documented and traced for data processing. A suite of R packages designed for a wide range of seismic analysis is currently available in the free software platform called R. R is a software platform based on the S-language developed at Bell Labs decades ago. Routines in R can be run as standalone function calls, or developed in object-oriented mode. R comes with a base set of routines, and thousands of user developed packages. The packages developed at UNC include subroutines and interactive codes for processing seismic data, analyzing geographic information (GIS) and inverting data involved in a variety of geophysical applications. On CRAN (Comprehensive R Archive Network, http://www.r-project.org/) currently available packages related to seismic analysis are RSEIS, Rquake, GEOmap, RFOC, zoeppritz, RTOMO, and geophys, Rwave, PEIP, hht, rFDSN. These include signal processing, data management, mapping, earthquake location, deconvolution, focal mechanisms, wavelet transforms, Hilbert-Huang Transforms, tomographic inversion, and Mogi deformation among other useful functionality. All software in R packages is required to have detailed documentation, making the exchange and modification of existing software easy. In this presentation, I will focus on packages RSEIS and RFOC, showing examples from a variety of seismic analyses. The R approach has similarities to the popular (and expensive) MATLAB platform, although R is open source and free to down load.

  4. Mobile seismic exploration

    Energy Technology Data Exchange (ETDEWEB)

    Dräbenstedt, A., E-mail: a.draebenstedt@polytec.de, E-mail: rembe@iei.tu-clausthal.de, E-mail: ulrich.polom@liag-hannover.de; Seyfried, V. [Research & Development, Polytec GmbH, Waldbronn (Germany); Cao, X.; Rembe, C., E-mail: a.draebenstedt@polytec.de, E-mail: rembe@iei.tu-clausthal.de, E-mail: ulrich.polom@liag-hannover.de [Institute of Electrical Information Technology, TU Clausthal, Clausthal-Zellerfeld (Germany); Polom, U., E-mail: a.draebenstedt@polytec.de, E-mail: rembe@iei.tu-clausthal.de, E-mail: ulrich.polom@liag-hannover.de [Leibniz Institute of Applied Geophysics, Hannover (Germany); Pätzold, F.; Hecker, P. [Institute of Flight Guidance, TU Braunschweig, Braunschweig (Germany); Zeller, T. [Clausthaler Umwelttechnik Institut CUTEC, Clausthal-Zellerfeld (Germany)

    2016-06-28

    Laser-Doppler-Vibrometry (LDV) is an established technique to measure vibrations in technical systems with picometer vibration-amplitude resolution. Especially good sensitivity and resolution can be achieved at an infrared wavelength of 1550 nm. High-resolution vibration measurements are possible over more than 100 m distance. This advancement of the LDV technique enables new applications. The detection of seismic waves is an application which has not been investigated so far because seismic waves outside laboratory scales are usually analyzed at low frequencies between approximately 1 Hz and 250 Hz and require velocity resolutions in the range below 1 nm/s/√Hz. Thermal displacements and air turbulence have critical influences to LDV measurements at this low-frequency range leading to noise levels of several 100 nm/√Hz. Commonly seismic waves are measured with highly sensitive inertial sensors (geophones or Micro Electro-Mechanical Sensors (MEMS)). Approaching a laser geophone based on LDV technique is the topic of this paper. We have assembled an actively vibration-isolated optical table in a minivan which provides a hole in its underbody. The laser-beam of an infrared LDV assembled on the optical table impinges the ground below the car through the hole. A reference geophone has detected remaining vibrations on the table. We present the results from the first successful experimental demonstration of contactless detection of seismic waves from a movable vehicle with a LDV as laser geophone.

  5. Understanding induced seismicity

    NARCIS (Netherlands)

    Elsworth, Derek; Spiers, Christopher J.|info:eu-repo/dai/nl/304829323; Niemeijer, Andre R.|info:eu-repo/dai/nl/370832132

    2016-01-01

    Fluid injection–induced seismicity has become increasingly widespread in oil- and gas-producing areas of the United States (1–3) and western Canada. It has shelved deep geothermal energy projects in Switzerland and the United States (4), and its effects are especially acute in Oklahoma, where

  6. Seismic surveys test on Innerhytta Pingo, Adventdalen, Svalbard Islands

    Science.gov (United States)

    Boaga, Jacopo; Rossi, Giuliana; Petronio, Lorenzo; Accaino, Flavio; Romeo, Roberto; Wheeler, Walter

    2015-04-01

    We present the preliminary results of an experimental full-wave seismic survey test conducted on the Innnerhytta a Pingo, located in the Adventdalen, Svalbard Islands, Norway. Several seismic surveys were adopted in order to study a Pingo inner structure, from classical reflection/refraction arrays to seismic tomography and surface waves analysis. The aim of the project IMPERVIA, funded by Italian PNRA, was the evaluation of the permafrost characteristics beneath this open-system Pingo by the use of seismic investigation, evaluating the best practice in terms of logistic deployment. The survey was done in April-May 2014: we collected 3 seismic lines with different spacing between receivers (from 2.5m to 5m), for a total length of more than 1 km. We collected data with different vertical geophones (with natural frequency of 4.5 Hz and 14 Hz) as well as with a seismic snow-streamer. We tested different seismic sources (hammer, seismic gun, fire crackers and heavy weight drop), and we verified accurately geophone coupling in order to evaluate the different responses. In such peculiar conditions we noted as fire-crackers allow the best signal to noise ratio for refraction/reflection surveys. To ensure the best geophones coupling with the frozen soil, we dug snow pits, to remove the snow-cover effect. On the other hand, for the surface wave methods, the very high velocity of the permafrost strongly limits the generation of long wavelengths both with these explosive sources as with the common sledgehammer. The only source capable of generating low frequencies was a heavy drop weight system, which allows to analyze surface wave dispersion below 10 Hz. Preliminary data analysis results evidence marked velocity inversions and strong velocity contrasts in depth. The combined use of surface and body waves highlights the presence of a heterogeneous soil deposit level beneath a thick layer of permafrost. This is the level that hosts the water circulation from depth controlling

  7. Kernel Smoothing Methods for Non-Poissonian Seismic Hazard Analysis

    Science.gov (United States)

    Woo, Gordon

    2017-04-01

    For almost fifty years, the mainstay of probabilistic seismic hazard analysis has been the methodology developed by Cornell, which assumes that earthquake occurrence is a Poisson process, and that the spatial distribution of epicentres can be represented by a set of polygonal source zones, within which seismicity is uniform. Based on Vere-Jones' use of kernel smoothing methods for earthquake forecasting, these methods were adapted in 1994 by the author for application to probabilistic seismic hazard analysis. There is no need for ambiguous boundaries of polygonal source zones, nor for the hypothesis of time independence of earthquake sequences. In Europe, there are many regions where seismotectonic zones are not well delineated, and where there is a dynamic stress interaction between events, so that they cannot be described as independent. From the Amatrice earthquake of 24 August, 2016, the subsequent damaging earthquakes in Central Italy over months were not independent events. Removing foreshocks and aftershocks is not only an ill-defined task, it has a material effect on seismic hazard computation. Because of the spatial dispersion of epicentres, and the clustering of magnitudes for the largest events in a sequence, which might all be around magnitude 6, the specific event causing the highest ground motion can vary from one site location to another. Where significant active faults have been clearly identified geologically, they should be modelled as individual seismic sources. The remaining background seismicity should be modelled as non-Poissonian using statistical kernel smoothing methods. This approach was first applied for seismic hazard analysis at a UK nuclear power plant two decades ago, and should be included within logic-trees for future probabilistic seismic hazard at critical installations within Europe. In this paper, various salient European applications are given.

  8. Finite-difference modeling experiments for seismic interferometry

    NARCIS (Netherlands)

    Thorbecke, J.W.; Draganov, D.

    2011-01-01

    In passive seismic interferometry, new reflection data can be retrieved by crosscorrelating recorded noise data. The quality of the retrieved reflection data is, among others, dependent on the duration and number of passive sources present during the recording time, the source distribution, and the

  9. Pre-Eruptive Seismic Tremor Signals During the Bardarbunga Eruption, Iceland

    Science.gov (United States)

    Eibl, Eva P. S.; Bean, Christopher J.; Vogfjörd, Kristin S.; Lokmer, Ivan; Möllhoff, Martin; Ying, Yingzi; O'Brien, Gareth; Pálsson, Finnur

    2017-04-01

    The eruption of Bardarbunga volcano in Iceland in 2014/15 was preceded by two weeks of increased seismicity, seismic tremor, deformation and superficial faulting and graben formation. Propagating seismicity at 3 to 8 km depth was interpreted as the formation of a dyke while flow of magma was inferred from modelling of geodetic signals at slightly shallower depth. We present the pre-eruptive seismic activity with a focus on seismic tremor. We analyse and locate the pre-eruptive tremor with a seismic array and an amplitude-based location method that together could resolve both lateral and upwards tremor source migration. We estimate the depth range of the source using numerical simulations and compare our results with hydrological and glaciological observations such as the formation of depressions (so called cauldrons) on the glacier surface. Our results indicate that tremor occurred pre-eruptively and can be linked to the gradual opening of the shallow crust shortly before an eruption started.

  10. Seismic risk analysis for General Electric Plutonium Facility, Pleasanton, California. Final report, part II

    Energy Technology Data Exchange (ETDEWEB)

    1980-06-27

    This report is the second of a two part study addressing the seismic risk or hazard of the special nuclear materials (SNM) facility of the General Electric Vallecitos Nuclear Center at Pleasanton, California. The Part I companion to this report, dated July 31, 1978, presented the seismic hazard at the site that resulted from exposure to earthquakes on the Calaveras, Hayward, San Andreas and, additionally, from smaller unassociated earthquakes that could not be attributed to these specific faults. However, while this study was in progress, certain additional geologic information became available that could be interpreted in terms of the existance of a nearby fault. Although substantial geologic investigations were subsequently deployed, the existance of this postulated fault, called the Verona Fault, remained very controversial. The purpose of the Part II study was to assume the existance of such a capable fault and, under this assumption, to examine the loads that the fault could impose on the SNM facility. This report first reviews the geologic setting with a focus on specifying sufficient geologic parameters to characterize the postulated fault. The report next presents the methodology used to calculate the vibratory ground motion hazard. Because of the complexity of the fault geometry, a slightly different methodology is used here compared to the Part I report. This section ends with the results of the calculation applied to the SNM facility. Finally, the report presents the methodology and results of the rupture hazard calculation.

  11. Studies of infrasound propagation using the USArray seismic network (Invited)

    Science.gov (United States)

    Hedlin, M. A.; Degroot-Hedlin, C. D.; Walker, K. T.

    2010-12-01

    Although there are currently ~ 100 infrasound arrays worldwide, more than ever before, the station density is still insufficient to provide validation for detailed propagation modeling. Much structure in the atmosphere is short-lived and occurs at spatial scales much smaller than the average distance between infrasound stations. Relatively large infrasound signals can be observed on seismic channels due to coupling at the Earth's surface. Recent research, using data from the 70-km spaced 400-station USArray and other seismic network deployments, has shown the value of dense seismic network data for filling in the gaps between infrasound arrays. The dense sampling of the infrasound wavefield has allowed us to observe complete travel-time branches of infrasound signals and shed more light on the nature of infrasound propagation. We present early results from our studies of impulsive atmospheric sources, such as series of UTTR rocket motor detonations in Utah. The Utah blasts have been well recorded by USArray seismic stations and infrasound arrays in Nevada and Washington State. Recordings of seismic signals from a series of six events in 2007 are used to pinpoint the shot times to anticipate studying dense acoustic network recordings as the USArray is currently being upgraded with infrasound microphones. These new sensors will allow us to make semi-continental scale network recordings of infrasound signals free of concerns about how the signals observed on seismic channels were modified when being coupled to seismic.

  12. Seismic refraction survey of the ANS preferred site

    Energy Technology Data Exchange (ETDEWEB)

    Davis, R.K. [Automated Sciences Group, Inc., Oak Ridge, TN (United States); Hopkins, R.A. [Marrich, Inc., Knoxville, TN (United States); Doll, W.E. [Oak Ridge National Lab., TN (United States)

    1992-02-01

    Between September 19, 1991 and October 8, 1991 personnel from Martin Marietta Energy Systems, Inc. (Energy Systems), Automated Sciences Group, Inc., and Marrich, Inc. performed a seismic refraction survey at the Advanced Neutron Source (ANS) preferred site. The purpose of this survey was to provide estimates of top-of-rock topography, based on seismic velocities, and to delineate variations in rock and soil velocities. Forty-four seismic refraction spreads were shot to determine top-of-rock depths at 42 locations. Nine of the seismic spreads were shot with long offsets to provide 216 top-of-rock depths for 4 seismic refraction profiles. The refraction spread locations were based on the grid for the ANS Phase I drilling program. Interpretation of the seismic refraction data supports the assumption that the top-of-rock surface generally follows the local topography. The shallow top-of-rock interface interpreted from the seismic refraction data is also supported by limited drill information at the site. Some zones of anomalous data are present that could be the result of locally variable weathering, a localized variation in shale content, or depth to top-of-rock greater than the site norm.

  13. Multiscale seismic characterization of marine sediments by using a wavelet-based approach

    Science.gov (United States)

    Ker, Stephan; Le Gonidec, Yves; Gibert, Dominique

    2015-04-01

    We propose a wavelet-based method to characterize acoustic impedance discontinuities from a multiscale analysis of reflected seismic waves. This method is developed in the framework of the wavelet response (WR) where dilated wavelets are used to sound a complex seismic reflector defined by a multiscale impedance structure. In the context of seismic imaging, we use the WR as a multiscale seismic attributes, in particular ridge functions which contain most of the information that quantifies the complex geometry of the reflector. We extend this approach by considering its application to analyse seismic data acquired with broadband but frequency limited source signals. The band-pass filter related to such actual sources distort the WR: in order to remove these effects, we develop an original processing based on fractional derivatives of Lévy alpha-stable distributions in the formalism of the continuous wavelet transform (CWT). We demonstrate that the CWT of a seismic trace involving such a finite frequency bandwidth can be made equivalent to the CWT of the impulse response of the subsurface and is defined for a reduced range of dilations, controlled by the seismic source signal. In this dilation range, the multiscale seismic attributes are corrected from distortions and we can thus merge multiresolution seismic sources to increase the frequency range of the mutliscale analysis. As a first demonstration, we perform the source-correction with the high and very high resolution seismic sources of the SYSIF deep-towed seismic device and we show that both can now be perfectly merged into an equivalent seismic source with an improved frequency bandwidth (220-2200 Hz). Such multiresolution seismic data fusion allows reconstructing the acoustic impedance of the subseabed based on the inverse wavelet transform properties extended to the source-corrected WR. We illustrate the potential of this approach with deep-water seismic data acquired during the ERIG3D cruise and we compare

  14. Broadband spectra of seismic survey air-gun emissions, with reference to dolphin auditory thresholds.

    Science.gov (United States)

    Goold, J C; Fish, P J

    1998-04-01

    Acoustic emissions from a 2120 cubic in air-gun array were recorded through a towed hydrophone assembly during an oil industry 2-D seismic survey off the West Wales Coast of the British Isles. Recorded seismic pulses were sampled, calibrated, and analyzed post-survey to investigate power levels of the pulses in the band 200 Hz-22 kHz at 750-m, 1-km, 2.2-km, and 8-km range from source. At 750-m range from source, seismic pulse power at the 200-Hz end of the spectrum was 140 dB re: 1 microPa2/Hz, and at the 20-kHz end of the spectrum seismic pulse power was 90 dB re: 1 microPa2/Hz. Although the background noise levels of the seismic recordings were far in excess of ambient, due to the proximity of engine, propeller, and flow sources of the ship towing the hydrophone, seismic power dominated the entire recorded bandwidth of 200 Hz-22 kHz at ranges of up to 2 km from the air-gun source. Even at 8-km range seismic power was still clearly in excess of the high background noise levels up to 8 kHz. Acoustic observations of common dolphins during preceding seismic surveys suggest that these animals avoided the immediate vicinity of the air-gun array while firing was in progress, i.e., localized disturbance occurred during seismic surveying. Although a general pattern of localized disturbance is suggested, one specific observation revealed that common dolphins were able to tolerate the seismic pulses at 1-km range from the air-gun array. Given the high broadband seismic pulse power levels across the entire recorded bandwidth, and known auditory thresholds for several dolphin species, we consider such seismic emissions to be clearly audible to dolphins across a bandwidth of tens on kilohertz, and at least out to 8-km range.

  15. Joint Bayesian Stochastic Inversion of Well Logs and Seismic Data for Volumetric Uncertainty Analysis

    OpenAIRE

    Moslem Moradi; Omid Asghari; Gholamhossein Norouzi; Mohammad Riahi; Reza Sokooti

    2015-01-01

    Here in, an application of a new seismic inversion algorithm in one of Iran’s oilfields is described. Stochastic (geostatistical) seismic inversion, as a complementary method to deterministic inversion, is perceived as contribution combination of geostatistics and seismic inversion algorithm. This method integrates information from different data sources with different scales, as prior information in Bayesian statistics. Data integration leads to a probability density function (named as a pos...

  16. Signal Apparition - A seismic shift for imaging the Earth's interior

    Science.gov (United States)

    Robertsson, Johan; Amundsen, Lasse; van Manen, Dirk-Jan; Andersson, Fredrik; Eggenberger, Kurt; Pedersen, Åsmund; Thompson, Mark; Schmelzbach, Cedric

    2017-04-01

    The concept of signal apparition, introduced by Robertsson et al. (2016), offers a new perspective on the sampling of seismic wavefields. Signal apparition has range of applications in seismic data processing and imaging. In particular, for simultaneous source data acquisition, and through the use of periodic source modulation functions to encode sources during simultaneous shooting, energy can be partially injected or "apparated" along the wavenumber axis in the frequency-wavenumber (f-k) domain that would otherwise not be occupied by any signal. In the non-overlapping regions of the f-k domain, the individual sources can be exactly recovered by using linear combinations of weighted versions of the apparated data. In this fashion, the cost of acquiring a seismic survey can be reduced proportionally to the number of sources that can be activated simultaneously - thus enabling very significant cost reductions and/or increased image quality. We present results from an exploration scale simultaneous source field test carried out over a producing hydrocarbon reservoir in the North Sea in 2016. The test demonstrates excellent results with unprecedented low-noise separated results fit for time-lapse reservoir analysis. We expect that signal apparition will also transform the way that imaging of the Earth's deeper structure in the crust and mantle is carried out during refraction and reflection seismic experiments. In particular our acquisition approach will allow for 3D imaging using 2D-like acquisition geometries and will also allow for a significant increase in data quality in the low-frequency band below 5Hz. We will discuss specific seismic data acquisition configurations that will allow for a step-change in imaging of crustal-scale Earth structures without significantly increasing acquisition cost compared to current practice for academic seismic data experimentation. Robertsson, J. O. A., Amundsen, L. and Pedersen, Å. S. [2016]. Express Letter: Signal apparition

  17. Updating the USGS seismic hazard maps for Alaska

    Science.gov (United States)

    Mueller, Charles; Briggs, Richard; Wesson, Robert L.; Petersen, Mark D.

    2015-01-01

    The U.S. Geological Survey makes probabilistic seismic hazard maps and engineering design maps for building codes, emergency planning, risk management, and many other applications. The methodology considers all known earthquake sources with their associated magnitude and rate distributions. Specific faults can be modeled if slip-rate or recurrence information is available. Otherwise, areal sources are developed from earthquake catalogs or GPS data. Sources are combined with ground-motion estimates to compute the hazard. The current maps for Alaska were developed in 2007, and included modeled sources for the Alaska-Aleutian megathrust, a few crustal faults, and areal seismicity sources. The megathrust was modeled as a segmented dipping plane with segmentation largely derived from the slip patches of past earthquakes. Some megathrust deformation is aseismic, so recurrence was estimated from seismic history rather than plate rates. Crustal faults included the Fairweather-Queen Charlotte system, the Denali–Totschunda system, the Castle Mountain fault, two faults on Kodiak Island, and the Transition fault, with recurrence estimated from geologic data. Areal seismicity sources were developed for Benioff-zone earthquakes and for crustal earthquakes not associated with modeled faults. We review the current state of knowledge in Alaska from a seismic-hazard perspective, in anticipation of future updates of the maps. Updated source models will consider revised seismicity catalogs, new information on crustal faults, new GPS data, and new thinking on megathrust recurrence, segmentation, and geometry. Revised ground-motion models will provide up-to-date shaking estimates for crustal earthquakes and subduction earthquakes in Alaska.

  18. Linearized inversion frameworks toward high-resolution seismic imaging

    KAUST Repository

    Aldawood, Ali

    2016-09-01

    Seismic exploration utilizes controlled sources, which emit seismic waves that propagate through the earth subsurface and get reflected off subsurface interfaces and scatterers. The reflected and scattered waves are recorded by recording stations installed along the earth surface or down boreholes. Seismic imaging is a powerful tool to map these reflected and scattered energy back to their subsurface scattering or reflection points. Seismic imaging is conventionally based on the single-scattering assumption, where only energy that bounces once off a subsurface scatterer and recorded by a receiver is projected back to its subsurface position. The internally multiply scattered seismic energy is considered as unwanted noise and is usually suppressed or removed from the recorded data. Conventional seismic imaging techniques yield subsurface images that suffer from low spatial resolution, migration artifacts, and acquisition fingerprint due to the limited acquisition aperture, number of sources and receivers, and bandwidth of the source wavelet. Hydrocarbon traps are becoming more challenging and considerable reserves are trapped in stratigraphic and pinch-out traps, which require highly resolved seismic images to delineate them. This thesis focuses on developing and implementing new advanced cost-effective seismic imaging techniques aiming at enhancing the resolution of the migrated images by exploiting the sparseness of the subsurface reflectivity distribution and utilizing the multiples that are usually neglected when imaging seismic data. I first formulate the seismic imaging problem as a Basis pursuit denoise problem, which I solve using an L1-minimization algorithm to obtain the sparsest migrated image corresponding to the recorded data. Imaging multiples may illuminate subsurface zones, which are not easily illuminated by conventional seismic imaging using primary reflections only. I then develop an L2-norm (i.e. least-squares) inversion technique to image

  19. Ultraviolet-LIGA-based fabrication and characterization of a nonresonant drive-mode vibratory gyro/accelerometer

    Science.gov (United States)

    Verma, Payal; Zaman Khan, Khamar; Khonina, Svetlana Nikolaevna; Kazanskiy, Nikolay Lvovich; Gopal, Ram

    2016-07-01

    A dual-purpose nonresonant 2-degrees of freedom (DOF) drive-mode and 1-DOF sense-mode vibratory gyro/accelerometer fabricated using the economical ultraviolet-lithographie-galvanoformung-abformung (UV-LIGA) fabrication process using SU-8 photoresist is reported. The dual-purpose device presented is capable of detecting acceleration at the lower-frequency band and angular rate at the operating frequency band thereby functioning as both accelerometer and gyroscope. This is achieved by designing the structure such that the frequency response of the drive oscillator has two drive resonances with a flat zone between them, while the sense oscillator has one resonance, which is deliberately placed in the flat region between the two drive resonances. For angular rate detection, the device is operated in the flat zone at the sense resonance frequency at which the device is less susceptible to frequency variations due to both environmental variation and fabrication imperfections and hence is said to be operating in robust mode. The steady-state response and discrimination for angular rate and acceleration sensing have been devised using analytical modeling. The fabrication process is optimized to realize a gyro/accelerometer that has a 9-μm-thick nickel structural layer and 4-μm capacitive gaps. The overall miniature device size is 2.0 mm×1.9 mm. The experimental frequency response of the fabricated devices shows drive-mode resonances at 2.85 and 4.96 kHz and sense resonance at 3.85 kHz compared to the respective design values of drive-mode resonance frequencies 2.97 and 4.81 kHz and sense resonance frequency of 4 kHz. To demonstrate the dual-purpose capability of the device, acceleration characterization has been carried out and presented. The fabricated sensor is packaged in a ceramic package and interfaced with a MS3110 differential capacitive read out IC to characterize the acceleration response of the sensor, using an out-of-plane shaker. The bandwidth for

  20. Seismic Hazard Implication of the Seismotectonics of southern Africa

    Science.gov (United States)

    Midzi, Vunganai; Mulabisana, Thifelimbilu; Manzunzu, Brassnavy

    2014-05-01

    The work presented in this report / presentation was prepared as part of the requirements for the SIDA/IGCP Project 601 titled "Seismotectonics and Seismic Hazards in Africa" as well as part of the seismic source characterisation of the GEM-Africa Seismic hazard study. An effort was made to compile information necessary to prepare a seismotectonic map of Africa which can then be used in carrying out a seismic hazard assessment of the continent or locations within the continent. Information on major faults, fault plane solutions, geophysical data as well as stress data has so far been collected and included in a database for the southern Africa region. Reports published by several experts contributed much to the collected information. The seismicity data used are part of the earthquake catalogue being prepared for the GEM-Africa project, which includes historical and instrumental records as collected from various sources. An effort has been made to characterise the identified major faults and through further analysis investigate their possible impact on the seismic hazard of southern Africa.

  1. Influence of seismicity on the Lusi mud eruption

    Science.gov (United States)

    Rudolph, Maxwell L.; Manga, Michael; Tingay, Mark; Davies, Richard J.

    2015-09-01

    Earthquakes trigger the eruption of mud and magmatic volcanoes and influence ongoing eruptive activity. One mechanism that could trigger an eruption is clay liquefaction. Here we model the propagation of seismic waves beneath the Lusi mud eruption (East Java, Indonesia) using available seismic velocity and density models to assess the effect of subsurface structure on the amplification of incident seismic waves. We find that using an updated subsurface density and velocity structure, there is no significant amplification of incident seismic energy in the Upper Kalibeng Formation, the source of the erupting solids. Hence, the hypothesis that the Lusi eruption was triggered by clay liquefaction appears unlikely to be correct. Independent constraints from gas chemistry as well as analyses of drilling activities at the nearby Banjar-Panji 1 gas exploration well and an analysis of the effects of other earthquakes all favor a drilling trigger.

  2. Probabilistic modeling of caprock leakage from seismic reflection data

    DEFF Research Database (Denmark)

    Zunino, Andrea; Hansen, Thomas Mejer; Bergjofd-Kitterød, Ingjerd

    data, etc.) and test them to find out which models satisfy the observed seismic data. Our algorithm samples the probability distributions of reservoir parameters, including the distribution of a rough measure of the overall transmissivity of the caprock, so that finally a set of solutions containing...... within the storage complexes. The geological models are built on top of geophysical data such as seismic surveys, geological information and well logs from the reservoir or nearby regions. The risk assessment of CO2 storage requires a careful analysis which accounts for all sources of uncertainty...... simplifications, we propose a consistent combined seismic and petrophysical modeling in a probabilistic framework. We model the reservoir as a simplified synthetic 2-D pixel-based model, parametrized through rock type, seismic P-wave velocity, density and porosity at each point of a regular grid. Uncertainties...

  3. Spatial Seismicity Rates and Maximum Magnitudes for Background Earthquakes

    Science.gov (United States)

    Petersen, Mark D.; Mueller, Charles S.; Frankel, Arthur D.; Zeng, Yuehua

    2008-01-01

    The background seismicity model is included to account for M 5.0 - 6.5 earthquakes on faults and for random M 5.0 ? 7.0 earthquakes that do not occur on faults included in the model (as in earlier models of Frankel et al., 1996, 2002 and Petersen et al., 1996). We include four different classes of earthquake sources in the California background seismicity model: (1) gridded (smoothed) seismicity, (2) regional background zones, (3) special fault zone models, and (4) shear zones (also referred to as C zones). The gridded (smoothed) seismicity model, the regional background zone model, and the special fault zones use a declustered earthquake catalog for calculation of earthquake rates. Earthquake rates in shear zones are estimated from the geodetically determined rate of deformation across an area of high strain rate. We use a truncated exponential (Gutenberg-Richter, 1944) magnitude-frequency distribution to account for earthquakes in the background models.

  4. Seismic hazard assessment for the Caucasus test area

    Directory of Open Access Journals (Sweden)

    V. Trifonov

    1999-06-01

    Full Text Available The GSHAP CAUCAS test area was established under the INTAS Ct.94-1644 (Test Area for sismic Hazard Assessment in the Caucasus and NATO ARW Ct.95-1521 (Historical and Prehistorical Earthquakes in the Caucasus, with the initial support of IASPEI, UNESCO and ILP. The high tectonic interest and seismicity rate of the whole area, the availability of abundant multi-disciplinary data and the long established tradition in hazard assessment provide a unique opportunity to test different methodologies in a common test area and attempt to establish some consensus in the scientific community. Starting from the same input data (historical and instrumental seismic catalogue, lineament and homogeneous seismic source models six independent approaches to seismic hazard assessment have been used, ranging from pure historical deterministic to seismotectonic probabilistic and areal assessment methodologies. The results are here compared.

  5. Seismic analysis of liquid storage container in nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhengming [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China)]. E-mail: zhzminet@mail.tsinghua.edu.cn; He Shuyan [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Xu Ming [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China)

    2007-07-15

    Seismic analysis of liquid storage containers is always difficult in the seismic design of nuclear reactor equipment. The main reason is that the liquid will generate significant seismic loads under earthquake. These dynamic liquid loads usually form the main source of the stresses in the container. For this kind of structure-fluid coupling problem, some simplified theoretical methods were usually used previously. But this cannot satisfy the requirements of engineering design. The Finite Element Method, which is now full developed and very useful for the structural analysis, is still not mature for the structure-fluid coupling problem. This paper introduces a method suitable for engineering mechanical analysis. Combining theoretical analysis of the dynamic liquid loads and finite element analysis of the structure together, this method can give practical solutions in the seismic design of liquid storage containers.

  6. Modeling the Excitation of Seismic Waves by the Joplin Tornado

    Science.gov (United States)

    Valovcin, Anne; Tanimoto, Toshiro

    2017-10-01

    Tornadoes generate seismic signals when they contact the ground. Here we examine the signals excited by the Joplin tornado, which passed within 2 km of a station in the Earthscope Transportable Array. We model the tornado-generated vertical seismic signal at low frequencies (0.01-0.03 Hz) and solve for the strength of the seismic source. The resulting source amplitude is largest when the tornado was reported to be strongest (EF 4-5), and the amplitude is smallest when the tornado was weak (EF 0-2). A further understanding of the relationship between source amplitude and tornado intensity could open up new ways to study tornadoes from the ground.

  7. The Algerian Seismic Network: Performance from data quality analysis

    Science.gov (United States)

    Yelles, Abdelkarim; Allili, Toufik; Alili, Azouaou

    2013-04-01

    Seismic monitoring in Algeria has seen a great change after the Boumerdes earthquake of May 21st, 2003. Indeed the installation of a New Digital seismic network (ADSN) upgrade drastically the previous analog telemetry network. During the last four years, the number of stations in operation has greatly increased to 66 stations with 15 Broad Band, 02 Very Broad band, 47 Short period and 21 accelerometers connected in real time using various mode of transmission ( VSAT, ADSL, GSM, ...) and managed by Antelope software. The spatial distribution of these stations covers most of northern Algeria from east to west. Since the operation of the network, significant number of local, regional and tele-seismic events was located by the automatic processing, revised and archived in databases. This new set of data is characterized by the accuracy of the automatic location of local seismicity and the ability to determine its focal mechanisms. Periodically, data recorded including earthquakes, calibration pulse and cultural noise are checked using PSD (Power Spectral Density) analysis to determine the noise level. ADSN Broadband stations data quality is controlled in quasi real time using the "PQLX" software by computing PDFs and PSDs of the recordings. Some other tools and programs allow the monitoring and the maintenance of the entire electronic system for example to check the power state of the system, the mass position of the sensors and the environment conditions (Temperature, Humidity, Air Pressure) inside the vaults. The new design of the network allows management of many aspects of real time seismology: seismic monitoring, rapid determination of earthquake, message alert, moment tensor estimation, seismic source determination, shakemaps calculation, etc. The international standards permit to contribute in regional seismic monitoring and the Mediterranean warning system. The next two years with the acquisition of new seismic equipment to reach 50 new BB stations led to

  8. Toward Building a New Seismic Hazard Model for Mainland China

    Science.gov (United States)

    Rong, Y.; Xu, X.; Chen, G.; Cheng, J.; Magistrale, H.; Shen, Z.

    2015-12-01

    At present, the only publicly available seismic hazard model for mainland China was generated by Global Seismic Hazard Assessment Program in 1999. We are building a new seismic hazard model by integrating historical earthquake catalogs, geological faults, geodetic GPS data, and geology maps. To build the model, we construct an Mw-based homogeneous historical earthquake catalog spanning from 780 B.C. to present, create fault models from active fault data using the methodology recommended by Global Earthquake Model (GEM), and derive a strain rate map based on the most complete GPS measurements and a new strain derivation algorithm. We divide China and the surrounding regions into about 20 large seismic source zones based on seismotectonics. For each zone, we use the tapered Gutenberg-Richter (TGR) relationship to model the seismicity rates. We estimate the TGR a- and b-values from the historical earthquake data, and constrain corner magnitude using the seismic moment rate derived from the strain rate. From the TGR distributions, 10,000 to 100,000 years of synthetic earthquakes are simulated. Then, we distribute small and medium earthquakes according to locations and magnitudes of historical earthquakes. Some large earthquakes are distributed on active faults based on characteristics of the faults, including slip rate, fault length and width, and paleoseismic data, and the rest to the background based on the distributions of historical earthquakes and strain rate. We evaluate available ground motion prediction equations (GMPE) by comparison to observed ground motions. To apply appropriate GMPEs, we divide the region into active and stable tectonics. The seismic hazard will be calculated using the OpenQuake software developed by GEM. To account for site amplifications, we construct a site condition map based on geology maps. The resulting new seismic hazard map can be used for seismic risk analysis and management, and business and land-use planning.

  9. Influence of the Radial Clearance of a Squeeze Film Damper on the Vibratory Behavior of a Single Spool Gas Turbine Designed for Unmanned Aerial Vehicle Applications

    Directory of Open Access Journals (Sweden)

    Geraldo Creci

    2017-01-01

    Full Text Available This study presents a numerical investigation using the finite element method on the vibratory behavior of a single spool gas turbine designed for unmanned aerial vehicle applications. The shaft of the rotor-bearing system is supported on a front bearing composed of a deep groove ball bearing with a vibration absorber element and a rear squeeze film damper bearing. Three radial clearances for the squeeze film damper were analyzed to determine the best geometric configuration for the rear bearing, considering the rotordynamic performance of the entire system. Whirl speeds and unbalanced system responses were carefully evaluated to determine the best radial clearance for the squeeze film damper. After defining the best radial clearance, a transient analysis was performed to simulate the transition of the system through resonance, and a spectral map is presented to illustrate the vibratory behavior of the system considering the influence of all related important frequencies. The rotordynamic behavior of the system is predicted, and vibration problems are avoided. Its mechanical drawings were released to manufacturing, and the first prototype is in the experimental test phase, thus indicating that the numerical results presented in this study are consistent.

  10. Obtention of hydroxyapatite submicrometric of bovine origin by vibratory grinding for rapid prototyping; Obtencao de hidroxiapatita submicrometrica de origem bovina por moagem vibratoria visando prototipagem rapida

    Energy Technology Data Exchange (ETDEWEB)

    Meira, C.R.; Purquerio, B.M.; Fortulan, C.A., E-mail: camilameira@sc.usp.br [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Escola de Engenharia; Braga, F.J.C. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Submicron bovine hydroxyapatite was obtained for rapid prototyping. Hydroxyapatite structure originated from bovine mineral bone has great importance among the biomaterials and biocompatibility due to its great similarity with the human bone structure. This study aims to obtain powder for manufacture by rapid prototyping of scaffolds. This technique manufacture requires highly reactive powders to compensate for the absence of pressure forming. Hydroxyapatite was milled in a ball mill and vibratory mill, and analyzed for their average equivalent spherical diameter and surface area. Test specimens were isostatically pressed at 100 MPa and machined into cylindrical test specimens. These specimens were sintered at several temperatures to determine the optimal sintering temperature based on densification and chemistry stability. In grinding ball mill was obtained particles of equivalent diameter of 0.74 micron in vibratory mill of 0.46 micrometers. An average flexural strength of 100 MPa and 99,8% of real density was attained for the sample sintered at 1300 deg C/2h, signaling potential for use in rapid prototyping. (author)

  11. Observations on Intraplate Seismicity in Central Fennoscandia

    Science.gov (United States)

    Korja, Annakaisa; Uski, Marja; Lund, Bjorn; Högdahl, Karin; Grigull, Susanne; Nironen, Mikko

    2016-04-01

    the rebound stress is the main source for triggering seismicity in Fennoscandia today. However, in late- and post-glacial times, glacially-induced isostatic rebound was probably much more important for the generation of earthquakes.

  12. Gasgeochemical indicators seismic activity

    Science.gov (United States)

    Obzhirov, Anatoly

    2017-10-01

    Laboratory of Gasgeochemistry of POI FEB RAS is studying gas distribution in lithosphere, hydrosphere and atmosphere from 1977 years. Method consist is sampling from its in expedition, take gas from samples of sediment, water and atmosphere to use method degassing and analysis gas in chromatograph, to measure CH4, C2-C4, O2, N2, H2, He and some time Rn. Gas is using like indicators to search oil-gas deposits, gas hydrate, mapping zones faults, to determine seismic activity, to calculate green house gas (CH4, CO2). The next geological, geophysics and hydro-acoustics characteristics assist which help to explain to form methane bubbles fluxes and gas hydrate in the Okhotsk Sea. The methane fluxes are mostly located in the zones faults and it increase in period seismic activity.

  13. Excitation Mechanisms for Jovian Seismic Modes

    Science.gov (United States)

    Markham, Stephen; Stevenson, David J.

    2017-10-01

    Recent (2011) results from the Nice Observatory indicate the existence of global seismic modes on Jupiter in the frequency range between 0.7 and 1.5mHz with amplitudes of tens of cm/s. Currently, the driving force behind these modes is a mystery; the measured amplitudes were much larger than anticipated based on theory analogous to helioseismology (that is, turbulent convection as a source of stochastic excitation). One of the most promising hypotheses is that these modes are driven by Jovian storms. This work constructs a framework to analytically model the expected equilibrium normal mode amplitudes arising from convective columns in storms. We also place rough constraints of Jupiter's seismic modal quality factor. Using this model, neither meteor strikes, turbulent convection, nor water storms can feasibly excite the order of magnitude of observed amplitudes. Next we speculate about the potential role of rock storms deeper in Jupiter's atmosphere, because the rock storms' expected energy scales make them promising candidates to be the chief source of excitation for Jovian seismic modes, based on simple scaling arguments. Finally we suggest a predicted power spectrum for frequencies which have not yet been observed based on our findings, and supply some commentary on potential applications to Juno, Saturn, and future missions to Uranus and Neptune.

  14. Probing the internal structure of the asteriod Didymoon with a passive seismic investigation

    Science.gov (United States)

    Murdoch, N.; Hempel, S.; Pou, L.; Cadu, A.; Garcia, R. F.; Mimoun, D.; Margerin, L.; Karatekin, O.

    2017-09-01

    Understanding the internal structure of an asteroid has important implications for interpreting its evolutionary history, for understanding its continuing geological evolution, and also for asteroid deflection and in-situ space resource utilisation. Given the strong evidence that asteroids are seismically active, an in-situ passive seismic experiment could provide information about the asteroid surface and interior properties. Here, we discuss the natural seismic activity that may be present on Didymoon, the secondary component of asteroid (65803) Didymos. Our analysis of the tidal stresses in Didymoon shows that tidal quakes are likely to occur if the secondary has an eccentric orbit. Failure occurs most easily at the asteroid poles and close to the surface for both homogeneous and layered internal structures. Simulations of seismic wave propagation in Didymoon show that the seismic moment of even small meteoroid impacts can generate clearly observable body and surface waves if the asteroid's internal structure is homogeneous. The presence of a regolith layer over a consolidated core can result in the seismic energy becoming trapped in the regolith due to the strong impedance contrast at the regolith-core boundary. The inclusion of macro-porosity (voids) further complexifies the wavefield due to increased scattering. The most prominent seismic waves are always found to be those traveling along the surface of the asteroid and those focusing in the antipodal point of the seismic source. We find also that the waveforms and ground acceleration spectra allow discrimination between the different internal structure models. Although the science return of a passive seismic experiment would be enhanced by having multiple seismic stations, one single seismic station can already vastly improve our knowledge about the seismic environment and sub-surface structure of an asteroid. We describe several seismic measurement techniques that could be applied in order to study the

  15. Establishing seismic design criteria to achieve an acceptable seismic margin

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, R.P. [RPK Structural Mechanics Consulting, Inc., Yorba Linda, CA (United States)

    1997-01-01

    In order to develop a risk based seismic design criteria the following four issues must be addressed: (1) What target annual probability of seismic induced unacceptable performance is acceptable? (2). What minimum seismic margin is acceptable? (3) Given the decisions made under Issues 1 and 2, at what annual frequency of exceedance should the Safe Shutdown Earthquake ground motion be defined? (4) What seismic design criteria should be established to reasonably achieve the seismic margin defined under Issue 2? The first issue is purely a policy decision and is not addressed in this paper. Each of the other three issues are addressed. Issues 2 and 3 are integrally tied together so that a very large number of possible combinations of responses to these two issues can be used to achieve the target goal defined under Issue 1. Section 2 lays out a combined approach to these two issues and presents three potentially attractive combined resolutions of these two issues which reasonably achieves the target goal. The remainder of the paper discusses an approach which can be used to develop seismic design criteria aimed at achieving the desired seismic margin defined in resolution of Issue 2. Suggestions for revising existing seismic design criteria to more consistently achieve the desired seismic margin are presented.

  16. The Global Detection Capability of the IMS Seismic Network in 2013 Inferred from Ambient Seismic Noise Measurements

    Science.gov (United States)

    Gaebler, P. J.; Ceranna, L.

    2016-12-01

    All nuclear explosions - on the Earth's surface, underground, underwater or in the atmosphere - are banned by the Comprehensive Nuclear-Test-Ban Treaty (CTBT). As part of this treaty, a verification regime was put into place to detect, locate and characterize nuclear explosion testings at any time, by anyone and everywhere on the Earth. The International Monitoring System (IMS) plays a key role in the verification regime of the CTBT. Out of the different monitoring techniques used in the IMS, the seismic waveform approach is the most effective technology for monitoring nuclear underground testing and to identify and characterize potential nuclear events. This study introduces a method of seismic threshold monitoring to assess an upper magnitude limit of a potential seismic event in a certain given geographical region. The method is based on ambient seismic background noise measurements at the individual IMS seismic stations as well as on global distance correction terms for body wave magnitudes, which are calculated using the seismic reflectivity method. From our investigations we conclude that a global detection threshold of around mb 4.0 can be achieved using only stations from the primary seismic network, a clear latitudinal dependence for the detection thresholdcan be observed between northern and southern hemisphere. Including the seismic stations being part of the auxiliary seismic IMS network results in a slight improvement of global detection capability. However, including wave arrivals from distances greater than 120 degrees, mainly PKP-wave arrivals, leads to a significant improvement in average global detection capability. In special this leads to an improvement of the detection threshold on the southern hemisphere. We further investigate the dependence of the detection capability on spatial (latitude and longitude) and temporal (time) parameters, as well as on parameters such as source type and percentage of operational IMS stations.

  17. Harmonized Probabilistic Seismic Hazard Assessment in Europe: Earthquake Geology Applied

    Science.gov (United States)

    Woessner, J.; Danciu, L.; Giardini, D.; Share Consortium

    2012-04-01

    Probabilistic seismic hazard assessment (PSHA) aims to characterize the best available knowledge on seismic hazard of a study area, ideally taking into account all sources of uncertainty. Results from PSHAs form the baseline for informed decision-making and provide essential input to each risk assessment application. SHARE is an EC-FP7 funded project to create a testable time-independent community-based hazard model for the Euro-Mediterranean region. SHARE scientists are creating a model framework and infrastructure for a harmonized PSHA. The results will serve as reference for the Eurocode 8 application and are envisioned to provide homogeneous input for state-of-the art seismic safety assessment for critical industry. Harmonizing hazard is pursued on the input data level and the model building procedure across borders and tectonic features of the European-Mediterranean region. An updated earthquake catalog, a harmonized database of seismogenic sources together with adjusted ground motion prediction equations (GMPEs) form the bases for a borderless assessment. We require transparent and reproducible strategies to estimate parameter values and their uncertainties within the source model assessment and the contributions of the GMPEs. The SHARE model accounts for uncertainties via a logic tree. Epistemic uncertainties within the seismic source-model are represented by four source model options including area sources, fault sources and kernel-smoothing approaches, aleatory uncertainties for activity rates and maximum magnitudes. Epistemic uncertainties for predicted ground motions are considered by multiple GMPEs as a function of tectonic settings and treated as being correlated. For practical implementation, epistemic uncertainties in the source model (i.e. dip and strike angles) are treated as aleatory, and a mean seismicity model is considered. The final results contain the full distribution of ground motion variability. This contribution will feature preliminary

  18. First level seismic microzonation map of Chennai city – a GIS approach

    Directory of Open Access Journals (Sweden)

    G. P. Ganapathy

    2011-02-01

    Full Text Available Chennai city is the fourth largest metropolis in India, is the focus of economic, social and cultural development and it is the capital of the State of Tamil Nadu. The city has a multi-dimensional growth in development of its infrastructures and population. The area of Chennai has experienced moderate earthquakes in the historical past. Also the Bureau of Indian Standard upgraded the seismic status of Chennai from Low Seismic Hazard (Zone II to Moderate Seismic Hazard (Zone III–(BIS: 1893 (2001. In this connection, a first level seismic microzonation map of Chennai city has been produced with a GIS platform using the themes, viz, Peak Ground Acceleration (PGA, Shear wave velocity at 3 m, Geology, Ground water fluctuation and bed rock depth. The near potential seismic sources were identified from the remote-sensing study and seismo-tectonic details from published literatures. The peak ground acceleration for these seismic sources were estimated based on the attenuation relationship and the maximum PGA for Chennai is 0.176 g. The groundwater fluctuation of the city varies from 0–4 m below ground level. The depth to bedrock configuration shows trough and ridges in the bedrock topography all over the city. The seismic microzonation analysis involved grid datasets (the discrete datasets from different themes were converted to grids to compute the final seismic hazard grid through integration and weightage analysis of the source themes. The Chennai city has been classified into three broad zones, viz, High, Moderate and Low Seismic Hazard. The High seismic Hazard concentrated in a few places in the western central part of the city. The moderate hazard areas are oriented in NW-SE direction in the Western part. The southern and eastern part will have low seismic hazard. The result of the study may be used as first-hand information in selecting the appropriate earthquake resistant features in designing the forthcoming new buildings against seismic

  19. Seismic survey considerations in glaciology

    OpenAIRE

    Hofstede, Coen

    2015-01-01

    Seismic surveying of glaciers give both englacial and subglacial physical information and is as such an important tool in glaciology. In comparison with the collection of radar data, mainly performed from airborne platforms, seismic data acquisition is a time consuming process practiced in small survey areas and used less frequent. Over the last six years, AWI developed an effective strategy to collect seismic data on glaciers, ice sheets and ice shelves, at a high production rate with a smal...

  20. Perseids permanent seismic downhole system

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    PERSEIDS{sup TM} describes a permanent seismic downhole system. In that system, geo-phones are either cemented or mounted on tubing and coupled to the casing through a bow-string. Perseids{sup TM} is ideal for both passive and active seismic monitoring, to visualize bypass areas, gas cap and aquifer expansion. It can be combined with {mu}SICS{sup TM} software to record, process and interpret micro-seismic activity.

  1. Probabilistic Seismic Hazard Assessment for Northeast India Region

    Science.gov (United States)

    Das, Ranjit; Sharma, M. L.; Wason, H. R.

    2016-08-01

    Northeast India bounded by latitudes 20°-30°N and longitudes 87°-98°E is one of the most seismically active areas in the world. This region has experienced several moderate-to-large-sized earthquakes, including the 12 June, 1897 Shillong earthquake ( M w 8.1) and the 15 August, 1950 Assam earthquake ( M w 8.7) which caused loss of human lives and significant damages to buildings highlighting the importance of seismic hazard assessment for the region. Probabilistic seismic hazard assessment of the region has been carried out using a unified moment magnitude catalog prepared by an improved General Orthogonal Regression methodology (Geophys J Int, 190:1091-1096, 2012; Probabilistic seismic hazard assessment of Northeast India region, Ph.D. Thesis, Department of Earthquake Engineering, IIT Roorkee, Roorkee, 2013) with events compiled from various databases (ISC, NEIC,GCMT, IMD) and other available catalogs. The study area has been subdivided into nine seismogenic source zones to account for local variation in tectonics and seismicity characteristics. The seismicity parameters are estimated for each of these source zones, which are input variables into seismic hazard estimation of a region. The seismic hazard analysis of the study region has been performed by dividing the area into grids of size 0.1° × 0.1°. Peak ground acceleration (PGA) and spectral acceleration ( S a) values (for periods of 0.2 and 1 s) have been evaluated at bedrock level corresponding to probability of exceedance (PE) of 50, 20, 10, 2 and 0.5 % in 50 years. These exceedance values correspond to return periods of 100, 225, 475, 2475, and 10,000 years, respectively. The seismic hazard maps have been prepared at the bedrock level, and it is observed that the seismic hazard estimates show a significant local variation in contrast to the uniform hazard value suggested by the Indian standard seismic code [Indian standard, criteria for earthquake-resistant design of structures, fifth edition, Part

  2. Seismic Waveform Inversion : Bump functional, parameterization analysis and imaging ahead of a tunnel-boring machine

    NARCIS (Netherlands)

    Pisupati, P.B.

    2017-01-01

    During a seismic experiment, mechanical waves are usually generated by various manmade sources. These waves propagate in the subsurface and are recorded at receivers. Modern seismic exploration methods analyze them to infer the mechanical properties of the subsurface; this is commonly referred as

  3. Response of a panel building to mining induced seismicity in Karvina

    Directory of Open Access Journals (Sweden)

    Viktor Kanický

    2009-09-01

    Full Text Available A dynamic behaviour of technological structures and buildings under a non-stationary dynamic loading is investigatedby technical seismicity. The solution of this problem is based on field seismic measurements using a specific source of technicalseismicity induced by the mining activity in the area under study (Karviná region in the Czech Republic. Finite element models areprepared for computer analyses of seismic responses of measured structures. The twelve-storey panel residential building was selectedfor the seismic analysis as a representative structure.

  4. Calving seismicity from iceberg-sea surface interactions

    Science.gov (United States)

    Bartholomaus, T.C.; Larsen, C.F.; O'Neel, S.; West, M.E.

    2012-01-01

    Iceberg calving is known to release substantial seismic energy, but little is known about the specific mechanisms that produce calving icequakes. At Yahtse Glacier, a tidewater glacier on the Gulf of Alaska, we draw upon a local network of seismometers and focus on 80 hours of concurrent, direct observation of the terminus to show that calving is the dominant source of seismicity. To elucidate seismogenic mechanisms, we synchronized video and seismograms to reveal that the majority of seismic energy is produced during iceberg interactions with the sea surface. Icequake peak amplitudes coincide with the emergence of high velocity jets of water and ice from the fjord after the complete submergence of falling icebergs below sea level. These icequakes have dominant frequencies between 1 and 3 Hz. Detachment of an iceberg from the terminus produces comparatively weak seismic waves at frequencies between 5 and 20 Hz. Our observations allow us to suggest that the most powerful sources of calving icequakes at Yahtse Glacier include iceberg-sea surface impact, deceleration under the influence of drag and buoyancy, and cavitation. Numerical simulations of seismogenesis during iceberg-sea surface interact