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Sample records for instrumentally recorded earthquake

  1. Probabilistic Seismic Hazard Assessment for Himalayan-Tibetan Region from Historical and Instrumental Earthquake Catalogs

    Science.gov (United States)

    Rahman, M. Moklesur; Bai, Ling; Khan, Nangyal Ghani; Li, Guohui

    2018-02-01

    The Himalayan-Tibetan region has a long history of devastating earthquakes with wide-spread casualties and socio-economic damages. Here, we conduct the probabilistic seismic hazard analysis by incorporating the incomplete historical earthquake records along with the instrumental earthquake catalogs for the Himalayan-Tibetan region. Historical earthquake records back to more than 1000 years ago and an updated, homogenized and declustered instrumental earthquake catalog since 1906 are utilized. The essential seismicity parameters, namely, the mean seismicity rate γ, the Gutenberg-Richter b value, and the maximum expected magnitude M max are estimated using the maximum likelihood algorithm assuming the incompleteness of the catalog. To compute the hazard value, three seismogenic source models (smoothed gridded, linear, and areal sources) and two sets of ground motion prediction equations are combined by means of a logic tree on accounting the epistemic uncertainties. The peak ground acceleration (PGA) and spectral acceleration (SA) at 0.2 and 1.0 s are predicted for 2 and 10% probabilities of exceedance over 50 years assuming bedrock condition. The resulting PGA and SA maps show a significant spatio-temporal variation in the hazard values. In general, hazard value is found to be much higher than the previous studies for regions, where great earthquakes have actually occurred. The use of the historical and instrumental earthquake catalogs in combination of multiple seismogenic source models provides better seismic hazard constraints for the Himalayan-Tibetan region.

  2. Design spectrums based on earthquakes recorded at tarbela

    International Nuclear Information System (INIS)

    Rizwan, M.; Ilyas, M.; Masood, A.

    2008-01-01

    First Seismological Network in Pakistan was setup in early 1969 at Tarbela, which is the location of largest water reservoir of the country. The network consisted of Analog Accelerograms and Seismographs. Since the installation many seismic events of different magnitudes occurred and were recorded by the installed instruments. The analog form of recorded time histories has been digitized and data of twelve earthquakes, irrespective of the type of soil, has been used to derive elastic design spectrums for Tarbela, Pakistan. The PGA scaling factors, based on the risk analysis studies carried out for the region, for each component are also given. The design spectrums suggested will be very useful for carrying out new construction in the region and its surroundings. The digitized data of time histories will be useful for seismic response analysis of structures and seismic risk analysis of the region. (author)

  3. The Landers earthquake; preliminary instrumental results

    Science.gov (United States)

    Jones, L.; Mori, J.; Hauksson, E.

    1992-01-01

    Early on the morning of June 28, 1992, millions of people in southern California were awakened by the largest earthquake to occur in the western United States in the past 40 yrs. At 4:58 a.m PDT (local time), faulting associated with the magnitude 7.3 earthquake broke through to earth's surface near the town of Landers, California. the surface rupture then propagated 70km (45 mi) to the north and northwest along a band of faults passing through the middle of the Mojave Desert. Fortunately, the strongest shaking occurred in uninhabited regions of the Mojave Desert. Still one child was killed in Yucca Valley, and about 400 people were injured in the surrounding area. the desert communities of Landers, Yucca Valley, and Joshua Tree in San Bernardino Country suffered considerable damage to buildings and roads. Damage to water and power lines caused problems in many areas. 

  4. Earthquake Recurrence and the Resolution Potential of Tectono‐Geomorphic Records

    KAUST Repository

    Zielke, Olaf

    2018-04-17

    A long‐standing debate in active tectonics addresses how slip is accumulated through space and time along a given fault or fault section. This debate is in part still ongoing because of the lack of sufficiently long instrumental data that may constrain the recurrence characteristics of surface‐rupturing earthquakes along individual faults. Geomorphic and stratigraphic records are used instead to constrain this behavior. Although geomorphic data frequently indicate slip accumulation via quasicharacteristic same‐size offset increments, stratigraphic data indicate that earthquake timing observes a quasirandom distribution. Assuming that both observations are valid within their respective frameworks, I want to address here which recurrence model is able to reproduce this seemingly contradictory behavior. I further want to address how aleatory offset variability and epistemic measurement uncertainty affect our ability to resolve single‐earthquake surface slip and along‐fault slip‐accumulation patterns. I use a statistical model that samples probability density functions (PDFs) for geomorphic marker formation (storm events), marker displacement (surface‐rupturing earthquakes), and offset measurement, generating tectono‐geomorphic catalogs to investigate which PDF combination consistently reproduces the above‐mentioned field observations. Doing so, I find that neither a purely characteristic earthquake (CE) nor a Gutenberg–Richter (GR) earthquake recurrence model is able to consistently reproduce those field observations. A combination of both however, with moderate‐size earthquakes following the GR model and large earthquakes following the CE model, is able to reproduce quasirandom earthquake recurrence times while simultaneously generating quasicharacteristic geomorphic offset increments. Along‐fault slip accumulation is dominated by, but not exclusively linked to, the occurrence of similar‐size large earthquakes. Further, the resolution

  5. Reading a 400,000-year record of earthquake frequency for an intraplate fault.

    Science.gov (United States)

    Williams, Randolph T; Goodwin, Laurel B; Sharp, Warren D; Mozley, Peter S

    2017-05-09

    Our understanding of the frequency of large earthquakes at timescales longer than instrumental and historical records is based mostly on paleoseismic studies of fast-moving plate-boundary faults. Similar study of intraplate faults has been limited until now, because intraplate earthquake recurrence intervals are generally long (10s to 100s of thousands of years) relative to conventional paleoseismic records determined by trenching. Long-term variations in the earthquake recurrence intervals of intraplate faults therefore are poorly understood. Longer paleoseismic records for intraplate faults are required both to better quantify their earthquake recurrence intervals and to test competing models of earthquake frequency (e.g., time-dependent, time-independent, and clustered). We present the results of U-Th dating of calcite veins in the Loma Blanca normal fault zone, Rio Grande rift, New Mexico, United States, that constrain earthquake recurrence intervals over much of the past ∼550 ka-the longest direct record of seismic frequency documented for any fault to date. The 13 distinct seismic events delineated by this effort demonstrate that for >400 ka, the Loma Blanca fault produced periodic large earthquakes, consistent with a time-dependent model of earthquake recurrence. However, this time-dependent series was interrupted by a cluster of earthquakes at ∼430 ka. The carbon isotope composition of calcite formed during this seismic cluster records rapid degassing of CO 2 , suggesting an interval of anomalous fluid source. In concert with U-Th dates recording decreased recurrence intervals, we infer seismicity during this interval records fault-valve behavior. These data provide insight into the long-term seismic behavior of the Loma Blanca fault and, by inference, other intraplate faults.

  6. Reading a 400,000-year record of earthquake frequency for an intraplate fault

    Science.gov (United States)

    Williams, Randolph T.; Goodwin, Laurel B.; Sharp, Warren D.; Mozley, Peter S.

    2017-05-01

    Our understanding of the frequency of large earthquakes at timescales longer than instrumental and historical records is based mostly on paleoseismic studies of fast-moving plate-boundary faults. Similar study of intraplate faults has been limited until now, because intraplate earthquake recurrence intervals are generally long (10s to 100s of thousands of years) relative to conventional paleoseismic records determined by trenching. Long-term variations in the earthquake recurrence intervals of intraplate faults therefore are poorly understood. Longer paleoseismic records for intraplate faults are required both to better quantify their earthquake recurrence intervals and to test competing models of earthquake frequency (e.g., time-dependent, time-independent, and clustered). We present the results of U-Th dating of calcite veins in the Loma Blanca normal fault zone, Rio Grande rift, New Mexico, United States, that constrain earthquake recurrence intervals over much of the past ˜550 ka—the longest direct record of seismic frequency documented for any fault to date. The 13 distinct seismic events delineated by this effort demonstrate that for >400 ka, the Loma Blanca fault produced periodic large earthquakes, consistent with a time-dependent model of earthquake recurrence. However, this time-dependent series was interrupted by a cluster of earthquakes at ˜430 ka. The carbon isotope composition of calcite formed during this seismic cluster records rapid degassing of CO2, suggesting an interval of anomalous fluid source. In concert with U-Th dates recording decreased recurrence intervals, we infer seismicity during this interval records fault-valve behavior. These data provide insight into the long-term seismic behavior of the Loma Blanca fault and, by inference, other intraplate faults.

  7. Extending the ISC-GEM Global Earthquake Instrumental Catalogue

    Science.gov (United States)

    Di Giacomo, Domenico; Engdhal, Bob; Storchak, Dmitry; Villaseñor, Antonio; Harris, James

    2015-04-01

    After a 27-month project funded by the GEM Foundation (www.globalquakemodel.org), in January 2013 we released the ISC-GEM Global Instrumental Earthquake Catalogue (1900 2009) (www.isc.ac.uk/iscgem/index.php) as a special product to use for seismic hazard studies. The new catalogue was necessary as improved seismic hazard studies necessitate that earthquake catalogues are homogeneous (to the largest extent possible) over time in their fundamental parameters, such as location and magnitude. Due to time and resource limitation, the ISC-GEM catalogue (1900-2009) included earthquakes selected according to the following time-variable cut-off magnitudes: Ms=7.5 for earthquakes occurring before 1918; Ms=6.25 between 1918 and 1963; and Ms=5.5 from 1964 onwards. Because of the importance of having a reliable seismic input for seismic hazard studies, funding from GEM and two commercial companies in the US and UK allowed us to start working on the extension of the ISC-GEM catalogue both for earthquakes that occurred beyond 2009 and for earthquakes listed in the International Seismological Summary (ISS) which fell below the cut-off magnitude of 6.25. This extension is part of a four-year program that aims at including in the ISC-GEM catalogue large global earthquakes that occurred before the beginning of the ISC Bulletin in 1964. In this contribution we present the updated ISC GEM catalogue, which will include over 1000 more earthquakes that occurred in 2010 2011 and several hundreds more between 1950 and 1959. The catalogue extension between 1935 and 1949 is currently underway. The extension of the ISC-GEM catalogue will also be helpful for regional cross border seismic hazard studies as the ISC-GEM catalogue should be used as basis for cross-checking the consistency in location and magnitude of those earthquakes listed both in the ISC GEM global catalogue and regional catalogues.

  8. Update of Earthquake Strong-Motion Instrumentation at Lawrence Livermore National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Murray, Robert C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2013-09-01

    Following the January 1980 earthquake that was felt at Lawrence Livermore National Laboratory (LLNL), a network of strong-motion accelerographs was installed at LLNL. Prior to the 1980 earthquake, there were no accelerographs installed. The ground motion from the 1980 earthquake was estimated from USGS instruments around the Laboratory to be between 0.2 – 0.3 g horizontal peak ground acceleration. These instruments were located at the Veterans Hospital, 5 miles southwest of LLNL, and in San Ramon, about 12 miles west of LLNL. In 2011, the Department of Energy (DOE) requested to know the status of our seismic instruments. We conducted a survey of our instrumentation systems and responded to DOE in a letter. During this survey, it was found that the recorders in Buildings 111 and 332 were not operational. The instruments on Nova had been removed, and only three of the 10 NIF instruments installed in 2005 were operational (two were damaged and five had been removed from operation at the request of the program). After the survey, it was clear that the site seismic instrumentation had degraded substantially and would benefit from an overhaul and more attention to ongoing maintenance. LLNL management decided to update the LLNL seismic instrumentation system. The updated system is documented in this report.

  9. Time series modelling of the Kobe-Osaka earthquake recordings

    Directory of Open Access Journals (Sweden)

    N. Singh

    2002-01-01

    generated by an earthquake. With a view of comparing these two types of waveforms, Singh (1992 developed a technique for identifying a model in time domain. Fortunately this technique has been found useful in modelling the recordings of the killer earthquake occurred in the Kobe-Osaka region of Japan at 5.46 am on 17 January, 1995. The aim of the present study is to show how well the method for identifying a model (developed by Singh (1992 can be used for describing the vibrations of the above mentioned earthquake recorded at Charters Towers in Queensland, Australia.

  10. An instrumental earthquake catalogue for northeastern Italy since 1900

    International Nuclear Information System (INIS)

    Margottini, C.; Martini, G.; Slejko, D.

    1991-01-01

    An earthquake catalogue of instrumental data for northeastern Italy since 1900 is presented. The different types of magnitude, which are the main parameters of the present study, have been evaluated so as to be as homogeneous as possible. Comparisons of the different magnitude values show linear dependence, at least in the medium magnitude range represented by the available data set. Correlations between the magnitude most significant for this region and chosen macroseismic data indicate a methodology for assessing the macroseismic magnitude of historical earthquakes which seems to be stable. (author)

  11. Instrument Records And Plays Back Acceleration Signals

    Science.gov (United States)

    Bozeman, Richard J.

    1994-01-01

    Small, battery-powered, hand-held instrument feeds power to accelerometer and records time-varying component of output for 15 seconds in analog form. No power needed to maintain content of memory; memory chip removed after recording and stored indefinitely. Recorded signal plays back at any time up to several years later. Principal advantages: compactness, portability, and low cost.

  12. Magnitude Estimation for Large Earthquakes from Borehole Recordings

    Science.gov (United States)

    Eshaghi, A.; Tiampo, K. F.; Ghofrani, H.; Atkinson, G.

    2012-12-01

    We present a simple and fast method for magnitude determination technique for earthquake and tsunami early warning systems based on strong ground motion prediction equations (GMPEs) in Japan. This method incorporates borehole strong motion records provided by the Kiban Kyoshin network (KiK-net) stations. We analyzed strong ground motion data from large magnitude earthquakes (5.0 ≤ M ≤ 8.1) with focal depths < 50 km and epicentral distances of up to 400 km from 1996 to 2010. Using both peak ground acceleration (PGA) and peak ground velocity (PGV) we derived GMPEs in Japan. These GMPEs are used as the basis for regional magnitude determination. Predicted magnitudes from PGA values (Mpga) and predicted magnitudes from PGV values (Mpgv) were defined. Mpga and Mpgv strongly correlate with the moment magnitude of the event, provided sufficient records for each event are available. The results show that Mpgv has a smaller standard deviation in comparison to Mpga when compared with the estimated magnitudes and provides a more accurate early assessment of earthquake magnitude. We test this new method to estimate the magnitude of the 2011 Tohoku earthquake and we present the results of this estimation. PGA and PGV from borehole recordings allow us to estimate the magnitude of this event 156 s and 105 s after the earthquake onset, respectively. We demonstrate that the incorporation of borehole strong ground-motion records immediately available after the occurrence of large earthquakes significantly increases the accuracy of earthquake magnitude estimation and the associated improvement in earthquake and tsunami early warning systems performance. Moment magnitude versus predicted magnitude (Mpga and Mpgv).

  13. Artificial earthquake record generation using cascade neural network

    Directory of Open Access Journals (Sweden)

    Bani-Hani Khaldoon A.

    2017-01-01

    Full Text Available This paper presents the results of using artificial neural networks (ANN in an inverse mapping problem for earthquake accelerograms generation. This study comprises of two parts: 1-D site response analysis; performed for Dubai Emirate at UAE, where eight earthquakes records are selected and spectral matching are performed to match Dubai response spectrum using SeismoMatch software. Site classification of Dubai soil is being considered for two classes C and D based on shear wave velocity of soil profiles. Amplifications factors are estimated to quantify Dubai soil effect. Dubai’s design response spectra are developed for site classes C & D according to International Buildings Code (IBC -2012. In the second part, ANN is employed to solve inverse mapping problem to generate time history earthquake record. Thirty earthquakes records and their design response spectrum with 5% damping are used to train two cascade forward backward neural networks (ANN1, ANN2. ANN1 is trained to map the design response spectrum to time history and ANN2 is trained to map time history records to the design response spectrum. Generalized time history earthquake records are generated using ANN1 for Dubai’s site classes C and D, and ANN2 is used to evaluate the performance of ANN1.

  14. A new reference global instrumental earthquake catalogue (1900-2009)

    Science.gov (United States)

    Di Giacomo, D.; Engdahl, B.; Bondar, I.; Storchak, D. A.; Villasenor, A.; Bormann, P.; Lee, W.; Dando, B.; Harris, J.

    2011-12-01

    For seismic hazard studies on a global and/or regional scale, accurate knowledge of the spatial distribution of seismicity, the magnitude-frequency relation and the maximum magnitudes is of fundamental importance. However, such information is normally not homogeneous (or not available) for the various seismically active regions of the Earth. To achieve the GEM objectives (www.globalquakemodel.org) of calculating and communicating earthquake risk worldwide, an improved reference global instrumental catalogue for large earthquakes spanning the entire 100+ years period of instrumental seismology is an absolute necessity. To accomplish this task, we apply the most up-to-date techniques and standard observatory practices for computing the earthquake location and magnitude. In particular, the re-location procedure benefits both from the depth determination according to Engdahl and Villaseñor (2002), and the advanced technique recently implemented at the ISC (Bondár and Storchak, 2011) to account for correlated error structure. With regard to magnitude, starting from the re-located hypocenters, the classical surface and body-wave magnitudes are determined following the new IASPEI standards and by using amplitude-period data of phases collected from historical station bulletins (up to 1970), which were not available in digital format before the beginning of this work. Finally, the catalogue will provide moment magnitude values (including uncertainty) for each seismic event via seismic moment, via surface wave magnitude or via other magnitude types using empirical relationships. References Engdahl, E.R., and A. Villaseñor (2002). Global seismicity: 1900-1999. In: International Handbook of Earthquake and Engineering Seismology, eds. W.H.K. Lee, H. Kanamori, J.C. Jennings, and C. Kisslinger, Part A, 665-690, Academic Press, San Diego. Bondár, I., and D. Storchak (2011). Improved location procedures at the International Seismological Centre, Geophys. J. Int., doi:10.1111/j

  15. Long-period pulses in broadband records of near earthquakes

    Czech Academy of Sciences Publication Activity Database

    Zahradník, J.; Plešinger, Axel

    2005-01-01

    Roč. 95, č. 5 (2005), s. 1928-1939 ISSN 0037-1106 R&D Projects: GA ČR GA205/02/0381; GA ČR GA205/03/1047 Grant - others:EC(XE) EVG3-CT-2002-80006 ( MAGMA ) Institutional research plan: CEZ:AV0Z30120515 Keywords : broadband records * near earthquakes * seismic signal Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.772, year: 2005

  16. Analysis of recorded earthquake response data at the Hualien large-scale seismic test site

    International Nuclear Information System (INIS)

    Hyun, C.H.; Tang, H.T.; Dermitzakis, S.; Esfandiari, S.

    1997-01-01

    A soil-structure interaction (SSI) experiment is being conducted in a seismically active region in Hualien, Taiwan. To obtain earthquake data for quantifying SSI effects and providing a basis to benchmark analysis methods, a 1/4-th scale cylindrical concrete containment model similar in shape to that of a nuclear power plant containment was constructed in the field where both the containment model and its surrounding soil, surface and sub-surface, are extensively instrumented to record earthquake data. In between September 1993 and May 1995, eight earthquakes with Richter magnitudes ranging from 4.2 to 6.2 were recorded. The author focuses on studying and analyzing the recorded data to provide information on the response characteristics of the Hualien soil-structure system, the SSI effects and the ground motion characteristics. An effort was also made to directly determine the site soil physical properties based on correlation analysis of the recorded data. No modeling simulations were attempted to try to analytically predict the SSI response of the soil and the structure. These will be the scope of a subsequent study

  17. Catastrophic valley fills record large Himalayan earthquakes, Pokhara, Nepal

    Science.gov (United States)

    Stolle, Amelie; Bernhardt, Anne; Schwanghart, Wolfgang; Hoelzmann, Philipp; Adhikari, Basanta R.; Fort, Monique; Korup, Oliver

    2017-12-01

    Uncertain timing and magnitudes of past mega-earthquakes continue to confound seismic risk appraisals in the Himalayas. Telltale traces of surface ruptures are rare, while fault trenches document several events at best, so that additional proxies of strong ground motion are needed to complement the paleoseismological record. We study Nepal's Pokhara basin, which has the largest and most extensively dated archive of earthquake-triggered valley fills in the Himalayas. These sediments form a 148-km2 fan that issues from the steep Seti Khola gorge in the Annapurna Massif, invading and plugging 15 tributary valleys with tens of meters of debris, and impounding several lakes. Nearly a dozen new radiocarbon ages corroborate at least three episodes of catastrophic sedimentation on the fan between ∼700 and ∼1700 AD, coinciding with great earthquakes in ∼1100, 1255, and 1344 AD, and emplacing roughly >5 km3 of debris that forms the Pokhara Formation. We offer a first systematic sedimentological study of this formation, revealing four lithofacies characterized by thick sequences of mid-fan fluvial conglomerates, debris-flow beds, and fan-marginal slackwater deposits. New geochemical provenance analyses reveal that these upstream dipping deposits of Higher Himalayan origin contain lenses of locally derived river clasts that mark time gaps between at least three major sediment pulses that buried different parts of the fan. The spatial pattern of 14C dates across the fan and the provenance data are key to distinguishing these individual sediment pulses, as these are not evident from their sedimentology alone. Our study demonstrates how geomorphic and sedimentary evidence of catastrophic valley infill can help to independently verify and augment paleoseismological fault-trench records of great Himalayan earthquakes, while offering unparalleled insights into their long-term geomorphic impacts on major drainage basins.

  18. An ongoing earthquake sequence near Dhaka, Bangladesh, from regional recordings

    Science.gov (United States)

    Howe, M.; Mondal, D. R.; Akhter, S. H.; Kim, W.; Seeber, L.; Steckler, M. S.

    2013-12-01

    of this population to earthquakes is amplified by poor infrastructure and building codes. The only event in this sequence included in the global Centroid Moment Tensor (CMT) catalog is a Mw 5.1 strike-slip event 18 km deep. At least 10 events in this sequence have been recorded globally (ISC). Many more events from the sequence have been recorded by a regional array of seismographs we have operated in Bangladesh since 2007. We apply several techniques to these data to explore source parameters and dimensions of seismogenesis in this sequence. We present both double-difference relocations and waveform modeling, which provide constraints on the source characteristics. Using the Mw 5.1 and other regional events as calibration, we obtain source parameters for several other events in the sequence. This sequence is ideal for double-difference relocation techniques because the source-receiver paths of the events in the sequence, recorded regionally, are very similar. The event relocation enables us to obtain accurate estimates of fault dimensions of this source. By combining accurate spatial dimensions of the source, the depth range of seismogenesis for the source zone, and well-constrained source parameters of events within the sequence, it we assess the maximum size of possible ruptures in this source.

  19. Unusual downhole and surface free-field records near the Carquinez Strait bridges during the 24 August 2014 Mw6.0 South Napa, California earthquake

    Science.gov (United States)

    Çelebi, Mehmet; Ghahari, S. Farid; Taciroglu, Ertugrul

    2015-01-01

    This paper reports the results of Part A of a study of the recorded strong-motion accelerations at the well-instrumented network of the two side-by-side parallel bridges over the Carquinez Strait during the 24 August 2014 (Mw6.0 ) South Napa, Calif. earthquake that occurred at 03:20:44 PDT with epicentral coordinates 38.22N, 122.31W. (http://earthquake.usgs.gov/earthquakes/eqarchives/poster/2014/20140824.php, last accessed on October 17, 2014). Both bridges and two boreholes were instrumented by the California Strong motion Instrumentation Program (CSMIP) of California Geological Survey (CGS) (Shakal et al., 2014). A comprehensive comparison of several ground motion prediction equations as they relate to recorded ground motions of the earthquake is provided by Baltay and Boatright (2015).

  20. The 5th July 1930 earthquake at Montilla (S Spain). Use of regionally recorded smoked paper seismograms

    Science.gov (United States)

    Batlló, J.; Stich, D.; Macià, R.; Morales, J.

    2009-04-01

    On the night of 5th July 1930 a damaging earthquake struck the town of Montilla (near Córdoba, S-Spain) and its surroundings. Magnitude estimation for this earthquake is M=5, and its epicentral intensity has been evaluated as VIII (MSK). Even it is an earthquake of moderate size, it is the largest one in-strumentally recorded in this region. This makes this event of interest for a better definition of the regional seismicity. For this reason we decided to study a new its source from the analysis of the available contemporary seismograms and related documents. A total of 25 seismograms from 11 seismic stations have been collected and digitized. Processing of some of the records has been difficult because they were obtained from microfilm or contemporary reproductions on journals. Most of them are on smoked paper and recorded at regional distances. This poses a good opportunity to test the limits of the use of such low frequency - low dynamics recorded seismograms for the study of regional events. Results are promising: Using such regional seismograms the event has been relocated, its magnitude recalculated (Mw 5.1) and inversion of waveforms to elucidate its focal mechanism has been performed. We present the results of this research and its consequences for the regional seismicity and we compare them with present smaller earthquakes occurred in the same place and with the results obtained for earthquakes of similar size occurred more to the East on 1951.

  1. Seismic demand evaluation based on actual earthquake records

    International Nuclear Information System (INIS)

    Jhaveri, D.P.; Czarnecki, R.M.; Kassawara, R.P.; Singh, A.

    1990-01-01

    Seismic input in the form of floor response spectra (FRS) are needed in seismic design and evaluation of equipment in nuclear power plants (NPPs). These are typically determined by analytical procedures using mathematical models of NPP structures and are known to be very conservative. Recorded earthquake data, in the form of acceleration response spectra computed from the recorded acceleration time histories, have been collected from NPP structures located in seismically active areas. Statistics of the ratios, or amplification factors, between the FRS at typical floors and the acceleration response spectra at the basemat or in the freefield, are obtained for typical NPP structures. These amplification factors are typically in terms of the peak spectral and zero period values, as well as a function of frequency. The average + 1σ values of these ratios, for those cases where enough data are available, are proposed to be used as limits to analytically calculated FRS, or for construction of simplified FRS for determining seismic input or demand in equipment qualification. (orig.)

  2. Data quality of seismic records from the Tohoku, Japan earthquake as recorded across the Albuquerque Seismological Laboratory networks

    Science.gov (United States)

    Ringler, A.T.; Gee, L.S.; Marshall, B.; Hutt, C.R.; Storm, T.

    2012-01-01

    Great earthquakes recorded across modern digital seismographic networks, such as the recent Tohoku, Japan, earthquake on 11 March 2011 (Mw = 9.0), provide unique datasets that ultimately lead to a better understanding of the Earth's structure (e.g., Pesicek et al. 2008) and earthquake sources (e.g., Ammon et al. 2011). For network operators, such events provide the opportunity to look at the performance across their entire network using a single event, as the ground motion records from the event will be well above every station's noise floor.

  3. Earthquake source properties from instrumented laboratory stick-slip

    Science.gov (United States)

    Kilgore, Brian D.; McGarr, Arthur F.; Beeler, Nicholas M.; Lockner, David A.; Thomas, Marion Y.; Mitchell, Thomas M.; Bhat, Harsha S.

    2017-01-01

    Stick-slip experiments were performed to determine the influence of the testing apparatus on source properties, develop methods to relate stick-slip to natural earthquakes and examine the hypothesis of McGarr [2012] that the product of stiffness, k, and slip duration, Δt, is scale-independent and the same order as for earthquakes. The experiments use the double-direct shear geometry, Sierra White granite at 2 MPa normal stress and a remote slip rate of 0.2 µm/sec. To determine apparatus effects, disc springs were added to the loading column to vary k. Duration, slip, slip rate, and stress drop decrease with increasing k, consistent with a spring-block slider model. However, neither for the data nor model is kΔt constant; this results from varying stiffness at fixed scale.In contrast, additional analysis of laboratory stick-slip studies from a range of standard testing apparatuses is consistent with McGarr's hypothesis. kΔt is scale-independent, similar to that of earthquakes, equivalent to the ratio of static stress drop to average slip velocity, and similar to the ratio of shear modulus to wavespeed of rock. These properties result from conducting experiments over a range of sample sizes, using rock samples with the same elastic properties as the Earth, and scale-independent design practices.

  4. Empirical relations between instrumental and seismic parameters of some strong earthquakes of Colombia

    International Nuclear Information System (INIS)

    Marin Arias, Juan Pablo; Salcedo Hurtado, Elkin de Jesus; Castillo Gonzalez, Hardany

    2008-01-01

    In order to establish the relationships between macroseismic and instrumental parameters, macroseismic field of 28 historical earthquakes that produced great effects in the Colombian territory were studied. The integration of the parameters was made by using the methodology of Kaussel and Ramirez (1992), for great Chilean earthquakes; Kanamori and Anderson (1975) and Coppersmith and Well (1994) for world-wide earthquakes. Once determined the macroseismic and instrumental parameters it was come to establish the model of the source of each earthquake, with which the data base of these parameters was completed. For each earthquake parameters related to the local and normal macroseismic epicenter were complemented, depth of the local and normal center, horizontal extension of both centers, vertical extension of the normal center, model of the source, area of rupture. The obtained empirical relations from linear equations, even show behaviors very similar to the found ones by other authors for other regions of the world and to world-wide level. The results of this work allow establishing that certain mutual non compatibility exists between the area of rupture and the length of rupture determined by the macroseismic methods, with parameters found with instrumental data like seismic moment, Ms magnitude and Mw magnitude.

  5. Earthquakes

    Science.gov (United States)

    An earthquake happens when two blocks of the earth suddenly slip past one another. Earthquakes strike suddenly, violently, and without warning at any time of the day or night. If an earthquake occurs in a populated area, it may cause ...

  6. Validation of Atmosphere/Ionosphere Signals Associated with Major Earthquakes by Multi-Instrument Space-Borne and Ground Observations

    Science.gov (United States)

    Ouzounov, Dimitar; Pulinets, Sergey; Hattori, Katsumi; Parrot, Michel; Liu, J. Y.; Yang, T. F.; Arellano-Baeza, Alonso; Kafatos, M.; Taylor, Patrick

    2012-01-01

    regions of the atmosphere and the modifications, by dc electric fields, in the ionosphere-atmosphere electric circuit. We retrospectively analyzed temporal and spatial variations of four different physical parameters (gas/radon counting rate, lineaments change, long-wave radiation transitions and ionospheric electron density/plasma variations) characterizing the state of the lithosphere/atmosphere coupling several days before the onset of the earthquakes. Validation processes consist in two phases: A. Case studies for seven recent major earthquakes: Japan (M9.0, 2011), China (M7.9, 2008), Italy (M6.3, 2009), Samoa (M7, 2009), Haiti (M7.0, 2010) and, Chile (M8.8, 2010) and B. A continuous retrospective analysis was preformed over two different regions with high seismicity- Taiwan and Japan for 2003-2009. Satellite, ground surface, and troposphere data were obtained from Terra/ASTER, Aqua/AIRS, POES and ionospheric variations from DEMETER and COSMIC-I data. Radon and GPS/TEC were obtaining from monitoring sites in Taiwan, Japan and Italy and from global ionosphere maps (GIM) respectively. Our analysis of ground and satellite data during the occurrence of 7 global earthquakes has shown the presence of anomalies in the atmosphere. Our results for Tohoku M9.0 earthquake show that on March 7th, 2011 (4 days before the main shock and 1 day before the M7.2 foreshock of March 8, 2011) a rapid increase of emitted infrared radiation was observed by the satellite data and an anomaly was developed near the epicenter. The GPS/TEC data indicate an increase and variation in electron density reaching a maximum value on March 8. From March 3 to 11 a large increase in electron concentration was recorded at all four Japanese ground-based ionosondes, which returned to normal after the main earthquake. Similar approach for analyzing atmospheric and ionospheric parameters has been applied for China (M7.9, 2008), Italy (M6.3, 2009), Samoa (M7, 2009), Haiti (M7.0, 2010) and Chile (M8.8, 2010

  7. An Impulse Electric Motor for Driving Recording Instruments

    Science.gov (United States)

    Joachim, W F

    1923-01-01

    The chief purpose in undertaking the development of this synchronous motor was the creation of a very small, compact power source, capable of driving the film drums of the recording aircraft instruments designed by the staff of the National Advisory Committee for Aeronautics.

  8. An algorithm of local earthquake detection from digital records

    Directory of Open Access Journals (Sweden)

    A. PROZOROV

    1978-06-01

    Full Text Available The problem of automatical detection of earthquake signals in seismograms
    and definition of first arrivals of p and s waves is considered.
    The algorithm is based on the analysis of t(A function which represents
    the time of first appearence of a number of going one after another
    swings of amplitudes greather than A in seismic signals. It allows to explore
    such common features of seismograms of earthquakes as sudden
    first p-arrivals of amplitude greater than general amplitude of noise and
    after the definite interval of time before s-arrival the amplitude of which
    overcomes the amplitude of p-arrival. The method was applied to
    3-channel recods of Friuli aftershocks, ¿'-arrivals were defined correctly
    in all cases; p-arrivals were defined in most cases using strict criteria of
    detection. Any false signals were not detected. All p-arrivals were defined
    using soft criteria of detection but less reliability and two false events
    were obtained.

  9. Ionospheric characteristics prior to the greatest earthquake in recorded history

    Science.gov (United States)

    Villalobos, C. U.; Bravo, M. A.; Ovalle, E. M.; Foppiano, A. J.

    2016-03-01

    Although several reports on the variations of some radio observed ionospheric properties prior to the very large Chile earthquakes of 21-22 May 1960 have been published, no one up to now has reported on the variations of simultaneous E- and F-region characteristics observed at Concepción (36.8°S; 73.0°W) using a ground based ionosonde. This paper analyses values of the NmE, NmEs, h'E, NmF2, h'F, M3000F2 and fmin. Possible solar and geomagnetic activity effects are first identified and then anomalies are calculated for all characteristics using reference values (15-day running medians ± interquartile range). Occasions when anomalies are larger than an upper threshold and less than a lower threshold are discussed and compared, whenever possible, with other published studies. Further study is suggested to unambiguously associate some found possible Es-layer and M3000F2 anomalies with very strong earthquakes.

  10. Broadband records of earthquakes in deep gold mines and a comparison with results from SAFOD, California

    Science.gov (United States)

    McGarr, Arthur F.; Boettcher, M.; Fletcher, Jon Peter B.; Sell, Russell; Johnston, Malcolm J.; Durrheim, R.; Spottiswoode, S.; Milev, A.

    2009-01-01

    For one week during September 2007, we deployed a temporary network of field recorders and accelerometers at four sites within two deep, seismically active mines. The ground-motion data, recorded at 200 samples/sec, are well suited to determining source and ground-motion parameters for the mining-induced earthquakes within and adjacent to our network. Four earthquakes with magnitudes close to 2 were recorded with high signal/noise at all four sites. Analysis of seismic moments and peak velocities, in conjunction with the results of laboratory stick-slip friction experiments, were used to estimate source processes that are key to understanding source physics and to assessing underground seismic hazard. The maximum displacements on the rupture surfaces can be estimated from the parameter , where  is the peak ground velocity at a given recording site, and R is the hypocentral distance. For each earthquake, the maximum slip and seismic moment can be combined with results from laboratory friction experiments to estimate the maximum slip rate within the rupture zone. Analysis of the four M 2 earthquakes recorded during our deployment and one of special interest recorded by the in-mine seismic network in 2004 revealed maximum slips ranging from 4 to 27 mm and maximum slip rates from 1.1 to 6.3 m/sec. Applying the same analyses to an M 2.1 earthquake within a cluster of repeating earthquakes near the San Andreas Fault Observatory at Depth site, California, yielded similar results for maximum slip and slip rate, 14 mm and 4.0 m/sec.

  11. Seismic fragility analyses of nuclear power plant structures based on the recorded earthquake data in Korea

    International Nuclear Information System (INIS)

    Joe, Yang Hee; Cho, Sung Gook

    2003-01-01

    This paper briefly introduces an improved method for evaluating seismic fragilities of components of nuclear power plants in Korea. Engineering characteristics of small magnitude earthquake spectra recorded in the Korean peninsula during the last several years are also discussed in this paper. For the purpose of evaluating the effects of the recorded earthquake on the seismic fragilities of Korean nuclear power plant structures, several cases of comparative studies have been performed. The study results show that seismic fragility analysis based on the Newmark's spectra in Korea might over-estimate the seismic capacities of Korean facilities. (author)

  12. Coherency analysis of accelerograms recorded by the UPSAR array during the 2004 Parkfield earthquake

    DEFF Research Database (Denmark)

    Konakli, Katerina; Kiureghian, Armen Der; Dreger, Douglas

    2014-01-01

    Spatial variability of near-fault strong motions recorded by the US Geological Survey Parkfield Seismograph Array (UPSAR) during the 2004 Parkfield (California) earthquake is investigated. Behavior of the lagged coherency for two horizontal and the vertical components is analyzed by separately...

  13. Continuous estimates on the earthquake early warning magnitude by use of the near-field acceleration records

    Science.gov (United States)

    Li, Jun; Jin, Xing; Wei, Yongxiang; Zhang, Hongcai

    2013-10-01

    In this article, the seismic records of Japan's Kik-net are selected to measure the acceleration, displacement, and effective peak acceleration of each seismic record within a certain time after P wave, then a continuous estimation is given on earthquake early warning magnitude through statistical analysis method, and Wenchuan earthquake record is utilized to check the method. The results show that the reliability of earthquake early warning magnitude continuously increases with the increase of the seismic information, the biggest residual happens if the acceleration is adopted to fit earthquake magnitude, which may be caused by rich high-frequency components and large dispersion of peak value in acceleration record, the influence caused by the high-frequency components can be effectively reduced if the effective peak acceleration and peak displacement is adopted, it is estimated that the dispersion of earthquake magnitude obviously reduces, but it is easy for peak displacement to be affected by long-period drifting. In various components, the residual enlargement phenomenon at vertical direction is almost unobvious, thus it is recommended in this article that the effective peak acceleration at vertical direction is preferred to estimate earthquake early warning magnitude. Through adopting Wenchuan strong earthquake record to check the method mentioned in this article, it is found that this method can be used to quickly, stably, and accurately estimate the early warning magnitude of this earthquake, which shows that this method is completely applicable for earthquake early warning.

  14. Preliminary analysis of strong-motion recordings from the 28 September 2004 Parkfield, California earthquake

    Science.gov (United States)

    Shakal, A.; Graizer, V.; Huang, M.; Borcherdt, R.; Haddadi, H.; Lin, K.-W.; Stephens, C.; Roffers, P.

    2005-01-01

    The Parkfield 2004 earthquake yielded the most extensive set of strong-motion data in the near-source region of a magnitude 6 earthquake yet obtained. The recordings of acceleration and volumetric strain provide an unprecedented document of the near-source seismic radiation for a moderate earthquake. The spatial density of the measurements alon g the fault zone and in the linear arrays perpendicular to the fault is expected to provide an exceptional opportunity to develop improved models of the rupture process. The closely spaced measurements should help infer the temporal and spatial distribution of the rupture process at much higher resolution than previously possible. Preliminary analyses of the peak a cceleration data presented herein shows that the motions vary significantly along the rupture zone, from 0.13 g to more than 2.5 g, with a map of the values showing that the larger values are concentrated in three areas. Particle motions at the near-fault stations are consistent with bilateral rupture. Fault-normal pulses similar to those observed in recent strike-slip earthquakes are apparent at several of the stations. The attenuation of peak ground acceleration with distance is more rapid than that indicated by some standard relationships but adequately fits others. Evidence for directivity in the peak acceleration data is not strong. Several stations very near, or over, the rupturing fault recorded relatively low accelerations. These recordings may provide a quantitative basis to understand observations of low near-fault shaking damage that has been reported in other large strike-slip earthquak.

  15. Seismic fragility analyses of nuclear power plant structures based on the recorded earthquake data in Korea

    International Nuclear Information System (INIS)

    Cho, Sung Gook; Joe, Yang Hee

    2005-01-01

    By nature, the seismic fragility analysis results will be considerably affected by the statistical data of design information and site-dependent ground motions. The engineering characteristics of small magnitude earthquake spectra recorded in the Korean peninsula during the last several years are analyzed in this paper. An improved method of seismic fragility analysis is evaluated by comparative analyses to verify its efficiency for practical application to nuclear power plant structures. The effects of the recorded earthquake on the seismic fragilities of Korean nuclear power plant structures are also evaluated from the comparative studies. Observing the obtained results, the proposed method is more efficient for the multi-modes structures. The case study results show that seismic fragility analysis based on the Newmark's spectra in Korea might over-estimate the seismic capacities of Korean facilities

  16. Seismic fragility analyses of nuclear power plant structures based on the recorded earthquake data in Korea

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Sung Gook [Department of Civil and Environmental System Engineering, University of Incheon, 177 Dohwa-dong, Nam-gu, Incheon 402-749 (Korea, Republic of)]. E-mail: sgcho@incheon.ac.kr; Joe, Yang Hee [Department of Civil and Environmental System Engineering, University of Incheon, 177 Dohwa-dong, Nam-gu, Incheon 402-749 (Korea, Republic of)

    2005-08-01

    By nature, the seismic fragility analysis results will be considerably affected by the statistical data of design information and site-dependent ground motions. The engineering characteristics of small magnitude earthquake spectra recorded in the Korean peninsula during the last several years are analyzed in this paper. An improved method of seismic fragility analysis is evaluated by comparative analyses to verify its efficiency for practical application to nuclear power plant structures. The effects of the recorded earthquake on the seismic fragilities of Korean nuclear power plant structures are also evaluated from the comparative studies. Observing the obtained results, the proposed method is more efficient for the multi-modes structures. The case study results show that seismic fragility analysis based on the Newmark's spectra in Korea might over-estimate the seismic capacities of Korean facilities.

  17. Thermal alteration of pyrite to pyrrhotite during earthquakes : New evidence of seismic slip in the rock record

    NARCIS (Netherlands)

    Yang, Tao; Dekkers, Mark J.; Chen, Jianye

    Seismic slip zones convey important information on earthquake energy dissipation and rupture processes. However, geological records of earthquakes along exhumed faults remain scarce. They can be traced with a variety of methods that establish the frictional heating of seismic slip, although each has

  18. Wrightwood and the earthquake cycle: What a long recurrence record tells us about how faults work

    Science.gov (United States)

    Weldon, R.; Scharer, K.; Fumal, T.; Biasi, G.

    2004-01-01

    The concept of the earthquake cycle is so well established that one often hears statements in the popular media like, "the Big One is overdue" and "the longer it waits, the bigger it will be." Surprisingly, data to critically test the variability in recurrence intervals, rupture displacements, and relationships between the two are almost nonexistent. To generate a long series of earthquake intervals and offsets, we have conducted paleoseismic investigations across the San Andreas fault near the town of Wrightwood, California, excavating 45 trenches over 18 years, and can now provide some answers to basic questions about recurrence behavior of large earthquakes. To date, we have characterized at least 30 prehistoric earthquakes in a 6000-yr-long record, complete for the past 1500 yr and for the interval 3000-1500 B.C. For the past 1500 yr, the mean recurrence interval is 105 yr (31-165 yr for individual intervals) and the mean slip is 3.2 m (0.7-7 m per event). The series is slightly more ordered than random and has a notable cluster of events, during which strain was released at 3 times the long-term average rate. Slip associated with an earthquake is not well predicted by the interval preceding it, and only the largest two earthquakes appear to affect the time interval to the next earthquake. Generally, short intervals tend to coincide with large displacements and long intervals with small displacements. The most significant correlation we find is that earthquakes are more frequent following periods of net strain accumulation spanning multiple seismic cycles. The extent of paleoearthquake ruptures may be inferred by correlating event ages between different sites along the San Andreas fault. Wrightwood and other nearby sites experience rupture that could be attributed to overlap of relatively independent segments that each behave in a more regular manner. However, the data are equally consistent with a model in which the irregular behavior seen at Wrightwood

  19. Experience with seismic instrumentation and real earthquake data at nuclear power plant Beznau Switzerland

    International Nuclear Information System (INIS)

    Sahgal, S.; Tinic, S.

    2005-01-01

    This paper deals with the aspects of design specification, bid evaluation and, seismic criteria used for the generation of seismic alarms etc. The paper also describes how the recorded data is utilized to check the various assumptions made in conjunction with the seismic plant design and seismic load generation. Out of some 8 seismic events registered so far only one event had the maximum recorded acceleration of approximately 28% of OBE Peak Ground Acceleration (PGA). From the real earthquakes experienced and the in-situ free-field ground accelerations recorded, the free-field response spectra were calculated. The calculated spectra are compared to the Regulatory Guide 1.60 Design Response Spectra scaled linearly to the site peak ground acceleration. The free field data recording units on the weathered rock and at the top of the soil provided a real data to calculate the site amplification factors. The in-situ amplification calculated is then compared to that used in the seismic design. The recorded acceleration time history at various plant grades were used to generate response spectra. The calculated response spectra were in turn compared to the spectra used in the seismic design. (authors)

  20. Strong motion recordings of the 2008/12/23 earthquake in Northern Italy: another case of very weak motion?

    Science.gov (United States)

    Sabetta, F.; Zambonelli, E.

    2009-04-01

    On December 23 2008 an earthquake of magnitude ML=5.1 (INGV) Mw=5.4 (INGV-Harvard Global CMT) occurred in northern Italy close to the cities of Parma and Reggio Emilia. The earthquake, with a macroseismic intensity of VI MCS, caused a very slight damage (some tens of unusable buildings and some hundreds of damaged buildings), substantially lower than the damage estimated by the loss simulation scenario currently used by the Italian Civil Protection. Due to the recent upgrading of the Italian strong motion network (RAN), the event has been recorded by a great number of accelerometers (the largest ever obtained in Italy for a single shock): 21 digital and 8 analog instruments with epicentral distances ranging from 16 to 140 km. The comparison of recorded PGA, PGV, Arias intensity, and spectral values with several widely used Ground Motion Prediction Equations (GMPEs) showed much lower ground motion values respect to the empirical predictions (a factor ranging from 4 to 2). A first explanation of the strong differences, in damage and ground motion, between actual data and predictions could be, at a first sight, attributed to the rather high focal depth of 27 km. However, even the adoption of GMPEs accounting for depth of the source and using hypocentral distance (Berge et al 2003, Pousse et al 2005), does not predict large differences in motions, especially at distances larger than 30 km where most of the data are concentrated and where the effect of depth on source-to-site distance is small. At the same time the adoption of the most recent GMPEs (Ambraseys et al 2005, Akkar & bommer 2007) taking into account the different magnitude scaling and the faster attenuation of small magnitudes through magnitude-dependent attenuation, does not show a better agreement with the recorded data. The real reasons of the above mentioned discrepancies need to be further investigated, however a possible explanation could be a low source rupture velocity, likewise the 2002 Molise

  1. Attenuation Characteristics of Strong Motions during the 2016 Kumamoto Earthquakes including Near-Field Records

    Science.gov (United States)

    Si, H.; Koketsu, K.; Miyake, H.; Ibrahim, R.

    2016-12-01

    During the two major earthquakes occurred in Kumamoto prefecture, at 21:26 on 14 April, 2016 (Mw 6.2, GCMT), and at 1:25 on 16 April, 2016 (Mw7.0, GCMT), a large number of strong ground motions were recorded, including those very close to the surface fault. In this study, we will discuss the attenuation characteristics of strong ground motions observed during the earthquakes. The data used in this study are mainly observed by K-NET, KiK-net, Osaka University, JMA and Kumamoto prefecture. The 5% damped acceleration response spectra (GMRotI50) are calculated based on the method proposed by Boore et al. (2006). PGA and PGV is defined as the larger one among the PGAs and PGVs of two horizontal components. The PGA, PGV, and GMRotI50 data were corrected to the bedrock with Vs of 1.5km/s based on the method proposed by Si et al. (2016) using the average shear wave velocity (Vs30) and the thickness of sediments over the bedrock. The thickness is estimated based on the velocity structure model provided by J-SHIS. We use a source model proposed by Koketsu et al. (2016) to calculate the fault distance and the median distance (MED) which defined as the closest distance from a station to the median line of the fault plane (Si et al., 2014). We compared the observed PGAs, PGVs, and GMRotI50 with the GMPEs developed in Japan using MED (Si et al., 2014). The predictions by the GMPEs are generally consistent with the observations during the two Kumamoto earthquakes. The results of the comparison also indicated that, (1) strong motion records from the earthquake on April 14th are generally consistent with the predictions by GMPE, however, at the periods of 0.5 to 2 seconds, several records close to the fault plane show larger amplitudes than the predictions by GMPE, including the KiK-net station Mashiki (KMMH16); (2) for the earthquake on April 16, the PGAs and GMRotI50 at periods from 0.1s to 0.4s with short distance from the fault plane are slightly smaller than the predictions by

  2. Recorded earthquake responses from the integrated seismic monitoring network of the Atwood Building, Anchorage, Alaska

    Science.gov (United States)

    Celebi, M.

    2006-01-01

    An integrated seismic monitoring system with a total of 53 channels of accelerometers is now operating in and at the nearby free-field site of the 20-story steel-framed Atwood Building in highly seismic Anchorage, Alaska. The building has a single-story basement and a reinforced concrete foundation without piles. The monitoring system comprises a 32-channel structural array and a 21-channel site array. Accelerometers are deployed on 10 levels of the building to assess translational, torsional, and rocking motions, interstory drift (displacement) between selected pairs of adjacent floors, and average drift between floors. The site array, located approximately a city block from the building, comprises seven triaxial accelerometers, one at the surface and six in boreholes ranging in depths from 15 to 200 feet (???5-60 meters). The arrays have already recorded low-amplitude shaking responses of the building and the site caused by numerous earthquakes at distances ranging from tens to a couple of hundred kilometers. Data from an earthquake that occurred 186 km away traces the propagation of waves from the deepest borehole to the roof of the building in approximately 0.5 seconds. Fundamental structural frequencies [0.58 Hz (NS) and 0.47 Hz (EW)], low damping percentages (2-4%), mode coupling, and beating effects are identified. The fundamental site frequency at approximately 1.5 Hz is close to the second modal frequencies (1.83 Hz NS and 1.43 EW) of the building, which may cause resonance of the building. Additional earthquakes prove repeatability of these characteristics; however, stronger shaking may alter these conclusions. ?? 2006, Earthquake Engineering Research Institute.

  3. Variations of local seismic response in Benevento (Southern Italy) using earthquakes and ambient noise recordings

    Science.gov (United States)

    Improta, Luigi; di Giulio, Giuseppe; Rovelli, Antonio

    The city of Benevento (Southern Italy) has been repeatedly struck by large historical earthquakes. A heterogeneous geologic structure and widespread soft soil conditions make the estimation of site effects crucial for the seismic hazard assessment of the city. From 2000 until 2004, we installed seismic stations to collect earthquake data over zones with different geological conditions. Despite the high level of urban noise, we recorded more than 150 earthquakes at twelve sites. This data set yields the first, well documented experimental evidence for weak to moderate local amplifications. We investigated site effects primarily by the classical spectral ratio technique (CSR) using a rock station placed on the Benevento hill as reference. All sites in the Calore river valley and in the eastern part of the Benevento hill show a moderate high-frequency (f > 4 Hz) amplification peak. Conversely, sites in the Sabato river valley share weak-to-moderate amplification in a wide frequency band (from 1-2 to 7-10 Hz), without evident frequency peaks. Application of no-reference-site techniques to earthquake and noise data confirms the results of the CSRs in the sites of the Calore river valley and of the eastern part of the Benevento hill, but fails in providing indications for site effects in the Sabato river valley, being the H/V ratios nearly flat. One-dimensional modeling indicates that the ground motion amplification can be essentially explained in terms of a vertically varying geologic structure. High-frequency narrow peaks are caused by the strong impedance contrast existing between near-surface soft deposits and stiff cemented conglomerates. Conversely, broad-band amplifications in the Sabato river valley are likely due to a more complex layering with weak impedance contrasts both in the shallow and deep structure of the valley.

  4. Tilt Precursors before Earthquakes on the San Andreas Fault, California.

    Science.gov (United States)

    Johnston, M J; Mortensen, C E

    1974-12-13

    An array of 14 biaxial shallow-borehole tiltmeters (at 1O(-7) radian sensitivity) has been installed along 85 kilometers of the San Andreas fault during the past year. Earthquake-related changes in tilt have been simultaneously observed on up to four independent instruments. At earthquake distances greater than 10 earthquake source dimensions, there are few clear indications of tilt change. For the four instruments with the longest records (> 10 months), 26 earthquakes have occurred since July 1973 with at least one instrument closer than 10 source dimensions and 8 earthquakes with more than one instrument within that distance. Precursors in tilt direction have been observed before more than 10 earthquakes or groups of earthquakes, and no similar effect has yet been seen without the occurrence of an earthquake.

  5. Preliminary earthquake locations in the Kenai Peninsula recorded by the MOOS Array and their relationship to structure in the 1964 great earthquake zone

    Science.gov (United States)

    Li, J.; Abers, G. A.; Christensen, D. H.; Kim, Y.; Calkins, J. A.

    2011-12-01

    Earthquakes in subduction zones are mostly generated at the interface between the subducting and overlying plates. In 2006-2009, the MOOS (Multidisciplinary Observations Of Subduction) seismic array was deployed around the Kenai Peninsula, Alaska, consisting of 34 broadband seismometers recording for 1-3 years. This region spans the eastern end of the Aleutian megathrust that ruptured in the 1964 Mw 9.2 great earthquake, the second largest recorded earthquake, and ongoing seismicity is abundant. Here, we report an initial analysis of seismicity recorded by MOOS, in the context of preliminary imaging. There were 16,462 events detected in one year from initial STA/LTA signal detections and subsequent event associations from the MOOS Array. We manually reviewed them to eliminate distant earthquakes and noise, leaving 11,879 local earthquakes. To refine this catalog, an adaptive auto-regressive onset estimation algorithm was applied, doubling the original dataset and producing 20,659 P picks and 22,999 S picks for one month (September 2007). Inspection shows that this approach lead to almost negligible false alarms and many more events than hand picking. Within the well-sampled part of the array, roughly 200 km by 300 km, we locate 250% more earthquakes for one month than the permanent network catalog, or 10 earthquakes per day on this patch of the megathrust. Although the preliminary locations of earthquakes still show some scatter, we can see a concentration of events in a ~20-km-wide belt, part of which can be interpreted as seismogenic thrust zone. In conjunction with the seismicity study, we are imaging the plate interface with receiver functions. The main seismicity zone corresponds to the top of a low-velocity layer imaged in receiver functions, nominally attributed to the top of the downgoing plate. As we refine velocity models and apply relative relocation algorithms, we expect to improve the precision of the locations substantially. When combined with image

  6. The severity of an earthquake

    Science.gov (United States)

    ,

    1997-01-01

    The severity of an earthquake can be expressed in terms of both intensity and magnitude. However, the two terms are quite different, and they are often confused. Intensity is based on the observed effects of ground shaking on people, buildings, and natural features. It varies from place to place within the disturbed region depending on the location of the observer with respect to the earthquake epicenter. Magnitude is related to the amount of seismic energy released at the hypocenter of the earthquake. It is based on the amplitude of the earthquake waves recorded on instruments

  7. 2001 Bhuj, India, earthquake engineering seismoscope recordings and Eastern North America ground-motion attenuation relations

    Science.gov (United States)

    Cramer, C.H.; Kumar, A.

    2003-01-01

    Engineering seismoscope data collected at distances less than 300 km for the M 7.7 Bhuj, India, mainshock are compatible with ground-motion attenuation in eastern North America (ENA). The mainshock ground-motion data have been corrected to a common geological site condition using the factors of Joyner and Boore (2000) and a classification scheme of Quaternary or Tertiary sediments or rock. We then compare these data to ENA ground-motion attenuation relations. Despite uncertainties in recording method, geological site corrections, common tectonic setting, and the amount of regional seismic attenuation, the corrected Bhuj dataset agrees with the collective predictions by ENA ground-motion attenuation relations within a factor of 2. This level of agreement is within the dataset uncertainties and the normal variance for recorded earthquake ground motions.

  8. Roman, Visigothic and Islamic evidence of earthquakes recorded in the archaeological site of “El Tolmo de Minateda” (Prebetic Zone, southeast of Spain)

    Science.gov (United States)

    Rodríguez-Pascua, M.A.; Abad Casal, L.; Pérez-López, R.; Gamo Parra, B.; Silva, P.G.; Garduño-Monroy, V.H.; Giner-Robles, J.L.; Perucha, M.A.; Israde-Alcántara, I.; Bischoff, J.; Calvo, J.P.

    2013-01-01

    The archaeological site of “El Tolmo de Minateda” is located within the Albacete province (SE of Spain) and shows a continuous time record of ancient civilizations from 3500 yr BP onwards. However, three temporal gaps were identified in this archaeological record, all of them in relationship with a sudden and unclear abandonment of the city (Centuries 1st, 7th and 9-10th). The Archaeological Earthquake Effects (EAEs) supports the possibility that moderate to strong earthquakes were the cause of such abandonments: oriented columns fallen, collapsed walls and arches, abandonment of irrigation systems and fresh-water supplies, crashed pottery, etc. Despite of the scarce of instrumental seismicity and a few historical chronicles, paleoseismic studies performed in the neighbouring zone (Tobarra) suggest the presence of closer seismic sources as faults (Pozohondo Fault) affecting Quaternary alluvial, lacustrine deposits and colluviums. In this work, we propose the possibility that three moderate earthquakes devastated the ancient Roman city of Ilunum (Century 1st AD), the Visigothic city of Elo (Century 7th AD) and the Islamic city of Madinat Iyih (Century 9th-10thAD), all of them the same place: “El Tolmo de Minateda”.

  9. Tsunami source of the 2016 Muisne, Ecuador Earthquake inferred from tide gauge and DART records

    Science.gov (United States)

    Adriano, B.; Fujii, Y.; Koshimura, S.

    2016-12-01

    On April 16, 2016 an earthquake occurred in the central coast of Ecuador (0.382°N 79.922°W, Mw=7.8 at 23:58:36.980 UTC according to U.S. Geological Service). It was reported that widespread damage occurred at several towns of Monabi coastal province. According to reports from the Ecuador Government, more than 15,000 buildings were damaged. This earthquake generated a relatively small tsunami that was detected at several tide gauge station as well as offshore DARTs (Deep Ocean Tsunami Detection Buoys). This study aims to investigate the tsunami source of the 2016 Muisne Earthquake using inversion of recorded tsunami waveform signals. The INOCAR (Instituto Oceanográfico de la Armada in Spanish) of the Ecuador provided the tide records of Esmeraldas, Manta, and La Libertad ports. In addition, the DIMAR (Dirección General Marítima in Spanish) of Colombia provided the tide record of Tumaco port. Finally, waveform signal from two DARTs were also employed. These waveform records usually include ocean tides, which we removed by applying a high-pass filter. To estimate the extent of the tsunami source and the slip distribution, we divide the tsunami source into 4 subfaults that covers the aftershock area during one month after the mainshock. The subfault size is 30 km x 60 km with a top depth of 10 km. The focal mechanisms for all the subfaults were taken form the USGS solution of the mainshock. The inversion result showed that the largest slip was located around the epicenter with a maximum value of 3.1 m. The estimated moment magnitude was calculated as Mw=7.78 (5.89E+20 N-m), which is slightly smaller than the proposed by USGS (Mw7.8, moment 7.05E+20 N-m). The estimated slip distribution suggested that the fault rupture started near the epicenter and propagated from north to south. This evidence is supported by the aftershock distribution, which is higher to the south of the epicenter with a main aftershock of Mw=6.0 on April 22.

  10. An Arduino project to record ground motion and to learn on earthquake hazard at high school

    Science.gov (United States)

    Saraò, Angela; Barnaba, Carla; Clocchiatti, Marco; Zuliani, David

    2015-04-01

    Through a multidisciplinary work that integrates Technology education with Earth Sciences, we implemented an educational program to raise the students' awareness of seismic hazard and to disseminate good practices of earthquake safety. Using free software and low-cost open hardware, the students of a senior class of the high school Liceo Paschini in Tolmezzo (NE Italy) implemented a seismograph using the Arduino open-source electronics platform and the ADXL345 sensors to emulate a low cost seismometer (e.g. O-NAVI sensor of the Quake-Catcher Network, http://qcn.stanford.edu). To accomplish their task the students were addressed to use the web resources for technical support and troubleshooting. Shell scripts, running on local computers under Linux OS, controlled the process of recording and display data. The main part of the experiment was documented using the DokuWiki style. Some propaedeutic lessons in computer sciences and electronics were needed to build up the necessary skills of the students and to fill in the gap of their background knowledge. In addition lectures by seismologists and laboratory activity allowed the class to exploit different aspects of the physics of the earthquake and particularly of the seismic waves, and to become familiar with the topics of seismic hazard through an inquiry-based learning. The Arduino seismograph achieved can be used for educational purposes and it can display tremors on the local network of the school. For sure it can record the ground motion due to a seismic event that can occur in the area, but further improvements are necessary for a quantitative analysis of the recorded signals.

  11. Characteristics of seismic sources of some Asian earthquakes and Soviet underground explosions from Gauribidanur array records

    International Nuclear Information System (INIS)

    Basu, T.K.; Arora, S.K.

    1987-01-01

    Among one hundred sixty-five shallow-focus earthquakes which occurred over a six-year period (1980-1985) in thirty-five different Asian provinces, Gauribidanur array (GBA) P-wave seismograms of all of them and P c P seismograms of thirty-one of them from fourteen regions were processed to deduce temporal and spectral characteristics of their sources. These were compared with the corresponding features deduced earlier (Basu and Arora ; 1985, 1986) from eighty-eight known and presumed Soviet underground explosions. The identifiers that yielded wider separation between earthquakes and explosions included among others: (i) cube root of signal complexity per unit TMF (third moment of frequency: CTMF parameter), (ii) spectral energy ratio of P c P in two distinct frequency passbands (SENR Parameters), and (iii) normalized time-window energy ratio (NTENR parameter) and normalized spectral energy ratio (NSENR parameter) of P and P c P signals. The last two of these particularly helped to accentuate the main phase and the relative high-frequency content in the P c P record, which considerably increased the efficacy of the P c P discriminant. 5 refs., 10 figures, 6 tables. (author)

  12. Assessment of soil-structure interaction on a 51-story building from the spectral ratio of earthquake recordings

    Directory of Open Access Journals (Sweden)

    Liu Kun-Sung

    2017-01-01

    Full Text Available The soil-structure interaction (SSI can significantly alter the characteristics of recorded motions in buildings. The ratio of Fourier amplitude spectrum of the top-story accelerations to that of the foundation accelerations permits the identification of the natural frequency of the fixed-base building. In this study, records of the Chi-Chi earthquake and the 1226 Hengchun earthquake doublet from the structural array in a 51-story highrise building are used to obtain the dynamic characteristics of the buildings by the transfer function (TF method. As a result, the acceleration amplification of seismic excitation on the 47th storey of buildings is 4.24, in the horizontal component, from the Chi-Chi earthquake data greater than those of the 1226 Hengchun earthquake doublet with a value of 2.82 and 2.06, respectively. In addition, from the spectral ratio of the accelerations (47th floor/basement, together with the Fourier Amplitude Spectrum (FAS of the 47th floor and basement accelerations, it is noted that the peaks of the 47th floor FAS and the spectral ratio appear to coincide with each other from the records of 1226 Hengchun earthquake doublet, suggesting that there is no significant SSI effects in both the longitudinal and transverse directions.

  13. MUG-OBS - Multiparameter Geophysical Ocean Bottom System : a new instrumental approach to monitor earthquakes.

    Science.gov (United States)

    hello, yann; Charvis, Philippe; Yegikyan, Manuk; verfaillie, Romain; Rivet, Diane

    2016-04-01

    Real time monitoring of seismic activity is a major issue for early warning of earthquakes and tsunamis. It can be done using regional scale wired nodes, such as Neptune in Canada and in the U.S, or DONET in Japan. Another approach to monitor seismic activity at sea is to deploying repeatedly OBS array like during the amphibious Cascadia Initiative (four time 1-year deployments), the Japanese Pacific Array (broadband OBSs "ocean-bottom broadband dispersion survey" with 2-years autonomy), the Obsismer program in the French Lesser Antilles (eight time 6-months deployments) and the Osisec program in Ecuador (four time 6-months deployments). These autonomous OBSs are self-recovered or recovered using an ROV. These systems are costly including ship time, and require to recover the OBS before to start working on data. Among the most recent alternative we developed a 3/4 years autonomy ocean bottom system with 9 channels (?) allowing the acquisition of different seismic or environmental parameters. MUG-OBS is a free falling instrument rated down to 6000 m. The installation of the sensor is monitored by acoustic commands from the surface and a health bulletin with data checking is recovered by acoustic during the installation. The major innovation is that it is possible to recover the data any time on demand (regularly every 6-months or after a crisis) using one of the 6 data-shuttles released from the surface by acoustic command using a one day fast cruise boat of opportunity. Since sensors stayed at the same location for 3 years, it is a perfect tool to monitor large seismic events, background seismic activity and aftershock distribution. Clock, drift measurement and GPS localization is automatic when the shuttle reaches the surface. For remote areas, shuttles released automatically and a seismic events bulletin is transmitted. Selected data can be recovered by two-way Iridium satellite communication. After a period of 3 years the main station is self-recovered by

  14. Earthquake Recurrence and the Resolution Potential of Tectono‐Geomorphic Records

    KAUST Repository

    Zielke, Olaf

    2018-01-01

    combination consistently reproduces the above‐mentioned field observations. Doing so, I find that neither a purely characteristic earthquake (CE) nor a Gutenberg–Richter (GR) earthquake recurrence model is able to consistently reproduce those field

  15. Magnetic characterisation of recording materials: design, instrumentation and experimental methods

    NARCIS (Netherlands)

    Samwel, E.O.

    1995-01-01

    The progress being made in the field of magnetic recording is extremely fast. The need to keep this progress going, leads to new types of recording materials which require advanced measurement systems and measurement procedures. Furthermore, the existing measurement methods need to be reviewed as

  16. Near Fault Strong Ground Motion Records in the Kathmandu Valley during the 2015 Gorkha Nepal Earthquake

    Science.gov (United States)

    Takai, N.; Shigefuji, M.; Rajaure, S.; Bijukchhen, S.; Ichiyanagi, M.; Dhital, M. R.; Sasatani, T.

    2015-12-01

    Kathmandu is the capital of Nepal and is located in the Kathmandu Valley, which is formed by soft lake sediments of Plio-Pleistocene origin. Large earthquakes in the past have caused significant damage as the seismic waves were amplified in the soft sediments. To understand the site effect of the valley structure, we installed continuous recording accelerometers in four different parts of the valley. Four stations were installed along a west-to-east profile of the valley at KTP (Kirtipur; hill top), TVU (Kirtipur; hill side), PTN (Patan) and THM (Thimi). On 25 April 2015, a large interplate earthquake Mw 7.8 occurred in the Himalayan Range of Nepal. The focal area estimated was about 200 km long and 150 km wide, with a large slip area under the Kathmandu Valley where our strong motion observation stations were installed. The strong ground motions were observed during this large damaging earthquake. The maximum horizontal peak ground acceleration at the rock site was 271 cm s-2, and the maximum horizontal peak ground velocity at the sediment sites reached 112 cm s-1. We compared these values with the empirical attenuation formula for strong ground motions. We found the peak accelerations were smaller and the peak velocities were approximately the same as the predicted values. The rock site KTP motions are less affected by site amplification and were analysed further. The horizontal components were rotated to the fault normal (N205E) and fault parallel (N115E) directions using the USGS fault model. The velocity waveforms at KTP showed about 5 s triangular pulses on the N205E and the up-down components; however the N115E component was not a triangular pulse but one cycle sinusoidal wave. The velocity waveforms at KTP were integrated to derive the displacement waveforms. The derived displacements at KTP are characterized by a monotonic step on the N205E normal and up-down components. The displacement waveforms of KTP show permanent displacements of 130 cm in the fault

  17. Swedish National Seismic Network (SNSN). A short report on recorded earthquakes during the fourth quarter of the year 2010

    Energy Technology Data Exchange (ETDEWEB)

    Boedvarsson, Reynir (Uppsala Univ. (Sweden), Dept. of Earth Sciences)

    2011-01-15

    According to an agreement with Swedish Nuclear Fuel and Waste Management Company (SKB) and Uppsala Univ., the Dept. of Earth Sciences has continued to carry out observations of seismic events at seismic stations within the Swedish National Seismic Network (SNSN). This short report gives brief information about the recorded seismicity during October through December 2010. The Swedish National Seismic Network consists of 62 stations. During October through December, 2,241 events were located whereof 158 are estimated as real earthquakes, 1,457 are estimated as explosions, 444 are induced earthquakes in the vicinity of the mines in Kiruna and Malmberget and 182 events are still considered as uncertain but these are most likely explosions and are mainly located outside the network. One earthquake had a magnitude above M{sub L} = 2.0 during the period. In November one earthquake was located 13 km SW of Haernoesand with a magnitude of M{sub L} = 2.1. The largest earthquake in October had a magnitude of M{sub L} = 1.7 and was located 12 km NE of Eksjoe and in December an earthquake with a magnitude of M{sub L} = 1.8 was located 19 km north of Motala

  18. Full wave field recording of the vertical strain at SAFOD from local, regional and teleseismic earthquakes

    Science.gov (United States)

    Ellsworth, W. L.; Karrenbach, M. H.; Zumberge, M. A.

    2017-12-01

    The main borehole at the San Andreas Fault Observatory at Depth (SAFOD) contains optical fibers cemented in place in between casing strings from the surface to just below the top of the basement. The fibers are under tension of approximately 1 N and are housed in a 0.9 mm diameter stainless steel tube. Earth strain is transmitted to the fiber by frictional contact with the tube wall. One fiber has been in use as a vertical strainmeter since 2005, measuring the total strain between 9 and 740 m by laser interferometry. In June 2017 we attached an OptaSense Distributed Acoustic Sensing (DAS) system, model ODH3.1, to a second fiber that terminates at 864 m depth. The DAS laser interrogator measures the strain over a gauge length with a set spacing between gauge intervals. For this experiment we set the gauge length to 10 m with 1 m spacing between gauges. Including the surface run of the fiber, this gives us 936 channels measuring the vertical strain at a sample interval of 0.4 msec (2500 samples/s). Continuous recording of the string produces approximately 1 TB/day. During one month of data collection, we recorded local, regional and teleseismic earthquakes. With this recording geometry, the DAS system captures the full vertical wavefield between the basement interface and free surface, revealing direct, converted and refracted waves. Both P- and S- strain waves are clearly visible in the data, even for 10 km deep earthquakes located almost directly below the well (see figure). The incident and surface reflected wavefields can be separated by frequency-wavenumber filtering due to the large-aperture and fine spatial and temporal sampling. Up- and downgoing strain waves illuminate the subsurface within the sensor array's depth range. Accurate arrival time determinations of the initial arrival phase are possible due to consistent wave forms recorded at 1 m spatial intervals that can be used for fine-scale shallow velocity model estimation.

  19. Investigations of anomalous gravity signals prior to 71 large earthquakes based on a 4-years long superconducting gravimeter records

    Directory of Open Access Journals (Sweden)

    Dijin Wang

    2017-09-01

    Full Text Available Using continuous 1-Hz sampling time-series recorded by a SG (superconducting gravimeter at Hsinchu station, Taiwan of China, we investigate the anomalous gravity signals prior to 71 large earthquakes with moment magnitude larger than 7.0 (Mw7.0 occurred between 1 Jan 2008 and 31 Dec 2011. We firstly evaluate the noise level of the SG records at Hsinchu (HS station in microseismic bands from 0.05 Hz to 0.1 Hz by computing the PSD (power spectral density of seismically quiet days selected based on the RMS of records. Based on the analysis of the noise level and the spectral features of the seismically quiet SG records at HS station, we detect AGSs (anomalous gravity signals prior to large earthquakes. We apply HHT (Hilbert-Huang transformation to establish the TFEP (time-frequency-energy paradigms and MS (marginal spectra of the SG data before the large earthquakes, and the characteristics of TFEP and MS of the SGs data during the typhoon event are also analyzed. By comparing the spectral characteristics of the SGs data during seismically quiet period, three types of AGSs are found; and the occurrence rate of AGSs before 71 earthquakes is given in terms of the cases with different epicenter distance and different focal depth. The statistical results show that 56.3% of all the examined large earthquakes were preceded by AGSs; and if we constrain the epicenter distance to be smaller than 3500 km and focal depth less than 300 km, 75.3% of the examined large earthquakes can be associated with the AGSs. Especially, we note that for all the large earthquakes occurred in the Eurasian plate in recent four years, the precursory AGSs can always be found in the SG data recorded at HS station. Our investigations suggest that the AGSs prior to large earthquakes may be related to focal depth, epicentre distance and location.

  20. Earthquake hazard evaluation for Switzerland

    International Nuclear Information System (INIS)

    Ruettener, E.

    1995-01-01

    Earthquake hazard analysis is of considerable importance for Switzerland, a country with moderate seismic activity but high economic values at risk. The evaluation of earthquake hazard, i.e. the determination of return periods versus ground motion parameters, requires a description of earthquake occurrences in space and time. In this study the seismic hazard for major cities in Switzerland is determined. The seismic hazard analysis is based on historic earthquake records as well as instrumental data. The historic earthquake data show considerable uncertainties concerning epicenter location and epicentral intensity. A specific concept is required, therefore, which permits the description of the uncertainties of each individual earthquake. This is achieved by probability distributions for earthquake size and location. Historical considerations, which indicate changes in public earthquake awareness at various times (mainly due to large historical earthquakes), as well as statistical tests have been used to identify time periods of complete earthquake reporting as a function of intensity. As a result, the catalog is judged to be complete since 1878 for all earthquakes with epicentral intensities greater than IV, since 1750 for intensities greater than VI, since 1600 for intensities greater than VIII, and since 1300 for intensities greater than IX. Instrumental data provide accurate information about the depth distribution of earthquakes in Switzerland. In the Alps, focal depths are restricted to the uppermost 15 km of the crust, whereas below the northern Alpine foreland earthquakes are distributed throughout the entire crust (30 km). This depth distribution is considered in the final hazard analysis by probability distributions. (author) figs., tabs., refs

  1. Microseismic data records fault activation before and after a Mw 4.1 induced earthquake

    Science.gov (United States)

    Eyre, T.; Eaton, D. W. S.

    2017-12-01

    Several large earthquakes (Mw 4) have been observed in the vicinity of the town of Fox Creek, Alberta. These events have been determined to be induced earthquakes related to hydraulic fracturing in the region. The largest of these has a magnitude Mw = 4.1, and is associated with a hydraulic-fracturing treatment close to Crooked Lake, about 30 km west of Fox Creek. The underlying factors that lead to localization of the high numbers of hydraulic fracturing induced events in this area remain poorly understood. The treatment that is associated with the Mw 4.1 event was monitored by 93 shallow three-level borehole arrays of sensors. Here we analyze the temporal and spatial evolution of the microseismic and seismic data recorded during the treatment. Contrary to expected microseismic event clustering parallel to the principal horizontal stress (NE - SW), the events cluster along obvious fault planes that align both NNE - SSW and N - S. As the treatment well is oriented N - S, it appears that each stage of the treatment intersects a new portion of the fracture network, causing seismicity to occur. Focal-plane solutions support a strike-slip failure along these faults, with nodal planes aligning with the microseismic cluster orientations. Each fault segment is activated with a cluster of microseismicity in the centre, gradually extending along the fault as time progresses. Once a portion of a fault is active, further seismicity can be induced, regardless if the present stage is distant from the fault. However, the large events seem to occur in regions with a gap in the microseismicity. Interestingly, most of the seismicity is located above the reservoir, including the larger events. Although a shallow-well array is used, these results are believed to have relatively high depth resolution, as the perforation shots are correctly located with an average error of 26 m in depth. This information contradicts previously held views that large induced earthquakes occur primarily

  2. Constraining the Long-Term Average of Earthquake Recurrence Intervals From Paleo- and Historic Earthquakes by Assimilating Information From Instrumental Seismicity

    Science.gov (United States)

    Zoeller, G.

    2017-12-01

    Paleo- and historic earthquakes are the most important source of information for the estimationof long-term recurrence intervals in fault zones, because sequences of paleoearthquakes cover more than one seismic cycle. On the other hand, these events are often rare, dating uncertainties are enormous and the problem of missing or misinterpreted events leads to additional problems. Taking these shortcomings into account, long-term recurrence intervals are usually unstable as long as no additional information are included. In the present study, we assume that the time to the next major earthquake depends on the rate of small and intermediate events between the large ones in terms of a ``clock-change'' model that leads to a Brownian Passage Time distribution for recurrence intervals. We take advantage of an earlier finding that the aperiodicity of this distribution can be related to the Gutenberg-Richter-b-value, which is usually around one and can be estimated easily from instrumental seismicity in the region under consideration. This allows to reduce the uncertainties in the estimation of the mean recurrence interval significantly, especially for short paleoearthquake sequences and high dating uncertainties. We present illustrative case studies from Southern California and compare the method with the commonly used approach of exponentially distributed recurrence times assuming a stationary Poisson process.

  3. Application of a net-based baseline correction scheme to strong-motion records of the 2011 Mw 9.0 Tohoku earthquake

    Science.gov (United States)

    Tu, Rui; Wang, Rongjiang; Zhang, Yong; Walter, Thomas R.

    2014-06-01

    The description of static displacements associated with earthquakes is traditionally achieved using GPS, EDM or InSAR data. In addition, displacement histories can be derived from strong-motion records, allowing an improvement of geodetic networks at a high sampling rate and a better physical understanding of earthquake processes. Strong-motion records require a correction procedure appropriate for baseline shifts that may be caused by rotational motion, tilting and other instrumental effects. Common methods use an empirical bilinear correction on the velocity seismograms integrated from the strong-motion records. In this study, we overcome the weaknesses of an empirically based bilinear baseline correction scheme by using a net-based criterion to select the timing parameters. This idea is based on the physical principle that low-frequency seismic waveforms at neighbouring stations are coherent if the interstation distance is much smaller than the distance to the seismic source. For a dense strong-motion network, it is plausible to select the timing parameters so that the correlation coefficient between the velocity seismograms of two neighbouring stations is maximized after the baseline correction. We applied this new concept to the KiK-Net and K-Net strong-motion data available for the 2011 Mw 9.0 Tohoku earthquake. We compared the derived coseismic static displacement with high-quality GPS data, and with the results obtained using empirical methods. The results show that the proposed net-based approach is feasible and more robust than the individual empirical approaches. The outliers caused by unknown problems in the measurement system can be easily detected and quantified.

  4. A 667 year record of coseismic and interseismic Coulomb stress changes in central Italy reveals the role of fault interaction in controlling irregular earthquake recurrence intervals

    Science.gov (United States)

    Wedmore, L. N. J.; Faure Walker, J. P.; Roberts, G. P.; Sammonds, P. R.; McCaffrey, K. J. W.; Cowie, P. A.

    2017-07-01

    Current studies of fault interaction lack sufficiently long earthquake records and measurements of fault slip rates over multiple seismic cycles to fully investigate the effects of interseismic loading and coseismic stress changes on the surrounding fault network. We model elastic interactions between 97 faults from 30 earthquakes since 1349 A.D. in central Italy to investigate the relative importance of co-seismic stress changes versus interseismic stress accumulation for earthquake occurrence and fault interaction. This region has an exceptionally long, 667 year record of historical earthquakes and detailed constraints on the locations and slip rates of its active normal faults. Of 21 earthquakes since 1654, 20 events occurred on faults where combined coseismic and interseismic loading stresses were positive even though 20% of all faults are in "stress shadows" at any one time. Furthermore, the Coulomb stress on the faults that experience earthquakes is statistically different from a random sequence of earthquakes in the region. We show how coseismic Coulomb stress changes can alter earthquake interevent times by 103 years, and fault length controls the intensity of this effect. Static Coulomb stress changes cause greater interevent perturbations on shorter faults in areas characterized by lower strain (or slip) rates. The exceptional duration and number of earthquakes we model enable us to demonstrate the importance of combining long earthquake records with detailed knowledge of fault geometries, slip rates, and kinematics to understand the impact of stress changes in complex networks of active faults.

  5. Magnetic paleointensities recorded in fault pseudotachylytes and implications for earthquake lightnings

    Science.gov (United States)

    Leibovitz, Natalie; Ferré, Eric; Geissman, John; Gattacceca, Jérôme

    2015-04-01

    Fault pseudotachylytes commonly form by frictional melting due to seismic slip. These fine-grained clastic rocks result from melt quenching and may show a high concentration of fine ferromagnetic grains. These grains are potentially excellent recorders of the rock natural remanent magnetization (NRM). The magnetization processes of fault pseudotachylytes are complex and may include the following: i) near coseismic thermal remanent magnetization (TRM) acquired upon cooling of the melt; ii) coseismic lightning induced remanent magnetization (LIRM) caused by earthquake lightnings (EQL); iii) post seismic chemical remanent magnetization (CRM) related to both devitrification and alteration. Deciphering these magnetization components is crucial to the interpretation of microstructures and the timing of microstructural development. Hence the paleomagnetic record of fault pseudotachylytes provides an independent set of new constraints on coseismic and post-seismic deformation. Fault pseudotachylytes from the Santa Rosa Mountains, California host a magnetic assemblage dominated by stoichiometric magnetite, formed from the breakdown of ferromagnesian silicates and melt oxidation at high temperature. Magnetite grain size in these pseudotachylytes compares to that of magnetites formed in friction experiments. Paleomagnetic data on these 59 Ma-old fault rocks reveal not only anomalous magnetization directions, inconsistent with the coseismic geomagnetic field, but also anomalously high magnetization intensities. Here we discuss preliminary results of paleointensity experiments designed to quantify the intensity of coseismic magnetizing fields. The REM' paleointensity method is particularly well suited to investigate NRMs resulting from non-conventional and multiple magnetization processes. The anomalously high NRM recorded in a few, but not all, specimens points to LIRM as the dominant origin of magnetization.

  6. Low-cost coding of directivity information for the recording of musical instruments

    Science.gov (United States)

    Braasch, Jonas; Martens, William L.; Woszczyk, Wieslaw

    2004-05-01

    Most musical instruments radiate sound according to characteristic spatial directivity patterns. These patterns are usually not only strongly frequency dependent, but also time-variant functions of various parameters of the instrument, such as pitch and the playing technique applied (e.g., plucking versus bowing of string instruments). To capture the directivity information when recording an instrument, Warusfel and Misdariis (2001) proposed to record an instrument using four channels, one for the monopole and the others for three orthogonal dipole parts. In the new recording setup presented here, it is proposed to store one channel at a high sampling frequency, along with directivity information that is updated only every few milliseconds. Taking the binaural sluggishness of the human auditory system into account in this way provides a low-cost coding scheme for subsequent reproduction of time-variant directivity patterns.

  7. Establishment of data base of regional seismic recordings from earthquakes, chemical explosions and nuclear explosions in the Former Soviet Union

    Energy Technology Data Exchange (ETDEWEB)

    Ermolenko, N.A.; Kopnichev, Yu.F.; Kunakov, V.G.; Kunakova, O.K.; Rakhmatullin, M.Kh.; Sokolova, I.N.; Vybornyy, Zh.I. [AN SSSR, Moscow (Russian Federation). Inst. Fiziki Zemli

    1995-06-01

    In this report results of work on establishment of a data base of regional seismic recordings from earthquakes, chemical explosions and nuclear explosions in the former Soviet Union are described. This work was carried out in the Complex Seismological Expedition (CSE) of the Joint Institute of Physics of the Earth of the Russian Academy of Sciences and Lawrence Livermore National Laboratory. The recording system, methods of investigations and primary data processing are described in detail. The largest number of digital records was received by the permanent seismic station Talgar, situated in the northern Tien Shan, 20 km to the east of Almaty city. More than half of the records are seismograms of underground nuclear explosions and chemical explosions. The nuclear explosions were recorded mainly from the Semipalatinsk test site. In addition, records of the explosions from the Chinese test site Lop Nor and industrial nuclear explosions from the West Siberia region were obtained. Four records of strong chemical explosions were picked out (two of them have been produced at the Semipalatinsk test site and two -- in Uzbekistan). We also obtained 16 records of crustal earthquakes, mainly from the Altai region, close to the Semipalatinsk test site, and also from the West China region, close to the Lop Nor test site. In addition, a small number of records of earthquakes and underground nuclear explosions, received by arrays of temporary stations, that have been working in the southern Kazakhstan region are included in this report. Parameters of the digital seismograms and file structure are described. Possible directions of future work on the digitizing of unique data archive are discussed.

  8. The study of key issues about integration of GNSS and strong-motion records for real-time earthquake monitoring

    Science.gov (United States)

    Tu, Rui; Zhang, Pengfei; Zhang, Rui; Liu, Jinhai

    2016-08-01

    This paper has studied the key issues about integration of GNSS and strong-motion records for real-time earthquake monitoring. The validations show that the consistence of the coordinate system must be considered firstly to exclude the system bias between GNSS and strong-motion. The GNSS sampling rate is suggested about 1-5 Hz, and we should give the strong-motion's baseline shift with a larger dynamic noise as its variation is very swift. The initialization time of solving the baseline shift is less than one minute, and ambiguity resolution strategy is not greatly improved the solution. The data quality is very important for the solution, we advised to use multi-frequency and multi-system observations. These ideas give an important guide for real-time earthquake monitoring and early warning by the tight integration of GNSS and strong-motion records.

  9. Impact of earthquakes on agriculture during the Roman-Byzantine period from pollen records of the Dead Sea laminated sediment

    Science.gov (United States)

    Leroy, Suzanne A. G.; Marco, Shmuel; Bookman, Revital; Miller, Charlotte S.

    2010-03-01

    The Dead Sea region holds the archives of a complex relationship between an ever-changing nature and ancient civilisations. Regional pollen diagrams show a Roman-Byzantine period standing out in the recent millennia by its wetter climate that allowed intensive arboriculture. During that period, the Dead Sea formed laminites that display mostly a seasonal character. A multidisciplinary study focused on two earthquakes, 31 BC and AD 363, recorded as seismites in the Ze'elim gully A unit III which has been well dated by radiocarbon in a previous study. The sampling of the sediment was done at an annual resolution starting from a few years before and finishing a decade after each earthquake. A clear drop in agricultural indicators (especially Olea and cereals) is shown. These pollen indicators mostly reflect human activities in the Judean Hills and coastal oases. Agriculture was disturbed in large part of the rift valley where earthquake damage affected irrigation and access to the fields. It took 4 to 5 yr to resume agriculture to previous conditions. Earthquakes must be seen as contributors to factors damaging societies. If combined with other factors such as climatic aridification, disease epidemics and political upheaval, they may lead to civilisation collapse.

  10. Earthquake data base for Romania

    International Nuclear Information System (INIS)

    Rizescu, M.; Ghica, D.; Grecu, B.; Popa, M.; Borcia, I. S.

    2002-01-01

    A new earthquake database for Romania is being constructed, comprising complete earthquake information and being up-to-date, user-friendly and rapidly accessible. One main component of the database consists from the catalog of earthquakes occurred in Romania since 984 up to present. The catalog contains information related to locations and other source parameters, when available, and links to waveforms of important earthquakes. The other very important component is the 'strong motion database', developed for strong intermediate-depth Vrancea earthquakes where instrumental data were recorded. Different parameters to characterize strong motion properties as: effective peak acceleration, effective peak velocity, corner periods T c and T d , global response spectrum based intensities were computed and recorded into this database. Also, information on the recording seismic stations as: maps giving their positioning, photographs of the instruments and site conditions ('free-field or on buildings) are included. By the huge volume and quality of gathered data, also by its friendly user interface, the Romania earthquake data base provides a very useful tool for geosciences and civil engineering in their effort towards reducing seismic risk in Romania. (authors)

  11. Earthquake Catalogue of the Caucasus

    Science.gov (United States)

    Godoladze, T.; Gok, R.; Tvaradze, N.; Tumanova, N.; Gunia, I.; Onur, T.

    2016-12-01

    The Caucasus has a documented historical catalog stretching back to the beginning of the Christian era. Most of the largest historical earthquakes prior to the 19th century are assumed to have occurred on active faults of the Greater Caucasus. Important earthquakes include the Samtskhe earthquake of 1283 (Ms˜7.0, Io=9); Lechkhumi-Svaneti earthquake of 1350 (Ms˜7.0, Io=9); and the Alaverdi earthquake of 1742 (Ms˜6.8, Io=9). Two significant historical earthquakes that may have occurred within the Javakheti plateau in the Lesser Caucasus are the Tmogvi earthquake of 1088 (Ms˜6.5, Io=9) and the Akhalkalaki earthquake of 1899 (Ms˜6.3, Io =8-9). Large earthquakes that occurred in the Caucasus within the period of instrumental observation are: Gori 1920; Tabatskuri 1940; Chkhalta 1963; Racha earthquake of 1991 (Ms=7.0), is the largest event ever recorded in the region; Barisakho earthquake of 1992 (M=6.5); Spitak earthquake of 1988 (Ms=6.9, 100 km south of Tbilisi), which killed over 50,000 people in Armenia. Recently, permanent broadband stations have been deployed across the region as part of the various national networks (Georgia (˜25 stations), Azerbaijan (˜35 stations), Armenia (˜14 stations)). The data from the last 10 years of observation provides an opportunity to perform modern, fundamental scientific investigations. In order to improve seismic data quality a catalog of all instrumentally recorded earthquakes has been compiled by the IES (Institute of Earth Sciences/NSMC, Ilia State University) in the framework of regional joint project (Armenia, Azerbaijan, Georgia, Turkey, USA) "Probabilistic Seismic Hazard Assessment (PSHA) in the Caucasus. The catalogue consists of more then 80,000 events. First arrivals of each earthquake of Mw>=4.0 have been carefully examined. To reduce calculation errors, we corrected arrivals from the seismic records. We improved locations of the events and recalculate Moment magnitudes in order to obtain unified magnitude

  12. Strong Motion Network of Medellín and Aburrá Valley: technical advances, seismicity records and micro-earthquake monitoring

    Science.gov (United States)

    Posada, G.; Trujillo, J. C., Sr.; Hoyos, C.; Monsalve, G.

    2017-12-01

    The tectonics setting of Colombia is determined by the interaction of Nazca, Caribbean and South American plates, together with the Panama-Choco block collision, which makes a seismically active region. Regional seismic monitoring is carried out by the National Seismological Network of Colombia and the Accelerometer National Network of Colombia. Both networks calculate locations, magnitudes, depths and accelerations, and other seismic parameters. The Medellín - Aburra Valley is located in the Northern segment of the Central Cordillera of Colombia, and according to the Colombian technical seismic norm (NSR-10), is a region of intermediate hazard, because of the proximity to seismic sources of the Valley. Seismic monitoring in the Aburra Valley began in 1996 with an accelerometer network which consisted of 38 instruments. Currently, the network consists of 26 stations and is run by the Early Warning System of Medellin and Aburra Valley (SIATA). The technical advances have allowed the real-time communication since a year ago, currently with 10 stations; post-earthquake data is processed through operationally near-real-time, obtaining quick results in terms of location, acceleration, spectrum response and Fourier analysis; this information is displayed at the SIATA web site. The strong motion database is composed by 280 earthquakes; this information is the basis for the estimation of seismic hazards and risk for the region. A basic statistical analysis of the main information was carried out, including the total recorded events per station, natural frequency, maximum accelerations, depths and magnitudes, which allowed us to identify the main seismic sources, and some seismic site parameters. With the idea of a more complete seismic monitoring and in order to identify seismic sources beneath the Valley, we are in the process of installing 10 low-cost shake seismometers for micro-earthquake monitoring. There is no historical record of earthquakes with a magnitude

  13. Paleoseismic Records of 1762 and Similar Prior Earthquakes Along the South-Eastern Coast of Bangladesh

    Science.gov (United States)

    Mondal, D. R.; McHugh, C. M.; Mortlock, R. A.; Gurung, D.; Bastas-Hernandez, A.; Steckler, M. S.; Seeber, L.; Mustaque, S.; Goodbred, S. L., Jr.; Akhter, S. H.; Saha, P.

    2014-12-01

    The great 1762 Arakan earthquake caused subsidence and uplift along 700km of the Arakan coast, and is thought to derive from a huge megathrust rupture reaching northward onto the southeastern coast of Bangladesh. Paleoseismic investigations were conducted in that area to document effects of that and prior earthquakes. U/Th ages obtained from isochron analysis of uplifted dead coral heads of the Poritesspecies, collected along a south to north transect from the islands east coast reveal at least three growth interruptions caused by abrupt relative sea-level changes within the past 1300 years that we interpret to be associated with megathrust ruptures. The ages show distinct events approximately 250, 900 and 1300 years ago. The youngest of these events corresponds to the 1762 Great Arakan earthquake. The two prior events at ~1100 and 700 AD, suggest an average recurrence interval of 400-600 years. Along the coast of Teknaf, we mapped a ~2m uplifted terrace. Marine shells on top of the terrace dated with C-14 at 1695-1791 AD link the uplift to the 1762 Great Arakan earthquake. Based on this evidence and previous work (Wang et al., 2013 and Aung et al., 2008), we estimated the 1762 rupture to be at least 700 km long, from Chebuda Island to the Sitakund anticline encompassing the Teknaf Peninsula. Considering 14 mm/yr convergence rate and 400-600 yrs recurrence interval, this rupture zone has now accumulated elastic deformation to generate a M~8.4 earthquake, close to the M8.8 estimated by Cummins (2007) for the 1762 earthquake. Published recurrence intervals based on C-14 ages along the Myanmar coast ~90 km south of Bangladesh reveal three ruptures within the last 3400 years with an average recurrence interval of 1000-2000 years (Aung et al., 2008). While the 1762 rupture reached across both areas, some of the prior ruptures may be confined to one or the other of these areas, with a smaller magnitude. Our precise U-Th ages provide evidence of recurrence intervals of

  14. Co-seismic strain changes of Wenchuan Mw7. 9 earthquake recorded by borehole strainmeters on Tibetan plateau

    Directory of Open Access Journals (Sweden)

    Fu Guangyu

    2011-08-01

    Full Text Available Co-seismic strain changes of the Wenchuan Mw7. 9 earthquake recorded with three four-component borehole strainmeters showed NW-SE and roughly EW extensions, respectively, at two locations in the interior and northern part of Tibetan plateau, and NS shortening at a location south of the epicenter, in agreement with the tectonic stress field of this region. The observed values of as much as 10−7 are, however, larger than theoretical values obtained with half-space and spherical-earth dislocation theories, implying the existence of other effects, such as local crustal structure and initial stress.

  15. Intermediate-Depth Subduction Earthquakes Recorded by Pseudotachylyte in Dry Eclogite-Facies Oceanic Lithosphere from the Alps

    Science.gov (United States)

    Scambelluri, M.; Pennacchioni, G.; Gilio, M.; Bestmann, M.

    2016-12-01

    While geophysical studies and laboratory experiments provide much information on subduction earthquakes, field studies identifying the rock types for earthquake development and the deep seismogenic environments are still scarce. To date, fluid overpressure and volume decrease during hydrous mineral breakdown the widely favoured trigger of subduction earthquakes in serpentinized lithospheric mantle and hydrated low-velocity layers atop slabs. Here we document up to 40 cm-thick pseudotachylyte (PST) in Alpine oceanic gabbro and peridotite (2-2.5 GPa-550-620°C), the analogue of a modern cold subducting oceanic lithosphere. These rocks mostly remained unaltered dry systems; only very minor domains (<1%) record partial hydration and static eclogitic metamorphism. Meta-peridotite shows high-pressure olivine + antigorite (garnet + zoisite + chlorite after mantle plagioclase); meta-gabbro develops omphacite + zoisite + talc + chloritoid + garnet. Abundant syn-eclogitic pseudotachylyte cut the dry gabbro-peridotite and the eclogitized domains. In meta-peridotite, PST shows olivine, orthopyroxene, spinel microliths and clasts of high-pressure olivine + antigorite and garnet + zoisite + chlorite aggregates. In metagabbro, microfaults in damage zones near PST cut brecciated igneous pyroxene cemented by omphacite. In unaltered gabbro, glassy PST contains micron-scale garnet replacing plagioclase microliths during, or soon after, PST cooling. In the host rock, garnet coronas between igneous olivine and plagioclase only occur near PST and between closely spaced PST veins. Absence of garnet away from PST indicates that garnet growth was triggered by mineral seeds and by heat released by PST. The above evidence shows that pseudotachylyte formed at eclogite-facies conditions. In such setting, strong, dry, metastable gabbro-peridotite concentrate stress to generate large intermediate depth subduction earthquakes without much involvement of free fluid.

  16. Ionospheric density variations recorded before the 2010 Mw 8.8 earthquake in Chile

    Czech Academy of Sciences Publication Activity Database

    Píša, David; Parrot, M.; Santolík, Ondřej

    2011-01-01

    Roč. 116, - (2011), A08309/1-A08309/8 ISSN 0148-0227 R&D Projects: GA MŠk ME09107 Institutional research plan: CEZ:AV0Z30420517 Keywords : DEMETER satellite * pre- seismic activity * Offshore Bio-bio earthquake Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.021, year: 2011 http://www.agu.org/pubs/crossref/2011/2011JA016611.shtml

  17. Real-time seismic monitoring of the integrated cape girardeau bridge array and recorded earthquake response

    Science.gov (United States)

    Celebi, M.

    2006-01-01

    This paper introduces the state of the art, real-time and broad-band seismic monitoring network implemented for the 1206 m [3956 ft] long, cable-stayed Bill Emerson Memorial Bridge in Cape Girardeau (MO), a new Mississippi River crossing, approximately 80 km from the epicentral region of the 1811-1812 New Madrid earthquakes. The bridge was designed for a strong earthquake (magnitude 7.5 or greater) during the design life of the bridge. The monitoring network comprises a total of 84 channels of accelerometers deployed on the superstructure, pier foundations and at surface and downhole free-field arrays of the bridge. The paper also presents the high quality response data obtained from the network. Such data is aimed to be used by the owner, researchers and engineers to assess the performance of the bridge, to check design parameters, including the comparison of dynamic characteristics with actual response, and to better design future similar bridges. Preliminary analyses of ambient and low amplitude small earthquake data reveal specific response characteristics of the bridge and the free-field. There is evidence of coherent tower, cable, deck interaction that sometimes results in amplified ambient motions. Motions at the lowest tri-axial downhole accelerometers on both MO and IL sides are practically free from any feedback from the bridge. Motions at the mid-level and surface downhole accelerometers are influenced significantly by feedback due to amplified ambient motions of the bridge. Copyright ASCE 2006.

  18. Analog earthquakes

    International Nuclear Information System (INIS)

    Hofmann, R.B.

    1995-01-01

    Analogs are used to understand complex or poorly understood phenomena for which little data may be available at the actual repository site. Earthquakes are complex phenomena, and they can have a large number of effects on the natural system, as well as on engineered structures. Instrumental data close to the source of large earthquakes are rarely obtained. The rare events for which measurements are available may be used, with modfications, as analogs for potential large earthquakes at sites where no earthquake data are available. In the following, several examples of nuclear reactor and liquified natural gas facility siting are discussed. A potential use of analog earthquakes is proposed for a high-level nuclear waste (HLW) repository

  19. OMG Earthquake! Can Twitter improve earthquake response?

    Science.gov (United States)

    Earle, P. S.; Guy, M.; Ostrum, C.; Horvath, S.; Buckmaster, R. A.

    2009-12-01

    such as epicenter, magnitude, and strong-motion recordings. Without quantitative data, prioritization of response measures, including building and infrastructure inspection, are not possible. The main advantage of Twitter is speed, especially in sparsely instrumented areas. A Twitter based system potentially could provide a quick notification that there was a possible event and that seismographically derived information will follow. If you are interested in learning more, follow @USGSted on Twitter.

  20. A method for automating calibration and records management for instrumentation and dosimetry

    International Nuclear Information System (INIS)

    O'Brien, J.M. Jr.; Rushton, R.O.; Burns, R.E. Jr.

    1993-01-01

    Current industry requirements are becoming more stringent on quality assurance records and documentation for calibration of instruments and dosimetry. A novel method is presented here that will allow a progressive automation scheme to be used in pursuit of that goal. This concept is based on computer-controlled irradiators that can act as stand-alone devices or be interfaced to other components via a computer local area network. In this way, complete systems can be built with modules to create a records management system to meet the needs of small laboratories or large multi-building calibration groups. Different database engines or formats can be used simply by replacing a module. Modules for temperature and pressure monitoring or shipping and receiving can be added, as well as equipment modules for direct IEEE-488 interface to electrometers and other instrumentation

  1. A method for automating calibration and records management for instrumentation and dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    O`Brien, J.M. Jr.; Rushton, R.O.; Burns, R.E. Jr. [Atlan-Tech, Inc., Roswell, GA (United States)

    1993-12-31

    Current industry requirements are becoming more stringent on quality assurance records and documentation for calibration of instruments and dosimetry. A novel method is presented here that will allow a progressive automation scheme to be used in pursuit of that goal. This concept is based on computer-controlled irradiators that can act as stand-alone devices or be interfaced to other components via a computer local area network. In this way, complete systems can be built with modules to create a records management system to meet the needs of small laboratories or large multi-building calibration groups. Different database engines or formats can be used simply by replacing a module. Modules for temperature and pressure monitoring or shipping and receiving can be added, as well as equipment modules for direct IEEE-488 interface to electrometers and other instrumentation.

  2. Upper-plate splay fault earthquakes along the Arakan subduction belt recorded by uplifted coral microatolls on northern Ramree Island, western Myanmar (Burma)

    Science.gov (United States)

    Shyu, J. Bruce H.; Wang, Chung-Che; Wang, Yu; Shen, Chuan-Chou; Chiang, Hong-Wei; Liu, Sze-Chieh; Min, Soe; Aung, Lin Thu; Than, Oo; Tun, Soe Thura

    2018-02-01

    Upper-plate structures that splay out from the megathrusts are common features along major convergent plate boundaries. However, their earthquake and tsunami hazard potentials have not yet received significant attention. In this study, we identified at least one earthquake event that may have been produced by an upper-plate splay fault offshore western Myanmar, based on U-Th ages of uplifted coral microatolls. This event is likely an earthquake that was documented historically in C.E. 1848, with an estimated magnitude between 6.8 and 7.2 based on regional structural characteristics. Such magnitude is consistent with the observed co-seismic uplift amount of ∼0.5 m. Although these events are smaller in magnitude than events produced by megathrusts, they may produce higher earthquake and tsunami hazards for local coastal communities due to their proximity. Our results also indicate that earthquake events with co-seismic uplift along the coast may not necessarily produce a flight of marine terraces. Therefore, using only records of uplifted marine terraces as megathrust earthquake proxies may overlook the importance of upper-plate splay fault ruptures, and underestimate the overall earthquake frequency for future seismic and tsunami hazards along major subduction zones of the world.

  3. The Earthquakes Role in the Paleoenviromental Record of the Lakes and in the Development of the Mesoamerican Cultures

    Science.gov (United States)

    Garduño Monroy, V. H., Sr.; Israde-Alcantara, I.

    2017-12-01

    Inside the Mexican Volcanic Belt Paleoseismological and Archeoseismological studies in the lakes sedimentary sequences delimited by seismically active faults are of importance. Those studies reveal that the lakes can not be analyzed only in the context of climatic variations or anthropogenic effects. The lakes of the ancient Tenochtitlan, Cuitzeo, Pátzcuaro, Zacapu in Michoacán (Tarascan Culture) and Zacoalco and Juanacatlán in Jalisco (Cultures of the West of Mexico) testimoniate throughout their sedimentation record, extraordinary seismic events that modified the geometry of the strata, sedimentation rates, and the morphology of the lakes bottom, among others. In some cases, these events were seen as premonitories of some misfortune "the fifth omen of the arrival of the Spaniards was the fact that the water surrounded Tenochtitlan rose with great waves that traveled far away, entering into the houses, shaking its foundations and making them fall". All these effects generated by important earthquakes like liquefaction, faulting, slumps, folding among others, have been studied in cores obtained in the mentioned lakes. Seismic events are observed in different stratigraphic levels, and with the 14C datation it is possible to obtain the recurrence of seismic events (M> 5). The Mesoamerican cultures developed very clear concepts about the earthquakes intensities, mixing earth (tlalli) and movement (ollin) symbols. However, much of this information has been omitted in the interpretation of secondary structures generated by earthquakes with M> 5. These phenomens modified the paleoenvironmental conditions on the lakes of central Mexico, in the context of intraplate faults oriented optimally into the late Holoce field stress.

  4. Extending the Instrumental Record of Sea-Level Change: A 1300-Year Sea-Level Record From Eastern Connecticut

    Science.gov (United States)

    Donnelly, J. P.; Cleary, P.

    2002-12-01

    The instrumental record of sea-level change in the northeastern United States extends back to the early 20th century and at New York City (NYC) extends back to 1856. These tide gauge records indicate that sea level has risen at a rate of 2.5 to 4 mm/year over the last 100-150 years. Geologic evidence of sea-level change in the region over the last 2,000 years indicates rates of sea-level rise of about 1 mm/year or less. The discordance between the instrumental and geologic records is frequently cited as potentially providing evidence that anthropogenic warming of the climate system has resulted in an increase in the rate of sea-level rise. In order to begin to test the hypothesis that acceleration in the rate of sea-level rise has occurred in the last 150 years due to anthropogenic climate warming, accurate and precise information on the timing of the apparent acceleration in sea-level rise are needed. Here we construct a high-resolution relative sea-level record for the past 1350 years by dating basal salt marsh peat samples above a glacial erratic in a western Connecticut salt marsh. Preservation of marsh vegetation remains in the sediment record that has a narrow vertical habitat range at the upper end of the tidal range provides information on past sea levels. { \\it Spartina patens} (marsh hay) and { \\it Juncus gerardi} (black rush) dominate both the modern marsh and their remains are the major constituent of the marsh sediments and occur in the modern marsh between mean high water (MHW) and mean highest high water. We use the elevation distribution of modern plant communities to estimate the relationship of sediment samples to paleo-mean high water. The chronology is based on 15 radiocarbon ages, supplemented by age estimates derived from the horizons of industrial Pb pollution and pollen indicative of European land clearance. Thirteen of the radiocarbon ages and the Pb and pollen data come from samples taken along a contact between marsh peat and a glacial

  5. The October 1992 Parkfield, California, earthquake prediction

    Science.gov (United States)

    Langbein, J.

    1992-01-01

    A magnitude 4.7 earthquake occurred near Parkfield, California, on October 20, 992, at 05:28 UTC (October 19 at 10:28 p.m. local or Pacific Daylight Time).This moderate shock, interpreted as the potential foreshock of a damaging earthquake on the San Andreas fault, triggered long-standing federal, state and local government plans to issue a public warning of an imminent magnitude 6 earthquake near Parkfield. Although the predicted earthquake did not take place, sophisticated suites of instruments deployed as part of the Parkfield Earthquake Prediction Experiment recorded valuable data associated with an unusual series of events. this article describes the geological aspects of these events, which occurred near Parkfield in October 1992. The accompnaying article, an edited version of a press conference b Richard Andrews, the Director of the California Office of Emergency Service (OES), describes governmental response to the prediction.   

  6. Snpp CrIS Instrumental Status and Raw Data Record Quality Since the Mission

    Science.gov (United States)

    Jin, X.; Han, Y.; Sun, N.; Weng, F.; Wang, L.; Chen, Y.; Tremblay, D. A.

    2014-12-01

    The SNPP CrIS (cross-track infrared sounder) has been in service for more than two years. As the first operational interferometric hyper-spectral sounder onboard the new-generation polar-orbit meteorological satellite, CrIS's instrumental performance and data quality are widely concerned. NOAA/NESDIS/STAR CrIS Cal/Val team have been actively involved since the beginning of the mission. An intact record of the CrIS instrumental performance and raw data record (RDR) has been established. In this presentation, the continuous records of some critical indicators such as noise, gain, laser wavelength drifting and many other parameters related to the internal thermal status, are presented. It is found that the hardware performance is extremely stable in the past two years and the degradation is very small. These features make CrIS a great candidate for long-term climate studies. Moreover, the completeness of RDR data is another advantage of taking CrIS for climate studies. NOAA/NESDIS/STAR has recorded all of the CrIS RDR data since the launch and has been dedicated to improving the data quality.

  7. Analysis of debris-flow recordings in an instrumented basin: confirmations and new findings

    Directory of Open Access Journals (Sweden)

    M. Arattano

    2012-03-01

    Full Text Available On 24 August 2006, a debris flow took place in the Moscardo Torrent, a basin of the Eastern Italian Alps instrumented for debris-flow monitoring. The debris flow was recorded by two seismic networks located in the lower part of the basin and on the alluvial fan, respectively. The event was also recorded by a pair of ultrasonic sensors installed on the fan, close to the lower seismic network. The comparison between the different recordings outlines particular features of the August 2006 debris flow, different from that of events recorded in previous years. A typical debris-flow wave was observed at the upper seismic network, with a main front abruptly appearing in the torrent, followed by a gradual decrease of flow height. On the contrary, on the alluvial fan the wave displayed an irregular pattern, with low flow depth and the main peak occurring in the central part of the surge both in the seismic recording and in the hydrographs. Recorded data and field evidences indicate that the surge observed on the alluvial fan was not a debris flow, and probably consisted in a water surge laden with fine to medium-sized sediment. The change in shape and characteristics of the wave can be ascribed to the attenuation of the surge caused by the torrent control works implemented in the lower basin during the last years.

  8. Nineteenth Century Long-Term Instrumental Records, Examples From the Southeastern United States

    Science.gov (United States)

    Mock, C. J.

    2001-12-01

    Early instrumental records in the United States, defined as those operating before 1892 which is regarded the period prior to the modern climate record, provide a longer perspective of climatic variability at decadal and interannual timescales. Such reconstructions also provide a means of verification for other proxy data. This paper provides a American perspective of historical climatic research, emphasizing the urgent need to properly evaluate data quality and provide necessary corrections to make them compatible with the modern record. Different fixed observation times, different practices of weather instrument exposures, and statistical methods for calibration are the main issues in applying corrections and conducting proper climatic interpretations. I illustrate several examples on methodologies of this historical climatic research, focusing on the following in the Southeastern United States: daily reconstructed temperature time-series centered on Charleston SC and Natchez MS back to the late eighteenth century, and precipitation frequency reconstructions during the antebellum period for the Gulf Coast and coastal Southeast Atlantic states. Results indicate several prominent extremes unprecedented as compared to the modern record, such as the widespread warm winter of 1827-28, and the severe cold winters of 1856 and 1857. The reconstructions also yield important information concerning responses to past ENSO events, the PNA, NAO, and the PDO, particularly when compared with instrumental data from other regions. A high potential also exists for applying the climate reconstructions to assess historical climatic impacts on society in the Southeast, such as to understand climatic linkages to famous case studies of Yellow Fever epidemics and severe drought.

  9. Improvement of geological subsurface structure models for Kanto area, Japan, based on records of microtremor array and earthquake observations

    Science.gov (United States)

    Wakai, A.; Senna, S.; Jin, K.; Cho, I.; Matsuyama, H.; Fujiwara, H.

    2017-12-01

    To estimate damage caused by strong ground motions from a large earthquake, it is important to accurately evaluate broadband ground-motion characteristics in wide area. For realizing that, it is one of the important issues to model detailed subsurface structure from top surface of seismic bedrock to ground surface.Here, we focus on Kanto area, including Tokyo, where there are thicker sedimentary layers. We, first, have ever collected deep bore-hole data, soil physical properties obtained by some geophysical explorations, geological information and existing models for deep ground from top surface of seismic bedrock to that of engineering bedrock, and have collected a great number of bore-hole data and surficial geological ones for shallow ground from top surface of engineering bedrock to ground surface. Using them, we modeled initial geological subsurface structure for each of deep ground and shallow one. By connecting them appropriately, we constructed initial geological subsurface structure models from top surface of seismic bedrock to ground surface.In this study, we first collected a lot of records obtained by dense microtremor observations and earthquake ones in the whole Kanto area. About microtremor observations, we conducted measurements from large array with the size of hundreds of meters to miniature array with the size of 60 centimeters to cover both of deep ground and shallow one. And then, using ground motion characteristics such as disperse curves and H/V(R/V) spectral ratios obtained from these records, the initial geological subsurface structure models were improved in terms of velocity structure from top surface of seismic bedrock to ground surface in the area.We will report outlines on microtremor array observations, analysis methods and improved subsurface structure models.

  10. Instrumentation for low noise nanopore-based ionic current recording under laser illumination

    Science.gov (United States)

    Roelen, Zachary; Bustamante, José A.; Carlsen, Autumn; Baker-Murray, Aidan; Tabard-Cossa, Vincent

    2018-01-01

    We describe a nanopore-based optofluidic instrument capable of performing low-noise ionic current recordings of individual biomolecules under laser illumination. In such systems, simultaneous optical measurements generally introduce significant parasitic noise in the electrical signal, which can severely reduce the instrument sensitivity, critically hindering the monitoring of single-molecule events in the ionic current traces. Here, we present design rules and describe simple adjustments to the experimental setup to mitigate the different noise sources encountered when integrating optical components to an electrical nanopore system. In particular, we address the contributions to the electrical noise spectra from illuminating the nanopore during ionic current recording and mitigate those effects through control of the illumination source and the use of a PDMS layer on the SiNx membrane. We demonstrate the effectiveness of our noise minimization strategies by showing the detection of DNA translocation events during membrane illumination with a signal-to-noise ratio of ˜10 at 10 kHz bandwidth. The instrumental guidelines for noise minimization that we report are applicable to a wide range of nanopore-based optofluidic systems and offer the possibility of enhancing the quality of synchronous optical and electrical signals obtained during single-molecule nanopore-based analysis.

  11. Source Rupture Process of the 2016 Kumamoto, Japan, Earthquake Inverted from Strong-Motion Records

    Science.gov (United States)

    Zhang, Wenbo; Zheng, Ao

    2017-04-01

    On 15 April, 2016 the great earthquake with magnitude Mw7.1 occurred in Kumamoto prefecture, Japan. The focal mechanism solution released by F-net located the hypocenter at 130.7630°E, 32.7545°N, at a depth of 12.45 km, and the strike, dip, and the rake angle of the fault were N226°E, 84˚ and -142° respectively. The epicenter distribution and focal mechanisms of aftershocks implied the mechanism of the mainshock might have changed in the source rupture process, thus a single focal mechanism was not enough to explain the observed data adequately. In this study, based on the inversion result of GNSS and InSAR surface deformation with active structures for reference, we construct a finite fault model with focal mechanism changes, and derive the source rupture process by multi-time-window linear waveform inversion method using the strong-motion data (0.05 1.0Hz) obtained by K-NET and KiK-net of Japan. Our result shows that the Kumamoto earthquake is a right-lateral strike slipping rupture event along the Futagawa-Hinagu fault zone, and the seismogenic fault is divided into a northern segment and a southern one. The strike and the dip of the northern segment are N235°E, 60˚ respectively. And for the southern one, they are N205°E, 72˚ respectively. The depth range of the fault model is consistent with the depth distribution of aftershocks, and the slip on the fault plane mainly concentrate on the northern segment, in which the maximum slip is about 7.9 meter. The rupture process of the whole fault continues for approximately 18-sec, and the total seismic moment released is 5.47×1019N·m (Mw 7.1). In addition, the essential feature of the distribution of PGV and PGA synthesized by the inversion result is similar to that of observed PGA and seismic intensity.

  12. Flood rich periods, flood poor periods and the need to look beyond instrumental records

    Science.gov (United States)

    Lane, S. N.

    2009-04-01

    For many, the later 20th Century and early 21st Century has become synonymous with a growing experience of flood risk. Scientists, politicians and the media have ascribed this to changing climate and there are good hypothetical reasons for human-induced climate change to be impacting upon the magnitude and frequency of extreme weather events. In this paper, I will interrogate this claim more carefully, using the UK's instrumental records of river flow, most of which begin after 1960, but a smaller number of which extend back into the 19th Century. Those records that extent back to the 19th Century suggest that major flood events tend to cluster into periods that are relatively flood rich and relatively flood poor, most notably in larger drainage basins: i.e. there is a clear scale issue. The timing (inset, duration, termination) of these periods varies systematically by region although there is a marked flood poor period for much of the UK during the late 1960s, 1970s and 1980s. It follows that at least some of the current experience of flooding, including why it has taken so many policy-makers and flood victims by surprise, may reflect a transition from a flood poor to a flood rich period, exacerbated by possible climate change impacts. These results point to the need to rethink how we think through what drives flood risk. First, it points to the need to look at some of the fundamental oscillations in core atmospheric drivers, such as the North Atlantic Multidecadal Oscillation, in explaining what drives flood risk. Consideration of precipitation, as opposed to river flow, is more advanced in this respect, and those of us working in rivers need to engage much more thoughtfully with atmospheric scientists. Second, it points to the severe inadequacies in using records of only a few decades duration. Even where these are pooled across adjacent sub-catchments, there is likely to be a severe bias in the estimation of flood return periods when we look at instrumental

  13. Practical guidelines to select and scale earthquake records for nonlinear response history analysis of structures

    Science.gov (United States)

    Kalkan, Erol; Chopra, Anil K.

    2010-01-01

    Earthquake engineering practice is increasingly using nonlinear response history analysis (RHA) to demonstrate performance of structures. This rigorous method of analysis requires selection and scaling of ground motions appropriate to design hazard levels. Presented herein is a modal-pushover-based scaling (MPS) method to scale ground motions for use in nonlinear RHA of buildings and bridges. In the MPS method, the ground motions are scaled to match (to a specified tolerance) a target value of the inelastic deformation of the first-'mode' inelastic single-degree-of-freedom (SDF) system whose properties are determined by first-'mode' pushover analysis. Appropriate for first-?mode? dominated structures, this approach is extended for structures with significant contributions of higher modes by considering elastic deformation of second-'mode' SDF system in selecting a subset of the scaled ground motions. Based on results presented for two bridges, covering single- and multi-span 'ordinary standard' bridge types, and six buildings, covering low-, mid-, and tall building types in California, the accuracy and efficiency of the MPS procedure are established and its superiority over the ASCE/SEI 7-05 scaling procedure is demonstrated.

  14. Fault failure with moderate earthquakes

    Science.gov (United States)

    Johnston, M. J. S.; Linde, A. T.; Gladwin, M. T.; Borcherdt, R. D.

    1987-12-01

    High resolution strain and tilt recordings were made in the near-field of, and prior to, the May 1983 Coalinga earthquake ( ML = 6.7, Δ = 51 km), the August 4, 1985, Kettleman Hills earthquake ( ML = 5.5, Δ = 34 km), the April 1984 Morgan Hill earthquake ( ML = 6.1, Δ = 55 km), the November 1984 Round Valley earthquake ( ML = 5.8, Δ = 54 km), the January 14, 1978, Izu, Japan earthquake ( ML = 7.0, Δ = 28 km), and several other smaller magnitude earthquakes. These recordings were made with near-surface instruments (resolution 10 -8), with borehole dilatometers (resolution 10 -10) and a 3-component borehole strainmeter (resolution 10 -9). While observed coseismic offsets are generally in good agreement with expectations from elastic dislocation theory, and while post-seismic deformation continued, in some cases, with a moment comparable to that of the main shock, preseismic strain or tilt perturbations from hours to seconds (or less) before the main shock are not apparent above the present resolution. Precursory slip for these events, if any occurred, must have had a moment less than a few percent of that of the main event. To the extent that these records reflect general fault behavior, the strong constraint on the size and amount of slip triggering major rupture makes prediction of the onset times and final magnitudes of the rupture zones a difficult task unless the instruments are fortuitously installed near the rupture initiation point. These data are best explained by an inhomogeneous failure model for which various areas of the fault plane have either different stress-slip constitutive laws or spatially varying constitutive parameters. Other work on seismic waveform analysis and synthetic waveforms indicates that the rupturing process is inhomogeneous and controlled by points of higher strength. These models indicate that rupture initiation occurs at smaller regions of higher strength which, when broken, allow runaway catastrophic failure.

  15. Musical instrument recordings made with a fiber Fabry-Perot cavity: photonic guitar pickup.

    Science.gov (United States)

    Ballard, Nicholas; Paz-Soldan, Daniel; Kung, Peter; Loock, Hans-Peter

    2010-04-10

    A 1 cm long, low-finesse fiber-optic cavity was used as a transducer for the vibrations of the soundboard of an acoustic guitar and of a violin. The reflected light is detected and then amplified and recorded using conventional audio instrumentation. The fiber-optic pickup is found to have a high response range in both amplitude (up to 100 microm displacement) and audio frequency (DC to 20 kHz) and good linearity up to a displacement of 225 microm. The audio noise is found to arise from the fiber-optic cables and, to a lesser extent, from the laser and laser driver.

  16. Remotely Triggered Earthquakes Recorded by EarthScope's Transportable Array and Regional Seismic Networks: A Case Study Of Four Large Earthquakes

    Science.gov (United States)

    Velasco, A. A.; Cerda, I.; Linville, L.; Kilb, D. L.; Pankow, K. L.

    2013-05-01

    Changes in field stress required to trigger earthquakes have been classified in two basic ways: static and dynamic triggering. Static triggering occurs when an earthquake that releases accumulated strain along a fault stress loads a nearby fault. Dynamic triggering occurs when an earthquake is induced by the passing of seismic waves from a large mainshock located at least two or more fault lengths from the epicenter of the main shock. We investigate details of dynamic triggering using data collected from EarthScope's USArray and regional seismic networks located in the United States. Triggered events are identified using an optimized automated detector based on the ratio of short term to long term average (Antelope software). Following the automated processing, the flagged waveforms are individually analyzed, in both the time and frequency domains, to determine if the increased detection rates correspond to local earthquakes (i.e., potentially remotely triggered aftershocks). Here, we show results using this automated schema applied to data from four large, but characteristically different, earthquakes -- Chile (Mw 8.8 2010), Tokoku-Oki (Mw 9.0 2011), Baja California (Mw 7.2 2010) and Wells Nevada (Mw 6.0 2008). For each of our four mainshocks, the number of detections within the 10 hour time windows span a large range (1 to over 200) and statistically >20% of the waveforms show evidence of anomalous signals following the mainshock. The results will help provide for a better understanding of the physical mechanisms involved in dynamic earthquake triggering and will help identify zones in the continental U.S. that may be more susceptible to dynamic earthquake triggering.

  17. A multi-functional testing instrument for heat assisted magnetic recording media

    International Nuclear Information System (INIS)

    Yang, H. Z.; Chen, Y. J.; Leong, S. H.; An, C. W.; Ye, K. D.; Hu, J. F.; Yin, M. J.

    2014-01-01

    With recent developments in heat assisted magnetic recording (HAMR), characterization of HAMR media is becoming very important. We present a multi-functional instrument for testing HAMR media, which integrates HAMR writing, reading, and a micro-magneto-optic Kerr effect (μ-MOKE) testing function. A potential application of the present instrument is to make temperature dependent magnetic property measurement using a pump-probe configuration. In the measurement, the media is heated up by a heating (intense) beam while a testing (weak) beam is overlapped with the heating beam for MOKE measurement. By heating the media with different heating beam power, magnetic measurements by MOKE at different temperatures can be performed. Compared to traditional existing tools such as the vibrating sample magnetometer, the present instrument provides localized and efficient heating at the measurement spot. The integration of HAMR writing and μ-MOKE system can also facilitate a localized full investigation of the magnetic media by potential correlation of HAMR head independent write/read performance to localized magnetic properties

  18. Can Vrancea earthquakes be accurately predicted from unusual bio-system behavior and seismic-electromagnetic records?

    International Nuclear Information System (INIS)

    Enescu, D.; Chitaru, C.; Enescu, B.D.

    1999-01-01

    The relevance of bio-seismic research for the short-term prediction of strong Vrancea earthquakes is underscored. An unusual animal behavior before and during Vrancea earthquakes is described and illustrated in the individual case of the major earthquake of March 4, 1977. Several hypotheses to account for the uncommon behavior of bio-systems in relation to earthquakes in general and strong Vrancea earthquakes in particular are discussed in the second section. It is reminded that promising preliminary results concerning the identification of seismic-electromagnetic precursor signals have been obtained in the Vrancea seismogenic area using special, highly sensitive equipment. The need to correlate bio-seismic and seismic-electromagnetic researches is evident. Further investigations are suggested and urgent steps are proposed in order to achieve a successful short-term prediction of strong Vrancea earthquakes. (authors)

  19. Simple procedure for evaluating earthquake response spectra of large-event motions based on site amplification factors derived from smaller-event records

    International Nuclear Information System (INIS)

    Dan, Kazuo; Miyakoshi, Jun-ichi; Yashiro, Kazuhiko.

    1996-01-01

    A primitive procedure was proposed for evaluating earthquake response spectra of large-event motions to make use of records from smaller events. The result of the regression analysis of the response spectra was utilized to obtain the site amplification factors in the proposed procedure, and the formulation of the seismic-source term in the regression analysis was examined. A linear form of the moment magnitude, Mw, is good for scaling the source term of moderate earthquakes with Mw of 5.5 to 7.0, while a quadratic form of Mw and the ω-square source-spectrum model is appropriate for scaling the source term of smaller and greater earthquakes, respectively. (author). 52 refs

  20. Natural Language Processing Based Instrument for Classification of Free Text Medical Records

    Directory of Open Access Journals (Sweden)

    Manana Khachidze

    2016-01-01

    Full Text Available According to the Ministry of Labor, Health and Social Affairs of Georgia a new health management system has to be introduced in the nearest future. In this context arises the problem of structuring and classifying documents containing all the history of medical services provided. The present work introduces the instrument for classification of medical records based on the Georgian language. It is the first attempt of such classification of the Georgian language based medical records. On the whole 24.855 examination records have been studied. The documents were classified into three main groups (ultrasonography, endoscopy, and X-ray and 13 subgroups using two well-known methods: Support Vector Machine (SVM and K-Nearest Neighbor (KNN. The results obtained demonstrated that both machine learning methods performed successfully, with a little supremacy of SVM. In the process of classification a “shrink” method, based on features selection, was introduced and applied. At the first stage of classification the results of the “shrink” case were better; however, on the second stage of classification into subclasses 23% of all documents could not be linked to only one definite individual subclass (liver or binary system due to common features characterizing these subclasses. The overall results of the study were successful.

  1. Instrumentation

    International Nuclear Information System (INIS)

    Prieur, G.; Nadi, M.; Hedjiedj, A.; Weber, S.

    1995-01-01

    This second chapter on instrumentation gives little general consideration on history and classification of instrumentation, and two specific states of the art. The first one concerns NMR (block diagram of instrumentation chain with details on the magnets, gradients, probes, reception unit). The first one concerns precision instrumentation (optical fiber gyro-meter and scanning electron microscope), and its data processing tools (programmability, VXI standard and its history). The chapter ends with future trends on smart sensors and Field Emission Displays. (D.L.). Refs., figs

  2. A study of relay, breaker, instrumentation and control failures during an earthquake, and their effect on nuclear power plant safety

    International Nuclear Information System (INIS)

    Lambert, H.E.; Budnitz, R.J.

    1987-01-01

    In this project, an improved PRA systems analysis methodology for post-earthquake relay-chatter analysis is developed, and its use is demonstrated through analysis of the Zion-1 and LaSalle-2 reactors as case studies. For both Zion-1 and LaSalle-2, assuming that loss of offsite power (LOSP) occurs after a large earthquake and that there are no operator recovery actions, the analysis finds very many combinations (Boolean minimal cut sets) involving chatter of three or four relays and/or pressure switch contacts. The number is so large that there is a very high likelihood (of the order of unity) that at least one combination will occur after earthquake-caused LOSP. This conclusion depends in detail on the fragility curves and response assumptions used for chatter. (orig.)

  3. Instrumentation

    International Nuclear Information System (INIS)

    Decreton, M.

    2000-01-01

    SCK-CEN's research and development programme on instrumentation aims at evaluating the potentials of new instrumentation technologies under the severe constraints of a nuclear application. It focuses on the tolerance of sensors to high radiation doses, including optical fibre sensors, and on the related intelligent data processing needed to cope with the nuclear constraints. Main achievements in these domains in 1999 are summarised

  4. Instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Decreton, M

    2001-04-01

    SCK-CEN's research and development programme on instrumentation involves the assessment and the development of sensitive measurement systems used within a radiation environment. Particular emphasis is on the assessment of optical fibre components and their adaptability to radiation environments. The evaluation of ageing processes of instrumentation in fission plants, the development of specific data evaluation strategies to compensate for ageing induced degradation of sensors and cable performance form part of these activities. In 2000, particular emphasis was on in-core reactor instrumentation applied to fusion, accelerator driven and water-cooled fission reactors. This involved the development of high performance instrumentation for irradiation experiments in the BR2 reactor in support of new instrumentation needs for MYRRHA, and for diagnostic systems for the ITER reactor.

  5. Instrumentation

    International Nuclear Information System (INIS)

    Decreton, M.

    2001-01-01

    SCK-CEN's research and development programme on instrumentation involves the assessment and the development of sensitive measurement systems used within a radiation environment. Particular emphasis is on the assessment of optical fibre components and their adaptability to radiation environments. The evaluation of ageing processes of instrumentation in fission plants, the development of specific data evaluation strategies to compensate for ageing induced degradation of sensors and cable performance form part of these activities. In 2000, particular emphasis was on in-core reactor instrumentation applied to fusion, accelerator driven and water-cooled fission reactors. This involved the development of high performance instrumentation for irradiation experiments in the BR2 reactor in support of new instrumentation needs for MYRRHA, and for diagnostic systems for the ITER reactor

  6. Foraminiferal record of Holocene paleo-earthquakes on the subsiding south-western Poverty Bay coastline, New Zealand

    International Nuclear Information System (INIS)

    Hayward, B.W.; Sabaa, A.T.; Grenfell, H.R.; Cochran, U.A.; Clark, K.J.; Litchfield, N.J.; Wallace, L.M.; Marden, M.; Palmer, A.S.

    2015-01-01

    Foraminiferal faunas in 29 short cores (maximum depth 7 m) of estuarine and coastal wetland sediment were used to reconstruct the middle-late Holocene (last 7 ka) elevational history on the southern shores of Poverty Bay, North Island, New Zealand. This coast is on the southwest side of a rapidly subsiding area beneath western Poverty Bay. Modern Analogue Technique paleo-elevation estimates based on fossil foraminiferal faunas indicate that the four study areas have gradual late Holocene (<3.5 ka) subsidence rates that increase from the southwest (mean c. 0.5 m ka - - 1 ) to northeast (mean c. 1.0 m ka -1 ). Only two rapid, possibly co-seismic, vertical displacement events are recognised: (1) c. 1.2 m of subsidence at 5.7 ± 0.4 ka (cal yr BP), which may have been generated by a subduction interface earthquake centred offshore and recorded in other published studies in northern Hawkes Bay, c. 35 km to the south; and (2) c. 1 m of uplift (relative sea-level fall) at c. 4.5 ± 0.3 ka, which might have been generated by rupture on an offshore upper plate fault that also uplifted coastal terraces at Pakarae and Mahia, 40 km to the north and south of the study area, or by rupture on the subduction interface penetrating beneath Poverty Bay. No sudden displacement events are recognised during the last 4 ka although subsidence, possibly aseismic, has continued. (author).

  7. Crowdsourced earthquake early warning

    Science.gov (United States)

    Minson, Sarah E.; Brooks, Benjamin A.; Glennie, Craig L.; Murray, Jessica R.; Langbein, John O.; Owen, Susan E.; Heaton, Thomas H.; Iannucci, Robert A.; Hauser, Darren L.

    2015-01-01

    Earthquake early warning (EEW) can reduce harm to people and infrastructure from earthquakes and tsunamis, but it has not been implemented in most high earthquake-risk regions because of prohibitive cost. Common consumer devices such as smartphones contain low-cost versions of the sensors used in EEW. Although less accurate than scientific-grade instruments, these sensors are globally ubiquitous. Through controlled tests of consumer devices, simulation of an Mw (moment magnitude) 7 earthquake on California’s Hayward fault, and real data from the Mw 9 Tohoku-oki earthquake, we demonstrate that EEW could be achieved via crowdsourcing.

  8. Earthquake Facts

    Science.gov (United States)

    ... North Dakota, and Wisconsin. The core of the earth was the first internal structural element to be identified. In 1906 R.D. Oldham discovered it from his studies of earthquake records. The inner core is solid, and the outer core is liquid and so does not transmit ...

  9. Understanding Earthquakes

    Science.gov (United States)

    Davis, Amanda; Gray, Ron

    2018-01-01

    December 26, 2004 was one of the deadliest days in modern history, when a 9.3 magnitude earthquake--the third largest ever recorded--struck off the coast of Sumatra in Indonesia (National Centers for Environmental Information 2014). The massive quake lasted at least 10 minutes and devastated the Indian Ocean. The quake displaced an estimated…

  10. Instrumentation

    International Nuclear Information System (INIS)

    Decreton, M.

    2002-01-01

    SCK-CEN's R and D programme on instrumentation involves the development of advanced instrumentation systems for nuclear applications as well as the assessment of the performance of these instruments in a radiation environment. Particular emphasis is on the use of optical fibres as umbilincal links of a remote handling unit for use during maintanance of a fusion reacor, studies on the radiation hardening of plasma diagnostic systems; investigations on new instrumentation for the future MYRRHA accelerator driven system; space applications related to radiation-hardened lenses; the development of new approaches for dose, temperature and strain measurements; the assessment of radiation-hardened sensors and motors for remote handling tasks and studies of dose measurement systems including the use of optical fibres. Progress and achievements in these areas for 2001 are described

  11. Instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Decreton, M

    2002-04-01

    SCK-CEN's R and D programme on instrumentation involves the development of advanced instrumentation systems for nuclear applications as well as the assessment of the performance of these instruments in a radiation environment. Particular emphasis is on the use of optical fibres as umbilincal links of a remote handling unit for use during maintanance of a fusion reacor, studies on the radiation hardening of plasma diagnostic systems; investigations on new instrumentation for the future MYRRHA accelerator driven system; space applications related to radiation-hardened lenses; the development of new approaches for dose, temperature and strain measurements; the assessment of radiation-hardened sensors and motors for remote handling tasks and studies of dose measurement systems including the use of optical fibres. Progress and achievements in these areas for 2001 are described.

  12. Instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Decreton, M

    2000-07-01

    SCK-CEN's research and development programme on instrumentation aims at evaluating the potentials of new instrumentation technologies under the severe constraints of a nuclear application. It focuses on the tolerance of sensors to high radiation doses, including optical fibre sensors, and on the related intelligent data processing needed to cope with the nuclear constraints. Main achievements in these domains in 1999 are summarised.

  13. Instrumentation

    International Nuclear Information System (INIS)

    Umminger, K.

    2008-01-01

    A proper measurement of the relevant single and two-phase flow parameters is the basis for the understanding of many complex thermal-hydraulic processes. Reliable instrumentation is therefore necessary for the interaction between analysis and experiment especially in the field of nuclear safety research where postulated accident scenarios have to be simulated in experimental facilities and predicted by complex computer code systems. The so-called conventional instrumentation for the measurement of e. g. pressures, temperatures, pressure differences and single phase flow velocities is still a solid basis for the investigation and interpretation of many phenomena and especially for the understanding of the overall system behavior. Measurement data from such instrumentation still serves in many cases as a database for thermal-hydraulic system codes. However some special instrumentation such as online concentration measurement for boric acid in the water phase or for non-condensibles in steam atmosphere as well as flow visualization techniques were further developed and successfully applied during the recent years. Concerning the modeling needs for advanced thermal-hydraulic codes, significant advances have been accomplished in the last few years in the local instrumentation technology for two-phase flow by the application of new sensor techniques, optical or beam methods and electronic technology. This paper will give insight into the current state of instrumentation technology for safety-related thermohydraulic experiments. Advantages and limitations of some measurement processes and systems will be indicated as well as trends and possibilities for further development. Aspects of instrumentation in operating reactors will also be mentioned.

  14. US earthquake observatories: recommendations for a new national network

    Energy Technology Data Exchange (ETDEWEB)

    1980-01-01

    This report is the first attempt by the seismological community to rationalize and optimize the distribution of earthquake observatories across the United States. The main aim is to increase significantly our knowledge of earthquakes and the earth's dynamics by providing access to scientifically more valuable data. Other objectives are to provide a more efficient and cost-effective system of recording and distributing earthquake data and to make as uniform as possible the recording of earthquakes in all states. The central recommendation of the Panel is that the guiding concept be established of a rationalized and integrated seismograph system consisting of regional seismograph networks run for crucial regional research and monitoring purposes in tandem with a carefully designed, but sparser, nationwide network of technologically advanced observatories. Such a national system must be thought of not only in terms of instrumentation but equally in terms of data storage, computer processing, and record availability.

  15. Characteristics of fin whale vocalizations recorded on instruments in the northeast Pacific Ocean

    Science.gov (United States)

    Weirathmueller, Maria Michelle Josephine

    This thesis focuses on fin whale vocalizations recorded on ocean bottom seismometers (OBSs) in the Northeast Pacific Ocean, using data collected between 2003 and 2013. OBSs are a valuable, and largely untapped resource for the passive acoustic monitoring of large baleen whales. This dissertation is divided into three parts, each of which uses the recordings of fin whale vocalizations to better understand their calling behaviors and distributions. The first study describes the development of a technique to extract source levels of fin whale vocalizations from OBS recordings. Source levels were estimated using data collected on a network of eight OBSs in the Northeast Pacific Ocean. The acoustic pressure levels measured at the instruments were adjusted for the propagation path between the calling whales and the instruments using the call location and estimating losses along the acoustic travel path. A total of 1241 calls were used to estimate an average source level of 189 +/-5.8 dB re 1uPa 1m. This variability is largely attributed to uncertainties in the horizontal and vertical position of the fin whale at the time of each call, and the effect of these uncertainties on subsequent calculations. The second study describes a semi-automated method for obtaining horizontal ranges to vocalizing fin whales using the timing and relative amplitude of multipath arrivals. A matched filter is used to detect fin whale calls and pick the relative times and amplitudes of multipath arrivals. Ray-based propagation models are used to predict multipath times and amplitudes as function of range. Because the direct and first multiple arrivals are not always observed, three hypotheses for the paths of the observed arrivals are considered; the solution is the hypothesis and range that optimizes the fit to the data. Ray-theoretical amplitudes are not accurate and solutions are improved by determining amplitudes from the observations using a bootstrap method. Data from ocean bottom

  16. Ground water and earthquakes

    Energy Technology Data Exchange (ETDEWEB)

    Ts' ai, T H

    1977-11-01

    Chinese folk wisdom has long seen a relationship between ground water and earthquakes. Before an earthquake there is often an unusual change in the ground water level and volume of flow. Changes in the amount of particulate matter in ground water as well as changes in color, bubbling, gas emission, and noises and geysers are also often observed before earthquakes. Analysis of these features can help predict earthquakes. Other factors unrelated to earthquakes can cause some of these changes, too. As a first step it is necessary to find sites which are sensitive to changes in ground stress to be used as sensor points for predicting earthquakes. The necessary features are described. Recording of seismic waves of earthquake aftershocks is also an important part of earthquake predictions.

  17. Evaluation and optimization of seismic networks and algorithms for earthquake early warning – the case of Istanbul (Turkey)

    OpenAIRE

    Oth, Adrien; Böse, Maren; Wenzel, Friedemann; Köhler, Nina; Erdik, Mustafa

    2010-01-01

    Earthquake early warning (EEW) systems should provide reliable warnings as quickly as possible with a minimum number of false and missed alarms. Using the example of the megacity Istanbul and based on a set of simulated scenario earthquakes, we present a novel approach for evaluating and optimizing seismic networks for EEW, in particular in regions with a scarce number of instrumentally recorded earthquakes. We show that, while the current station locations of the existing Istanbul EEW system...

  18. Instruments

    International Nuclear Information System (INIS)

    Buehrer, W.

    1996-01-01

    The present paper mediates a basic knowledge of the most commonly used experimental techniques. We discuss the principles and concepts necessary to understand what one is doing if one performs an experiment on a certain instrument. (author) 29 figs., 1 tab., refs

  19. The Challenge of Centennial Earthquakes to Improve Modern Earthquake Engineering

    International Nuclear Information System (INIS)

    Saragoni, G. Rodolfo

    2008-01-01

    The recent commemoration of the centennial of the San Francisco and Valparaiso 1906 earthquakes has given the opportunity to reanalyze their damages from modern earthquake engineering perspective. These two earthquakes plus Messina Reggio Calabria 1908 had a strong impact in the birth and developing of earthquake engineering. The study of the seismic performance of some up today existing buildings, that survive centennial earthquakes, represent a challenge to better understand the limitations of our in use earthquake design methods. Only Valparaiso 1906 earthquake, of the three considered centennial earthquakes, has been repeated again as the Central Chile, 1985, Ms = 7.8 earthquake. In this paper a comparative study of the damage produced by 1906 and 1985 Valparaiso earthquakes is done in the neighborhood of Valparaiso harbor. In this study the only three centennial buildings of 3 stories that survived both earthquakes almost undamaged were identified. Since for 1985 earthquake accelerogram at El Almendral soil conditions as well as in rock were recoded, the vulnerability analysis of these building is done considering instrumental measurements of the demand. The study concludes that good performance of these buildings in the epicentral zone of large earthquakes can not be well explained by modern earthquake engineering methods. Therefore, it is recommended to use in the future of more suitable instrumental parameters, such as the destructiveness potential factor, to describe earthquake demand

  20. Seismic Instrumentation Placement Recommendations Report

    International Nuclear Information System (INIS)

    Kennedy, W.N.

    1998-01-01

    DOE Order 420.1, ''Facility Safety'', requires that facilities or sites with hazardous materials be provided with instrumentation or other means to detect and record the occurrences and severity of seismic events. These requirements assure that necessary records are available after an earthquake for evaluation purposes and to supplement other data to justify a facility restart or curtailing plant operations after an earthquake. This report documents the basis for the selection of Savannah River Site areas and existing facilities to be instrumented. The need to install instrumentation in new facilities such as the Actinide Packaging and Storage Facility, Commercial Light Water Reactor Tritium Extraction Facility and the Accelerator Production of Tritium Facility will be assessed separately

  1. Sound production in recorder-like instruments : II. a simulation model

    NARCIS (Netherlands)

    Verge, M.P.; Hirschberg, A.; Causse, R.

    1997-01-01

    A simple one-dimensional representation of recorderlike instruments, that can be used for sound synthesis by physical modeling of flutelike instruments, is presented. This model combines the effects on the sound production by the instrument of the jet oscillations, vortex shedding at the edge of the

  2. Consistency of GPS and strong-motion records: case study of the Mw9.0 Tohoku-Oki 2011 earthquake

    Science.gov (United States)

    Psimoulis, Panos; Houlié, Nicolas; Michel, Clotaire; Meindl, Michael; Rothacher, Markus

    2014-05-01

    High-rate GPS data are today commonly used to supplement seismic data for the Earth surface motions focusing on earthquake characterisation and rupture modelling. Processing of GPS records using Precise Point Positioning (PPP) can provide real-time information of seismic wave propagation, tsunami early-warning and seismic rupture. Most studies have shown differences between the GPS and seismic systems at very long periods (e.g. >100sec) and static displacements. The aim of this study is the assessment of the consistency of GPS and strong-motion records by comparing their respective displacement waveforms for several frequency bands. For this purpose, the records of the GPS (GEONET) and the strong-motion (KiK-net and K-NET) networks corresponding to the Mw9.0 Tohoku 2011 earthquake were analysed. The comparison of the displacement waveforms of collocated (distance<100m) GPS and strong-motion sites show that the consistency between the two datasets depends on the frequency of the excitation. Differences are mainly due to the GPS noise at relatively short-periods (<3-4 s) and the saturation of the strong-motion sensors for relatively long-periods (40-80 s). Furthermore the agreement between the GPS and strong-motion records also depends on the direction of the excitation signal and the distance from the epicentre. In conclusion, velocities and displacements recovered from GPS and strong-motion records are consistent for long-periods (3-100 s), proving that GPS networks can contribute to the real-time estimation of the long-period ground motion map of an earthquake.

  3. Instrumentation

    International Nuclear Information System (INIS)

    Muehllehner, G.; Colsher, J.G.

    1982-01-01

    This chapter reviews the parameters which are important to positron-imaging instruments. It summarizes the options which various groups have explored in designing tomographs and the methods which have been developed to overcome some of the limitations inherent in the technique as well as in present instruments. The chapter is not presented as a defense of positron imaging versus single-photon or other imaging modality, neither does it contain a description of various existing instruments, but rather stresses their common properties and problems. Design parameters which are considered are resolution, sampling requirements, sensitivity, methods of eliminating scattered radiation, random coincidences and attenuation. The implementation of these parameters is considered, with special reference to sampling, choice of detector material, detector ring diameter and shielding and variations in point spread function. Quantitation problems discussed are normalization, and attenuation and random corrections. Present developments mentioned are noise reduction through time-of-flight-assisted tomography and signal to noise improvements through high intrinsic resolution. Extensive bibliography. (U.K.)

  4. Distribution of incremental static stress caused by earthquakes

    Directory of Open Access Journals (Sweden)

    Y. Y. Kagan

    1994-01-01

    Full Text Available Theoretical calculations, simulations and measurements of rotation of earthquake focal mechanisms suggest that the stress in earthquake focal zones follows the Cauchy distribution which is one of the stable probability distributions (with the value of the exponent α equal to 1. We review the properties of the stable distributions and show that the Cauchy distribution is expected to approximate the stress caused by earthquakes occurring over geologically long intervals of a fault zone development. However, the stress caused by recent earthquakes recorded in instrumental catalogues, should follow symmetric stable distributions with the value of α significantly less than one. This is explained by a fractal distribution of earthquake hypocentres: the dimension of a hypocentre set, ��, is close to zero for short-term earthquake catalogues and asymptotically approaches 2¼ for long-time intervals. We use the Harvard catalogue of seismic moment tensor solutions to investigate the distribution of incremental static stress caused by earthquakes. The stress measured in the focal zone of each event is approximated by stable distributions. In agreement with theoretical considerations, the exponent value of the distribution approaches zero as the time span of an earthquake catalogue (ΔT decreases. For large stress values α increases. We surmise that it is caused by the δ increase for small inter-earthquake distances due to location errors.

  5. Impact of the Atlantic Multidecadal Oscillation (AMO) on deriving anthropogenic warming rates from the instrumental temperature record

    NARCIS (Netherlands)

    van der Werf, G.R.; Dolman, A.J.

    2014-01-01

    The instrumental surface air temperature record has been used in several statistical studies to assess the relative role of natural and anthropogenic drivers of climate change. The results of those studies varied considerably, with anthropogenic temperature trends over the past 25-30 years suggested

  6. Testing earthquake source inversion methodologies

    KAUST Repository

    Page, Morgan T.; Mai, Paul Martin; Schorlemmer, Danijel

    2011-01-01

    Source Inversion Validation Workshop; Palm Springs, California, 11-12 September 2010; Nowadays earthquake source inversions are routinely performed after large earthquakes and represent a key connection between recorded seismic and geodetic data

  7. Statistical evaluation of recorded knowledge in nuclear and other instrumental analytical techniques

    International Nuclear Information System (INIS)

    Braun, T.

    1987-01-01

    The main points addressed in this study are the following: Statistical distribution patterns of published literature on instrumental analytical techniques 1981-1984; structure of scientific literature and heuristics for identifying active specialities and emerging hot spot research areas in instrumental analytical techniques; growth and growth rates of the literature in some of the identified hot research areas; quality and quantity in instrumental analytical research output. (orig.)

  8. Radon, gas geochemistry, groundwater, and earthquakes

    Energy Technology Data Exchange (ETDEWEB)

    King, Chi-Yu [Power Reactor and Nuclear Fuel Development Corp., Tono Geoscience Center, Toki, Gifu (Japan)

    1998-12-31

    Radon monitoring in groundwater, soil air, and atmosphere has been continued in many seismic areas of the world for earthquake-prediction and active-fault studies. Some recent measurements of radon and other geochemical and hydrological parameters have been made for sufficiently long periods, with reliable instruments, and together with measurements of meteorological variables and solid-earth tides. The resultant data are useful in better distinguishing earthquake-related changes from various background noises. Some measurements have been carried out in areas where other geophysical measurements are being made also. Comparative studies of various kinds of geophysical data are helpful in ascertaining the reality of the earthquake-related and fault-related anomalies and in understanding the underlying mechanisms. Spatial anomalies of radon and other terrestrial gasses have been observed for many active faults. Such observations indicate that gas concentrations are very much site dependent, particularly on fault zones where terrestrial fluids may move vertically. Temporal anomalies have been reliably observed before and after some recent earthquakes, including the 1995 Kobe earthquake, and the general pattern of anomaly occurrence remains the same as observed before: They are recorded at only relatively few sensitive sites, which can be at much larger distances than expected from existing earthquake-source models. The sensitivity of a sensitive site is also found to be changeable with time. These results clearly show the inadequacy of the existing dilatancy-fluid diffusion and elastic-dislocation models for earthquake sources to explain earthquake-related geochemical and geophysical changes recorded at large distances. (J.P.N.)

  9. Effects on atmospherics at 6 kHz and 9 kHz recorded at Tripura during the India-Pakistan Border earthquake

    Directory of Open Access Journals (Sweden)

    S. S. De

    2010-04-01

    Full Text Available The outcome of the results of some analyses of electromagnetic emissions recorded by VLF receivers at 6 kHz and 9 kHz over Agartala, Tripura, the North-Eastern state of India (Lat. 23° N, Long. 91.4° E during the large earthquake at Muzaffarabad (Lat. 34.53° N, Long. 73.58° E at Kashmir under Pakistan have been presented here. Spiky variations in integrated field intensity of atmospherics (IFIA at 6 and 9 kHz have been observed 10 days prior (from midnight of 28 September 2005 to the day of occurrence of the earthquake on 8 October 2005 and the effect continued, decayed gradually and eventually ceased on 16 October 2005. The spikes distinctly superimposed on the ambient level with mutual separation of 2–5 min. Occurrence number of spikes per hour and total duration of their occurrence have been found remarkably high on the day of occurrence of the earthquake. The spike heights are higher at 6 kHz than at 9 kHz. The results have been explained on the basis of generation of electromagnetic radiation associated with fracture of rocks, their subsequent penetration into the Earth's atmosphere and finally their propagation between Earth-ionosphere waveguide. The present observation shows that VLF anomaly is well-confined between 6 and 9 kHz.

  10. Estimation of 1-D velocity models beneath strong-motion observation sites in the Kathmandu Valley using strong-motion records from moderate-sized earthquakes

    Science.gov (United States)

    Bijukchhen, Subeg M.; Takai, Nobuo; Shigefuji, Michiko; Ichiyanagi, Masayoshi; Sasatani, Tsutomu; Sugimura, Yokito

    2017-07-01

    The Himalayan collision zone experiences many seismic activities with large earthquakes occurring at certain time intervals. The damming of the proto-Bagmati River as a result of rapid mountain-building processes created a lake in the Kathmandu Valley that eventually dried out, leaving thick unconsolidated lacustrine deposits. Previous studies have shown that the sediments are 600 m thick in the center. A location in a seismically active region, and the possible amplification of seismic waves due to thick sediments, have made Kathmandu Valley seismically vulnerable. It has suffered devastation due to earthquakes several times in the past. The development of the Kathmandu Valley into the largest urban agglomerate in Nepal has exposed a large population to seismic hazards. This vulnerability was apparent during the Gorkha Earthquake (Mw7.8) on April 25, 2015, when the main shock and ensuing aftershocks claimed more than 1700 lives and nearly 13% of buildings inside the valley were completely damaged. Preparing safe and up-to-date building codes to reduce seismic risk requires a thorough study of ground motion amplification. Characterizing subsurface velocity structure is a step toward achieving that goal. We used the records from an array of strong-motion accelerometers installed by Hokkaido University and Tribhuvan University to construct 1-D velocity models of station sites by forward modeling of low-frequency S-waves. Filtered records (0.1-0.5 Hz) from one of the accelerometers installed at a rock site during a moderate-sized (mb4.9) earthquake on August 30, 2013, and three moderate-sized (Mw5.1, Mw5.1, and Mw5.5) aftershocks of the 2015 Gorkha Earthquake were used as input motion for modeling of low-frequency S-waves. We consulted available geological maps, cross-sections, and borehole data as the basis for initial models for the sediment sites. This study shows that the basin has an undulating topography and sediment sites have deposits of varying thicknesses

  11. Listening to the 2011 magnitude 9.0 Tohoku-Oki, Japan, earthquake

    Science.gov (United States)

    Peng, Zhigang; Aiken, Chastity; Kilb, Debi; Shelly, David R.; Enescu, Bogdan

    2012-01-01

    The magnitude 9.0 Tohoku-Oki, Japan, earthquake on 11 March 2011 is the largest earthquake to date in Japan’s modern history and is ranked as the fourth largest earthquake in the world since 1900. This earthquake occurred within the northeast Japan subduction zone (Figure 1), where the Pacific plate is subducting beneath the Okhotsk plate at rate of ∼8–9 cm/yr (DeMets et al. 2010). This type of extremely large earthquake within a subduction zone is generally termed a “megathrust” earthquake. Strong shaking from this magnitude 9 earthquake engulfed the entire Japanese Islands, reaching a maximum acceleration ∼3 times that of gravity (3 g). Two days prior to the main event, a foreshock sequence occurred, including one earthquake of magnitude 7.2. Following the main event, numerous aftershocks occurred around the main slip region; the largest of these was magnitude 7.9. The entire foreshocks-mainshock-aftershocks sequence was well recorded by thousands of sensitive seismometers and geodetic instruments across Japan, resulting in the best-recorded megathrust earthquake in history. This devastating earthquake resulted in significant damage and high death tolls caused primarily by the associated large tsunami. This tsunami reached heights of more than 30 m, and inundation propagated inland more than 5 km from the Pacific coast, which also caused a nuclear crisis that is still affecting people’s lives in certain regions of Japan.

  12. Strong-motion characteristics and source process during the Suruga Bay earthquake in 2009 through observed records on rock sites

    International Nuclear Information System (INIS)

    Shiba, Yoshiaki; Sato, Hiroaki; Kuriyama, Masayuki

    2010-01-01

    On 11 August 2009, a moderate earthquake of M 6.5 occurred in the Suruga Bay region, south of Shizuoka prefecture. During this event, JMA Seismic Intensity reached 6 lower in several cities around the hypocenter, and at Hamaoka nuclear power plant of Chubu Electric Power reactors were automatically shutdown due to large ground motions. Though the epicenter is located at the eastern edge of source area for the assumed great Tokai earthquake of M 8, this event is classified into the intra-plate (intra-slab) earthquake, due to its focal depth lower than that of the plate boundary and fault geometry supposed from the moment tensor solution. Dense strong-motion observation network has been deployed mainly on the rock outcrops by our institute around the source area, and the waveform data of the main shock and several aftershocks were obtained at 13 stations within 100 km from the hypocenter. The observed peak ground motions and velocity response spectral amplitudes are both obviously larger than the empirical attenuation relations derived from the inland and plate-boundary earthquake data, which displays the characteristics of the intra-slab earthquake faulting. Estimated acceleration source spectra of the main shock also exhibit the short period level about 1.7 times larger than the average of those for past events, and it corresponds with the additional term in the attenuation curve of the peak ground acceleration for the intra-plate earthquake. Detailed source process of the main shock is inferred using the inversion technique. The initial source model is assumed to be composed of two distinct fault planes according to the minute aftershock distribution. Estimated source model shows that large slip occurred near the hypocenter and at the boundary region between two fault planes where the rupture transfers from primary to secondary fault. Furthermore the broadband source inversion using velocity motions in the frequency up to 5 Hz demonstrates the high effective

  13. Instrumental shaking thresholds for seismically induced landslides and preliminary report on landslides triggered by the October 17, 1989, Loma Prieta, California earthquake

    Science.gov (United States)

    Harp, E.L.

    1993-01-01

    The generation of seismically induced landslide depends on the characteristics of shaking as well as mechanical properties of geologic materials. A very important parameter in the study of seismically induced landslide is the intensity based on a strong-motion accelerogram: it is defined as Arias intensity and is proportional to the duration of the shaking record as well as the amplitude. Having a theoretical relationship between Arias intensity, magnitude and distance it is possible to predict how far away from the seismic source landslides are likely to occur for a given magnitude earthquake. Field investigations have established that the threshold level of Arias intensity depends also on site effects, particularly the fracture characteristics of the outcrops present. -from Author

  14. Correspondence between audio and visual deep models for musical instrument detection in video recordings

    OpenAIRE

    Slizovskaia, Olga; Gómez, Emilia; Haro, Gloria

    2017-01-01

    This work aims at investigating cross-modal connections between audio and video sources in the task of musical instrument recognition. We also address in this work the understanding of the representations learned by convolutional neural networks (CNNs) and we study feature correspondence between audio and visual components of a multimodal CNN architecture. For each instrument category, we select the most activated neurons and investigate exist- ing cross-correlations between neurons from the ...

  15. Estimation of S-wave velocity structure of deep sedimentary layers using geophysical data and earthquake ground motion records

    International Nuclear Information System (INIS)

    Suzuki, Haruhiko

    2014-01-01

    The preliminary results with an outline of array observation for micro-tremor and natural earthquakes around the NIIT site were explained. Phase velocity estimated from a horizontal array of strong motion observation agrees with that from the micro-tremor survey. Estimation results are consistent with other literature, such as PS-logging data and gravity maps. Further improvement of the three-dimensional modeling by using micro-tremor surveys and horizontal array observation is planned for the future. (author)

  16. Investigating correlations between earthquakes and extreme eventsin self-potential data recorded in a seismicarea of Southestern Appennine Chain (Italy

    Directory of Open Access Journals (Sweden)

    V. Lapenna

    2004-06-01

    Full Text Available The Normalized Wavelet Cross-Correlation Function (NWCCF was used to study correlations between the series of extreme events in self-potential data and earthquakes, both modelled as stochastic point processes. This method gives objective results, robust to the presence of nonstationarities that often affect observational time series. Furthermore, the NWCCF identifies the timescales involved in the cross-correlated behaviour between two point processes. In particular, we analyzed the cross-correlation between the sequence of extreme events in selfpotential data measured at the monitoring station Tito, located in a seismic area of Southern Italy, and the series of earthquakes which occurred in the same area during 2001. To evaluate the influence of rain on the dynamics of geoelectrical variations, we applied the same approach between the selected extreme values and the rain data. We find that the anomalous geoelectrical values seem to cross-correlate with the rain at short and intermediate timescales (t< 500 h, while they significantly cross-correlate only with earthquakes (M = 2.5 at long timescales (t> 500 h.

  17. Far-field tsunami of 2017 Mw 8.1 Tehuantepec, Mexico earthquake recorded by Chilean tide gauge network: Implications for tsunami warning systems

    Science.gov (United States)

    González-Carrasco, J. F.; Benavente, R. F.; Zelaya, C.; Núñez, C.; Gonzalez, G.

    2017-12-01

    The 2017 Mw 8.1, Tehuantepec earthquake generated a moderated tsunami, which was registered in near-field tide gauges network activating a tsunami threat state for Mexico issued by PTWC. In the case of Chile, the forecast of tsunami waves indicate amplitudes less than 0.3 meters above the tide level, advising an informative state of threat, without activation of evacuation procedures. Nevertheless, during sea level monitoring of network we detect wave amplitudes (> 0.3 m) indicating a possible change of threat state. Finally, NTWS maintains informative level of threat based on mathematical filtering analysis of sea level records. After 2010 Mw 8.8, Maule earthquake, the Chilean National Tsunami Warning System (NTWS) has increased its observational capabilities to improve early response. Most important operational efforts have focused on strengthening tide gauge network for national area of responsibility. Furthermore, technological initiatives as Integrated Tsunami Prediction and Warning System (SIPAT) has segmented the area of responsibility in blocks to focus early warning and evacuation procedures on most affected coastal areas, while maintaining an informative state for distant areas of near-field earthquake. In the case of far-field events, NTWS follow the recommendations proposed by Pacific Tsunami Warning Center (PTWC), including a comprehensive monitoring of sea level records, such as tide gauges and DART (Deep-Ocean Assessment and Reporting of Tsunami) buoys, to evaluate the state of tsunami threat in the area of responsibility. The main objective of this work is to analyze the first-order physical processes involved in the far-field propagation and coastal impact of tsunami, including implications for decision-making of NTWS. To explore our main question, we construct a finite-fault model of the 2017, Mw 8.1 Tehuantepec earthquake. We employ the rupture model to simulate a transoceanic tsunami modeled by Neowave2D. We generate synthetic time series at

  18. Exceptional Ground Accelerations and Velocities Caused by Earthquakes

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, John

    2008-01-17

    This project aims to understand the characteristics of the free-field strong-motion records that have yielded the 100 largest peak accelerations and the 100 largest peak velocities recorded to date. The peak is defined as the maximum magnitude of the acceleration or velocity vector during the strong shaking. This compilation includes 35 records with peak acceleration greater than gravity, and 41 records with peak velocities greater than 100 cm/s. The results represent an estimated 150,000 instrument-years of strong-motion recordings. The mean horizontal acceleration or velocity, as used for the NGA ground motion models, is typically 0.76 times the magnitude of this vector peak. Accelerations in the top 100 come from earthquakes as small as magnitude 5, while velocities in the top 100 all come from earthquakes with magnitude 6 or larger. Records are dominated by crustal earthquakes with thrust, oblique-thrust, or strike-slip mechanisms. Normal faulting mechanisms in crustal earthquakes constitute under 5% of the records in the databases searched, and an even smaller percentage of the exceptional records. All NEHRP site categories have contributed exceptional records, in proportions similar to the extent that they are represented in the larger database.

  19. High resolution magnetic force microscopy: instrumentation and application for recording media

    NARCIS (Netherlands)

    Porthun, Steffen; Porthun, S.

    This thesis describes aspects of the use of magnetic force microscopy for the study of magnetic recording media. The maximum achievable storage density in magnetic recording is limited by the magnetic reversal behaviour of the medium and by the stability of the written information. The shape and

  20. Responses of a tall building in Los Angeles, California as inferred from local and distant earthquakes

    Science.gov (United States)

    Çelebi, Mehmet; Hasan Ulusoy,; Nori Nakata,

    2016-01-01

    Increasing inventory of tall buildings in the United States and elsewhere may be subjected to motions generated by near and far seismic sources that cause long-period effects. Multiple sets of records that exhibited such effects were retrieved from tall buildings in Tokyo and Osaka ~ 350 km and 770 km from the epicenter of the 2011 Tohoku earthquake. In California, very few tall buildings have been instrumented. An instrumented 52-story building in downtown Los Angeles recorded seven local and distant earthquakes. Spectral and system identification methods exhibit significant low frequencies of interest (~0.17 Hz, 0.56 Hz and 1.05 Hz). These frequencies compare well with those computed by transfer functions; however, small variations are observed between the significant low frequencies for each of the seven earthquakes. The torsional and translational frequencies are very close and are coupled. Beating effect is observed in at least two of the seven earthquake data.

  1. A record of large earthquakes during the past two millennia on the southern Green Valley Fault, California

    Science.gov (United States)

    Lienkaemper, James J.; Baldwin, John N.; Turner, Robert; Sickler, Robert R.; Brown, Johnathan

    2013-01-01

    We document evidence for surface-rupturing earthquakes (events) at two trench sites on the southern Green Valley fault, California (SGVF). The 75-80-km long dextral SGVF creeps ~1-4 mm/yr. We identify stratigraphic horizons disrupted by upward-flowering shears and in-filled fissures unlikely to have formed from creep alone. The Mason Rd site exhibits four events from ~1013 CE to the Present. The Lopes Ranch site (LR, 12 km to the south) exhibits three events from 18 BCE to Present including the most recent event (MRE), 1610 ±52 yr CE (1σ) and a two-event interval (18 BCE-238 CE) isolated by a millennium of low deposition. Using Oxcal to model the timing of the 4-event earthquake sequence from radiocarbon data and the LR MRE yields a mean recurrence interval (RI or μ) of 199 ±82 yr (1σ) and ±35 yr (standard error of the mean), the first based on geologic data. The time since the most recent earthquake (open window since MRE) is 402 yr ±52 yr, well past μ~200 yr. The shape of the probability density function (pdf) of the average RI from Oxcal resembles a Brownian Passage Time (BPT) pdf (i.e., rather than normal) that permits rarer longer ruptures potentially involving the Berryessa and Hunting Creek sections of the northernmost GVF. The model coefficient of variation (cv, σ/μ) is 0.41, but a larger value (cv ~0.6) fits better when using BPT. A BPT pdf with μ of 250 yr and cv of 0.6 yields 30-yr rupture probabilities of 20-25% versus a Poisson probability of 11-17%.

  2. Geomorphic legacy of medieval Himalayan earthquakes in the Pokhara Valley

    Science.gov (United States)

    Schwanghart, Wolfgang; Bernhardt, Anne; Stolle, Amelie; Hoelzmann, Philipp; Adhikari, Basanta R.; Andermann, Christoff; Tofelde, Stefanie; Merchel, Silke; Rugel, Georg; Fort, Monique; Korup, Oliver

    2016-04-01

    The Himalayas and their foreland belong to the world's most earthquake-prone regions. With millions of people at risk from severe ground shaking and associated damages, reliable data on the spatial and temporal occurrence of past major earthquakes is urgently needed to inform seismic risk analysis. Beyond the instrumental record such information has been largely based on historical accounts and trench studies. Written records provide evidence for damages and fatalities, yet are difficult to interpret when derived from the far-field. Trench studies, in turn, offer information on rupture histories, lengths and displacements along faults but involve high chronological uncertainties and fail to record earthquakes that do not rupture the surface. Thus, additional and independent information is required for developing reliable earthquake histories. Here, we present exceptionally well-dated evidence of catastrophic valley infill in the Pokhara Valley, Nepal. Bayesian calibration of radiocarbon dates from peat beds, plant macrofossils, and humic silts in fine-grained tributary sediments yields a robust age distribution that matches the timing of nearby M>8 earthquakes in ~1100, 1255, and 1344 AD. The upstream dip of tributary valley fills and X-ray fluorescence spectrometry of their provenance rule out local sediment sources. Instead, geomorphic and sedimentary evidence is consistent with catastrophic fluvial aggradation and debris flows that had plugged several tributaries with tens of meters of calcareous sediment from the Annapurna Massif >60 km away. The landscape-changing consequences of past large Himalayan earthquakes have so far been elusive. Catastrophic aggradation in the wake of two historically documented medieval earthquakes and one inferred from trench studies underscores that Himalayan valley fills should be considered as potential archives of past earthquakes. Such valley fills are pervasive in the Lesser Himalaya though high erosion rates reduce

  3. Sedimentary records of past earthquakes in Boraboy Lake during the last ca 600 years (North Anatolian Fault, Turkey)

    KAUST Repository

    Avsar, Ulas

    2015-05-21

    Multiproxy sedimentological analyses along 4.9 m-long sequence of Boraboy Lake, which is located on the central eastern part of the North Anatolian Fault (NAF), reveal the sedimentary traces of past large earthquakes in the region. The lake has a relatively large catchment area (10 km2) compared to its size (0.12 km2), which renders sedimentation sensitive to heavy rain/storm events. Accordingly, the background sedimentation, which is composed of faintly laminated reddish/yellowish brown clayey silt, is frequently interrupted by organic-rich intercalations probably due to heavy rain/storm events transporting terrestrial plant remains from the densely vegetated catchment. In addition to frequent organic-rich intercalations, the background sedimentation is interrupted by four mass-wasting deposits (MWD) of which thickness range between 15 and 50 cm. High-resolution ITRAX μXRF data confirms higher homogeneity along the MWDs (E1-E4) compared to the background sedimentation. Based on 137Cs and 210Pbxs dating and radiocarbon chronology, three MWDs detected in Boraboy sequence (E2, E3 and E4) temporally correlate with large historical earthquakes along the NAF; the 1943 Tosya (Ms= 7.6) and/or 1942 Niksar-Erbaa (Ms= 7.1), the 1776 Amasya-Merzifon and the 1668 North Anatolian (Ms= 7.9) earthquakes. The youngest MWD in the sequence (E1), which is dated to early 2000s, does not correlate with any strong earthquake in the region. This MWD was probably a single mass-wasting event due to routine overloading and oversteepening on the delta front formed by the main inlet of the lake. In subaqueous paleoseismology, coevality of multi-location mass-wasting events is used as a criterion to assign a seismic triggering mechanism, and to rule out mass-wasting events due to routine overloading/oversteepening of subaqueous slopes. Within this context, Boraboy sequence provides a valuable example to discuss sedimentological imprints of single- vs. multi-source MWDs.

  4. Soil–structure interaction analyses to locate nuclear power plant free-field seismic instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, James J., E-mail: jasjjoh@aol.com [James J. Johnson and Associates, Alamo, CA (United States); Ake, Jon P. [US Nuclear Regulatory Commission, Washington, DC (United States); Maslenikov, Oleg R. [James J. Johnson and Associates, Alamo, CA (United States); Kenneally, Roger M. [Consultant, Seminole, FL (United States)

    2015-12-15

    Highlights: • Determine the location of seismic instrumentation so that recorded motion will be free-field motion. • Certified Designs of nuclear island for AP1000 and EPR; ABWR Reactor Building were analyzed. • Three site conditions and multiple recorded time histories were considered. • Instrumentation located 1-diameter from the edge of structure/foundation is adequate. • Acceptance criteria were probability of non-exceedance of response spectra values. - Abstract: The recorded earthquake ground motion at the nuclear power plant site is needed for several purposes. US Nuclear Regulatory Commission (NRC) Regulatory Guide 1.12, Nuclear Power Plant Instrumentation for Earthquakes, NRC (1997a), describes acceptable instrumentation to meet the requirements in NRC's regulations pertaining to earthquake engineering criteria for nuclear power plants. The ground motion data recorded by the free-field seismic instrumentation are used to compare the actual earthquake motion at the site with the design input motion. The result of the comparison determines if the Operating Basis Earthquake ground motion (OBE) has been exceeded and plant shutdown is required per the guidance in NRC Regulatory Guide 1.166, Pre-Earthquake Planning and Immediate Nuclear Power Plant Operator Postearthquake Actions, NRC (1979b). The free-field is defined as a location on the ground surface or in the site soil column that is sufficiently distant from the site structures to be essentially unaffected by the vibration of the site structures.

  5. Estimated cause of extreme acceleration records at the KiK-net IWTH25 station during the 2008 Iwate-Miyagi Nairiku earthquake, Japan

    Science.gov (United States)

    Ohmachi, Tatsuo; Inoue, Shusaku; Mizuno, Ken-Ichi; Yamada, Masato

    During the 2008 Iwate-Miyagi Nairiku earthquake in Japan (MJ =7.2), extremely high accelerations were recorded at the KiK-net IWTH25 (Ichinoseki-nishi) station. The peak acceleration in the vertical component of the surface record was about 4 g where g is acceleration due to gravity, and the upward acceleration in the surface record was much larger than the downward acceleration. Some researchers have suggested that the ground surface was tossed into the air like a body on a trampoline. However, additional features found in the surface record suggest rocking motion accompanied with downward impact of the station with the ground. For example, there are many vertical peaks that can be found to occur at the same time as the horizontal peaks. After obtaining information about the station, in-situ investigations, shake-table experiments, and numerical simulations were conducted to determine the fundamental characteristics of the rocking motion and to reproduce the acceleration time histories of the surface record by using the bore-hole record at a depth of 260 m as the input motion. Prior to the numerical simulation, the wave velocities of subsurface layers were evaluated from Fourier spectra of both records, which showed that the velocities were reduced considerably during the main shock. A 2-D FEM code capable of handling separation and impact between the elements was used for the numerical simulation. Simulation results are shown in Figs. 17 and 18 indicating the impact between the IWTH25 station and the ground at around 4 sec when the acceleration in the vertical direction was about 4 g. Three kinds of acceleration time histories are shown with fairly good agreement between the simulated and observed time histories, suggesting the influence of the station is included in the record. It is also indicated that the vertical acceleration at the free surface without the influence of the IWTH25 station is about 1.6 g.

  6. Historic Eastern Canadian earthquakes

    International Nuclear Information System (INIS)

    Asmis, G.J.K.; Atchinson, R.J.

    1981-01-01

    Nuclear power plants licensed in Canada have been designed to resist earthquakes: not all plants, however, have been explicitly designed to the same level of earthquake induced forces. Understanding the nature of strong ground motion near the source of the earthquake is still very tentative. This paper reviews historical and scientific accounts of the three strongest earthquakes - St. Lawrence (1925), Temiskaming (1935), Cornwall (1944) - that have occurred in Canada in 'modern' times, field studies of near-field strong ground motion records and their resultant damage or non-damage to industrial facilities, and numerical modelling of earthquake sources and resultant wave propagation to produce accelerograms consistent with the above historical record and field studies. It is concluded that for future construction of NPP's near-field strong motion must be explicitly considered in design

  7. Earthquakes Sources Parameter Estimation of 20080917 and 20081114 Near Semangko Fault, Sumatra Using Three Components of Local Waveform Recorded by IA Network Station

    Directory of Open Access Journals (Sweden)

    Madlazim

    2012-04-01

    Full Text Available The 17/09/2008 22:04:80 UTC and 14/11/2008 00:27:31.70 earthquakes near Semangko fault were analyzed to identify the fault planes. The two events were relocated to assess physical insight against the hypocenter uncertainty. The datas used to determine source parameters of both earthquakes were three components of local waveform recorded by Geofon broadband IA network stations, (MDSI, LWLI, BLSI and RBSI for the event of 17/09/2008 and (MDSI, LWLI, BLSI and KSI for the event of 14/11/2008. Distance from the epicenter to all station was less than 5°. Moment tensor solution of two events was simultaneously analyzed by determination of the centroid position. Simultaneous analysis covered hypocenter position, centroid position and nodal planes of two events indicated Semangko fault planes. Considering that the Semangko fault zone is a high seismicity area, the identification of the seismic fault is important for the seismic hazard investigation in the region.

  8. Digital Recording and Non-Destructive Techniques for the Understanding of Structural Performance for Rehabilitating Historic Structures at the Kathmandu Valley after Gorkha Earthquake 2015

    Science.gov (United States)

    Shrestha, S.; Reina Ortiz, M.; Gutland, M.; Napolitano, R.; Morris, I. M.; Santana Quintero, M.; Erochko, J.; Kawan, S.; Shrestha, R. G.; Awal, P.; Suwal, S.; Duwal, S.; Maharjan, D. K.

    2017-08-01

    On 25 April 2015, the Gorkha earthquake of magnitude 7.8, severely damaged the cultural heritage sites of Nepal. In particular, the seven monument zones of the Kathmandu Valley World Heritage Site suffered extensive damage. Out of 195 surveyed monuments, 38 have completely collapsed and 157 partially damaged (DoA, 2015). In particular, the world historic city of Bhaktapur was heavily affected by the earthquake. There is, in general, a lack of knowledge regarding the traditional construction technology used in many of the most important temple monuments in Bhaktapur. To address this limitation and to assist in reconstruction and rehabilitation of the area, this study documents the existing condition of different historic structures in the Kathmandu Valley. In particular, the Nyatapola Temple is studied in detail. To record and document the condition of this temple, a combination of laser scanning and terrestrial and aerial photogrammetry are used. By also including evaluation of the temple and its supporting plinth structure using non-destructive evaluation techniques like geo-radar and micro-tremor dynamic analysis, this study will form the basis of a structural analysis study to assess the anticipated future seismic performance of the Nyatapola Temple.

  9. The 1964 Great Alaska Earthquake and tsunamis: a modern perspective and enduring legacies

    Science.gov (United States)

    Brocher, Thomas M.; Filson, John R.; Fuis, Gary S.; Haeussler, Peter J.; Holzer, Thomas L.; Plafker, George; Blair, J. Luke

    2014-01-01

    The magnitude 9.2 Great Alaska Earthquake that struck south-central Alaska at 5:36 p.m. on Friday, March 27, 1964, is the largest recorded earthquake in U.S. history and the second-largest earthquake recorded with modern instruments. The earthquake was felt throughout most of mainland Alaska, as far west as Dutch Harbor in the Aleutian Islands some 480 miles away, and at Seattle, Washington, more than 1,200 miles to the southeast of the fault rupture, where the Space Needle swayed perceptibly. The earthquake caused rivers, lakes, and other waterways to slosh as far away as the coasts of Texas and Louisiana. Water-level recorders in 47 states—the entire Nation except for Connecticut, Delaware, and Rhode Island— registered the earthquake. It was so large that it caused the entire Earth to ring like a bell: vibrations that were among the first of their kind ever recorded by modern instruments. The Great Alaska Earthquake spawned thousands of lesser aftershocks and hundreds of damaging landslides, submarine slumps, and other ground failures. Alaska’s largest city, Anchorage, located west of the fault rupture, sustained heavy property damage. Tsunamis produced by the earthquake resulted in deaths and damage as far away as Oregon and California. Altogether the earthquake and subsequent tsunamis caused 129 fatalities and an estimated $2.3 billion in property losses (in 2013 dollars). Most of the population of Alaska and its major transportation routes, ports, and infrastructure lie near the eastern segment of the Aleutian Trench that ruptured in the 1964 earthquake. Although the Great Alaska Earthquake was tragic because of the loss of life and property, it provided a wealth of data about subductionzone earthquakes and the hazards they pose. The leap in scientific understanding that followed the 1964 earthquake has led to major breakthroughs in earth science research worldwide over the past half century. This fact sheet commemorates Great Alaska Earthquake and

  10. High resolution climate reconstructions of recent warming using instrumental and ice core records from coastal Antarctica

    Digital Repository Service at National Institute of Oceanography (India)

    Thamban, M.; Naik, S.S.; Laluraj, C.M.; Ravindra, R.

    for the past 4 years (Thamban et al., 2006). Chronological control for the IND-25/B5 ice core was based on multiple and complimentary methods: (i) atomic bomb (Tritium) markers; (ii) annual layer counting using stable isotope records; and (iii) volcanic...

  11. Fault structure in the Nepal Himalaya as illuminated by aftershocks of the 2015 Mw 7.8 Gorkha earthquake recorded by the local NAMASTE network

    Science.gov (United States)

    Ghosh, A.; Mendoza, M.; LI, B.; Karplus, M. S.; Nabelek, J.; Sapkota, S. N.; Adhikari, L. B.; Klemperer, S. L.; Velasco, A. A.

    2017-12-01

    Geometry of the Main Himalayan Thrust (MHT), that accommodates majority of the plate motion between Indian and Eurasian plate, is being debated for a long time. Different models have been proposed; some of them are significantly different from others. Obtaining a well constrained geometry of the MHT is challenging mainly because of the lack of high quality data, inherent low resolution and non-uniqueness of the models. We used a dense local seismic network - NAMASTE - to record and analyze a prolific aftershock sequence following the 2015 Mw 7.8 Gorkha earthquake, and determine geometry of the MHT constrained by precisely located well-constrained aftershocks. We detected and located more than 15,000 aftershocks of the Gorkha earthquake using Hypoinverse and then relatively relocated using HypoDD algorithm. We selected about 7,000 earthquakes that are particularly well constrained to analyze the geometry of the megathrust. They illuminate fault structure in this part of the Himalaya with unprecedented detail. The MHT shows two subhorizontal planes connected by a duplex structure. The duplex structure is characterized by multiple steeply dipping planes. In addition, we used four large-aperture continental-scale seismic arrays at teleseismic distances to backproject high-frequency seismic radiation. Moreover, we combined all arrays to significantly increase the resolution and detectability. We imaged rupture propagation of the mainshock showing complexity near the end of the rupture that might help arresting of the rupture to the east. Furthermore, we continuously scanned teleseismic data for two weeks starting from immediately after the mainshock to detect and locate aftershock activity only using the arrays. Spatial pattern of the aftershocks was similar to the existing global catalog using conventional seismic network and technique. However, we detected more than twice as many aftershocks using the array technique compared to the global catalog including many

  12. The Non-Regularity of Earthquake Recurrence in California: Lessons From Long Paleoseismic Records in Simple vs Complex Fault Regions (Invited)

    Science.gov (United States)

    Rockwell, T. K.

    2010-12-01

    A long paleoseismic record at Hog Lake on the central San Jacinto fault (SJF) in southern California documents evidence for 18 surface ruptures in the past 3.8-4 ka. This yields a long-term recurrence interval of about 210 years, consistent with its slip rate of ~16 mm/yr and field observations of 3-4 m of displacement per event. However, during the past 3800 years, the fault has switched from a quasi-periodic mode of earthquake production, during which the recurrence interval is similar to the long-term average, to clustered behavior with the inter-event periods as short as a few decades. There are also some periods as long as 450 years during which there were no surface ruptures, and these periods are commonly followed by one to several closely-timed ruptures. The coefficient of variation (CV) for the timing of these earthquakes is about 0.6 for the past 4000 years (17 intervals). Similar behavior has been observed on the San Andreas Fault (SAF) south of the Transverse Ranges where clusters of earthquakes have been followed by periods of lower seismic production, and the CV is as high as 0.7 for some portions of the fault. In contrast, the central North Anatolian Fault (NAF) in Turkey, which ruptured in 1944, appears to have produced ruptures with similar displacement at fairly regular intervals for the past 1600 years. With a CV of 0.16 for timing, and close to 0.1 for displacement, the 1944 rupture segment near Gerede appears to have been both periodic and characteristic. The SJF and SAF are part of a broad plate boundary system with multiple parallel strands with significant slip rates. Additional faults lay to the east (Eastern California shear zone) and west (faults of the LA basin and southern California Borderland), which makes the southern SAF system a complex and broad plate boundary zone. In comparison, the 1944 rupture section of the NAF is simple, straight and highly localized, which contrasts with the complex system of parallel faults in southern

  13. Adaptively smoothed seismicity earthquake forecasts for Italy

    Directory of Open Access Journals (Sweden)

    Yan Y. Kagan

    2010-11-01

    Full Text Available We present a model for estimation of the probabilities of future earthquakes of magnitudes m ≥ 4.95 in Italy. This model is a modified version of that proposed for California, USA, by Helmstetter et al. [2007] and Werner et al. [2010a], and it approximates seismicity using a spatially heterogeneous, temporally homogeneous Poisson point process. The temporal, spatial and magnitude dimensions are entirely decoupled. Magnitudes are independently and identically distributed according to a tapered Gutenberg-Richter magnitude distribution. We have estimated the spatial distribution of future seismicity by smoothing the locations of past earthquakes listed in two Italian catalogs: a short instrumental catalog, and a longer instrumental and historic catalog. The bandwidth of the adaptive spatial kernel is estimated by optimizing the predictive power of the kernel estimate of the spatial earthquake density in retrospective forecasts. When available and reliable, we used small earthquakes of m ≥ 2.95 to reveal active fault structures and 29 probable future epicenters. By calibrating the model with these two catalogs of different durations to create two forecasts, we intend to quantify the loss (or gain of predictability incurred when only a short, but recent, data record is available. Both forecasts were scaled to five and ten years, and have been submitted to the Italian prospective forecasting experiment of the global Collaboratory for the Study of Earthquake Predictability (CSEP. An earlier forecast from the model was submitted by Helmstetter et al. [2007] to the Regional Earthquake Likelihood Model (RELM experiment in California, and with more than half of the five-year experimental period over, the forecast has performed better than the others.

  14. The Relationship Between Radiative Forcing and Temperature. What Do Statistical Analyses of the Instrumental Temperature Record Measure?

    International Nuclear Information System (INIS)

    Kaufmann, R.K.; Kauppi, H.; Stock, J.H.

    2006-01-01

    Comparing statistical estimates for the long-run temperature effect of doubled CO2 with those generated by climate models begs the question, is the long-run temperature effect of doubled CO2 that is estimated from the instrumental temperature record using statistical techniques consistent with the transient climate response, the equilibrium climate sensitivity, or the effective climate sensitivity. Here, we attempt to answer the question, what do statistical analyses of the observational record measure, by using these same statistical techniques to estimate the temperature effect of a doubling in the atmospheric concentration of carbon dioxide from seventeen simulations run for the Coupled Model Intercomparison Project 2 (CMIP2). The results indicate that the temperature effect estimated by the statistical methodology is consistent with the transient climate response and that this consistency is relatively unaffected by sample size or the increase in radiative forcing in the sample

  15. Source Rupture Process of the 2016 Kumamoto Prefecture, Japan, Earthquake Derived from Near-Source Strong-Motion Records

    Science.gov (United States)

    Zheng, A.; Zhang, W.

    2016-12-01

    On 15 April, 2016 the great earthquake with magnitude Mw7.1 occurred in Kumamoto prefecture, Japan. The focal mechanism solution released by F-net located the hypocenter at 130.7630°E, 32.7545°N, at a depth of 12.45 km, and the strike, dip, and the rake angle of the fault were N226°E, 84° and -142° respectively. The epicenter distribution and focal mechanisms of aftershocks implied the mechanism of the mainshock might have changed in the source rupture process, thus a single focal mechanism was not enough to explain the observed data adequately. In this study, based on the inversion result of GNSS and InSAR surface deformation with active structures for reference, we construct a finite fault model with focal mechanism changes, and derive the source rupture process by multi-time-window linear waveform inversion method using the strong-motion data (0.05 1.0Hz) obtained by K-NET and KiK-net of Japan. Our result shows that the Kumamoto earthquake is a right-lateral strike slipping rupture event along the Futagawa-Hinagu fault zone, and the seismogenic fault is divided into a northern segment and a southern one. The strike and the dip of the northern segment are N235°E, 60° respectively. And for the southern one, they are N205°E, 72° respectively. The depth range of the fault model is consistent with the depth distribution of aftershocks, and the slip on the fault plane mainly concentrate on the northern segment, in which the maximum slip is about 7.9 meter. The rupture process of the whole fault continues for approximately 18-sec, and the total seismic moment released is 5.47×1019N·m (Mw 7.1). In addition, the essential feature of the distribution of PGV and PGA synthesized by the inversion result is similar to that of observed PGA and seismic intensity.

  16. The Terminator Time in subionospheric VLF/LF diurnal variation as recorded by the Romanian VLF/LF radio monitoring system related to earthquake occurrence and volcano erruptions

    Science.gov (United States)

    Moldovan, I. A.; Moldovan, A. S.; Biagi, P. F.; Ionescu, C.; Schwingenschuh, K.; Boudjada, M. Y.

    2012-04-01

    The Romanian VLF/LF monitoring system consisting in a radio receiver and the infrastructure that is necessary to record and transmit the collected data is part of the European international network named INFREP. Information on electromagnetic fields' intensities created by transmitters at a receiving site are indicating the quality of the propagation along the paths between the receivers and transmitters. Studying the ionosphere's influences on the electromagnetic waves' propagation along a certain path is a method to put into evidence possible modifications of its lower structure and composition as earthquakes' precursors. The VLF/LF receiver installed in Romania was put into operation in February 2009 and has already 3 years of testing, functioning and proving its utility in the forecast of some earthquakes or volcanic eruptions. Simultaneously we monitor, in the same site with the VLF/LF receiver, the vertical atmospheric electric field and different other meteorological parameters as: temperature, pressure or rainfall. The global magnetic conditions are emphasized with the help of Daily Geomagnetic Index Kp. At a basic level, the adopted analysis consists in a simple statistical evaluation of the signals by comparing the instantaneous values to the trend of the signal. In this paper we pay attention to the terminator times in subionospheric VLF/LF diurnal variation, which are defined as the times of minimum in amplitude (or phase) around sunrise and sunset. These terminator times are found to shift significantly just around the earthquake. In the case of Kobe earthquake, there were found significant shifts in both morning and evening terminator times and these authors interpreted the shift in terminator time in terms of the lowering of lower ionosphere by using the full-wave mode theory. A LabVIEW application which accesses the VLF/LF receiver through internet was developed. This program opens the receiver's web-page and automatically retrieves the list of data

  17. Seabed Motion During Sediment Density Flows as Recorded by Displaced Man-Made Motion-Recording Boulders and a Heavy Instrument Platform

    Science.gov (United States)

    Gwiazda, R.; Paull, C. K.; Kieft, B.; Bird, L.; Klimov, D.; Herlien, R.; Sherman, A.; McCann, M. P.; Sumner, E.; Talling, P.; Xu, J.; Parsons, D. R.; Maier, K. L.; Barry, J.

    2017-12-01

    Over a period of 18 months the Coordinated Canyon Experiment documented the passage of at least 15 sediment density flows in Monterey Canyon, offshore California, with an array of moorings and sensors placed from 200 m to 1,850 m water depths. Free-standing `smart' boulders (Benthic Event Detectors, BED) and a 1,000 Kg tripod with an Acoustic Monitoring Transponder (AMT) and a BED attached to it were deployed in the upper canyon to detect seabed motions during sediment density flows. BEDs consist of spheres made of a combination of metal, plastic and syntactic foam ballasted to 2.1 g/cm3 density, containing accelerometers along three orthogonal axes, a time recorder, and a pressure sensor inside a pressure case rated to 500 m water depth. Acceleration of ≥ 0.008 G triggers data collection at a recording rate of 50 Hz until motion stops. Built-in acoustic beacons and modems allow for BEDs to be relocated, and data to be downloaded, even when BEDs are buried in sediment to depths of >1 m. Over the course of the study, depth changes and velocities of 24 BED movements during 9 events were recorded. BEDs moved at the velocity of the propagation of the flows down canyon, as documented by the time of arrival of the flow at successive sensors, but sometimes travelled at lower speeds. Seven movements of the AMT tripod were also recorded. In the largest of these, the heavy AMT tripod was transported over a distance of 4.1 Km. For at least four of these seven motions the AMT temperature record indicates that the movements were initiated while the tripod was buried. In one particular event simultaneous movements of five BEDs over a 100 m depth range indicate that the entire seabed was in motion at the same time over a canyon distance of 3.5 Km. Reconstructions of instrument motions in this event from their internally recorded acceleration data show that the AMT displacement was at the front of the event and had no rotational component. In contrast, free standing BEDs at the

  18. In situ energetic particle observations at comet Halley recorded by instrumentation aboard the Giotto and Vega 1 missions

    Energy Technology Data Exchange (ETDEWEB)

    McKenna-Lawlor, S.; Daly, P.; Kirsch, E.; Wilken, B.; O' Sullivan, D.; Thompson, A.; Kecskemety, K.; Somogyi, A.; Coates, A.

    1989-04-01

    Three important observations recorded in the energetic particle data secured at Halley's comet during March 1986 are reviewed. These include (a) quasi periodic variations of cometary ion fluxes observed inbound and outbound by both the EPONA instrument aboard Giotto and by the Tunde-M instrument aboard Vega 1. A possible explanation of the results in terms of a spin modulation of the outgassing rate of the nucleus is discussed; (b) by combining the EPONA data with JPA-IIS data it is possible to infer that the ion fluxes measured at encounter by EPONA were of the water group. These particles displayed energies in excess of those attained by the pick-up process acting alone. Comparisons between energy spectra prepared using the composite observational data and, corresponding, theoretically derived plots suggest that, downstream of the shock (inbound), stochastic (second-order-Fermi) acceleration may have contributed to energizing the particles; (c) large fluxes of electrons (E>300keV) and ions (E>3.5 MeV) were unexpectedly recorded by EPONA in the magnetic cavity. The observed enhancements (up to approximately three orders of magnitude) appear to be cometary in origin.

  19. In situ energetic particle observations at comet Halley recorded by instrumentation aboard the Giotto and Vega 1 missions

    International Nuclear Information System (INIS)

    McKenna-Lawlor, S.; Daly, P.; Kirsch, E.; Wilken, B.; O'Sullivan, D.; Thompson, A.; Kecskemety, K.; Somogyi, A.

    1989-01-01

    Three important observations recorded in the energetic particle data secured at Halley's comet during March 1986 are reviewed. These include (a) quasi periodic variations of cometary ion fluxes observed inbound and outbound by both the EPONA instrument aboard Giotto and by the Tunde-M instrument aboard Vega 1. A possible explanation of the results in terms of a spin modulation of the outgassing rate of the nucleus is discussed; (b) by combining the EPONA data with JPA-IIS data it is possible to infer that the ion fluxes measured at encounter by EPONA were of the water group. These particles displayed energies in excess of those attained by the pick-up process acting alone. Comparisons between energy spectra prepared using the composite observational data and, corresponding, theoretically derived plots suggest that, downstream of the shock (inbound), stochastic (second-order-Fermi) acceleration may have contributed to energizing the particles; (c) large fluxes of electrons (E>300keV) and ions (E>3.5 MeV) were unexpectedly recorded by EPONA in the magnetic cavity. The observed enhancements (up to approximately three orders of magnitude) appear to be cometary in origin

  20. Long-Term Fault Memory: A New Time-Dependent Recurrence Model for Large Earthquake Clusters on Plate Boundaries

    Science.gov (United States)

    Salditch, L.; Brooks, E. M.; Stein, S.; Spencer, B. D.; Campbell, M. R.

    2017-12-01

    A challenge for earthquake hazard assessment is that geologic records often show large earthquakes occurring in temporal clusters separated by periods of quiescence. For example, in Cascadia, a paleoseismic record going back 10,000 years shows four to five clusters separated by approximately 1,000 year gaps. If we are still in the cluster that began 1700 years ago, a large earthquake is likely to happen soon. If the cluster has ended, a great earthquake is less likely. For a Gaussian distribution of recurrence times, the probability of an earthquake in the next 50 years is six times larger if we are still in the most recent cluster. Earthquake hazard assessments typically employ one of two recurrence models, neither of which directly incorporate clustering. In one, earthquake probability is time-independent and modeled as Poissonian, so an earthquake is equally likely at any time. The fault has no "memory" because when a prior earthquake occurred has no bearing on when the next will occur. The other common model is a time-dependent earthquake cycle in which the probability of an earthquake increases with time until one happens, after which the probability resets to zero. Because the probability is reset after each earthquake, the fault "remembers" only the last earthquake. This approach can be used with any assumed probability density function for recurrence times. We propose an alternative, Long-Term Fault Memory (LTFM), a modified earthquake cycle model where the probability of an earthquake increases with time until one happens, after which it decreases, but not necessarily to zero. Hence the probability of the next earthquake depends on the fault's history over multiple cycles, giving "long-term memory". Physically, this reflects an earthquake releasing only part of the elastic strain stored on the fault. We use the LTFM to simulate earthquake clustering along the San Andreas Fault and Cascadia. In some portions of the simulated earthquake history, events would

  1. Analyses of computer programs for the probabilistic estimation of design earthquake and seismological characteristics of the Korean Peninsula

    International Nuclear Information System (INIS)

    Lee, Gi Hwa

    1997-11-01

    The purpose of the present study is to develop predictive equations from simulated motions which are adequate for the Korean Peninsula and analyze and utilize the computer programs for the probabilistic estimation of design earthquakes. In part I of the report, computer programs for the probabilistic estimation of design earthquake are analyzed and applied to the seismic hazard characterizations in the Korean Peninsula. In part II of the report, available instrumental earthquake records are analyzed to estimate earthquake source characteristics and medium properties, which are incorporated into simulation process. And earthquake records are simulated by using the estimated parameters. Finally, predictive equations constructed from the simulation are given in terms of magnitude and hypocentral distances

  2. Using Pitch, Amplitude Modulation, and Spatial Cues for Separation of Harmonic Instruments from Stereo Music Recordings

    Directory of Open Access Journals (Sweden)

    Bryan Pardo

    2007-01-01

    Full Text Available Recent work in blind source separation applied to anechoic mixtures of speech allows for improved reconstruction of sources that rarely overlap in a time-frequency representation. While the assumption that speech mixtures do not overlap significantly in time-frequency is reasonable, music mixtures rarely meet this constraint, requiring new approaches. We introduce a method that uses spatial cues from anechoic, stereo music recordings and assumptions regarding the structure of musical source signals to effectively separate mixtures of tonal music. We discuss existing techniques to create partial source signal estimates from regions of the mixture where source signals do not overlap significantly. We use these partial signals within a new demixing framework, in which we estimate harmonic masks for each source, allowing the determination of the number of active sources in important time-frequency frames of the mixture. We then propose a method for distributing energy from time-frequency frames of the mixture to multiple source signals. This allows dealing with mixtures that contain time-frequency frames in which multiple harmonic sources are active without requiring knowledge of source characteristics.

  3. Instrumental record of debris flow initiation during natural rainfall: Implications for modeling slope stability

    Science.gov (United States)

    Montgomery, D.R.; Schmidt, K.M.; Dietrich, W.E.; McKean, J.

    2009-01-01

    The middle of a hillslope hollow in the Oregon Coast Range failed and mobilized as a debris flow during heavy rainfall in November 1996. Automated pressure transducers recorded high spatial variability of pore water pressure within the area that mobilized as a debris flow, which initiated where local upward flow from bedrock developed into overlying colluvium. Postfailure observations of the bedrock surface exposed in the debris flow scar reveal a strong spatial correspondence between elevated piezometric response and water discharging from bedrock fractures. Measurements of apparent root cohesion on the basal (Cb) and lateral (Cl) scarp demonstrate substantial local variability, with areally weighted values of Cb = 0.1 and Cl = 4.6 kPa. Using measured soil properties and basal root strength, the widely used infinite slope model, employed assuming slope parallel groundwater flow, provides a poor prediction of hydrologie conditions at failure. In contrast, a model including lateral root strength (but neglecting lateral frictional strength) gave a predicted critical value of relative soil saturation that fell within the range defined by the arithmetic and geometric mean values at the time of failure. The 3-D slope stability model CLARA-W, used with locally observed pore water pressure, predicted small areas with lower factors of safety within the overall slide mass at sites consistent with field observations of where the failure initiated. This highly variable and localized nature of small areas of high pore pressure that can trigger slope failure means, however, that substantial uncertainty appears inevitable for estimating hydrologie conditions within incipient debris flows under natural conditions. Copyright 2009 by the American Geophysical Union.

  4. Teleconnection among Asian Summer Monsoon, ENSO and PDO revealed by instrumental and historic records as well as an annual resolution stalagmite record from Lianhua Cave, northwestern Hunan, China

    Science.gov (United States)

    Li, H.; Yin, J.; Yuan, D.; Li, T.

    2013-12-01

    A 33-cm long aragonite stalagmite, LHN-1, from Lianhua Cave (29°09'N, 109°33'E , 459m a.s.l.) in NW Hunan Province of China has been dated by ICP-MS 230Th/U method. The 14 230Th/U dates with less than ×37 years uncertainties yield excellent chronology, showing that the stalagmite grew continuously over the past 3400 years. The 0.1-mm sampling interval for stable isotope analyses provides annual resolution δ18O and δ13C records of the LHN-1 stalagmite. Up-to-dated, a total of 887 measurements for δ18O and δ13C have been made, which reveal detailed monsoonal climatic changes during the past 1000 years. The average values of δ18O and δ13C are -5.83 (‰, PDB) and -3.29 (‰, PDB), respectively. For the youngest part of the δ18O record, we have compared with the instrumentally meteorological records and historical dryness/wetness indexes from the studying area, indicating that stalagmite δ18O on annual-to-decadal scales reflects mainly rainfall change in the monsoonal area, with lighter δ18O reflecting wetter condition. The comparison of the δ18O with the East Asian Summer Monsoon (EASM) index since AD 1850 adopted by IPCC (2007) illustrates that lighter stalagmite δ18O corresponds to stronger EASM. Taking the average δ18O value of the 1000-yr record as an average climatic condition, we have found that the δ18O values during AD 1050~1100, 1125~1225, 1300~1350, 1430~1630 and 1900~1960 are lighter than the average, reflecting stronger EASM and wetter condition. The δ18O values during AD 1100~1125, 1225~1300, 1350~1430, 1630~1900 and 1960 to the present are heavier than the average, indicating weak EASM and drier condition. On decadal-to-centennial scales, the δ13C variations generally follow that of δ18O which probably demonstrates that vegetation above the cave controls the δ13C variations. Further comparisons of the δ18O, EASM, ENSO and PDO show that a negative SOI (El Nino phase) correlates warm PDO phase and higher N. Pacific pressure, resulting

  5. Electromagnetic Manifestation of Earthquakes

    OpenAIRE

    Uvarov Vladimir

    2017-01-01

    In a joint analysis of the results of recording the electrical component of the natural electromagnetic field of the Earth and the catalog of earthquakes in Kamchatka in 2013, unipolar pulses of constant amplitude associated with earthquakes were identified, whose activity is closely correlated with the energy of the electromagnetic field. For the explanation, a hypothesis about the cooperative character of these impulses is proposed.

  6. Electromagnetic Manifestation of Earthquakes

    Directory of Open Access Journals (Sweden)

    Uvarov Vladimir

    2017-01-01

    Full Text Available In a joint analysis of the results of recording the electrical component of the natural electromagnetic field of the Earth and the catalog of earthquakes in Kamchatka in 2013, unipolar pulses of constant amplitude associated with earthquakes were identified, whose activity is closely correlated with the energy of the electromagnetic field. For the explanation, a hypothesis about the cooperative character of these impulses is proposed.

  7. Earthquake prediction

    International Nuclear Information System (INIS)

    Ward, P.L.

    1978-01-01

    The state of the art of earthquake prediction is summarized, the possible responses to such prediction are examined, and some needs in the present prediction program and in research related to use of this new technology are reviewed. Three basic aspects of earthquake prediction are discussed: location of the areas where large earthquakes are most likely to occur, observation within these areas of measurable changes (earthquake precursors) and determination of the area and time over which the earthquake will occur, and development of models of the earthquake source in order to interpret the precursors reliably. 6 figures

  8. Effects of the India–Pakistan border earthquake on the atmospherics at 6 kHz and 9 kHz recorded at Tripura

    Directory of Open Access Journals (Sweden)

    Sudarsan Barui

    2011-04-01

    Full Text Available The unusual variations observed in the records of the integrated field intensity of the atmospherics (IFIA at 6 kHz and 9 kHz at Agartala, Tripura, in the north-eastern state of India (latitude, 23˚ N; longitude, 91.4˚ E during the large earthquake on October 8, 2005 at Muzaffarabad (latitude, 34.53˚ N; longitude, 73.58˚ E in Kashmir in Pakistan are here analyzed. Spiky variations in the IFIA at 6 kHz and 9 kHz were observed several days previous to the day of the earthquake (from midnight, September 28, 2005. The effects persisted for some days, decayed gradually, and eventually ceased on October 31, 2005. The spikes are distinctly superimposed on the ambient level

  9. Instrument specifications and geophysical records for airborne electromagnetic survey of parts of Iron, Baraga, and Dickson Counties, Michigan

    Science.gov (United States)

    Heran, William D.; Smith, Bruce D.

    1980-01-01

    The data presented herein is from an airborne electromagnetic INPUT* survey conducted by Geoterrex Limited of Canada for the U.S. Geological Survey. The survey area is located in the central part of the Upper Peninsula of Michigan, within parts of Iron, Baraga, and Dickinson Counties. The general area covered is between 46°00' and 46°30' latitude and 88°00' and 88°30' longitude (fig. 1).The INPUT survey was flown as part of a U.S. Geological Survey CUSMAP (Conterminous United States Mineral Appraisal Program) project focusing on the Iron River 2° quadrangle. The survey was flown in order to provide geophysical information which will aid in an integrated geological assessment of mineral potentials of this part of the Iron River 2° quadrangle. The flight line spacing was chosen to maximize the areal coverage without a loss of resolution of major lithologic and structural features.East-west flight lines were flown 400 feet above ground at 1/2 mile intervals. Aerial photos were used for navigation, and the flight path was recorded on continuous-strip film. A continuously recording total field ground magnetic station was used to monitor variations in the Earth's magnetic field. One north-south line was flown to provide a tie for the magnetic data, which was recorded simultaneously with the electromagnetic data by a sensor mounted in the tail of the aircraft. This report is one of two open-file reports. The map in the other report Heran and Smith (1980) shows locations of the fiducial points, the flight lines, preliminary locations of anomalies and conductive zones; all plotted on an air photomosaic. The latitude and longitude ticks marked on this map are only approximate due to distortion in air photos used to recover the flight line position. This map is preliminary and is not to be considered a final interpretation. The present report contains a description of the instrument specifications, a copy of the ground station magnetic data, and a record of the

  10. Strong T-phases recorded in the Aleutian Arc following the April 20, 2006 Koryakia, Russia Mw=7.6 earthquake

    Science.gov (United States)

    Jacobs, K. M.; McNutt, S. R.; Reyes, C. G.; Deangelis, S.

    2006-12-01

    The April 20, 2006 Mw=7.6 earthquake that occurred in Koryakia, Russia, just North of Kamchatka, produced very clear T-phases on seismic stations in the Aleutian Islands of Alaska. The seismic stations are maintained by the Alaska Volcano Observatory (AVO) to monitor volcanoes. Strong T-phases were recorded by most of the AVO network. The well-distributed locations of the AVO stations along most of the arc, allow unusually clear observations of phase travel times and path effects. T-phases were recorded most clearly and with highest amplitudes in the central and western Aleutians. A sharp decline in amplitude is seen moving east across the arc as the path crosses the Alaskan continental shelf in the eastern Bering Sea. The partial destructive effects of the Bower's Ridge blocking part of the energy are evident at stations on several of the westernmost Aleutian volcanoes. In the central Aleutians several volcano networks recorded a strong secondary T-phase which we believe to be a reflection from the continental shelf edge or from somewhere else along the path. There are other possible interpretations to this signal, which are also being investigated. Using arrival times and distances of the T-phases we have calculated an average apparent velocity in the SOFAR channel of about 1550 m/s. This is slightly above the predicted speeds of 1400-1500 m/s for the Bering Sea. Investigations of the causes of the velocities variations as well as the secondary T-phases are ongoing and will likely yield new information about seismic and acoustic propagation in the Bering Sea.

  11. Joint Inversion of 1-Hz GPS Data and Strong Motion Records for the Rupture Process of the 2008 Iwate-Miyagi Nairiku Earthquake: Objectively Determining Relative Weighting

    Science.gov (United States)

    Wang, Z.; Kato, T.; Wang, Y.

    2015-12-01

    The spatiotemporal fault slip history of the 2008 Iwate-Miyagi Nairiku earthquake, Japan, is obtained by the joint inversion of 1-Hz GPS waveforms and near-field strong motion records. 1-Hz GPS data from GEONET is processed by GAMIT/GLOBK and then a low-pass filter of 0.05 Hz is applied. The ground surface strong motion records from stations of K-NET and Kik-Net are band-pass filtered for the range of 0.05 ~ 0.3 Hz and integrated once to obtain velocity. The joint inversion exploits a broader frequency band for near-field ground motions, which provides excellent constraints for both the detailed slip history and slip distribution. A fully Bayesian inversion method is performed to simultaneously and objectively determine the rupture model, the unknown relative weighting of multiple data sets and the unknown smoothing hyperparameters. The preferred rupture model is stable for different choices of velocity structure model and station distribution, with maximum slip of ~ 8.0 m and seismic moment of 2.9 × 1019 Nm (Mw 6.9). By comparison with the single inversion of strong motion records, the cumulative slip distribution of joint inversion shows sparser slip distribution with two slip asperities. One common slip asperity extends from the hypocenter southeastward to the ground surface of breakage; another slip asperity, which is unique for joint inversion contributed by 1-Hz GPS waveforms, appears in the deep part of fault where very few aftershocks are occurring. The differential moment rate function of joint and single inversions obviously indicates that rich high frequency waves are radiated in the first three seconds but few low frequency waves.

  12. Design of a Freestanding Noise Measurement and Recording System to Predict the Intensity and Location of Electromagnetic Radiation from Earthquakes.

    Science.gov (United States)

    1984-12-01

    the application of an EMP will result in movement of the diffuse layered ions and liquid [Ref. 10]. kpplied EM? and viscous force is given by: 1e...0.1 gamma 1- conductivity, /v= 4 x 10- 7, v = velocity,=length scae B. TELLURIC CURRENTS AB i~, 4 = c"E / D 0O. 0 1 gamma conductivity, E...interface amplifier was designed to set full scale minimum and maximum needle movement in the chart recorder. Calibration of the meter movement was

  13. CERES Top-of-Atmosphere Earth Radiation Budget Climate Data Record: Accounting for in-Orbit Changes in Instrument Calibration

    Directory of Open Access Journals (Sweden)

    Norman G. Loeb

    2016-02-01

    Full Text Available The Clouds and the Earth’s Radiant Energy System (CERES project provides observations of Earth’s radiation budget using measurements from CERES instruments onboard the Terra, Aqua and Suomi National Polar-orbiting Partnership (S-NPP satellites. As the objective is to create a long-term climate data record, it is necessary to periodically reprocess the data in order to incorporate the latest calibration changes and algorithm improvements. Here, we focus on the improvements and validation of CERES Terra and Aqua radiances in Edition 4, which are used to generate higher-level climate data products. Onboard sources indicate that the total (TOT channel response to longwave (LW radiation has increased relative to the start of the missions by 0.4% to 1%. In the shortwave (SW, the sensor response change ranges from −0.4% to 0.6%. To account for in-orbit changes in SW spectral response function (SRF, direct nadir radiance comparisons between instrument pairs on the same satellite are made and an improved wavelength dependent degradation model is used to adjust the SRF of the instrument operating in a rotating azimuth plane scan mode. After applying SRF corrections independently to CERES Terra and Aqua, monthly variations amongst these instruments are highly correlated and the standard deviation in the difference of monthly anomalies is 0.2 Wm−2 for ocean and 0.3 Wm−2 for land/desert. Additionally, trends in CERES Terra and Aqua monthly anomalies are consistent to 0.21 Wm−2 per decade for ocean and 0.31 Wm−2 per decade for land/desert. In the LW, adjustments to the TOT channel SRF are made to ensure that removal of the contribution from the SW portion of the TOT channel with SW channel radiance measurements during daytime is consistent throughout the mission. Accordingly, anomalies in day–night LW difference in Edition 4 are more consistent compared to Edition 3, particularly for the Aqua land/desert case.

  14. Estimation of Source Parameters of Historical Major Earthquakes from 1900 to 1970 around Asia and Analysis of Their Uncertainties

    Science.gov (United States)

    Han, J.; Zhou, S.

    2017-12-01

    Asia, located in the conjoined areas of Eurasian, Pacific, and Indo-Australian plates, is the continent with highest seismicity. Earthquake catalogue on the bases of modern seismic network recordings has been established since around 1970 in Asia and the earthquake catalogue before 1970 was much more inaccurate because of few stations. With a history of less than 50 years of modern earthquake catalogue, researches in seismology are quite limited. After the appearance of improved Earth velocity structure model, modified locating method and high-accuracy Optical Character Recognition technique, travel time data of earthquakes from 1900 to 1970 can be included in research and more accurate locations can be determined for historical earthquakes. Hence, parameters of these historical earthquakes can be obtained more precisely and some research method such as ETAS model can be used in a much longer time scale. This work focuses on the following three aspects: (1) Relocating more than 300 historical major earthquakes (M≥7.0) in Asia based on the Shide Circulars, International Seismological Summary and EHB Bulletin instrumental records between 1900 and 1970. (2) Calculating the focal mechanisms of more than 50 events by first motion records of P wave of ISS. (3) Based on the geological data, tectonic stress field and the result of relocation, inferring focal mechanisms of historical major earthquakes.

  15. Development of the Quality of Australian Nursing Documentation in Aged Care (QANDAC) instrument to assess paper-based and electronic resident records.

    Science.gov (United States)

    Wang, Ning; Björvell, Catrin; Hailey, David; Yu, Ping

    2014-12-01

    To develop an Australian nursing documentation in aged care (Quality of Australian Nursing Documentation in Aged Care (QANDAC)) instrument to measure the quality of paper-based and electronic resident records. The instrument was based on the nursing process model and on three attributes of documentation quality identified in a systematic review. The development process involved five phases following approaches to designing criterion-referenced measures. The face and content validities and the inter-rater reliability of the instrument were estimated using a focus group approach and consensus model. The instrument contains 34 questions in three sections: completion of nursing history and assessment, description of care process and meeting the requirements of data entry. Estimates of the validity and inter-rater reliability of the instrument gave satisfactory results. The QANDAC instrument may be a useful audit tool for quality improvement and research in aged care documentation. © 2013 ACOTA.

  16. Earthquake-induced soft-sediment deformations and seismically amplified erosion rates recorded in varved sediments of Köyceğiz Lake (SW Turkey)

    KAUST Repository

    Avsar, Ulas; Jonsson, Sigurjon; Avşar, Ö zgü r; Schmidt, Sabine

    2016-01-01

    sequence of Köyceğiz Lake (SW Turkey) that we compare with estimated peak ground acceleration (PGA) values of several nearby earthquakes. We find that earthquakes exceeding estimated PGA values of ca. 20 cm/s2 can induce soft-sediment deformations (SSD

  17. GEOS seismograms recorded for aftershocks of the earthquakes of December 7, 1988, near Spitak, Armenia SSR, during the time period 3 January 1989 through 2 February 1988 (UTC)

    Science.gov (United States)

    Borcherdt, R.D.; Glassmoyer, Gary; Cranswick, Edward

    1989-01-01

    The earthquakes of December 7, 1988, near Spitak, Armenia SSR, serve as another grim reminder of the serious hazard that earthquakes pose throughout the world. We extend our heartfelt sympathies to the families of the earthquake victims and intend that our cooperative scientific endeavours will help reduce losses in future earthquakes. Only through a better understanding of earthquake hazards can earthquake losses be reduced for all peoples in seismically active regions of the world.The tragic consequences of these earthquakes remind scientists and public officials alike of their urgent responsibilities to understand and mitigate the effects of earthquakes. On behalf of the U.S. Geological Survey, I would like to express appreciation to our Soviet colleagues for their kind invitation to participate in joint scientific and engineering studies. Without their cooperation and generous assistance, the conduct of these studies would not have been possible.This report provides seismologic and geologic data collected during the time period December 21, 1988, through February 2, 1989. These data are presented in their entirety to expedite analysis of the data set for inferences regarding hazard mitigation actions, applicable not only in Armenia but other regions of the world exposed to high seismic risk

  18. Historical earthquake research in Austria

    Science.gov (United States)

    Hammerl, Christa

    2017-12-01

    Austria has a moderate seismicity, and on average the population feels 40 earthquakes per year or approximately three earthquakes per month. A severe earthquake with light building damage is expected roughly every 2 to 3 years in Austria. Severe damage to buildings ( I 0 > 8° EMS) occurs significantly less frequently, the average period of recurrence is about 75 years. For this reason the historical earthquake research has been of special importance in Austria. The interest in historical earthquakes in the past in the Austro-Hungarian Empire is outlined, beginning with an initiative of the Austrian Academy of Sciences and the development of historical earthquake research as an independent research field after the 1978 "Zwentendorf plebiscite" on whether the nuclear power plant will start up. The applied methods are introduced briefly along with the most important studies and last but not least as an example of a recently carried out case study, one of the strongest past earthquakes in Austria, the earthquake of 17 July 1670, is presented. The research into historical earthquakes in Austria concentrates on seismic events of the pre-instrumental period. The investigations are not only of historical interest, but also contribute to the completeness and correctness of the Austrian earthquake catalogue, which is the basis for seismic hazard analysis and as such benefits the public, communities, civil engineers, architects, civil protection, and many others.

  19. Modeling strong‐motion recordings of the 2010 Mw 8.8 Maule, Chile, earthquake with high stress‐drop subevents and background slip

    Science.gov (United States)

    Frankel, Arthur

    2017-01-01

    Strong‐motion recordings of the Mw 8.8 Maule earthquake were modeled using a compound rupture model consisting of (1) a background slip distribution with large correlation lengths, relatively low slip velocity, and long peak rise time of slip of about 10 s and (2) high stress‐drop subevents (asperities) on the deeper portion of the rupture with moment magnitudes 7.9–8.2, high slip velocity, and rise times of slip of about 2 s. In this model, the high‐frequency energy is not produced in the same location as the peak coseismic slip, but is generated in the deeper part of the rupture zone. Using synthetic seismograms generated for a plane‐layered velocity model, I find that the high stress‐drop subevents explain the observed Fourier spectral amplitude from about 0.1 to 1.0 Hz. Broadband synthetics (0–10 Hz) were calculated by combining deterministic synthetics derived from the background slip and asperities (≤1  Hz) with stochastic synthetics generated only at the asperities (≥1  Hz). The broadband synthetics produced response spectral accelerations with low bias compared to the data, for periods of 0.1–10 s. A subevent stress drop of 200–350 bars for the high‐frequency stochastic synthetics was found to bracket the observed spectral accelerations at frequencies greater than 1 Hz. For most of the stations, the synthetics had durations of the Arias intensity similar to the observed records.

  20. A novel assessment of odor sources using instrumental analysis combined with resident monitoring records for an industrial area in Korea

    Science.gov (United States)

    Lee, Hyung-Don; Jeon, Soo-Bin; Choi, Won-Joon; Lee, Sang-Sup; Lee, Min-Ho; Oh, Kwang-Joong

    2013-08-01

    The residents living nearby the Sa-sang industrial area (SSIA) continuously were damaged by odorous pollution since 1990s. We determined the concentrations of reduced sulfur compounds (RSCs) [hydrogen sulfide (H2S), methyl mercaptan (CH3SH), dimethyl sulfide (DMS), and dimethyl disulfide (DMDS)], nitrogenous compounds (NCs) [ammonia (NH3) and trimethylamine (TMA)], and carbonyl compounds (CCs) [acetaldehyde and butyraldehyde] by instrumental analysis in the SSIA in Busan, Korea from Jun to Nov, 2011. We determined odor intensity (OI) based on the concentrations of the odorants and resident monitoring records (RMR). The mean concentration of H2S was 10-times higher than NCs, CCs and the other RSC. The contribution from RSCs to the OI was over 50% at all sites excluding the A-5 (chemical production) site. In particular, A-4 (food production) site showed more than 8-times higher the sum of odor activity value (SOAV) than the other sites. This suggested that the A-4 site was the most malodorous area in the SSIA. From the RMR analysis, the annoyance degree (OI ≥ 2) was 51.9% in the industrial area. The 'Rotten' smell arising from the RSCs showed the highest frequency (25.3%) while 'Burned' and 'Other' were more frequent than 'Rotten' in the residential area. The correlation between odor index calculated by instrumental analysis and OI from the RMR was analyzed. The Pearson correlation coefficient (r) of the SOAV was the highest at 0.720 (P food production causes significant annoyance in the SSIA. We also confirm RMR data can be used effectively to evaluate the characteristic of odorants emitted from the SSIA.

  1. Developing a theoretical model and questionnaire survey instrument to measure the success of electronic health records in residential aged care.

    Science.gov (United States)

    Yu, Ping; Qian, Siyu

    2018-01-01

    Electronic health records (EHR) are introduced into healthcare organizations worldwide to improve patient safety, healthcare quality and efficiency. A rigorous evaluation of this technology is important to reduce potential negative effects on patient and staff, to provide decision makers with accurate information for system improvement and to ensure return on investment. Therefore, this study develops a theoretical model and questionnaire survey instrument to assess the success of organizational EHR in routine use from the viewpoint of nursing staff in residential aged care homes. The proposed research model incorporates six variables in the reformulated DeLone and McLean information systems success model: system quality, information quality, service quality, use, user satisfaction and net benefits. Two variables training and self-efficacy were also incorporated into the model. A questionnaire survey instrument was designed to measure the eight variables in the model. After a pilot test, the measurement scale was used to collect data from 243 nursing staff members in 10 residential aged care homes belonging to three management groups in Australia. Partial least squares path modeling was conducted to validate the model. The validated EHR systems success model predicts the impact of the four antecedent variables-training, self-efficacy, system quality and information quality-on the net benefits, the indicator of EHR systems success, through the intermittent variables use and user satisfaction. A 24-item measurement scale was developed to quantitatively evaluate the performance of an EHR system. The parsimonious EHR systems success model and the measurement scale can be used to benchmark EHR systems success across organizations and units and over time.

  2. Stress Regime in the Nepalese Himalaya from Recent Earthquakes.

    Science.gov (United States)

    Pant, M.; Karplus, M. S.; Velasco, A. A.; Nabelek, J.; Kuna, V. M.; Ghosh, A.; Mendoza, M.; Adhikari, L. B.; Sapkota, S. N.; Klemperer, S. L.; Patlan, E.

    2017-12-01

    The two recent earthquakes, April 25, 2015 Mw 7.8 (Gorkha earthquake) and May 12, 2015 Mw 7.2, at the Indo-Eurasian plate margin killed thousands of people and caused billion dollars of property loss. In response to these events, we deployed a dense array of seismometers to record the aftershocks along Gorkha earthquake rupture area. Our network NAMASTE (Nepal Array Measuring Aftershock Seismicity Trailing Earthquake) included 45 different seismic stations (16 short period, 25 broadband, and 4 strong motion sensors) covering a large area from north-central Nepal to south of the Main Frontal Thrust at a spacing of 20 km. The instruments recorded aftershocks from June 2015 to May 2016. We used time domain short term average (STA) and long term average (LTA) algorithms (1/10s and 4/40s) respectively to detect the arrivals and then developed an earthquake catalog containing 9300 aftershocks. We are manually picking the P-wave first motion arrival polarity to develop a catalog of focal mechanisms for the larger magnitude (>M3.0) events with adequate (>10) arrivals. We hope to characterize the seismicity and stress mechanisms of the complex fault geometries in the Nepalese Himalaya and to address the geophysical processes controlling seismic cycles in the Indo-Eurasian plate margin.

  3. Deterministic earthquake scenarios for the city of Sofia

    CERN Document Server

    Slavov, S I; Panza, G F; Paskaleva, I; Vaccari, P

    2002-01-01

    The city of Sofia is exposed to a high seismic risk. Macroseismic intensities in the range of VIII-X (MSK) can be expected in the city. The earthquakes, that can influence the hazard at Sofia, originate either beneath the city or are caused by seismic sources located within a radius of 40km. The city of Sofia is also prone to the remote Vrancea seismic zone in Romania, and particularly vulnerable are the long - period elements of the built environment. The high seismic risk and the lack of instrumental recordings of the regional seismicity makes the use of appropriate credible earthquake scenarios and ground motion modelling approaches for defining the seismic input for the city of Sofia necessary. Complete synthetic seismic signals, due to several earthquake scenarios, were computed along chosen geological profiles crossing the city, applying a hybrid technique, based on the modal summation technique and finite differences. The modelling takes into account simultaneously the geotechnical properties of the si...

  4. A Jurassic Shock-Aftershock Earthquake Sequence Recorded by Small Clastic Pipes and Dikes within Dune Cross-Strata, Zion National Park, Utah

    Science.gov (United States)

    Loope, D. B.; Zlotnik, V. A.; Kettler, R. M.; Pederson, D. T.

    2012-12-01

    dune lee slope through a pipe, the erupted sand dried and was buried by climbing wind-ripple strata as the large dune continued to advance downwind. The mapped cluster recording eight distinct seismic events lies within thin-laminated sediment that was deposited by wind ripples during 1 m (~ 1 year) of southeastward dune migration. We conclude that the small pipes and dikes of our study sites are products of numerous >MM 5 earthquakes, some of which recurred at intervals of less than 2 months. We interpret one small cluster of pipes and dikes with well-defined upward terminations as a distinct shock-aftershock sequence. Because the largest modern earthquakes can produce surface liquefaction only up to about 175 km from their epicenters, the Jurassic epicenters must have been well within that distance. The tendency of modern plate boundaries to produce high-frequency aftershocks suggests that the epicenter for this Jurassic sequence lay to the southwest, within the plate boundary zone (not within continental rocks to the east). As eolian dunes steadily migrate over interdune surfaces underlain by water-saturated dune cross-strata, the thin, distinct laminae produced by the wind ripples that occupy dune toes can faithfully record high-frequency seismic events.

  5. Rupture history of the 2011 M 9 Tohoku Japan earthquake determined from strong‐motion and high‐rate GPS recordings: Subevents radiating energy in different frequency bands

    Science.gov (United States)

    Frankel, Arthur

    2013-01-01

    Strong‐motion records from KiK‐net and K‐NET, along with 1 sample/s Global Positioning System (GPS) records from GEONET, were analyzed to determine the location, timing, and slip of subevents of the M 9 2011 Tohoku earthquake. Timing of arrivals on stations along the coast shows that the first subevent was located closer to the coast than subevent (2), which produced the largest slip. A waveform inversion of data from 0 to 0.2 Hz indicates that the first subevent primarily ruptured down‐dip and north of the hypocenter and had an M of 8.5. The areas of this subevent that generated the low (0.2  Hz) frequency energy are located in the same vicinity. The inversion result for the second subevent (M 9.0) has large slip on the shallow part of the fault with peak slip of about 65 m above about 25 km depth. This slip generated the tsunami. The preferred inversion has initiation of subevent 2 on the shallow portion of the fault so that rupture proceeded down‐dip and mainly to the south. Subevent 2 started about 35 s after subevent 1, which allows for the possibility of dynamic triggering from subevent 1. The slip model predicts displacements comparable to those found from ocean‐bottom transducers near the epicenter. At frequencies that most affect tall buildings (0.1–0.5 Hz), there is a strong pulse (subevent 3) in the strong‐motion records that arrives after the near‐field ramp from subevent 2. High‐frequency subevent 3 was located down‐dip and south of the high‐slip portion of subevent 2 and was initiated as rupture from subevent 2 proceeded down‐dip. The compact pulse for subevent 3 is modeled with an M 8.0 source in a 75 by 30 km area that ruptured down‐dip and to the south with a high slip velocity, indicating high stress drop.

  6. Earthquake hazard assessment and small earthquakes

    International Nuclear Information System (INIS)

    Reiter, L.

    1987-01-01

    The significance of small earthquakes and their treatment in nuclear power plant seismic hazard assessment is an issue which has received increased attention over the past few years. In probabilistic studies, sensitivity studies showed that the choice of the lower bound magnitude used in hazard calculations can have a larger than expected effect on the calculated hazard. Of particular interest is the fact that some of the difference in seismic hazard calculations between the Lawrence Livermore National Laboratory (LLNL) and Electric Power Research Institute (EPRI) studies can be attributed to this choice. The LLNL study assumed a lower bound magnitude of 3.75 while the EPRI study assumed a lower bound magnitude of 5.0. The magnitudes used were assumed to be body wave magnitudes or their equivalents. In deterministic studies recent ground motion recordings of small to moderate earthquakes at or near nuclear power plants have shown that the high frequencies of design response spectra may be exceeded. These exceedances became important issues in the licensing of the Summer and Perry nuclear power plants. At various times in the past particular concerns have been raised with respect to the hazard and damage potential of small to moderate earthquakes occurring at very shallow depths. In this paper a closer look is taken at these issues. Emphasis is given to the impact of lower bound magnitude on probabilistic hazard calculations and the historical record of damage from small to moderate earthquakes. Limited recommendations are made as to how these issues should be viewed

  7. Bridge seismic retrofit measures considering subduction zone earthquakes.

    Science.gov (United States)

    2015-07-01

    Over the years, earthquakes have exposed the vulnerability of reinforced concrete structures under : seismic loads. The recent occurrence of highly devastating earthquakes near instrumented regions, e.g. 2010 Maule, Chile : and 2011 Tohoku, Japan, ha...

  8. Geophysical Anomalies and Earthquake Prediction

    Science.gov (United States)

    Jackson, D. D.

    2008-12-01

    Finding anomalies is easy. Predicting earthquakes convincingly from such anomalies is far from easy. Why? Why have so many beautiful geophysical abnormalities not led to successful prediction strategies? What is earthquake prediction? By my definition it is convincing information that an earthquake of specified size is temporarily much more likely than usual in a specific region for a specified time interval. We know a lot about normal earthquake behavior, including locations where earthquake rates are higher than elsewhere, with estimable rates and size distributions. We know that earthquakes have power law size distributions over large areas, that they cluster in time and space, and that aftershocks follow with power-law dependence on time. These relationships justify prudent protective measures and scientific investigation. Earthquake prediction would justify exceptional temporary measures well beyond those normal prudent actions. Convincing earthquake prediction would result from methods that have demonstrated many successes with few false alarms. Predicting earthquakes convincingly is difficult for several profound reasons. First, earthquakes start in tiny volumes at inaccessible depth. The power law size dependence means that tiny unobservable ones are frequent almost everywhere and occasionally grow to larger size. Thus prediction of important earthquakes is not about nucleation, but about identifying the conditions for growth. Second, earthquakes are complex. They derive their energy from stress, which is perniciously hard to estimate or model because it is nearly singular at the margins of cracks and faults. Physical properties vary from place to place, so the preparatory processes certainly vary as well. Thus establishing the needed track record for validation is very difficult, especially for large events with immense interval times in any one location. Third, the anomalies are generally complex as well. Electromagnetic anomalies in particular require

  9. Dynamic strains for earthquake source characterization

    Science.gov (United States)

    Barbour, Andrew J.; Crowell, Brendan W

    2017-01-01

    Strainmeters measure elastodynamic deformation associated with earthquakes over a broad frequency band, with detection characteristics that complement traditional instrumentation, but they are commonly used to study slow transient deformation along active faults and at subduction zones, for example. Here, we analyze dynamic strains at Plate Boundary Observatory (PBO) borehole strainmeters (BSM) associated with 146 local and regional earthquakes from 2004–2014, with magnitudes from M 4.5 to 7.2. We find that peak values in seismic strain can be predicted from a general regression against distance and magnitude, with improvements in accuracy gained by accounting for biases associated with site–station effects and source–path effects, the latter exhibiting the strongest influence on the regression coefficients. To account for the influence of these biases in a general way, we include crustal‐type classifications from the CRUST1.0 global velocity model, which demonstrates that high‐frequency strain data from the PBO BSM network carry information on crustal structure and fault mechanics: earthquakes nucleating offshore on the Blanco fracture zone, for example, generate consistently lower dynamic strains than earthquakes around the Sierra Nevada microplate and in the Salton trough. Finally, we test our dynamic strain prediction equations on the 2011 M 9 Tohoku‐Oki earthquake, specifically continuous strain records derived from triangulation of 137 high‐rate Global Navigation Satellite System Earth Observation Network stations in Japan. Moment magnitudes inferred from these data and the strain model are in agreement when Global Positioning System subnetworks are unaffected by spatial aliasing.

  10. A geological evidence of very low frequency earthquake inferred from vitrinite thermal records across a microfault within on-land accretionary complex.

    Science.gov (United States)

    Morita, K.; Hashimoto, Y.; Hirose, T.; Hamada, Y.; Kitamura, M.

    2014-12-01

    Generation of friction heat associated with fault slip is controlled by friction, slip distance and fault thickness. Nature of fault slip can be estimated from the record of frictional heating along a fault (e.g., Fulton et al., 2012). Purpose of this study is to detect the record of frictional heating along a microfault observed in on-land accretionary complex, Shimanto Belt, SW Japan using vitrinite reflectance (Ro) and to examine the characteristics of fault slip in deeper subduction zone. The study area is located in Nonokawa formation, the Cretaceous Shimanto Belt, in Kochi Prefecture, Southwest Japan. We found a carbonaceous material concentrated layer (CMCL) in the formation. Some micro-faults cut the layer. The thickness of CMCL is about 3-4m. Ro of host rock is about 0.98-1.1% and of fault rock is over 1.2%. Kitamura et al. (2012) pointed out that fracturing energy may control the high Ro within fault zone. To avoid the effect of fracturing on Ro, we tired to detect a diffusion pattern of frictional heating in host rocks. Distribution of Ro is mapped in thin sections to make the Ro-distance pattern perpendicular to the fault plane. Within the fracture zone, abnormally high Ro (about 2.0% or above) was observed. Ro was 1.25% at the wall of fracture zone and decreases to 1.1% at about 5cm from the wall. We interpreted that the Ro-distance pattern was resulted from the thermal diffusion. Using this diffusion pattern, the characteristic fault parameters, such as friction, slip rate and rise time (Tr) was examined. We set parameters Q (= friction times slip rate). We have simulated frictional heating and Ro maturation on the basis of the method by Sweeny and Burnham (1990). Grid search was conducted to find the best fitted combination of Q and Tr at the smallest residual between simulated Ro and observed Ro. In the result, we estimated about 1500 (Pa m/s) of Q and about 130000(s) of Tr. Because the base temperature is about 185˚C based on the 1.1% of Ro, the

  11. Treating pre-instrumental data as "missing" data: using a tree-ring-based paleoclimate record and imputations to reconstruct streamflow in the Missouri River Basin

    Science.gov (United States)

    Ho, M. W.; Lall, U.; Cook, E. R.

    2015-12-01

    Advances in paleoclimatology in the past few decades have provided opportunities to expand the temporal perspective of the hydrological and climatological variability across the world. The North American region is particularly fortunate in this respect where a relatively dense network of high resolution paleoclimate proxy records have been assembled. One such network is the annually-resolved Living Blended Drought Atlas (LBDA): a paleoclimate reconstruction of the Palmer Drought Severity Index (PDSI) that covers North America on a 0.5° × 0.5° grid based on tree-ring chronologies. However, the use of the LBDA to assess North American streamflow variability requires a model by which streamflow may be reconstructed. Paleoclimate reconstructions have typically used models that first seek to quantify the relationship between the paleoclimate variable and the environmental variable of interest before extrapolating the relationship back in time. In contrast, the pre-instrumental streamflow is here considered as "missing" data. A method of imputing the "missing" streamflow data, prior to the instrumental record, is applied through multiple imputation using chained equations for streamflow in the Missouri River Basin. In this method, the distribution of the instrumental streamflow and LBDA is used to estimate sets of plausible values for the "missing" streamflow data resulting in a ~600 year-long streamflow reconstruction. Past research into external climate forcings, oceanic-atmospheric variability and its teleconnections, and assessments of rare multi-centennial instrumental records demonstrate that large temporal oscillations in hydrological conditions are unlikely to be captured in most instrumental records. The reconstruction of multi-centennial records of streamflow will enable comprehensive assessments of current and future water resource infrastructure and operations under the existing scope of natural climate variability.

  12. Introduction to thematic collection "Historical and geological studies of earthquakes"

    Science.gov (United States)

    Satake, Kenji; Wang, Jian; Hammerl, Christa; Malik, Javed N.

    2017-12-01

    This thematic collection contains eight papers mostly presented at the 2016 AOGS meeting in Beijing. Four papers describe historical earthquake studies in Europe, Japan, and China; one paper uses modern instrumental data to examine the effect of giant earthquakes on the seismicity rate; and three papers describe paleoseismological studies using tsunami deposit in Japan, marine terraces in Philippines, and active faults in Himalayas. Hammerl (Geosci Lett 4:7, 2017) introduced historical seismological studies in Austria, starting from methodology which is state of the art in most European countries, followed by a case study for an earthquake of July 17, 1670 in Tyrol. Albini and Rovida (Geosci Lett 3:30, 2016) examined 114 historical records for the earthquake on April 6, 1667 on the east coast of the Adriatic Sea, compiled 37 Macroseismic Data Points, and estimated the epicenter and the size of the earthquake. Matsu'ura (Geosci Lett 4:3, 2017) summarized historical earthquake studies in Japan which resulted in about 8700 Intensity Data Points, assigned epicenters for 214 earthquakes between AD 599 and 1872, and estimated focal depth and magnitudes for 134 events. Wang et al. (Geosci Lett 4:4, 2017) introduced historical seismology in China, where historical earthquake archives include about 15,000 sources, and parametric catalogs include about 1000 historical earthquakes between 2300 BC and AD 1911. Ishibe et al. (Geosci Lett 4:5, 2017) tested the Coulomb stress triggering hypothesis for three giant (M 9) earthquakes that occurred in recent years, and found that at least the 2004 Sumatra-Andaman and 2011 Tohoku earthquakes caused the seismicity rate change. Ishimura (2017) re-estimated the ages of 11 tsunami deposits in the last 4000 years along the Sanriku coast of northern Japan and found that the average recurrence interval of those tsunamis as 350-390 years. Ramos et al. (2017) studied 1000-year-old marine terraces on the west coast of Luzon Island, Philippines

  13. Sediment gravity flows triggered by remotely generated earthquake waves

    Science.gov (United States)

    Johnson, H. Paul; Gomberg, Joan S.; Hautala, Susan L.; Salmi, Marie S.

    2017-06-01

    Recent great earthquakes and tsunamis around the world have heightened awareness of the inevitability of similar events occurring within the Cascadia Subduction Zone of the Pacific Northwest. We analyzed seafloor temperature, pressure, and seismic signals, and video stills of sediment-enveloped instruments recorded during the 2011-2015 Cascadia Initiative experiment, and seafloor morphology. Our results led us to suggest that thick accretionary prism sediments amplified and extended seismic wave durations from the 11 April 2012 Mw8.6 Indian Ocean earthquake, located more than 13,500 km away. These waves triggered a sequence of small slope failures on the Cascadia margin that led to sediment gravity flows culminating in turbidity currents. Previous studies have related the triggering of sediment-laden gravity flows and turbidite deposition to local earthquakes, but this is the first study in which the originating seismic event is extremely distant (> 10,000 km). The possibility of remotely triggered slope failures that generate sediment-laden gravity flows should be considered in inferences of recurrence intervals of past great Cascadia earthquakes from turbidite sequences. Future similar studies may provide new understanding of submarine slope failures and turbidity currents and the hazards they pose to seafloor infrastructure and tsunami generation in regions both with and without local earthquakes.

  14. Novel seismic instrumentation for nuclear power plants

    International Nuclear Information System (INIS)

    Bolleter, W.; Savary, C.

    1998-01-01

    Conforming to the latest issues of the Nuclear Regulatory Commission Regulatory Guide, a novel hardware and software solution for seismic instrumentation is presented. Both instrumentation and PC-based data evaluation software for post-earthquake actions are type-tested and approved by the German TUeV. Reference installations replacing obsolete analog instrumentation were successfully completed and are presented. The instrumentation consists of highly linear, solid-state capacitive accelerometers as well as digital recorders storing the signals from the sensors in situ. These recorders are linked in a star-topology network to a central unit that permanently communicates with them via fiber-optic cable or current-loop links. The central unit is responsible for alerting and synchronizes all recorders which otherwise act autonomously. Data evaluation is handled by a PC-based software package. It includes automatic data evaluation after earthquakes (batch mode), interactive data evaluation software for detailed data analysis, and software tools for remote operation, maintenance and data storage. (author)

  15. Database for earthquake strong motion studies in Italy

    Science.gov (United States)

    Scasserra, G.; Stewart, J.P.; Kayen, R.E.; Lanzo, G.

    2009-01-01

    We describe an Italian database of strong ground motion recordings and databanks delineating conditions at the instrument sites and characteristics of the seismic sources. The strong motion database consists of 247 corrected recordings from 89 earthquakes and 101 recording stations. Uncorrected recordings were drawn from public web sites and processed on a record-by-record basis using a procedure utilized in the Next-Generation Attenuation (NGA) project to remove instrument resonances, minimize noise effects through low- and high-pass filtering, and baseline correction. The number of available uncorrected recordings was reduced by 52% (mostly because of s-triggers) to arrive at the 247 recordings in the database. The site databank includes for every recording site the surface geology, a measurement or estimate of average shear wave velocity in the upper 30 m (Vs30), and information on instrument housing. Of the 89 sites, 39 have on-site velocity measurements (17 of which were performed as part of this study using SASW techniques). For remaining sites, we estimate Vs30 based on measurements on similar geologic conditions where available. Where no local velocity measurements are available, correlations with surface geology are used. Source parameters are drawn from databanks maintained (and recently updated) by Istituto Nazionale di Geofisica e Vulcanologia and include hypocenter location and magnitude for small events (M< ??? 5.5) and finite source parameters for larger events. ?? 2009 A.S. Elnashai & N.N. Ambraseys.

  16. Responses of a tall building with U.S. code-type instrumentation in Tokyo, Japan, to events before, during and after the Tohoku earthquake of 11 March 2011

    Science.gov (United States)

    Çelebi, Mehmet; Kashima, Toshihide; Ghahari, S. Farid; Abazarsa, Fariba; Taciroglu, Ertugrul

    2016-01-01

    The 11 March 2011 M 9.0 Tohoku earthquake generated long-duration shaking that propagated hundreds of kilometers from the epicenter and affected tall buildings in urban areas several hundred kilometers from the epicenter of the main shock. Recorded responses show that tall buildings were affected by long-period motions. This study presents the behavior and performance of a 37-story building in the Tsukuda area of Tokyo, Japan, as inferred from modal analyses of records retrieved for a time interval covering a few days before, during, and for several months after the main shock. The U.S. “code-type” array comprises three triaxial accelerometers deployed at three levels in the superstructure. Such a sparse array in a tall structure limits a reliable assessment, because its performance must be based on only the average drift ratios. Based on the inferred values of this parameter, the subject building was not structurally damaged.

  17. Earthquake-induced soft-sediment deformations and seismically amplified erosion rates recorded in varved sediments of Köyceğiz Lake (SW Turkey)

    KAUST Repository

    Avsar, Ulas

    2016-06-06

    Earthquake-triggered landslides amplify erosion rates in catchments, i.e. catchment response to seismic shocks (CR). In addition to historical eyewitness accounts of muddy rivers implying CRs after large earthquakes, several studies have quantitatively reported increased sediment concentrations in rivers after earthquakes. However, only a few paleolimnological studies could detect CRs within lacustrine sedimentary sequences as siliciclastic-enriched intercalations within background sedimentation. Since siliciclastic-enriched intercalations can easily be of non-seismic origin, their temporal correlation with nearby earthquakes is crucial to assign a seismic triggering mechanism. In most cases, either uncertainties in dating methods or the lack of recent seismic activity has prevented reliable temporal correlations, making the seismic origin of observed sedimentary events questionable. Here, we attempt to remove this question mark by presenting sedimentary traces of CRs in the 370-year-long varved sequence of Köyceğiz Lake (SW Turkey) that we compare with estimated peak ground acceleration (PGA) values of several nearby earthquakes. We find that earthquakes exceeding estimated PGA values of ca. 20 cm/s2 can induce soft-sediment deformations (SSD), while CRs seem only to be triggered by PGA levels higher than 70 cm/s2. In Köyceğiz Lake, CRs produce Cr- and Ni-enriched sedimentation due to the seismically mobilized soils derived from ultramafic rocks in the catchment. Given the varve chronology, the residence time of the seismically mobilized material in the catchment is determined to be 5 to 10 years.

  18. Static stress drop of the largest recorded M 4.6 hydraulic fracturing induced earthquake and its aftershock pattern in the northern Montney Play, British Columbia, Canada

    Science.gov (United States)

    Wang, B.; Harrington, R. M.; Liu, Y.; Kao, H.

    2016-12-01

    The largest suspected fracking-induced earthquake to date occurred near Fort St. John, British Columbia on August 17, 2015, with a reported magnitude of Mw 4.6. Here we estimate the static stress released by the mainshock and the five cataloged aftershocks using new data from eight broadband seismometers installed approximately 50km from the hypocenter of the mainshock, at distances much closer than the Natural Resources Canada regional seismic stations. The estimated cross-correlation coefficient among the 5 cataloged earthquakes is 0.35 or greater. We will present seismic moment (M0) and spectral corner frequency (fc) values estimated using both individual earthquake spectra and spectral ratios to correct for travel-path attenuation and site effects. Static stress drop and scaled energy value calculations based on the estimated moment and corner frequency values will be presented, as well as focal mechanisms for the largest events with adequate station coverage. We will also use a multi-station matched-filter approach to detect additional uncataloged earthquakes on continuous waveforms for a period of two months after the mainshock. Using the results of the matched-filter approach, we will present the aftershock magnitude distribution and locations. The results of our detection and location calculations will be compared to reported fracking parameters, such as fluid injection pressure and duration, to determine their correlation with the spatial and temporal distribution of aftershocks. The objective of this study is to relate operational parameters to earthquake occurrence in order to help to develop procedures to understand the mechanisms responsible for fracking induced earthquakes, their relation to the maximum induced magnitude, and to reduce potential hazards of anthropogenically induced seismic activity.

  19. The Pawnee earthquake as a result of the interplay among injection, faults and foreshocks.

    Science.gov (United States)

    Chen, Xiaowei; Nakata, Nori; Pennington, Colin; Haffener, Jackson; Chang, Jefferson C; He, Xiaohui; Zhan, Zhongwen; Ni, Sidao; Walter, Jacob I

    2017-07-10

    The Pawnee M5.8 earthquake is the largest event in Oklahoma instrument recorded history. It occurred near the edge of active seismic zones, similar to other M5+ earthquakes since 2011. It ruptured a previously unmapped fault and triggered aftershocks along a complex conjugate fault system. With a high-resolution earthquake catalog, we observe propagating foreshocks leading to the mainshock within 0.5 km distance, suggesting existence of precursory aseismic slip. At approximately 100 days before the mainshock, two M ≥ 3.5 earthquakes occurred along a mapped fault that is conjugate to the mainshock fault. At about 40 days before, two earthquakes clusters started, with one M3 earthquake occurred two days before the mainshock. The three M ≥ 3 foreshocks all produced positive Coulomb stress at the mainshock hypocenter. These foreshock activities within the conjugate fault system are near-instantaneously responding to variations in injection rates at 95% confidence. The short time delay between injection and seismicity differs from both the hypothetical expected time scale of diffusion process and the long time delay observed in this region prior to 2016, suggesting a possible role of elastic stress transfer and critical stress state of the fault. Our results suggest that the Pawnee earthquake is a result of interplay among injection, tectonic faults, and foreshocks.

  20. Archiving, sharing, processing and publishing historical earthquakes data: the IT point of view

    Science.gov (United States)

    Locati, Mario; Rovida, Andrea; Albini, Paola

    2014-05-01

    Digital tools devised for seismological data are mostly designed for handling instrumentally recorded data. Researchers working on historical seismology are forced to perform their daily job using a general purpose tool and/or coding their own to address their specific tasks. The lack of out-of-the-box tools expressly conceived to deal with historical data leads to a huge amount of time lost in performing tedious task to search for the data and, to manually reformat it in order to jump from one tool to the other, sometimes causing a loss of the original data. This reality is common to all activities related to the study of earthquakes of the past centuries, from the interpretations of past historical sources, to the compilation of earthquake catalogues. A platform able to preserve the historical earthquake data, trace back their source, and able to fulfil many common tasks was very much needed. In the framework of two European projects (NERIES and SHARE) and one global project (Global Earthquake History, GEM), two new data portals were designed and implemented. The European portal "Archive of Historical Earthquakes Data" (AHEAD) and the worldwide "Global Historical Earthquake Archive" (GHEA), are aimed at addressing at least some of the above mentioned issues. The availability of these new portals and their well-defined standards makes it easier than before the development of side tools for archiving, publishing and processing the available historical earthquake data. The AHEAD and GHEA portals, their underlying technologies and the developed side tools are presented.

  1. Swedish earthquakes and acceleration probabilities

    International Nuclear Information System (INIS)

    Slunga, R.

    1979-03-01

    A method to assign probabilities to ground accelerations for Swedish sites is described. As hardly any nearfield instrumental data is available we are left with the problem of interpreting macroseismic data in terms of acceleration. By theoretical wave propagation computations the relation between seismic strength of the earthquake, focal depth, distance and ground accelerations are calculated. We found that most Swedish earthquake of the area, the 1904 earthquake 100 km south of Oslo, is an exception and probably had a focal depth exceeding 25 km. For the nuclear power plant sites an annual probability of 10 -5 has been proposed as interesting. This probability gives ground accelerations in the range 5-20 % for the sites. This acceleration is for a free bedrock site. For consistency all acceleration results in this study are given for bedrock sites. When applicating our model to the 1904 earthquake and assuming the focal zone to be in the lower crust we get the epicentral acceleration of this earthquake to be 5-15 % g. The results above are based on an analyses of macrosismic data as relevant instrumental data is lacking. However, the macroseismic acceleration model deduced in this study gives epicentral ground acceleration of small Swedish earthquakes in agreement with existent distant instrumental data. (author)

  2. Deterministic Earthquake Hazard Assessment by Public Agencies in California

    Science.gov (United States)

    Mualchin, L.

    2005-12-01

    Even in its short recorded history, California has experienced a number of damaging earthquakes that have resulted in new codes and other legislation for public safety. In particular, the 1971 San Fernando earthquake produced some of the most lasting results such as the Hospital Safety Act, the Strong Motion Instrumentation Program, the Alquist-Priolo Special Studies Zone Act, and the California Department of Transportation (Caltrans') fault-based deterministic seismic hazard (DSH) map. The latter product provides values for earthquake ground motions based on Maximum Credible Earthquakes (MCEs), defined as the largest earthquakes that can reasonably be expected on faults in the current tectonic regime. For surface fault rupture displacement hazards, detailed study of the same faults apply. Originally, hospital, dam, and other critical facilities used seismic design criteria based on deterministic seismic hazard analyses (DSHA). However, probabilistic methods grew and took hold by introducing earthquake design criteria based on time factors and quantifying "uncertainties", by procedures such as logic trees. These probabilistic seismic hazard analyses (PSHA) ignored the DSH approach. Some agencies were influenced to adopt only the PSHA method. However, deficiencies in the PSHA method are becoming recognized, and the use of the method is now becoming a focus of strong debate. Caltrans is in the process of producing the fourth edition of its DSH map. The reason for preferring the DSH method is that Caltrans believes it is more realistic than the probabilistic method for assessing earthquake hazards that may affect critical facilities, and is the best available method for insuring public safety. Its time-invariant values help to produce robust design criteria that are soundly based on physical evidence. And it is the method for which there is the least opportunity for unwelcome surprises.

  3. Awareness and understanding of earthquake hazards at school

    Science.gov (United States)

    Saraò, Angela; Peruzza, Laura; Barnaba, Carla; Bragato, Pier Luigi

    2014-05-01

    Schools have a fundamental role in broadening the understanding of natural hazard and risks and in building the awareness in the community. Recent earthquakes in Italy and worldwide, have clearly demonstrated that the poor perception of seismic hazards diminishes the effectiveness of mitigation countermeasures. Since years the Seismology's department of OGS is involved in education projects and public activities to raise awareness about earthquakes. Working together with teachers we aim at developing age-appropriate curricula to improve the student's knowledge about earthquakes, seismic safety, and seismic risk reduction. Some examples of education activities we performed during the last years are here presented. We show our experience with the primary and intermediate schools where, through hands-on activities, we explain the earthquake phenomenon and its effects to kids, but we illustrate also some teaching interventions for high school students. During the past years we lectured classes, we led laboratory and field activities, and we organized summer stages for selected students. In the current year we are leading a project aimed at training high school students on seismic safety through a multidisciplinary approach that involves seismologists, engineers and experts of safety procedures. To combine the objective of dissemination of earthquake culture, also through the knowledge of the past seismicity, with that of a safety culture, we use innovative educational techniques and multimedia resources. Students and teachers, under the guidance of an expert seismologist, organize a combination of hands-on activities for understanding earthquakes in the lab through cheap tools and instrumentations At selected schools we provided the low cost seismometers of the QuakeCatcher network (http://qcn.stanford.edu) for recording earthquakes, and we trained teachers to use such instruments in the lab and to analyze recorded data. Within the same project we are going to train

  4. Testing earthquake source inversion methodologies

    KAUST Repository

    Page, Morgan T.

    2011-01-01

    Source Inversion Validation Workshop; Palm Springs, California, 11-12 September 2010; Nowadays earthquake source inversions are routinely performed after large earthquakes and represent a key connection between recorded seismic and geodetic data and the complex rupture process at depth. The resulting earthquake source models quantify the spatiotemporal evolution of ruptures. They are also used to provide a rapid assessment of the severity of an earthquake and to estimate losses. However, because of uncertainties in the data, assumed fault geometry and velocity structure, and chosen rupture parameterization, it is not clear which features of these source models are robust. Improved understanding of the uncertainty and reliability of earthquake source inversions will allow the scientific community to use the robust features of kinematic inversions to more thoroughly investigate the complexity of the rupture process and to better constrain other earthquakerelated computations, such as ground motion simulations and static stress change calculations.

  5. A procedure for assessing seismic hazard generated by Vrancea earthquakes and its application. III. A method for developing isoseismal and isoacceleration maps. Applications

    International Nuclear Information System (INIS)

    Enescu, D.; Enescu, B.D.

    2007-01-01

    A method for developing isoseismal and isoacceleration maps assumedly valid for future strong earthquakes (M GR > 6.7) is described as constituting the third stage of a procedure for assessing the seismic hazard generated by Vrancea earthquakes. The method relies on the results of the former two stages given by Enescu et al., and on further developments that are presented in this paper. Moreover, it is based on instrument recording data. Major earthquakes taking place in Vrancea (November 10, 1940 - M GR 7.4, March 4, 1977 - M GR = 7.2 and the strongest possible) were examined as a way to test the method. The method is also applied for an earthquake of magnitude M GR = 6.7. Given the successful results of the tests, the method can by used for predicting isoseismal and isoacceleration maps for future Vrancea earthquakes of various magnitudes M GR ≥ 6.7. (authors)

  6. Estimation of seismic velocity changes at different depths associated with the 2014 Northern Nagano Prefecture earthquake, Japan ( M W 6.2) by joint interferometric analysis of NIED Hi-net and KiK-net records

    Science.gov (United States)

    Sawazaki, Kaoru; Saito, Tatsuhiko; Ueno, Tomotake; Shiomi, Katsuhiko

    2016-12-01

    To estimate the seismic velocity changes at different depths associated with a large earthquake, we apply passive image interferometry to two types of seismograms: KiK-net vertical pairs of earthquake records and Hi-net continuous borehole data. We compute the surface/borehole deconvolution waveform (DCW) of seismograms recorded by a KiK-net station and the autocorrelation function (ACF) of ambient noise recorded by a collocated Hi-net station, 26 km from the epicenter of the 2014 Northern Nagano Prefecture earthquake, Japan ( M W 6.2). Because the deeper KiK-net sensor and the Hi-net sensor are collocated at 150 m depth, and another KiK-net sensor is located at the surface directly above the borehole sensors, we can measure shallow (150 m depth) velocity changes separately. The sensitivity of the ACF to the velocity changes in the deeper zone is evaluated by a numerical wave propagation simulation. We detect relative velocity changes of -3.1 and -1.4% in the shallow and deep zones, respectively, within 1 week of the mainshock. The relative velocity changes recover to -1.9 and -1.1%, respectively, during the period between 1 week and 4 months after the mainshock. The observed relative velocity reductions can be attributed to dynamic strain changes due to the strong ground motion, rather than static strain changes due to coseismic deformation by the mainshock. The speed of velocity recovery may be faster in the shallow zone than in the deep zone because the recovery speed is controlled by initial damage in the medium. This recovery feature is analogous to the behavior of slow dynamics observed in rock experiments.

  7. Evaluation of a Nutrition Care Process-based audit instrument, the Diet-NCP-Audit, for documentation of dietetic care in medical records.

    Science.gov (United States)

    Lövestam, Elin; Orrevall, Ylva; Koochek, Afsaneh; Karlström, Brita; Andersson, Agneta

    2014-06-01

    Adequate documentation in medical records is important for high-quality health care. Documentation quality is widely studied within nursing, but studies are lacking within dietetic care. The aim of this study was to translate, elaborate and evaluate an audit instrument, based on the four-step Nutrition Care Process model, for documentation of dietetic care in medical records. The audit instrument includes 14 items focused on essential parts of dietetic care and the documentation's clarity and structure. Each item is to be rated 0-1 or 0-2 points, with a maximum total instrument score of 26. A detailed manual was added to facilitate the interpretation and increase the reliability of the instrument. The instrument is based on a similar tool initiated 9 years ago in the United States, which in this study was translated to Swedish and further elaborated. The translated and further elaborated instrument was named Diet-NCP-Audit. Firstly, the content validity of the Diet-NCP-Audit instrument was tested by five experienced dietitians. They rated the relevance and clarity of the included items. After a first rating, minor improvements were made. After the second rating, the Content Validity Indexes were 1.0, and the Clarity Index was 0.98. Secondly, to test the reliability, four dietitians reviewed 20 systematically collected dietetic notes independently using the audit instrument. Before the review, a calibration process was performed. A comparison of the reviews was performed, which resulted in a moderate inter-rater agreement with Krippendorff's α = 0.65-0.67. Grouping the audit results in three levels: lower, medium or higher range, a Krippendorff's α of 0.74 was considered high reliability. Also, an intra-rater reliability test-retest with a 9 weeks interval, performed by one dietitian, showed strong agreement. To conclude, the evaluated audit instrument had high content validity and moderate to high reliability and can be used in auditing documentation of dietetic

  8. Interactions between strike-slip earthquakes and the subduction interface near the Mendocino Triple Junction

    Science.gov (United States)

    Gong, Jianhua; McGuire, Jeffrey J.

    2018-01-01

    The interactions between the North American, Pacific, and Gorda plates at the Mendocino Triple Junction (MTJ) create one of the most seismically active regions in North America. The earthquakes rupture all three plate boundaries but also include considerable intraplate seismicity reflecting the strong internal deformation of the Gorda plate. Understanding the stress levels that drive these ruptures and estimating the locking state of the subduction interface are especially important topics for regional earthquake hazard assessment. However owing to the lack of offshore seismic and geodetic instruments, the rupture process of only a few large earthquakes near the MTJ have been studied in detail and the locking state of the subduction interface is not well constrained. In this paper, first, we use the second moments inversion method to study the rupture process of the January 28, 2015 Mw 5.7 earthquake on the Mendocino transform fault that was unusually well recorded by both onshore and offshore strong motion instruments. We estimate the rupture dimension to be approximately 6 km by 3 km corresponding to a stress drop of ∼4 MPa for a crack model. Next we investigate the frictional state of the subduction interface by simulating the afterslip that would be expected there as a result of the stress changes from the 2015 earthquake and a 2010 Mw 6.5 intraplate earthquake within the subducted Gorda plate. We simulate afterslip scenarios for a range of depths of the downdip end of the locked zone defined as the transition to velocity strengthening friction and calculate the corresponding surface deformation expected at onshore GPS monuments. We can rule out a very shallow downdip limit owing to the lack of a detectable signal at onshore GPS stations following the 2010 earthquake. Our simulations indicate that the locking depth on the slab surface is at least 14 km, which suggests that the next M8 earthquake rupture will likely reach the coastline and strong shaking

  9. Recorded motions of the 6 April 2009 Mw 6.3 L'Aquila, Italy, earthquake and implications for building structural damage: Overview

    Science.gov (United States)

    Celebi, M.; Bazzurro, P.; Chiaraluce, L.; Clemente, P.; Decanini, L.; Desortis, A.; Ellsworth, W.; Gorini, A.; Kalkan, E.; Marcucci, S.; Milana, G.; Mollaioli, F.; Olivieri, M.; Paolucci, R.; Rinaldis, D.; Rovelli, A.; Sabetta, F.; Stephens, C.

    2010-01-01

    The normal-faulting earthquake of 6 April 2009 in the Abruzzo Region of central Italy caused heavy losses of life and substantial damage to centuriesold buildings of significant cultural importance and to modern reinforcedconcrete- framed buildings with hollow masonry infill walls. Although structural deficiencies were significant and widespread, the study of the characteristics of strong motion data from the heavily affected area indicated that the short duration of strong shaking may have spared many more damaged buildings from collapsing. It is recognized that, with this caveat of shortduration shaking, the infill walls may have played a very important role in preventing further deterioration or collapse of many buildings. It is concluded that better new or retrofit construction practices that include reinforcedconcrete shear walls may prove helpful in reducing risks in such seismic areas of Italy, other Mediterranean countries, and even in United States, where there are large inventories of deficient structures. ?? 2010, Earthquake Engineering Research Institute.

  10. Southern Peru desert shattered by the great 2001 earthquake: Implications for paleoseismic and paleo-El Niño–Southern Oscillation records

    OpenAIRE

    Keefer, David K.; Moseley, Michael E.

    2004-01-01

    In the desert region around the coastal city of Ilo, the great southern Peru earthquake of June 23, 2001 (8.2–8.4 moment magnitude), produced intense and widespread ground-failure effects. These effects included abundant landslides, pervasive ground cracking, microfracturing of surficial hillslope materials, collapse of drainage banks over long stretches, widening of hillside rills, and lengthening of first-order tributary channels. We have coined the term “shattered landscape” to describe th...

  11. Velocity characteristics of the earth crust in the Issyk-Kul'sk depresion as recorded from explosion and earthquake data

    Energy Technology Data Exchange (ETDEWEB)

    Moldobekov, K.; Sadybakasov, I.

    1979-01-01

    Results are given for studies of wave field change in the aforementioned region on the basis of earthquakes and explosions. Station anomalies are studied as well on the basis of experimental and theoretical studies. A velocity model of earth crust region is constructed from experimental hodographs, whose probability was found to be +-0.5 divided by +-1.0 second between the observed and computed gap time of total seismic waves. 5 references, 4 figures.

  12. Local amplification of seismic waves from the Denali earthquake and damaging seiches in Lake Union, Seattle, Washington

    Science.gov (United States)

    Barberopoulou, A.; Qamar, A.; Pratt, T.L.; Creager, K.C.; Steele, W.P.

    2004-01-01

    The Mw7.9 Denali, Alaska earthquake of 3 November, 2002, caused minor damage to at least 20 houseboats in Seattle, Washington by initiating water waves in Lake Union. These water waves were likely initiated during the large amplitude seismic surface waves from this earthquake. Maps of spectral amplification recorded during the Denali earthquake on the Pacific Northwest Seismic Network (PNSN) strong-motion instruments show substantially increased shear and surface wave amplitudes coincident with the Seattle sedimentary basin. Because Lake Union is situated on the Seattle basin, the size of the water waves may have been increased by local amplification of the seismic waves by the basin. Complete hazard assessments require understanding the causes of these water waves during future earthquakes. Copyright 2004 by the American Geophysical Union.

  13. Fault Rupture Model of the 2016 Gyeongju, South Korea, Earthquake and Its Implication for the Underground Fault System

    Science.gov (United States)

    Uchide, Takahiko; Song, Seok Goo

    2018-03-01

    The 2016 Gyeongju earthquake (ML 5.8) was the largest instrumentally recorded inland event in South Korea. It occurred in the southeast of the Korean Peninsula and was preceded by a large ML 5.1 foreshock. The aftershock seismicity data indicate that these earthquakes occurred on two closely collocated parallel faults that are oblique to the surface trace of the Yangsan fault. We investigate the rupture properties of these earthquakes using finite-fault slip inversion analyses. The obtained models indicate that the ruptures propagated NNE-ward and SSW-ward for the main shock and the large foreshock, respectively. This indicates that these earthquakes occurred on right-step faults and were initiated around a fault jog. The stress drops were up to 62 and 43 MPa for the main shock and the largest foreshock, respectively. These high stress drops imply high strength excess, which may be overcome by the stress concentration around the fault jog.

  14. Evaluation of the recorded ground motions for the unusual earthquake of 13 August 2006 ( M w 5.3) in Michoacán México

    Science.gov (United States)

    Ramírez-Gaytán, Alejandro; Jaimes, Miguel A.; Bandy, William L.; Huerfano, Victor M.; Salido-Ruiz, Ricardo A.

    2015-10-01

    The focal mechanism of the moderate earthquake of 13 August 2006 M w = 5.3, which occurred in the border coastal area between Michoacán and Colima, México, is unusual. As shown by the Global Centroid Moment Tensor (CMT) project and the Servicio Sismológico Nacional de Mexico (SSN), the thrust mechanism is striking almost perpendicularly to the majority of earthquakes occurring along the subduction zone of the Mexican Pacific continental margin which commonly strike nearly parallel to the trench. The purpose of this study is to analyze the observed ground motions of this particular event relative to those of the common events. First, we apply the H/V technique to verify that the stations involved in this study are nearly free of site effects. Then, we compare the observed ground motions with (i) three empirical ground motion prediction equations (GMPEs) appropriate for the region, (ii) ground motions of four real earthquakes with the common mechanism, and (iii) the Fourier spectrum of a selected common event.

  15. Source processes of strong earthquakes in the North Tien-Shan region

    Science.gov (United States)

    Kulikova, G.; Krueger, F.

    2013-12-01

    Tien-Shan region attracts attention of scientists worldwide due to its complexity and tectonic uniqueness. A series of very strong destructive earthquakes occurred in Tien-Shan at the turn of XIX and XX centuries. Such large intraplate earthquakes are rare in seismology, which increases the interest in the Tien-Shan region. The presented study focuses on the source processes of large earthquakes in Tien-Shan. The amount of seismic data is limited for those early times. In 1889, when a major earthquake has occurred in Tien-Shan, seismic instruments were installed in very few locations in the world and these analog records did not survive till nowadays. Although around a hundred seismic stations were operating at the beginning of XIX century worldwide, it is not always possible to get high quality analog seismograms. Digitizing seismograms is a very important step in the work with analog seismic records. While working with historical seismic records one has to take into account all the aspects and uncertainties of manual digitizing and the lack of accurate timing and instrument characteristics. In this study, we develop an easy-to-handle and fast digitization program on the basis of already existing software which allows to speed up digitizing process and to account for all the recoding system uncertainties. Owing to the lack of absolute timing for the historical earthquakes (due to the absence of a universal clock at that time), we used time differences between P and S phases to relocate the earthquakes in North Tien-Shan and the body-wave amplitudes to estimate their magnitudes. Combining our results with geological data, five earthquakes in North Tien-Shan were precisely relocated. The digitizing of records can introduce steps into the seismograms which makes restitution (removal of instrument response) undesirable. To avoid the restitution, we simulated historic seismograph recordings with given values for damping and free period of the respective instrument and

  16. Advancing Understanding of Earthquakes by Drilling an Eroding Convergent Margin

    Science.gov (United States)

    von Huene, R.; Vannucchi, P.; Ranero, C. R.

    2010-12-01

    A program of IODP with great societal relevance is sampling and instrumenting the seismogenic zone. The zone generates great earthquakes that trigger tsunamis, and submarine slides thereby endangering coastal communities containing over sixty percent of the earth’s population. To asses and mitigate this endangerment it is urgent to advance understanding of fault dynamics that allows more timely anticipation of hazardous seismicity. Seismogenesis on accreting and eroding convergent plate boundaries apparently differ because of dissimilar materials along the interplate fault. As the history of instrumentally recorded earthquakes expands the difference becomes clearer. The more homogeneous clay, silt and sand subducted at accreting margins is associated with great earthquakes (M 9) whereas the fragmented upper plate rock that can dominate subducted material along an eroding margin plate interface is associated with many tsunamigenic earthquakes (Bilek, 2010). Few areas have been identified where the seismogenic zone can be reached with scientific drilling. In IODP accreting margins are studied on the NanTroSeize drill transect off Japan where the ultimate drilling of the seismogenic interface may occur by the end of IODP. The eroding Costa Rica margin will be studied in CRISP where a drill program will begin in 2011. The Costa Rican geophysical site survey will be complete with acquisition and processing of 3D seismic data in 2011 but the entire drilling will not be accomplished in IODP. It is appropriate that the accreting margin study be accomplished soon considering the indications of a pending great earthquake that will affect a country that has devoted enormous resources to IODP. However, understanding the erosional end-member is scientifically as important to an understanding of fault mechanics. Transoceanic tsunamis affect the entire Pacific rim where most subduction zones are eroding margins. The Costa Rican subduction zone is less complex operationally and

  17. Solar UVR instrument inter-comparison focussing on measurement interval recording setting and solar zenith angle as important factors

    CSIR Research Space (South Africa)

    Wright, GY

    2015-09-01

    Full Text Available considerations, to make meaningful deductions from the data. By comparing two solar UVR instruments, namely, a UV biometer and a Davis Vantage Pro2 UVR Detector, we look at an important factor influencing ambient solar UVR, namely SZA, and its impact... Vantage Pro2 UV detector comprises a transducer which is a semiconductor photodiode with a spectral response that matches the McKinley/Diffey Erythemal Action Spectrum. It includes a diffuser which provides good cosine response and multiple hard...

  18. Connecting slow earthquakes to huge earthquakes

    OpenAIRE

    Obara, Kazushige; Kato, Aitaro

    2016-01-01

    Slow earthquakes are characterized by a wide spectrum of fault slip behaviors and seismic radiation patterns that differ from those of traditional earthquakes. However, slow earthquakes and huge megathrust earthquakes can have common slip mechanisms and are located in neighboring regions of the seismogenic zone. The frequent occurrence of slow earthquakes may help to reveal the physics underlying megathrust events as useful analogs. Slow earthquakes may function as stress meters because of th...

  19. What Can Sounds Tell Us About Earthquake Interactions?

    Science.gov (United States)

    Aiken, C.; Peng, Z.

    2012-12-01

    It is important not only for seismologists but also for educators to effectively convey information about earthquakes and the influences earthquakes can have on each other. Recent studies using auditory display [e.g. Kilb et al., 2012; Peng et al. 2012] have depicted catastrophic earthquakes and the effects large earthquakes can have on other parts of the world. Auditory display of earthquakes, which combines static images with time-compressed sound of recorded seismic data, is a new approach to disseminating information to a general audience about earthquakes and earthquake interactions. Earthquake interactions are influential to understanding the underlying physics of earthquakes and other seismic phenomena such as tremors in addition to their source characteristics (e.g. frequency contents, amplitudes). Earthquake interactions can include, for example, a large, shallow earthquake followed by increased seismicity around the mainshock rupture (i.e. aftershocks) or even a large earthquake triggering earthquakes or tremors several hundreds to thousands of kilometers away [Hill and Prejean, 2007; Peng and Gomberg, 2010]. We use standard tools like MATLAB, QuickTime Pro, and Python to produce animations that illustrate earthquake interactions. Our efforts are focused on producing animations that depict cross-section (side) views of tremors triggered along the San Andreas Fault by distant earthquakes, as well as map (bird's eye) views of mainshock-aftershock sequences such as the 2011/08/23 Mw5.8 Virginia earthquake sequence. These examples of earthquake interactions include sonifying earthquake and tremor catalogs as musical notes (e.g. piano keys) as well as audifying seismic data using time-compression. Our overall goal is to use auditory display to invigorate a general interest in earthquake seismology that leads to the understanding of how earthquakes occur, how earthquakes influence one another as well as tremors, and what the musical properties of these

  20. Research in historical earthquakes in the Korean peninsula and its circumferential regions

    Institute of Scientific and Technical Information of China (English)

    翟文杰; 吴戈; 韩绍欣

    2004-01-01

    @@ The historical earthquake data is one of the important foundations for seismic monitoring, earthquake fore-cast and seismic safety evaluation. However, the recognition of earthquake is limited by the scientific and techno-logical level. Therefore, the earthquake can only be described using perfect earthquake catalogue after the seismo-graph is invented. Before this time, the earthquake parameters were determined according to the earthquake disas-ter on the surface and the written records in history, and the earthquake level was measured using earthquake in-tensity.

  1. Understanding Great Earthquakes in Japan's Kanto Region

    Science.gov (United States)

    Kobayashi, Reiji; Curewitz, Daniel

    2008-10-01

    Third International Workshop on the Kanto Asperity Project; Chiba, Japan, 16-19 February 2008; The 1703 (Genroku) and 1923 (Taisho) earthquakes in Japan's Kanto region (M 8.2 and M 7.9, respectively) caused severe damage in the Tokyo metropolitan area. These great earthquakes occurred along the Sagami Trough, where the Philippine Sea slab is subducting beneath Japan. Historical records, paleoseismological research, and geophysical/geodetic monitoring in the region indicate that such great earthquakes will repeat in the future.

  2. Holocene deltaic succession recording millennium-scale subsidence trend near the source region of the 2011 Tohoku-oki earthquake: An example from the Tsugaruishi plain, northeast Japan

    Science.gov (United States)

    Niwa, Y.; Sugai, T.; Matsushima, Y.; Toda, S.

    2017-12-01

    For clarification of megathrust earthquake cycle with recurrence interval of several hundreds to about a thousand years, crustal movement trend on a timescale of 103-104 years can be basic and important data. Well-dated Holocene sedimentary succession provides useful information for estimation of crustal movement trend on a timescale of 103 - 104 years. Here we collected three sediment cores, TGI1, TGI2, and TGI3, from the Tsugaruishi delta plain on the central Sanriku coast, which is near the source region of the 2011 Tohoku-oki earthquake and where discrepancies in crustal movement have been reported between uplift on a timescale of 105 years inferred from marine terrace versus subsidence on a timescale of 101-102 years from geodetic measurement. We recognized a Holocene deltaic succession in all three cores; basal gravel of alluvium, floodplain sand and mud, inner bay mud, prodelta delta front sand and mud, and fluvial sand and gravel, from lower to upper. In core TGI3, from the farthest inland site, the intertidal sediment facies, deposited from 7500 to 7000 cal BP, and the overlying 6-m-thick delta to floodplain facies, deposited from 7000 to 5000 cal BP, are both below the present sea level. Because a sea-level highstand due to hydroisostatic uplift around Japan occurred in the mid-Holocene, we inferred that the Tsugaruishi plain subsided during the Holocene, and the estimated subsidence rate, 1.1-1.9 mm/yr at maximum, is consistent with the recently reported subsidence rate along the southern Sanriku coast. The results of this study confirm that the central to southern Sanriku coast is subsiding, in contrast to an interpretation based on the study of marine terraces that this part of the coast is uplifting. The Holocene deltaic succession presented here will be useful for constructing an earthquake cycle model related to plate subduction.

  3. Super instrumental El Niño events recorded by a Porites coral from the South China Sea

    Science.gov (United States)

    Wang, Xijie; Deng, Wenfeng; Liu, Xi; Wei, Gangjian; Chen, Xuefei; Zhao, Jian-xin; Cai, Guanqiang; Zeng, Ti

    2018-03-01

    The 2-7-year periodicities recorded in fossil coral records have been widely used to identify paleo-El Niño events. However, the reliability of this approach in the South China Sea (SCS) has not been assessed in detail. Therefore, this paper presents monthly resolution geochemical records covering the period 1978-2015 obtained from a Porites coral recovered from the SCS to test the reliability of this method. The results suggest that the SCS coral reliably recorded local seawater conditions and the super El Niño events that occurred over the past 3 decades, but does not appear to have been sensitive enough to record all the other El Niños. In detail, the Sr/Ca series distinctly documents only the two super El Niños of 1997-1998 and 2014-2016 as obvious low values, but does not match the Oceanic Niño Index well. The super El Niño of 1982-1983 was identified by the growth hiatus caused by the coral bleaching and subsequent death of the coral. Three distinct stepwise variations occur in the δ13C series that are coincident with the three super El Niños, which may be related to a substantial decline in endosymbiotic zooxanthellae density caused by the increase in temperature during an El Niño or the selective utilization of different zooxanthellaes that was required to survive in the extreme environment. The increase in rainfall and temperatures over the SCS during El Niños counteracts the effects on seawater δ18O (δ18Osw) and salinity; consequently, coral Δδ18O series can be used as a proxy for δ18Osw and salinity, but are not appropriate for identifying El Niño activity. The findings presented here suggest that the method to identify paleo-El Niño activity based on the 2-7-year periodicities preserved in the SCS coral records might not be reliable, because the SCS is on the edge of El Niño anomalies due to its great distance from the central equatorial Pacific and the imprints of weak and medium strength El Niño events may not be recorded by the

  4. a Circleless "2D/3D Total STATION": a Low Cost Instrument for Surveying, Recording Point Clouds, Documentation, Image Acquisition and Visualisation

    Science.gov (United States)

    Scherer, M.

    2013-07-01

    Hardware and software of the universally applicable instrument - referred to as a 2D/3D total station - are described here, as well as its practical use. At its core it consists of a 3D camera - often also called a ToF camera, a pmd camera or a RIM-camera - combined with a common industrial 2D camera. The cameras are rigidly coupled with their optical axes in parallel. A new type of instrument was created mounting this 2D/3D system on a tripod in a specific way. Because of it sharing certain characteristics with a total station and a tacheometer, respectively, the new device was called a 2D/3D total station. It may effectively replace a common total station or a laser scanner in some respects. After a brief overview of the prototype's features this paper then focuses on the methodological characteristics for practical application. Its usability as a universally applicable stand-alone instrument is demonstrated for surveying, recording RGB-coloured point clouds as well as delivering images for documentation and visualisation. Because of its limited range (10m without reflector and 150 m to reflector prisms) and low range accuracy (ca. 2 cm to 3 cm) compared to present-day total stations and laser scanners, the practical usage of the 2D/3D total station is currently limited to acquisition of accidents, forensic purpuses, speleology or facility management, as well as architectural recordings with low requirements regarding accuracy. However, the author is convinced that in the near future advancements in 3D camera technology will allow this type of comparatively low cost instrument to replace the total station as well as the laser scanner in an increasing number of areas.

  5. EARTHQUAKE-INDUCED DEFORMATION STRUCTURES AND RELATED TO EARTHQUAKE MAGNITUDES

    Directory of Open Access Journals (Sweden)

    Savaş TOPAL

    2003-02-01

    Full Text Available Earthquake-induced deformation structures which are called seismites may helpful to clasify the paleoseismic history of a location and to estimate the magnitudes of the potention earthquakes in the future. In this paper, seismites were investigated according to the types formed in deep and shallow lake sediments. Seismites are observed forms of sand dikes, introduced and fractured gravels and pillow structures in shallow lakes and pseudonodules, mushroom-like silts protruding laminites, mixed layers, disturbed varved lamination and loop bedding in deep lake sediments. Earthquake-induced deformation structures, by benefiting from previous studies, were ordered according to their formations and earthquake magnitudes. In this order, the lowest eartquake's record is loop bedding and the highest one is introduced and fractured gravels in lacustrine deposits.

  6. Geotechnical aspects of the 2016 MW 6.2, MW 6.0, and MW 7.0 Kumamoto earthquakes

    Science.gov (United States)

    Kayen, Robert E.; Dashti, Shideh; Kokusho, T.; Hazarika, H.; Franke, Kevin; Oettle, N. K.; Wham, Brad; Ramirez Calderon, Jenny; Briggs, Dallin; Guillies, Samantha; Cheng, Katherine; Tanoue, Yutaka; Takematsu, Katsuji; Matsumoto, Daisuke; Morinaga, Takayuki; Furuichi, Hideo; Kitano, Yuuta; Tajiri, Masanori; Chaudhary, Babloo; Nishimura, Kengo; Chu, Chu

    2017-01-01

    The 2016 Kumamoto earthquakes are a series of events that began with an earthquake of moment magnitude 6.2 on the Hinagu Fault on April 14, 2016, followed by another foreshock of moment magnitude 6.0 on the Hinagu Fault on April 15, 2016, and a larger moment magnitude 7.0 event on the Futagawa Fault on April 16, 2016 beneath Kumamoto City, Kumamoto Prefecture on Kyushu, Japan. These events are the strongest earthquakes recorded in Kyushu during the modern instrumental era. The earthquakes resulted in substantial damage to infrastructure, buildings, cultural heritage of Kumamoto Castle, roads and highways, slopes, and river embankments due to earthquake-induced landsliding and debris flows. Surface fault rupture produced offset and damage to roads, buildings, river levees, and an agricultural dam. Surprisingly, given the extremely intense earthquake motions, liquefaction occurred only in a few districts of Kumamoto City and in the port areas indicating that the volcanic soils were less susceptible to liquefying than expected given the intensity of earthquake shaking, a significant finding from this event.

  7. The Alaska earthquake, March 27, 1964: lessons and conclusions

    Science.gov (United States)

    Eckel, Edwin B.

    1970-01-01

    One of the greatest earthquakes of all time struck south-central Alaska on March 27, 1964. Strong motion lasted longer than for most recorded earthquakes, and more land surface was dislocated, vertically and horizontally, than by any known previous temblor. Never before were so many effects on earth processes and on the works of man available for study by scientists and engineers over so great an area. The seismic vibrations, which directly or indirectly caused most of the damage, were but surface manifestations of a great geologic event-the dislocation of a huge segment of the crust along a deeply buried fault whose nature and even exact location are still subjects for speculation. Not only was the land surface tilted by the great tectonic event beneath it, with resultant seismic sea waves that traversed the entire Pacific, but an enormous mass of land and sea floor moved several tens of feet horizontally toward the Gulf of Alaska. Downslope mass movements of rock, earth, and snow were initiated. Subaqueous slides along lake shores and seacoasts, near-horizontal movements of mobilized soil (“landspreading”), and giant translatory slides in sensitive clay did the most damage and provided the most new knowledge as to the origin, mechanics, and possible means of control or avoidance of such movements. The slopes of most of the deltas that slid in 1964, and that produced destructive local waves, are still as steep or steeper than they were before the earthquake and hence would be unstable or metastable in the event of another great earthquake. Rockslide avalanches provided new evidence that such masses may travel on cushions of compressed air, but a widely held theory that glaciers surge after an earthquake has not been substantiated. Innumerable ground fissures, many of them marked by copious emissions of water, caused much damage in towns and along transportation routes. Vibration also consolidated loose granular materials. In some coastal areas, local

  8. Leveraging geodetic data to reduce losses from earthquakes

    Science.gov (United States)

    Murray, Jessica R.; Roeloffs, Evelyn A.; Brooks, Benjamin A.; Langbein, John O.; Leith, William S.; Minson, Sarah E.; Svarc, Jerry L.; Thatcher, Wayne R.

    2018-04-23

    event response products and by expanded use of geodetic imaging data to assess fault rupture and source parameters.Uncertainties in the NSHM, and in regional earthquake models, are reduced by fully incorporating geodetic data into earthquake probability calculations.Geodetic networks and data are integrated into the operations and earthquake information products of the Advanced National Seismic System (ANSS).Earthquake early warnings are improved by more rapidly assessing ground displacement and the dynamic faulting process for the largest earthquakes using real-time geodetic data.Methodology for probabilistic earthquake forecasting is refined by including geodetic data when calculating evolving moment release during aftershock sequences and by better understanding the implications of transient deformation for earthquake likelihood.A geodesy program that encompasses a balanced mix of activities to sustain missioncritical capabilities, grows new competencies through the continuum of fundamental to applied research, and ensures sufficient resources for these endeavors provides a foundation by which the EHP can be a leader in the application of geodesy to earthquake science. With this in mind the following objectives provide a framework to guide EHP efforts:Fully utilize geodetic information to improve key products, such as the NSHM and EEW, and to address new ventures like the USGS Subduction Zone Science Plan.Expand the variety, accuracy, and timeliness of post-earthquake information products, such as PAGER (Prompt Assessment of Global Earthquakes for Response), through incorporation of geodetic observations.Determine if geodetic measurements of transient deformation can significantly improve estimates of earthquake probability.Maintain an observational strategy aligned with the target outcomes of this document that includes continuous monitoring, recording of ephemeral observations, focused data collection for use in research, and application-driven data processing and

  9. The NetQuakes Project - Research-quality Seismic Data Transmitted via the Internet from Citizen-hosted Instruments (Invited)

    Science.gov (United States)

    Luetgert, J. H.; Oppenheimer, D. H.; Hamilton, J.

    2010-12-01

    The USGS seeks accelerograph spacing of 5-10 km in selected urban areas of the US to obtain spatially un-aliased recordings of strong ground motions during large earthquakes. These dense measurements will improve our ability to make rapid post-earthquake assessments of expected damage and contribute to the continuing development of engineering standards for construction. To achieve this goal the USGS and its university partners are deploying “NetQuakes” seismographs, designed to record moderate to large earthquakes from the near field to about 100 km. The instruments have tri-axial Colibrys 2005SF MEMS sensors, clip at 3g, and have 18-bit resolution. These instruments are uniquely designed for deployment in private homes, businesses, public buildings and schools where there is an existing Broadband connection to the Internet. The NetQuakes instruments connect to a local network using WiFi and then via the Internet to USGS servers to a) upload triggered accelerograms in miniSEED format, P arrival times, and computed peak ground motion parameters immediately after an earthquake; b) download software updates; c) respond to requests for log files, execute UNIX scripts, and upload waveforms from long-term memory for quakes with peak motions below the trigger threshold; d) send state-of-health (SOH) information in XML format every 10 minutes; and e) synchronize instrument clocks to 1ms accuracy using the Network Time Protocol. NetQuakes instruments cost little to operate and save about $600/yr/site compared to instruments that transmit data via leased telemetry. After learning about the project through press releases, thousands of citizens have registered to host an instrument at http://earthquake.usgs.gov/netquakes using a Google Map interface that depicts where we seek instrument sites. The website also provides NetQuakes hosts access to waveform images recorded by instruments installed in their building. Since 3/2009, the NetQuakes project has installed over 100

  10. Southern Peru desert shattered by the great 2001 earthquake: Implications for paleoseismic and paleo-El Niño–Southern Oscillation records

    Science.gov (United States)

    Keefer, David K.; Moseley, Michael E.

    2004-01-01

    In the desert region around the coastal city of Ilo, the great southern Peru earthquake of June 23, 2001 (8.2–8.4 moment magnitude), produced intense and widespread ground-failure effects. These effects included abundant landslides, pervasive ground cracking, microfracturing of surficial hillslope materials, collapse of drainage banks over long stretches, widening of hillside rills, and lengthening of first-order tributary channels. We have coined the term “shattered landscape” to describe the severity of these effects. Long-term consequences of this landscape shattering are inferred to include increased runoff and sediment transport during postearthquake rainstorms. This inference was confirmed during the first minor postearthquake rainstorm there, which occurred in June and July of 2002. Greater amounts of rainfall in this desert region have historically been associated with El Niño events. Previous studies of an unusual paleoflood deposit in this region have concluded that it is the product of El Niño-generated precipitation falling on seismically disturbed landscapes. The effects of the 2001 earthquake and 2002 rainstorm support that conclusion. PMID:15263069

  11. Southern Peru desert shattered by the great 2001 earthquake: implications for paleoseismic and paleo-El Nino-Southern Oscillation records.

    Science.gov (United States)

    Keefer, David K; Moseley, Michael E

    2004-07-27

    In the desert region around the coastal city of Ilo, the great southern Peru earthquake of June 23, 2001 (8.2-8.4 moment magnitude), produced intense and widespread ground-failure effects. These effects included abundant landslides, pervasive ground cracking, microfracturing of surficial hillslope materials, collapse of drainage banks over long stretches, widening of hillside rills, and lengthening of first-order tributary channels. We have coined the term "shattered landscape" to describe the severity of these effects. Long-term consequences of this landscape shattering are inferred to include increased runoff and sediment transport during postearthquake rainstorms. This inference was confirmed during the first minor postearthquake rainstorm there, which occurred in June and July of 2002. Greater amounts of rainfall in this desert region have historically been associated with El Niño events. Previous studies of an unusual paleoflood deposit in this region have concluded that it is the product of El Niño-generated precipitation falling on seismically disturbed landscapes. The effects of the 2001 earthquake and 2002 rainstorm support that conclusion.

  12. The NUADU experiment on TC-2 and the first Energetic Neutral Atom (ENA images recorded by this instrument

    Directory of Open Access Journals (Sweden)

    S. McKenna-Lawlor

    2005-11-01

    Full Text Available The Earth’s ring current and how it responds to varying interplanetary conditions is described and an account provided of the production of Energetic Neutral Atoms (ENAs in the geo-corona. Also, the potential to remotely monitor, on a global scale, the temporal and spatial evolution of magnetospheric plasma populations through analysing ENA images recorded during magnetic storms/substorms is indicated. A technical account of the Energetic NeUtral Atom Detector Unit NUADU aboard China’s TC-2 mission (measurement range 45–>158 keV follows, together with an account of the scientific objectives of NUADU, both in stand-alone mode and in the context of multi-point imaging. Low altitude ENA emissions recorded by NUADU during south polar passages of TC-2 at the time of a moderate magnetic storm in September 2004, as well as bright ring current emissions recorded in November 2004 during a major geomagnetic storm, are presented and discussed in the context of various, accompanying, terrestrial disturbances. Also, ENA observations of the November 2004 ring current imaged simultaneously by TC-2/NUADU and by IMAGE/ HENA (viewing, respectively, from the Northern and Southern Hemispheres, are compared.

  13. Long-term perspectives on giant earthquakes and tsunamis at subduction zones

    Science.gov (United States)

    Satake, K.; Atwater, B.F.; ,

    2007-01-01

    Histories of earthquakes and tsunamis, inferred from geological evidence, aid in anticipating future catastrophes. This natural warning system now influences building codes and tsunami planning in the United States, Canada, and Japan, particularly where geology demonstrates the past occurrence of earthquakes and tsunamis larger than those known from written and instrumental records. Under favorable circumstances, paleoseismology can thus provide long-term advisories of unusually large tsunamis. The extraordinary Indian Ocean tsunami of 2004 resulted from a fault rupture more than 1000 km in length that included and dwarfed fault patches that had broken historically during lesser shocks. Such variation in rupture mode, known from written history at a few subduction zones, is also characteristic of earthquake histories inferred from geology on the Pacific Rim. Copyright ?? 2007 by Annual Reviews. All rights reserved.

  14. [Web-based electronic patient record as an instrument for quality assurance within an integrated care concept].

    Science.gov (United States)

    Händel, A; Jünemann, A G M; Prokosch, H-U; Beyer, A; Ganslandt, T; Grolik, R; Klein, A; Mrosek, A; Michelson, G; Kruse, F E

    2009-03-01

    A prerequisite for integrated care programmes is the implementation of a communication network meeting quality assurance standards. Against this background the main objective of the integrated care project between the University Eye Hospital Erlangen and the health insurance company AOK Bayern was to evaluate the potential and the acceptance of a web-based electronic patient record in the context of cataract and retinal surgery. Standardised modules for capturing pre-, intra- and post-operative data on the basis of clinical pathway guidelines for cataract- and retinal surgery have been developed. There are 6 data sets recorded per patient (1 pre-operative, 1 operative, 4-6 post-operative). For data collection, a web-based communication system (Soarian Integrated Care) has been chosen which meets the high requirements in data security, as well as being easy to handle. This teleconsultation system and the embedded electronic patient record are independent of the software used by respective offices and hospitals. Data transmission and storage were carried out in real-time. At present, 101 private ophthalmologists are taking part in the IGV contract with the University Eye Hospital Erlangen. This corresponds to 52% of all private ophthalmologists in the region. During the period from January 1st 2006 to December 31st 2006, 1844 patients were entered. Complete documentation was achieved in 1390 (75%) of all surgical procedures. For evaluation of this data, a multidimensional report and analysis tool (Cognos) was used. The deviation from target refraction as one quality indicator was in the mean 0.09 diopter. The web-based patient record used in this project was highly accepted by the private ophthalmologists. However there are still general concerns against the exchange of medical data via the internet. Nevertheless, the web-based patient record is an essential tool for a functional integration between the ambulatory and stationary health-care units. In addition to the

  15. A 'new generation' earthquake catalogue

    Directory of Open Access Journals (Sweden)

    E. Boschi

    2000-06-01

    Full Text Available In 1995, we published the first release of the Catalogo dei Forti Terremoti in Italia, 461 a.C. - 1980, in Italian (Boschi et al., 1995. Two years later this was followed by a second release, again in Italian, that included more earthquakes, more accurate research and a longer time span (461 B.C. to 1990 (Boschi et al., 1997. Aware that the record of Italian historical seismicity is probably the most extensive of the whole world, and hence that our catalogue could be of interest for a wider interna-tional readership, Italian was clearly not the appropriate language to share this experience with colleagues from foreign countries. Three years after publication of the second release therefore, and after much additional research and fine tuning of methodologies and algorithms, I am proud to introduce this third release in English. All the tools and accessories have been translated along with the texts describing the development of the underlying research strategies and current contents. The English title is Catalogue of Strong Italian Earthquakes, 461 B.C. to 1997. This Preface briefly describes the scientific context within which the Catalogue of Strong Italian Earthquakes was conceived and progressively developed. The catalogue is perhaps the most impor-tant outcome of a well-established joint project between the Istituto Nazionale di Geofisica, the leading Italian institute for basic and applied research in seismology and solid earth geophysics, and SGA (Storia Geofisica Ambiente, a private firm specialising in the historical investigation and systematisation of natural phenomena. In her contribution "Method of investigation, typology and taxonomy of the basic data: navigating between seismic effects and historical contexts", Emanuela Guidoboni outlines the general framework of modern historical seismology, its complex relation with instrumental seismology on the one hand and historical research on the other. This presentation also highlights

  16. The Development of Several Electromagnetic Monitoring Strategies and Algorithms for Validating Pre-Earthquake Electromagnetic Signals

    Science.gov (United States)

    Bleier, T. E.; Dunson, J. C.; Roth, S.; Mueller, S.; Lindholm, C.; Heraud, J. A.

    2012-12-01

    QuakeFinder, a private research group in California, reports on the development of a 100+ station network consisting of 3-axis induction magnetometers, and air conductivity sensors to collect and characterize pre-seismic electromagnetic (EM) signals. These signals are combined with daily Infra Red signals collected from the GOES weather satellite infrared (IR) instrument to compare and correlate with the ground EM signals, both from actual earthquakes and boulder stressing experiments. This presentation describes the efforts QuakeFinder has undertaken to automatically detect these pulse patterns using their historical data as a reference, and to develop other discriminative algorithms that can be used with air conductivity sensors, and IR instruments from the GOES satellites. The overall big picture results of the QuakeFinder experiment are presented. In 2007, QuakeFinder discovered the occurrence of strong uni-polar pulses in their magnetometer coil data that increased in tempo dramatically prior to the M5.1 earthquake at Alum Rock, California. Suggestions that these pulses might have been lightning or power-line arcing did not fit with the data actually recorded as was reported in Bleier [2009]. Then a second earthquake occurred near the same site on January 7, 2010 as was reported in Dunson [2011], and the pattern of pulse count increases before the earthquake occurred similarly to the 2007 event. There were fewer pulses, and the magnitude of them was decreased, both consistent with the fact that the earthquake was smaller (M4.0 vs M5.4) and farther away (7Km vs 2km). At the same time similar effects were observed at the QuakeFinder Tacna, Peru site before the May 5th, 2010 M6.2 earthquake and a cluster of several M4-5 earthquakes.

  17. Using Smartphones to Detect Earthquakes

    Science.gov (United States)

    Kong, Q.; Allen, R. M.

    2012-12-01

    We are using the accelerometers in smartphones to record earthquakes. In the future, these smartphones may work as a supplement network to the current traditional network for scientific research and real-time applications. Given the potential number of smartphones, and small separation of sensors, this new type of seismic dataset has significant potential provides that the signal can be separated from the noise. We developed an application for android phones to record the acceleration in real time. These records can be saved on the local phone or transmitted back to a server in real time. The accelerometers in the phones were evaluated by comparing performance with a high quality accelerometer while located on controlled shake tables for a variety of tests. The results show that the accelerometer in the smartphone can reproduce the characteristic of the shaking very well, even the phone left freely on the shake table. The nature of these datasets is also quite different from traditional networks due to the fact that smartphones are moving around with their owners. Therefore, we must distinguish earthquake signals from other daily use. In addition to the shake table tests that accumulated earthquake records, we also recorded different human activities such as running, walking, driving etc. An artificial neural network based approach was developed to distinguish these different records. It shows a 99.7% successful rate of distinguishing earthquakes from the other typical human activities in our database. We are now at the stage ready to develop the basic infrastructure for a smartphone seismic network.

  18. Twitter earthquake detection: Earthquake monitoring in a social world

    Science.gov (United States)

    Earle, Paul S.; Bowden, Daniel C.; Guy, Michelle R.

    2011-01-01

    The U.S. Geological Survey (USGS) is investigating how the social networking site Twitter, a popular service for sending and receiving short, public text messages, can augment USGS earthquake response products and the delivery of hazard information. Rapid detection and qualitative assessment of shaking events are possible because people begin sending public Twitter messages (tweets) with in tens of seconds after feeling shaking. Here we present and evaluate an earthquake detection procedure that relies solely on Twitter data. A tweet-frequency time series constructed from tweets containing the word "earthquake" clearly shows large peaks correlated with the origin times of widely felt events. To identify possible earthquakes, we use a short-term-average, long-term-average algorithm. When tuned to a moderate sensitivity, the detector finds 48 globally-distributed earthquakes with only two false triggers in five months of data. The number of detections is small compared to the 5,175 earthquakes in the USGS global earthquake catalog for the same five-month time period, and no accurate location or magnitude can be assigned based on tweet data alone. However, Twitter earthquake detections are not without merit. The detections are generally caused by widely felt events that are of more immediate interest than those with no human impact. The detections are also fast; about 75% occur within two minutes of the origin time. This is considerably faster than seismographic detections in poorly instrumented regions of the world. The tweets triggering the detections also provided very short first-impression narratives from people who experienced the shaking.

  19. Simulated earthquake ground motions

    International Nuclear Information System (INIS)

    Vanmarcke, E.H.; Gasparini, D.A.

    1977-01-01

    The paper reviews current methods for generating synthetic earthquake ground motions. Emphasis is on the special requirements demanded of procedures to generate motions for use in nuclear power plant seismic response analysis. Specifically, very close agreement is usually sought between the response spectra of the simulated motions and prescribed, smooth design response spectra. The features and capabilities of the computer program SIMQKE, which has been widely used in power plant seismic work are described. Problems and pitfalls associated with the use of synthetic ground motions in seismic safety assessment are also pointed out. The limitations and paucity of recorded accelerograms together with the widespread use of time-history dynamic analysis for obtaining structural and secondary systems' response have motivated the development of earthquake simulation capabilities. A common model for synthesizing earthquakes is that of superposing sinusoidal components with random phase angles. The input parameters for such a model are, then, the amplitudes and phase angles of the contributing sinusoids as well as the characteristics of the variation of motion intensity with time, especially the duration of the motion. The amplitudes are determined from estimates of the Fourier spectrum or the spectral density function of the ground motion. These amplitudes may be assumed to be varying in time or constant for the duration of the earthquake. In the nuclear industry, the common procedure is to specify a set of smooth response spectra for use in aseismic design. This development and the need for time histories have generated much practical interest in synthesizing earthquakes whose response spectra 'match', or are compatible with a set of specified smooth response spectra

  20. Iterative inversion of global magnetospheric ion distributions using energetic neutral atom (ENA images recorded by the NUADU/TC2 instrument

    Directory of Open Access Journals (Sweden)

    L. Lu

    2008-06-01

    Full Text Available A method has been developed for extracting magnetospheric ion distributions from Energetic Neutral Atom (ENA measurements made by the NUADU instrument on the TC-2 spacecraft. Based on a constrained linear inversion, this iterative technique is suitable for use in the case of an ENA image measurement, featuring a sharply peaked spatial distribution. The method allows for magnetospheric ion distributions to be extracted from a low-count ENA image recorded over a short integration time (5 min. The technique is demonstrated through its application to a set of representative ENA images recorded in energy Channel~2 (hydrogen: 50–81 keV, oxygen: 138–185 keV of the NUADU instrument during a geomagnetic storm. It is demonstrated that this inversion method provides a useful tool for extracting ion distribution information from ENA data that are characterized by high temporal and spatial resolution. The recovered ENA images obtained from inverted ion fluxes match most effectively the measurements made at maximum ENA intensity.

  1. Impact of the ozone monitoring instrument row anomaly on the long-term record of aerosol products

    Science.gov (United States)

    Torres, Omar; Bhartia, Pawan K.; Jethva, Hiren; Ahn, Changwoo

    2018-05-01

    Since about three years after the launch the Ozone Monitoring Instrument (OMI) on the EOS-Aura satellite, the sensor's viewing capability has been affected by what is believed to be an internal obstruction that has reduced OMI's spatial coverage. It currently affects about half of the instrument's 60 viewing positions. In this work we carry out an analysis to assess the effect of the reduced spatial coverage on the monthly average values of retrieved aerosol optical depth (AOD), single scattering albedo (SSA) and the UV Aerosol Index (UVAI) using the 2005-2007 three-year period prior to the onset of the row anomaly. Regional monthly average values calculated using viewing positions 1 through 30 were compared to similarly obtained values using positions 31 through 60, with the expectation of finding close agreement between the two calculations. As expected, mean monthly values of AOD and SSA obtained with these two scattering-angle dependent subsets of OMI observations agreed over regions where carbonaceous or sulphate aerosol particles are the predominant aerosol type. However, over arid regions, where desert dust is the main aerosol type, significant differences between the two sets of calculated regional mean values of AOD were observed. As it turned out, the difference in retrieved desert dust AOD between the scattering-angle dependent observation subsets was due to the incorrect representation of desert dust scattering phase function. A sensitivity analysis using radiative transfer calculations demonstrated that the source of the observed AOD bias was the spherical shape assumption of desert dust particles. A similar analysis in terms of UVAI yielded large differences in the monthly mean values for the two sets of calculations over cloudy regions. On the contrary, in arid regions with minimum cloud presence, the resulting UVAI monthly average values for the two sets of observations were in very close agreement. The discrepancy under cloudy conditions was found

  2. Soil structure interactions of eastern U.S. type earthquakes

    International Nuclear Information System (INIS)

    Chang Chen; Serhan, S.

    1991-01-01

    Two types of earthquakes have occurred in the eastern US in the past. One of them was the infrequent major events such as the 1811-1812 New Madrid Earthquakes, or the 1886 Charleston Earthquake. The other type was the frequent shallow earthquakes with high frequency, short duration and high accelerations. Two eastern US nuclear power plants, V.C Summer and Perry, went through extensive licensing effort to obtain fuel load licenses after this type of earthquake was recorded on sites and exceeded the design bases beyond 10 hertz region. This paper discusses the soil-structure interactions of the latter type of earthquakes

  3. Source complexity and the physical mechanism of the 2015 Mw 7.9 Bonin Island earthquake

    Science.gov (United States)

    Chen, Y.; Meng, L.; Wen, L.

    2015-12-01

    The 30 May 2015 Mw 7.9 Bonin Island earthquake is the largest instrument-recorded deep-focus earthquake in the Izu-Bonin arc. It occurred approximately 100 km deeper than the previous seismicity, in the region unlikely to be within the core of the subducting Izu-Bonin slab. The earthquake provides an unprecedented opportunity to understand the unexpected occurrence of such isolated deep earthquakes. Multiple source inversion of the P, SH, pP and sSH phases and a novel fully three-dimensional back-projection of P and pP phases are applied to study the coseismic source process. The subevents locations and short-period energy radiations both show a L-shape bilateral rupture propagating initially in the SW direction then in the NW direction with an average rupture speed of 2.0 km/s. The decrease of focal depth on the NW branch suggests that the rupture is consistent with a single sub-horizontal plane inferred from the GCMT solution. The multiple source inversion further indicates slight variation of the focal strikes of the sub-events with the curvature of the subducting Izu-Bonin slab. The rupture is confined within an area of 20 km x 35 km, rather compact compared with the shallow earthquake of similar magnitude. The earthquake is of high stress drop on the order of 100 MPa and a low seismic efficiency of 0.19, indicating large frictional heat dissipation. The only aftershock is 11 km to the east of the mainshock hypocenter and 3 km away from the centroid of the first sub-event. Analysis of the regional tomography and nearby seismicity suggests that the earthquake may occur at the edge/periphery of the bending slab and is unlikely to be within the "cold" metastable olivine wedge. Our results suggest the spontaneous nucleation of the thermally induced shear instability is a possible mechanism for such isolated deep earthquakes.

  4. Retrospective analysis of the Spitak earthquake

    Directory of Open Access Journals (Sweden)

    A. K. Tovmassian

    1995-06-01

    Full Text Available Based on the retrospective analysis of numerous data and studies of the Spitak earthquake the present work at- tempts to shed light on different aspects of that catastrophic seismic event which occurred in Northern Arme- nia on December 7, 1988. The authors follow a chronological order of presentation, namely: changes in geo- sphere, atmosphere, biosphere during the preparation of the Spitak earthquake, foreshocks, main shock, after- shocks, focal mechanisms, historical seismicity; seismotectonic position of the source, strong motion records, site effects; the macroseismic effect, collapse of buildings and structures; rescue activities; earthquake conse- quences; and the lessons of the Spitak earthquake.

  5. SEISMIC BEHAVIOR OF THE TOKYO BAY AREA DURING THE 2011 OFF THE PACIFIC COAST OF TOHOKU EARTHQUAKE USING DOWNHOLE ARRAY RECORDS

    Science.gov (United States)

    Ikeda, Takaaki; Konagai, Kazuo; Katagiri, Toshihiko

    Underground motions within a hard diluvial stratum were obtained in the March 11th 2011 Great East Japan Earthquake at a downhole in the Tokyo Bay area, which has suffered serious sand-liquefaction over its long 42km2 stretch. The motions in the diluvial sand deposit are characterized by their (1) long dura-tion times with 6 to 8s components surpassing others, (2) moderate amplitude of 51.1 cm/s2 in PGA, which is estimated to have resulted in moderate average strains of 8 to 9 × 10-4 and 5 to 7 × 10-4 over shal-low -2 to -30m and deep -30 to -77m soil deposits, respectively. The peak strain reached in the interior of soil was estimated to be about 1.3 × 10-3.

  6. Application of Hilbert-Huang Transform in Generating Spectrum-Compatible Earthquake Time Histories

    OpenAIRE

    Ni, Shun-Hao; Xie, Wei-Chau; Pandey, Mahesh

    2011-01-01

    Spectrum-compatible earthquake time histories have been widely used for seismic analysis and design. In this paper, a data processing method, Hilbert-Huang transform, is applied to generate earthquake time histories compatible with the target seismic design spectra based on multiple actual earthquake records. Each actual earthquake record is decomposed into several components of time-dependent amplitude and frequency by Hilbert-Huang transform. The spectrum-compatible earthquake time history ...

  7. Satellite Infrared Radiation Measurements Prior to the Major Earthquakes

    Science.gov (United States)

    Ouzounov, Dimitar; Pulintes, S.; Bryant, N.; Taylor, Patrick; Freund, F.

    2005-01-01

    This work describes our search for a relationship between tectonic stresses and increases in mid-infrared (IR) flux as part of a possible ensemble of electromagnetic (EM) phenomena that may be related to earthquake activity. We present and &scuss observed variations in thermal transients and radiation fields prior to the earthquakes of Jan 22, 2003 Colima (M6.7) Mexico, Sept. 28 .2004 near Parkfield (M6.0) in California and Northern Sumatra (M8.5) Dec. 26,2004. Previous analysis of earthquake events has indicated the presence of an IR anomaly, where temperatures increased or did not return to its usual nighttime value. Our procedures analyze nighttime satellite data that records the general condtion of the ground after sunset. We have found from the MODIS instrument data that five days before the Colima earthquake the IR land surface nighttime temperature rose up to +4 degrees C in a 100 km radius around the epicenter. The IR transient field recorded by MODIS in the vicinity of Parkfield, also with a cloud free environment, was around +1 degree C and is significantly smaller than the IR anomaly around the Colima epicenter. Ground surface temperatures near the Parkfield epicenter four days prior to the earthquake show steady increase. However, on the night preceding the quake, a significant drop in relative humidity was indicated, process similar to those register prior to the Colima event. Recent analyses of continuous ongoing long- wavelength Earth radiation (OLR) indicate significant and anomalous variability prior to some earthquakes. The cause of these anomalies is not well understood but could be the result of a triggering by an interaction between the lithosphere-hydrosphere and atmospheric related to changes in the near surface electrical field and/or gas composition prior to the earthquake. The OLR anomaly usually covers large areas surrounding the main epicenter. We have found strong anomalies signal (two sigma) along the epicentral area signals on Dec 21

  8. Probable Maximum Earthquake Magnitudes for the Cascadia Subduction

    Science.gov (United States)

    Rong, Y.; Jackson, D. D.; Magistrale, H.; Goldfinger, C.

    2013-12-01

    The concept of maximum earthquake magnitude (mx) is widely used in seismic hazard and risk analysis. However, absolute mx lacks a precise definition and cannot be determined from a finite earthquake history. The surprising magnitudes of the 2004 Sumatra and the 2011 Tohoku earthquakes showed that most methods for estimating mx underestimate the true maximum if it exists. Thus, we introduced the alternate concept of mp(T), probable maximum magnitude within a time interval T. The mp(T) can be solved using theoretical magnitude-frequency distributions such as Tapered Gutenberg-Richter (TGR) distribution. The two TGR parameters, β-value (which equals 2/3 b-value in the GR distribution) and corner magnitude (mc), can be obtained by applying maximum likelihood method to earthquake catalogs with additional constraint from tectonic moment rate. Here, we integrate the paleoseismic data in the Cascadia subduction zone to estimate mp. The Cascadia subduction zone has been seismically quiescent since at least 1900. Fortunately, turbidite studies have unearthed a 10,000 year record of great earthquakes along the subduction zone. We thoroughly investigate the earthquake magnitude-frequency distribution of the region by combining instrumental and paleoseismic data, and using the tectonic moment rate information. To use the paleoseismic data, we first estimate event magnitudes, which we achieve by using the time interval between events, rupture extent of the events, and turbidite thickness. We estimate three sets of TGR parameters: for the first two sets, we consider a geographically large Cascadia region that includes the subduction zone, and the Explorer, Juan de Fuca, and Gorda plates; for the third set, we consider a narrow geographic region straddling the subduction zone. In the first set, the β-value is derived using the GCMT catalog. In the second and third sets, the β-value is derived using both the GCMT and paleoseismic data. Next, we calculate the corresponding mc

  9. Foreshocks and aftershocks locations of the 2014 Pisagua, N. Chile earthquake: history of a megathrust earthquake nucleation

    Science.gov (United States)

    Fuenzalida Velasco, Amaya; Rietbrock, Andreas; Tavera, Hernando; Ryder, Isabelle; Ruiz, Sergio; Thomas, Reece; De Angelis, Silvio; Bondoux, Francis

    2015-04-01

    The April 2014 Mw 8.1 Pisagua earthquake occurred in the Northern Chile seismic gap: a region of the South American subduction zone lying between Arica city and the Mejillones Peninsula. It is believed that this part of the subduction zone has not experienced a large earthquake since 1877. Thanks to the identification of this seismic gap, the north of Chile was well instrumented before the Pisagua earthquake, including the Integrated Plate boundary Observatory Chile (IPOC) network and the Chilean local network installed by the Centro Sismologico Nacional (CSN). These instruments were able to record the full foreshock and aftershock sequences, allowing a unique opportunity to study the nucleation process of large megathrust earthquakes. To improve azimuthal coverage of the Pisagua seismic sequence, after the earthquake, in collaboration with the Instituto Geofisico del Peru (IGP) we installed a temporary seismic network in south of Peru. The network comprised 12 short-period stations located in the coastal area between Moquegua and Tacna and they were operative from 1st May 2014. We also installed three stations on the slopes of the Ticsiani volcano to monitor any possible change in volcanic activity following the Pisagua earthquake. In this work we analysed the continuous seismic data recorded by CSN and IPOC networks from 1 March to 30 June to obtain the catalogue of the sequence, including foreshocks and aftershocks. Using an automatic algorithm based in STA/LTA we obtained the picks for P and S waves. Association in time and space defined the events and computed an initial location using Hypo71 and the 1D local velocity model. More than 11,000 events were identified with this method for the whole period, but we selected the best resolved events that include more than 7 observed arrivals with at least 2 S picks of them, to relocate these events using NonLinLoc software. For the main events of the sequence we carefully estimate event locations and we obtained

  10. Geological and historical evidence of irregular recurrent earthquakes in Japan.

    Science.gov (United States)

    Satake, Kenji

    2015-10-28

    Great (M∼8) earthquakes repeatedly occur along the subduction zones around Japan and cause fault slip of a few to several metres releasing strains accumulated from decades to centuries of plate motions. Assuming a simple 'characteristic earthquake' model that similar earthquakes repeat at regular intervals, probabilities of future earthquake occurrence have been calculated by a government committee. However, recent studies on past earthquakes including geological traces from giant (M∼9) earthquakes indicate a variety of size and recurrence interval of interplate earthquakes. Along the Kuril Trench off Hokkaido, limited historical records indicate that average recurrence interval of great earthquakes is approximately 100 years, but the tsunami deposits show that giant earthquakes occurred at a much longer interval of approximately 400 years. Along the Japan Trench off northern Honshu, recurrence of giant earthquakes similar to the 2011 Tohoku earthquake with an interval of approximately 600 years is inferred from historical records and tsunami deposits. Along the Sagami Trough near Tokyo, two types of Kanto earthquakes with recurrence interval of a few hundred years and a few thousand years had been recognized, but studies show that the recent three Kanto earthquakes had different source extents. Along the Nankai Trough off western Japan, recurrence of great earthquakes with an interval of approximately 100 years has been identified from historical literature, but tsunami deposits indicate that the sizes of the recurrent earthquakes are variable. Such variability makes it difficult to apply a simple 'characteristic earthquake' model for the long-term forecast, and several attempts such as use of geological data for the evaluation of future earthquake probabilities or the estimation of maximum earthquake size in each subduction zone are being conducted by government committees. © 2015 The Author(s).

  11. The music of earthquakes and Earthquake Quartet #1

    Science.gov (United States)

    Michael, Andrew J.

    2013-01-01

    Earthquake Quartet #1, my composition for voice, trombone, cello, and seismograms, is the intersection of listening to earthquakes as a seismologist and performing music as a trombonist. Along the way, I realized there is a close relationship between what I do as a scientist and what I do as a musician. A musician controls the source of the sound and the path it travels through their instrument in order to make sound waves that we hear as music. An earthquake is the source of waves that travel along a path through the earth until reaching us as shaking. It is almost as if the earth is a musician and people, including seismologists, are metaphorically listening and trying to understand what the music means.

  12. The Klamath Falls, Oregon, earthquakes on September 20, 1993

    Science.gov (United States)

    Brantley, S.R.

    1993-01-01

    The strongest earthquake to strike Oregon in more than 50 yrs struck the southern part of the State on September 20, 1993. These shocks, a magnitude 5.9 earthquake at 8:28pm and a magnitude 6.0 earthquake at 10:45pm, were the opening salvo in a swarm of earthquakes that continued for more than three months. During this period, several thousand aftershocks, many strong enough to be felt, were recorded by seismographs.

  13. Seismicity and earthquake risk in western Sicily

    Directory of Open Access Journals (Sweden)

    P. COSENTINO

    1978-06-01

    Full Text Available The seismicity and the earthquake risk in Western Sicily are here
    evaluated on the basis of the experimental data referring to the historical
    and instrumentally recorded earthquakes in this area (from 1248
    up to 1968, which have been thoroughly collected, analyzed, tested and
    normalized in order to assure the quasi-stationarity of the series of
    events.
    The approximated magnitude values — obtained by means of a compared
    analysis of the magnitude and epicentral intensity values of the
    latest events — have allowed to study the parameters of the frequency-
    magnitude relation with both the classical exponential model and
    the truncated exponential one previously proposed by the author.
    So, the basic parameters, including the maximum possible regional
    magnitude, have been estimated by means of different procedures, and
    their behaviours have been studied as functions of the threshold magnitude.

  14. Connecting slow earthquakes to huge earthquakes.

    Science.gov (United States)

    Obara, Kazushige; Kato, Aitaro

    2016-07-15

    Slow earthquakes are characterized by a wide spectrum of fault slip behaviors and seismic radiation patterns that differ from those of traditional earthquakes. However, slow earthquakes and huge megathrust earthquakes can have common slip mechanisms and are located in neighboring regions of the seismogenic zone. The frequent occurrence of slow earthquakes may help to reveal the physics underlying megathrust events as useful analogs. Slow earthquakes may function as stress meters because of their high sensitivity to stress changes in the seismogenic zone. Episodic stress transfer to megathrust source faults leads to an increased probability of triggering huge earthquakes if the adjacent locked region is critically loaded. Careful and precise monitoring of slow earthquakes may provide new information on the likelihood of impending huge earthquakes. Copyright © 2016, American Association for the Advancement of Science.

  15. Large earthquakes and creeping faults

    Science.gov (United States)

    Harris, Ruth A.

    2017-01-01

    Faults are ubiquitous throughout the Earth's crust. The majority are silent for decades to centuries, until they suddenly rupture and produce earthquakes. With a focus on shallow continental active-tectonic regions, this paper reviews a subset of faults that have a different behavior. These unusual faults slowly creep for long periods of time and produce many small earthquakes. The presence of fault creep and the related microseismicity helps illuminate faults that might not otherwise be located in fine detail, but there is also the question of how creeping faults contribute to seismic hazard. It appears that well-recorded creeping fault earthquakes of up to magnitude 6.6 that have occurred in shallow continental regions produce similar fault-surface rupture areas and similar peak ground shaking as their locked fault counterparts of the same earthquake magnitude. The behavior of much larger earthquakes on shallow creeping continental faults is less well known, because there is a dearth of comprehensive observations. Computational simulations provide an opportunity to fill the gaps in our understanding, particularly of the dynamic processes that occur during large earthquake rupture and arrest.

  16. Rapid Seismic Deployment for Capturing Aftershocks of the September 2017 Tehuantepec, Mexico (M=8.1) and Morelos-Puebla (M=7.1), Mexico Earthquakes

    Science.gov (United States)

    Velasco, A. A.; Karplus, M. S.; Dena, O.; Gonzalez-Huizar, H.; Husker, A. L.; Perez-Campos, X.; Calo, M.; Valdes, C. M.

    2017-12-01

    The September 7 Tehuantepec, Mexico (M=8.1) and the September 19 Morelos-Puebla, Mexico (M=7.1) earthquakes ruptured with extensional faulting within the Cocos Plate at 70-km and 50-km depth, as it subducts beneath the continental North American Plate. Both earthquakes caused significant damage and loss of life. These events were followed by a M=6.1 extensional earthquake at only 10-km depth in Oaxaca on September 23, 2017. While the Morelos-Puebla earthquake was likely too far away to be statically triggered by the Tehuantepec earthquake, initial Coulomb stress analyses show that the M=6.1 event may have been an aftershock of the Tehuantepec earthquake. Many questions remain about these earthquakes, including: Did the Cocos Plate earthquakes load the upper plate, and could they possibly trigger an equal or larger earthquake on the plate interface? Are these the result of plate bending? Do the aftershocks migrate to the locked zone in the subduction zone? Why did the intermediate depth earthquakes create so much damage? Are these earthquakes linked by dynamic stresses? Is it possible that a potential slow-slip event triggered both events? To address some of these questions, we deployed 10 broadband seismometers near the epicenter of the Tehuantepec, Mexico earthquake and 51 UTEP-owned nodes (5-Hz, 3-component geophones) to record aftershocks and augment networks deployed by the Universidad Nacional Autónoma de México (UNAM). The 10 broadband instruments will be deployed for 6 months, while the nodes were deployed 25 days. The relative ease-of-deployment and larger numbers of the nodes allowed us to deploy them quickly in the area near the M=6.1 Oaxaca earthquake, just a few days after that earthquake struck. We deployed them near the heavily-damaged cities of Juchitan, Ixtaltepec, and Ixtepec as well as in Tehuantepec and Salina Cruz, Oaxaca in order to test their capabilities for site characterization and aftershock studies. This is the first test of these

  17. Electrostatically actuated resonant switches for earthquake detection

    KAUST Repository

    Ramini, Abdallah H.; Masri, Karim M.; Younis, Mohammad I.

    2013-01-01

    action can be functionalized for useful functionalities, such as shutting off gas pipelines in the case of earthquakes, or can be used to activate a network of sensors for seismic activity recording in health monitoring applications. By placing a

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

    Science.gov (United States)

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

    2017-12-01

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

  19. Twitter earthquake detection: earthquake monitoring in a social world

    Directory of Open Access Journals (Sweden)

    Daniel C. Bowden

    2011-06-01

    Full Text Available The U.S. Geological Survey (USGS is investigating how the social networking site Twitter, a popular service for sending and receiving short, public text messages, can augment USGS earthquake response products and the delivery of hazard information. Rapid detection and qualitative assessment of shaking events are possible because people begin sending public Twitter messages (tweets with in tens of seconds after feeling shaking. Here we present and evaluate an earthquake detection procedure that relies solely on Twitter data. A tweet-frequency time series constructed from tweets containing the word “earthquake” clearly shows large peaks correlated with the origin times of widely felt events. To identify possible earthquakes, we use a short-term-average, long-term-average algorithm. When tuned to a moderate sensitivity, the detector finds 48 globally-distributed earthquakes with only two false triggers in five months of data. The number of detections is small compared to the 5,175 earthquakes in the USGS global earthquake catalog for the same five-month time period, and no accurate location or magnitude can be assigned based on tweet data alone. However, Twitter earthquake detections are not without merit. The detections are generally caused by widely felt events that are of more immediate interest than those with no human impact. The detections are also fast; about 75% occur within two minutes of the origin time. This is considerably faster than seismographic detections in poorly instrumented regions of the world. The tweets triggering the detections also provided very short first-impression narratives from people who experienced the shaking.

  20. Chapter A. The Loma Prieta, California, Earthquake of October 17, 1989 - Strong Ground Motion

    Science.gov (United States)

    Borcherdt, Roger D.

    1994-01-01

    Strong ground motion generated by the Loma Prieta, Calif., earthquake (MS~7.1) of October 17, 1989, resulted in at least 63 deaths, more than 3,757 injuries, and damage estimated to exceed $5.9 billion. Strong ground motion severely damaged critical lifelines (freeway overpasses, bridges, and pipelines), caused severe damage to poorly constructed buildings, and induced a significant number of ground failures associated with liquefaction and landsliding. It also caused a significant proportion of the damage and loss of life at distances as far as 100 km from the epicenter. Consequently, understanding the characteristics of the strong ground motion associated with the earthquake is fundamental to understanding the earthquake's devastating impact on society. The papers assembled in this chapter address this problem. Damage to vulnerable structures from the earthquake varied substantially with the distance from the causative fault and the type of underlying geologic deposits. Most of the damage and loss of life occurred in areas underlain by 'soft soil'. Quantifying these effects is important for understanding the tragic concentrations of damage in such areas as Santa Cruz and the Marina and Embarcadero Districts of San Francisco, and the failures of the San Francisco-Oakland Bay Bridge and the Interstate Highway 880 overpass. Most importantly, understanding these effects is a necessary prerequisite for improving mitigation measures for larger earthquakes likely to occur much closer to densely urbanized areas in the San Francisco Bay region. The earthquake generated an especially important data set for understanding variations in the severity of strong ground motion. Instrumental strong-motion recordings were obtained at 131 sites located from about 6 to 175 km from the rupture zone. This set of recordings, the largest yet collected for an event of this size, was obtained from sites on various geologic deposits, including a unique set on 'soft soil' deposits

  1. Defeating Earthquakes

    Science.gov (United States)

    Stein, R. S.

    2012-12-01

    The 2004 M=9.2 Sumatra earthquake claimed what seemed an unfathomable 228,000 lives, although because of its size, we could at least assure ourselves that it was an extremely rare event. But in the short space of 8 years, the Sumatra quake no longer looks like an anomaly, and it is no longer even the worst disaster of the Century: 80,000 deaths in the 2005 M=7.6 Pakistan quake; 88,000 deaths in the 2008 M=7.9 Wenchuan, China quake; 316,000 deaths in the M=7.0 Haiti, quake. In each case, poor design and construction were unable to withstand the ferocity of the shaken earth. And this was compounded by inadequate rescue, medical care, and shelter. How could the toll continue to mount despite the advances in our understanding of quake risk? The world's population is flowing into megacities, and many of these migration magnets lie astride the plate boundaries. Caught between these opposing demographic and seismic forces are 50 cities of at least 3 million people threatened by large earthquakes, the targets of chance. What we know for certain is that no one will take protective measures unless they are convinced they are at risk. Furnishing that knowledge is the animating principle of the Global Earthquake Model, launched in 2009. At the very least, everyone should be able to learn what his or her risk is. At the very least, our community owes the world an estimate of that risk. So, first and foremost, GEM seeks to raise quake risk awareness. We have no illusions that maps or models raise awareness; instead, earthquakes do. But when a quake strikes, people need a credible place to go to answer the question, how vulnerable am I, and what can I do about it? The Global Earthquake Model is being built with GEM's new open source engine, OpenQuake. GEM is also assembling the global data sets without which we will never improve our understanding of where, how large, and how frequently earthquakes will strike, what impacts they will have, and how those impacts can be lessened by

  2. Explanation of earthquake response spectra

    OpenAIRE

    Douglas, John

    2017-01-01

    This is a set of five slides explaining how earthquake response spectra are derived from strong-motion records and simple models of structures and their purpose within seismic design and assessment. It dates from about 2002 and I have used it in various introductory lectures on engineering seismology.

  3. Earthquake Early Warning Systems

    OpenAIRE

    Pei-Yang Lin

    2011-01-01

    Because of Taiwan’s unique geographical environment, earthquake disasters occur frequently in Taiwan. The Central Weather Bureau collated earthquake data from between 1901 and 2006 (Central Weather Bureau, 2007) and found that 97 earthquakes had occurred, of which, 52 resulted in casualties. The 921 Chichi Earthquake had the most profound impact. Because earthquakes have instant destructive power and current scientific technologies cannot provide precise early warnings in advance, earthquake ...

  4. Urban MEMS based seismic network for post-earthquakes rapid disaster assessment

    Science.gov (United States)

    D'Alessandro, Antonino; Luzio, Dario; D'Anna, Giuseppe

    2014-05-01

    Life losses following disastrous earthquake depends mainly by the building vulnerability, intensity of shaking and timeliness of rescue operations. In recent decades, the increase in population and industrial density has significantly increased the exposure to earthquakes of urban areas. The potential impact of a strong earthquake on a town center can be reduced by timely and correct actions of the emergency management centers. A real time urban seismic network can drastically reduce casualties immediately following a strong earthquake, by timely providing information about the distribution of the ground shaking level. Emergency management centers, with functions in the immediate post-earthquake period, could be use this information to allocate and prioritize resources to minimize loss of human life. However, due to the high charges of the seismological instrumentation, the realization of an urban seismic network, which may allow reducing the rate of fatalities, has not been achieved. Recent technological developments in MEMS (Micro Electro-Mechanical Systems) technology could allow today the realization of a high-density urban seismic network for post-earthquakes rapid disaster assessment, suitable for the earthquake effects mitigation. In the 1990s, MEMS accelerometers revolutionized the automotive-airbag system industry and are today widely used in laptops, games controllers and mobile phones. Due to their great commercial successes, the research into and development of MEMS accelerometers are actively pursued around the world. Nowadays, the sensitivity and dynamics of these sensors are such to allow accurate recording of earthquakes with moderate to strong magnitude. Due to their low cost and small size, the MEMS accelerometers may be employed for the realization of high-density seismic networks. The MEMS accelerometers could be installed inside sensitive places (high vulnerability and exposure), such as schools, hospitals, public buildings and places of

  5. Reassessment of source parameters for three major earthquakes in the East African rift system from historical seismograms and bulletins

    Directory of Open Access Journals (Sweden)

    O. Kulhánek

    2000-06-01

    Full Text Available Source parameters for three majo earthquakes in the East African rift are re-computed from historical seismograms and bulletins. The main shock and the largest foreshock of the August 25, 1906 earthquake sequence in the main Ethiopian rift are re-located on the eastern shoulder of the rift segment.The magnitude of the main shock is estimated to be 6.5 (Mw from spectral analysis. The December 13, 1910 earthquake in the Rukwa rift (Western Tanzania indicated a significant strike-slip component from teleseismcs body-waveform inversion for fault mechanism and seismic moment. The January 6, 1928 earthquake in the Gregory rift (Kenya showed a multiple rupture process and unusually long duration for a size of 6.6(Mw. The May 20, 1990 earthquake in Southern Sudan, mentioned merely for the sake of comparison, is the largest of all instrumentally recorded events in the East African rift system. Despite the fact that the mode of deformation in the continental rift is predominantly of extensional nature, the three largest earthquakes known to occur in the circum-Tanzanian craton have shallow focal depths and significant strike-slip component in their fault mechanisms. This and similar works will enrich the database for seismic hazard assessment in East Africa.

  6. Determine Earthquake Rupture Directivity Using Taiwan TSMIP Strong Motion Waveforms

    Science.gov (United States)

    Chang, Kaiwen; Chi, Wu-Cheng; Lai, Ying-Ju; Gung, YuanCheng

    2013-04-01

    Inverting seismic waveforms for the finite fault source parameters is important for studying the physics of earthquake rupture processes. It is also significant to image seismogenic structures in urban areas. Here we analyze the finite-source process and test for the causative fault plane using the accelerograms recorded by the Taiwan Strong-Motion Instrumentation Program (TSMIP) stations. The point source parameters for the mainshock and aftershocks were first obtained by complete waveform moment tensor inversions. We then use the seismograms generated by the aftershocks as empirical Green's functions (EGFs) to retrieve the apparent source time functions (ASTFs) of near-field stations using projected Landweber deconvolution approach. The method for identifying the fault plane relies on the spatial patterns of the apparent source time function durations which depend on the angle between rupture direction and the take-off angle and azimuth of the ray. These derived duration patterns then are compared with the theoretical patterns, which are functions of the following parameters, including focal depth, epicentral distance, average crustal 1D velocity, fault plane attitude, and rupture direction on the fault plane. As a result, the ASTFs derived from EGFs can be used to infer the ruptured fault plane and the rupture direction. Finally we used part of the catalogs to study important seismogenic structures in the area near Chiayi, Taiwan, where a damaging earthquake has occurred about a century ago. The preliminary results show a strike-slip earthquake on 22 October 1999 (Mw 5.6) has ruptured unilaterally toward SSW on a sub-vertical fault. The procedure developed from this study can be applied to other strong motion waveforms recorded from other earthquakes to better understand their kinematic source parameters.

  7. The earthquakes of stable continental regions. Volume 2: Appendices A to E. Final report

    International Nuclear Information System (INIS)

    Johnston, A.C.; Kanter, L.R.; Coppersmith, K.J.; Cornell, C.A.

    1994-12-01

    The objectives of the study were to develop a comprehensive database of earthquakes in stable continental regions (SCRs) and to statistically examine use of the database for the assessment of large earthquake potential. We identified nine major and several minor SCRs worldwide and compiled a database of geologic characteristics of tectonic domains within each SCR. We examined all available earthquake data from SCRs, from historical accounts of events with no instrumental ground-motion data to present-day instrumentally recorded events. In all, 1,385 events were analyzed. Using moment magnitude 4.5 as the lower bound threshold for inclusion in the database, 870 were assigned to an SCR, 124 were found to be transitional to an SCR, and 391 were examined, but rejected. We then performed a seismotectonic analysis to determine what distinguishes seismic activity in SCRs from other types of crust, such as active plate margins or active continental regions. General observations are: (1) SCRs comprise nearly two-thirds of all continental crust of which 25% is considered to be extended (i.e., rifted); (2) the majority of seismic energy release and the largest earthquakes in SCRs have occurred in extended crust; and (3) active plate margins release seismic energy at a rate per unit area approximately 7,000 times the average for non-extended SCRs. Finally, results of a statistical examination of distributions of historical maximum earthquakes between different crustal domain types indicated that additional information is needed in order to adequately constrain estimates of maximum earthquakes for any given region. Thus, a Bayesian approach was developed in which statistical constraints from the database were used to develop a prior distribution, which may then be combined with source-specific information to constrain maximum magnitude assessments for use in probabilistic seismic hazard analyses

  8. Real Time Earthquake Information System in Japan

    Science.gov (United States)

    Doi, K.; Kato, T.

    2003-12-01

    An early earthquake notification system in Japan had been developed by the Japan Meteorological Agency (JMA) as a governmental organization responsible for issuing earthquake information and tsunami forecasts. The system was primarily developed for prompt provision of a tsunami forecast to the public with locating an earthquake and estimating its magnitude as quickly as possible. Years after, a system for a prompt provision of seismic intensity information as indices of degrees of disasters caused by strong ground motion was also developed so that concerned governmental organizations can decide whether it was necessary for them to launch emergency response or not. At present, JMA issues the following kinds of information successively when a large earthquake occurs. 1) Prompt report of occurrence of a large earthquake and major seismic intensities caused by the earthquake in about two minutes after the earthquake occurrence. 2) Tsunami forecast in around three minutes. 3) Information on expected arrival times and maximum heights of tsunami waves in around five minutes. 4) Information on a hypocenter and a magnitude of the earthquake, the seismic intensity at each observation station, the times of high tides in addition to the expected tsunami arrival times in 5-7 minutes. To issue information above, JMA has established; - An advanced nationwide seismic network with about 180 stations for seismic wave observation and about 3,400 stations for instrumental seismic intensity observation including about 2,800 seismic intensity stations maintained by local governments, - Data telemetry networks via landlines and partly via a satellite communication link, - Real-time data processing techniques, for example, the automatic calculation of earthquake location and magnitude, the database driven method for quantitative tsunami estimation, and - Dissemination networks, via computer-to-computer communications and facsimile through dedicated telephone lines. JMA operationally

  9. Estimation of site effects in Higashinada Ward, Kobe City using aftershock records of the 1995 Hyogo-Ken Nanbu Earthquake; Hyogoken nanbu jishin no yoshin kiroku wo mochiita Kobeshihigashinadaku no jiban zofuku tokusei no hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Kurita, K.; Yamanaka, H.; Seo, K. [Tokyo Inst. of Tech. (Japan)

    1998-07-30

    Source spectra and site effects are separated using the aftershock records, and the characteristics of short period earthquake motion in Higashinada Ward, Kobe City including the area to the south of seismic intensity 7 area are investigated placing emphasis on how far the site effects can be explained by 1-D ground structure. The shape and amplitude of the site effect of KNN and KYC located outside the seismic intensity 7 area can be explained fairly well by 1-D multiple reflection theory of S wave. However, peaks near 3 to 4Hz of KNN and UOZ in seismic intensity 7 area can not be explained. This suggests that the site effects of seismic intensity 7 area obtained by the aftershock records might include 2-D effects of underground structure. Inversion is performed using site effects as the objective functions to determine S wave velocity structure and Qs in the sedimentary layer. S wave velocity structure shows no systematical difference from those of the past models. 22 refs., 13 figs., 2 tabs.

  10. Marmara Island earthquakes, of 1265 and 1935; Turkey

    Directory of Open Access Journals (Sweden)

    Y. Altınok

    2006-01-01

    Full Text Available The long-term seismicity of the Marmara Sea region in northwestern Turkey is relatively well-recorded. Some large and some of the smaller events are clearly associated with fault zones known to be seismically active, which have distinct morphological expressions and have generated damaging earthquakes before and later. Some less common and moderate size earthquakes have occurred in the vicinity of the Marmara Islands in the west Marmara Sea. This paper presents an extended summary of the most important earthquakes that have occurred in 1265 and 1935 and have since been known as the Marmara Island earthquakes. The informative data and the approaches used have therefore the potential of documenting earthquake ruptures of fault segments and may extend the records kept on earthquakes far before known history, rock falls and abnormal sea waves observed during these events, thus improving hazard evaluations and the fundamental understanding of the process of an earthquake.

  11. The 2011 Mineral, VA M5.8 Earthquake Ground Motions and Stress Drop: An Important Contribution to the NGA East Ground Motion Database

    Science.gov (United States)

    Cramer, C. H.; Kutliroff, J.; Dangkua, D.

    2011-12-01

    The M5.8 Mineral, Virginia earthquake of August 23, 2011 is the largest instrumentally recorded earthquake in eastern North America since the 1988 M5.9 Saguenay, Canada earthquake. Historically, a similar magnitude earthquake occurred on May 31, 1897 at 18:58 UCT in western Virginia west of Roanoke. Paleoseismic evidence for larger magnitude earthquakes has also been found in the central Virginia region. The Next Generation Attenuation (NGA) East project to develop new ground motion prediction equations for stable continental regions (SCRs), including eastern North America (ENA), is ongoing at the Pacific Earthquake Engineering Research Center funded by the U.S. Nuclear Regulatory Commission, the U.S. Geological Survey, the Electric Power Research Institute, and the U.S. Department of Energy. The available recordings from the M5.8 Virginia are being added to the NGA East ground motion database. Close in (less than 100 km) strong motion recordings are particularly interesting for both ground motion and stress drop estimates as most close-in broadband seismometers clipped on the mainshock. A preliminary estimate for earthquake corner frequency for the M5.8 Virginia earthquake of ~0.7 Hz has been obtained from a strong motion record 57 km from the mainshock epicenter. For a M5.8 earthquake this suggests a Brune stress drop of ~300 bars for the Virginia event. Very preliminary comparisons using accelerometer data suggest the ground motions from the M5.8 Virginia earthquake agree well with current ENA ground motion prediction equations (GMPEs) at short periods (PGA, 0.2 s) and are below the GMPEs at longer periods (1.0 s), which is the same relationship seen from other recent M5 ENA earthquakes. We will present observed versus GMPE ground motion comparisons for all the ground motion observations and stress drop estimates from strong motion recordings at distances less than 100 km. A review of the completed NGA East ENA ground motion database will also be provided.

  12. Earthquake, GIS and multimedia. The 1883 Casamicciola earthquake

    Directory of Open Access Journals (Sweden)

    M. Rebuffat

    1995-06-01

    Full Text Available A series of multimedia monographs concerning the main seismic events that have affected the Italian territory are in the process of being produced for the Documental Integrated Multimedia Project (DIMP started by the Italian National Seismic Survey (NSS. The purpose of the project is to reconstruct the historical record of earthquakes and promote an earthquake public education. Producing the monographs. developed in ARC INFO and working in UNIX. involved designing a special filing and management methodology to integrate heterogeneous information (images, papers, cartographies, etc.. This paper describes the possibilities of a GIS (Geographic Information System in the filing and management of documental information. As an example we present the first monograph on the 1883 Casamicciola earthquake. on the island of Ischia (Campania, Italy. This earthquake is particularly interesting for the following reasons: I historical-cultural context (first destructive seismic event after the unification of Italy; 2 its features (volcanic earthquake; 3 the socioeconomic consequences caused at such an important seaside resort.

  13. Smartphone MEMS accelerometers and earthquake early warning

    Science.gov (United States)

    Kong, Q.; Allen, R. M.; Schreier, L.; Kwon, Y. W.

    2015-12-01

    The low cost MEMS accelerometers in the smartphones are attracting more and more attentions from the science community due to the vast number and potential applications in various areas. We are using the accelerometers inside the smartphones to detect the earthquakes. We did shake table tests to show these accelerometers are also suitable to record large shakings caused by earthquakes. We developed an android app - MyShake, which can even distinguish earthquake movements from daily human activities from the recordings recorded by the accelerometers in personal smartphones and upload trigger information/waveform to our server for further analysis. The data from these smartphones forms a unique datasets for seismological applications, such as earthquake early warning. In this talk I will layout the method we used to recognize earthquake-like movement from single smartphone, and the overview of the whole system that harness the information from a network of smartphones for rapid earthquake detection. This type of system can be easily deployed and scaled up around the global and provides additional insights of the earthquake hazards.

  14. The wireless networking system of Earthquake precursor mobile field observation

    Science.gov (United States)

    Wang, C.; Teng, Y.; Wang, X.; Fan, X.; Wang, X.

    2012-12-01

    The mobile field observation network could be real-time, reliably record and transmit large amounts of data, strengthen the physical signal observations in specific regions and specific period, it can improve the monitoring capacity and abnormal tracking capability. According to the features of scatter everywhere, a large number of current earthquake precursor observation measuring points, networking technology is based on wireless broadband accessing McWILL system, the communication system of earthquake precursor mobile field observation would real-time, reliably transmit large amounts of data to the monitoring center from measuring points through the connection about equipment and wireless accessing system, broadband wireless access system and precursor mobile observation management center system, thereby implementing remote instrument monitoring and data transmition. At present, the earthquake precursor field mobile observation network technology has been applied to fluxgate magnetometer array geomagnetic observations of Tianzhu, Xichang,and Xinjiang, it can be real-time monitoring the working status of the observational instruments of large area laid after the last two or three years, large scale field operation. Therefore, it can get geomagnetic field data of the local refinement regions and provide high-quality observational data for impending earthquake tracking forecast. Although, wireless networking technology is very suitable for mobile field observation with the features of simple, flexible networking etc, it also has the phenomenon of packet loss etc when transmitting a large number of observational data due to the wireless relatively weak signal and narrow bandwidth. In view of high sampling rate instruments, this project uses data compression and effectively solves the problem of data transmission packet loss; Control commands, status data and observational data transmission use different priorities and means, which control the packet loss rate within

  15. Peak ground motion distribution in Romania due to Vrancea earthquakes

    International Nuclear Information System (INIS)

    Grecu, B.; Rizescu, M.; Radulian, M.; Mandrescu, N.; Moldovan, I.-A.; Bonjer, K.-P

    2002-01-01

    Vrancea is a particular seismic region situated at the SE-Carpathians bend (Romania). It is characterized by persistent seismicity in a concentrated focal volume, at depths of 60-200 km, with 2 to 3 major earthquakes per century (M W >7). The purpose of our study is to investigate in detail the ground motion patterns for small and moderate Vrancea events (M W = 3.5 to 5.3) occurred during 1999, taking advantage of the unique data set offered by the Calixto'99 Project and the permanent Vrancea-K2 network (150 stations). The observed patterns are compared with available macroseismic maps of large Vrancea earthquakes, showing similar general patterns elongated in the NE-SW direction which mimic the S-waves source radiation, but patches with pronounced maxima are also evidenced rather far from the epicenter, at the NE and SW edges of the Focsani sedimentary basin, as shown firstly by Atanasiu (1961). This feature is also visible on instrumental data of strong events (Mandrescu and Radulian, 1999) as well as for moderate events recently recorded by digital K2 network (Bonjer et al., 2001) and correlates with the distribution of predominant response frequencies of shallow sedimentary layers. The influence of the local structure and/or focussing effects, caused by deeper lithospheric structure, on the observed site effects and the implications on the seismic hazard assessment for Vrancea earthquakes are discussed. (authors)

  16. The Preliminary Study of the 4 March 2010 Mw 6.3 Jiasian, Taiwan Earthquake Sequence

    Directory of Open Access Journals (Sweden)

    Hsin-Hua Huang

    2011-01-01

    Full Text Available On 4 March 2010, an inland Mw 6.3 earthquake occurred near the town of Jiasian in Kaohsiung County, Taiwan causing large ground shaking and extensive damage. In this study, we integrate the records from the Central Weather Bureau Seismic Network (CWBSN and Taiwan Strong Motion Instrumentation Program (TSMIP to obtain the relocated earthquake sequence and its first-motion focal mechanisms. This dataset offers us precise and reliable results which suggest a focal depth of 23 km and a possible fault plane of strike 313¢X, dip 41¢X, and rake 42¢X for the Jiasian earthquake. This fault plane significantly differs from the N-S striking Chaochou Fault (CCF as well as the principal trend of Taiwan orogenic belt, and should be an undiscovered fault in southern Taiwan. The relocated Jiasian earthquake sequence initiating from the 23-km-deep mainshock and terminating at around 10 km in depth also indicates it is a blind fault. Peak ground acceleration (PGA and peak ground velocity (PGV recorded by the TSMIP stations reveal a distinct NW-SE-shape pattern from the epicenter area toward the Chiayi region, likely due to the directivity and site effects. Such phenomena should be considered for future regional hazard assessments.

  17. Vrancea earthquakes. Courses for specific actions to mitigate seismic risk

    International Nuclear Information System (INIS)

    Marmureanu, Gheorghe; Marmureanu, Alexandru

    2005-01-01

    Earthquakes in the Carpathian-Pannonian region are confined to the crust, except the Vrancea zone, where earthquakes with focal depth down to 200 Km occur. For example, the ruptured area migrated from 150 km to 180 km (November 10,1940, M w = 7.7) from 90 km to 110 km (March 4, 1977, M w 7.4), from 130 km to 150 km (August 30, 1986, M w = 7.1) and from 70 km to 90 km (May 30, 1990, M w = 6.9) depth. The depth interval between 110 km and 130 km remains not ruptured since 1802, October 26, when it was the strongest earthquake occurred in this part of Central Europe. The magnitude is assumed to be M w = 7.9 - 8.0 and this depth interval is a natural candidate for the next strong Vrancea event. While no country in the world is entirely safe, the lack of capacity to limit the impact of seismic hazards remains a major burden for all countries and while the world has witnessed an exponential increase in human and material losses due to natural disasters given by earthquakes, there is a need to reverse trends in seismic risk mitigation to future events. Main courses for specific actions to mitigate the seismic risk given by strong deep Vrancea earthquakes should be considered as key for development actions: - Early warning system for industrial facilities. Early warning is more than a technological instrument to detect, monitor and submit warnings. It should become part of a management information system for decision-making in the context of national institutional frameworks for disaster management and part of national and local strategies and programmers for risk mitigation; - Prediction program of Vrancea strong earthquakes of short and long term; - Hazard seismic map of Romania. The wrong assessment of the seismic hazard can lead to dramatic situations as those from Bucharest or Kobe. Before the 1977 Vrancea earthquake, the city of Bucharest was designed to intensity I = VII (MMI) and the real intensity was I = IX1/2-X (MMI); - Seismic microzonation of large populated

  18. Earthquake location in island arcs

    Science.gov (United States)

    Engdahl, E.R.; Dewey, J.W.; Fujita, K.

    1982-01-01

    -velocity lithospheric slab. In application, JHD has the practical advantage that it does not require the specification of a theoretical velocity model for the slab. Considering earthquakes within a 260 km long by 60 km wide section of the Aleutian main thrust zone, our results suggest that the theoretical velocity structure of the slab is presently not sufficiently well known that accurate locations can be obtained independently of locally recorded data. Using a locally recorded earthquake as a calibration event, JHD gave excellent results over the entire section of the main thrust zone here studied, without showing a strong effect that might be attributed to spatially varying source-station anomalies. We also calibrated the ray-tracing method using locally recorded data and obtained results generally similar to those obtained by JHD. ?? 1982.

  19. Damping in building structures during earthquakes: test data and modeling

    International Nuclear Information System (INIS)

    Coats, D.W. Jr.

    1982-01-01

    A review and evaluation of the state-of-the-art of damping in building structures during earthquakes is presented. The primary emphasis is in the following areas: 1) the evaluation of commonly used mathematical techniques for incorporating damping effects in both simple and complex systems; 2) a compilation and interpretation of damping test data; and 3) an evaluation of structure testing methods, building instrumentation practices, and an investigation of rigid-body rotation effects on damping values from test data. A literature review provided the basis for evaluating mathematical techiques used to incorporate earthquake induced damping effects in simple and complex systems. A discussion on the effectiveness of damping, as a function of excitation type, is also included. Test data, from a wide range of sources, has been compiled and interpreted for buidings, nuclear power plant structures, piping, equipment, and isolated structural elements. Test methods used to determine damping and frequency parameters are discussed. In particular, the advantages and disadvantages associated with the normal mode and transfer function approaches are evaluated. Additionally, the effect of rigid-body rotations on damping values deduced from strong-motion building response records is investigated. A discussion of identification techniques typically used to determine building parameters (frequency and damping) from strong motion records is included. Finally, an analytical demonstration problem is presented to quantify the potential error in predicting fixed-base structural frequency and damping values from strong motion records, when rigid-body rotations are not properly accounted for

  20. A Demonstration of an Improved Filtering Technique for Analyzing Climate Records via Comparisons of Satellite MSU/AMSU Instrument Temperature Products from Three Research Groups

    Science.gov (United States)

    Swanson, R. E.

    2017-12-01

    Climate data records typically exhibit considerable variation over short time scales both from natural variability and from instrumentation issues. The use of linear least squares regression can provide overall trend information from noisy data, however assessing intermediate time periods can also provide useful information unavailable from basic trend calculations. Extracting the short term information in these data for assessing changes to climate or for comparison of data series from different sources requires the application of filters to separate short period variations from longer period trends. A common method used to smooth data is the moving average, which is a simple digital filter that can distort the resulting series due to the aliasing of the sampling period into the output series. We utilized Hamming filters to compare MSU/AMSU satellite time series developed by three research groups (UAH, RSS and NOAA STAR), the results published in January 2017 [http://journals.ametsoc.org/doi/abs/10.1175/JTECH-D-16-0121.1]. Since the last release date (July 2016) for the data analyzed in that paper, some of these groups have updated their analytical procedures and additional months of data are available to extend the series. An updated analysis of these data using the latest data releases available from each group is to be presented. Improved graphics will be employed to provide a clearer visualization of the differences between each group's results. As in the previous paper, the greatest difference between the UAH TMT series and those from the RSS and NOAA data appears during the early period of data from the MSU instruments before about 2003, as shown in the attached figure, and preliminary results indicate this pattern continues. Also to be presented are other findings regarding seasonal changes which were not included in the previous study.

  1. Money matters: Rapid post-earthquake financial decision-making

    Science.gov (United States)

    Wald, David J.; Franco, Guillermo

    2016-01-01

    Post-earthquake financial decision-making is a realm beyond that of many people. In the immediate aftermath of a damaging earthquake, billions of dollars of relief, recovery, and insurance funds are in the balance through new financial instruments that allow those with resources to hedge against disasters and those at risk to limit their earthquake losses and receive funds for response and recovery.

  2. Application of τc*Pd in earthquake early warning

    Science.gov (United States)

    Huang, Po-Lun; Lin, Ting-Li; Wu, Yih-Min

    2015-03-01

    Rapid assessment of damage potential and size of an earthquake at the station is highly demanded for onsite earthquake early warning. We study the application of τc*Pd for its estimation on the earthquake size using 123 events recorded by the borehole stations of KiK-net in Japan. The new type of earthquake size determined by τc*Pd is more related to the damage potential. We find that τc*Pd provides another parameter to measure the size of earthquake and the threshold to warn strong ground motion.

  3. Triggered Seismicity in Utah from the November 3, 2002, Denali Fault Earthquake

    Science.gov (United States)

    Pankow, K. L.; Nava, S. J.; Pechmann, J. C.; Arabasz, W. J.

    2002-12-01

    Coincident with the arrival of the surface waves from the November 3, 2002, Mw 7.9 Denali Fault, Alaska earthquake (DFE), the University of Utah Seismograph Stations (UUSS) regional seismic network detected a marked increase in seismicity along the Intermountain Seismic Belt (ISB) in central and north-central Utah. The number of earthquakes per day in Utah located automatically by the UUSS's Earthworm system in the week following the DFE was approximately double the long-term average during the preceding nine months. From these preliminary data, the increased seismicity appears to be characterized by small magnitude events (M = 3.2) and concentrated in five distinct spatial clusters within the ISB between 38.75°and 42.0° N. The first of these earthquakes was an M 2.2 event located ~20 km east of Salt Lake City, Utah, which occurred during the arrival of the Love waves from the DFE. The increase in Utah earthquake activity at the time of the arrival of the surface waves from the DFE suggests that these surface waves triggered earthquakes in Utah at distances of more than 3,000 km from the source. We estimated the peak dynamic shear stress caused by these surface waves from measurements of their peak vector velocities at 43 recording sites: 37 strong-motion stations of the Advanced National Seismic System and six broadband stations. (The records from six other broadband instruments in the region of interest were clipped.) The estimated peak stresses ranged from 1.2 bars to 3.5 bars with a mean of 2.3 bars, and generally occurred during the arrival of Love waves of ~15 sec period. These peak dynamic shear stress estimates are comparable to those obtained from recordings of the 1992 Mw 7.3 Landers, California, earthquake in regions where the Landers earthquake triggered increased seismicity. We plan to present more complete analyses of UUSS seismic network data, further testing our hypothesis that the DFE remotely triggered seismicity in Utah. This hypothesis is

  4. Strong-Motion Data From the Parkfield Earthquake of September 28, 2004

    Science.gov (United States)

    Shakal, A. F.; Borcherdt, R. D.; Graizer, V.; Haddadi, H.; Huang, M.; Lin, K.; Stephens, C.

    2004-12-01

    Very complex ground motion with high spatial variability was recorded in the near field of the M6 Parkfield earthquake of 9/28/04 by a strong motion array. The array provided the highest density of recording stations in the near field of any earthquake recorded to date. A total of 56 stations were located within 20 km of the fault; 48 were within 10 km of the fault, more than for many other earthquakes combined. Most (45) of the stations were part of a specialized array of classic analog instruments installed by CGS in the early 1980s, and 11 were digital high resolution instruments installed by the USGS. The set of recordings obtained provide a wealth of information on near field ground motion. Processing and analysis of the strong-motion data, available at www.cisn-edc.org, is underway. The spatial variation of the ground motion, even over relatively short distances, is great. For example, a peak acceleration of 0.30 g was recorded in the town of Parkfield, but several stations, within about 2 km, that surround this station recorded acceleration levels well over 1 g. The strong shaking at these stations, near the termination end of the rupture, is consistent with directivity focusing, as the rupture propagated from the epicenter near Gold Hill to the northwest. However, some of the strongest shaking occurs well south of the rupture, at stations near Hwy 46 at the south end of the Cholame Valley, incompatible with directivity focusing from a simple rupture. An additional aspect is that several near-fault stations have very low shaking, despite being directly over the rupturing fault. This may provide a quantitative basis to understand observed cases of low-strength buildings immediately near a fault being only slightly damaged.

  5. Earthquake effect on the geological environment

    International Nuclear Information System (INIS)

    Kawamura, Makoto

    1999-01-01

    Acceleration caused by the earthquake, changes in the water pressure, and the rock-mass strain were monitored for a series of 344 earthquakes from 1990 to 1998 at Kamaishi In Situ Test Site. The largest acceleration was registered to be 57.14 gal with the earthquake named 'North coast of Iwate Earthquake' (M4.4) occurred in June, 1996. Changes of the water pressure were recorded with 27 earthquakes; the largest change was -0.35 Kgt/cm 2 . The water-pressure change by earthquake was, however, usually smaller than that caused by rainfall in this area. No change in the electric conductivity or pH of ground water was detected before and after the earthquake throughout the entire period of monitoring. The rock-mass strain was measured with a extensometer whose detection limit was of the order of 10 -8 to 10 -9 degrees and the remaining strain of about 2.5x10 -9 degrees was detected following the 'Offshore Miyagi Earthquake' (M5.1) in October, 1997. (H. Baba)

  6. GEOS seismograms recorded for aftershocks of the earthquakes of December 7, 1988, near Spitak, Armenia SSR, during the time period 26 December 1988 14:00 through 29 December 1988 (UTC)

    Science.gov (United States)

    Borcherdt, R.D.; Glassmoyer, Gary; Cranswick, Edward

    1989-01-01

    The earthquakes of December 7, 1988, near Spitak, Armenia SSR, serve as another grim reminder of the serious hazard that earthquakes pose throughout the world. We extend our heartfelt sympathies to the families of the earthquake victims and intend that our cooperative scientific endeavours will help reduce losses in future earthquakes. Only through a better understanding of earthquake hazards can earthquake losses be reduced for all peoples in seismically active regions of the world.The tragic consequences of these earthquakes remind scientists and public officials alike of their urgent responsibilities to understand and mitigate the effects of earthquakes. On behalf of the U.S. Geological Survey, I would like to express appreciation to our Soviet colleagues for their kind invitation to participate in joint scientific and engineering studies. Without their cooperation and generous assistance, the conduct of these studies would not have been possible.This report provides seismologic and geologic data collected during the time period December 21, 1988, through February 2, 1989. These data are presented in their entirety to expedite analysis of the data set for inferences regarding hazard mitigation actions, applicable not only in Armenia but other regions of the world exposed to high seismic risk.

  7. Electron Pitch Angle Variations Recorded at the High Magnetic Latitude Boundary Layer by the NUADU Instrument on the TC-2 Spacecraft

    Science.gov (United States)

    Lu, L.; McKenna-Lawlor, S.; Barabash, S.; Liu, Z.; Balaz, J.; Brinkfeldt, K.; Strhansky, I.; Shen, C.; Shi, J.; Cao, J.; Pu, Z.; Fu, S.; Gunell, H.; Kudela, K.; Roelof, E. C.; Brandt, P. C.; Dandouras, I.; Zhang, T.; Carr, C.; Fazakerley, A.

    2005-12-01

    During the first on orbit commission, with the deflection high voltage zero, the NUADU (NeUtral Atom Detector Unit) instrument aboard TC-2, with its high temporal-spatial resolution recorded 4d solid angle images of energetic particles spiraling around the geomagnetic field lines with different configuration at high northern magnetic latitude L>10. The ambient magnetic field and particles in different energy spectrum were simultaneously measured by the magnetometer experiment (FGM), the plasma electron and current experiment (PEACE), the low energy ion detector (LEID), and the high energy electron detector (HEED). The up-flowing electron beams made the pitch angle distribution (PAD) ring like configuration, and even concentrated toward the field lines to form a dumbbell-type PAD. In integration of the variations of ambient magnetic field and particles in different energy spectrums, a temporal string magnetic bottle model was proposed which might be formed by the disturbance of the magnetic pulse. Changes in the particle pitch angle diffusion may be associated with electron acceleration along the geomagnetic field lines.

  8. Youth Actuarial Risk Assessment Tool (Y-ARAT): The development of an actuarial risk assessment instrument for predicting general offense recidivism on the basis of police records.

    Science.gov (United States)

    van der Put, Claudia E

    2014-06-01

    Estimating the risk for recidivism is important for many areas of the criminal justice system. In the present study, the Youth Actuarial Risk Assessment Tool (Y-ARAT) was developed for juvenile offenders based solely on police records, with the aim to estimate the risk of general recidivism among large groups of juvenile offenders by police officers without clinical expertise. On the basis of the Y-ARAT, juvenile offenders are classified into five risk groups based on (combinations of) 10 variables including different types of incidents in which the juvenile was a suspect, total number of incidents in which the juvenile was a suspect, total number of other incidents, total number of incidents in which co-occupants at the youth's address were suspects, gender, and age at first incident. The Y-ARAT was developed on a sample of 2,501 juvenile offenders and validated on another sample of 2,499 juvenile offenders, showing moderate predictive accuracy (area under the receiver-operating-characteristic curve = .73), with little variation between the construction and validation sample. The predictive accuracy of the Y-ARAT was considered sufficient to justify its use as a screening instrument for the police. © The Author(s) 2013.

  9. Strong motion duration and earthquake magnitude relationships

    International Nuclear Information System (INIS)

    Salmon, M.W.; Short, S.A.; Kennedy, R.P.

    1992-06-01

    Earthquake duration is the total time of ground shaking from the arrival of seismic waves until the return to ambient conditions. Much of this time is at relatively low shaking levels which have little effect on seismic structural response and on earthquake damage potential. As a result, a parameter termed ''strong motion duration'' has been defined by a number of investigators to be used for the purpose of evaluating seismic response and assessing the potential for structural damage due to earthquakes. This report presents methods for determining strong motion duration and a time history envelope function appropriate for various evaluation purposes, for earthquake magnitude and distance, and for site soil properties. There are numerous definitions of strong motion duration. For most of these definitions, empirical studies have been completed which relate duration to earthquake magnitude and distance and to site soil properties. Each of these definitions recognizes that only the portion of an earthquake record which has sufficiently high acceleration amplitude, energy content, or some other parameters significantly affects seismic response. Studies have been performed which indicate that the portion of an earthquake record in which the power (average rate of energy input) is maximum correlates most closely with potential damage to stiff nuclear power plant structures. Hence, this report will concentrate on energy based strong motion duration definitions

  10. Deterministic earthquake scenarios for the city of Sofia

    International Nuclear Information System (INIS)

    Slavov, S.; Paskaleva, I.; Kouteva, M.; Vaccari, P.; Panza, G.F.

    2002-08-01

    The city of Sofia is exposed to a high seismic risk. Macroseismic intensities in the range of VIII-X (MSK) can be expected in the city. The earthquakes, that can influence the hazard at Sofia, originate either beneath the city or are caused by seismic sources located within a radius of 40km. The city of Sofia is also prone to the remote Vrancea seismic zone in Romania, and particularly vulnerable are the long - period elements of the built environment. The high seismic risk and the lack of instrumental recordings of the regional seismicity makes the use of appropriate credible earthquake scenarios and ground motion modelling approaches for defining the seismic input for the city of Sofia necessary. Complete synthetic seismic signals, due to several earthquake scenarios, were computed along chosen geological profiles crossing the city, applying a hybrid technique, based on the modal summation technique and finite differences. The modelling takes into account simultaneously the geotechnical properties of the site, the position and geometry of the seismic source and the mechanical properties of the propagation medium. Acceleration, velocity and displacement time histories and related quantities of earthquake engineering interest (e.g. response spectra, ground motion amplification along the profiles) have been supplied. The approach applied in this study allows us to obtain the definition of the seismic input at low cost exploiting large quantities of existing data (e.g. geotechnical, geological, seismological). It may be efficiently used to estimate the ground motion for the purposes of microzonation, urban planning, retrofitting or insurance of the built environment, etc. (author)

  11. Attenuation characteristics of seismic motion based on earthquake observation records. Identification of damping factor at hard rock sites and its influences on ground stability evaluation

    International Nuclear Information System (INIS)

    Sato, Hiroaki; Kanatani, Mamoru; Ohtori, Yasuki

    2005-01-01

    In this report, we examined validity of currently available ground stability evaluation method by applying commonly used damping factor which was invariant for frequency. First, we conducted a survey of the actual conditions of damping factors, which were used in ground stability evaluation, on 10 existing nuclear power plants. As a result, we found that damping factor of 0.03(3%) was used in of 80 percent investigated plants. Next, a spectral inversion method using very fast simulated annealing was proposed for identifying damping factor and its lower limit. Here, the lower limit of damping factor means intrinsic damping factor. The developed inversion method was applied to borehole array data recorded at hard rock ground. From the inversion, it was found that intrinsic damping factor of hard rock ground distributed between about 0.03(3%) and 0.06(3%) at a depth of less than 100m, and between about 0.003(0.3%) and 0.01(1%) at a depth of more than 100m. Furthermore, we indicated that scattering damping factor with in a depth of less than 100m was in proportion to the almost -1.0 power of the frequency, and the factor in a depth of more than 100m had a peak in a frequency range from about 1.0 to 5.0 Hz. Therefore, it was recognized that commonly used damping of 0.03(3%) expressed intrinsic damping factor of shallower hard rock ground. Finally, we estimated the influences of damping factor on ground stability evaluation by 2D dynamic FEM analyses of hard rock foundation ground considering 8 slipping lines using 6 combinations of damping factor. It was demonstrated that the variation of damping factor was not so decisive on the results of ground stability evaluation. This suggests present ground stability evaluation method by applying commonly used damping factor is reasonable for hard rock sites. (author)

  12. Cyclic characteristics of earthquake time histories

    International Nuclear Information System (INIS)

    Hall, J.R. Jr; Shukla, D.K.; Kissenpfennig, J.F.

    1977-01-01

    From an engineering standpoint, an earthquake record may be characterized by a number of parameters, one of which is its 'cyclic characteristics'. The cyclic characteristics are most significant in fatigue analysis of structures and liquefaction analysis of soils where, in addition to the peak motion, cyclic buildup is significant. Whereas duration peak amplitude and response spectra for earthquakes have been studied extensively, the cyclic characteristics of earthquake records have not received an equivalent attention. Present procedures to define the cyclic characteristics are generally based upon counting the number of peaks at various amplitude ranges on a record. This paper presents a computer approach which describes a time history by an amplitude envelope and a phase curve. Using Fast Fourier Transform Techniques, an earthquake time history is represented as a projection along the x-axis of a rotating vector-the length the vector is given by the amplitude spectra-and the angle between the vector and x-axis is given by the phase curve. Thus one cycle is completed when the vector makes a full rotation. Based upon Miner's cumulative damage concept, the computer code automatically combines the cycles of various amplitudes to obtain the equivalent number of cycles of a given amplitude. To illustrate the overall results, the cyclic characteristics of several real and synthetic earthquake time histories have been studied and are presented in the paper, with the conclusion that this procedure provides a physical interpretation of the cyclic characteristics of earthquakes. (Auth.)

  13. The use of radon as an earthquake precursor

    International Nuclear Information System (INIS)

    Ramola, R.C.; Singh, M.; Sandhu, A.S.; Singh, S.; Virk, H.S.

    1990-01-01

    Radon monitoring for earthquake prediction is part of an integral approach since the discovery of coherent and time anomalous radon concentrations prior to, during and after the 1966 Tashkent earthquake. In this paper some studies of groundwater and soil gas radon content in relation to earthquake activities are reviewed. Laboratory experiments and the development of groundwater and soil gas radon monitoring systems are described. In addition, radon monitoring studies conducted at the Guru Nanak Dev University Campus since 1986 are presented in detail. During these studies some anomalous changes in radon concentration were recorded before earthquakes occurred in the region. The anomalous radon increases are independent of meteorological conditions and appear to be caused by strain changes, which precede the earthquake. Anomalous changes in radon concentration before an earthquake suggest that radon monitoring can serve as an additional technique in the earthquake prediction programme in India. (author)

  14. Fault healing and earthquake spectra from stick slip sequences in the laboratory and on active faults

    Science.gov (United States)

    McLaskey, G. C.; Glaser, S. D.; Thomas, A.; Burgmann, R.

    2011-12-01

    Repeating earthquake sequences (RES) are thought to occur on isolated patches of a fault that fail in repeated stick-slip fashion. RES enable researchers to study the effect of variations in earthquake recurrence time and the relationship between fault healing and earthquake generation. Fault healing is thought to be the physical process responsible for the 'state' variable in widely used rate- and state-dependent friction equations. We analyze RES created in laboratory stick slip experiments on a direct shear apparatus instrumented with an array of very high frequency (1KHz - 1MHz) displacement sensors. Tests are conducted on the model material polymethylmethacrylate (PMMA). While frictional properties of this glassy polymer can be characterized with the rate- and state- dependent friction laws, the rate of healing in PMMA is higher than room temperature rock. Our experiments show that in addition to a modest increase in fault strength and stress drop with increasing healing time, there are distinct spectral changes in the recorded laboratory earthquakes. Using the impact of a tiny sphere on the surface of the test specimen as a known source calibration function, we are able to remove the instrument and apparatus response from recorded signals so that the source spectrum of the laboratory earthquakes can be accurately estimated. The rupture of a fault that was allowed to heal produces a laboratory earthquake with increased high frequency content compared to one produced by a fault which has had less time to heal. These laboratory results are supported by observations of RES on the Calaveras and San Andreas faults, which show similar spectral changes when recurrence time is perturbed by a nearby large earthquake. Healing is typically attributed to a creep-like relaxation of the material which causes the true area of contact of interacting asperity populations to increase with time in a quasi-logarithmic way. The increase in high frequency seismicity shown here

  15. Seismic response analysis of an instrumented building structure

    Science.gov (United States)

    Li, H.-J.; Zhu, S.-Y.; Celebi, M.

    2003-01-01

    The Sheraton - Universal hotel, an instrumented building lying in North Hollywood, USA is selected for case study in this paper. The finite element method is used to produce a linear time - invariant structural model, and the SAP2000 program is employed for the time history analysis of the instrumented structure under the base excitation of strong motions recorded in the basement during the Northridge, California earthquake of 17 January 1994. The calculated structural responses are compared with the recorded data in both time domain and frequency domain, and the effects of structural parameters evaluation and indeterminate factors are discussed. Some features of structural response, such as the reason why the peak responses of acceleration in the ninth floor are larger than those in the sixteenth floor, are also explained.

  16. Heterogeneous rupture in the great Cascadia earthquake of 1700 inferred from coastal subsidence estimates

    Science.gov (United States)

    Wang, Pei-Ling; Engelhart, Simon E.; Wang, Kelin; Hawkes, Andrea D.; Horton, Benjamin P.; Nelson, Alan R.; Witter, Robert C.

    2013-01-01

    Past earthquake rupture models used to explain paleoseismic estimates of coastal subsidence during the great A.D. 1700 Cascadia earthquake have assumed a uniform slip distribution along the megathrust. Here we infer heterogeneous slip for the Cascadia margin in A.D. 1700 that is analogous to slip distributions during instrumentally recorded great subduction earthquakes worldwide. The assumption of uniform distribution in previous rupture models was due partly to the large uncertainties of then available paleoseismic data used to constrain the models. In this work, we use more precise estimates of subsidence in 1700 from detailed tidal microfossil studies. We develop a 3-D elastic dislocation model that allows the slip to vary both along strike and in the dip direction. Despite uncertainties in the updip and downdip slip extensions, the more precise subsidence estimates are best explained by a model with along-strike slip heterogeneity, with multiple patches of high-moment release separated by areas of low-moment release. For example, in A.D. 1700, there was very little slip near Alsea Bay, Oregon (~44.4°N), an area that coincides with a segment boundary previously suggested on the basis of gravity anomalies. A probable subducting seamount in this area may be responsible for impeding rupture during great earthquakes. Our results highlight the need for more precise, high-quality estimates of subsidence or uplift during prehistoric earthquakes from the coasts of southern British Columbia, northern Washington (north of 47°N), southernmost Oregon, and northern California (south of 43°N), where slip distributions of prehistoric earthquakes are poorly constrained.

  17. Seismic-electromagnetic precursors of Romania's Vrancea earthquakes

    International Nuclear Information System (INIS)

    Enescu, B.D.; Enescu, C.; Constantin, A. P.

    1999-01-01

    Diagrams were plotted from electromagnetic data that were recorded at Muntele Rosu Observatory during December 1996 to January 1997, and December 1997 to September 1998. The times when Vrancea earthquakes of magnitudes M ≥ 3.9 occurred within these periods are marked on the diagrams.The parameters of the earthquakes are given in a table which also includes information on the magnetic and electric anomalies (perturbations) preceding these earthquakes. The magnetic data prove that Vrancea earthquakes are preceded by magnetic perturbations that may be regarded as their short-term precursors. Perturbations, which could likewise be seen as short-term precursors of Vrancea earthquakes, are also noticed in the electric records. Still, a number of electric data do cast a doubt on their forerunning nature. Some suggestions are made in the end of the paper on how electromagnetic research should go ahead to be of use for Vrancea earthquake prediction. (authors)

  18. Remote Triggering of the Mw 6.9 Hokkaido Earthquake as a Result of the Mw 6.6 Indonesian Earthquake on September 11, 2008

    Directory of Open Access Journals (Sweden)

    Cheng-Horng Lin

    2012-01-01

    Full Text Available Only just recently, the phenomenon of earthquakes being triggered by a distant earthquake has been well established. Yet, most of the triggered earthquakes have been limited to small earthquakes (M < 3. Also, the exact triggering mechanism for earthquakes is still not clear. Here I show how one strong earthquake (Mw = 6.6 is capable of triggering another (Mw = 6.9 at a remote distance (~4750 km. On September 11, 2008, two strong earthquakes with magnitudes (Mw of 6.6 and 6.9 hit respectively in Indonesia and Japan within a short interval of ~21 minutes time. Careful examination of broadband seismograms recorded in Japan shows that the Hokkaido earthquake occurred just as the surface waves generated by the Indonesia earthquake arrived. Although the peak dynamic stress estimated at the focus of the Hokkaido earthquake was just reaching the lower bound for the capability of triggering earthquakes in general, a more plausible mechanism for triggering an earthquake might be attributed to the change of a fault property by fluid infiltration. These observations suggest that the Hokkaido earthquake was likely triggered from a remote distance by the surface waves generated from the Indonesia earthquake. If some more cases can be observed, a temporal warning of possible interaction between strong earthquakes might be concerned in the future.

  19. Geological and seismotectonic characteristics of the broader area of the October 15, 2016, earthquake (Ioannina, Greece)

    Science.gov (United States)

    Pavlides, Spyros; Ganas, Athanasios; Chatzipetros, Alexandros; Sboras, Sotiris; Valkaniotis, Sotiris; Papathanassiou, George; Thomaidou, Efi; Georgiadis, George

    2017-04-01

    This paper examines the seismotectonic setting of the moderate earthquake of October 15, 2016, Μw=5.3 (or 5.5), in the broader area of ​​Ioannina (Epirus, Greece). In this region the problem of reviewing the geological structure with new and modern methods and techniques, in relation to the geological-seismological evidence of the recent seismic sequence, is addressed. The seismic stimulation of landslides and other soil deformations is also examined. The earthquake is interpreted as indicative of a geotectonic environment of lithospheric compression, which comprises the backbone of Pindos mountain range. It starts from southern Albania and traverses western Greece, in an almost N-S direction. This is a seismically active region with a history of strong and moderate earthquakes, such as these of 1969 (Ms=5.8), 1960 (South Albania, M> 6.5, maximum intensity VIII+) and 1967 (Arta-Ioannina, M = 6.4, maximum intensity IX). The recent earthquake is associated with a known fault zone as recorded and identified in the Greek Database of Seismogenic Sources (GreDaSS, www.gredass.unife.it). Focal mechanism data indicate that the seismic fault is reverse or high-angle thrust, striking NNW-SSE and dipping to the E. The upper part of Epirus crust (brittle), which have an estimated maximum thickness of 10 km, do not show any significant seismicity. The deeper seismicity of 10-20 km, such as this of the recent earthquake, is caused by deep crustal processes with reverse - high-angle thrust faults. We suggest that the case of this earthquake is peculiar, complex and requires careful study and attention. The precise determination of the seismogenic fault and its dimensions, although not possible to be identified by direct field observations, can be assessed through the study of seismological and geodetic data (GPS, satellite images, stress transfer), as well as its seismic behavior. Field work in the broader area, in combination with instrumental data, can contribute to

  20. The Loma Prieta, California, Earthquake of October 17, 1989: Strong Ground Motion and Ground Failure

    Science.gov (United States)

    Coordinated by Holzer, Thomas L.

    1992-01-01

    Professional Paper 1551 describes the effects at the land surface caused by the Loma Prieta earthquake. These effects: include the pattern and characteristics of strong ground shaking, liquefaction of both floodplain deposits along the Pajaro and Salinas Rivers in the Monterey Bay region and sandy artificial fills along the margins of San Francisco Bay, landslides in the epicentral region, and increased stream flow. Some significant findings and their impacts were: * Strong shaking that was amplified by a factor of about two by soft soils caused damage at up to 100 kilometers (60 miles) from the epicenter. * Instrumental recordings of the ground shaking have been used to improve how building codes consider site amplification effects from soft soils. * Liquefaction at 134 locations caused $99.2 million of the total earthquake loss of $5.9 billion. Liquefaction of floodplain deposits and sandy artificial fills was similar in nature to that which occurred in the 1906 San Francisco earthquake and indicated that many areas remain susceptible to liquefaction damage in the San Francisco and Monterey Bay regions. * Landslides caused $30 million in earthquake losses, damaging at least 200 residences. Many landslides showed evidence of movement in previous earthquakes. * Recognition of the similarities between liquefaction and landslides in 1906 and 1989 and research in intervening years that established methodologies to map liquefaction and landslide hazards prompted the California legislature to pass in 1990 the Seismic Hazards Mapping Act that required the California Geological Survey to delineate regulatory zones of areas potentially susceptible to these hazards. * The earthquake caused the flow of many streams in the epicentral region to increase. Effects were noted up to 88 km from the epicenter. * Post-earthquake studies of the Marina District of San Francisco provide perhaps the most comprehensive case history of earthquake effects at a specific site developed for

  1. A Study of the Historical Earthquake Catalog and Gutenberg-richter Parameter Values of the Korean Peninsula

    International Nuclear Information System (INIS)

    Seo, Jeong Moon; Choi, In Kil; Rhee, Hyun Me

    2010-01-01

    The KIER's Korean historical earthquake catalog was revised for MMI≥VI events recorded from the years 27 A.D. to 1904. The magnitude of each event was directly determined from the criteria suggested by Seo. The criteria incorporated the damage phenomena of the Japanese historical earthquake catalog, recent seismological studies, and the results of tests performed on ancient structures in Korea. Thus, the uncertainty of the magnitudes of the Korean historical earthquakes can be reduced. Also, the Gutenberg-Richter parameter values were estimated based on the revised catalog of this study. It was determined that the magnitudes of a maximum inland and minimum offshore event were approximately 6.3 and 6.5, respectively. The Gutenberg-Richter parameter pairs of the historical earthquake catalog were estimated to be a=5.32±0.21, b=0.95±0.19, which were somewhat lower than those obtained from recent complete instrumental earthquakes. No apparent change in the Gutenberg-Richter parameter is observed for the 16 th -17 th centuries of the seismically active period

  2. Use of Ground Motion Simulations of a Historical Earthquake for the Assessment of Past and Future Urban Risks

    Science.gov (United States)

    Kentel, E.; Çelik, A.; karimzadeh Naghshineh, S.; Askan, A.

    2017-12-01

    Erzincan city located in the Eastern part of Turkey at the conjunction of three active faults is one of the most hazardous regions in the world. In addition to several historical events, this city has experienced one of the largest earthquakes during the last century: The 27 December 1939 (Ms=8.0) event. With limited knowledge of the tectonic structure by then, the city center was relocated to the North after the 1939 earthquake by almost 5km, indeed closer to the existing major strike slip fault. This decision coupled with poor construction technologies, led to severe damage during a later event that occurred on 13 March 1992 (Mw=6.6). The 1939 earthquake occurred in the pre-instrumental era in the region with no available local seismograms whereas the 1992 event was only recorded by 3 nearby stations. There are empirical isoseismal maps from both events indicating indirectly the spatial distribution of the damage. In this study, we focus on this region and present a multidisciplinary approach to discuss the different components of uncertainties involved in the assessment and mitigation of seismic risk in urban areas. For this initial attempt, ground motion simulation of the 1939 event is performed to obtain the anticipated ground motions and shaking intensities. Using these quantified results along with the spatial distribution of the observed damage, the relocation decision is assessed and suggestions are provided for future large earthquakes to minimize potential earthquake risks.

  3. Earthquakes: hydrogeochemical precursors

    Science.gov (United States)

    Ingebritsen, Steven E.; Manga, Michael

    2014-01-01

    Earthquake prediction is a long-sought goal. Changes in groundwater chemistry before earthquakes in Iceland highlight a potential hydrogeochemical precursor, but such signals must be evaluated in the context of long-term, multiparametric data sets.

  4. Exploring Earthquakes in Real-Time

    Science.gov (United States)

    Bravo, T. K.; Kafka, A. L.; Coleman, B.; Taber, J. J.

    2013-12-01

    Earthquakes capture the attention of students and inspire them to explore the Earth. Adding the ability to view and explore recordings of significant and newsworthy earthquakes in real-time makes the subject even more compelling. To address this opportunity, the Incorporated Research Institutions for Seismology (IRIS), in collaboration with Moravian College, developed ';jAmaSeis', a cross-platform application that enables students to access real-time earthquake waveform data. Students can watch as the seismic waves are recorded on their computer, and can be among the first to analyze the data from an earthquake. jAmaSeis facilitates student centered investigations of seismological concepts using either a low-cost educational seismograph or streamed data from other educational seismographs or from any seismic station that sends data to the IRIS Data Management System. After an earthquake, students can analyze the seismograms to determine characteristics of earthquakes such as time of occurrence, distance from the epicenter to the station, magnitude, and location. The software has been designed to provide graphical clues to guide students in the analysis and assist in their interpretations. Since jAmaSeis can simultaneously record up to three stations from anywhere on the planet, there are numerous opportunities for student driven investigations. For example, students can explore differences in the seismograms from different distances from an earthquake and compare waveforms from different azimuthal directions. Students can simultaneously monitor seismicity at a tectonic plate boundary and in the middle of the plate regardless of their school location. This can help students discover for themselves the ideas underlying seismic wave propagation, regional earthquake hazards, magnitude-frequency relationships, and the details of plate tectonics. The real-time nature of the data keeps the investigations dynamic, and offers students countless opportunities to explore.

  5. Normal Faulting in the 1923 Berdún Earthquake and Postorogenic Extension in the Pyrenees

    Science.gov (United States)

    Stich, Daniel; Martín, Rosa; Batlló, Josep; Macià, Ramón; Mancilla, Flor de Lis; Morales, Jose

    2018-04-01

    The 10 July 1923 earthquake near Berdún (Spain) is the largest instrumentally recorded event in the Pyrenees. We recover old analog seismograms and use 20 hand-digitized waveforms for regional moment tensor inversion. We estimate moment magnitude Mw 5.4, centroid depth of 8 km, and a pure normal faulting source with strike parallel to the mountain chain (N292°E), dip of 66° and rake of -88°. The new mechanism fits into the general predominance of normal faulting in the Pyrenees and extension inferred from Global Positioning System data. The unique location of the 1923 earthquake, near the south Pyrenean thrust front, shows that the extensional regime is not confined to the axial zone where high topography and the crustal root are located. Together with seismicity near the northern mountain front, this indicates that gravitational potential energy in the western Pyrenees is not extracted locally but induces a wide distribution of postorogenic deformation.

  6. Prediction of site specific ground motion for large earthquake

    International Nuclear Information System (INIS)

    Kamae, Katsuhiro; Irikura, Kojiro; Fukuchi, Yasunaga.

    1990-01-01

    In this paper, we apply the semi-empirical synthesis method by IRIKURA (1983, 1986) to the estimation of site specific ground motion using accelerograms observed at Kumatori in Osaka prefecture. Target earthquakes used here are a comparatively distant earthquake (Δ=95 km, M=5.6) caused by the YAMASAKI fault and a near earthquake (Δ=27 km, M=5.6). The results obtained are as follows. 1) The accelerograms from the distant earthquake (M=5.6) are synthesized using the aftershock records (M=4.3) for 1983 YAMASAKI fault earthquake whose source parameters have been obtained by other authors from the hypocentral distribution of the aftershocks. The resultant synthetic motions show a good agreement with the observed ones. 2) The synthesis for a near earthquake (M=5.6, we call this target earthquake) are made using a small earthquake which occurred in the neighborhood of the target earthquake. Here, we apply two methods for giving the parameters for synthesis. One method is to use the parameters of YAMASAKI fault earthquake which has the same magnitude as the target earthquake, and the other is to use the parameters obtained from several existing empirical formulas. The resultant synthetic motion with the former parameters shows a good agreement with the observed one, but that with the latter does not. 3) We estimate the source parameters from the source spectra of several earthquakes which have been observed in this site. Consequently we find that the small earthquakes (M<4) as Green's functions should be carefully used because the stress drops are not constant. 4) We propose that we should designate not only the magnitudes but also seismic moments of the target earthquake and the small earthquake. (J.P.N.)

  7. Stochastic strong motion generation using slip model of 21 and 22 May 1960 mega-thrust earthquakes in the main cities of Central-South Chile

    Science.gov (United States)

    Ruiz, S.; Ojeda, J.; DelCampo, F., Sr.; Pasten, C., Sr.; Otarola, C., Sr.; Silva, R., Sr.

    2017-12-01

    In May 1960 took place the most unusual seismic sequence registered instrumentally. The Mw 8.1, Concepción earthquake occurred May, 21, 1960. The aftershocks of this event apparently migrated to the south-east, and the Mw 9.5, Valdivia mega-earthquake occurred after 33 hours. The structural damage produced by both events is not larger than other earthquakes in Chile and lower than crustal earthquakes of smaller magnitude. The damage was located in the sites with shallow soil layers of low shear wave velocity (Vs). However, no seismological station recorded this sequence. For that reason, we generate synthetic acceleration times histories for strong motion in the main cities affected by these events. We use 155 points of vertical surface displacements recopiled by Plafker and Savage in 1968, and considering the observations of this authors and local residents we separated the uplift and subsidence information associated to the first earthquake Mw 8.1 and the second mega-earthquake Mw 9.5. We consider the elastic deformation propagation, assume realist lithosphere geometry, and compute a Bayesian method that maximizes the probability density a posteriori to obtain the slip distribution. Subsequently, we use a stochastic method of generation of strong motion considering the finite fault model obtained for both earthquakes. We considered the incidence angle of ray to the surface, free surface effect and energy partition for P, SV and SH waves, dynamic corner frequency and the influence of site effect. The results show that the earthquake Mw 8.1 occurred down-dip the slab, the strong motion records are similar to other Chilean earthquake like Tocopilla Mw 7.7 (2007). For the Mw 9.5 earthquake we obtain synthetic acceleration time histories with PGA values around 0.8 g in cities near to the maximum asperity or that have low velocity soil layers. This allows us to conclude that strong motion records have important influence of the shallow soil deposits. These records

  8. A comparison among observations and earthquake simulator results for the allcal2 California fault model

    Science.gov (United States)

    Tullis, Terry. E.; Richards-Dinger, Keith B.; Barall, Michael; Dieterich, James H.; Field, Edward H.; Heien, Eric M.; Kellogg, Louise; Pollitz, Fred F.; Rundle, John B.; Sachs, Michael K.; Turcotte, Donald L.; Ward, Steven N.; Yikilmaz, M. Burak

    2012-01-01

    In order to understand earthquake hazards we would ideally have a statistical description of earthquakes for tens of thousands of years. Unfortunately the ∼100‐year instrumental, several 100‐year historical, and few 1000‐year paleoseismological records are woefully inadequate to provide a statistically significant record. Physics‐based earthquake simulators can generate arbitrarily long histories of earthquakes; thus they can provide a statistically meaningful history of simulated earthquakes. The question is, how realistic are these simulated histories? This purpose of this paper is to begin to answer that question. We compare the results between different simulators and with information that is known from the limited instrumental, historic, and paleoseismological data.As expected, the results from all the simulators show that the observational record is too short to properly represent the system behavior; therefore, although tests of the simulators against the limited observations are necessary, they are not a sufficient test of the simulators’ realism. The simulators appear to pass this necessary test. In addition, the physics‐based simulators show similar behavior even though there are large differences in the methodology. This suggests that they represent realistic behavior. Different assumptions concerning the constitutive properties of the faults do result in enhanced capabilities of some simulators. However, it appears that the similar behavior of the different simulators may result from the fault‐system geometry, slip rates, and assumed strength drops, along with the shared physics of stress transfer.This paper describes the results of running four earthquake simulators that are described elsewhere in this issue of Seismological Research Letters. The simulators ALLCAL (Ward, 2012), VIRTCAL (Sachs et al., 2012), RSQSim (Richards‐Dinger and Dieterich, 2012), and ViscoSim (Pollitz, 2012) were run on our most recent all‐California fault

  9. Ionospheric earthquake precursors

    International Nuclear Information System (INIS)

    Bulachenko, A.L.; Oraevskij, V.N.; Pokhotelov, O.A.; Sorokin, V.N.; Strakhov, V.N.; Chmyrev, V.M.

    1996-01-01

    Results of experimental study on ionospheric earthquake precursors, program development on processes in the earthquake focus and physical mechanisms of formation of various type precursors are considered. Composition of experimental cosmic system for earthquake precursors monitoring is determined. 36 refs., 5 figs

  10. Children's Ideas about Earthquakes

    Science.gov (United States)

    Simsek, Canan Lacin

    2007-01-01

    Earthquake, a natural disaster, is among the fundamental problems of many countries. If people know how to protect themselves from earthquake and arrange their life styles in compliance with this, damage they will suffer will reduce to that extent. In particular, a good training regarding earthquake to be received in primary schools is considered…

  11. New geological perspectives on earthquake recurrence models

    International Nuclear Information System (INIS)

    Schwartz, D.P.

    1997-01-01

    In most areas of the world the record of historical seismicity is too short or uncertain to accurately characterize the future distribution of earthquakes of different sizes in time and space. Most faults have not ruptured once, let alone repeatedly. Ultimately, the ability to correctly forecast the magnitude, location, and probability of future earthquakes depends on how well one can quantify the past behavior of earthquake sources. Paleoseismological trenching of active faults, historical surface ruptures, liquefaction features, and shaking-induced ground deformation structures provides fundamental information on the past behavior of earthquake sources. These studies quantify (a) the timing of individual past earthquakes and fault slip rates, which lead to estimates of recurrence intervals and the development of recurrence models and (b) the amount of displacement during individual events, which allows estimates of the sizes of past earthquakes on a fault. When timing and slip per event are combined with information on fault zone geometry and structure, models that define individual rupture segments can be developed. Paleoseismicity data, in the form of timing and size of past events, provide a window into the driving mechanism of the earthquake engine--the cycle of stress build-up and release

  12. Design basis earthquakes for critical industrial facilities and their characteristics, and the Southern Hyogo prefecture earthquake, 17 January 1995

    Energy Technology Data Exchange (ETDEWEB)

    Shibata, Heki

    1998-12-01

    This paper deals with how to establish the concept of the design basis earthquake (DBE) for critical industrial facilities such as nuclear power plants in consideration of disasters such as the Southern Hyogo prefecture earthquake, the so-called Kobe earthquake in 1995. The author once discussed various DBEs at the 7th World Conference on Earthquake Engineering. At that time, the author assumed that the strongest effective PGA would be 0.7 G, and compared the values of accelerations of a structure obtained by various codes in Japan and other countries. The maximum PGA observed by an instrument at the Southern Hyogo prefecture earthquake in 1995 exceeded the previous assumption of the author, even though the results of the previous paper had been pessimistic. According to the experience of the Kobe event, the author will point out the necessity of the third earthquake S{sub s} adding to S{sub 1} and S{sub 2} of previous DBEs.

  13. Assessing the Utility of Strong Motion Data to Determine Static Ground Displacements During Great Megathrust Earthquakes: Tohoku and Iquique

    Science.gov (United States)

    Herman, M. W.; Furlong, K. P.; Hayes, G. P.; Benz, H.

    2014-12-01

    Strong motion accelerometers can record large amplitude shaking on-scale in the near-field of large earthquake ruptures; however, numerical integration of such records to determine displacement is typically unstable due to baseline changes (i.e., distortions in the zero value) that occur during strong shaking. We use datasets from the 2011 Mw 9.0 Tohoku earthquake to assess whether a relatively simple empirical correction scheme (Boore et al., 2002) can return accurate displacement waveforms useful for constraining details of the fault slip. The coseismic deformation resulting from the Tohoku earthquake was recorded by the Kiban Kyoshin network (KiK-net) of strong motion instruments as well as by a dense network of high-rate (1 Hz) GPS instruments. After baseline correcting the KiK-net records and integrating to displacement, over 85% of the KiK-net borehole instrument waveforms and over 75% of the KiK-net surface instrument waveforms match collocated 1 Hz GPS displacement time series. Most of the records that do not match the GPS-derived displacements following the baseline correction have large, systematic drifts that can be automatically identified by examining the slopes in the first 5-10 seconds of the velocity time series. We apply the same scheme to strong motion records from the 2014 Mw 8.2 Iquique earthquake. Close correspondence in both direction and amplitude between coseismic static offsets derived from the integrated strong motion time series and those predicted from a teleseismically-derived finite fault model, as well as displacement amplitudes consistent with InSAR-derived results, suggest that the correction scheme works successfully for the Iquique event. In the absence of GPS displacements, these strong motion-derived offsets provide constraints on the overall distribution of slip on the fault. In addition, the coseismic strong motion-derived displacement time series (50-100 s long) contain a near-field record of the temporal evolution of the

  14. Evidence for strong Holocene earthquake(s) in the Wabash Valley seismic zone

    International Nuclear Information System (INIS)

    Obermeier, S.

    1991-01-01

    Many small and slightly damaging earthquakes have taken place in the region of the lower Wabash River Valley of Indiana and Illinois during the 200 years of historic record. Seismologists have long suspected the Wabash Valley seismic zone to be capable of producing earthquakes much stronger than the largest of record (m b 5.8). The seismic zone contains the poorly defined Wabash Valley fault zone and also appears to contain other vaguely defined faults at depths from which the strongest earthquakes presently originate. Faults near the surface are generally covered with thick alluvium in lowlands and a veneer of loess in uplands, which make direct observations of faults difficult. Partly because of this difficulty, a search for paleoliquefaction features was begun in 1990. Conclusions of the study are as follows: (1) an earthquake much stronger than any historic earthquake struck the lower Wabash Valley between 1,500 and 7,500 years ago; (2) the epicentral region of the prehistoric strong earthquake was the Wabash Valley seismic zone; (3) apparent sites have been located where 1811-12 earthquake accelerations can be bracketed

  15. Earthquake forecasting and warning

    Energy Technology Data Exchange (ETDEWEB)

    Rikitake, T.

    1983-01-01

    This review briefly describes two other books on the same subject either written or partially written by Rikitake. In this book, the status of earthquake prediction efforts in Japan, China, the Soviet Union, and the United States are updated. An overview of some of the organizational, legal, and societal aspects of earthquake prediction in these countries is presented, and scientific findings of precursory phenomena are included. A summary of circumstances surrounding the 1975 Haicheng earthquake, the 1978 Tangshan earthquake, and the 1976 Songpan-Pingwu earthquake (all magnitudes = 7.0) in China and the 1978 Izu-Oshima earthquake in Japan is presented. This book fails to comprehensively summarize recent advances in earthquake prediction research.

  16. Preliminary report on aftershock sequence for earthquake of January 31, 1986, near Painesville, Ohio (time period: 2/1/86-2/10/86)

    Science.gov (United States)

    Borcherdt, R.D.

    1986-01-01

    A ten-station array of broad-band digital instrumentation (GEOS) was deployed by the U. S. Geological Survey with partial support provided by Electric Power Research Institute to record the aftershock sequence of the moderate (mb ~ 4.9) earthquake that occurred on January 31, 1986 (16:46:43 UTC) near Painesville, Ohio. The occurrence of the event has raised questions concerning possible contributory factors to the occurrence of the event and questions concerning the character of earthquake-induced high-frequency ground motions in the area. To aid in the timely resolution of the implications of some of these questions, this preliminary report provides copies of the ground motion time-histories and corresponding spectra for the six identified aftershocks and two events, thought to be quarry blasts, recorded as of February 10, 1986. Recording station locations and epicenter locations based on two preliminary estimates of local seismic velocity structure are provided.

  17. Crowd-Sourced Global Earthquake Early Warning

    Science.gov (United States)

    Minson, S. E.; Brooks, B. A.; Glennie, C. L.; Murray, J. R.; Langbein, J. O.; Owen, S. E.; Iannucci, B. A.; Hauser, D. L.

    2014-12-01

    Although earthquake early warning (EEW) has shown great promise for reducing loss of life and property, it has only been implemented in a few regions due, in part, to the prohibitive cost of building the required dense seismic and geodetic networks. However, many cars and consumer smartphones, tablets, laptops, and similar devices contain low-cost versions of the same sensors used for earthquake monitoring. If a workable EEW system could be implemented based on either crowd-sourced observations from consumer devices or very inexpensive networks of instruments built from consumer-quality sensors, EEW coverage could potentially be expanded worldwide. Controlled tests of several accelerometers and global navigation satellite system (GNSS) receivers typically found in consumer devices show that, while they are significantly noisier than scientific-grade instruments, they are still accurate enough to capture displacements from moderate and large magnitude earthquakes. The accuracy of these sensors varies greatly depending on the type of data collected. Raw coarse acquisition (C/A) code GPS data are relatively noisy. These observations have a surface displacement detection threshold approaching ~1 m and would thus only be useful in large Mw 8+ earthquakes. However, incorporating either satellite-based differential corrections or using a Kalman filter to combine the raw GNSS data with low-cost acceleration data (such as from a smartphone) decreases the noise dramatically. These approaches allow detection thresholds as low as 5 cm, potentially enabling accurate warnings for earthquakes as small as Mw 6.5. Simulated performance tests show that, with data contributed from only a very small fraction of the population, a crowd-sourced EEW system would be capable of warning San Francisco and San Jose of a Mw 7 rupture on California's Hayward fault and could have accurately issued both earthquake and tsunami warnings for the 2011 Mw 9 Tohoku-oki, Japan earthquake.

  18. Mexican Earthquakes and Tsunamis Catalog Reviewed

    Science.gov (United States)

    Ramirez-Herrera, M. T.; Castillo-Aja, R.

    2015-12-01

    Today the availability of information on the internet makes online catalogs very easy to access by both scholars and the public in general. The catalog in the "Significant Earthquake Database", managed by the National Center for Environmental Information (NCEI formerly NCDC), NOAA, allows access by deploying tabular and cartographic data related to earthquakes and tsunamis contained in the database. The NCEI catalog is the product of compiling previously existing catalogs, historical sources, newspapers, and scientific articles. Because NCEI catalog has a global coverage the information is not homogeneous. Existence of historical information depends on the presence of people in places where the disaster occurred, and that the permanence of the description is preserved in documents and oral tradition. In the case of instrumental data, their availability depends on the distribution and quality of seismic stations. Therefore, the availability of information for the first half of 20th century can be improved by careful analysis of the available information and by searching and resolving inconsistencies. This study shows the advances we made in upgrading and refining data for the earthquake and tsunami catalog of Mexico since 1500 CE until today, presented in the format of table and map. Data analysis allowed us to identify the following sources of error in the location of the epicenters in existing catalogs: • Incorrect coordinate entry • Place name erroneous or mistaken • Too general data that makes difficult to locate the epicenter, mainly for older earthquakes • Inconsistency of earthquakes and the tsunami occurrence: earthquake's epicenter located too far inland reported as tsunamigenic. The process of completing the catalogs directly depends on the availability of information; as new archives are opened for inspection, there are more opportunities to complete the history of large earthquakes and tsunamis in Mexico. Here, we also present new earthquake and

  19. Comparison of SISEC code simulations with earthquake data of ordinary and base-isolated buildings

    International Nuclear Information System (INIS)

    Wang, C.Y.; Gvildys, J.

    1991-01-01

    At Argonne National Laboratory (ANL), a 3-D computer program SISEC (Seismic Isolation System Evaluation Code) is being developed for simulating the system response of isolated and ordinary structures (Wang et al. 1991). This paper describes comparison of SISEC code simulations with building response data of actual earthquakes. To ensure the accuracy of analytical simulations, recorded data of full-size reinforced concrete structures located in Sendai, Japan are used in this benchmark comparison. The test structures consist of two three-story buildings, one base-isolated and the other one ordinary founded. They were constructed side by side to investigate the effect of base isolation on the acceleration response. Among 20 earthquakes observed since April 1989, complete records of three representative earthquakes, no.2, no.6, and no.17, are used for the code validation presented in this paper. Correlations of observed and calculated accelerations at all instrument locations are made. Also, relative response characteristics of ordinary and isolated building structures are investigated. (J.P.N.)

  20. Golden Gate Bridge response: a study with low-amplitude data from three earthquakes

    Science.gov (United States)

    Çelebi, Mehmet

    2012-01-01

    The dynamic response of the Golden Gate Bridge, located north of San Francisco, CA, has been studied previously using ambient vibration data and finite element models. Since permanent seismic instrumentation was installed in 1993, only small earthquakes that originated at distances varying between ~11 to 122 km have been recorded. Nonetheless, these records prompted this study of the response of the bridge to low amplitude shaking caused by three earthquakes. Compared to previous ambient vibration studies, the earthquake response data reveal a slightly higher fundamental frequency (shorter-period) for vertical vibration of the bridge deck center span (~7.7–8.3 s versus 8.2–10.6 s), and a much higher fundamental frequency (shorter period) for the transverse direction of the deck (~11.24–16.3 s versus ~18.2 s). In this study, it is also shown that these two periods are dominant apparent periods representing interaction between tower, cable, and deck.

  1. Spectral scaling of the aftershocks of the Tocopilla 2007 earthquake in northern Chile

    Science.gov (United States)

    Lancieri, M.; Madariaga, R.; Bonilla, F.

    2012-04-01

    We study the scaling of spectral properties of a set of 68 aftershocks of the 2007 November 14 Tocopilla (M 7.8) earthquake in northern Chile. These are all subduction events with similar reverse faulting focal mechanism that were recorded by a homogenous network of continuously recording strong motion instruments. The seismic moment and the corner frequency are obtained assuming that the aftershocks satisfy an inverse omega-square spectral decay; radiated energy is computed integrating the square velocity spectrum corrected for attenuation at high frequencies and for the finite bandwidth effect. Using a graphical approach, we test the scaling of seismic spectrum, and the scale invariance of the apparent stress drop with the earthquake size. To test whether the Tocopilla aftershocks scale with a single parameter, we introduce a non-dimensional number, ?, that should be constant if earthquakes are self-similar. For the Tocopilla aftershocks, Cr varies by a factor of 2. More interestingly, Cr for the aftershocks is close to 2, the value that is expected for events that are approximately modelled by a circular crack. Thus, in spite of obvious differences in waveforms, the aftershocks of the Tocopilla earthquake are self-similar. The main shock is different because its records contain large near-field waves. Finally, we investigate the scaling of energy release rate, Gc, with the slip. We estimated Gc from our previous estimates of the source parameters, assuming a simple circular crack model. We find that Gc values scale with the slip, and are in good agreement with those found by Abercrombie and Rice for the Northridge aftershocks.

  2. Feasibility study of earthquake early warning (EEW) in Hawaii

    Science.gov (United States)

    Thelen, Weston A.; Hotovec-Ellis, Alicia J.; Bodin, Paul

    2016-09-30

    when using a regional network of seismometers. Given the current network, a single-station approach provides more warning for damaging earthquakes that occur close to the station, but it would have limited benefit compared to a fully implemented ShakeAlert system. For Honolulu, for example, the single-station approach provides an advantage over ShakeAlert only for earthquakes that occur in a narrow zone extending northeast and southwest of O‘ahu. Instrumentation and alarms associated with the single-station approach are typically maintained and assessed within the target facility, and thus no outside connectivity is required. A single-station approach, then, is unlikely to help broader populations beyond the individuals at the target facility, but they have the benefit of being commercially available for relatively little cost. The USGS Hawaiian Volcano Observatory (HVO) is the Advanced National Seismic System (ANSS) regional seismic network responsible for locating and characterizing earthquakes across the State of Hawaii. During 2014 and 2015, HVO tested a network-based EEW algorithm within the current seismic network in order to assess the suitability for building a full EEW system. Using the current seismic instrumentation and processing setup at HVO, it is possible for a network approach to release an alarm a little more than 3 seconds after the earthquake is recorded on the fourth seismometer. Presently, earthquakes having M≥3 detected with the ElarmS algorithm have an average location error of approximately 4.5 km and an average magnitude error of -0.3 compared to the reviewed catalog locations from the HVO. Additional stations and upgrades to existing seismic stations would serve to improve solution precision and warning times and additional staffing would be required to provide support for a robust, network-based EEW system. For a critical facility on the Island of Hawaiʻi, such as the telescopes atop Mauna Kea, one phased approach to mitigate losses

  3. Real-time earthquake monitoring using a search engine method.

    Science.gov (United States)

    Zhang, Jie; Zhang, Haijiang; Chen, Enhong; Zheng, Yi; Kuang, Wenhuan; Zhang, Xiong

    2014-12-04

    When an earthquake occurs, seismologists want to use recorded seismograms to infer its location, magnitude and source-focal mechanism as quickly as possible. If such information could be determined immediately, timely evacuations and emergency actions could be undertaken to mitigate earthquake damage. Current advanced methods can report the initial location and magnitude of an earthquake within a few seconds, but estimating the source-focal mechanism may require minutes to hours. Here we present an earthquake search engine, similar to a web search engine, that we developed by applying a computer fast search method to a large seismogram database to find waveforms that best fit the input data. Our method is several thousand times faster than an exact search. For an Mw 5.9 earthquake on 8 March 2012 in Xinjiang, China, the search engine can infer the earthquake's parameters in <1 s after receiving the long-period surface wave data.

  4. The installation and operation of the seismic instrumentation in Korean NPPs

    International Nuclear Information System (INIS)

    Lee, Kye Hyun; Baek, Yong Lak; Chung, Yun Suk

    1994-01-01

    Including the 7 October, 1978, Hongsung earthquake, many earthquakes have occurred in our country. The Korean peninsular is no longer a safety zone against earthquakes, and there are possibilities of the damage they cause. So therefore, it is essential to verify the safety of the safety-related facilities in the event of an earthquake. If an earthquake occurs, seismic instrumentation provides information on the vibratory ground motion and resultant vibratory responses of representative safety-related structures and equipment so that an evaluation can be made immediately as to whether or not the design response spectra have been exceeded. In this paper, general descriptions of the seismic instrumentation installed in domestic NPPs will be discussed; this includes instrument type and location, the Operating Basis Earthquake (OBE) exceedance criteria, and processing and evaluation of earthquake response data, and items to be studied for further enhancement of post-earthquake evaluation techniques are presented

  5. Earthquake engineering development before and after the March 4, 1977, Vrancea, Romania earthquake

    International Nuclear Information System (INIS)

    Georgescu, E.-S.

    2002-01-01

    At 25 years since the of the Vrancea earthquake of March, 4th 1977, we can analyze in an open and critical way its impact on the evolution of earthquake engineering codes and protection policies in Romania. The earthquake (M G-R = 7.2; M w = 7.5), produced 1,570 casualties and more than 11,300 injured persons (90% of the victims in Bucharest), seismic losses were estimated at more then USD 2 billions. The 1977 earthquake represented a significant episode of XXth century in seismic zones of Romania and neighboring countries. The INCERC seismic record of March 4, 1977 put, for the first time, in evidence the spectral content of long period seismic motions of Vrancea earthquakes, the duration, the number of cycles and values of actual accelerations, with important effects of overloading upon flexible structures. The seismic coefficients k s , the spectral curve (the dynamic coefficient β r ) and the seismic zonation map, the requirements in the antiseismic design norms were drastically, changed while the microzonation maps of the time ceased to be used, and the specific Vrancea earthquake recurrence was reconsidered based on hazard studies Thus, the paper emphasises: - the existing engineering knowledge, earthquake code and zoning maps requirements until 1977 as well as seismology and structural lessons since 1977; - recent aspects of implementing of the Earthquake Code P.100/1992 and harmonization with Eurocodes, in conjunction with the specific of urban and rural seismic risk and enforcing policies on strengthening of existing buildings; - a strategic view of disaster prevention, using earthquake scenarios and loss assessments, insurance, earthquake education and training; - the need of a closer transfer of knowledge between seismologists, engineers and officials in charge with disaster prevention public policies. (author)

  6. Actions at Kashiwazaki Kariwa Nuclear Power Station after the Niigataken Chuetsu-oki earthquake

    International Nuclear Information System (INIS)

    Orita, Shuichi

    2009-01-01

    'The Niigataken Chuetsu-oki Earthquake in 2007' occurred on July 16, 2007, and seismic motions beyond those of the design basis earthquake were recorded at Kashiwazaki Kariwa nuclear power station located near the epicenter. After the earthquake, inspections and seismic response analyses have been being performed to grasp seismic induced impacts on structures, systems and components (SSCs). In addition, re-definition of design basis earthquake, upgrading, management against disasters have been also being conducted. (author)

  7. Plant data evaluation of performance confirmation test in HTTR after Tohoku-Pacific Ocean Earthquake

    International Nuclear Information System (INIS)

    Ono, Masato; Tochio, Daisuke; Shinohara, Masanori; Shimazaki, Yosuke; Yanagi, Shunki; Iigaki, Kazuhiko

    2012-03-01

    Tohoku-Pacific Ocean Earthquake occurred on March 11th 2011 and the earthquake intensity of an upper 5 on the Japanese scale was observed in Oarai town. HTTR conducted the confirmation test on cold state in order to ensure the facilities/instruments of reactor building operate normally. In this test, the plant data in the facilities/instruments start-up phase and continue steady operation phase were measured and compared with the previous operation data, and the soundness of facilities/instruments is evaluated. As a result, in after the earthquake, the facilities/instruments operate normally and the reactor cooling function of the HTTR were ensured. (author)

  8. Plant data evaluation of performance confirmation test in HTTR after Tohoku-Pacific Ocean Earthquake

    International Nuclear Information System (INIS)

    Ono, Masato; Tochio, Daisuke; Shinohara, Masanori; Shimazaki, Yosuke; Yanagi, Shunki; Iigaki, Kazuhiko

    2012-01-01

    Tohoku-Pacific Ocean Earthquake occurred on March 11th 2011 and the earthquake intensity of an upper 5 on the Japanese scale was observed in Oarai town. HTTR conducted the confirmation test on cold state in order to ensure the facilities/instruments of reactor building operate normally. In this test, the plant data in the facilities/instruments start-up phase and continue steady operation phase were measured and compared with the previous operation data, and the soundness of facilities/instruments is evaluated. As a result, in after the earthquake, the facilities/instruments operate normally and the reactor cooling function of the HTTR were ensured. (author)

  9. Excel, Earthquakes, and Moneyball: exploring Cascadia earthquake probabilities using spreadsheets and baseball analogies

    Science.gov (United States)

    Campbell, M. R.; Salditch, L.; Brooks, E. M.; Stein, S.; Spencer, B. D.

    2017-12-01

    Much recent media attention focuses on Cascadia's earthquake hazard. A widely cited magazine article starts "An earthquake will destroy a sizable portion of the coastal Northwest. The question is when." Stories include statements like "a massive earthquake is overdue", "in the next 50 years, there is a 1-in-10 chance a "really big one" will erupt," or "the odds of the big Cascadia earthquake happening in the next fifty years are roughly one in three." These lead students to ask where the quoted probabilities come from and what they mean. These probability estimates involve two primary choices: what data are used to describe when past earthquakes happened and what models are used to forecast when future earthquakes will happen. The data come from a 10,000-year record of large paleoearthquakes compiled from subsidence data on land and turbidites, offshore deposits recording submarine slope failure. Earthquakes seem to have happened in clusters of four or five events, separated by gaps. Earthquakes within a cluster occur more frequently and regularly than in the full record. Hence the next earthquake is more likely if we assume that we are in the recent cluster that started about 1700 years ago, than if we assume the cluster is over. Students can explore how changing assumptions drastically changes probability estimates using easy-to-write and display spreadsheets, like those shown below. Insight can also come from baseball analogies. The cluster issue is like deciding whether to assume that a hitter's performance in the next game is better described by his lifetime record, or by the past few games, since he may be hitting unusually well or in a slump. The other big choice is whether to assume that the probability of an earthquake is constant with time, or is small immediately after one occurs and then grows with time. This is like whether to assume that a player's performance is the same from year to year, or changes over their career. Thus saying "the chance of

  10. Encyclopedia of earthquake engineering

    CERN Document Server

    Kougioumtzoglou, Ioannis; Patelli, Edoardo; Au, Siu-Kui

    2015-01-01

    The Encyclopedia of Earthquake Engineering is designed to be the authoritative and comprehensive reference covering all major aspects of the science of earthquake engineering, specifically focusing on the interaction between earthquakes and infrastructure. The encyclopedia comprises approximately 265 contributions. Since earthquake engineering deals with the interaction between earthquake disturbances and the built infrastructure, the emphasis is on basic design processes important to both non-specialists and engineers so that readers become suitably well-informed without needing to deal with the details of specialist understanding. The content of this encyclopedia provides technically inclined and informed readers about the ways in which earthquakes can affect our infrastructure and how engineers would go about designing against, mitigating and remediating these effects. The coverage ranges from buildings, foundations, underground construction, lifelines and bridges, roads, embankments and slopes. The encycl...

  11. Experimental study of structural response to earthquakes

    International Nuclear Information System (INIS)

    Clough, R.W.; Bertero, V.V.; Bouwkamp, J.G.; Popov, E.P.

    1975-01-01

    The objectives, methods, and some of the principal results obtained from experimental studies of the behavior of structures subjected to earthquakes are described. Although such investigations are being conducted in many laboratories throughout the world, the information presented deals specifically with projects being carried out at the Earthquake Engineering Research Center (EERC) of the University of California, Berkeley. A primary purpose of these investigations is to obtain detailed information on the inelastic response mechanisms in typical structural systems so that the experimentally observed performance can be compared with computer generated analytical predictions. Only by such comparisons can the mathematical models used in dynamic nonlinear analyses be verified and improved. Two experimental procedures for investigating earthquake structural response are discussed: the earthquake simulator facility which subjects the base of the test structure to acceleration histories similar to those recorded in actual earthquakes, and systems of hydraulic rams which impose specified displacement histories on the test components, equivalent to motions developed in structures subjected to actual'quakes. The general concept and performance of the 20ft square EERC earthquake simulator is described, and the testing of a two story concrete frame building is outlined. Correlation of the experimental results with analytical predictions demonstrates that satisfactory agreement can be obtained only if the mathematical model incorporates a stiffness deterioration mechanism which simulates the cracking and other damage suffered by the structure

  12. Accounts of damage from historical earthquakes in the northeastern Caribbean to aid in the determination of their location and intensity magnitudes

    Science.gov (United States)

    Flores, Claudia H.; ten Brink, Uri S.; Bakun, William H.

    2012-01-01

    Earthquakes have been documented in the northeastern Caribbean since the arrival of Columbus to the Americas; written accounts of these felt earthquakes exist in various parts of the world. To better understand the earthquake cycle in the Caribbean, the records of earthquakes in earlier catalogs and historical documents from various archives, which are now available online, were critically examined. This report updates previous catalogs of earthquakes, in particular earthquakes in Hispaniola, to give to the public the most comprehensive documentation of earthquake damage and to further the understanding of the earthquake cycle in the northeastern Caribbean.

  13. Earthquake at 40 feet

    Science.gov (United States)

    Miller, G. J.

    1976-01-01

    The earthquake that struck the island of Guam on November 1, 1975, at 11:17 a.m had many unique aspects-not the least of which was the experience of an earthquake of 6.25 Richter magnitude while at 40 feet. My wife Bonnie, a fellow diver, Greg Guzman, and I were diving at Gabgab Beach in teh outer harbor of Apra Harbor, engaged in underwater phoyography when the earthquake struck. 

  14. Earthquakes and economic growth

    OpenAIRE

    Fisker, Peter Simonsen

    2012-01-01

    This study explores the economic consequences of earthquakes. In particular, it is investigated how exposure to earthquakes affects economic growth both across and within countries. The key result of the empirical analysis is that while there are no observable effects at the country level, earthquake exposure significantly decreases 5-year economic growth at the local level. Areas at lower stages of economic development suffer harder in terms of economic growth than richer areas. In addition,...

  15. Major earthquakes occur regularly on an isolated plate boundary fault.

    Science.gov (United States)

    Berryman, Kelvin R; Cochran, Ursula A; Clark, Kate J; Biasi, Glenn P; Langridge, Robert M; Villamor, Pilar

    2012-06-29

    The scarcity of long geological records of major earthquakes, on different types of faults, makes testing hypotheses of regular versus random or clustered earthquake recurrence behavior difficult. We provide a fault-proximal major earthquake record spanning 8000 years on the strike-slip Alpine Fault in New Zealand. Cyclic stratigraphy at Hokuri Creek suggests that the fault ruptured to the surface 24 times, and event ages yield a 0.33 coefficient of variation in recurrence interval. We associate this near-regular earthquake recurrence with a geometrically simple strike-slip fault, with high slip rate, accommodating a high proportion of plate boundary motion that works in isolation from other faults. We propose that it is valid to apply time-dependent earthquake recurrence models for seismic hazard estimation to similar faults worldwide.

  16. Instrumentation maintenance

    International Nuclear Information System (INIS)

    Mack, D.A.

    1976-09-01

    It is essential to any research activity that accurate and efficient measurements be made for the experimental parameters under consideration for each individual experiment or test. Satisfactory measurements in turn depend upon having the necessary instruments and the capability of ensuring that they are performing within their intended specifications. This latter requirement can only be achieved by providing an adequate maintenance facility, staffed with personnel competent to understand the problems associated with instrument adjustment and repair. The Instrument Repair Shop at the Lawrence Berkeley Laboratory is designed to achieve this end. The organization, staffing and operation of this system is discussed. Maintenance policy should be based on studies of (1) preventive vs. catastrophic maintenance, (2) records indicating when equipment should be replaced rather than repaired and (3) priorities established to indicate the order in which equipment should be repaired. Upon establishing a workable maintenance policy, the staff should be instructed so that they may provide appropriate scheduled preventive maintenance, calibration and corrective procedures, and emergency repairs. The education, training and experience of the maintenance staff is discussed along with the organization for an efficient operation. The layout of the various repair shops is described in the light of laboratory space and financial constraints

  17. Automatic Event Detection and Picking of P, S Seismic Phases for Earthquake Early Warning: A Case Study of the 2008 Wenchuan Earthquake

    Science.gov (United States)

    WANG, Z.; Zhao, B.

    2015-12-01

    We develop an automatic seismic phase arrival detection and picking algorithm for the impending earthquakes occurred with diverse focal mechanisms and depths. The polarization analysis of the three-component seismograms is utilized to distinguish between P and S waves through a sliding time window. When applying the short term average/long term average (STA/LTA) method to the polarized data, we also construct a new characteristics function that can sensitively reflect the changes of signals' amplitude and frequency, providing a better detection for the phase arrival. Then an improved combination method of the higher order statistics and the Akaike information criteria (AIC) picker is applied to the refined signal to lock on the arrival time with a higher degree of accuracy. We test our techniques to the aftershocks of the Ms8.0 Wenchuan earthquake, where hundreds of three-component acceleration records with magnitudes of 4.0 to 6.4 are treated. In comparison to the analyst picks, the results of the proposed detection algorithms are shown to perform well and can be applied from a single instrument within a network of stations for the large seismic events in the Earthquake Early Warning System (EEWS).

  18. Children's emotional experience two years after an earthquake: An exploration of knowledge of earthquakes and associated emotions.

    Science.gov (United States)

    Raccanello, Daniela; Burro, Roberto; Hall, Rob

    2017-01-01

    We explored whether and how the exposure to a natural disaster such as the 2012 Emilia Romagna earthquake affected the development of children's emotional competence in terms of understanding, regulating, and expressing emotions, after two years, when compared with a control group not exposed to the earthquake. We also examined the role of class level and gender. The sample included two groups of children (n = 127) attending primary school: The experimental group (n = 65) experienced the 2012 Emilia Romagna earthquake, while the control group (n = 62) did not. The data collection took place two years after the earthquake, when children were seven or ten-year-olds. Beyond assessing the children's understanding of emotions and regulating abilities with standardized instruments, we employed semi-structured interviews to explore their knowledge of earthquakes and associated emotions, and a structured task on the intensity of some target emotions. We applied Generalized Linear Mixed Models. Exposure to the earthquake did not influence the understanding and regulation of emotions. The understanding of emotions varied according to class level and gender. Knowledge of earthquakes, emotional language, and emotions associated with earthquakes were, respectively, more complex, frequent, and intense for children who had experienced the earthquake, and at increasing ages. Our data extend the generalizability of theoretical models on children's psychological functioning following disasters, such as the dose-response model and the organizational-developmental model for child resilience, and provide further knowledge on children's emotional resources related to natural disasters, as a basis for planning educational prevention programs.

  19. Earthquake geology of the Bulnay Fault (Mongolia)

    Science.gov (United States)

    Rizza, Magali; Ritz, Jean-Franciois; Prentice, Carol S.; Vassallo, Ricardo; Braucher, Regis; Larroque, Christophe; Arzhannikova, A.; Arzhanikov, S.; Mahan, Shannon; Massault, M.; Michelot, J-L.; Todbileg, M.

    2015-01-01

    The Bulnay earthquake of July 23, 1905 (Mw 8.3-8.5), in north-central Mongolia, is one of the world's largest recorded intracontinental earthquakes and one of four great earthquakes that occurred in the region during the 20th century. The 375-km-long surface rupture of the left-lateral, strike-slip, N095°E trending Bulnay Fault associated with this earthquake is remarkable for its pronounced expression across the landscape and for the size of features produced by previous earthquakes. Our field observations suggest that in many areas the width and geometry of the rupture zone is the result of repeated earthquakes; however, in those areas where it is possible to determine that the geomorphic features are the result of the 1905 surface rupture alone, the size of the features produced by this single earthquake are singular in comparison to most other historical strike-slip surface ruptures worldwide. Along the 80 km stretch, between 97.18°E and 98.33°E, the fault zone is characterized by several meters width and the mean left-lateral 1905 offset is 8.9 ± 0.6 m with two measured cumulative offsets that are twice the 1905 slip. These observations suggest that the displacement produced during the penultimate event was similar to the 1905 slip. Morphotectonic analyses carried out at three sites along the eastern part of the Bulnay fault, allow us to estimate a mean horizontal slip rate of 3.1 ± 1.7 mm/yr over the Late Pleistocene-Holocene period. In parallel, paleoseismological investigations show evidence for two earthquakes prior to the 1905 event with recurrence intervals of ~2700-4000 years.

  20. Earthquake source model using strong motion displacement

    Indian Academy of Sciences (India)

    The strong motion displacement records available during an earthquake can be treated as the response of the earth as the a structural system to unknown forces acting at unknown locations. Thus, if the part of the earth participating in ground motion is modelled as a known finite elastic medium, one can attempt to model the ...

  1. Identification of resonant earthquake ground motion

    Indian Academy of Sciences (India)

    Resonant ground motion has been observed in earthquake records measured at several parts of the world. This class of ground motion is characterized by its energy being contained in a narrow frequency band. This paper develops measures to quantify the frequency content of the ground motion using the entropy ...

  2. Lake sediments as natural seismographs: Earthquake-related deformations (seismites) in central Canadian lakes

    Science.gov (United States)

    Doughty, M.; Eyles, N.; Eyles, C. H.; Wallace, K.; Boyce, J. I.

    2014-11-01

    Central Canada experiences numerous intraplate earthquakes but their recurrence and source areas remain obscure due to shortness of the instrumental and historic records. Unconsolidated fine-grained sediments in lake basins are 'natural seismographs' with the potential to record ancient earthquakes during the last 10,000 years since the retreat of the Laurentide Ice Sheet. Many lake basins are cut into bedrock and are structurally-controlled by the same Precambrian basement structures (shear zones, terrane boundaries and other lineaments) implicated as the source of ongoing mid-plate earthquake activity. A regional seismic sub-bottom profiling of lakes Gull, Muskoka, Joseph, Rousseau, Ontario, Wanapitei, Fairbanks, Vermilion, Nipissing, Georgian Bay, Mazinaw, Simcoe, Timiskaming, Kipawa, Parry Sound and Lake of Bays, encompassing a total of more than 2000 kilometres of high-resolution track line data supplemented by multibeam and sidescan sonar survey records show a consistent sub-bottom stratigraphy of relatively-thick lowermost lateglacial facies composed of interbedded semi-transparent mass flow facies (debrites, slumps) and rhythmically-laminated silty-clays. Mass flows together with cratered ('kettled') lake floors and associated deformations reflect a dynamic ice-contact glaciolacustrine environment. Exceptionally thick mass flow successions in Lake Timiskaming along the floor of the Timiskaming Graben within the seismically-active Western Quebec Seismic Zone (WQSZ), point to a higher frequency of earthquakes and slope failure during deglaciation and rapid glacio-isostatic rebound though faulting continues into the postglacial. Lateglacial faulting, diapiric deformation and slumping of coeval lateglacial sediments is observed in Parry Sound, Lake Muskoka and Lake Joseph, which are all located above prominent Precambrian terrane boundaries. Lateglacial sediments are sharply overlain by relatively-thin rhythmically-laminated and often semi

  3. Acoustic signature of thunder from seismic records

    Science.gov (United States)

    Kappus, Mary E.; Vernon, Frank L.

    1991-06-01

    Thunder, the sound wave through the air associated with lightning, transfers sufficient energy to the ground to trigger seismometers set to record regional earthquakes. The acoustic signature recorded on seismometers, in the form of ground velocity as a function of time, contains the same type features as pressure variations recorded with microphones in air. At a seismic station in Kislovodsk, USSR, a nearly direct lightning strike caused electronic failure of borehole instruments while leaving a brief impulsive acoustic signature on the surface instruments. The peak frequency of 25-55 Hz is consistent with previously published values for cloud-to-ground lightning strikes, but spectra from this station are contaminated by very strong wind noise in this band. A thunderstorm near a similar station in Karasu triggered more than a dozen records of individual lightning strikes during a 2-hour period. The spectra for these events are fairly broadband, with peaks at low frequencies, varying from 6 to 13 Hz. The spectra were all computed by multitaper analysis, which deals appropriately with the nonstationary thunder signal. These independent measurements of low-frequency peaks corroborate the occasional occurrences in traditional microphone records, but a theory concerning the physical mechanism to account for them is still in question. Examined separately, the individual claps in each record have similar frequency distributions, discounting a need for multiple mechanisms to explain different phases of the thunder sequence. Particle motion, determined from polarization analysis of the three-component records, is predominantly vertical downward, with smaller horizontal components indicative of the direction to the lightning bolt. In three of the records the azimuth to the lightning bolt changes with time, confirming a significant horizontal component to the lightning channel itself.

  4. Earthquake magnitude estimation using the τ c and P d method for earthquake early warning systems

    Science.gov (United States)

    Jin, Xing; Zhang, Hongcai; Li, Jun; Wei, Yongxiang; Ma, Qiang

    2013-10-01

    Earthquake early warning (EEW) systems are one of the most effective ways to reduce earthquake disaster. Earthquake magnitude estimation is one of the most important and also the most difficult parts of the entire EEW system. In this paper, based on 142 earthquake events and 253 seismic records that were recorded by the KiK-net in Japan, and aftershocks of the large Wenchuan earthquake in Sichuan, we obtained earthquake magnitude estimation relationships using the τ c and P d methods. The standard variances of magnitude calculation of these two formulas are ±0.65 and ±0.56, respectively. The P d value can also be used to estimate the peak ground motion of velocity, then warning information can be released to the public rapidly, according to the estimation results. In order to insure the stability and reliability of magnitude estimation results, we propose a compatibility test according to the natures of these two parameters. The reliability of the early warning information is significantly improved though this test.

  5. RsComm User Manual. Data system for the control of continuous recording measuring instruments (monitors); RsComm brukermanual. Datasystem for kontroll av kontinuerlig registrerende maaleinstrumenter (monitorer)

    Energy Technology Data Exchange (ETDEWEB)

    Marsteen, L.

    1996-02-01

    Norwegian Institute for Air Research (NILU) has, as a part of the quality control systems, developed an automatic system of data recording. This report describes the installation and use of the RsComm software. Using RsComm and a NILU data recorder it is possible to run system tests on air quality analyzers via a telephone line. Test reports are generated. 17 figs.

  6. A Deterministic Approach to Earthquake Prediction

    Directory of Open Access Journals (Sweden)

    Vittorio Sgrigna

    2012-01-01

    Full Text Available The paper aims at giving suggestions for a deterministic approach to investigate possible earthquake prediction and warning. A fundamental contribution can come by observations and physical modeling of earthquake precursors aiming at seeing in perspective the phenomenon earthquake within the framework of a unified theory able to explain the causes of its genesis, and the dynamics, rheology, and microphysics of its preparation, occurrence, postseismic relaxation, and interseismic phases. Studies based on combined ground and space observations of earthquake precursors are essential to address the issue. Unfortunately, up to now, what is lacking is the demonstration of a causal relationship (with explained physical processes and looking for a correlation between data gathered simultaneously and continuously by space observations and ground-based measurements. In doing this, modern and/or new methods and technologies have to be adopted to try to solve the problem. Coordinated space- and ground-based observations imply available test sites on the Earth surface to correlate ground data, collected by appropriate networks of instruments, with space ones detected on board of Low-Earth-Orbit (LEO satellites. Moreover, a new strong theoretical scientific effort is necessary to try to understand the physics of the earthquake.

  7. New constraints on the magnitude of the 4 January 1907 tsunami earthquake off Sumatra, Indonesia, and its Indian Ocean-wide tsunami

    Science.gov (United States)

    Martin, S. S.; Li, L.; Okal, E.; Kanamori, H.; Morin, J.; Sieh, K.; Switzer, A.

    2017-12-01

    On 4 January 1907, an earthquake and tsunami occurred off the west coast of Sumatra, Indonesia, causing at least 2,188 fatalities. The earthquake was given an instrumental surface-wave magnitude (MS) in the range of 7.5 to 8.0 at periods of ≈40s. The tsunami it triggered was destructive on the islands of Nias and Simeulue; on the latter, this gave rise to the legend of the S'mong. This tsunami appears in records in India, Pakistan, Sri Lanka, and as far as the island of La Réunion. In relation to published seismic magnitudes for the earthquake, the tsunami was anomalously large, qualifying it as a "tsunami earthquake." Relocations using reported arrival times suggest an epicentral location near the trench. However, unusually for a tsunami earthquake the reported macroseismic intensities were higher than expected on Nias (6-7 EMS). We present a new study of this event based on macroseismic and tsunami observations culled from published literature and colonial press reports, as well as existing and newly acquired digitized or print seismograms. This multidisciplinary combination of macroseismic and seismological data with tsunami modelling has yielded new insights into this poorly understood but scientifically and societally important tsunami earthquake in the Indian Ocean. With these new data, we discriminated two large earthquakes within an hour of each other with clear differences in seismological character. The first, we interpret to be a tsunami earthquake with low levels of shaking (3-4 EMS). For this event, we estimate a seismic moment (M0) between 0.8 and 1.2 x1021 Nm (≈MW 7.9 to 8.0) based on digitized Wiechert records at Göttingen in the frequency band 6-8 mHz. These records document a regular growth of moment with period and suggest possibly larger values of M0 at even longer periods. The second earthquake caused damage on Nias (6-7 EMS). We estimate MS 6 ¾ - 7 for the second event based on seismograms from Manila, Mizusawa, and Osaka. We also

  8. Expanding Horizons in Mitigating Earthquake Related Disasters in Urban Areas: Global Development of Real-Time Seismology

    OpenAIRE

    Utkucu, Murat; Küyük, Hüseyin Serdar; Demir, İsmail Hakkı

    2016-01-01

    Abstract Real-time seismology is a newly developing alternative approach in seismology to mitigate earthquake hazard. It exploits up-to-date advances in seismic instrument technology, data acquisition, digital communications and computer systems for quickly transforming data into earthquake information in real-time to reduce earthquake losses and its impact on social and economic life in the earthquake prone densely populated urban and industrial areas.  Real-time seismology systems are not o...

  9. Evidence of Multiple Ground-rupturing Earthquakes in the Past 4000 Years along the Pasuruan Fault, East Java, Indonesia

    Science.gov (United States)

    Marliyani, G. I.; Arrowsmith, R.; Helmi, H.

    2015-12-01

    Instrumental and historical records of earthquakes, supplemented by paleoeseismic constraints can help reveal the earthquake potential of an area. The Pasuruan fault is a high angle normal fault with prominent youthful scarps cutting young deltaic sediments in the north coast of East Java, Indonesia and may pose significant hazard to the densely populated region. This fault has not been considered a significant structure, and mapped as a lineament with no sense of motion. Information regarding past earthquakes along this fault is not available. The fault is well defined both in the imagery and in the field as a ~13km long, 2-50m-high scarp. Open and filled fractures and natural exposures of the south-dipping fault plane indicate normal sense of motion. We excavated two fault-perpendicular trenches across a relay ramp identified during our surface mapping. Evidence for past earthquakes (documented in both trenches) includes upward fault termination with associated fissure fills, colluvial wedges and scarp-derived debris, folding, and angular unconformities. The ages of the events are constrained by 23 radiocarbon dates on detrital charcoal. We calibrated the dates using IntCal13 and used Oxcal to build the age model of the events. Our preliminary age model indicates that since 2006±134 B.C., there has been at least five ground rupturing earthquakes along the fault. The oldest event identified in the trench however, is not well-dated. Our modeled 95th percentile ranges of the next four earlier earthquakes (and their mean) are A.D. 1762-1850 (1806), A.D. 1646-1770 (1708), A.D. 1078-1648 (1363), and A.D. 726-1092 (909), yielding a rough recurrence rate of 302±63 yrs. These new data imply that Pasuruan fault is more active than previously thought. Additional well-dated earthquakes are necessary to build a solid earthquake recurrence model. Rupture along the whole section implies a minimum earthquake magnitude of 6.3, considering 13km as the minimum surface rupture

  10. ICIASF '85 - International Congress on Instrumentation in Aerospace Simulation Facilities, 11th, Stanford University, CA, August 26-28, 1985, Record

    Science.gov (United States)

    1985-01-01

    Developments related to laser Doppler velocimetry are discussed, taking into account a three-component dual beam laser-Doppler-anemometer to be operated in large wind tunnels, a new optical system for three-dimensional laser-Doppler-anemometry using an argon-ion and a dye laser, and a two-component laser Doppler velocimeter by switching fringe orientation. Other topics studied are concerned with facilities, instrumentation, control, hot wire/thin film measurements, optical diagnostic techniques, signal and data processing, facilities and adaptive wall test sections, data acquisition and processing, ballistic instrument systems, dynamic testing and material deformation measurements, optical flow measurements, test techniques, force measurement systems, and holography. Attention is given to nonlinear calibration of integral wind tunnel balances, a microcomputer system for real time digitized image compression, and two phase flow diagnostics in propulsion systems.

  11. 1/f and the Earthquake Problem: Scaling constraints that facilitate operational earthquake forecasting

    Science.gov (United States)

    yoder, M. R.; Rundle, J. B.; Turcotte, D. L.

    2012-12-01

    The difficulty of forecasting earthquakes can fundamentally be attributed to the self-similar, or "1/f", nature of seismic sequences. Specifically, the rate of occurrence of earthquakes is inversely proportional to their magnitude m, or more accurately to their scalar moment M. With respect to this "1/f problem," it can be argued that catalog selection (or equivalently, determining catalog constraints) constitutes the most significant challenge to seismicity based earthquake forecasting. Here, we address and introduce a potential solution to this most daunting problem. Specifically, we introduce a framework to constrain, or partition, an earthquake catalog (a study region) in order to resolve local seismicity. In particular, we combine Gutenberg-Richter (GR), rupture length, and Omori scaling with various empirical measurements to relate the size (spatial and temporal extents) of a study area (or bins within a study area) to the local earthquake magnitude potential - the magnitude of earthquake the region is expected to experience. From this, we introduce a new type of time dependent hazard map for which the tuning parameter space is nearly fully constrained. In a similar fashion, by combining various scaling relations and also by incorporating finite extents (rupture length, area, and duration) as constraints, we develop a method to estimate the Omori (temporal) and spatial aftershock decay parameters as a function of the parent earthquake's magnitude m. From this formulation, we develop an ETAS type model that overcomes many point-source limitations of contemporary ETAS. These models demonstrate promise with respect to earthquake forecasting applications. Moreover, the methods employed suggest a general framework whereby earthquake and other complex-system, 1/f type, problems can be constrained from scaling relations and finite extents.; Record-breaking hazard map of southern California, 2012-08-06. "Warm" colors indicate local acceleration (elevated hazard

  12. Ground motions from the 2015 Mw 7.8 Gorkha, Nepal, earthquake constrained by a detailed assessment of macroseismic data

    Science.gov (United States)

    Martin, Stacey; Hough, Susan E.; Hung, Charleen

    2015-01-01

    To augment limited instrumental recordings of the Mw 7.8 Gorkha, Nepal, earthquake on 25 April 2015 (Nepali calendar: 12 Baisakh 2072, Bikram Samvat), we collected 3831 detailed media and first-person accounts of macroseismic effects that include sufficiently detailed information to assign intensities. The resulting intensity map reveals the distribution of shaking within and outside of Nepal, with the key result that shaking intensities throughout the near-field region only exceeded intensity 8 on the 1998 European Macroseismic Scale (EMS-98) in rare instances. Within the Kathmandu Valley, intensities were generally 6–7 EMS. This surprising (and fortunate) result can be explained by the nature of the mainshock ground motions, which were dominated by energy at periods significantly longer than the resonant periods of vernacular structures throughout the Kathmandu Valley. Outside of the Kathmandu Valley, intensities were also generally lower than 8 EMS, but the earthquake took a heavy toll on a number of remote villages, where many especially vulnerable masonry houses collapsed catastrophically in 7–8 EMS shaking. We further reconsider intensities from the 1833 earthquake sequence and conclude that it occurred on the same fault segment as the Gorkha earthquake.

  13. Long-period effects of the Denali earthquake on water bodies in the Puget Lowland: Observations and modeling

    Science.gov (United States)

    Barberopoulou, A.; Qamar, A.; Pratt, T.L.; Steele, W.P.

    2006-01-01

    Analysis of strong-motion instrument recordings in Seattle, Washington, resulting from the 2002 Mw 7.9 Denali, Alaska, earthquake reveals that amplification in the 0.2-to 1.0-Hz frequency band is largely governed by the shallow sediments both inside and outside the sedimentary basins beneath the Puget Lowland. Sites above the deep sedimentary strata show additional seismic-wave amplification in the 0.04- to 0.2-Hz frequency range. Surface waves generated by the Mw 7.9 Denali, Alaska, earthquake of 3 November 2002 produced pronounced water waves across Washington state. The largest water waves coincided with the area of largest seismic-wave amplification underlain by the Seattle basin. In the current work, we present reports that show Lakes Union and Washington, both located on the Seattle basin, are susceptible to large water waves generated by large local earthquakes and teleseisms. A simple model of a water body is adopted to explain the generation of waves in water basins. This model provides reasonable estimates for the water-wave amplitudes in swimming pools during the Denali earthquake but appears to underestimate the waves observed in Lake Union.

  14. Earthquakes and Schools

    Science.gov (United States)

    National Clearinghouse for Educational Facilities, 2008

    2008-01-01

    Earthquakes are low-probability, high-consequence events. Though they may occur only once in the life of a school, they can have devastating, irreversible consequences. Moderate earthquakes can cause serious damage to building contents and non-structural building systems, serious injury to students and staff, and disruption of building operations.…

  15. Bam Earthquake in Iran

    CERN Multimedia

    2004-01-01

    Following their request for help from members of international organisations, the permanent Mission of the Islamic Republic of Iran has given the following bank account number, where you can donate money to help the victims of the Bam earthquake. Re: Bam earthquake 235 - UBS 311264.35L Bubenberg Platz 3001 BERN

  16. Tradable Earthquake Certificates

    NARCIS (Netherlands)

    Woerdman, Edwin; Dulleman, Minne

    2018-01-01

    This article presents a market-based idea to compensate for earthquake damage caused by the extraction of natural gas and applies it to the case of Groningen in the Netherlands. Earthquake certificates give homeowners a right to yearly compensation for both property damage and degradation of living

  17. Optimum Sea Surface Displacement and Fault Slip Distribution of the 2017 Tehuantepec Earthquake (Mw 8.2) in Mexico Estimated From Tsunami Waveforms

    Science.gov (United States)

    Gusman, Aditya Riadi; Mulia, Iyan E.; Satake, Kenji

    2018-01-01

    The 2017 Tehuantepec earthquake (Mw 8.2) was the first great normal fault event ever instrumentally recorded to occur in the Middle America Trench. The earthquake generated a tsunami with an amplitude of 1.8 m (height = 3.5 m) in Puerto Chiapas, Mexico. Tsunami waveforms recorded at coastal tide gauges and offshore buoy stations were used to estimate the optimum sea surface displacement without assuming any fault. Our optimum sea surface displacement model indicated that the maximum uplift of 0.5 m is located near the trench and the maximum subsidence of 0.8 m on the coastal side near the epicenter. We then estimated the fault slip distribution that can best explain the optimum sea surface displacement assuming 10 different fault geometries. The best model suggests that a compact region of large slip (3-6 m) extends from a depth of 30 km to 90 km, centered at a depth of 60 km.

  18. Turkish Compulsory Earthquake Insurance and "Istanbul Earthquake

    Science.gov (United States)

    Durukal, E.; Sesetyan, K.; Erdik, M.

    2009-04-01

    The city of Istanbul will likely experience substantial direct and indirect losses as a result of a future large (M=7+) earthquake with an annual probability of occurrence of about 2%. This paper dwells on the expected building losses in terms of probable maximum and average annualized losses and discusses the results from the perspective of the compulsory earthquake insurance scheme operational in the country. The TCIP system is essentially designed to operate in Turkey with sufficient penetration to enable the accumulation of funds in the pool. Today, with only 20% national penetration, and about approximately one-half of all policies in highly earthquake prone areas (one-third in Istanbul) the system exhibits signs of adverse selection, inadequate premium structure and insufficient funding. Our findings indicate that the national compulsory earthquake insurance pool in Turkey will face difficulties in covering incurring building losses in Istanbul in the occurrence of a large earthquake. The annualized earthquake losses in Istanbul are between 140-300 million. Even if we assume that the deductible is raised to 15%, the earthquake losses that need to be paid after a large earthquake in Istanbul will be at about 2.5 Billion, somewhat above the current capacity of the TCIP. Thus, a modification to the system for the insured in Istanbul (or Marmara region) is necessary. This may mean an increase in the premia and deductible rates, purchase of larger re-insurance covers and development of a claim processing system. Also, to avoid adverse selection, the penetration rates elsewhere in Turkey need to be increased substantially. A better model would be introduction of parametric insurance for Istanbul. By such a model the losses will not be indemnified, however will be directly calculated on the basis of indexed ground motion levels and damages. The immediate improvement of a parametric insurance model over the existing one will be the elimination of the claim processing

  19. Three-dimensional magnetotelluric imaging of the 1997 Kagoshima earthquake doublet, Southwest Japan

    Science.gov (United States)

    Asamori, K.; Makuuchi, A.; Umeda, K.

    2013-12-01

    The 1997 Kagoshima earthquake doublet struck on unrecognized active faults lacking clear surface expression where very few large earthquakes have occurred. Two shallow moderate earthquakes occurred in the northwestern part of Kagoshima province, on March 26 (Mw 6.1) and May 13 (Mw 6.0) in 1997, both followed by intensive aftershock sequences. Aftershock distribution of the 1997 earthquake doublet reflects complicated rupture process attributed to the geological (rheological) conditions and coupling of hydraulic pressure as well as tectonic shear stress. For advanced understanding of dynamic interactions between fluids and faulting, it is imperative to obtain three-dimensional (3-D) images of the electrical resistivity structure around the seismogenic faults. In this study, we conduct magnetotelluric (MT) soundings in and around the source region of the 1997 Kagoshima earthquake sequence and perform a 3-D inversion of wideband MT data above a depth of 30 km. MT stations were deployed around the aftershock area of the 1997 Kagoshima earthquake. All of 42 MT sites were set up in the land area. The data were collected using five component (three magnetic and two telluric components) wide-band MT instruments (Phoenix MTU-5 system) in February, 2013. The data were acquired in the frequency range from 0.000343 to 320 Hz. The recording duration ranged from 2 to 8 days. As the cultural noises severely affect the measurements, the time series analysis focused on the nocturnal data when there were fewer noise. A simultaneous remote reference measurement was carried out at the Sawauchi site (1300 km northeast of the study area). Using the remote reference technique (Gamble et al., 1979), we were able to reduce the unfavorable cultural noises. The observed apparent resistivity and phase data were inverted simultaneously using the 3-D inversion code of Sasaki (2004). In this inversion, the 3-D blocks were set up in the crust and upper mantle. These block size in the horizontal

  20. Limitation of the Predominant-Period Estimator for Earthquake Early Warning and the Initial Rupture of Earthquakes

    Science.gov (United States)

    Yamada, T.; Ide, S.

    2007-12-01

    Earthquake early warning is an important and challenging issue for the reduction of the seismic damage, especially for the mitigation of human suffering. One of the most important problems in earthquake early warning systems is how immediately we can estimate the final size of an earthquake after we observe the ground motion. It is relevant to the problem whether the initial rupture of an earthquake has some information associated with its final size. Nakamura (1988) developed the Urgent Earthquake Detection and Alarm System (UrEDAS). It calculates the predominant period of the P wave (τp) and estimates the magnitude of an earthquake immediately after the P wave arrival from the value of τpmax, or the maximum value of τp. The similar approach has been adapted by other earthquake alarm systems (e.g., Allen and Kanamori (2003)). To investigate the characteristic of the parameter τp and the effect of the length of the time window (TW) in the τpmax calculation, we analyze the high-frequency recordings of earthquakes at very close distances in the Mponeng mine in South Africa. We find that values of τpmax have upper and lower limits. For larger earthquakes whose source durations are longer than TW, the values of τpmax have an upper limit which depends on TW. On the other hand, the values for smaller earthquakes have a lower limit which is proportional to the sampling interval. For intermediate earthquakes, the values of τpmax are close to their typical source durations. These two limits and the slope for intermediate earthquakes yield an artificial final size dependence of τpmax in a wide size range. The parameter τpmax is useful for detecting large earthquakes and broadcasting earthquake early warnings. However, its dependence on the final size of earthquakes does not suggest that the earthquake rupture is deterministic. This is because τpmax does not always have a direct relation to the physical quantities of an earthquake.

  1. GEM - The Global Earthquake Model

    Science.gov (United States)

    Smolka, A.

    2009-04-01

    Over 500,000 people died in the last decade due to earthquakes and tsunamis, mostly in the developing world, where the risk is increasing due to rapid population growth. In many seismic regions, no hazard and risk models exist, and even where models do exist, they are intelligible only by experts, or available only for commercial purposes. The Global Earthquake Model (GEM) answers the need for an openly accessible risk management tool. GEM is an internationally sanctioned public private partnership initiated by the Organisation for Economic Cooperation and Development (OECD) which will establish an authoritative standard for calculating and communicating earthquake hazard and risk, and will be designed to serve as the critical instrument to support decisions and actions that reduce earthquake losses worldwide. GEM will integrate developments on the forefront of scientific and engineering knowledge of earthquakes, at global, regional and local scale. The work is organized in three modules: hazard, risk, and socio-economic impact. The hazard module calculates probabilities of earthquake occurrence and resulting shaking at any given location. The risk module calculates fatalities, injuries, and damage based on expected shaking, building vulnerability, and the distribution of population and of exposed values and facilities. The socio-economic impact module delivers tools for making educated decisions to mitigate and manage risk. GEM will be a versatile online tool, with open source code and a map-based graphical interface. The underlying data will be open wherever possible, and its modular input and output will be adapted to multiple user groups: scientists and engineers, risk managers and decision makers in the public and private sectors, and the public-at- large. GEM will be the first global model for seismic risk assessment at a national and regional scale, and aims to achieve broad scientific participation and independence. Its development will occur in a

  2. Correlation of pre-earthquake electromagnetic signals with laboratory and field rock experiments

    Directory of Open Access Journals (Sweden)

    T. Bleier

    2010-09-01

    Full Text Available Analysis of the 2007 M5.4 Alum Rock earthquake near San José California showed that magnetic pulsations were present in large numbers and with significant amplitudes during the 2 week period leading up the event. These pulsations were 1–30 s in duration, had unusual polarities (many with only positive or only negative polarities versus both polarities, and were different than other pulsations observed over 2 years of data in that the pulse sequence was sustained over a 2 week period prior to the quake, and then disappeared shortly after the quake. A search for the underlying physics process that might explain these pulses was was undertaken, and one theory (Freund, 2002 demonstrated that charge carriers were released when various types of rocks were stressed in a laboratory environment. It was also significant that the observed charge carrier generation was transient, and resulted in pulsating current patterns. In an attempt to determine if this phenomenon occurred outside of the laboratory environment, the authors scaled up the physics experiment from a relatively small rock sample in a dry laboratory setting, to a large 7 metric tonne boulder comprised of Yosemite granite. This boulder was located in a natural, humid (above ground setting at Bass Lake, Ca. The boulder was instrumented with two Zonge Engineering, Model ANT4 induction type magnetometers, two Trifield Air Ion Counters, a surface charge detector, a geophone, a Bruker Model EM27 Fourier Transform Infra Red (FTIR spectrometer with Sterling cycle cooler, and various temperature sensors. The boulder was stressed over about 8 h using expanding concrete (Bustartm, until it fractured into three major pieces. The recorded data showed surface charge build up, magnetic pulsations, impulsive air conductivity changes, and acoustical cues starting about 5 h before the boulder actually broke. These magnetic and air conductivity pulse signatures resembled both the laboratory

  3. Earthquakes, November-December 1977

    Science.gov (United States)

    Person, W.J.

    1978-01-01

    Two major earthquakes occurred in the last 2 months of the year. A magnitude 7.0 earthquake struck San Juan Province, Argentina, on November 23, causing fatalities and damage. The second major earthquake was a magnitude 7.0 in the Bonin Islands region, an unpopulated area. On December 19, Iran experienced a destructive earthquake, which killed over 500.

  4. Earthquakes, September-October 1986

    Science.gov (United States)

    Person, W.J.

    1987-01-01

    There was one great earthquake (8.0 and above) during this reporting period in the South Pacific in the Kermadec Islands. There were no major earthquakes (7.0-7.9) but earthquake-related deaths were reported in Greece and in El Salvador. There were no destrcutive earthquakes in the United States.

  5. ShakeNet: a portable wireless sensor network for instrumenting large civil structures

    Science.gov (United States)

    Kohler, Monica D.; Hao, Shuai; Mishra, Nilesh; Govindan, Ramesh; Nigbor, Robert

    2015-08-03

    We report our findings from a U.S. Geological Survey (USGS) National Earthquake Hazards Reduction Program-funded project to develop and test a wireless, portable, strong-motion network of up to 40 triaxial accelerometers for structural health monitoring. The overall goal of the project was to record ambient vibrations for several days from USGS-instrumented structures. Structural health monitoring has important applications in fields like civil engineering and the study of earthquakes. The emergence of wireless sensor networks provides a promising means to such applications. However, while most wireless sensor networks are still in the experimentation stage, very few take into consideration the realistic earthquake engineering application requirements. To collect comprehensive data for structural health monitoring for civil engineers, high-resolution vibration sensors and sufficient sampling rates should be adopted, which makes it challenging for current wireless sensor network technology in the following ways: processing capabilities, storage limit, and communication bandwidth. The wireless sensor network has to meet expectations set by wired sensor devices prevalent in the structural health monitoring community. For this project, we built and tested an application-realistic, commercially based, portable, wireless sensor network called ShakeNet for instrumentation of large civil structures, especially for buildings, bridges, or dams after earthquakes. Two to three people can deploy ShakeNet sensors within hours after an earthquake to measure the structural response of the building or bridge during aftershocks. ShakeNet involved the development of a new sensing platform (ShakeBox) running a software suite for networking, data collection, and monitoring. Deployments reported here on a tall building and a large dam were real-world tests of ShakeNet operation, and helped to refine both hardware and software. 

  6. Extending the turbidity record: making additional use of continuous data from turbidity, acoustic-Doppler, and laser diffraction instruments and suspended-sediment samples in the Colorado River in Grand Canyon

    Science.gov (United States)

    Voichick, Nicholas; Topping, David J.

    2014-01-01

    Turbidity is a measure of the scattering and absorption of light in water, which in rivers is primarily caused by particles, usually sediment, suspended in the water. Turbidity varies significantly with differences in the design of the instrument measuring turbidity, a point that is illustrated in this study by side-by-side comparisons of two different models of instruments. Turbidity also varies with changes in the physical parameters of the particles in the water, such as concentration, grain size, grain shape, and color. A turbidity instrument that is commonly used for continuous monitoring of rivers has a light source in the near-infrared range (860±30 nanometers) and a detector oriented 90 degrees from the incident light path. This type of optical turbidity instrument has a limited measurement range (depending on pathlength) that is unable to capture the high turbidity levels of rivers that carry high suspended-sediment loads. The Colorado River in Grand Canyon is one such river, in which approximately 60 percent of the range in suspended-sediment concentration during the study period had unmeasurable turbidity using this type of optical instrument. Although some optical turbidimeters using backscatter or other techniques can measure higher concentrations of suspended sediment than the models used in this study, the maximum turbidity measurable using these other turbidimeters may still be exceeded in conditions of especially high concentrations of suspended silt and clay. In Grand Canyon, the existing optical turbidity instruments remain in use in part to provide consistency over time as new techniques are investigated. As a result, during these periods of high suspended-sediment concentration, turbidity values that could not be measured with the optical turbidity instruments were instead estimated from concurrent acoustic attenuation data collected using side-looking acoustic-Doppler profiler (ADP) instruments. Extending the turbidity record to the full

  7. Borehole strain observations of very low frequency earthquakes

    Science.gov (United States)

    Hawthorne, J. C.; Ghosh, A.; Hutchinson, A. A.

    2016-12-01

    We examine the signals of very low frequency earthquakes (VLFEs) in PBO borehole strain data in central Cascadia. These MW 3.3 - 4.1 earthquakes are best observed in seismograms at periods of 20 to 50 seconds. We look for the strain they produce on timescales from about 1 to 30 minutes. First, we stack the strain produced by 13 VLFEs identified by a grid search moment tensor inversion algorithm by Ghosh et. al. (2015) and Hutchinson and Ghosh (2016), as well as several thousand VLFEs detected through template matching these events. The VLFEs are located beneath southernmost Vancouver Island and the eastern Olympic Peninsula, and are best recorded at co-located stations B005 and B007. However, even at these stations, the signal to noise in the stack is often low, and the records are difficult to interpret. Therefore we also combine data from multiple stations and VLFE locations, and simply look for increases in the strain rate at the VLFE times, as increases in strain rate would suggest an increase in the moment rate. We compare the background strain rate in the 12 hours centered on the VLFEs with the strain rate in the 10 minutes centered on the VLFEs. The 10-minute duration is chosen as a compromise that averages out some instrumental noise without introducing too much longer-period random walk noise. Our results suggest a factor of 2 increase in strain rate--and thus moment rate--during the 10-minute VLFE intervals. The increase gives an average VLFE magnitude around M 3.5, within the range of magnitudes obtained with seismology. Further analyses are currently being carried out to better understand the evolution of moment release before, during, and after the VLFEs.

  8. Sun, Moon and Earthquakes

    Science.gov (United States)

    Kolvankar, V. G.

    2013-12-01

    During a study conducted to find the effect of Earth tides on the occurrence of earthquakes, for small areas [typically 1000km X1000km] of high-seismicity regions, it was noticed that the Sun's position in terms of universal time [GMT] shows links to the sum of EMD [longitude of earthquake location - longitude of Moon's foot print on earth] and SEM [Sun-Earth-Moon angle]. This paper provides the details of this relationship after studying earthquake data for over forty high-seismicity regions of the world. It was found that over 98% of the earthquakes for these different regions, examined for the period 1973-2008, show a direct relationship between the Sun's position [GMT] and [EMD+SEM]. As the time changes from 00-24 hours, the factor [EMD+SEM] changes through 360 degree, and plotting these two variables for earthquakes from different small regions reveals a simple 45 degree straight-line relationship between them. This relationship was tested for all earthquakes and earthquake sequences for magnitude 2.0 and above. This study conclusively proves how Sun and the Moon govern all earthquakes. Fig. 12 [A+B]. The left-hand figure provides a 24-hour plot for forty consecutive days including the main event (00:58:23 on 26.12.2004, Lat.+3.30, Long+95.980, Mb 9.0, EQ count 376). The right-hand figure provides an earthquake plot for (EMD+SEM) vs GMT timings for the same data. All the 376 events including the main event faithfully follow the straight-line curve.

  9. Real-time earthquake data feasible

    Science.gov (United States)

    Bush, Susan

    Scientists agree that early warning devices and monitoring of both Hurricane Hugo and the Mt. Pinatubo volcanic eruption saved thousands of lives. What would it take to develop this sort of early warning and monitoring system for earthquake activity?Not all that much, claims a panel assigned to study the feasibility, costs, and technology needed to establish a real-time earthquake monitoring (RTEM) system. The panel, drafted by the National Academy of Science's Committee on Seismology, has presented its findings in Real-Time Earthquake Monitoring. The recently released report states that “present technology is entirely capable of recording and processing data so as to provide real-time information, enabling people to mitigate somewhat the earthquake disaster.” RTEM systems would consist of two parts—an early warning system that would give a few seconds warning before severe shaking, and immediate postquake information within minutes of the quake that would give actual measurements of the magnitude. At this time, however, this type of warning system has not been addressed at the national level for the United States and is not included in the National Earthquake Hazard Reduction Program, according to the report.

  10. Electrostatically actuated resonant switches for earthquake detection

    KAUST Repository

    Ramini, Abdallah H.

    2013-04-01

    The modeling and design of electrostatically actuated resonant switches (EARS) for earthquake and seismic applications are presented. The basic concepts are based on operating an electrically actuated resonator close to instability bands of frequency, where it is forced to collapse (pull-in) if operated within these bands. By careful tuning, the resonator can be made to enter the instability zone upon the detection of the earthquake signal, thereby pulling-in as a switch. Such a switching action can be functionalized for useful functionalities, such as shutting off gas pipelines in the case of earthquakes, or can be used to activate a network of sensors for seismic activity recording in health monitoring applications. By placing a resonator on a printed circuit board (PCB) of a natural frequency close to that of the earthquake\\'s frequency, we show significant improvement on the detection limit of the EARS lowering it considerably to less than 60% of the EARS by itself without the PCB. © 2013 IEEE.

  11. Class Room Exercises Using JMA-59-Type Seismograms for Earthquake Study at High-School Level

    Science.gov (United States)

    Okamoto, Y.; Furuta, S.; Hirota, N.

    2013-12-01

    The JMA-59-type electromagnetic seismograph was the standard seismograph for routine observations by the Japan Meteorological Agency (JMA) from the 1960's to the 1990's. Some features of those seismograms include 1) displacement wave records (electrically integrated from a velocity output by a moving-coil-type sensor), 2) ink records on paper (analog recording with time marks), 3) continuous drum recording for 12 h, and 4) lengthy operation time over several decades. However, the digital revolution in recording systems during the 1990's made these analog features obsolete, and their abundant and bulky paper-based records were stacked and sometimes disregarded in the library of every observatory. Interestingly, from an educational aspect, the disadvantages of these old-fashioned systems become highly advantageous for educational or outreach purposes. The updated digital instrument is essentially a 'black-box,' not revealing its internal mechanisms and being too fast for observing its signal processes. While the old seismometers and recording systems have been disposed of long since, stacks of analog seismograms continue to languish in observatories' back rooms. In our study, we develop some classroom exercises for studying earthquakes at the mid- to high-school level using these analog seismograms. These exercises include 1) reading the features of seismic records, 2) measuring the S-P time, 3) converting the hypocentral distance from Omori's distance formula, 4) locating the epicenter/hypocenter using the S-P times of surrounding stations, and 5) estimating earthquake magnitude using the Tsuboi's magnitude formula. For this calculation we developed a 'nomogram'--a graphical paper calculator created using a Python-based freeware tool named 'PyNomo.' We tested many seismograms and established the following rules: 1) shallow earthquakes are appropriate for using the Tsuboi's magnitude formula; 2) there is no saturation at peak amplitude; 3) seismograms make it easy to

  12. Modified-Fibonacci-Dual-Lucas method for earthquake prediction

    Science.gov (United States)

    Boucouvalas, A. C.; Gkasios, M.; Tselikas, N. T.; Drakatos, G.

    2015-06-01

    The FDL method makes use of Fibonacci, Dual and Lucas numbers and has shown considerable success in predicting earthquake events locally as well as globally. Predicting the location of the epicenter of an earthquake is one difficult challenge the other being the timing and magnitude. One technique for predicting the onset of earthquakes is the use of cycles, and the discovery of periodicity. Part of this category is the reported FDL method. The basis of the reported FDL method is the creation of FDL future dates based on the onset date of significant earthquakes. The assumption being that each occurred earthquake discontinuity can be thought of as a generating source of FDL time series The connection between past earthquakes and future earthquakes based on FDL numbers has also been reported with sample earthquakes since 1900. Using clustering methods it has been shown that significant earthquakes (conjunct Sun, Moon opposite Sun, Moon conjunct or opposite North or South Modes. In order to test improvement of the method we used all +8R earthquakes recorded since 1900, (86 earthquakes from USGS data). We have developed the FDL numbers for each of those seeds, and examined the earthquake hit rates (for a window of 3, i.e. +-1 day of target date) and for <6.5R. The successes are counted for each one of the 86 earthquake seeds and we compare the MFDL method with the FDL method. In every case we find improvement when the starting seed date is on the planetary trigger date prior to the earthquake. We observe no improvement only when a planetary trigger coincided with the earthquake date and in this case the FDL method coincides with the MFDL. Based on the MDFL method we present the prediction method capable of predicting global events or localized earthquakes and we will discuss the accuracy of the method in as far as the prediction and location parts of the method. We show example calendar style predictions for global events as well as for the Greek region using

  13. Development and Application of the Lincoln Adherence Instrument Record for Assessing Client Adherence to Advice in Dog Behavior Consultations and Success

    Directory of Open Access Journals (Sweden)

    Lisanna Lamb

    2018-03-01

    Full Text Available Adherence to the advice of medical practitioners is critical to successful treatment outcomes and has been much researched in human health, but is less well studied in the veterinary and clinical animal behavior fields. Given that the management of behavior problems often requires substantial change in established client behavior, it is likely that adherence is a substantive issue affecting success. However, little is known about the relationships between relevant factors, and there is no established way of assessing these. Therefore, the aim of this study was to develop an instrument for coding factors likely to impinge on pet owner adherence to behavior advice and validate its utility through the identification of the factors appearing to relate most closely to a successful treatment outcome in a sample population from our clinic. Potential factors affecting adherence were identified from human health and animal behavior studies, and a survey instrument developed with items matched to these factors. Forty-two dog owners who had attended the University of Lincoln Animal Behavior Clinic over a 2-year period provided data used in the analysis. The assessment of treatment outcome success by clients and clinicians was correlated, but clinicians tended to overestimate success by half a point on a 5-point scale. Eleven items relating to adherence were found to correlate with client ratings of treatment success in a univariate analysis, with three of these remaining in an ordinal logistic regression model. These three related to trust in the advice given by the clinician, concern over distress caused to the pet in the longer term and the perceived recommendation of treatment measures that had failed. By further examining the relationship between all of these factors in a hierarchical cluster analysis, we were able to postulate ways in which we might be able to improve client adherence and thus treatment success. This provides a model for the

  14. Development and Application of the Lincoln Adherence Instrument Record for Assessing Client Adherence to Advice in Dog Behavior Consultations and Success.

    Science.gov (United States)

    Lamb, Lisanna; Affenzeller, Nadja; Hewison, Lynn; McPeake, Kevin James; Zulch, Helen; Mills, Daniel S

    2018-01-01

    Adherence to the advice of medical practitioners is critical to successful treatment outcomes and has been much researched in human health, but is less well studied in the veterinary and clinical animal behavior fields. Given that the management of behavior problems often requires substantial change in established client behavior, it is likely that adherence is a substantive issue affecting success. However, little is known about the relationships between relevant factors, and there is no established way of assessing these. Therefore, the aim of this study was to develop an instrument for coding factors likely to impinge on pet owner adherence to behavior advice and validate its utility through the identification of the factors appearing to relate most closely to a successful treatment outcome in a sample population from our clinic. Potential factors affecting adherence were identified from human health and animal behavior studies, and a survey instrument developed with items matched to these factors. Forty-two dog owners who had attended the University of Lincoln Animal Behavior Clinic over a 2-year period provided data used in the analysis. The assessment of treatment outcome success by clients and clinicians was correlated, but clinicians tended to overestimate success by half a point on a 5-point scale. Eleven items relating to adherence were found to correlate with client ratings of treatment success in a univariate analysis, with three of these remaining in an ordinal logistic regression model. These three related to trust in the advice given by the clinician, concern over distress caused to the pet in the longer term and the perceived recommendation of treatment measures that had failed. By further examining the relationship between all of these factors in a hierarchical cluster analysis, we were able to postulate ways in which we might be able to improve client adherence and thus treatment success. This provides a model for the application of the instrument

  15. Global correlations between maximum magnitudes of subduction zone interface thrust earthquakes and physical parameters of subduction zones

    NARCIS (Netherlands)

    Schellart, W. P.; Rawlinson, N.

    2013-01-01

    The maximum earthquake magnitude recorded for subduction zone plate boundaries varies considerably on Earth, with some subduction zone segments producing giant subduction zone thrust earthquakes (e.g. Chile, Alaska, Sumatra-Andaman, Japan) and others producing relatively small earthquakes (e.g.

  16. Signals of ENPEMF Used in Earthquake Prediction

    Science.gov (United States)

    Hao, G.; Dong, H.; Zeng, Z.; Wu, G.; Zabrodin, S. M.

    2012-12-01

    The signals of Earth's natural pulse electromagnetic field (ENPEMF) is a combination of the abnormal crustal magnetic field pulse affected by the earthquake, the induced field of earth's endogenous magnetic field, the induced magnetic field of the exogenous variation magnetic field, geomagnetic pulsation disturbance and other energy coupling process between sun and earth. As an instantaneous disturbance of the variation field of natural geomagnetism, ENPEMF can be used to predict earthquakes. This theory was introduced by A.A Vorobyov, who expressed a hypothesis that pulses can arise not only in the atmosphere but within the Earth's crust due to processes of tectonic-to-electric energy conversion (Vorobyov, 1970; Vorobyov, 1979). The global field time scale of ENPEMF signals has specific stability. Although the wave curves may not overlap completely at different regions, the smoothed diurnal ENPEMF patterns always exhibit the same trend per month. The feature is a good reference for observing the abnormalities of the Earth's natural magnetic field in a specific region. The frequencies of the ENPEMF signals generally locate in kilo Hz range, where frequencies within 5-25 kilo Hz range can be applied to monitor earthquakes. In Wuhan, the best observation frequency is 14.5 kilo Hz. Two special devices are placed in accordance with the S-N and W-E direction. Dramatic variation from the comparison between the pulses waveform obtained from the instruments and the normal reference envelope diagram should indicate high possibility of earthquake. The proposed detection method of earthquake based on ENPEMF can improve the geodynamic monitoring effect and can enrich earthquake prediction methods. We suggest the prospective further researches are about on the exact sources composition of ENPEMF signals, the distinction between noise and useful signals, and the effect of the Earth's gravity tide and solid tidal wave. This method may also provide a promising application in

  17. Seismic Observations Indicating That the 2015 Ogasawara (Bonin) Earthquake Ruptured Beneath the 660 km Discontinuity

    Science.gov (United States)

    Kuge, Keiko

    2017-11-01

    The termination of deep earthquakes at a depth of 700 km is a key feature for understanding the physical mechanism of deep earthquakes. The 680 km deep 30 May 2015, Ogasawara (Bonin) earthquake (Mw 7.9) and its aftershocks were recorded by seismic stations at distances from 7° to 19°. Synthetic seismograms indicate that the P waveforms depend on whether the earthquake is located above or below the 660 km discontinuity. In this study, I show that broadband recordings indicate that the 2015 earthquake may have occurred below the 660 km velocity discontinuity. Recordings of the P wave from the strongest aftershock lack evidence for wave triplication expected when a subhorizontal discontinuity underlies the hypocenter. Theoretical waveforms computed with a 660 km discontinuity above the aftershock and mainshock match the observed waveforms more accurately. These observations may indicate earthquake ruptures due to mantle minerals other than olivine or strong deformation of the 660 km phase transition.

  18. Study of responses of 64-story Rincon Building to Napa, Fremont, Piedmont, San Ramon earthquakes and ambient motions

    Science.gov (United States)

    Çelebi, Mehmet; Hooper, John; Klemencic, Ron

    2017-01-01

    We analyze the recorded responses of a 64-story, instrumented, concrete core shear wall building in San Francisco, California, equipped with tuned sloshing liquid dampers (TSDs) and buckling restraining braces (BRBs). Previously, only ambient data from the 72-channel array in the building were studied (Çelebi et al. 2013). Recently, the 24 August 2014 Mw 6.0 Napa and three other earthquakes were recorded. The peak accelerations of ambient and the larger Napa earthquake responses at the basement are 0.12 cm/s/s and 5.2 cm/s/s respectively—a factor of ~42. At the 61st level, they are 0.30 cm/s/s (ambient) and 16.8 cm/s/s (Napa), respectively—a factor of ~56. Fundamental frequencies (NS ~ 0.3, EW ~ 0.27 Hz) from earthquake responses vary within an insignificant frequency band of ~0.02–0.03 Hz when compared to those from ambient data. In the absence of soil-structure interaction (SSI), these small and insignificant differences may be attributed to (1) identification errors, (2) any nonlinear behavior, and (3) shaking levels that are not large enough to activate the BRBs and TSDs to make significant shifts in frequencies and increase damping.

  19. Strong-motion observations of the M 7.8 Gorkha, Nepal, earthquake sequence and development of the N-shake strong-motion network

    Science.gov (United States)

    Dixit, Amod; Ringler, Adam; Sumy, Danielle F.; Cochran, Elizabeth S.; Hough, Susan E.; Martin, Stacey; Gibbons, Steven; Luetgert, James H.; Galetzka, John; Shrestha, Surya; Rajaure, Sudhir; McNamara, Daniel E.

    2015-01-01

    We present and describe strong-motion data observations from the 2015 M 7.8 Gorkha, Nepal, earthquake sequence collected using existing and new Quake-Catcher Network (QCN) and U.S. Geological Survey NetQuakes sensors located in the Kathmandu Valley. A comparison of QCN data with waveforms recorded by a conventional strong-motion (NetQuakes) instrument validates the QCN data. We present preliminary analysis of spectral accelerations, and peak ground acceleration and velocity for earthquakes up to M 7.3 from the QCN stations, as well as preliminary analysis of the mainshock recording from the NetQuakes station. We show that mainshock peak accelerations were lower than expected and conclude the Kathmandu Valley experienced a pervasively nonlinear response during the mainshock. Phase picks from the QCN and NetQuakes data are also used to improve aftershock locations. This study confirms the utility of QCN instruments to contribute to ground-motion investigations and aftershock response in regions where conventional instrumentation and open-access seismic data are limited. Initial pilot installations of QCN instruments in 2014 are now being expanded to create the Nepal–Shaking Hazard Assessment for Kathmandu and its Environment (N-SHAKE) network.

  20. Earthquake Ground Motion Selection

    Science.gov (United States)

    2012-05-01

    Nonlinear analyses of soils, structures, and soil-structure systems offer the potential for more accurate characterization of geotechnical and structural response under strong earthquake shaking. The increasing use of advanced performance-based desig...

  1. 1988 Spitak Earthquake Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 1988 Spitak Earthquake database is an extensive collection of geophysical and geological data, maps, charts, images and descriptive text pertaining to the...

  2. Earthquake clustering in modern seismicity and its relationship with strong historical earthquakes around Beijing, China

    Science.gov (United States)

    Wang, Jian; Main, Ian G.; Musson, Roger M. W.

    2017-11-01

    Beijing, China's capital city, is located in a typical intraplate seismic belt, with relatively high-quality instrumental catalogue data available since 1970. The Chinese historical earthquake catalogue contains six strong historical earthquakes of Ms ≥ 6 around Beijing, the earliest in 294 AD. This poses a significant potential hazard to one of the most densely populated and economically active parts of China. In some intraplate areas, persistent clusters of events associated with historical events can occur over centuries, for example, the ongoing sequence in the New Madrid zone of the eastern US. Here we will examine the evidence for such persistent clusters around Beijing. We introduce a metric known as the `seismic density index' that quantifies the degree of clustering of seismic energy release. For a given map location, this multi-dimensional index depends on the number of events, their magnitudes, and the distances to the locations of the surrounding population of earthquakes. We apply the index to modern instrumental catalogue data between 1970 and 2014, and identify six clear candidate zones. We then compare these locations to earthquake epicentre and seismic intensity data for the six largest historical earthquakes. Each candidate zone contains one of the six historical events, and the location of peak intensity is within 5 km or so of the reported epicentre in five of these cases. In one case—the great Ms 8 earthquake of 1679—the peak is closer to the area of strongest shaking (Intensity XI or more) than the reported epicentre. The present-day event rates are similar to those predicted by the modified Omori law but there is no evidence of ongoing decay in event rates. Accordingly, the index is more likely to be picking out the location of persistent weaknesses in the lithosphere. Our results imply zones of high seismic density index could be used in principle to indicate the location of unrecorded historical of palaeoseismic events, in China and

  3. The Lushan earthquake and the giant panda: impacts and conservation.

    Science.gov (United States)

    Zhang, Zejun; Yuan, Shibin; Qi, Dunwu; Zhang, Mingchun

    2014-06-01

    Earthquakes not only result in a great loss of human life and property, but also have profound effects on the Earth's biodiversity. The Lushan earthquake occurred on 20 Apr 2013, with a magnitude of 7.0 and an intensity of 9.0 degrees. A distance of 17.0 km from its epicenter to the nearest distribution site of giant pandas recorded in the Third National Survey was determined. Making use of research on the Wenchuan earthquake (with a magnitude of 8.0), which occurred approximately 5 years ago, we briefly analyze the impacts of the Lushan earthquake on giant pandas and their habitat. An earthquake may interrupt ongoing behaviors of giant pandas and may also cause injury or death. In addition, an earthquake can damage conservation facilities for pandas, and result in further habitat fragmentation and degradation. However, from a historical point of view, the impacts of human activities on giant pandas and their habitat may, in fact, far outweigh those of natural disasters such as earthquakes. Measures taken to promote habitat restoration and conservation network reconstruction in earthquake-affected areas should be based on requirements of giant pandas, not those of humans. © 2013 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

  4. Correlating precursory declines in groundwater radon with earthquake magnitude.

    Science.gov (United States)

    Kuo, T

    2014-01-01

    Both studies at the Antung hot spring in eastern Taiwan and at the Paihe spring in southern Taiwan confirm that groundwater radon can be a consistent tracer for strain changes in the crust preceding an earthquake when observed in a low-porosity fractured aquifer surrounded by a ductile formation. Recurrent anomalous declines in groundwater radon were observed at the Antung D1 monitoring well in eastern Taiwan prior to the five earthquakes of magnitude (Mw ): 6.8, 6.1, 5.9, 5.4, and 5.0 that occurred on December 10, 2003; April 1, 2006; April 15, 2006; February 17, 2008; and July 12, 2011, respectively. For earthquakes occurring on the longitudinal valley fault in eastern Taiwan, the observed radon minima decrease as the earthquake magnitude increases. The above correlation has been proven to be useful for early warning local large earthquakes. In southern Taiwan, radon anomalous declines prior to the 2010 Mw 6.3 Jiasian, 2012 Mw 5.9 Wutai, and 2012 ML 5.4 Kaohsiung earthquakes were also recorded at the Paihe spring. For earthquakes occurring on different faults in southern Taiwan, the correlation between the observed radon minima and the earthquake magnitude is not yet possible. © 2013, National Ground Water Association.

  5. Detection of Repeating Earthquakes within the Cascadia Subduction Zone Using 2013-2014 Cascadia Initiative Amphibious Network Data

    Science.gov (United States)

    Kenefic, L.; Morton, E.; Bilek, S.

    2017-12-01

    It is well known that subduction zones create the largest earthquakes in the world, like the magnitude 9.5 Chile earthquake in 1960, or the more recent 9.1 magnitude Japan earthquake in 2011, both of which are in the top five largest earthquakes ever recorded. However, off the coast of the Pacific Northwest region of the U.S., the Cascadia subduction zone (CSZ) remains relatively quiet and modern seismic instruments have not recorded earthquakes of this size in the CSZ. The last great earthquake, a magnitude 8.7-9.2, occurred in 1700 and is constrained by written reports of the resultant tsunami in Japan and dating a drowned forest in the U.S. Previous studies have suggested the margin is most likely segmented along-strike. However, variations in frictional conditions in the CSZ fault zone are not well known. Geodetic modeling indicates that the locked seismogenic zone is likely completely offshore, which may be too far from land seismometers to adequately detect related seismicity. Ocean bottom seismometers, as part of the Cascadia Initiative Amphibious Network, were installed directly above the inferred seismogenic zone, which we use to better detect small interplate seismicity. Using the subspace detection method, this study looks to find new seismogenic zone earthquakes. This subspace detection method uses multiple previously known event templates concurrently to scan through continuous seismic data. Template events that make up the subspace are chosen from events in existing catalogs that likely occurred along the plate interface. Corresponding waveforms are windowed on the nearby Cascadia Initiative ocean bottom seismometers and coastal land seismometers for scanning. Detections that are found by the scan are similar to the template waveforms based upon a predefined threshold. Detections are then visually examined to determine if an event is present. The presence of repeating event clusters can indicate persistent seismic patches, likely corresponding to

  6. Radioisotope instruments

    CERN Document Server

    Cameron, J F; Silverleaf, D J

    1971-01-01

    International Series of Monographs in Nuclear Energy, Volume 107: Radioisotope Instruments, Part 1 focuses on the design and applications of instruments based on the radiation released by radioactive substances. The book first offers information on the physical basis of radioisotope instruments; technical and economic advantages of radioisotope instruments; and radiation hazard. The manuscript then discusses commercial radioisotope instruments, including radiation sources and detectors, computing and control units, and measuring heads. The text describes the applications of radioisotop

  7. Seismogeodesy for rapid earthquake and tsunami characterization

    Science.gov (United States)

    Bock, Y.

    2016-12-01

    Rapid estimation of earthquake magnitude and fault mechanism is critical for earthquake and tsunami warning systems. Traditionally, the monitoring of earthquakes and tsunamis has been based on seismic networks for estimating earthquake magnitude and slip, and tide gauges and deep-ocean buoys for direct measurement of tsunami waves. These methods are well developed for ocean basin-wide warnings but are not timely enough to protect vulnerable populations and infrastructure from the effects of local tsunamis, where waves may arrive within 15-30 minutes of earthquake onset time. Direct measurements of displacements by GPS networks at subduction zones allow for rapid magnitude and slip estimation in the near-source region, that are not affected by instrumental limitations and magnitude saturation experienced by local seismic networks. However, GPS displacements by themselves are too noisy for strict earthquake early warning (P-wave detection). Optimally combining high-rate GPS and seismic data (in particular, accelerometers that do not clip), referred to as seismogeodesy, provides a broadband instrument that does not clip in the near field, is impervious to magnitude saturation, and provides accurate real-time static and dynamic displacements and velocities in real time. Here we describe a NASA-funded effort to integrate GPS and seismogeodetic observations as part of NOAA's Tsunami Warning Centers in Alaska and Hawaii. It consists of a series of plug-in modules that allow for a hierarchy of rapid seismogeodetic products, including automatic P-wave picking, hypocenter estimation, S-wave prediction, magnitude scaling relationships based on P-wave amplitude (Pd) and peak ground displacement (PGD), finite-source CMT solutions and fault slip models as input for tsunami warnings and models. For the NOAA/NASA project, the modules are being integrated into an existing USGS Earthworm environment, currently limited to traditional seismic data. We are focused on a network of

  8. Monitorizarea instrumentală a construcţiilor la cutremur

    Directory of Open Access Journals (Sweden)

    Ioan Constantin Praun

    2010-12-01

    Full Text Available For the constructors, monitoring has common meanings with the usual terms surveillance, follow up, control etc. of the behavior of buildings determined by their location. The scientific literature uses “monitoring of the structural status”. The analysis of the behavior of different categories of constructions in case of an earthquake and the assessment of effects presumes, in addition to a detailed visual examination of the state of constructions and recording the observed damages, a series of experimental determinations in order to know the real resistance capacity of the damaged construction, establishing the consolidation solutions. In this context, determining the own oscillation periods of a building and comparing them with the original data represent a first method to globally appreciate the variation of the rigidity of a building after earthquake solicitation. The paper specifically presents the manner of using field observation data and instrumental data within the seismic network of INCERC when associated with advanced processing. The paper underlines the need for an extended instrumentation of buildings of national interest, such that information on the behavior of some structural categories could be available in a short time interval after the occurrence of an earthquake.

  9. Prospective testing of Coulomb short-term earthquake forecasts

    Science.gov (United States)

    Jackson, D. D.; Kagan, Y. Y.; Schorlemmer, D.; Zechar, J. D.; Wang, Q.; Wong, K.

    2009-12-01

    Earthquake induced Coulomb stresses, whether static or dynamic, suddenly change the probability of future earthquakes. Models to estimate stress and the resulting seismicity changes could help to illuminate earthquake physics and guide appropriate precautionary response. But do these models have improved forecasting power compared to empirical statistical models? The best answer lies in prospective testing in which a fully specified model, with no subsequent parameter adjustments, is evaluated against future earthquakes. The Center of Study of Earthquake Predictability (CSEP) facilitates such prospective testing of earthquake forecasts, including several short term forecasts. Formulating Coulomb stress models for formal testing involves several practical problems, mostly shared with other short-term models. First, earthquake probabilities must be calculated after each “perpetrator” earthquake but before the triggered earthquakes, or “victims”. The time interval between a perpetrator and its victims may be very short, as characterized by the Omori law for aftershocks. CSEP evaluates short term models daily, and allows daily updates of the models. However, lots can happen in a day. An alternative is to test and update models on the occurrence of each earthquake over a certain magnitude. To make such updates rapidly enough and to qualify as prospective, earthquake focal mechanisms, slip distributions, stress patterns, and earthquake probabilities would have to be made by computer without human intervention. This scheme would be more appropriate for evaluating scientific ideas, but it may be less useful for practical applications than daily updates. Second, triggered earthquakes are imperfectly recorded following larger events because their seismic waves are buried in the coda of the earlier event. To solve this problem, testing methods need to allow for “censoring” of early aftershock data, and a quantitative model for detection threshold as a function of

  10. Charles Darwin's earthquake reports

    Science.gov (United States)

    Galiev, Shamil

    2010-05-01

    As it is the 200th anniversary of Darwin's birth, 2009 has also been marked as 170 years since the publication of his book Journal of Researches. During the voyage Darwin landed at Valdivia and Concepcion, Chile, just before, during, and after a great earthquake, which demolished hundreds of buildings, killing and injuring many people. Land was waved, lifted, and cracked, volcanoes awoke and giant ocean waves attacked the coast. Darwin was the first geologist to observe and describe the effects of the great earthquake during and immediately after. These effects sometimes repeated during severe earthquakes; but great earthquakes, like Chile 1835, and giant earthquakes, like Chile 1960, are rare and remain completely unpredictable. This is one of the few areas of science, where experts remain largely in the dark. Darwin suggested that the effects were a result of ‘ …the rending of strata, at a point not very deep below the surface of the earth…' and ‘…when the crust yields to the tension, caused by its gradual elevation, there is a jar at the moment of rupture, and a greater movement...'. Darwin formulated big ideas about the earth evolution and its dynamics. These ideas set the tone for the tectonic plate theory to come. However, the plate tectonics does not completely explain why earthquakes occur within plates. Darwin emphasised that there are different kinds of earthquakes ‘...I confine the foregoing observations to the earthquakes on the coast of South America, or to similar ones, which seem generally to have been accompanied by elevation of the land. But, as we know that subsidence has gone on in other quarters of the world, fissures must there have been formed, and therefore earthquakes...' (we cite the Darwin's sentences following researchspace. auckland. ac. nz/handle/2292/4474). These thoughts agree with results of the last publications (see Nature 461, 870-872; 636-639 and 462, 42-43; 87-89). About 200 years ago Darwin gave oneself airs by the

  11. GPS Analyses of the Sumatra-Andaman Earthquake

    DEFF Research Database (Denmark)

    Khan, Shfaqat Abbas; Gudmundsson, Ólafur

    2005-01-01

    The Sumatra, Indonesia, earthquake on 26 December 2004 was one of the most devastating earthquakes in history. With a magnitude of M w = 9.3 (revised based on normal-mode amplitudes by Stein and Okal, http://www.earth.northwestern.edu/people/seth/research/sumatra.html), it is the second largest...... earthquake recorded since 1900. It occurred about 100 km off the west coast of northern Sumatra, where the relatively dense Indo-Australian plate moves beneath the lighter Burma plate, resulting in stress accumulation. The average relative velocity of the two plates is about 6 cm/yr. On 26 December 2004...

  12. Discrimination between earthquakes and chemical explosions using artificial neural networks

    International Nuclear Information System (INIS)

    Kundu, Ajit; Bhadauria, Y.S.; Roy, Falguni

    2012-05-01

    An Artificial Neural Network (ANN) for discriminating between earthquakes and chemical explosions located at epicentral distances, Δ <5 deg from Gauribidanur Array (GBA) has been developed using the short period digital seismograms recorded at GBA. For training the ANN spectral amplitude ratios between P and Lg phases computed at 13 different frequencies in the frequency range of 2-8 Hz, corresponding to 20 earthquakes and 23 chemical explosions were used along with other parameters like magnitude, epicentral distance and amplitude ratios Rg/P and Rg/Lg. After training and development, the ANN has correctly identified a set of 21 test events, comprising 6 earthquakes and 15 chemical explosions. (author)

  13. Earthquake response analysis of a base isolated building

    International Nuclear Information System (INIS)

    Mazda, T.; Shiojiri, H.; Sawada, Y.; Harada, O.; Kawai, N.; Ontsuka, S.

    1989-01-01

    Recently, the seismic isolation has become one of the popular methods in the design of important structures or equipments against the earthquakes. However, it is desired to accumulate the demonstration data on reliability of seismically isolated structures and to establish the analysis methods of those structures. Based on the above recognition, the vibration tests of a base isolated building were carried out in Tsukuba Science City. After that, many earthquake records have been obtained at the building. In order to examine the validity of numerical models, earthquake response analyses have been executed by using both lumped mass model, and finite element model

  14. Psychometric validation of a new measurement instrument for time-oriented patient information in electronic medical records: A questionnaire survey of physicians.

    Science.gov (United States)

    Shibuya, Akiko; Misawa, Jimpei; Maeda, Yukihiro; Ichikawa, Rie; Kamata, Michiyo; Inoue, Ryusuke; Morimoto, Tetsuji; Nakayama, Masaharu; Hishiki, Teruyoshi; Kondo, Yoshiaki

    2017-12-01

    Time is an important element in medical data. Physicians record and store information about patients' disease progress and treatment response in electronic medical records (EMRs). Because EMRs use timestamps, physicians can identify patterns over time regarding a patient's disease and treatment (eg, laboratory values and medications). However, analyses of physicians' use and satisfaction with EMRs have focused on functionality, storage, and system operation rather than the use of time-oriented information. This study aimed to understand physicians' needs regarding time-oriented patient information in EMRs in clinical practice. The reliability and validity of the items in the questionnaire were evaluated in 87 physicians at a national university hospital. Internal consistency was satisfactory (Cronbach alpha coefficient, 0.87). Four dimensions were identified in exploratory factor analysis. Correlations between the 4 dimensions supported the construct validity of the items. Scores of time-oriented patients' medical history in the 4 dimensions showed a significant association with physician age. Based on confirmatory factor analysis, associations were significant and positive (P information in EMRs, both time-oriented treatment results followed by time-oriented team information had significant positive associations. Our study suggests that 4 specific time-oriented patient information factors in EMRs are needed by physicians. Exploring physicians' needs regarding patient-specific time-oriented information may provide a better understanding of the barriers facing the adoption and use of EMRs (eg, decision-making and practice safety concerns) and lead to better acceptance of EMRs in physicians' clinical practices. © 2017 John Wiley & Sons, Ltd.

  15. High frequency microseismic noise as possible earthquake precursor

    OpenAIRE

    Ivica Sović; Kristina Šariri; Mladen Živčić

    2013-01-01

    Before an earthquake occurs, microseismic noise in high frequency (HF) range, i.e. 2-25 Hz, is being generated during preparation process. These signals change the microseismic noise and, consequently, the spectrum of microseismic noise. Time variation of spectra recorded at the same seismological station could imply the change of the state of noise source. We propose the image moment analysis approach to objectively compare microseismic noise spectra. The result could be used for earthquake ...

  16. Nowcasting Earthquakes and Tsunamis

    Science.gov (United States)

    Rundle, J. B.; Turcotte, D. L.

    2017-12-01

    The term "nowcasting" refers to the estimation of the current uncertain state of a dynamical system, whereas "forecasting" is a calculation of probabilities of future state(s). Nowcasting is a term that originated in economics and finance, referring to the process of determining the uncertain state of the economy or market indicators such as GDP at the current time by indirect means. We have applied this idea to seismically active regions, where the goal is to determine the current state of a system of faults, and its current level of progress through the earthquake cycle (http://onlinelibrary.wiley.com/doi/10.1002/2016EA000185/full). Advantages of our nowcasting method over forecasting models include: 1) Nowcasting is simply data analysis and does not involve a model having parameters that must be fit to data; 2) We use only earthquake catalog data which generally has known errors and characteristics; and 3) We use area-based analysis rather than fault-based analysis, meaning that the methods work equally well on land and in subduction zones. To use the nowcast method to estimate how far the fault system has progressed through the "cycle" of large recurring earthquakes, we use the global catalog of earthquakes, using "small" earthquakes to determine the level of hazard from "large" earthquakes in the region. We select a "small" region in which the nowcast is to be made, and compute the statistics of a much larger region around the small region. The statistics of the large region are then applied to the small region. For an application, we can define a small region around major global cities, for example a "small" circle of radius 150 km and a depth of 100 km, as well as a "large" earthquake magnitude, for example M6.0. The region of influence of such earthquakes is roughly 150 km radius x 100 km depth, which is the reason these values were selected. We can then compute and rank the seismic risk of the world's major cities in terms of their relative seismic risk

  17. Accelerations from the September 5, 2012 (Mw=7.6) Nicoya, Costa Rica Earthquake

    Science.gov (United States)

    Simila, G. W.; Quintero, R.; Burgoa, B.; Mohammadebrahim, E.; Segura, J.

    2013-05-01

    Since 1984, the Seismic Network of the Volcanological and Seismological Observatory of Costa Rica, Universidad Nacional (OVSICORI-UNA) has been recording and registering the seismicity in Costa Rica. Before September 2012, the earthquakes registered by this seismic network in northwestern Costa Rica were moderate to small, except the Cóbano earthquake of March 25, 1990, 13:23, Mw 7.3, lat. 9.648, long. 84.913, depth 20 km; a subduction quake at the entrance of the Gulf of Nicoya and generated peak intensities in the range of MM = VIII near the epicentral area and VI-VII in the Central Valley of Costa Rica. Six years before the installation of the seismic network, OVSICORI-UNA registered two subduction earthquakes in northwestern Costa Rica, specifically on August 23, 1978, at 00:38:32 and 00:50:29 with magnitudes Mw 7.0 (HRVD), Ms 7.0 (ISC) and depths of 58 and 69 km, respectively (EHB Bulletin). On September 5, 2012, at 14:42:02.8 UTC, the seismic network OVSICORI-UNA registered another large subduction earthquake in Nicoya peninsula, northwestern Costa Rica, located 29 km south of Samara, with a depth of 21 km and magnitude Mw 7.6, lat. 9.6392, long. 85.6167. This earthquake was caused by the subduction of the Cocos plate under the Caribbean plate in northwestern Costa Rica. This earthquake was felt throughout the country and also in much of Nicaragua. The instrumental intensity map for the Nicoya earthquake indicates that the earthquake was felt with an intensity of VII-VIII in the Puntarenas and Nicoya Peninsulas, in an area between Liberia, Cañas, Puntarenas, Cabo Blanco, Carrillo, Garza, Sardinal, and Tamarindo in Guanacaste; Nicoya city being the place where the maximum reported intensity of VIII is most notable. An intensity of VIII indicates that damage estimates are moderate to severe, and intensity VII indicates that damage estimates are moderate. According to the National Emergency Commission of Costa Rica, 371 affected communities were reported; most

  18. The Damaging Effects of Earthquake Excitation on Concrete Cooling Towers

    International Nuclear Information System (INIS)

    Abedi-Nik, Farhad; Sabouri-Ghomi, Saeid

    2008-01-01

    Reinforced concrete cooling towers of hyperbolic shell configuration find widespread application in utilities engaged in the production of electric power. In design of critical civil infrastructure of this type, it is imperative to consider all the possible loading conditions that the cooling tower may experience, an important loading condition in many countries is that of the earthquake excitation, whose influence on the integrity and stability of cooling towers is profound. Previous researches have shown that the columns supporting a cooling tower are sensitive to earthquake forces, as they are heavily loaded elements that do not possess high ductility, and understanding the behavior of columns under earthquake excitation is vital in structural design because they provide the load path for the self weight of the tower shell. This paper presents the results of a finite element investigation of a representative 'dry' cooling tower, using realistic horizontal and vertical acceleration data obtained from the recent and widely-reported Tabas, Naghan and Bam earthquakes in Iran. The results of both linear and nonlinear analyses are reported in the paper, the locations of plastic hinges within the supporting columns are identified and the ramifications of the plastic hinges on the stability of the cooling tower are assessed. It is concluded that for the (typical) cooling tower configuration analyzed, the columns that are instrumental in providing a load path are influenced greatly by earthquake loading, and for the earthquake data used in this study the representative cooling tower would be rendered unstable and would collapse under the earthquake forces considered

  19. Earthquake safety program at Lawrence Livermore National Laboratory

    International Nuclear Information System (INIS)

    Freeland, G.E.

    1985-01-01

    Within three minutes on the morning of January 24, 1980, an earthquake and three aftershocks, with Richter magnitudes of 5.8, 5.1, 4.0, and 4.2, respectively, struck the Livermore Valley. Two days later, a Richter magnitude 5.4 earthquake occurred, which had its epicenter about 4 miles northwest of the Lawrence Livermore National Laboratory (LLNL). Although no one at the Lab was seriously injured, these earthquakes caused considerable damage and disruption. Masonry and concrete structures cracked and broke, trailers shifted and fell off their pedestals, office ceilings and overhead lighting fell, and bookcases overturned. The Laboratory was suddenly immersed in a site-wide program of repairing earthquake-damaged facilities, and protecting our many employees and the surrounding community from future earthquakes. Over the past five years, LLNL has spent approximately $10 million on its earthquake restoration effort for repairs and upgrades. The discussion in this paper centers upon the earthquake damage that occurred, the clean-up and restoration efforts, the seismic review of LLNL facilities, our site-specific seismic design criteria, computer-floor upgrades, ceiling-system upgrades, unique building seismic upgrades, geologic and seismologic studies, and seismic instrumentation. 10 references

  20. Is It Possible to Predict Strong Earthquakes?

    Science.gov (United States)

    Polyakov, Y. S.; Ryabinin, G. V.; Solovyeva, A. B.; Timashev, S. F.

    2015-07-01

    The possibility of earthquake prediction is one of the key open questions in modern geophysics. We propose an approach based on the analysis of common short-term candidate precursors (2 weeks to 3 months prior to strong earthquake) with the subsequent processing of brain activity signals generated in specific types of rats (kept in laboratory settings) who reportedly sense an impending earthquake a few days prior to the event. We illustrate the identification of short-term precursors using the groundwater sodium-ion concentration data in the time frame from 2010 to 2014 (a major earthquake occurred on 28 February 2013) recorded at two different sites in the southeastern part of the Kamchatka Peninsula, Russia. The candidate precursors are observed as synchronized peaks in the nonstationarity factors, introduced within the flicker-noise spectroscopy framework for signal processing, for the high-frequency component of both time series. These peaks correspond to the local reorganizations of the underlying geophysical system that are believed to precede strong earthquakes. The rodent brain activity signals are selected as potential "immediate" (up to 2 weeks) deterministic precursors because of the recent scientific reports confirming that rodents sense imminent earthquakes and the population-genetic model of K irshvink (Soc Am 90, 312-323, 2000) showing how a reliable genetic seismic escape response system may have developed over the period of several hundred million years in certain animals. The use of brain activity signals, such as electroencephalograms, in contrast to conventional abnormal animal behavior observations, enables one to apply the standard "input-sensor-response" approach to determine what input signals trigger specific seismic escape brain activity responses.

  1. High frequency, high amplitude and low energy earthquake study of nuclear power plants

    International Nuclear Information System (INIS)

    Bernero, R.M.; Lee, A.J.H.; Sobel, P.A.

    1988-01-01

    Nuclear power plants are designed for a seismic input spectrum based on U.S. acceleration time histories. However, data recorded near several earthquakes, mostly in the Eastern U.S., are richer in high frequency energy. This paper focuses on the evaluation of one of these events, i.e., the 1986 Ohio earthquake approximately 10 miles from the Perry nuclear power plant. The Perry Seismic Category I structures were reanalyzed using the in-structure recorded earthquake motions. The calculated in-structure response spectra and recorded response spectra have the same general trends, which shows the buildings are capable of responding to high frequency earthquake motion. Dynamic stresses calculated using the Ohio earthquake recorded motions are substantially lower than the design stresses. The seismic qualification of a wide sample of equipment was reassessed using the Ohio earthquake recorded motions and the margins were found to be larger than one. The 1986 Ohio earthquake was also shown to possess much lower energy content and ductility demand than the design spectra. For the Perry case, the seismic design was shown to have adequate safety margins to accommodate the 1986 Ohio earthquake, even though the design spectra were exceeded at about 20 Hz. The NRC is evaluating the need to generically modify design spectra in light of the recent high frequency recordings. (orig.)

  2. Solar and Geomagnetic Activity Variations Correlated to Italian M6+ Earthquakes Occurred in 2016

    Science.gov (United States)

    Cataldi, Gabriele; Cataldi, Daniele; Straser, Valentino

    2017-04-01

    Between August 2016 and October 2016 in Italy were recorded three strong earthquakes: M6.2 on August 2016 at 01:36:32 UTC; M6.1 on October 26, 2016 at 19:18:08 UTC and M6,6 on October 30, 2016 at 06:40:18 UTC. The authors of this study wanted to verify the existence of a correlation between these earthquakes and solar/geomagnetic activity. To confirming or not the presence of this kind of correlation, the authors analyzed the conditions of Spaceweather "near Earth" and the characteristics of the Earth's geomagnetic field in the hours that preceded the three earthquakes. The data relating to the three earthquakes were provided by the United States Geological Survey (USGS). The data on ion density used to realize the correlation study are represented by: solar wind ion density variation detected by ACE (Advanced Composition Explorer) Satellite, in orbit near the L1 Lagrange point, at 1.5 million of km from Earth, in direction of the Sun. The instrument used to perform the measurement of the solar wind ion density is the Electron, Proton, and Alpha Monitor (EPAM) instrument, equipped on the ACE Satellite. To conduct the study, the authors have taken in consideration the variation of the solar wind protons density of three different energy fractions: differential proton flux 1060-1900 keV (p/cm^2-sec-ster-MeV); differential proton flux 761-1220 keV (p/cm^2-sec-ster-MeV); differential proton flux 310-580 keV (p/cm^2-sec-ster-MeV). Geomagnetic activity data were provided by Tromsø Geomagnetic Observatory (TGO), Norway; by Scoresbysund Geomagnetic Observatory (SCO), Greenland, Denmark; Dikson Geomagnetic Observatory (DIK), Russia and by Pushkov Institute of terrestrial magnetism, ionosphere and radio wave propagation (IZMIRAN), Troitsk, Moscow Region. The results of the study, in agreement with what already ascertained by authors from 2012, have confirmed that the three strong Italian earthquakes were preceded by a clear increase of the solar wind proton density which

  3. Electron pitch angle variations recorded at the high magnetic latitude boundary layer by the NUADU instrument on the TC-2 spacecraft

    Directory of Open Access Journals (Sweden)

    L. Lu

    2005-11-01

    Full Text Available The NUADU (NeUtral Atom Detector Unit experiment aboard TC-2 recorded, with high temporal and spatial resolution, 4π solid angle images of electrons (~50-125 keV spiraling around geomagnetic field lines at high northern magnetic latitudes (L>10, during its in-orbit commissioning phase (September 2004. The ambient magnetic field, as well as electrons in other energy ranges, were simultaneously measured by the TC-2 magnetometer (FGM, the plasma electron and current experiment (PEACE, the low energy ion detector (LEID and the high energy electron detector (HEED. The NUADU data showed that up-flowing electron beams could form "ring-like" and "dumbbell-type" pitch angle distributions (PADs in the region sampled. Changes in these pitch angle distributions due to transient magnetic variations are suggested to have been associated with electron acceleration along the geomagnetic field lines. A nested magnetic bottle configuration that formed due to the propagation towards the Earth of a magnetic pulse, is proposed to have been associated with this process.

  4. Indoor radon and earthquake

    International Nuclear Information System (INIS)

    Saghatelyan, E.; Petrosyan, L.; Aghbalyan, Yu.; Baburyan, M.; Araratyan, L.

    2004-01-01

    For the first time on the basis of the Spitak earthquake of December 1988 (Armenia, December 1988) experience it is found out that the earthquake causes intensive and prolonged radon splashes which, rapidly dispersing in the open space of close-to-earth atmosphere, are contrastingly displayed in covered premises (dwellings, schools, kindergartens) even if they are at considerable distance from the earthquake epicenter, and this multiplies the radiation influence on the population. The interval of splashes includes the period from the first fore-shock to the last after-shock, i.e. several months. The area affected by radiation is larger vs. Armenia's territory. The scale of this impact on population is 12 times higher than the number of people injured in Spitak, Leninakan and other settlements (toll of injured - 25 000 people, radiation-induced diseases in people - over 300 000). The influence of radiation directly correlates with the earthquake force. Such a conclusion is underpinned by indoor radon monitoring data for Yerevan since 1987 (120 km from epicenter) 5450 measurements and multivariate analysis with identification of cause-and-effect linkages between geo dynamics of indoor radon under stable and conditions of Earth crust, behavior of radon in different geological mediums during earthquakes, levels of room radon concentrations and effective equivalent dose of radiation impact of radiation dose on health and statistical data on public health provided by the Ministry of Health. The following hitherto unexplained facts can be considered as consequences of prolonged radiation influence on human organism: long-lasting state of apathy and indifference typical of the population of Armenia during the period of more than a year after the earthquake, prevalence of malignant cancer forms in disaster zones, dominating lung cancer and so on. All urban territories of seismically active regions are exposed to the threat of natural earthquake-provoked radiation influence

  5. The Kresna earthquake of 1904 in Bulgaria

    Energy Technology Data Exchange (ETDEWEB)

    Ambraseys, N. [Imperial College of Science, London (United Kingdom). Technology and Medicine, Dept. of Civil Engineering

    2001-02-01

    The Kresna earthquake in 1904 in Bulgaria is one of the largest shallow 20th century events on land in the Balkans. This event, which was preceded by a large foreshock, has hitherto been assigned a range of magnitudes up to M{sub s} = 7.8 but the reappraisal of instrumental data yields as much smaller value of M{sub s} = 7.2 and a re-assesment of the intensity distribution suggests 7.1. Thus both instrumental and macroseismic data appear consistent with a magnitude which is also compatible with the fault segmentation and local morphology of the region which cannot accommodate shallow events much larger than about 7.0. The relatively large size of the main shock suggests surface faulting but the available field evidence is insufficient to establish the dimensions, attitude and amount of dislocation, except perhaps in the vicinity of Krupnik. This down sizing of the Kresna earthquake has important consequences for tectonics and earthquake hazard estimates in the Balkans.

  6. The Kresna earthquake of 1904 in Bulgaria

    Directory of Open Access Journals (Sweden)

    N. N. Ambraseys

    2001-06-01

    Full Text Available The Kresna earthquake in 1904 in Bulgaria is one of the largest shallow 20th century events on land in the Balkans. This event, which was preceded by a large foreshock, has hitherto been assigned a range of magnitudes up to M S = 7.8 but the reappraisal of instrumental data yields a much smaller value of M S = 7.2 and a re-assement of the intensity distribution suggests 7.1. Thus both instrumental and macroseismic data appear consistent with a magnitude which is also compatible with the fault segmentation and local morphology of the region which cannot accommodate shallow events much larger than about 7.0. The relatively large size of the main shock suggests surface faulting but the available field evidence is insufficient to establish the dimensions, attitude andamount of dislocation, except perhaps in the vicinity of Krupnik. This downsizing of the Kresna earthquake has important consequences for tectonics and earthquake hazard estimates in the Balkans.

  7. Hysteresis behavior of seismic isolators in earthquakes near a fault ...

    African Journals Online (AJOL)

    Seismic performance and appropriate design of structures located near the faults has always been a major concern of design engineers. Because during an earthquake; the effects of plasticity will make differences in characteristics of near field records. These pulsed movements at the beginning of records will increase the ...

  8. Nucleation process and dynamic inversion of the Mw 6.9 Valparaíso 2017 earthquake in Central Chile

    Science.gov (United States)

    Ruiz, S.; Aden-Antoniow, F.; Baez, J. C., Sr.; Otarola, C., Sr.; Potin, B.; DelCampo, F., Sr.; Poli, P.; Flores, C.; Satriano, C.; Felipe, L., Sr.; Madariaga, R. I.

    2017-12-01

    The Valparaiso 2017 sequence occurred in mega-thrust Central Chile, an active zone where the last mega-earthquake occurred in 1730. An intense seismicity occurred 2 days before of the Mw 6.9 main-shock. A slow trench ward movement observed in the coastal GPS antennas accompanied the foreshock seismicity. Following the Mw 6.9 earthquake the seismicity migrated 30 Km to South-East. This sequence was well recorded by multi-parametric stations composed by GPS, Broad-Band and Strong Motion instruments. We built a seismic catalogue with 2329 events associated to Valparaiso sequence, with a magnitude completeness of Ml 2.8. We located all the seismicity considering a new 3D velocity model obtained for the Valparaiso zone, and compute the moment tensor for events with magnitude larger than Ml 3.5, and finally studied the presence of repeating earthquakes. The main-shock is studied by performing a dynamic inversion using the strong motion records and an elliptical patch approach to characterize the rupture process. During the two days nucleation stage, we observe a compact zone of repeater events. In the meantime a westward GPS movement was recorded in the coastal GPS stations. The aseismic moment estimated from GPS is larger than the foreshocks cumulative moment, suggesting the presence of a slow slip event, which potentially triggered the 6.9 mainshock. The Mw 6.9 earthquake is associated to rupture of an elliptical asperity of semi-axis of 10 km and 5 km, with a sub-shear rupture, stress drop of 11.71 MPa, yield stress of 17.21 MPa, slip weakening of 0.65 m and kappa value of 1.70. This sequence occurs close to, and with some similar characteristics that 1985 Valparaíso Mw 8.0 earthquake. The rupture of this asperity could stress more the highly locked Central Chile zone where a mega-thrust earthquake like 1730 is expected.

  9. Seismotectonic framework of the 2010 February 27 Mw 8.8 Maule, Chile earthquake sequence

    Science.gov (United States)

    Hayes, Gavin P.; Bergman, Eric; Johnson, Kendra J.; Benz, Harley M.; Brown, Lucy; Meltzer, Anne S.

    2013-01-01

    After the 2010 Mw 8.8 Maule earthquake, an international collaboration involving teams and instruments from Chile, the US, the UK, France and Germany established the International Maule Aftershock Deployment temporary network over the source region of the event to facilitate detailed, open-access studies of the aftershock sequence. Using data from the first 9-months of this deployment, we have analyzed the detailed spatial distribution of over 2500 well-recorded aftershocks. All earthquakes have been relocated using a hypocentral decomposition algorithm to study the details of and uncertainties in both their relative and absolute locations. We have computed regional moment tensor solutions for the largest of these events to produce a catalogue of 465 mechanisms, and have used all of these data to study the spatial distribution of the aftershock sequence with respect to the Chilean megathrust. We refine models of co-seismic slip distribution of the Maule earthquake, and show how small changes in fault geometries assumed in teleseismic finite fault modelling significantly improve fits to regional GPS data, implying that the accuracy of rapid teleseismic fault models can be substantially improved by consideration of existing fault geometry model databases. We interpret all of these data in an integrated seismotectonic framework for the Maule earthquake rupture and its aftershock sequence, and discuss the relationships between co-seismic rupture and aftershock distributions. While the majority of aftershocks are interplate thrust events located away from regions of maximum co-seismic slip, interesting clusters of aftershocks are identified in the lower plate at both ends of the main shock rupture, implying internal deformation of the slab in response to large slip on the plate boundary interface. We also perform Coulomb stress transfer calculations to compare aftershock locations and mechanisms to static stress changes following the Maule rupture. Without the

  10. Acceleration and volumetric strain generated by the Parkfield 2004 earthquake on the GEOS strong-motion array near Parkfield, California

    Science.gov (United States)

    Borcherdt, Rodger D.; Johnston, Malcolm J.S.; Dietel, Christopher; Glassmoyer, Gary; Myren, Doug; Stephens, Christopher

    2004-01-01

    An integrated array of 11 General Earthquake Observation System (GEOS) stations installed near Parkfield, CA provided on scale broad-band, wide-dynamic measurements of acceleration and volumetric strain of the Parkfield earthquake (M 6.0) of September 28, 2004. Three component measurements of acceleration were obtained at each of the stations. Measurements of collocated acceleration and volumetric strain were obtained at four of the stations. Measurements of velocity at most sites were on scale only for the initial P-wave arrival. When considered in the context of the extensive set of strong-motion recordings obtained on more than 40 analog stations by the California Strong-Motion Instrumentation Program (Shakal, et al., 2004 http://www.quake.ca.gov/cisn-edc) and those on the dense array of Spudich, et al, (1988), these recordings provide an unprecedented document of the nature of the near source strong motion generated by a M 6.0 earthquake. The data set reported herein provides the most extensive set of near field broad band wide dynamic range measurements of acceleration and volumetric strain for an earthquake as large as M 6 of which the authors are aware. As a result considerable interest has been expressed in these data. This report is intended to describe the data and facilitate its use to resolve a number of scientific and engineering questions concerning earthquake rupture processes and resultant near field motions and strains. This report provides a description of the array, its scientific objectives and the strong-motion recordings obtained of the main shock. The report provides copies of the uncorrected and corrected data. Copies of the inferred velocities, displacements, and Psuedo velocity response spectra are provided. Digital versions of these recordings are accessible with information available through the internet at several locations: the National Strong-Motion Program web site (http://agram.wr.usgs.gov/), the COSMOS Virtual Data Center Web site

  11. Structural performance of the DOE's Idaho National Engineering Laboratory during the 1983 Borah Peak Earthquake

    International Nuclear Information System (INIS)

    Guenzler, R.C.; Gorman, V.W.

    1985-01-01

    The 1983 Borah Peak Earthquake (7.3 Richter magnitude) was the largest earthquake ever experienced by the DOE's Idaho National Engineering Laboratory (INEL). Reactor and plant facilities are generally located about 90 to 110 km (60 miles) from the epicenter. Several reactors were operating normally at the time of the earthquake. Based on detailed inspections, comparisons of measured accelerations with design levels, and instrumental seismograph information, it was concluded that the 1983 Borah Peak Earthquake created no safety problems for INEL reactors or other facilities. 10 references, 16 figures, 2 tables

  12. Spatial variations of earthquake occurrence and coseismic deformation in the Upper Rhine Graben, Central Europe

    Science.gov (United States)

    Barth, A.; Ritter, J. R. R.; Wenzel, F.

    2015-05-01

    Seismic activity in the densely populated Upper Rhine Graben (URG) is an aspect in the public, political, and industrial decision making process. The spatial analysis of magnitude-frequency distributions provides valuable information about local seismicity patterns and regional seismic hazard assessment and can be used also as a proxy for coseismic deformation to explore the seismo-tectonic setting of the URG. We combine five instrumental and one historic earthquake bulletins to obtain for the first time a consistent database for events with local magnitudes ML ≥ 2.0 in the whole URG and use it for the determination of magnitude frequencies. The data processing results in a dataset with 274 Poisson distributed instrumentally recorded earthquakes within the URG between 01/1971 and 02/2012 and 34 historic events since the year 1250. Our analysis reveals significant b-value variations along the URG that allow us to differentiate four distinct sections (I-IV) with significant differences in earthquake magnitude distributions: I: Basel region in the Swiss-France-German border region (b = 0.83), II: region between Mulhouse and Freiburg in the southern URG (b = 1.42), III: central URG (b = 0.93), and IV: northern URG (b = 1.06). High b-values and thus a relatively low amount of high magnitude events in the Freiburg section are possibly a consequence of strongly segmented, small-scale structures that are not able to accumulate high stresses. We use the obtained magnitude-frequency distributions and representative source mechanisms for each section to determine coseismic displacement rates. A maximum horizontal displacement rate of 41 μm/a around Basel is found whereas only 8 μm/a are derived for the central and northern URG. A comparison with geodetic and geological constraints implies that the coseismic displacement rates cover less than 10% of the overall displacement rates, suggesting a high amount of aseismic deformation in the URG.

  13. Earthquake number forecasts testing

    Science.gov (United States)

    Kagan, Yan Y.

    2017-10-01

    We study the distributions of earthquake numbers in two global earthquake catalogues: Global Centroid-Moment Tensor and Preliminary Determinations of Epicenters. The properties of these distributions are especially required to develop the number test for our forecasts of future seismic activity rate, tested by the Collaboratory for Study of Earthquake Predictability (CSEP). A common assumption, as used in the CSEP tests, is that the numbers are described by the Poisson distribution. It is clear, however, that the Poisson assumption for the earthquake number distribution is incorrect, especially for the catalogues with a lower magnitude threshold. In contrast to the one-parameter Poisson distribution so widely used to describe earthquake occurrences, the negative-binomial distribution (NBD) has two parameters. The second parameter can be used to characterize the clustering or overdispersion of a process. We also introduce and study a more complex three-parameter beta negative-binomial distribution. We investigate the dependence of parameters for both Poisson and NBD distributions on the catalogue magnitude threshold and on temporal subdivision of catalogue duration. First, we study whether the Poisson law can be statistically rejected for various catalogue subdivisions. We find that for most cases of interest, the Poisson distribution can be shown to be rejected statistically at a high significance level in favour of the NBD. Thereafter, we investigate whether these distributions fit the observed distributions of seismicity. For this purpose, we study upper statistical moments of earthquake numbers (skewness and kurtosis) and compare them to the theoretical values for both distributions. Empirical values for the skewness and the kurtosis increase for the smaller magnitude threshold and increase with even greater intensity for small temporal subdivision of catalogues. The Poisson distribution for large rate values approaches the Gaussian law, therefore its skewness

  14. Earthquake Source Spectral Study beyond the Omega-Square Model

    Science.gov (United States)

    Uchide, T.; Imanishi, K.

    2017-12-01

    Earthquake source spectra have been used for characterizing earthquake source processes quantitatively and, at the same time, simply, so that we can analyze the source spectra for many earthquakes, especially for small earthquakes, at once and compare them each other. A standard model for the source spectra is the omega-square model, which has the flat spectrum and the falloff inversely proportional to the square of frequencies at low and high frequencies, respectively, which are bordered by a corner frequency. The corner frequency has often been converted to the stress drop under the assumption of circular crack models. However, recent studies claimed the existence of another corner frequency [Denolle and Shearer, 2016; Uchide and Imanishi, 2016] thanks to the recent development of seismic networks. We have found that many earthquakes in areas other than the area studied by Uchide and Imanishi [2016] also have source spectra deviating from the omega-square model. Another part of the earthquake spectra we now focus on is the falloff rate at high frequencies, which will affect the seismic energy estimation [e.g., Hirano and Yagi, 2017]. In June, 2016, we deployed seven velocity seismometers in the northern Ibaraki prefecture, where the shallow crustal seismicity mainly with normal-faulting events was activated by the 2011 Tohoku-oki earthquake. We have recorded seismograms at 1000 samples per second and at a short distance from the source, so that we can investigate the high-frequency components of the earthquake source spectra. Although we are still in the stage of discovery and confirmation of the deviation from the standard omega-square model, the update of the earthquake source spectrum model will help us systematically extract more information on the earthquake source process.

  15. Rupture, waves and earthquakes.

    Science.gov (United States)

    Uenishi, Koji

    2017-01-01

    Normally, an earthquake is considered as a phenomenon of wave energy radiation by rupture (fracture) of solid Earth. However, the physics of dynamic process around seismic sources, which may play a crucial role in the occurrence of earthquakes and generation of strong waves, has not been fully understood yet. Instead, much of former investigation in seismology evaluated earthquake characteristics in terms of kinematics that does not directly treat such dynamic aspects and usually excludes the influence of high-frequency wave components over 1 Hz. There are countless valuable research outcomes obtained through this kinematics-based approach, but "extraordinary" phenomena that are difficult to be explained by this conventional description have been found, for instance, on the occasion of the 1995 Hyogo-ken Nanbu, Japan, earthquake, and more detailed study on rupture and wave dynamics, namely, possible mechanical characteristics of (1) rupture development around seismic sources, (2) earthquake-induced structural failures and (3) wave interaction that connects rupture (1) and failures (2), would be indispensable.

  16. Earthquakes and Earthquake Engineering. LC Science Tracer Bullet.

    Science.gov (United States)

    Buydos, John F., Comp.

    An earthquake is a shaking of the ground resulting from a disturbance in the earth's interior. Seismology is the (1) study of earthquakes; (2) origin, propagation, and energy of seismic phenomena; (3) prediction of these phenomena; and (4) investigation of the structure of the earth. Earthquake engineering or engineering seismology includes the…

  17. Simulation analysis of earthquake response of nuclear power plant to the 2003 Miyagi-Oki earthquake

    International Nuclear Information System (INIS)

    Yoshihiro Ogata; Kiyoshi Hirotani; Masayuki Higuchi; Shingo Nakayama

    2005-01-01

    On May 26, 2003 an earthquake of magnitude scale 7.1 (Japan Meteorological Agency) occurred just offshore of Miyagi Prefecture. This was the largest earthquake ever experienced by the nuclear power plant of Tohoku Electric Power Co. in Onagawa (hereafter the Onagawa Nuclear Power Plant) during the 19 years since it had started operations in 1984. In this report, we review the vibration characteristics of the reactor building of the Onagawa Nuclear Power Plant Unit 1 based on acceleration records observed at the building, and give an account of a simulation analysis of the earthquake response carried out to ascertain the appropriateness of design procedure and a seismic safety of the building. (authors)

  18. The 2007 Mentawai earthquake sequence on the Sumatra megathrust

    Science.gov (United States)

    Konca, A.; Avouac, J.; Sladen, A.; Meltzner, A. J.; Kositsky, A. P.; Sieh, K.; Fang, P.; Li, Z.; Galetzka, J.; Genrich, J.; Chlieh, M.; Natawidjaja, D. H.; Bock, Y.; Fielding, E. J.; Helmberger, D. V.

    2008-12-01

    The Sumatra Megathrust has recently produced a flurry of large interplate earthquakes starting with the giant Mw 9.15, Aceh earthquake of 2004. All of these earthquakes occurred within the area monitored by the Sumatra Geodetic Array (SuGAr), which provided exceptional records of near-field co-seismic and postseismic ground displacements. The most recent of these major earthquakes, an Mw 8.4 earthquake and an Mw 7.9 earthquake twelve hours later, occurred in the Mentawai islands area where devastating historical earthquakes had happened in 1797 and 1833. The 2007 earthquake sequence provides an exceptional opportunity to understand the variability of the earthquakes along megathrusts and their relation to interseismic coupling. The InSAR, GPS and teleseismic modeling shows that 2007 earthquakes ruptured a fraction of the strongly coupled Mentawai patch of the megathrust, which is also only a fraction of the 1833 rupture area. It also released a much smaller moment than the one released in 1833, or than the deficit of moment that has accumulated since. Both earthquakes of 2007 consist of 2 sub-events which are 50 to 100 km apart from each other. On the other hand, the northernmost slip patch of 8.4 and southern slip patch of 7.9 earthquakes abut each other, but they ruptured 12 hours apart. Sunda megathrust earthquakes of recent years include a rupture of a strongly coupled patch that closely mimics a prior rupture of that patch and which is well correlated with the interseismic coupling pattern (Nias-Simeulue section), as well as a rupture sequence of a strongly coupled patch that differs substantially in the details from its most recent predecessors (Mentawai section). We conclude that (1) seismic asperities are probably persistent features which arise form heterogeneous strain build up in the interseismic period; and (2) the same portion of a megathrust can rupture in different ways depending on whether asperities break as isolated events or cooperate to produce

  19. Instrumental interaction

    OpenAIRE

    Luciani , Annie

    2007-01-01

    International audience; The expression instrumental interaction as been introduced by Claude Cadoz to identify a human-object interaction during which a human manipulates a physical object - an instrument - in order to perform a manual task. Classical examples of instrumental interaction are all the professional manual tasks: playing violin, cutting fabrics by hand, moulding a paste, etc.... Instrumental interaction differs from other types of interaction (called symbolic or iconic interactio...

  20. The role of complex site and basin response in Wellington city, New Zealand, during the 2016 Mw 7.8 Kaikōura earthquake and other recent earthquake sequences.

    Science.gov (United States)

    Kaiser, A. E.; McVerry, G.; Wotherspoon, L.; Bradley, B.; Gerstenberger, M.; Benites, R. A.; Bruce, Z.; Bourguignon, S.; Giallini, S.; Hill, M.

    2017-12-01

    We present analysis of ground motion and complex amplification characteristics in Wellington during recent earthquake sequences and an overview of the 3D basin characterization and ongoing work to update site parameters for seismic design. Significant damage was observed in central Wellington, New Zealand's capital city, following the 2016 Mw7.8 Kaikōura earthquake. Damage was concentrated in mid-rise structures (5 - 15 storeys) and was clearly exacerbated by the particular characteristics of ground motion and the presence of basin effects. Due to the distance of the source (50 - 60km) from the central city, peak ground accelerations were moderate (up to 0.28g) and well within ultimate limit state (ULS) design levels. However, spectral accelerations within the 1 -2 s period range, exceeded 1 in 500 year design level spectra (ULS) in deeper parts of the basin. Amplification with respect to rock at these locations reached factors of up to 7, and was also observed with factors up to at least three across all central city soil recording sites. The ground motions in Wellington were the strongest recorded in the modern era of instrumentation. While similar amplification was observed during the 2013 Mw 6.6 Cook Strait and Grassmere earthquakes, which struck close to the termination of the Kaikōura earthquake rupture, these sources were not sufficiently large to excite significant long-period motions. However, other M7.2+ sources in the region that dominate the seismic hazard, e.g. Wellington Fault, Hikurangi subduction interface and other large proximal crustal faults, are also potentially capable of exciting significant long-period basin response in Wellington. These observations and the expectation of ongoing heightened seismicity have prompted re-evaluation of the current seismic demand levels. Additional field campaigns have also been undertaken to update geotechnical properties and the 3D basin model, in order to inform ongoing research and seismic design practice.

  1. Aseismic blocks and destructive earthquakes in the Aegean

    Science.gov (United States)

    Stiros, Stathis

    2017-04-01

    Aseismic areas are not identified only in vast, geologically stable regions, but also within regions of active, intense, distributed deformation such as the Aegean. In the latter, "aseismic blocks" about 200m wide were recognized in the 1990's on the basis of the absence of instrumentally-derived earthquake foci, in contrast to surrounding areas. This pattern was supported by the available historical seismicity data, as well as by geologic evidence. Interestingly, GPS evidence indicates that such blocks are among the areas characterized by small deformation rates relatively to surrounding areas of higher deformation. Still, the largest and most destructive earthquake of the 1990's, the 1995 M6.6 earthquake occurred at the center of one of these "aseismic" zones at the northern part of Greece, found unprotected against seismic hazard. This case was indeed a repeat of the case of the tsunami-associated 1956 Amorgos Island M7.4 earthquake, the largest 20th century event in the Aegean back-arc region: the 1956 earthquake occurred at the center of a geologically distinct region (Cyclades Massif in Central Aegean), till then assumed aseismic. Interestingly, after 1956, the overall idea of aseismic regions remained valid, though a "promontory" of earthquake prone-areas intruding into the aseismic central Aegean was assumed. Exploitation of the archaeological excavation evidence and careful, combined analysis of historical and archaeological data and other palaeoseismic, mostly coastal data, indicated that destructive and major earthquakes have left their traces in previously assumed aseismic blocks. In the latter earthquakes typically occur with relatively low recurrence intervals, >200-300 years, much smaller than in adjacent active areas. Interestingly, areas assumed a-seismic in antiquity are among the most active in the last centuries, while areas hit by major earthquakes in the past are usually classified as areas of low seismic risk in official maps. Some reasons

  2. Earthquakes; May-June 1982

    Science.gov (United States)

    Person, W.J.

    1982-01-01

    There were four major earthquakes (7.0-7.9) during this reporting period: two struck in Mexico, one in El Salvador, and one in teh Kuril Islands. Mexico, El Salvador, and China experienced fatalities from earthquakes.

  3. a Collaborative Cyberinfrastructure for Earthquake Seismology

    Science.gov (United States)

    Bossu, R.; Roussel, F.; Mazet-Roux, G.; Lefebvre, S.; Steed, R.

    2013-12-01

    One of the challenges in real time seismology is the prediction of earthquake's impact. It is particularly true for moderate earthquake (around magnitude 6) located close to urbanised areas, where the slightest uncertainty in event location, depth, magnitude estimates, and/or misevaluation of propagation characteristics, site effects and buildings vulnerability can dramatically change impact scenario. The Euro-Med Seismological Centre (EMSC) has developed a cyberinfrastructure to collect observations from eyewitnesses in order to provide in-situ constraints on actual damages. This cyberinfrastructure takes benefit of the natural convergence of earthquake's eyewitnesses on EMSC website (www.emsc-csem.org), the second global earthquake information website within tens of seconds of the occurrence of a felt event. It includes classical crowdsourcing tools such as online questionnaires available in 39 languages, and tools to collect geolocated pics. It also comprises information derived from the real time analysis of the traffic on EMSC website, a method named flashsourcing; In case of a felt earthquake, eyewitnesses reach EMSC website within tens of seconds to find out the cause of the shaking they have just been through. By analysing their geographical origin through their IP address, we automatically detect felt earthquakes and in some cases map the damaged areas through the loss of Internet visitors. We recently implemented a Quake Catcher Network (QCN) server in collaboration with Stanford University and the USGS, to collect ground motion records performed by volunteers and are also involved in a project to detect earthquakes from ground motions sensors from smartphones. Strategies have been developed for several social media (Facebook, Twitter...) not only to distribute earthquake information, but also to engage with the Citizens and optimise data collection. A smartphone application is currently under development. We will present an overview of this

  4. Probabilistic approach to earthquake prediction.

    Directory of Open Access Journals (Sweden)

    G. D'Addezio

    2002-06-01

    Full Text Available The evaluation of any earthquake forecast hypothesis requires the application of rigorous statistical methods. It implies a univocal definition of the model characterising the concerned anomaly or precursor, so as it can be objectively recognised in any circumstance and by any observer.A valid forecast hypothesis is expected to maximise successes and minimise false alarms. The probability gain associated to a precursor is also a popular way to estimate the quality of the predictions based on such precursor. Some scientists make use of a statistical approach based on the computation of the likelihood of an observed realisation of seismic events, and on the comparison of the likelihood obtained under different hypotheses. This method can be extended to algorithms that allow the computation of the density distribution of the conditional probability of earthquake occurrence in space, time and magnitude. Whatever method is chosen for building up a new hypothesis, the final assessment of its validity should be carried out by a test on a new and independent set of observations. The implementation of this test could, however, be problematic for seismicity characterised by long-term recurrence intervals. Even using the historical record, that may span time windows extremely variable between a few centuries to a few millennia, we have a low probability to catch more than one or two events on the same fault. Extending the record of earthquakes of the past back in time up to several millennia, paleoseismology represents a great opportunity to study how earthquakes recur through time and thus provide innovative contributions to time-dependent seismic hazard assessment. Sets of paleoseimologically dated earthquakes have been established for some faults in the Mediterranean area: the Irpinia fault in Southern Italy, the Fucino fault in Central Italy, the El Asnam fault in Algeria and the Skinos fault in Central Greece. By using the age of the

  5. Interplanetary variability recorded by the sled instrument aboard the Phobos spacecraft during that period of solar cycle 22 characterized by a transition from solar minimum- to solar maximum-dominated conditions

    Energy Technology Data Exchange (ETDEWEB)

    McKenna-Lawlor, S.M.P. (Saint Patrick' s Coll., Maynooth (Ireland)); Afonin, V.V.; Gringauz, K.I. (AN SSSR, Moscow (USSR). Space Research Inst.) (and others)

    Twin telescope particle detector systems SLED-1 and SLED-2, with the capability of monitoring electron and ion fluxes within an energy range spanning approximately 30 keV to a few megaelectron volts, were individually launched on the two spacecraft (Phobos-2 and Phobos-1, respectively) of the Soviet Phobos Mission to Mars and its moons in July 1988. A short description of the SLED instrument and a preliminary account of representative solar-related particle enhancements recorded by SLED-1 and SLED-2 during the Cruise Phase, and by SLED-1 in the near Martian environment (within the interval 25 July 1988-26 March 1989) are presented. These observations were made while the interplanetary medium was in the course of changing over from solar minimum- to solar maximum-dominated conditions and examples are presented of events associated with each of these phenomenological states. (author).

  6. Ocean bottom pressure observations near the source of the 2011 Tohoku earthquake

    Science.gov (United States)

    Inazu, D.; Hino, R.; Suzuki, S.; Osada, Y.; Ohta, Y.; Iinuma, T.; Tsushima, H.; Ito, Y.; Kido, M.; Fujimoto, H.

    2011-12-01

    A Mw9.0 earthquake occurred off Miyagi, northeast Japan, on 11 March 2011 (hereafter mainshock). An earthquake of M7.3, considered to be the largest foreshock of the mainshock, occurred on 9 March 2011 near the mainshock hypocenter. A suite of seismic and geodetic variations related to these earthquakes was observed by autonomous, ocean bottom pressure (OBP) gauges at multiple sites (4 sites at present) near the sources within a distance of about 100 km. This paper presents the OBP records with a focus on the earthquakes. Thanks to correcting tides, instrumental drifts, and non-tidal oceanic variations, we can detect OBP signals of tsunamis and vertical seafloor deformation of the order of centimeters with timescales of less than months. In the following we review the detected signals and how to correct the OBP data. The coseismic seafloor displacement and the tsunami accompanied by the mainshock were of the order of meters and large enough to be distinctly identified (Ito et al., 2011, GRL). Co- and post-seismic seafloor displacement and tsunami accompanied by the foreshock were of the order of centimeters which is difficult to be identified from the raw OBP records. The first evident pulses of these tsunamis in the deep sea have durations (periods) of ~20 minutes and ~10 minutes, for the mainshock and the foreshock, respectively. Amounts of seafloor vertical displacement due to post-mainshock deformation reached a few tens of centimeters in two months. It is worth noting that elevation and depression of seafloor were detected at rates of a couple of centimeters in a day after the largest foreshock. The seafloor displacement of centimeters between the largest foreshock and the mainshock can be reasonably identified after correcting non-tidal oceanic variations. The oceanic variations are simulated by a barotropic ocean model driven by atmospheric disturbances (Inazu et al., 2011, Ann. Rep. Earth Simulator Center 2011). The model enables residual OBP time series of

  7. Earthquakes of Garhwal Himalaya region of NW Himalaya, India: A study of relocated earthquakes and their seismogenic source and stress

    Science.gov (United States)

    R, A. P.; Paul, A.; Singh, S.

    2017-12-01

    Since the continent-continent collision 55 Ma, the Himalaya has accommodated 2000 km of convergence along its arc. The strain energy is being accumulated at a rate of 37-44 mm/yr and releases at time as earthquakes. The Garhwal Himalaya is located at the western side of a Seismic Gap, where a great earthquake is overdue atleast since 200 years. This seismic gap (Central Seismic Gap: CSG) with 52% probability for a future great earthquake is located between the rupture zones of two significant/great earthquakes, viz. the 1905 Kangra earthquake of M 7.8 and the 1934 Bihar-Nepal earthquake of M 8.0; and the most recent one, the 2015 Gorkha earthquake of M 7.8 is in the eastern side of this seismic gap (CSG). The Garhwal Himalaya is one of the ideal locations of the Himalaya where all the major Himalayan structures and the Himalayan Seimsicity Belt (HSB) can ably be described and studied. In the present study, we are presenting the spatio-temporal analysis of the relocated local micro-moderate earthquakes, recorded by a seismicity monitoring network, which is operational since, 2007. The earthquake locations are relocated using the HypoDD (double difference hypocenter method for earthquake relocations) program. The dataset from July, 2007- September, 2015 have been used in this study to estimate their spatio-temporal relationships, moment tensor (MT) solutions for the earthquakes of M>3.0, stress tensors and their interactions. We have also used the composite focal mechanism solutions for small earthquakes. The majority of the MT solutions show thrust type mechanism and located near the mid-crustal-ramp (MCR) structure of the detachment surface at 8-15 km depth beneath the outer lesser Himalaya and higher Himalaya regions. The prevailing stress has been identified to be compressional towards NNE-SSW, which is the direction of relative plate motion between the India and Eurasia continental plates. The low friction coefficient estimated along with the stress inversions

  8. Seismic instrumentation for nuclear power plants

    International Nuclear Information System (INIS)

    Senne Junior, M.

    1983-01-01

    A seismic instrumentation system used in Nuclear Power Plants to monitor the design parameters of systems, structures and components, needed to provide safety to those Plants, against the action of earthquakes is described. The instrumentation described is based on the nuclear standards in force. The minimum amount of sensors and other components used, as well as their general localization, is indicated. The operation of the instrumentation system as a whole and the handling of the recovered data are dealt with accordingly. The various devices used are not covered in detail, except for the accelerometer, which is the seismic instrumentation basic component. (Author) [pt

  9. Seismic recording at the Los Medanos area of Southeastern New Mexico, 1974-1975

    International Nuclear Information System (INIS)

    Sanford, A.R.; Johansen, S.J.; Caravella, F.J.; Ward, R.M.

    1976-01-01

    The objective has been to determine if low-level seismic activity is occurring at or near the proposed nuclear waste repository in southeastern New Mexico. The research involved installation and maintenance of a continuously recording seismograph at the Los Medanos site and interpretation of the seismic events detected by that station. The following topics are discussed: (1) a description of the seismic instrumentation and its performance; (2) statistics on the local and regional earthquakes detected by the seismograph station at the Los Medanos site; (3) special studies on the seismic events associated with rockfalls at the National Potash Co. Eddy County Mine on July 26, 1972 and November 28, 1974; and (4) improved estimates of recurrence intervals for major earthquakes likely to effect the Los Medanos site

  10. Romanian earthquakes analysis using BURAR seismic array

    International Nuclear Information System (INIS)

    Borleanu, Felix; Rogozea, Maria; Nica, Daniela; Popescu, Emilia; Popa, Mihaela; Radulian, Mircea

    2008-01-01

    Bucovina seismic array (BURAR) is a medium-aperture array, installed in 2002 in the northern part of Romania (47.61480 N latitude, 25.21680 E longitude, 1150 m altitude), as a result of the cooperation between Air Force Technical Applications Center, USA and National Institute for Earth Physics, Romania. The array consists of ten elements, located in boreholes and distributed over a 5 x 5 km 2 area; nine with short-period vertical sensors and one with a broadband three-component sensor. Since the new station has been operating the earthquake survey of Romania's territory has been significantly improved. Data recorded by BURAR during 01.01.2005 - 12.31.2005 time interval are first processed and analyzed, in order to establish the array detection capability of the local earthquakes, occurred in different Romanian seismic zones. Subsequently a spectral ratios technique was applied in order to determine the calibration relationships for magnitude, using only the information gathered by BURAR station. The spectral ratios are computed relatively to a reference event, considered as representative for each seismic zone. This method has the advantage to eliminate the path effects. The new calibration procedure is tested for the case of Vrancea intermediate-depth earthquakes and proved to be very efficient in constraining the size of these earthquakes. (authors)

  11. Earthquake-induced liquefaction in Ferland, Quebec

    International Nuclear Information System (INIS)

    Tuttle, M.; Seeber, L.

    1991-02-01

    Detailed geological investigations are under way at a number of liquefaction sites in the Ferland-Boilleau valley, Quebec, where sand boils, ground cracks and liquefaction-related damages to homes were documented immediately following the Ms=6.0, Mblg=6.5 Saguenay earthquake of November 25, 1988. To date, results obtained from these subsurface investigations of sand boils at two sites in Ferland, located about 26 km from the epicentre, indicate that: the Saguenay earthquake induced liquefaction in late-Pleistocene and Holocene sediments which was recorded as sand dikes, sills and vents in near-surface sediments and soils; earthquake-induced liquefaction and ground failure have occurred in this area at least three times in the past 10,000 years; and, the size and morphology of liquefaction features and the liquefaction susceptibility of source layers of the features may be indicative of the intensity of ground shaking. These preliminary results are very promising and suggest that with continued research liquefaction features will become a useful tool in glaciated terrains, such as northeastern North America, for determining not only the timing and location but also the size of past earthquakes

  12. The Development of an Earthquake Mind Mapping

    Directory of Open Access Journals (Sweden)

    Sri Adelila Sari

    2016-05-01

    Full Text Available The students were difficult to understand about earthquake caused the teaching methods used by teachers were still using the classic method. The teachers only used a textbook to teach the students without any other supporting equipments. Learning process by using the discourse method makes students thinking monotonically, so that only concentrated on the students' understanding of the matter presented by the teacher. Therefore, this study was aimed to develop an earthquake mind mapping to help students in the process of remembering and recording the material being taught by the teacher. The type of this study was Research and Development (R & D. Data were analyzed using descriptive statistics. The samples in this study were class of I-3Madrasah Tsanawiyah (MTs Darul Ulum Banda Aceh totaling 30 students. The results showed that mind mapping was developed by 5 stages in ADDIE models: analysis (analyzing the problem and find a solution, design (determine the learning strategies, development (producing an earthquake mind mapping to be used in the learning process, implementation (implementing learning activities using the media and evaluation (evaluating the learning activities. When students instructed to create their mind mapping, it was found that the products of mind mapping categorized in skilled and quite skilled were amounted to 73.33 and 26.66% respectively. As recommendation an earthquake mind mapping could be applied and useful as an effective learning.

  13. Expectable Earthquakes and their ground motions in the Van Norman Reservoirs Area

    Science.gov (United States)

    Wesson, R.L.; Page, R.A.; Boore, D.M.; Yerkes, R.F.

    1974-01-01

    The upper and lower Van Norman dams, in northwesternmost San Fernando Valley about 20 mi (32 km) northwest of downtown Los Angeles, were severely damaged during the 1971 San Fernando earthquake. An investigation of the geologic-seismologic setting of the Van Norman area indicates that an earthquake of at least M 7.7 may be expected in the Van Norman area. The expectable transitory effects in the Van Norman area of such an earthquake are as follows: peak horizontal acceleration of at least 1.15 g, peak velocity of displacement of 4.43 ft/sec (135 cm/sec), peak displacement of 2.3 ft (70 cm), and duration of shaking at accelerations greater than 0.05 g, 40 sec. A great earthquake (M 8+) on the San Andreas fault, 25 mi distant, also is expectable. Transitory effects in the Van Norman area from such an earthquake are estimated as follows: peak horizontal acceleration of 0.5 g, peak velocity of 1.97 ft/sec (60 cm/sec), displacement of 1.31 ft (40 cm), and duration of shaking at accelerations greater than 0.05 g, 80 sec. The permanent effects of the expectable local earthquake could include simultaneous fault movement at the lower damsite, the upper damsite, and the site proposed for a replacement dam halfway between the upper and lower dams. The maximum differential displacements due to such movements are estimated at 16.4 ft (5 m) at the lower damsite and about 9.6 ft (2.93 m) at the upper and proposed damsites. The 1971 San Fernando earthquake (M 6?) was accompanied by the most intense ground motions ever recorded instrumentally for a natural earthquake. At the lower Van Norman dam, horizontal accelerations exceeded 0.6 g, and shaking greater than 0.25 g lasted for about 13 see; at Pacoima dam, 6 mi (10 km) northeast of the lower dam, high-frequency peak horizontal accelerations of 1.25 g were recorded in two directions, and shaking greater than 0.25 g lasted for about 7 sec. Permanent effects of the earthquake include slope failures in the embankments of the upper

  14. Inversion of GPS-measured coseismic displacements for source parameters of Taiwan earthquake

    Science.gov (United States)

    Lin, J. T.; Chang, W. L.; Hung, H. K.; Yu, W. C.

    2016-12-01

    We performed a method of determining earthquake location, focal mechanism, and centroid moment tensor by coseismic surface displacements from daily and high-rate GPS measurements. Unlike commonly used dislocation model where fault geometry is calculated nonlinearly, our method makes a point source approach to evaluate these parameters in a solid and efficient way without a priori fault information and can thus provide constrains to subsequent finite source modeling of fault slip. In this study, we focus on the resolving ability of GPS data for moderate (Mw=6.0 7.0) earthquakes in Taiwan, and four earthquakes were investigated in detail: the March 27 2013 Nantou (Mw=6.0), the June 2 2013 Nantou (Mw=6.3) , the October 31 2013 Ruisui (Mw=6.3), and the March 31 2002 Hualien (ML=6.8) earthquakes. All these events were recorded by the Taiwan continuous GPS network with data sampling rates of 30-second and 1 Hz, where the Mw6.3 Ruisui earthquake was additionally recorded by another local GPS network with a sampling rate of 20 Hz. Our inverted focal mechanisms of all these earthquakes are consistent with the results of GCMT and USGS that evaluates source parameters by dynamic information from seismic waves. We also successfully resolved source parameters of the Mw6.3 Ruisui earthquake within only 10 seconds following the earthquake occurrence, demonstrating the potential of high-rate GPS data on earthquake early warning and real-time determination of earthquake source parameters.

  15. Sensing the earthquake

    Science.gov (United States)

    Bichisao, Marta; Stallone, Angela

    2017-04-01

    Making science visual plays a crucial role in the process of building knowledge. In this view, art can considerably facilitate the representation of the scientific content, by offering a different perspective on how a specific problem could be approached. Here we explore the possibility of presenting the earthquake process through visual dance. From a choreographer's point of view, the focus is always on the dynamic relationships between moving objects. The observed spatial patterns (coincidences, repetitions, double and rhythmic configurations) suggest how objects organize themselves in the environment and what are the principles underlying that organization. The identified set of rules is then implemented as a basis for the creation of a complex rhythmic and visual dance system. Recently, scientists have turned seismic waves into sound and animations, introducing the possibility of "feeling" the earthquakes. We try to implement these results into a choreographic model with the aim to convert earthquake sound to a visual dance system, which could return a transmedia representation of the earthquake process. In particular, we focus on a possible method to translate and transfer the metric language of seismic sound and animations into body language. The objective is to involve the audience into a multisensory exploration of the earthquake phenomenon, through the stimulation of the hearing, eyesight and perception of the movements (neuromotor system). In essence, the main goal of this work is to develop a method for a simultaneous visual and auditory representation of a seismic event by means of a structured choreographic model. This artistic representation could provide an original entryway into the physics of earthquakes.

  16. Turkish Children's Ideas about Earthquakes

    Science.gov (United States)

    Simsek, Canan Lacin

    2007-01-01

    Earthquake, a natural disaster, is among the fundamental problems of many countries. If people know how to protect themselves from earthquake and arrange their life styles in compliance with this, damage they will suffer will reduce to that extent. In particular, a good training regarding earthquake to be received in primary schools is considered…

  17. Earthquakes, May-June 1991

    Science.gov (United States)

    Person, W.J.

    1992-01-01

    One major earthquake occurred during this reporting period. This was a magntidue 7.1 in Indonesia (Minahassa Peninsula) on June 20. Earthquake-related deaths were reported in the Western Caucasus (Georgia, USSR) on May 3 and June 15. One earthquake-related death was also reported El Salvador on June 21. 

  18. Organizational changes at Earthquakes & Volcanoes

    Science.gov (United States)

    Gordon, David W.

    1992-01-01

    Primary responsibility for the preparation of Earthquakes & Volcanoes within the Geological Survey has shifted from the Office of Scientific Publications to the Office of Earthquakes, Volcanoes, and Engineering (OEVE). As a consequence of this reorganization, Henry Spall has stepepd down as Science Editor for Earthquakes & Volcanoes(E&V).

  19. Along-strike variations in fault frictional properties along the San Andreas Fault near Cholame, California from joint earthquake and low-frequency earthquake relocations

    Science.gov (United States)

    Harrington, Rebecca M.; Cochran, Elizabeth S.; Griffiths, Emily M.; Zeng, Xiangfang; Thurber, Clifford H.

    2016-01-01

    Recent observations of low‐frequency earthquakes (LFEs) and tectonic tremor along the Parkfield–Cholame segment of the San Andreas fault suggest slow‐slip earthquakes occur in a transition zone between the shallow fault, which accommodates slip by a combination of aseismic creep and earthquakes (fault, which accommodates slip by stable sliding (>35  km depth). However, the spatial relationship between shallow earthquakes and LFEs remains unclear. Here, we present precise relocations of 34 earthquakes and 34 LFEs recorded during a temporary deployment of 13 broadband seismic stations from May 2010 to July 2011. We use the temporary array waveform data, along with data from permanent seismic stations and a new high‐resolution 3D velocity model, to illuminate the fine‐scale details of the seismicity distribution near Cholame and the relation to the distribution of LFEs. The depth of the boundary between earthquakes and LFE hypocenters changes along strike and roughly follows the 350°C isotherm, suggesting frictional behavior may be, in part, thermally controlled. We observe no overlap in the depth of earthquakes and LFEs, with an ∼5  km separation between the deepest earthquakes and shallowest LFEs. In addition, clustering in the relocated seismicity near the 2004 Mw 6.0 Parkfield earthquake hypocenter and near the northern boundary of the 1857 Mw 7.8 Fort Tejon rupture may highlight areas of frictional heterogeneities on the fault where earthquakes tend to nucleate.

  20. Facts learnt from the Hanshin-Awaji disaster and consideration on design basis earthquake

    International Nuclear Information System (INIS)

    Shibata, Heki

    1997-01-01

    This paper will deal with how to establish the concept of the design basis earthquake for critical industrial facilities such as nuclear power plants in consideration of disasters induced by the 1995 Hyogoken-Nanbu Earthquake (Southern Hyogo-prefecture Earthquake-1995), so-called Kobe earthquake. The author once discussed various DBEs at 7 WCEE. At that time, the author assumed that the strongest effective PGA would be 0.7 G, and compared to the values of accelerations to a structure obtained by various codes in Japan and other countries. The maximum PGA observed by an instrument at the Southern Hyogo-pref. Earthquake-1995 exceeded the previous assumption of the author, even though the evaluation results of the previous paper had been pessimistic. According to the experience of Kobe event, the author will point out the necessity of the third earthquake S s adding to S 1 and S 2 , previous DBEs. (author)

  1. Facts learnt from the Hanshin-Awaji disaster and consideration on design basis earthquake

    Energy Technology Data Exchange (ETDEWEB)

    Shibata, Heki [Yokohama National Univ. (Japan). Faculty of Engineering

    1997-03-01

    This paper will deal with how to establish the concept of the design basis earthquake for critical industrial facilities such as nuclear power plants in consideration of disasters induced by the 1995 Hyogoken-Nanbu Earthquake (Southern Hyogo-prefecture Earthquake-1995), so-called Kobe earthquake. The author once discussed various DBEs at 7 WCEE. At that time, the author assumed that the strongest effective PGA would be 0.7 G, and compared to the values of accelerations to a structure obtained by various codes in Japan and other countries. The maximum PGA observed by an instrument at the Southern Hyogo-pref. Earthquake-1995 exceeded the previous assumption of the author, even though the evaluation results of the previous paper had been pessimistic. According to the experience of Kobe event, the author will point out the necessity of the third earthquake S{sub s} adding to S{sub 1} and S{sub 2}, previous DBEs. (author)

  2. The 1976 Tangshan earthquake

    Science.gov (United States)

    Fang, Wang

    1979-01-01

    The Tangshan earthquake of 1976 was one of the largest earthquakes in recent years. It occurred on July 28 at 3:42 a.m, Beijing (Peking) local time, and had magnitude 7.8, focal depth of 15 kilometers, and an epicentral intensity of XI on the New Chinese Seismic Intensity Scale; it caused serious damage and loss of life in this densely populated industrial city. Now, with the help of people from all over China, the city of Tangshan is being rebuild. 

  3. [Earthquakes in El Salvador].

    Science.gov (United States)

    de Ville de Goyet, C

    2001-02-01

    The Pan American Health Organization (PAHO) has 25 years of experience dealing with major natural disasters. This piece provides a preliminary review of the events taking place in the weeks following the major earthquakes in El Salvador on 13 January and 13 February 2001. It also describes the lessons that have been learned over the last 25 years and the impact that the El Salvador earthquakes and other disasters have had on the health of the affected populations. Topics covered include mass-casualties management, communicable diseases, water supply, managing donations and international assistance, damages to the health-facilities infrastructure, mental health, and PAHO's role in disasters.

  4. The 2016 Kumamoto Earthquakes: Cascading Geological Hazards and Compounding Risks

    Directory of Open Access Journals (Sweden)

    Katsuichiro Goda

    2016-08-01

    Full Text Available A sequence of two strike-slip earthquakes occurred on 14 and 16 April 2016 in the intraplate region of Kyushu Island, Japan, apart from subduction zones, and caused significant damage and disruption to the Kumamoto region. The analyses of regional seismic catalog and available strong motion recordings reveal striking characteristics of the events, such as migrating seismicity, earthquake surface rupture, and major foreshock-mainshock earthquake sequences. To gain valuable lessons from the events, a UK Earthquake Engineering Field Investigation Team (EEFIT was dispatched to Kumamoto, and earthquake damage surveys were conducted to relate observed earthquake characteristics to building and infrastructure damage caused by the earthquakes. The lessons learnt from the reconnaissance mission have important implications on current seismic design practice regarding the required seismic resistance of structures under multiple shocks and the seismic design of infrastructure subject to large ground deformation. The observations also highlight the consequences of cascading geological hazards on community resilience. To share the gathered damage data widely, geo-tagged photos are organized using Google Earth and the kmz file is made publicly available.

  5. Ultimate limit states of steel containment vessel under earthquake loadings

    International Nuclear Information System (INIS)

    Akiyama, Hiroshi; Yuhara, Tetsuo; Shimizu, Seiichi; Hayashi, Kazutoshi; Takahashi, Tadao.

    1986-01-01

    The limit state induced by buckling of cylindrical steel structures under earthquake loadings was investigated from the standpoint of energy concept. A number of the buckling test of cylindrical steel shell structures has been made, which showed that they have a stable load-displacement relation and adequate deformation capacities beyond the buckling. The authors are proposing that the energy input imparted by strong earthquakes to buckled structures and the deformation capacity in post-buckling are suitable indices for seismic resistance of the cylindrical steel shell structures because the buckling does not cause the structure immediately to collapse in the case of such repeated loading as earthquake motions. The purpose of this study is to investigate the energy input to buckled cylindrical steel structures with an increase in the intensity of earthquake motions. A series of nonlinear dynamic analyses were performed under various types of earthquake records by using a hysteresis loop, including buckling, which was derived from the buckling tests. The limit state could be defined as the state in which the deformation of and the energy input into buckled structures increase divergently when the intensity of the earthquake excitation exceeds a certain value. The results obtained in this paper are intended to be adopted to the limit state in the post-buckling region to evaluate the margin of safety against the buckling resistance of cylindrical steel structures under strong earthquake loadings. (author)

  6. An interdisciplinary approach to study Pre-Earthquake processes

    Science.gov (United States)

    Ouzounov, D.; Pulinets, S. A.; Hattori, K.; Taylor, P. T.

    2017-12-01

    We will summarize a multi-year research effort on wide-ranging observations of pre-earthquake processes. Based on space and ground data we present some new results relevant to the existence of pre-earthquake signals. Over the past 15-20 years there has been a major revival of interest in pre-earthquake studies in Japan, Russia, China, EU, Taiwan and elsewhere. Recent large magnitude earthquakes in Asia and Europe have shown the importance of these various studies in the search for earthquake precursors either for forecasting or predictions. Some new results were obtained from modeling of the atmosphere-ionosphere connection and analyses of seismic records (foreshocks /aftershocks), geochemical, electromagnetic, and thermodynamic processes related to stress changes in the lithosphere, along with their statistical and physical validation. This cross - disciplinary approach could make an impact on our further understanding of the physics of earthquakes and the phenomena that precedes their energy release. We also present the potential impact of these interdisciplinary studies to earthquake predictability. A detail summary of our approach and that of several international researchers will be part of this session and will be subsequently published in a new AGU/Wiley volume. This book is part of the Geophysical Monograph series and is intended to show the variety of parameters seismic, atmospheric, geochemical and historical involved is this important field of research and will bring this knowledge and awareness to a broader geosciences community.

  7. Earthquake forecasting studies using radon time series data in Taiwan

    Science.gov (United States)

    Walia, Vivek; Kumar, Arvind; Fu, Ching-Chou; Lin, Shih-Jung; Chou, Kuang-Wu; Wen, Kuo-Liang; Chen, Cheng-Hong

    2017-04-01

    For few decades, growing number of studies have shown usefulness of data in the field of seismogeochemistry interpreted as geochemical precursory signals for impending earthquakes and radon is idendified to be as one of the most reliable geochemical precursor. Radon is recognized as short-term precursor and is being monitored in many countries. This study is aimed at developing an effective earthquake forecasting system by inspecting long term radon time series data. The data is obtained from a network of radon monitoring stations eastblished along different faults of Taiwan. The continuous time series radon data for earthquake studies have been recorded and some significant variations associated with strong earthquakes have been observed. The data is also examined to evaluate earthquake precursory signals against environmental factors. An automated real-time database operating system has been developed recently to improve the data processing for earthquake precursory studies. In addition, the study is aimed at the appraisal and filtrations of these environmental parameters, in order to create a real-time database that helps our earthquake precursory study. In recent years, automatic operating real-time database has been developed using R, an open source programming language, to carry out statistical computation on the data. To integrate our data with our working procedure, we use the popular and famous open source web application solution, AMP (Apache, MySQL, and PHP), creating a website that could effectively show and help us manage the real-time database.

  8. Earthquake swarms and the semidiurnal solid earth tide

    Energy Technology Data Exchange (ETDEWEB)

    Klein, F W

    1976-01-01

    Several correlations between peak earthquake activity during swarms and the phase and stress orientation of the calculated solid earth tide are described. The events correlating with the tide are clusters of swarm earthquakes. Swarm clusters from many sequences recorded over several years are used. Significant tidal correlations (which have less than a 5% chance of being observed if earthquakes were random) are found in the Reykjanes Peninsula in Iceland, the central Mid-Atlantic Ridge, the Imperial Valley and northern Gulf of California, and larger (m/sub b/ greater than or equal to 5.0) aftershocks of the 1965 Rat Islands earthquake. In addition, sets of larger single earthquakes on Atlantic and north-east Pacific fracture zones are significantly correlated with the calculated solid tide. No tidal correlation, however, could be found for the Matsushiro Japan swarm of 1965 to 1967. The earthquake-tide correlations other than those of the Reykjanes Peninsula and Mid-Atlantic Ridge can be interpreted as triggering caused by enhancement of the tectonic stress by tidal stress, i.e. the alignment of fault and tidal principal stresses. All tidal correlations except in the Aleutians are associated with oceanic rifts or their landward extensions. If lithospheric plates are decoupled at active rifts, then tidal stresses channeled along the lithospheric stress guide may be concentrated at ridge-type plate boundaries. Tidal triggering of earthquakes at rifts may reflect this possible amplification of tidal strains in the weakened lithosphere at ridges. 25 figures, 2 tables.

  9. The 2016 Central Italy Earthquake: an Overview

    Science.gov (United States)

    Amato, A.

    2016-12-01

    The M6 central Italy earthquake occurred on the seismic backbone of the Italy, just in the middle of the highest hazard belt. The shock hit suddenly during the night of August 24, when people were asleep; no foreshocks occurred before the main event. The earthquake ruptured from 10 km to the surface, and produced a more than 17,000 aftershocks (Oct. 19) spread on a 40x20 km2 area elongated NW-SE. It is geologically very similar to previous recent events of the Apennines. Both the 2009 L'Aquila earthquake to the south and the 1997 Colfiorito to the north, were characterized by the activation of adjacent fault segments. Despite its magnitude and the well known seismic hazard of the region, the earthquake produced extensive damage and 297 fatalities. The town of Amatrice, that paid the highest toll, was classified in zone 1 (the highest) since 1915, but the buildings in this and other villages revealed highly vulnerable. In contrast, in the town of Norcia, that also experienced strong ground shaking, no collapses occurred, most likely due to the retrofitting carried out after an earthquake in 1979. Soon after the quake, the INGV Crisis Unit convened at night in the Rome headquarters, in order to coordinate the activities. The first field teams reached the epicentral area at 7 am with the portable seismic stations installed to monitor the aftershocks; other teams followed to map surface faults, damage, to measure GPS sites, to install instruments for site response studies, and so on. The INGV Crisis Unit includes the Press office and the INGVterremoti team, in order to manage and coordinate the communication towards the Civil Protection Dept. (DPC), the media and the web. Several tens of reports and updates have been delivered in the first month of the sequence to DPC. Also due to the controversial situation arisen from the L'Aquila earthquake and trials, particular attention was given to the communication: continuous and timely information has been released to

  10. Sedimentary Signatures of Submarine Earthquakes: Deciphering the Extent of Sediment Remobilization from the 2011 Tohoku Earthquake and Tsunami and 2010 Haiti Earthquake

    Science.gov (United States)

    McHugh, C. M.; Seeber, L.; Moernaut, J.; Strasser, M.; Kanamatsu, T.; Ikehara, K.; Bopp, R.; Mustaque, S.; Usami, K.; Schwestermann, T.; Kioka, A.; Moore, L. M.

    2017-12-01

    The 2004 Sumatra-Andaman Mw9.3 and the 2011 Tohoku (Japan) Mw9.0 earthquakes and tsunamis were huge geological events with major societal consequences. Both were along subduction boundaries and ruptured portions of these boundaries that had been deemed incapable of such events. Submarine strike-slip earthquakes, such as the 2010 Mw7.0 in Haiti, are smaller but may be closer to population centers and can be similarly catastrophic. Both classes of earthquakes remobilize sediment and leave distinct signatures in the geologic record by a wide range of processes that depends on both environment and earthquake characteristics. Understanding them has the potential of greatly expanding the record of past earthquakes, which is critical for geohazard analysis. Recent events offer precious ground truth about the earthquakes and short-lived radioisotopes offer invaluable tools to identify sediments they remobilized. In the 2011 Mw9 Japan earthquake they document the spatial extent of remobilized sediment from water depths of 626m in the forearc slope to trench depths of 8000m. Subbottom profiles, multibeam bathymetry and 40 piston cores collected by the R/V Natsushima and R/V Sonne expeditions to the Japan Trench document multiple turbidites and high-density flows. Core tops enriched in xs210Pb,137Cs and 134Cs reveal sediment deposited by the 2011 Tohoku earthquake and tsunami. The thickest deposits (2m) were documented on a mid-slope terrace and trench (4000-8000m). Sediment was deposited on some terraces (600-3000m), but shed from the steep forearc slope (3000-4000m). The 2010 Haiti mainshock ruptured along the southern flank of Canal du Sud and triggered multiple nearshore sediment failures, generated turbidity currents and stirred fine sediment into suspension throughout this basin. A tsunami was modeled to stem from both sediment failures and tectonics. Remobilized sediment was tracked with short-lived radioisotopes from the nearshore, slope, in fault basins including the

  11. Earthquake Culture: A Significant Element in Earthquake Disaster Risk Assessment and Earthquake Disaster Risk Management

    OpenAIRE

    Ibrion, Mihaela

    2018-01-01

    This book chapter brings to attention the dramatic impact of large earthquake disasters on local communities and society and highlights the necessity of building and enhancing the earthquake culture. Iran was considered as a research case study and fifteen large earthquake disasters in Iran were investigated and analyzed over more than a century-time period. It was found that the earthquake culture in Iran was and is still conditioned by many factors or parameters which are not integrated and...

  12. The mechanism of earthquake

    Science.gov (United States)

    Lu, Kunquan; Cao, Zexian; Hou, Meiying; Jiang, Zehui; Shen, Rong; Wang, Qiang; Sun, Gang; Liu, Jixing

    2018-03-01

    The physical mechanism of earthquake remains a challenging issue to be clarified. Seismologists used to attribute shallow earthquake to the elastic rebound of crustal rocks. The seismic energy calculated following the elastic rebound theory and with the data of experimental results upon rocks, however, shows a large discrepancy with measurement — a fact that has been dubbed as “the heat flow paradox”. For the intermediate-focus and deep-focus earthquakes, both occurring in the region of the mantle, there is not reasonable explanation either. This paper will discuss the physical mechanism of earthquake from a new perspective, starting from the fact that both the crust and the mantle are discrete collective system of matters with slow dynamics, as well as from the basic principles of physics, especially some new concepts of condensed matter physics emerged in the recent years. (1) Stress distribution in earth’s crust: Without taking the tectonic force into account, according to the rheological principle of “everything flows”, the normal stress and transverse stress must be balanced due to the effect of gravitational pressure over a long period of time, thus no differential stress in the original crustal rocks is to be expected. The tectonic force is successively transferred and accumulated via stick-slip motions of rock blocks to squeeze the fault gouge and then exerted upon other rock blocks. The superposition of such additional lateral tectonic force and the original stress gives rise to the real-time stress in crustal rocks. The mechanical characteristics of fault gouge are different from rocks as it consists of granular matters. The elastic moduli of the fault gouges are much less than those of rocks, and they become larger with increasing pressure. This peculiarity of the fault gouge leads to a tectonic force increasing with depth in a nonlinear fashion. The distribution and variation of the tectonic stress in the crust are specified. (2) The

  13. A preliminary regional assessment of earthquake-induced landslide susceptibility for Vrancea Seismic Region

    Science.gov (United States)

    Micu, Mihai; Balteanu, Dan; Ionescu, Constantin; Havenith, Hans; Radulian, Mircea; van Westen, Cees; Damen, Michiel; Jurchescu, Marta

    2015-04-01

    In seismically-active regions, earthquakes may trigger landslides enhancing the short-to-long term slope denudation and sediment delivery and conditioning the general landscape evolution. Co-seismic slope failures present in general a low frequency - high magnitude pattern which should be addressed accordingly by landslide hazard assessment, with respect to the generally more frequent precipitation-triggered landslides. The Vrancea Seismic Region, corresponding to the curvature sector of the Eastern Romanian Carpathians, represents the most active sub-crustal (focal depth > 50 km) earthquake province of Europe. It represents the main seismic energy source throughout Romania with significant transboundary effects recorded as far as Ukraine and Bulgaria. During the last 300 years, the region featured 14 earthquakes with M>7, among which seven events with magnitude above 7.5 and three between 7.7 and 7.9. Apart from the direct damages, the Vrancea earthquakes are also responsible for causing numerous other geohazards, such as ground fracturing, groundwater level disturbances and possible deep-seated landslide occurrences (rock slumps, rock-block slides, rock falls, rock avalanches). The older deep-seated landslides (assumed to have been) triggered by earthquakes usually affect the entire slope profile. They often formed landslide dams strongly influencing the river morphology and representing potential threats (through flash-floods) in case of lake outburst. Despite the large potential of this research issue, the correlation between the region's seismotectonic context and landslide predisposing factors has not yet been entirely understood. Presently, there is a lack of information provided by the geohazards databases of Vrancea that does not allow us to outline the seismic influence on the triggering of slope failures in this region. We only know that the morphology of numerous large, deep-seated and dormant landslides (which can possibly be reactivated in future

  14. The analysis of historical seismograms: an important tool for seismic hazard assessment. Case histories from French and Italian earthquakes

    International Nuclear Information System (INIS)

    Pino, N.A.

    2011-01-01

    Seismic hazard assessment relies on the knowledge of the source characteristics of past earthquakes. Unfortunately, seismic waveform analysis, representing the most powerful tool for the investigation of earthquake source parameters, is only possible for events occurred in the last 100-120 years, i.e., since seismographs with known response function were developed. Nevertheless, during this time significant earthquakes have been recorded by such instruments and today, also thanks to technological progress, these data can be recovered and analysed by means of modern techniques. In this paper, aiming at giving a general sketch of possible analyses and attainable results in historical seismogram studies, I briefly describe the major difficulties in processing the original waveforms and present a review of the results that I obtained from previous seismogram analysis of selected significant historical earthquakes occurred during the first decades of the 20. century, including (A) the December 28, 1908, Messina straits (southern Italy), (B) the June 11, 1909, Lambesc (southern France) - both of which are the strongest ever recorded instrumentally in their respective countries - and (C) the July 13, 1930, Irpinia (southern Italy) events. For these earthquakes, the major achievements are represented by the assessment of the seismic moment (A, B, C), the geometry and kinematics of faulting (B, C), the fault length and an approximate slip distribution (A, C). The source characteristics of the studied events have also been interpreted in the frame of the tectonic environment active in the respective region of interest. In spite of the difficulties inherent to the investigation of old seismic data, these results demonstrate the invaluable and irreplaceable role of historical seismogram analysis in defining the local seismo-genic potential and, ultimately, for assessing the seismic hazard. The retrieved information is crucial in areas where important civil engineering works

  15. Application of τc*Pd for identifying damaging earthquakes for earthquake early warning

    Science.gov (United States)

    Huang, P. L.; Lin, T. L.; Wu, Y. M.

    2014-12-01

    Earthquake Early Warning System (EEWS) is an effective approach to mitigate earthquake damage. In this study, we used the seismic record by the Kiban Kyoshin network (KiK-net), because it has dense station coverage and co-located borehole strong-motion seismometers along with the free-surface strong-motion seismometers. We used inland earthquakes with moment magnitude (Mw) from 5.0 to 7.3 between 1998 and 2012. We choose 135 events and 10950 strong ground accelerograms recorded by the 696 strong ground accelerographs. Both the free-surface and the borehole data are used to calculate τc and Pd, respectively. The results show that τc*Pd has a good correlation with PGV and is a robust parameter for assessing the potential of damaging earthquake. We propose the value of τc*Pd determined from seconds after the arrival of P wave could be a threshold for the on-site type of EEW.

  16. Earthquake Swarm in Armutlu Peninsula, Eastern Marmara Region, Turkey

    Science.gov (United States)

    Yavuz, Evrim; Çaka, Deniz; Tunç, Berna; Serkan Irmak, T.; Woith, Heiko; Cesca, Simone; Lühr, Birger-Gottfried; Barış, Şerif

    2015-04-01

    The most active fault system of Turkey is North Anatolian Fault Zone and caused two large earthquakes in 1999. These two earthquakes affected the eastern Marmara region destructively. Unbroken part of the North Anatolian Fault Zone crosses north of Armutlu Peninsula on east-west direction. This branch has been also located quite close to Istanbul known as a megacity with its high population, economic and social aspects. A new cluster of microseismic activity occurred in the direct vicinity southeastern of the Yalova Termal area. Activity started on August 2, 2014 with a series of micro events, and then on August 3, 2014 a local magnitude is 4.1 event occurred, more than 1000 in the followed until August 31, 2014. Thus we call this tentatively a swarm-like activity. Therefore, investigation of the micro-earthquake activity of the Armutlu Peninsula has become important to understand the relationship between the occurrence of micro-earthquakes and the tectonic structure of the region. For these reasons, Armutlu Network (ARNET), installed end of 2005 and equipped with currently 27 active seismic stations operating by Kocaeli University Earth and Space Sciences Research Center (ESSRC) and Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum (GFZ), is a very dense network tool able to record even micro-earthquakes in this region. In the 30 days period of August 02 to 31, 2014 Kandilli Observatory and Earthquake Research Institute (KOERI) announced 120 local earthquakes ranging magnitudes between 0.7 and 4.1, but ARNET provided more than 1000 earthquakes for analyzes at the same time period. In this study, earthquakes of the swarm area and vicinity regions determined by ARNET were investigated. The focal mechanism of the August 03, 2014 22:22:42 (GMT) earthquake with local magnitude (Ml) 4.0 is obtained by the moment tensor solution. According to the solution, it discriminates a normal faulting with dextral component. The obtained focal mechanism solution is

  17. Short-period strain (0.1-105 s): Near-source strain field for an earthquake (M L 3.2) near San Juan Bautista, California

    Science.gov (United States)

    Johnston, M. J. S.; Borcherdt, R. D.; Linde, A. T.

    1986-10-01

    Measurements of dilational earth strain in the frequency band 25-10-5 Hz have been made on a deep borehole strainmeter installed near the San Andreas fault. These data are used to determine seismic radiation fields during nuclear explosions, teleseisms, local earthquakes, and ground noise during seismically quiet times. Strains of less than 10-10 on these instruments can be clearly resolved at short periods (< 10 s) and are recorded with wide dynamic range digital recorders. This permits measurement of the static and dynamic strain variations in the near field of local earthquakes. Noise spectra for earth strain referenced to 1 (strain)2/Hz show that strain resolution decreases at about 10 dB per decade of frequency from -150 dB at 10-4 Hz to -223 dB at 10 Hz. Exact expressions are derived to relate the volumetric strain and displacement field for a homogeneous P wave in a general viscoelastic solid as observed on colocated dilatometers and seismometers. A rare near-field recording of strain and seismic velocity was obtained on May 26, 1984, from an earthquake (ML 3.2) at a hypocentral distance of 3.2 km near the San Andreas fault at San Juan Bautista, California. While the data indicate no precursory strain release at the 5 × 10-11 strain level, a coseismic strain release of 1.86 nanostrain was observed. This change in strain is consistent with that calculated from a simple dislocation model of the event. Ground displacement spectra, determined from the downhole strain data and instrument-corrected surface seismic data, suggest that source parameters estimated from surface recordings may be contaminated by amplification effects in near-surface low-velocity materials.

  18. Large earthquake rates from geologic, geodetic, and seismological perspectives

    Science.gov (United States)

    Jackson, D. D.

    2017-12-01

    Earthquake rate and recurrence information comes primarily from geology, geodesy, and seismology. Geology gives the longest temporal perspective, but it reveals only surface deformation, relatable to earthquakes only with many assumptions. Geodesy is also limited to surface observations, but it detects evidence of the processes leading to earthquakes, again subject to important assumptions. Seismology reveals actual earthquakes, but its history is too short to capture important properties of very large ones. Unfortunately, the ranges of these observation types barely overlap, so that integrating them into a consistent picture adequate to infer future prospects requires a great deal of trust. Perhaps the most important boundary is the temporal one at the beginning of the instrumental seismic era, about a century ago. We have virtually no seismological or geodetic information on large earthquakes before then, and little geological information after. Virtually all-modern forecasts of large earthquakes assume some form of equivalence between tectonic- and seismic moment rates as functions of location, time, and magnitude threshold. That assumption links geology, geodesy, and seismology, but it invokes a host of other assumptions and incurs very significant uncertainties. Questions include temporal behavior of seismic and tectonic moment rates; shape of the earthquake magnitude distribution; upper magnitude limit; scaling between rupture length, width, and displacement; depth dependence of stress coupling; value of crustal rigidity; and relation between faults at depth and their surface fault traces, to name just a few. In this report I'll estimate the quantitative implications for estimating large earthquake rate. Global studies like the GEAR1 project suggest that surface deformation from geology and geodesy best show the geography of very large, rare earthquakes in the long term, while seismological observations of small earthquakes best forecasts moderate earthquakes

  19. The EM Earthquake Precursor

    Science.gov (United States)

    Jones, K. B., II; Saxton, P. T.

    2013-12-01

    Many attempts have been made to determine a sound forecasting method regarding earthquakes and warn the public in turn. Presently, the animal kingdom leads the precursor list alluding to a transmission related source. By applying the animal-based model to an electromagnetic (EM) wave model, various hypotheses were formed, but the most interesting one required the use of a magnetometer with a differing design and geometry. To date, numerous, high-end magnetometers have been in use in close proximity to fault zones for potential earthquake forecasting; however, something is still amiss. The problem still resides with what exactly is forecastable and the investigating direction of EM. After the 1989 Loma Prieta Earthquake, American earthquake investigators predetermined magnetometer use and a minimum earthquake magnitude necessary for EM detection. This action was set in motion, due to the extensive damage incurred and public outrage concerning earthquake forecasting; however, the magnetometers employed, grounded or buried, are completely subject to static and electric fields and have yet to correlate to an identifiable precursor. Secondly, there is neither a networked array for finding any epicentral locations, nor have there been any attempts to find even one. This methodology needs dismissal, because it is overly complicated, subject to continuous change, and provides no response time. As for the minimum magnitude threshold, which was set at M5, this is simply higher than what modern technological advances have gained. Detection can now be achieved at approximately M1, which greatly improves forecasting chances. A propagating precursor has now been detected in both the field and laboratory. Field antenna testing conducted outside the NE Texas town of Timpson in February, 2013, detected three strong EM sources along with numerous weaker signals. The antenna had mobility, and observations were noted for recurrence, duration, and frequency response. Next, two

  20. Fire and earthquake counter measures in radiation handling facilities

    International Nuclear Information System (INIS)

    1985-01-01

    'Fire countermeasures in radiation handling facilities' published in 1961 is still widely utilized as a valuable guideline for those handling radiation through the revision in 1972. However, science and technology rapidly advanced, and the relevant laws were revised after the publication, and many points which do not conform to the present state have become to be found. Therefore, it was decided to rewrite this book, and the new book has been completed. The title was changed to 'Fire and earthquake countermeasures in radiation handling facilities', and the countermeasures to earthquakes were added. Moreover, consideration was given so that the book is sufficiently useful also for those concerned with fire fighting, not only for those handling radiation. In this book, the way of thinking about the countermeasures against fires and earthquakes, the countermeasures in normal state and when a fire or an earthquake occurred, the countermeasures when the warning declaration has been announced, and the data on fires, earthquakes, the risk of radioisotopes, fire fighting equipment, the earthquake counter measures for equipment, protectors and radiation measuring instruments, first aid, the example of emergency system in radiation handling facilities, the activities of fire fighters, the example of accidents and so on are described. (Kako, I.)

  1. Discrimination Analysis of Earthquakes and Man-Made Events Using ARMA Coefficients Determination by Artificial Neural Networks

    International Nuclear Information System (INIS)

    AllamehZadeh, Mostafa

    2011-01-01

    A Quadratic Neural Networks (QNNs) model has been developed for identifying seismic source classification problem at regional distances using ARMA coefficients determination by Artificial Neural Networks (ANNs). We have devised a supervised neural system to discriminate between earthquakes and chemical explosions with filter coefficients obtained by windowed P-wave phase spectra (15 s). First, we preprocess the recording's signals to cancel out instrumental and attenuation site effects and obtain a compact representation of seismic records. Second, we use a QNNs system to obtain ARMA coefficients for feature extraction in the discrimination problem. The derived coefficients are then applied to the neural system to train and classification. In this study, we explore the possibility of using single station three-component (3C) covariance matrix traces from a priori-known explosion sites (learning) for automatically recognizing subsequent explosions from the same site. The results have shown that this feature extraction gives the best classifier for seismic signals and performs significantly better than other classification methods. The events have been tested, which include 36 chemical explosions at the Semipalatinsk test site in Kazakhstan and 61 earthquakes (mb = 5.0–6.5) recorded by the Iranian National Seismic Network (INSN). The 100% correct decisions were obtained between site explosions and some of non-site events. The above approach to event discrimination is very flexible as we can combine several 3C stations.

  2. Discrimination Analysis of Earthquakes and Man-Made Events Using ARMA Coefficients Determination by Artificial Neural Networks

    Energy Technology Data Exchange (ETDEWEB)

    AllamehZadeh, Mostafa, E-mail: dibaparima@yahoo.com [International Institute of Earthquake Engineering and Seismology (Ir