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Sample records for earthquake accelerograms digitized

  1. Mapping the rupture process of moderate earthquakes by inverting accelerograms

    USGS Publications Warehouse

    Hellweg, M.; Boatwright, J.

    1999-01-01

    We present a waveform inversion method that uses recordings of small events as Green's functions to map the rupture growth of moderate earthquakes. The method fits P and S waveforms from many stations simultaneously in an iterative procedure to estimate the subevent rupture time and amplitude relative to the Green's function event. We invert the accelerograms written by two moderate Parkfield earthquakes using smaller events as Green's functions. The first earthquake (M = 4.6) occurred on November 14, 1993, at a depth of 11 km under Middle Mountain, in the assumed preparation zone for the next Parkfield main shock. The second earthquake (M = 4.7) occurred on December 20, 1994, some 6 km to the southeast, at a depth of 9 km on a section of the San Andreas fault with no previous microseismicity and little inferred coseismic slip in the 1966 Parkfield earthquake. The inversion results are strikingly different for the two events. The average stress release in the 1993 event was 50 bars, distributed over a geometrically complex area of 0.9 km2. The average stress release in the 1994 event was only 6 bars, distributed over a roughly elliptical area of 20 km2. The ruptures of both events appear to grow spasmodically into relatively complex shapes: the inversion only constrains the ruptures to grow more slowly than the S wave velocity but does not use smoothness constraints. Copyright 1999 by the American Geophysical Union.

  2. The near-source strong-motion accelerograms recorded by an experimental array in Tangshan, China

    USGS Publications Warehouse

    Peng, K.; Xie, Lingtian; Li, S.; Boore, D.M.; Iwan, W.D.; Teng, T.L.

    1985-01-01

    A joint research project on strong-motion earthquake studies between the People's Republic of China and the United States is in progress. As a part of this project, an experimental strong-motion array, consisting of twelve Kinemetrics PDR-1 Digital Event Recorders, was deployed in the meizoseismal area of the Ms = 7.8 Tangshan earthquake of July 28, 1976. These instruments have automatic gain ranging, a specified dynamic range of 102 dB, a 2.5 s pre-event memory, programmable triggering, and are equipped with TCG-1B Time Code Generators with a stability of 3 parts in 107 over a range of 0-50??C. In 2 y of operation beginning July, 1982 a total of 603 near-source 3-component accelerograms were gathered from 243 earthquakes of magnitude ML = 1.2-5.3. Most of these accelerograms have recorded the initial P-wave. The configuration of the experimental array and a representative set of near-source strong-motion accelerograms are presented in this paper. The set of accelerograms exhibited were obtained during the ML = 5.3 Lulong earthquake of October 19, 1982, when digital event recorders were triggered. The epicentral distances ranged from 4 to 41 km and the corresponding range of peak horizontal accelerations was 0.232g to 0.009g. A preliminary analysis of the data indicates that compared to motions in the western United States, the peak acceleration attenuates much more rapidly in the Tangshan area. The scaling of peak acceleration with magnitude, however, is similar in the two regions. Data at more distant sites are needed to confirm the more rapid attenuation. ?? 1985.

  3. Processing of strong-motion accelerograms: Needs, options and consequences

    USGS Publications Warehouse

    Boore, D.M.; Bommer, J.J.

    2005-01-01

    Recordings from strong-motion accelerographs are of fundamental importance in earthquake engineering, forming the basis for all characterizations of ground shaking employed for seismic design. The recordings, particularly those from analog instruments, invariably contain noise that can mask and distort the ground-motion signal at both high and low frequencies. For any application of recorded accelerograms in engineering seismology or earthquake engineering, it is important to identify the presence of this noise in the digitized time-history and its influence on the parameters that are to be derived from the records. If the parameters of interest are affected by noise then appropriate processing needs to be applied to the records, although it must be accepted from the outset that it is generally not possible to recover the actual ground motion over a wide range of frequencies. There are many schemes available for processing strong-motion data and it is important to be aware of the merits and pitfalls associated with each option. Equally important is to appreciate the effects of the procedures on the records in order to avoid errors in the interpretation and use of the results. Options for processing strong-motion accelerograms are presented, discussed and evaluated from the perspective of engineering application. ?? 2004 Elsevier Ltd. All rights reserved.

  4. On Drift Effects in Velocity and Displacement of Greek Uncorrected Digital Strong Motion Data

    NASA Astrophysics Data System (ADS)

    Skarlatoudis, A.; Margaris, B.

    2005-12-01

    Fifty years after the first installation of analog accelerographs, digital instruments recording the strong-motion came in operation. Their advantages comparing to the analog ones are obvious and they have been described in detail in several works. Nevertheless it has been pointed out that velocity and displacement values derived from several accelerograms, recorded in various strong earthquakes worldwide (e.g. 1999 Chi-Chi, Taiwan, Hector Mine, 2002 Denali) by digital instruments, are plagued by drifts when only a simple baseline correction derived from the pre-event portion of the record is removed. In Greece a significant number of accelerographic networks and arrays have been deployed covering the whole area. Digital accelerographs now constitute a significant part of the National Strong Motion network of the country. Detailed analyses of the data processing of accelerograms recorded by digital instruments exhibited that the same drifts exist in the Greek strong motion database. In this work, a methodology proposed and described in various articles (Boore, 2001; 2003; 2005) for removing the aforementioned drifts of the accelerograms is applied. It is also attempted a careful look of the nature of the drifts for understanding the noise characteristics relative to the signal. The intrinsic behaviour of signal to noise ratio is crucial for the adequacy of baseline corrections applied on digital uncorrected accelerograms. Velocities and displacements of the uncorrected and corrected accelerograms are compared and the drift effects in the Fourier and response spectra are presented.

  5. Neural Models: An Option to Estimate Seismic Parameters of Accelerograms

    NASA Astrophysics Data System (ADS)

    Alcántara, L.; García, S.; Ovando-Shelley, E.; Macías, M. A.

    2014-12-01

    Seismic instrumentation for recording strong earthquakes, in Mexico, goes back to the 60´s due the activities carried out by the Institute of Engineering at Universidad Nacional Autónoma de México. However, it was after the big earthquake of September 19, 1985 (M=8.1) when the project of seismic instrumentation assumes a great importance. Currently, strong ground motion networks have been installed for monitoring seismic activity mainly along the Mexican subduction zone and in Mexico City. Nevertheless, there are other major regions and cities that can be affected by strong earthquakes and have not yet begun their seismic instrumentation program or this is still in development.Because of described situation some relevant earthquakes (e.g. Huajuapan de León Oct 24, 1980 M=7.1, Tehuacán Jun 15, 1999 M=7 and Puerto Escondido Sep 30, 1999 M= 7.5) have not been registered properly in some cities, like Puebla and Oaxaca, and that were damaged during those earthquakes. Fortunately, the good maintenance work carried out in the seismic network has permitted the recording of an important number of small events in those cities. So in this research we present a methodology based on the use of neural networks to estimate significant duration and in some cases the response spectra for those seismic events. The neural model developed predicts significant duration in terms of magnitude, epicenter distance, focal depth and soil characterization. Additionally, for response spectra we used a vector of spectral accelerations. For training the model we selected a set of accelerogram records obtained from the small events recorded in the strong motion instruments installed in the cities of Puebla and Oaxaca. The final results show that neural networks as a soft computing tool that use a multi-layer feed-forward architecture provide good estimations of the target parameters and they also have a good predictive capacity to estimate strong ground motion duration and response spectra.

  6. Digital radiography of crush thoracic trauma in the Sichuan earthquake

    PubMed Central

    Dong, Zhi-Hui; Shao, Heng; Chen, Tian-Wu; Chu, Zhi-Gang; Deng, Wen; Tang, Si-Shi; Chen, Jing; Yang, Zhi-Gang

    2011-01-01

    AIM: To investigate the features of crush thoracic trauma in Sichuan earthquake victims using chest digital radiography (CDR). METHODS: We retrospectively reviewed 772 CDR of 417 females and 355 males who had suffered crush thoracic trauma in the Sichuan earthquake. Patient age ranged from 0.5 to 103 years. CDR was performed between May 12, 2008 and June 7, 2008. We looked for injury to the thoracic cage, pulmonary parenchyma and the pleura. RESULTS: Antero-posterior (AP) and lateral CDR were obtained in 349 patients, the remaining 423 patients underwent only AP CDR. Thoracic cage fractures, pulmonary contusion and pleural injuries were noted in 331 (42.9%; 95% CI: 39.4%-46.4%), 67 and 135 patients, respectively. Of the 256 patients with rib fractures, the mean number of fractured ribs per patient was 3. Rib fractures were mostly distributed from the 3rd through to the 8th ribs and the vast majority involved posterior and lateral locations along the rib. Rib fractures had a significant positive association with non-rib thoracic fractures, pulmonary contusion and pleural injuries (P < 0.001). The number of rib fractures and pulmonary contusions were significant factors associated with patient death. CONCLUSION: Earthquake-related crush thoracic trauma has the potential for multiple fractures. The high number of fractured ribs and pulmonary contusions were significant factors which needed appropriate medical treatment. PMID:22132298

  7. Earthquakes

    MedlinePlus

    ... Search Term(s): Main Content Home Be Informed Earthquakes Earthquakes An earthquake is the sudden, rapid shaking of the earth, ... by the breaking and shifting of underground rock. Earthquakes can cause buildings to collapse and cause heavy ...

  8. Earthquakes

    MedlinePlus

    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 ...

  9. A stochastic estimate of ground motion at Oceano, California, for the M 6.5 22 December 2003 San Simeon earthquake, derived from aftershock recordings

    USGS Publications Warehouse

    Di, Alessandro C.; Boatwright, J.

    2006-01-01

    The U.S. Geological Survey deployed a digital seismic station in Oceano, California, in February 2004, to investigate the cause of damage and liquefaction from the 22 December 2003 M 6.5 San Simeon earthquake. This station recorded 11 M > 2.8 aftershocks in almost 8 weeks. We analyze these recordings, together with recordings of the mainshock and the same aftershocks obtained from nearby stations in Park Hill and San Luis Obispo, to estimate the mainshock ground motion in Oceano. We estimate the Fourier amplitude spectrum using generalized spectral ratio analysis. We test a set of aftershocks as Green's functions by comparing simulated and recorded acceleration amplitude spectra for the mainshock at San Luis Obispo and Park Hill. We convolve the aftershock accelerograms with a stochastic operator to simulate the duration and phase of the mainshock accelerograms. This approximation allows us to extend the range of aftershocks that can be used as Green's functions to events nearly three magnitude units smaller than the mainshock. Our realizations for the mainshock accelerogram at Oceano yield peak ground accelerations distributed as 28% ?? 4%g. We interpret these realizations as upper bounds for the actual ground motion, because our analysis assumes a linear response, whereas the presence of liquefaction indicates that the ground behaved nonlinearly in Oceano.

  10. Earthquakes.

    ERIC Educational Resources Information Center

    Pakiser, Louis C.

    One of a series of general interest publications on science topics, the booklet provides those interested in earthquakes with an introduction to the subject. Following a section presenting an historical look at the world's major earthquakes, the booklet discusses earthquake-prone geographic areas, the nature and workings of earthquakes, earthquake…

  11. Earthquakes.

    ERIC Educational Resources Information Center

    Walter, Edward J.

    1977-01-01

    Presents an analysis of the causes of earthquakes. Topics discussed include (1) geological and seismological factors that determine the effect of a particular earthquake on a given structure; (2) description of some large earthquakes such as the San Francisco quake; and (3) prediction of earthquakes. (HM)

  12. Surface Rupture Map of the 2002 M7.9 Denali Fault Earthquake, Alaska: Digital Data

    USGS Publications Warehouse

    Haeussler, Peter J.

    2009-01-01

    The November 3, 2002, Mw7.9 Denali Fault earthquake produced about 340 km of surface rupture along the Susitna Glacier Thrust Fault and the right-lateral, strike-slip Denali and Totschunda Faults. Digital photogrammetric methods were primarily used to create a 1:500-scale, three-dimensional surface rupture map, and 1:6,000-scale aerial photographs were used for three-dimensional digitization in ESRI's ArcMap GIS software, using Leica's StereoAnalyst plug in. Points were digitized 4.3 m apart, on average, for the entire surface rupture. Earthquake-induced landslides, sackungen, and unruptured Holocene fault scarps on the eastern Denali Fault were also digitized where they lay within the limits of air photo coverage. This digital three-dimensional fault-trace map is superior to traditional maps in terms of relative and absolute accuracy, completeness, and detail and is used as a basis for three-dimensional visualization. Field work complements the air photo observations in locations of dense vegetation, on bedrock, or in areas where the surface trace is weakly developed. Seventeen km of the fault trace, which broke through glacier ice, were not digitized in detail due to time constraints, and air photos missed another 10 km of fault rupture through the upper Black Rapids Glacier, so that was not mapped in detail either.

  13. Local magnitude determinations for intermountain seismic belt earthquakes from broadband digital data

    USGS Publications Warehouse

    Pechmann, J.C.; Nava, S.J.; Terra, F.M.; Bernier, J.C.

    2007-01-01

    The University of Utah Seismograph Stations (UUSS) earthquake catalogs for the Utah and Yellowstone National Park regions contain two types of size measurements: local magnitude (ML) and coda magnitude (MC), which is calibrated against ML. From 1962 through 1993, UUSS calculated ML values for southern and central Intermountain Seismic Belt earthquakes using maximum peak-to-peak (p-p) amplitudes on paper records from one to five Wood-Anderson (W-A) seismographs in Utah. For ML determinations of earthquakes since 1994, UUSS has utilized synthetic W-A seismograms from U.S. National Seismic Network and UUSS broadband digital telemetry stations in the region, which numbered 23 by the end of our study period on 30 June 2002. This change has greatly increased the percentage of earthquakes for which ML can be determined. It is now possible to determine ML for all M ???3 earthquakes in the Utah and Yellowstone regions and earthquakes as small as M <1 in some areas. To maintain continuity in the magnitudes in the UUSS earthquake catalogs, we determined empirical ML station corrections that minimize differences between MLs calculated from paper and synthetic W-A records. Application of these station corrections, in combination with distance corrections from Richter (1958) which have been in use at UUSS since 1962, produces ML values that do not show any significant distance dependence. ML determinations for the Utah and Yellowstone regions for 1981-2002 using our station corrections and Richter's distance corrections have provided a reliable data set for recalibrating the MC scales for these regions. Our revised ML values are consistent with available moment magnitude determinations for Intermountain Seismic Belt earthquakes. To facilitate automatic ML measurements, we analyzed the distribution of the times of maximum p-p amplitudes in synthetic W-A records. A 30-sec time window for maximum amplitudes, beginning 5 sec before the predicted Sg time, encompasses 95% of the

  14. Earthquake!

    ERIC Educational Resources Information Center

    Hernandez, Hildo

    2000-01-01

    Examines the types of damage experienced by California State University at Northridge during the 1994 earthquake and what lessons were learned in handling this emergency are discussed. The problem of loose asbestos is addressed. (GR)

  15. Surface Deformation Associated with the 1983 Borah Peak Earthquake Measured from Digital Surface Model Differencing

    NASA Astrophysics Data System (ADS)

    Reitman, N. G.; Briggs, R.; Gold, R. D.; DuRoss, C. B.

    2015-12-01

    Post-earthquake, field-based assessments of surface displacement commonly underestimate offsets observed with remote sensing techniques (e.g., InSAR, image cross-correlation) because they fail to capture the total deformation field. Modern earthquakes are readily characterized by comparing pre- and post-event remote sensing data, but historical earthquakes often lack pre-event data. To overcome this challenge, we use historical aerial photographs to derive pre-event digital surface models (DSMs), which we compare to modern, post-event DSMs. Our case study focuses on resolving on- and off-fault deformation along the Lost River fault that accompanied the 1983 M6.9 Borah Peak, Idaho, normal-faulting earthquake. We use 343 aerial images from 1952-1966 and vertical control points selected from National Geodetic Survey benchmarks measured prior to 1983 to construct a pre-event point cloud (average ~ 0.25 pts/m2) and corresponding DSM. The post-event point cloud (average ~ 1 pt/m2) and corresponding DSM are derived from WorldView 1 and 2 scenes processed with NASA's Ames Stereo Pipeline. The point clouds and DSMs are coregistered using vertical control points, an iterative closest point algorithm, and a DSM coregistration algorithm. Preliminary results of differencing the coregistered DSMs reveal a signal spanning the surface rupture that is consistent with tectonic displacement. Ongoing work is focused on quantifying the significance of this signal and error analysis. We expect this technique to yield a more complete understanding of on- and off-fault deformation patterns associated with the Borah Peak earthquake along the Lost River fault and to help improve assessments of surface deformation for other historical ruptures.

  16. Digital disaster evaluation and its application to 2015 Ms 8.1 Nepal Earthquake

    NASA Astrophysics Data System (ADS)

    WANG, Xiaoqing; LV, Jinxia; DING, Xiang; DOU, Aixia

    2016-11-01

    The purpose of the article is to probe the technique resolution of disaster information extraction and evaluation from the digital RS images based on the internet environment and aided by the social and geographic information. The solution is composed with such methods that the fast post-disaster assessment system will assess automatically the disaster area and grade, the multi-phase satellite and airborne high resolution digital RS images will provide the basis to extract the disaster areas or spots, assisted by the fast position of potential serious damage risk targets according to the geographic, administrative, population, buildings and other information in the estimated disaster region, the 2D digital map system or 3D digital earth system will provide platforms to interpret cooperatively the damage information in the internet environment, and further to estimate the spatial distribution of damage index or intensity, casualties or economic losses, which are very useful for the decision-making of emergency rescue and disaster relief, resettlement and reconstruction. The spatial seismic damage distribution of 2015 Ms 8.1 Nepal earthquake, as an example of the above solution, is evaluated by using the high resolution digital RS images, auxiliary geographic information and ground survey. The results are compared with the statistical disaster information issued by the ground truth by field surveying, and show good consistency.

  17. Voluntary Activities and Online Education for Digital Heritage Inventory Development after the Great East Japan Earthquake

    NASA Astrophysics Data System (ADS)

    Kondo, Y.; Uozu, T.; Seino, Y.; Ako, T.; Goda, Y.; Fujimoto, Y.; Yamaguchi, H.

    2013-07-01

    Consortium for Earthquake-Damaged Cultural Heritage (CEDACH) is a voluntary initiative launched just after the Great East Japan Earthquake on 11 March 2011. The consortium is developing a social network between local cultural resource managers restoring disaster-damaged cultural heritage on one side and remote researchers including historians, archaeologists and specialists of cultural information studies on the other side, in order to facilitate collaborative projects. This paper presents three projects in which CEDACH contributed to the development of a digital inventory for disaster-damaged heritage management through web-based collaborations by self-motivated workers. The first project, CEDACH GIS, developed an online archaeological site inventory for the disaster area. Although a number of individuals voluntarily participated in the project at the beginning, it gradually stagnated due to limited need for local rescue archaeology. However, the experience of online-based collaborations worked well for the second project proposed by local specialists, in which CEDACH restored the book catalogue of a tsunami-devastated research library. This experience highlighted the need for online education to improve information and communication technologies (ICT) skills of data builders. Therefore, in the third project called CEDACHeLi, an e-Learning management system was developed to facilitate learning the fundamental knowledge and techniques required for information processing in rescue operations of disaster-damaged cultural heritage. This system will contribute to improved skills and motivation of potential workers for further developments in digital heritage inventory.

  18. Did we really #prayfornepal? Instagram posts as a massive digital funeral in Nepal earthquake aftermath

    NASA Astrophysics Data System (ADS)

    Kamil, P. I.; Pratama, A. J.; Hidayatulloh, A.

    2016-05-01

    Social media has been part of our daily life for years, and now it has become a treasure trove of data for social scientists to mine. Using our own data mining engine we downloaded 1500 Instagram posts related to the Nepal earthquake in April 2015, a disaster which caused tremendous losses counted in human lives and infrastructures. We predicted that the social media will be a place where people respond and express themselves emotionally in light of a disaster of such massive scale, a "megadeath" event. We ended up with data on 1017 posts tracked with the hashtag #prayfornepal, consisting of the post's date, time, geolocation, image, post ID, username and ID, caption, and hashtag. We categorized the posts into 7 categories and found that most of the photos (30,29%) are related to Nepal but not directly related to the disasters, which reflects death imprint, one of psychosocial responses after a megadeath event. Other analyses were done to compare each photo category, including geo-location, hashtag network and caption network which will be visualized with ArcGIS, NodeXL, Gephi, and our own word cloud engine to examine other digital reactions to Nepal Earthquake in Instagram. This study can give an overview of how community reacts to a disaster in digital world and utilize it for disaster response and awareness.

  19. Faults, lineaments, and earthquake epicenters digital map of the Pahute Mesa 30' x 60' Quadrangle, Nevada

    USGS Publications Warehouse

    Minor, S.A.; Vick, G.S.; Carr, M.D.; Wahl, R.R.

    1996-01-01

    This map database, identified as Faults, lineaments, and earthquake epicenters digital map of the Pahute Mesa 30' X 60' quadrangle, Nevada, has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use. This digital map compilation incorporates fault, air photo lineament, and earthquake epicenter data from within the Pahute Mesa 30' by 60' quadrangle, southern Nye County, Nevada (fig. 1). The compilation contributes to the U.S. Department of Energy's Yucca Mountain Project, established to determine whether or not the Yucca Mountain site is suitable for the disposal of high-level nuclear waste. Studies of local and regional faulting and earthquake activity, including the features depicted in this compilation, are carried out to help characterize seismic hazards and tectonic processes that may be relevant to the future stability of Yucca Mountain. The Yucca Mountain site is located in the central part of the Beatty 30' by 60' quadrangle approximately 15 km south of the south edge of the Pahute Mesa quadrangle (fig. 1). The U.S. Geological Survey participates in studies of the Yucca Mountain site under Interagency Agreement DE-AI08-78ET44802. The map compilation is only available on line as a digital database in ARC/INFO ASCII (Generate) and export formats. The database can be downloaded via 'anonymous ftp' from a USGS system named greenwood.cr.usgs.gov (136.177.48.5). The files are located in a directory named /pub/open-file-reports/ofr-96-0262. This directory contains a text document named 'README.1 ST' that contains database technical and explanatory documentation, including instructions for

  20. Comments on baseline correction of digital strong-motion data: Examples from the 1999 Hector Mine, California, earthquake

    USGS Publications Warehouse

    Boore, D.M.; Stephens, C.D.; Joyner, W.B.

    2002-01-01

    Residual displacements for large earthquakes can sometimes be determined from recordings on modern digital instruments, but baseline offsets of unknown origin make it difficult in many cases to do so. To recover the residual displacement, we suggest tailoring a correction scheme by studying the character of the velocity obtained by integration of zeroth-order-corrected acceleration and then seeing if the residual displacements are stable when the various parameters in the particular correction scheme are varied. For many seismological and engineering purposes, however, the residual displacement are of lesser importance than ground motions at periods less than about 20 sec. These ground motions are often recoverable with simple baseline correction and low-cut filtering. In this largely empirical study, we illustrate the consequences of various correction schemes, drawing primarily from digital recordings of the 1999 Hector Mine, California, earthquake. We show that with simple processing the displacement waveforms for this event are very similar for stations separated by as much as 20 km. We also show that a strong pulse on the transverse component was radiated from the Hector Mine earthquake and propagated with little distortion to distances exceeding 170 km; this pulse leads to large response spectral amplitudes around 10 sec.

  1. Changes of Earthquake Vulnerability of Marunouchi and Ginza Area in Tokyo and Urban Recovery Digital Archives on Google Earth

    NASA Astrophysics Data System (ADS)

    Igarashi, Masayasu; Murao, Osamu

    In this paper, the authors develop a multiple regression model which estimates urban earthquake vulnerability (building collapse risk and conflagration risk) for different eras, and clarify the historical changes of urban risk in Marunouchi and Ginza Districts in Tokyo, Japan using old maps and contemporary geographic information data. Also, we compare the change of urban vulnerability of the districts with the significant historical events in Tokyo. Finally, the results are loaded onto Google Earth with timescale extension to consider the possibility of urban recovery digital archives in the era of the recent geoinformatic technologies.

  2. Community Digital Library Requirements for the Southern California Earthquake Center Community Modeling Environment (SCEC/CME)

    NASA Astrophysics Data System (ADS)

    Moore, R.; Faerman, M.; Minster, J.; Day, S. M.; Ely, G.

    2003-12-01

    A community digital library provides support for ingestion, organization, description, preservation, and access of digital entities. The technologies that traditionally provide these capabilities are digital libraries (ingestion, organization, description), persistent archives (preservation) and data grids (access). We present a design for the SCEC community digital library that incorporates aspects of all three systems. Multiple groups have created integrated environments that sustain large-scale scientific data collections. By examining these projects, the following stages of implementation can be identified: \\begin{itemize} Definition of semantic terms to associate with relevant information. This includes definition of uniform content descriptors to describe physical quantities relevant to the scientific discipline, and creation of concept spaces to define how the uniform content descriptors are logically related. Organization of digital entities into logical collections that make it simple to browse and manage related material. Definition of services that are used to access and manipulate material in the collection. Creation of a preservation environment for the long-term management of the collection. Each community is faced with heterogeneity that is introduced when data is distributed across multiple sites, or when multiple sets of collection semantics are used, and or when multiple scientific sub-disciplines are federated. We will present the relevant standards that simplify the implementation of the SCEC community library, the resource requirements for different types of data sets that drive the implementation, and the digital library processes that the SCEC community library will support. The SCEC community library can be viewed as the set of processing steps that are required to build the appropriate SCEC reference data sets (SCEC approved encoding format, SCEC approved descriptive metadata, SCEC approved collection organization, and SCEC managed storage

  3. State-of-the-Art for Assessing Earthquake Hazards in the United States. Report 28. Recommended Accelerograms for Earthquake Ground Motions

    DTIC Science & Technology

    1992-06-01

    Rodolfo H. eu al., December 1985. Analisis de los Acelero- gramas del Terremoto del 3 de Marzo de 1985: University of Chile, Pub- lication SES I 4/1985 (199...196741975 Records: Open-File Report (unpublished). Mexico 1974 Prince, Jorge at al., February 1976 . Procesamiento de Acelerograas Obtenidos on 1974:, UNAM...engineering profession. The recent Mexican Guerrero data is a welcome exception to this generalization. 9 Calculations 24 . Few calculations were required for

  4. Rupture characteristics of the three M ∼ 4.7 (1992-1994) Parkfield earthquakes

    USGS Publications Warehouse

    Fletcher, Jon Peter B.; Spudich, Paul A.

    1998-01-01

    Slip on the San Andreas fault was determined for three M ∼ 4.7 earthquakes using a tomographic inverse system [Beroza and Spudich, 1988] to invert seismic source time functions (STFs) from S waves. STFs were obtained by deconvolving mainshock accelerograms by those from collocated smaller earthquakes. Accelerograms were from the U.S. Geological Survey Parkfield Small Aperture Array (UPSAR) and from a distributed array of digital accelerometer stations at Parkfield. Eight or nine STFs are used in each of the three inversions. STFs are typically symmetrical pulses with a duration of about 0.3–0.5 s. In the inversion, mainshock rise time was set to 0.05 s, and we allowed the rupture time to vary slightly from a constant rupture velocity of approximately 0.85β. Rupture for all three events, which are located in or close to the Middle Mountain preparation zone or box (MMB), quickly reaches a local maximum in slip and then propagates outward to peaks, ridges, or plateaus in the slip distribution. Slip for the October 20, 1992, event (located just inside the southern edge of the MMB) propagates from an initial spike north and updip along a curving ridge for about 2 km. The initial spike continued to grow in the November 14, 1993, event (located north of the October 20, 1992, event just beneath the hypocenter of the 1966 Parkfield earthquake), which shows little directivity, although there is a smaller patch of slip updip and to the south. In contrast, rupture for the December 20, 1994, event (located just south of the October 20, 1992, event) propagated north and slightly updip, creating a rough plateau in slip a few kilometers wide on a side. Directivity for this event also is to the north. Directivity for all three events points in the approximate direction of the 1966 hypocenter. Small pulses, which comprise a coda, are found on the STFs for several seconds after the initial impulsive event. Several tests based on the assumption that the average of all STFs

  5. Seismology and Earthquake Ground Motions of the August 24, 2014 M6 South Napa Earthquake

    NASA Astrophysics Data System (ADS)

    Kishida, T.; Wang, S.; Mazzoni, S.; Markam, C.; Lu, Y.; Bozorgnia, Y.; Mahin, S.; Bray, J.; Panagiotou, M.; Stewart, J. P.; Darragh, R. B.; Abrahamson, N. A.; Hollenback, J. C.; Gutierrez, C.; Chiou, B.; Muin, S.; Dreger, D. S.

    2014-12-01

    The M6.0 South Napa earthquake produced strong ground motions in the northern San Francisco Bay area. A total of 214 three-component uncorrected digital accelerograms were downloaded from the CESMD website and processed following the PEER standard procedure (Ancheta et al. 2014). Intense ground motions were recorded in the heavily damaged area of Napa with peak acceleration greater than 0.3 g. Pulse-like waveforms were observed in several of the velocity time series at the near-fault stations. Near-fault velocity time series were rotated into fault normal and fault parallel directions and then characterized as pulse-like or non pulse-like according to previous studies by Hayden et al. (2014), Shahi (2013), and Lu and Panagiotou (2014). The near-fault velocity time series at five stations contained pulses with periods within the expected range of 0.7 s to 2.0 s for soil sites (Bray et al. 2009). However, they also contained longer period pulses than the expected range. High-frequency spikes were recorded at Carquinez Bridge Geotechnical Array #1 (CBGA1) of approximately 1.0 g on the NS component. These spikes were in the S-wave portion and were consistently observed in the downhole arrays and several other sites along the same azimuth from the source. The spikes increase in amplitude both from the Hwy 37/Napa River East Geotechnical Array to CBGA1 and from a depth below 100 m to the surface. This suggests that the spikes could be a result of path effects and site amplification through the surficial soft soil deposits. However, these observations do not exclude the possibility of soil-structure interaction effects on the measured recordings. The 5% damped pseudo-spectral accelerations (PSA) from the recorded ground motions compared well to those estimated from the recent NGA-West2 GMPEs. The exceptions are that PSA is under predicted from 1 to 3 seconds at several near fault records due to the velocity pulses and for short periods at Carquinez Bridge where the large

  6. Design of the Digital Satellite Link Interface for a System That Detects the Precursory Electromagnetic Emissions Associated with Earthquakes

    DTIC Science & Technology

    1986-12-01

    earthquake that is likely to occur in a given louality [Ref. 8:p. 1082]. The accumulation law of seismotectonic movement relates the amount of...mechanism - fault creep anomaly - seismic wave velocity - geomagnetic field - telluric (earth) currents - electromagnetic emissions - resistivity of

  7. Rapid estimation of earthquake magnitude from the arrival time of the peak high‐frequency amplitude

    USGS Publications Warehouse

    Noda, Shunta; Yamamoto, Shunroku; Ellsworth, William L.

    2016-01-01

    We propose a simple approach to measure earthquake magnitude M using the time difference (Top) between the body‐wave onset and the arrival time of the peak high‐frequency amplitude in an accelerogram. Measured in this manner, we find that Mw is proportional to 2logTop for earthquakes 5≤Mw≤7, which is the theoretical proportionality if Top is proportional to source dimension and stress drop is scale invariant. Using high‐frequency (>2  Hz) data, the root mean square (rms) residual between Mw and MTop(M estimated from Top) is approximately 0.5 magnitude units. The rms residuals of the high‐frequency data in passbands between 2 and 16 Hz are uniformly smaller than those obtained from the lower‐frequency data. Top depends weakly on epicentral distance, and this dependence can be ignored for distances <200  km. Retrospective application of this algorithm to the 2011 Tohoku earthquake produces a final magnitude estimate of M 9.0 at 120 s after the origin time. We conclude that Top of high‐frequency (>2  Hz) accelerograms has value in the context of earthquake early warning for extremely large events.

  8. Stability assessment of structures under earthquake hazard through GRID technology

    NASA Astrophysics Data System (ADS)

    Prieto Castrillo, F.; Boton Fernandez, M.

    2009-04-01

    This work presents a GRID framework to estimate the vulnerability of structures under earthquake hazard. The tool has been designed to cover the needs of a typical earthquake engineering stability analysis; preparation of input data (pre-processing), response computation and stability analysis (post-processing). In order to validate the application over GRID, a simplified model of structure under artificially generated earthquake records has been implemented. To achieve this goal, the proposed scheme exploits the GRID technology and its main advantages (parallel intensive computing, huge storage capacity and collaboration analysis among institutions) through intensive interaction among the GRID elements (Computing Element, Storage Element, LHC File Catalogue, federated database etc.) The dynamical model is described by a set of ordinary differential equations (ODE's) and by a set of parameters. Both elements, along with the integration engine, are encapsulated into Java classes. With this high level design, subsequent improvements/changes of the model can be addressed with little effort. In the procedure, an earthquake record database is prepared and stored (pre-processing) in the GRID Storage Element (SE). The Metadata of these records is also stored in the GRID federated database. This Metadata contains both relevant information about the earthquake (as it is usual in a seismic repository) and also the Logical File Name (LFN) of the record for its later retrieval. Then, from the available set of accelerograms in the SE, the user can specify a range of earthquake parameters to carry out a dynamic analysis. This way, a GRID job is created for each selected accelerogram in the database. At the GRID Computing Element (CE), displacements are then obtained by numerical integration of the ODE's over time. The resulting response for that configuration is stored in the GRID Storage Element (SE) and the maximum structure displacement is computed. Then, the corresponding

  9. Application of τc*Pd for identifying damaging earthquakes for earthquake early warning

    NASA Astrophysics Data System (ADS)

    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.

  10. St. Louis Area Earthquake Hazards Mapping Project

    USGS Publications Warehouse

    Williams, Robert A.; Steckel, Phyllis; Schweig, Eugene

    2007-01-01

    St. Louis has experienced minor earthquake damage at least 12 times in the past 200 years. Because of this history and its proximity to known active earthquake zones, the St. Louis Area Earthquake Hazards Mapping Project will produce digital maps that show variability of earthquake hazards in the St. Louis area. The maps will be available free via the internet. They can be customized by the user to show specific areas of interest, such as neighborhoods or transportation routes.

  11. Development of magnitude scaling relationship for earthquake early warning system in South Korea

    NASA Astrophysics Data System (ADS)

    Sheen, D.

    2011-12-01

    Seismicity in South Korea is low and magnitudes of recent earthquakes are mostly less than 4.0. However, historical earthquakes of South Korea reveal that many damaging earthquakes had occurred in the Korean Peninsula. To mitigate potential seismic hazard in the Korean Peninsula, earthquake early warning (EEW) system is being installed and will be operated in South Korea in the near future. In order to deliver early warnings successfully, it is very important to develop stable magnitude scaling relationships. In this study, two empirical magnitude relationships are developed from 350 events ranging in magnitude from 2.0 to 5.0 recorded by the KMA and the KIGAM. 1606 vertical component seismograms whose epicentral distances are within 100 km are chosen. The peak amplitude and the maximum predominant period of the initial P wave are used for finding magnitude relationships. The peak displacement of seismogram recorded at a broadband seismometer shows less scatter than the peak velocity of that. The scatters of the peak displacement and the peak velocity of accelerogram are similar to each other. The peak displacement of seismogram differs from that of accelerogram, which means that two different magnitude relationships for each type of data should be developed. The maximum predominant period of the initial P wave is estimated after using two low-pass filters, 3 Hz and 10 Hz, and 10 Hz low-pass filter yields better estimate than 3 Hz. It is found that most of the peak amplitude and the maximum predominant period are estimated within 1 sec after triggering.

  12. Earthquake Hazards.

    ERIC Educational Resources Information Center

    Donovan, Neville

    1979-01-01

    Provides a survey and a review of earthquake activity and global tectonics from the advancement of the theory of continental drift to the present. Topics include: an identification of the major seismic regions of the earth, seismic measurement techniques, seismic design criteria for buildings, and the prediction of earthquakes. (BT)

  13. Analog earthquakes

    SciTech Connect

    Hofmann, R.B.

    1995-09-01

    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.more » A potential use of analog earthquakes is proposed for a high-level nuclear waste (HLW) repository.« less

  14. Earthquake Facts

    MedlinePlus

    ... recordings of large earthquakes, scientists built large spring-pendulum seismometers in an attempt to record the long- ... are moving away from one another. The first “pendulum seismoscope” to measure the shaking of the ground ...

  15. Earthquake watch

    USGS Publications Warehouse

    Hill, M.

    1976-01-01

     When the time comes that earthquakes can be predicted accurately, what shall we do with the knowledge? This was the theme of a November 1975 conference on earthquake warning and response held in San Francisco called by Assistant Secretary of the Interior Jack W. Carlson. Invited were officials of State and local governments from Alaska, California, Hawaii, Idaho, Montana, Nevada, utah, Washington, and Wyoming and representatives of the news media. 

  16. REVERSING CYCLIC ELASTO-PLASTIC DEMANDS ON STRUCTURES DURING STRONG MOTION EARTHQUAKE EXCITATION.

    USGS Publications Warehouse

    Perez, V.; Brady, A.G.; Safak, E.

    1986-01-01

    Using the horizontal components from El Centro 1940, Taft 1952, and 4 accelerograms from the San Fernando earthquake of 2/9/71, the time history of the elasto-plastic displacement response was calculated for oscillators having periods within the range of 1 to 6 s and ductility factors within the range of 3 to 6. The Nth largest peak of the elasto-plastic response (N equals 2,4,8,16), when expressed as a percentage of maximum response (that is, N equals 1), is fairly independent of period within our period range. When considering only plastic peaks occurring, sometimes in a one-directional group of peaks, in the reverse direction from the preceding plastic peak, the amplitude of the Nth reversing plastic peak is similar to the Nth elastic peak, regardless of the ductility factor.

  17. The Electronic Encyclopedia of Earthquakes

    NASA Astrophysics Data System (ADS)

    Benthien, M.; Marquis, J.; Jordan, T.

    2003-12-01

    The Electronic Encyclopedia of Earthquakes is a collaborative project of the Southern California Earthquake Center (SCEC), the Consortia of Universities for Research in Earthquake Engineering (CUREE) and the Incorporated Research Institutions for Seismology (IRIS). This digital library organizes earthquake information online as a partner with the NSF-funded National Science, Technology, Engineering and Mathematics (STEM) Digital Library (NSDL) and the Digital Library for Earth System Education (DLESE). When complete, information and resources for over 500 Earth science and engineering topics will be included, with connections to curricular materials useful for teaching Earth Science, engineering, physics and mathematics. Although conceived primarily as an educational resource, the Encyclopedia is also a valuable portal to anyone seeking up-to-date earthquake information and authoritative technical sources. "E3" is a unique collaboration among earthquake scientists and engineers to articulate and document a common knowledge base with a shared terminology and conceptual framework. It is a platform for cross-training scientists and engineers in these complementary fields and will provide a basis for sustained communication and resource-building between major education and outreach activities. For example, the E3 collaborating organizations have leadership roles in the two largest earthquake engineering and earth science projects ever sponsored by NSF: the George E. Brown Network for Earthquake Engineering Simulation (CUREE) and the EarthScope Project (IRIS and SCEC). The E3 vocabulary and definitions are also being connected to a formal ontology under development by the SCEC/ITR project for knowledge management within the SCEC Collaboratory. The E3 development system is now fully operational, 165 entries are in the pipeline, and the development teams are capable of producing 20 new, fully reviewed encyclopedia entries each month. Over the next two years teams will

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Regional spectral analysis of three moderate earthquakes in Northeastern North America

    USGS Publications Warehouse

    Boatwright, John; Seekins, Linda C.

    2011-01-01

    We analyze Fourier spectra obtained from the horizontal components of broadband and accelerogram data from the 1997 Cap-Rouge, the 2002 Ausable Forks, and the 2005 Rivière-du-Loup earthquakes, recorded by Canadian and American stations sited on rock at hypocentral distances from 23 to 602 km. We check the recorded spectra closely for anomalies that might result from site resonance or source effects. We use Beresnev and Atkinson’s (1997) near-surface velocity structures and Boore and Joyner’s (1997) quarter-wave method to estimate site response at hard- and soft-rock sites. We revise the Street et al. (1975) model for geometrical spreading, adopting a crossover distance of ro=50 km instead of 100 km. We obtain an average attenuation of Q=410±25f0.50±0.03 for S+Lg+surface waves with ray paths in the Appalachian and southeastern Grenville Provinces. We correct the recorded spectra for attenuation and site response to estimate source spectral shape and radiated energy for these three earthquakes and the 1988 M 5.8 Saguenay earthquake. The Brune stress drops range from 130 to 419 bars, and the apparent stresses range from 39 to 63 bars. The corrected source spectral shapes of these earthquakes are somewhat variable for frequencies from 0.2 to 2 Hz, falling slightly below the fitted Brune spectra.

  20. Earthquakes for Kids

    MedlinePlus

    ... across a fault to learn about past earthquakes. Science Fair Projects A GPS instrument measures slow movements of the ground. Become an Earthquake Scientist Cool Earthquake Facts Today in Earthquake History A scientist stands in ...

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Understanding Earthquakes

    ERIC Educational Resources Information Center

    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…

  3. Earthquake Testing

    NASA Technical Reports Server (NTRS)

    1979-01-01

    During NASA's Apollo program, it was necessary to subject the mammoth Saturn V launch vehicle to extremely forceful vibrations to assure the moonbooster's structural integrity in flight. Marshall Space Flight Center assigned vibration testing to a contractor, the Scientific Services and Systems Group of Wyle Laboratories, Norco, California. Wyle-3S, as the group is known, built a large facility at Huntsville, Alabama, and equipped it with an enormously forceful shock and vibration system to simulate the liftoff stresses the Saturn V would encounter. Saturn V is no longer in service, but Wyle-3S has found spinoff utility for its vibration facility. It is now being used to simulate earthquake effects on various kinds of equipment, principally equipment intended for use in nuclear power generation. Government regulations require that such equipment demonstrate its ability to survive earthquake conditions. In upper left photo, Wyle3S is preparing to conduct an earthquake test on a 25ton diesel generator built by Atlas Polar Company, Ltd., Toronto, Canada, for emergency use in a Canadian nuclear power plant. Being readied for test in the lower left photo is a large circuit breaker to be used by Duke Power Company, Charlotte, North Carolina. Electro-hydraulic and electro-dynamic shakers in and around the pit simulate earthquake forces.

  4. Connecting slow earthquakes to huge earthquakes.

    PubMed

    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.

  5. The 13 January 2001 El Salvador earthquake: A multidata analysis

    NASA Astrophysics Data System (ADS)

    ValléE, Martin; Bouchon, Michel; Schwartz, Susan Y.

    2003-04-01

    On 13 January 2001, a large normal faulting intermediate depth event (Mw = 7.7) occurred 40 km off the El Salvadorian coast (Central America). We analyze this earthquake using teleseismic, regional, and local data. We first build a kinematic source model by simultaneously inverting P and SH displacement waveforms and source time functions derived from surface waves using an empirical Green's function analysis. In an attempt to discriminate between the two nodal planes (30° trenchward dipping and 60° landward dipping), we perform identical inversions using both possible fault planes. After relocating the hypocentral depth at 54 km, we retrieve the kinematic features of the rupture using a combination of the Neighborhood algorithm of [1999] and the Simplex method allowing for variable rupture velocity and slip. We find updip rupture propagation yielding a centroid depth around 47 km for both assumed fault planes with a larger variance reduction obtained using the 60° landward dipping nodal plane. We test the two possible fault models using regional broadband data and near-field accelerograms provided by [2001]. Near-field data confirm that the steeper landward dipping nodal plane is preferred. Rupture propagated mostly updip and to the northwest, resulting in a main moment release zone of approximately 25 km × 50 km with an average slip of ˜3.5 m. The large slip occurs near the interplate interface at a location where the slab steepens dip significantly. The occurrence of this event is well-explained by bending of the subducting plate.

  6. Defeating Earthquakes

    NASA Astrophysics Data System (ADS)

    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

  7. Acceleration spectra for subduction zone earthquakes

    USGS Publications Warehouse

    Boatwright, J.; Choy, G.L.

    1989-01-01

    We estimate the source spectra of shallow earthquakes from digital recordings of teleseismic P wave groups, that is, P+pP+sP, by making frequency dependent corrections for the attenuation and for the interference of the free surface. The correction for the interference of the free surface assumes that the earthquake radiates energy from a range of depths. We apply this spectral analysis to a set of 12 subduction zone earthquakes which range in size from Ms = 6.2 to 8.1, obtaining corrected P wave acceleration spectra on the frequency band from 0.01 to 2.0 Hz. Seismic moment estimates from surface waves and normal modes are used to extend these P wave spectra to the frequency band from 0.001 to 0.01 Hz. The acceleration spectra of large subduction zone earthquakes, that is, earthquakes whose seismic moments are greater than 1027 dyn cm, exhibit intermediate slopes where u(w)???w5/4 for frequencies from 0.005 to 0.05 Hz. For these earthquakes, spectral shape appears to be a discontinuous function of seismic moment. Using reasonable assumptions for the phase characteristics, we transform the spectral shape observed for large earthquakes into the time domain to fit Ekstrom's (1987) moment rate functions for the Ms=8.1 Michoacan earthquake of September 19, 1985, and the Ms=7.6 Michoacan aftershock of September 21, 1985. -from Authors

  8. It's Our Fault: better defining earthquake risk in Wellington, New Zealand

    NASA Astrophysics Data System (ADS)

    Van Dissen, R.; Brackley, H. L.; Francois-Holden, C.

    2012-12-01

    increasing the region's resilience to earthquakes. We present latest results on ground motion simulations for large plate interface earthquakes under Wellington in terms of response spectra and acceleration time histories. We derive realistic broadband accelerograms based on a stochastic modelling technique. First we characterise the potential interface rupture area based on previous geodetically-derived estimates interface of slip deficit. Then, we entertain a suitable range of source parameters, including various rupture areas, moment magnitudes, stress drops, slip distributions and rupture propagation directions. The resulting rupture scenarios all produce long duration shaking, and peak ground accelerations that, typically, range between 0.2-0.7 g in Wellington city. Many of these scenarios also produce long period motions that are currently not captured by the current NZ design spectra.

  9. Seismological investigation of earthquakes in the New Madrid seismic zone and the northeastern extent of the New Madrid seismic zone: Final report, September 1981-December 1986

    SciTech Connect

    Herrmann, R.B.; Taylor, K.; Nguyen, B.

    1988-07-01

    Earthquake activity in the Central Mississippi Valley has been monitored by an eight station seismograph network in the Wabash River Valley of southeastern Illinois and by a six station seismograph network in the New Madrid seismic zone. This network is a major component of a larger network in the region, jointly sponsored by the NRC, USGS, universities and states. During the time period of the contract, October 1981 through December 1986, 1206 earthquakes were located in the Central Mississippi Valley, of which 808 were in the New Madrid, Missouri area. Significant earthquakes studied in detail occurred in northeastern Ohio onmore » January 31, 1986 and in southeastern Illinois on June 10, 1987. Focal mechanisms have been calculated for the 10 June 1987 southern Illinois earthquake using both P-wave first motions and long-period surface-wave spectral amplitude data. The long-period surface-wave and strong ground motion accelerogram recordings of the January 3, 1986, northeastern Ohio earthquake were used to estimate the focal mechanism and source time function of the source.reverse arrow« less

  10. Pattern of ground deformation in Kathmandu valley during 2015 Gorkha Earthquake, central Nepal

    NASA Astrophysics Data System (ADS)

    Ghimire, S.; Dwivedi, S. K.; Acharya, K. K.

    2016-12-01

    The 25th April 2015 Gorkha Earthquake (Mw=7.8) epicentered at Barpak along with thousands of aftershocks released seismic moment nearly equivalent to an 8.0 Magnitude earthquake rupturing a 150km long fault segment. Although Kathmandu valley was supposed to be severely devastated by such major earthquake, post earthquake scenario is completely different. The observed destruction is far less than anticipated as well as the spatial pattern is different than expected. This work focuses on the behavior of Kathmandu valley sediments during the strong shaking by the 2015 Gorkha Earthquake. For this purpose spatial pattern of destruction is analyzed at heavily destructed sites. To understand characteristics of subsurface soil 2D-MASW survey was carried out using a 24-channel seismograph system. An accellerogram recorded by Nepal Seismological Center was analyzed to characterize the strong ground motion. The Kathmandu valley comprises fluvio-lacustrine deposit with gravel, sand, silt and clay along with few exposures of basement rocks within the sediments. The observations show systematic repetition of destruction at an average interval of 2.5km mostly in sand, silt and clay dominated formations. Results of 2D-MASW show the sites of destruction are characterized by static deformation of soil (liquefaction and southerly dipping cracks). Spectral analysis of the accelerogram indicates maximum power associated with frequency of 1.0Hz. The result of this study explains the observed spatial pattern of destruction in Kathmandu valley. This is correlated with the seismic energy associated with the frequency of 1Hz, which generates an average wavelength of 2.5km with an average S-wave velocity of 2.5km/s. The cumulative effect of dominant frequency and associated wavelength resulted in static deformation of surface soil layers at an average interval of 2.5km. This phenomenon clearly describes the reason for different scenario than that was anticipated in Kathmandu valley.

  11. Identification of Deep Earthquakes

    DTIC Science & Technology

    2010-09-01

    discriminants that will reliably separate small, crustal earthquakes (magnitudes less than about 4 and depths less than about 40 to 50 km) from small...characteristics on discrimination plots designed to separate nuclear explosions from crustal earthquakes. Thus, reliably flagging these small, deep events is...Further, reliably identifying subcrustal earthquakes will allow us to eliminate deep events (previously misidentified as crustal earthquakes) from

  12. Accessing northern California earthquake data via Internet

    NASA Astrophysics Data System (ADS)

    Romanowicz, Barbara; Neuhauser, Douglas; Bogaert, Barbara; Oppenheimer, David

    The Northern California Earthquake Data Center (NCEDC) provides easy access to central and northern California digital earthquake data. It is located at the University of California, Berkeley, and is operated jointly with the U.S. Geological Survey (USGS) in Menlo Park, Calif., and funded by the University of California and the National Earthquake Hazard Reduction Program. It has been accessible to users in the scientific community through Internet since mid-1992.The data center provides an on-line archive for parametric and waveform data from two regional networks: the Northern California Seismic Network (NCSN) operated by the USGS and the Berkeley Digital Seismic Network (BDSN) operated by the Seismographic Station at the University of California, Berkeley.

  13. Early Warning for Large Magnitude Earthquakes: Is it feasible?

    NASA Astrophysics Data System (ADS)

    Zollo, A.; Colombelli, S.; Kanamori, H.

    2011-12-01

    The mega-thrust, Mw 9.0, 2011 Tohoku earthquake has re-opened the discussion among the scientific community about the effectiveness of Earthquake Early Warning (EEW) systems, when applied to such large events. Many EEW systems are now under-testing or -development worldwide and most of them are based on the real-time measurement of ground motion parameters in a few second window after the P-wave arrival. Currently, we are using the initial Peak Displacement (Pd), and the Predominant Period (τc), among other parameters, to rapidly estimate the earthquake magnitude and damage potential. A well known problem about the real-time estimation of the magnitude is the parameter saturation. Several authors have shown that the scaling laws between early warning parameters and magnitude are robust and effective up to magnitude 6.5-7; the correlation, however, has not yet been verified for larger events. The Tohoku earthquake occurred near the East coast of Honshu, Japan, on the subduction boundary between the Pacific and the Okhotsk plates. The high quality Kik- and K- networks provided a large quantity of strong motion records of the mainshock, with a wide azimuthal coverage both along the Japan coast and inland. More than 300 3-component accelerograms have been available, with an epicentral distance ranging from about 100 km up to more than 500 km. This earthquake thus presents an optimal case study for testing the physical bases of early warning and to investigate the feasibility of a real-time estimation of earthquake size and damage potential even for M > 7 earthquakes. In the present work we used the acceleration waveform data of the main shock for stations along the coast, up to 200 km epicentral distance. We measured the early warning parameters, Pd and τc, within different time windows, starting from 3 seconds, and expanding the testing time window up to 30 seconds. The aim is to verify the correlation of these parameters with Peak Ground Velocity and Magnitude

  14. Effect of baseline corrections on response spectra for two recordings of the 1999 Chi-Chi, Taiwan, earthquake

    USGS Publications Warehouse

    Boore, David M.

    1999-01-01

    Displacements derived from the accelerogram recordings of the 1999 Chi-Chi, Taiwan earthquake at stations TCU078 and TCU129 show drifts when only a simple baseline derived from the pre-event portion of the record is removed from the records. The appearance of the velocity and displacement records suggests that changes in the zero-level of the acceleration are responsible for these drifts. The source of the shifts in zero-level are unknown, but might include tilts in the instruments or the response of the instruments to strong shaking. This note illustrates the effect on the velocity, displacement, and response spectra of several schemes for accounting for these baseline shifts. The most important conclusion for earthquake engineering purposes is that the response spectra for periods less than about 20 sec are unaffected by the baseline correction. The results suggest, however, that staticdisplac ements estimated from the instruments should be used with caution. Although limited to the analysis of only two recordings, the results may have more general significance both for the many other recordings of this earthquake and for data that will be obtained in the future from similar high-quality accelerograph networks now being installed or soon to be installed in many parts of the world.

  15. Effect of baseline corrections on displacements and response spectra for several recordings of the 1999 Chi-Chi, Taiwan, earthquake

    USGS Publications Warehouse

    Boore, D.M.

    2001-01-01

    Displacements derived from many of the accelerogram recordings of the 1999 Chi-Chi, Taiwan, earthquake show drifts when only a simple baseline derived from the pre-event portion of the record is removed from the records. The appearance of the velocity and displacement records suggests that changes in the zero level of the acceleration are responsible for these drifts. The source of the shifts in zero level are unknown, but in at least one case it is almost certainly due to tilting of the ground. This article illustrates the effect on the ground velocity, ground displacement, and response spectra of several schemes for accounting for these baseline shifts. A wide range of final displacements can be obtained for various choices of baseline correction, and comparison with nearby GPS stations (none of which are colocated with the accelerograph stations) do not help in choosing the appropriate baseline correction. The results suggest that final displacements estimated from the records should be used with caution. The most important conclusion for earthquake engineering purposes, however, is that the response spectra for periods less than about 20 sec are usually unaffected by the baseline correction. Although limited to the analysis of only a small number of recordings, the results may have more general significance both for the many other recordings of this earthquake and for data that will be obtained in the future from similar high-quality accelerograph networks now being installed or soon to be installed in many parts of the world.

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

    USGS Publications Warehouse

    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

  17. Earthquakes: Predicting the unpredictable?

    USGS Publications Warehouse

    Hough, Susan E.

    2005-01-01

    The earthquake prediction pendulum has swung from optimism in the 1970s to rather extreme pessimism in the 1990s. Earlier work revealed evidence of possible earthquake precursors: physical changes in the planet that signal that a large earthquake is on the way. Some respected earthquake scientists argued that earthquakes are likewise fundamentally unpredictable. The fate of the Parkfield prediction experiment appeared to support their arguments: A moderate earthquake had been predicted along a specified segment of the central San Andreas fault within five years of 1988, but had failed to materialize on schedule. At some point, however, the pendulum began to swing back. Reputable scientists began using the "P-word" in not only polite company, but also at meetings and even in print. If the optimism regarding earthquake prediction can be attributed to any single cause, it might be scientists' burgeoning understanding of the earthquake cycle.

  18. Earthquakes: hydrogeochemical precursors

    USGS Publications Warehouse

    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.

  19. Redefining Earthquakes and the Earthquake Machine

    ERIC Educational Resources Information Center

    Hubenthal, Michael; Braile, Larry; Taber, John

    2008-01-01

    The Earthquake Machine (EML), a mechanical model of stick-slip fault systems, can increase student engagement and facilitate opportunities to participate in the scientific process. This article introduces the EML model and an activity that challenges ninth-grade students' misconceptions about earthquakes. The activity emphasizes the role of models…

  20. Important Earthquake Engineering Resources

    Science.gov Websites

    PEER logo Pacific Earthquake Engineering Research Center home about peer news events research Engineering Resources Site Map Search Important Earthquake Engineering Resources - American Concrete Institute Motion Observation Systems (COSMOS) - Consortium of Universities for Research in Earthquake Engineering

  1. 2016 National Earthquake Conference

    Science.gov Websites

    Thank you to our Presenting Sponsor, California Earthquake Authority. What's New? What's Next ? What's Your Role in Building a National Strategy? The National Earthquake Conference (NEC) is a , state government leaders, social science practitioners, U.S. State and Territorial Earthquake Managers

  2. Can We Predict Earthquakes?

    ScienceCinema

    Johnson, Paul

    2018-01-16

    The only thing we know for sure about earthquakes is that one will happen again very soon. Earthquakes pose a vital yet puzzling set of research questions that have confounded scientists for decades, but new ways of looking at seismic information and innovative laboratory experiments are offering tantalizing clues to what triggers earthquakes — and when.

  3. Earthquake and Schools. [Videotape].

    ERIC Educational Resources Information Center

    Federal Emergency Management Agency, Washington, DC.

    Designing schools to make them more earthquake resistant and protect children from the catastrophic collapse of the school building is discussed in this videotape. It reveals that 44 of the 50 U.S. states are vulnerable to earthquake, but most schools are structurally unprepared to take on the stresses that earthquakes exert. The cost to the…

  4. Children's Ideas about Earthquakes

    ERIC Educational Resources Information Center

    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…

  5. Operational earthquake forecasting can enhance earthquake preparedness

    USGS Publications Warehouse

    Jordan, T.H.; Marzocchi, W.; Michael, A.J.; Gerstenberger, M.C.

    2014-01-01

    We cannot yet predict large earthquakes in the short term with much reliability and skill, but the strong clustering exhibited in seismic sequences tells us that earthquake probabilities are not constant in time; they generally rise and fall over periods of days to years in correlation with nearby seismic activity. Operational earthquake forecasting (OEF) is the dissemination of authoritative information about these time‐dependent probabilities to help communities prepare for potentially destructive earthquakes. The goal of OEF is to inform the decisions that people and organizations must continually make to mitigate seismic risk and prepare for potentially destructive earthquakes on time scales from days to decades. To fulfill this role, OEF must provide a complete description of the seismic hazard—ground‐motion exceedance probabilities as well as short‐term rupture probabilities—in concert with the long‐term forecasts of probabilistic seismic‐hazard analysis (PSHA).

  6. Magnitude Estimation for the 2011 Tohoku-Oki Earthquake Based on Ground Motion Prediction Equations

    NASA Astrophysics Data System (ADS)

    Eshaghi, Attieh; Tiampo, Kristy F.; Ghofrani, Hadi; Atkinson, Gail M.

    2015-08-01

    This study investigates whether real-time strong ground motion data from seismic stations could have been used to provide an accurate estimate of the magnitude of the 2011 Tohoku-Oki earthquake in Japan. Ultimately, such an estimate could be used as input data for a tsunami forecast and would lead to more robust earthquake and tsunami early warning. We collected the strong motion accelerograms recorded by borehole and free-field (surface) Kiban Kyoshin network stations that registered this mega-thrust earthquake in order to perform an off-line test to estimate the magnitude based on ground motion prediction equations (GMPEs). GMPEs for peak ground acceleration and peak ground velocity (PGV) from a previous study by Eshaghi et al. in the Bulletin of the Seismological Society of America 103. (2013) derived using events with moment magnitude ( M) ≥ 5.0, 1998-2010, were used to estimate the magnitude of this event. We developed new GMPEs using a more complete database (1998-2011), which added only 1 year but approximately twice as much data to the initial catalog (including important large events), to improve the determination of attenuation parameters and magnitude scaling. These new GMPEs were used to estimate the magnitude of the Tohoku-Oki event. The estimates obtained were compared with real time magnitude estimates provided by the existing earthquake early warning system in Japan. Unlike the current operational magnitude estimation methods, our method did not saturate and can provide robust estimates of moment magnitude within ~100 s after earthquake onset for both catalogs. It was found that correcting for average shear-wave velocity in the uppermost 30 m () improved the accuracy of magnitude estimates from surface recordings, particularly for magnitude estimates of PGV (Mpgv). The new GMPEs also were used to estimate the magnitude of all earthquakes in the new catalog with at least 20 records. Results show that the magnitude estimate from PGV values using

  7. Crowdsourced earthquake early warning

    PubMed Central

    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. PMID:26601167

  8. Crowdsourced earthquake early warning.

    PubMed

    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

    2015-04-01

    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 M w (moment magnitude) 7 earthquake on California's Hayward fault, and real data from the M w 9 Tohoku-oki earthquake, we demonstrate that EEW could be achieved via crowdsourcing.

  9. Crowdsourced earthquake early warning

    USGS Publications Warehouse

    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.

  10. Features of tuned mass damper behavior under strong earthquakes

    NASA Astrophysics Data System (ADS)

    Nesterova, Olga; Uzdin, Alexander; Fedorova, Maria

    2018-05-01

    Plastic deformations, cracks and destruction of structure members appear in the constructions under strong earthquakes. Therefore constructions are characterized by a nonlinear deformation diagram. Two types of construction non-linearity are considered in the paper. The first type of nonlinearity is elastoplastic one. In this case, plastic deformations occur in the structural elements, and when the element is unloaded, its properties restores. Among such diagrams are the Prandtl diagram, the Prandtl diagram with hardening, the Ramberg-Osgood diagram and others. For systems with such nonlinearity there is an amplitude-frequency characteristic and resonance oscillation frequencies. In this case one can pick up the most dangerous accelerograms for the construction. The second type of nonlinearity is nonlinearity with degrading rigidity and dependence of behavior on the general loading history. The Kirikov-Amankulov model is one of such ones. Its behavior depends on the maximum displacement in the stress history. Such systems do not have gain frequency characteristic and resonance frequency. The period of oscillation of such system is increasing during the system loading, and the system eigen frequency decreases to zero at the time of collapse. In the cases under consideration, when investigating the system with MD behavior, the authors proposed new efficiency criteria. These include the work of plastic deformation forces for the first type of nonlinearity, which determines the possibility of progressive collapse or low cycle fatigue of the structure members. The period of system oscillations and the time to collapse of the structural support members are the criterion for systems with degrading rigidity. In the case of non-linear system behavior, the efficiency of MD application decreases, because the fundamental structure period is reduced because of structure damages and the MD will be rebound from the blanking regime. However, the MD using can significantly reduce

  11. Topographic changes and their driving factors after 2008 Wenchuan Earthquake

    NASA Astrophysics Data System (ADS)

    Li, C.; Wang, M.; Xie, J.; Liu, K.

    2017-12-01

    The Wenchuan Ms 8.0 Earthquake caused topographic change in the stricken areas because of the formation of numerous coseismic landslides. The emergence of new landslides and debris flows and movement of loose materials under the driving force of heavy rainfall could further shape the local topography. Dynamic topographic changes in mountainous areas stricken by major earthquakes have a strong linkage to the development and occurrence of secondary disasters. However, little attention has been paid to continuously monitoring mountain environment change after such earthquakes. A digital elevation model (DEM) is the main feature of the terrain surface, in our research, we extracted DEM in 2013 and 2015 of a typical mountainous area severely impacted by the 2008 Wenchuan earthquake from the ZY-3 stereo pair images with validation by field measurement. Combined with the elevation dataset in 2002 and 2010, we quantitatively assessed elevation changes in different years and qualitatively analyzed spatiotemporal variation of the terrain and mass movement across the study area. The results show that the earthquake stricken area experienced substantial elevation changes caused by seismic forces and subsequent rainfalls. Meanwhile, deposits after the earthquake are mainly accumulated on the river-channels and mountain ridges and deep gullies which increase the risk of other geo-hazards. And the heavy rainfalls after the earthquake have become the biggest driver of elevation reduction, which overwhelmed elevation increase during the major earthquake. Our study provided a better understanding of subsequent hazards and risks faced by residents and communities stricken by major earthquakes.

  12. Extreme magnitude earthquakes and their economical impact: The Mexico City case

    NASA Astrophysics Data System (ADS)

    Chavez, M.; Mario, C.

    2005-12-01

    The consequences (estimated by the human and economical losses) of the recent occurrence (worldwide) of extreme magnitude (for the region under consideration) earthquakes, such as the 19 09 1985 in Mexico (Ritchter magnitude Ms 8.1, moment magnitude Mw 8.01), or the one in Indonesia of the 26 12 2004 (Ms 9.4, Mw 9.3), stress the importance of performing seismic hazard analysis that, specifically, incorporate this possibility. Herewith, we present and apply a methodology, based on plausible extreme seismic scenarios and the computation of their associated synthetic accelerograms, to estimate the seismic hazard on Mexico City (MC) stiff and compressible surficial soils. The uncertainties about the characteristics of the potential finite seismic sources, as well as those related to the dynamic properties of MC compressible soils are taken into account. The economic consequences (i.e. the seismic risk = seismic hazard x economic cost) implicit in the seismic coefficients proposed in MC seismic Codes before (1976) and after the 1985 earthquake (2004) are analyzed. Based on the latter and on an acceptable risk criterion, a maximum seismic coefficient (MSC) of 1.4g (g = 9.81m/s2) of the elastic acceleration design spectra (5 percent damping), which has a probability of exceedance of 2.4 x 10-4, seems to be appropriate for analyzing the seismic behavior of infrastructure located on MC compressible soils, if extreme Mw 8.5 subduction thrust mechanism earthquakes (similar to the one occurred on 19 09 1985 with an observed, equivalent, MSC of 1g) occurred in the next 50 years.

  13. A Mw 6.3 earthquake scenario in the city of Nice (southeast France): ground motion simulations

    NASA Astrophysics Data System (ADS)

    Salichon, Jérome; Kohrs-Sansorny, Carine; Bertrand, Etienne; Courboulex, Françoise

    2010-07-01

    The southern Alps-Ligurian basin junction is one of the most seismically active zone of the western Europe. A constant microseismicity and moderate size events (3.5 < M < 5) are regularly recorded. The last reported historical event took place in February 1887 and reached an estimated magnitude between 6 and 6.5, causing human losses and extensive damages (intensity X, Medvedev-Sponheuer-Karnik). Such an event, occurring nowadays, could have critical consequences given the high density of population living on the French and Italian Riviera. We study the case of an offshore Mw 6.3 earthquake located at the place where two moderate size events (Mw 4.5) occurred recently and where a morphotectonic feature has been detected by a bathymetric survey. We used a stochastic empirical Green’s functions (EGFs) summation method to produce a population of realistic accelerograms on rock and soil sites in the city of Nice. The ground motion simulations are calibrated on a rock site with a set of ground motion prediction equations (GMPEs) in order to estimate a reasonable stress-drop ratio between the February 25th, 2001, Mw 4.5, event taken as an EGF and the target earthquake. Our results show that the combination of the GMPEs and EGF techniques is an interesting tool for site-specific strong ground motion estimation.

  14. Investigating landslides caused by earthquakes - A historical review

    USGS Publications Warehouse

    Keefer, D.K.

    2002-01-01

    Post-earthquake field investigations of landslide occurrence have provided a basis for understanding, evaluating, and mapping the hazard and risk associated with earthquake-induced landslides. This paper traces the historical development of knowledge derived from these investigations. Before 1783, historical accounts of the occurrence of landslides in earthquake are typically so incomplete and vague that conclusions based on these accounts are of limited usefulness. For example, the number of landslides triggered by a given event is almost always greatly underestimated. The first formal, scientific post-earthquake investigation that included systematic documentation of the landslides was undertaken in the Calabria region of Italy after the 1783 earthquake swarm. From then until the mid-twentieth century, the best information on earthquake-induced landslides came from a succession of post-earthquake investigations largely carried out by formal commissions that undertook extensive ground-based field studies. Beginning in the mid-twentieth century, when the use of aerial photography became widespread, comprehensive inventories of landslide occurrence have been made for several earthquakes in the United States, Peru, Guatemala, Italy, El Salvador, Japan, and Taiwan. Techniques have also been developed for performing "retrospective" analyses years or decades after an earthquake that attempt to reconstruct the distribution of landslides triggered by the event. The additional use of Geographic Information System (GIS) processing and digital mapping since about 1989 has greatly facilitated the level of analysis that can applied to mapped distributions of landslides. Beginning in 1984, synthesis of worldwide and national data on earthquake-induced landslides have defined their general characteristics and relations between their occurrence and various geologic and seismic parameters. However, the number of comprehensive post-earthquake studies of landslides is still

  15. The August 1st, 2014 ( M w 5.3) Moderate Earthquake: Evidence for an Active Thrust Fault in the Bay of Algiers (Algeria)

    NASA Astrophysics Data System (ADS)

    Benfedda, A.; Abbes, K.; Bouziane, D.; Bouhadad, Y.; Slimani, A.; Larbes, S.; Haddouche, D.; Bezzeghoud, M.

    2017-03-01

    On August 1st, 2014, a moderate-sized earthquake struck the capital city of Algiers at 05:11:17.6 (GMT+1). The earthquake caused the death of six peoples and injured 420, mainly following a panic movement among the population. Following the main shock, we surveyed the aftershock activity using a portable seismological network (short period), installed from August 2nd, 2014 to August 21st, 2015. In this work, first, we determined the main shock epicenter using the accelerograms recorded by the Algerian accelerograph network (under the coordination of the National Center of Applied Research in Earthquake Engineering-CGS). We calculated the focal mechanism of the main shock, using the inversion of the accelerograph waveforms in displacement that provides a reverse fault with a slight right-lateral component of slip and a compression axis striking NNW-SSE. The obtained scalar seismic moment ( M o = 1.25 × 1017 Nm) corresponds to a moment magnitude of M w = 5.3. Second, the analysis of the obtained aftershock swarm, of the survey, suggests an offshore ENE-WSW, trending and NNW dipping, causative active fault in the bay of Algiers, which may likely correspond to an offshore unknown segment of the Sahel active fault.

  16. Missing great earthquakes

    USGS Publications Warehouse

    Hough, Susan E.

    2013-01-01

    The occurrence of three earthquakes with moment magnitude (Mw) greater than 8.8 and six earthquakes larger than Mw 8.5, since 2004, has raised interest in the long-term global rate of great earthquakes. Past studies have focused on the analysis of earthquakes since 1900, which roughly marks the start of the instrumental era in seismology. Before this time, the catalog is less complete and magnitude estimates are more uncertain. Yet substantial information is available for earthquakes before 1900, and the catalog of historical events is being used increasingly to improve hazard assessment. Here I consider the catalog of historical earthquakes and show that approximately half of all Mw ≥ 8.5 earthquakes are likely missing or underestimated in the 19th century. I further present a reconsideration of the felt effects of the 8 February 1843, Lesser Antilles earthquake, including a first thorough assessment of felt reports from the United States, and show it is an example of a known historical earthquake that was significantly larger than initially estimated. The results suggest that incorporation of best available catalogs of historical earthquakes will likely lead to a significant underestimation of seismic hazard and/or the maximum possible magnitude in many regions, including parts of the Caribbean.

  17. Prototype operational earthquake prediction system

    USGS Publications Warehouse

    Spall, Henry

    1986-01-01

    An objective if the U.S. Earthquake Hazards Reduction Act of 1977 is to introduce into all regions of the country that are subject to large and moderate earthquakes, systems for predicting earthquakes and assessing earthquake risk. In 1985, the USGS developed for the Secretary of the Interior a program for implementation of a prototype operational earthquake prediction system in southern California.

  18. Earthquakes and faults in southern California (1970-2010)

    USGS Publications Warehouse

    Sleeter, Benjamin M.; Calzia, James P.; Walter, Stephen R.

    2012-01-01

    The map depicts both active and inactive faults and earthquakes magnitude 1.5 to 7.3 in southern California (1970–2010). The bathymetry was generated from digital files from the California Department of Fish And Game, Marine Region, Coastal Bathymetry Project. Elevation data are from the U.S. Geological Survey National Elevation Database. Landsat satellite image is from fourteen Landsat 5 Thematic Mapper scenes collected between 2009 and 2010. Fault data are reproduced with permission from 2006 California Geological Survey and U.S. Geological Survey data. The earthquake data are from the U.S. Geological Survey National Earthquake Information Center.

  19. Earthquake Analysis (EA) Software for The Earthquake Observatories

    NASA Astrophysics Data System (ADS)

    Yanik, K.; Tezel, T.

    2009-04-01

    There are many software that can used for observe the seismic signals and locate the earthquakes, but some of them commercial and has technical support. For this reason, many seismological observatories developed and use their own seismological software packets which are convenient with their seismological network. In this study, we introduce our software which has some capabilities that it can read seismic signals and process and locate the earthquakes. This software is used by the General Directorate of Disaster Affairs Earthquake Research Department Seismology Division (here after ERD) and will improve according to the new requirements. ERD network consist of 87 seismic stations that 63 of them were equipped with 24 bite digital Guralp CMG-3T, 16 of them with analogue short period S-13-Geometrics and 8 of them 24 bite digital short period S-13j-DR-24 Geometrics seismometers. Data is transmitted with satellite from broadband stations, whereas leased line used from short period stations. Daily data archive capacity is 4 GB. In big networks, it is very important that observe the seismic signals and locate the earthquakes as soon as possible. This is possible, if they use software which was developed considering their network properties. When we started to develop a software for big networks as our, we recognized some realities that all known seismic format data should be read without any convert process, observing of the only selected stations and do this on the map directly, add seismic files with import command, establishing relation between P and S phase readings and location solutions, store in database and entering to the program with user name and password. In this way, we can prevent data disorder and repeated phase readings. There are many advantages, when data store on the database proxies. These advantages are easy access to data from anywhere using ethernet, publish the bulletin and catalogues using website, easily sending of short message (sms) and e

  20. Measuring the size of an earthquake

    USGS Publications Warehouse

    Spence, W.; Sipkin, S.A.; Choy, G.L.

    1989-01-01

    Today, state-of-the-art seismic systems transmit data from the seismograph via telephone line and satellite directly to a central digital computer. A preliminary location, depth-of-focus, and magntidue can now be obtained within minutes of the onset of an earthquake. The only limiting factor is how long the seismic wave stake to travel from the epicenter to the stations-usually less than 10 minutes. 

  1. Measuring the size of an earthquake

    USGS Publications Warehouse

    Spence, William; Sipkin, Stuart A.; Choy, George L.

    1989-01-01

    Today, state-of-the-art seismic systems transmit data from the seismograph via telephone line and satellite directly to a central digital computer. A preliminary location, depth-of-focus, and magnitude can now be obtained within minutes of onset of an earthquake.  The only limiting factor is how long the seismic waves take to travel from the epicenter to the stations--usually less than 10 minutes.

  2. Earthquakes: Risk, Monitoring, Notification, and Research

    DTIC Science & Technology

    2007-02-02

    Global Seismic Network (GSN). The GSN is a system of broadband digital seismographs arrayed around the globe and designed to collect high-quality...39 states face some risk from earthquakes. Seismic hazards are greatest in the western United States, particularly California, Alaska, Washington...Oregon, and Hawaii. The Rocky Mountain region, a portion of the central United States known as the New Madrid Seismic Zone, and portions of the eastern

  3. Region-specific S-wave attenuation for earthquakes in northwestern Iran

    NASA Astrophysics Data System (ADS)

    Heidari, Reza; Mirzaei, Noorbakhsh

    2017-11-01

    In this study, continuous wavelet transform is applied to estimate the frequency-dependent quality factor of shear waves, Q S , in northwestern Iran. The dataset used in this study includes velocigrams of more than 50 events with magnitudes between 4.0 and 6.5, which have occurred in the study area. The CWT-based method shows a high-resolution technique for the estimation of S-wave frequency-dependent attenuation. The quality factor values are determined in the form of a power law as Q S ( f) = (147 ± 16) f 0.71 ± 0.02 and (126 ± 12) f 0.73 ± 0.02 for vertical and horizontal components, respectively, where f is between 0.9 and 12 Hz. Furthermore, in order to verify the reliability of the suggested Q S estimator method, an additional test is performed by using accelerograms of Ahar-Varzaghan dual earthquakes on August 11, 2012, of moment magnitudes 6.4 and 6.3 and their aftershocks. Results indicate that the estimated Q S values from CWT-based method are not very sensitive to the numbers and types of waveforms used (velocity or acceleration).

  4. Earthquakes in Alaska

    USGS Publications Warehouse

    Haeussler, Peter J.; Plafker, George

    1995-01-01

    Earthquake risk is high in much of the southern half of Alaska, but it is not the same everywhere. This map shows the overall geologic setting in Alaska that produces earthquakes. The Pacific plate (darker blue) is sliding northwestward past southeastern Alaska and then dives beneath the North American plate (light blue, green, and brown) in southern Alaska, the Alaska Peninsula, and the Aleutian Islands. Most earthquakes are produced where these two plates come into contact and slide past each other. Major earthquakes also occur throughout much of interior Alaska as a result of collision of a piece of crust with the southern margin.

  5. Earthquakes, November-December 1973

    USGS Publications Warehouse

    Person, W.J.

    1974-01-01

    Other parts of the world suffered fatalities and significant damage from earthquakes. In Iran, an earthquake killed one person, injured many, and destroyed a number of homes. Earthquake fatalities also occurred in the Azores and in Algeria. 

  6. Linking giant earthquakes with the subduction of oceanic fracture zones

    NASA Astrophysics Data System (ADS)

    Landgrebe, T. C.; Müller, R. D.; EathByte Group

    2011-12-01

    Giant subduction earthquakes are known to occur in areas not previously identified as prone to high seismic risk. This highlights the need to better identify subduction zone segments potentially dominated by relatively long (up to 1000 years and more) recurrence times of giant earthquakes. Global digital data sets represent a promising source of information for a multi-dimensional earthquake hazard analysis. We combine the NGDC global Significant Earthquakes database with a global strain rate map, gridded ages of the ocean floor, and a recently produced digital data set for oceanic fracture zones, major aseismic ridges and volcanic chains to investigate the association of earthquakes as a function of magnitude with age of the downgoing slab and convergence rates. We use a so-called Top-N recommendation method, a technology originally developed to search, sort, classify, and filter very large and often statistically skewed data sets on the internet, to analyse the association of subduction earthquakes sorted by magnitude with key parameters. The Top-N analysis is used to progressively assess how strongly particular "tectonic niche" locations (e.g. locations along subduction zones intersected with aseismic ridges or volcanic chains) are associated with sets of earthquakes in sorted order in a given magnitude range. As the total number N of sorted earthquakes is increased, by progressively including smaller-magnitude events, the so-called recall is computed, defined as the number of Top-N earthquakes associated with particular target areas divided by N. The resultant statistical measure represents an intuitive description of the effectiveness of a given set of parameters to account for the location of significant earthquakes on record. We use this method to show that the occurrence of great (magnitude ≥ 8) earthquakes on overriding plate segments is strongly biased towards intersections of oceanic fracture zones with subduction zones. These intersection regions are

  7. Global Instrumental Seismic Catalog: earthquake relocations for 1900-present

    NASA Astrophysics Data System (ADS)

    Villasenor, A.; Engdahl, E.; Storchak, D. A.; Bondar, I.

    2010-12-01

    We present the current status of our efforts to produce a set of homogeneous earthquake locations and improved focal depths towards the compilation of a Global Catalog of instrumentally recorded earthquakes that will be complete down to the lowest magnitude threshold possible on a global scale and for the time period considered. This project is currently being carried out under the auspices of GEM (Global Earthquake Model). The resulting earthquake catalog will be a fundamental dataset not only for earthquake risk modeling and assessment on a global scale, but also for a large number of studies such as global and regional seismotectonics; the rupture zones and return time of large, damaging earthquakes; the spatial-temporal pattern of moment release along seismic zones and faults etc. Our current goal is to re-locate all earthquakes with available station arrival data using the following magnitude thresholds: M5.5 for 1964-present, M6.25 for 1918-1963, M7.5 (complemented with significant events in continental regions) for 1900-1917. Phase arrival time data for earthquakes after 1963 are available in digital form from the International Seismological Centre (ISC). For earthquakes in the time period 1918-1963, phase data is obtained by scanning the printed International Seismological Summary (ISS) bulletins and applying optical character recognition routines. For earlier earthquakes we will collect phase data from individual station bulletins. We will illustrate some of the most significant results of this relocation effort, including aftershock distributions for large earthquakes, systematic differences in epicenter and depth with respect to previous location, examples of grossly mislocated events, etc.

  8. Investigating Landslides Caused by Earthquakes A Historical Review

    NASA Astrophysics Data System (ADS)

    Keefer, David K.

    Post-earthquake field investigations of landslide occurrence have provided a basis for understanding, evaluating, and mapping the hazard and risk associated withearthquake-induced landslides. This paper traces thehistorical development of knowledge derived from these investigations. Before 1783, historical accounts of the occurrence of landslides in earthquakes are typically so incomplete and vague that conclusions based on these accounts are of limited usefulness. For example, the number of landslides triggered by a given event is almost always greatly underestimated. The first formal, scientific post-earthquake investigation that included systematic documentation of the landslides was undertaken in the Calabria region of Italy after the 1783 earthquake swarm. From then until the mid-twentieth century, the best information on earthquake-induced landslides came from a succession ofpost-earthquake investigations largely carried out by formal commissions that undertook extensive ground-based field studies. Beginning in the mid-twentieth century, when the use of aerial photography became widespread, comprehensive inventories of landslide occurrence have been made for several earthquakes in the United States, Peru, Guatemala, Italy, El Salvador, Japan, and Taiwan. Techniques have also been developed for performing ``retrospective'' analyses years or decades after an earthquake that attempt to reconstruct the distribution of landslides triggered by the event. The additional use of Geographic Information System (GIS) processing and digital mapping since about 1989 has greatly facilitated the level of analysis that can applied to mapped distributions of landslides. Beginning in 1984, syntheses of worldwide and national data on earthquake-induced landslides have defined their general characteristics and relations between their occurrence and various geologic and seismic parameters. However, the number of comprehensive post-earthquake studies of landslides is still

  9. OMG Earthquake! Can Twitter improve earthquake response?

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    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 its earthquake response products and the delivery of hazard information. The goal is to gather near real-time, earthquake-related messages (tweets) and provide geo-located earthquake detections and rough maps of the corresponding felt areas. Twitter and other social Internet technologies are providing the general public with anecdotal earthquake hazard information before scientific information has been published from authoritative sources. People local to an event often publish information within seconds via these technologies. In contrast, depending on the location of the earthquake, scientific alerts take between 2 to 20 minutes. Examining the tweets following the March 30, 2009, M4.3 Morgan Hill earthquake shows it is possible (in some cases) to rapidly detect and map the felt area of an earthquake using Twitter responses. Within a minute of the earthquake, the frequency of “earthquake” tweets rose above the background level of less than 1 per hour to about 150 per minute. Using the tweets submitted in the first minute, a rough map of the felt area can be obtained by plotting the tweet locations. Mapping the tweets from the first six minutes shows observations extending from Monterey to Sacramento, similar to the perceived shaking region mapped by the USGS “Did You Feel It” system. The tweets submitted after the earthquake also provided (very) short first-impression narratives from people who experienced the shaking. Accurately assessing the potential and robustness of a Twitter-based system is difficult because only tweets spanning the previous seven days can be searched, making a historical study impossible. We have, however, been archiving tweets for several months, and it is clear that significant limitations do exist. The main drawback is the lack of quantitative information

  10. Earthquakes and Schools

    ERIC Educational Resources Information Center

    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.…

  11. Regional spectral analysis of moderate earthquakes in northeastern North America—Final Report to the Nuclear Regulatory Commission, Project V6240, Task 3

    USGS Publications Warehouse

    Boatwright, John

    2018-06-21

    We analyze the Fourier spectra of S+Lg+surface wave groups from the horizontal and vertical components of broadband and accelerogram recordings of 120 small and moderate (2< Mw <6) earthquakes recorded by Canadian and American stations sited on rock at distances from 3 to 600 kilometers. There are seven Mw 4.0–4.5, six Mw 4.5–5.0, and three Mw ≥5 earthquakes in this event set. We test the regional spectral analysis by comparing the moment magnitudes with the moment magnitudes from the earthquake moment tensors determined by Bob Herrmann (St. Louis University) for 27 events, obtaining dMw=0.004±0.074. We determine the Lg attenuation in seven regions within northeastern North America: Charlevoix, lower St. Lawrence, Maine, Northern New York, lower Great Lakes, Ontario, and Nunavut. These attenuation estimates yield an average attenuation Q= (368±13)f (0.54±0.02) for the Appalachian region, a stronger attenuation Q= (317±16)f (0.54±0.03) for the Appalachian lowlands, and a weaker attenuation Q=(455±20)f (0.51±0.02) for Ontario and western Quebec. For events in Nunavut and northernmost Quebec, we estimate a similar attenuation for r <450 km, but a weaker attenuation Q= (773±70)f (0.27±0.06) for Lg propagation for 450< r <1700 kilometers. This far-regional attenuation allows us to analyze recordings of the 1989 Ungava and Payne Bay earthquakes obtained in Ontario and southern Quebec. We use these regional attenuations to determine the corner frequencies, stress drops, and radiated energies of the 120 earthquakes.

  12. Demand surge following earthquakes

    USGS Publications Warehouse

    Olsen, Anna H.

    2012-01-01

    Demand surge is understood to be a socio-economic phenomenon where repair costs for the same damage are higher after large- versus small-scale natural disasters. It has reportedly increased monetary losses by 20 to 50%. In previous work, a model for the increased costs of reconstruction labor and materials was developed for hurricanes in the Southeast United States. The model showed that labor cost increases, rather than the material component, drove the total repair cost increases, and this finding could be extended to earthquakes. A study of past large-scale disasters suggested that there may be additional explanations for demand surge. Two such explanations specific to earthquakes are the exclusion of insurance coverage for earthquake damage and possible concurrent causation of damage from an earthquake followed by fire or tsunami. Additional research into these aspects might provide a better explanation for increased monetary losses after large- vs. small-scale earthquakes.

  13. Turkish Compulsory Earthquake Insurance and "Istanbul Earthquake

    NASA Astrophysics Data System (ADS)

    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

  14. Earthquakes; January-February 1982

    USGS Publications Warehouse

    Person, W.J.

    1982-01-01

    In the United States, a number of earthquakes occurred, but only minor damage was reported. Arkansas experienced a swarm of earthquakes beginning on January 12. Canada experienced one of its strongest earthquakes in a number of years on January 9; this earthquake caused slight damage in Maine. 

  15. Earthquakes; July-August, 1978

    USGS Publications Warehouse

    Person, W.J.

    1979-01-01

    Earthquake activity during this period was about normal. Deaths from earthquakes were reported from Greece and Guatemala. Three major earthquakes (magnitude 7.0-7.9) occurred in Taiwan, Chile, and Costa Rica. In the United States, the most significant earthquake was a magnitude 5.6 on August 13 in southern California. 

  16. Earthquakes, September-October 1986

    USGS Publications Warehouse

    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.

  17. Sun, Moon and Earthquakes

    NASA Astrophysics Data System (ADS)

    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.

  18. Earthquakes and emergence

    NASA Astrophysics Data System (ADS)

    Earthquakes and emerging infections may not have a direct cause and effect relationship like tax evasion and jail, but new evidence suggests that there may be a link between the two human health hazards. Various media accounts have cited a massive 1993 earthquake in Maharashtra as a potential catalyst of the recent outbreak of plague in India that has claimed more than 50 lives and alarmed the world. The hypothesis is that the earthquake may have uprooted underground rat populations that carry the fleas infected with the bacterium that causes bubonic plague and can lead to the pneumonic form of the disease that is spread through the air.

  19. Implications of the Mw9.0 Tohoku-Oki earthquake for ground motion scaling with source, path, and site parameters

    USGS Publications Warehouse

    Stewart, Jonathan P.; Midorikawa, Saburoh; Graves, Robert W.; Khodaverdi, Khatareh; Kishida, Tadahiro; Miura, Hiroyuki; Bozorgnia, Yousef; Campbell, Kenneth W.

    2013-01-01

    The Mw9.0 Tohoku-oki Japan earthquake produced approximately 2,000 ground motion recordings. We consider 1,238 three-component accelerograms corrected with component-specific low-cut filters. The recordings have rupture distances between 44 km and 1,000 km, time-averaged shear wave velocities of VS30 = 90 m/s to 1,900 m/s, and usable response spectral periods of 0.01 sec to >10 sec. The data support the notion that the increase of ground motions with magnitude saturates at large magnitudes. High-frequency ground motions demonstrate faster attenuation with distance in backarc than in forearc regions, which is only captured by one of the four considered ground motion prediction equations for subduction earthquakes. Recordings within 100 km of the fault are used to estimate event terms, which are generally positive (indicating model underprediction) at short periods and zero or negative (overprediction) at long periods. We find site amplification to scale minimally with VS30 at high frequencies, in contrast with other active tectonic regions, but to scale strongly with VS30 at low frequencies.

  20. Earthquake Ground Motion Selection

    DOT National Transportation Integrated Search

    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. Earthquake education in California

    USGS Publications Warehouse

    MacCabe, M. P.

    1980-01-01

    In a survey of community response to the earthquake threat in southern California, Ralph Turner and his colleagues in the Department of Sociology at the University of California, Los Angeles, found that the public very definitely wants to be educated about the kinds of problems and hazards they can expect during and after a damaging earthquake; and they also want to know how they can prepare themselves to minimize their vulnerability. Decisionmakers, too, are recognizing this new wave of public concern. 

  2. Injection-induced earthquakes

    USGS Publications Warehouse

    Ellsworth, William L.

    2013-01-01

    Earthquakes in unusual locations have become an important topic of discussion in both North America and Europe, owing to the concern that industrial activity could cause damaging earthquakes. It has long been understood that earthquakes can be induced by impoundment of reservoirs, surface and underground mining, withdrawal of fluids and gas from the subsurface, and injection of fluids into underground formations. Injection-induced earthquakes have, in particular, become a focus of discussion as the application of hydraulic fracturing to tight shale formations is enabling the production of oil and gas from previously unproductive formations. Earthquakes can be induced as part of the process to stimulate the production from tight shale formations, or by disposal of wastewater associated with stimulation and production. Here, I review recent seismic activity that may be associated with industrial activity, with a focus on the disposal of wastewater by injection in deep wells; assess the scientific understanding of induced earthquakes; and discuss the key scientific challenges to be met for assessing this hazard.

  3. Charles Darwin's earthquake reports

    NASA Astrophysics Data System (ADS)

    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

  4. Detailed source process of the 2007 Tocopilla earthquake.

    NASA Astrophysics Data System (ADS)

    Peyrat, S.; Madariaga, R.; Campos, J.; Asch, G.; Favreau, P.; Bernard, P.; Vilotte, J.

    2008-05-01

    We investigated the detail rupture process of the Tocopilla earthquake (Mw 7.7) of the 14 November 2007 and of the main aftershocks that occurred in the southern part of the North Chile seismic gap using strong motion data. The earthquake happen in the middle of the permanent broad band and strong motion network IPOC newly installed by GFZ and IPGP, and of a digital strong-motion network operated by the University of Chile. The Tocopilla earthquake is the last large thrust subduction earthquake that occurred since the major Iquique 1877 earthquake which produced a destructive tsunami. The Arequipa (2001) and Antofagasta (1995) earthquakes already ruptured the northern and southern parts of the gap, and the intraplate intermediate depth Tarapaca earthquake (2005) may have changed the tectonic loading of this part of the Peru-Chile subduction zone. For large earthquakes, the depth of the seismic rupture is bounded by the depth of the seismogenic zone. What controls the horizontal extent of the rupture for large earthquakes is less clear. Factors that influence the extent of the rupture include fault geometry, variations of material properties and stress heterogeneities inherited from the previous ruptures history. For subduction zones where structures are not well known, what may have stopped the rupture is not obvious. One crucial problem raised by the Tocopilla earthquake is to understand why this earthquake didn't extent further north, and at south, what is the role of the Mejillones peninsula that seems to act as a barrier. The focal mechanism was determined using teleseismic waveforms inversion and with a geodetic analysis (cf. Campos et al.; Bejarpi et al., in the same session). We studied the detailed source process using the strong motion data available. This earthquake ruptured the interplate seismic zone over more than 150 km and generated several large aftershocks, mainly located south of the rupture area. The strong-motion data show clearly two S

  5. Nowcasting Earthquakes and Tsunamis

    NASA Astrophysics Data System (ADS)

    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

  6. Extending earthquakes' reach through cascading.

    PubMed

    Marsan, David; Lengliné, Olivier

    2008-02-22

    Earthquakes, whatever their size, can trigger other earthquakes. Mainshocks cause aftershocks to occur, which in turn activate their own local aftershock sequences, resulting in a cascade of triggering that extends the reach of the initial mainshock. A long-lasting difficulty is to determine which earthquakes are connected, either directly or indirectly. Here we show that this causal structure can be found probabilistically, with no a priori model nor parameterization. Large regional earthquakes are found to have a short direct influence in comparison to the overall aftershock sequence duration. Relative to these large mainshocks, small earthquakes collectively have a greater effect on triggering. Hence, cascade triggering is a key component in earthquake interactions.

  7. Rupture History of the 2001 Nisqually Washington Earthquake

    NASA Astrophysics Data System (ADS)

    Xu, Q.; Creager, K. C.; Crosson, R. S.

    2001-12-01

    We analyze the temporal-spatial rupture history of the magnitude 6.8 February 28, 2001 Nisqually earthquake using about two dozen 3-component strong-motion records from the Pacific Northwest Seismic Network (PNSN) and the USGS National Strong Motion Program (NSMP) network. We employ a finite-fault inversion scheme similar to Hartzell and Heaton [Bull. Seism. Soc. Am., 1983] to recover the slip history. We assume rupture initiates at the epicenter and origin time determined using PNSN P arrival times and a high-resolution 3-D velocity model. Hypocentral depth is 54 km based on our analysis of teleseismic pP-P times and the regional 3-D model. Using the IASP91 standard Earth model to explain the pP-P times gives a depth of 58 km. Three-component strong motion accelerograms are integrated to obtain velocity, low-pass filtered at 4 s period and windowed to include the direct P- and S- wave arrivals. Theoretical Green's functions are calculated using the Direct Solution Method (DSM) [Cummins, etal, Geophys. Res. Lett., 1994] for each of 169, 4km x 4km, subfaults which lie on one of the two fault plates specified by the Harvard CMT solution. A unique 1-D model that gives an adequate representation of velocity structure for each station is obtained by path averaging the 3-D tomographic model. The S velocity model is generated from the P velocity model. For Vp larger than 4.5 km/s, We use the linear relationship Vs=0.18+0.52Vp obtained from laboratory measurements of local mafic rock samples. For slower velocities, probably associated with sedimentary rocks, we derived Vs=Vp/2.04 which best fits the strong-motion S-arrival times. The resulting source model indicates unilateral rupture along a fault that is elongated in the north-south direction. Inversion for the near vertical (strike 1° , dip 72° ) and horizontal (strike 183° , dip 18° ) fault planes reveal the same source directivity, however, the horizontal fault plane gives a slightly better fit to the data than

  8. Earthquake impact scale

    USGS Publications Warehouse

    Wald, D.J.; Jaiswal, K.S.; Marano, K.D.; Bausch, D.

    2011-01-01

    With the advent of the USGS prompt assessment of global earthquakes for response (PAGER) system, which rapidly assesses earthquake impacts, U.S. and international earthquake responders are reconsidering their automatic alert and activation levels and response procedures. To help facilitate rapid and appropriate earthquake response, an Earthquake Impact Scale (EIS) is proposed on the basis of two complementary criteria. On the basis of the estimated cost of damage, one is most suitable for domestic events; the other, on the basis of estimated ranges of fatalities, is generally more appropriate for global events, particularly in developing countries. Simple thresholds, derived from the systematic analysis of past earthquake impact and associated response levels, are quite effective in communicating predicted impact and response needed after an event through alerts of green (little or no impact), yellow (regional impact and response), orange (national-scale impact and response), and red (international response). Corresponding fatality thresholds for yellow, orange, and red alert levels are 1, 100, and 1,000, respectively. For damage impact, yellow, orange, and red thresholds are triggered by estimated losses reaching $1M, $100M, and $1B, respectively. The rationale for a dual approach to earthquake alerting stems from the recognition that relatively high fatalities, injuries, and homelessness predominate in countries in which local building practices typically lend themselves to high collapse and casualty rates, and these impacts lend to prioritization for international response. In contrast, financial and overall societal impacts often trigger the level of response in regions or countries in which prevalent earthquake resistant construction practices greatly reduce building collapse and resulting fatalities. Any newly devised alert, whether economic- or casualty-based, should be intuitive and consistent with established lexicons and procedures. Useful alerts should

  9. Earthquake number forecasts testing

    NASA Astrophysics Data System (ADS)

    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

  10. Rupture, waves and earthquakes.

    PubMed

    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.

  11. Rupture, waves and earthquakes

    PubMed Central

    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. PMID:28077808

  12. LIDAR Investigation Of The 2004 Niigata Ken Chuetsu, Japan, Earthquake

    NASA Astrophysics Data System (ADS)

    Kayen, R.; Pack, R. T.; Sugimoto, S.; Tanaka, H.

    2005-12-01

    The 23 October 2004 Niigata Ken Chuetsu, Japan, Mw 6.6 earthquake was the most significant earthquake to affect Japan since the 1995 Kobe earthquake. Forty people were killed, almost 3,000 injured, and numerous landslides destroyed entire upland villages. Landslides and permanent ground deformation caused extensive damage to roads, rail lines and other lifelines, resulting in major economic disruption. The cities and towns most significantly affected by the earthquake were Nagaoka, Ojiya, and the mountainous rural areas of Yamakoshi village and Kawaguchi town. Our EERI team traveled with a tripod mounted LIDAR (Light Detection and Ranging) unit, a scanning-laser that creates ultra high-resolution 3-D digital terrain models of the earthquake damaged surfaces the ground, structures, and life-lines. This new technology allows for rapid and remote sensing of damaged terrain. Ground-based LIDAR has an accuracy range of 0.5-2.5 cm, and can illuminate targets up to 400m away from the sensor. During a single tripod-mounted LIDAR scan of 10 minutes, several million survey points are collected and processed into an ultra-high resolution terrain model of the damaged ground or structure. There are several benefits in acquiring these LIDAR data in the initial reconnaissance effort after the earthquake. First, we record the detailed failure morphologies of damaged ground and structures in order to make measurements that are either impractical or impossible by conventional survey means. The digital terrain models allow us to enlarge, enhance and rotate data in order to visualize damage in orientations and scales not previously possible. This ability to visualize damage allows us to better understand failure modes. Finally, LIDAR allows us to archive 3-D terrain models so that the engineering community can evaluate analytical and numerical models of deformation potential against detailed field measurements. Here, we discuss the findings of this 2004 Niigata Chuetsu Earthquake (M6

  13. Earthquakes, September-October 1984

    USGS Publications Warehouse

    Person, W.J.

    1985-01-01

    In the United States, Wyoming experienced a couple of moderate earthquakes, and off the coast of northern California, a strong earthquake shook much of the northern coast of California and parts of the Oregon coast. 

  14. Earthquakes, July-August 1991

    USGS Publications Warehouse

    Person, W.J.

    1992-01-01

    There was one major earthquake during this reporting period-a magnitude 7.1 shock off the coast of Northern California on August 17. Earthquake-related deaths were reported from Indonesia, Romania, Peru, and Iraq. 

  15. Topographic changes and their driving factors after 2008 Wenchuan earthquake

    NASA Astrophysics Data System (ADS)

    Li, Congrong; Wang, Ming; Liu, Kai; Xie, Jun

    2018-06-01

    The 2008 Wenchuan Earthquake caused topographic change in the stricken areas because of the occurrence of numerous coseismic landslides. The emergence of new landslides and debris flows and movement of loose materials under the driving force of high rainfall could further shape the local topography. Currently, little attention has been paid to continuously monitoring and assessing topographic changes after the major earthquake. In this research, we obtained an elevation dataset (2002, 2010, 2013 and 2015) based on digital elevation model (DEM) data and a DEM extracted from ZY-3 stereo paired images with validation by field measurement. We quantitatively assessed elevation changes in different years and qualitatively analyzed spatiotemporal variation of the terrain and mass movement across the study area. The results show that the earthquake affected area experienced substantial elevation changes caused by seismic forces and subsequent rainfalls. High rainfall after the earthquake have become the biggest driver of elevation reduction, which overwhelmed elevation increase caused by the major earthquake. Increased post-earthquake erosion intensity has caused large amounts of loose materials to accumulate in river channels, and gullies and on upper-middle mountain slopes, which increases the risk of flooding and geo-hazards in the area.

  16. Principles for selecting earthquake motions in engineering design of large dams

    USGS Publications Warehouse

    Krinitzsky, E.L.; Marcuson, William F.

    1983-01-01

    This report gives a synopsis of the various tools and techniques used in selecting earthquake ground motion parameters for large dams. It presents 18 charts giving newly developed relations for acceleration, velocity, and duration versus site earthquake intensity for near- and far-field hard and soft sites and earthquakes having magnitudes above and below 7. The material for this report is based on procedures developed at the Waterways Experiment Station. Although these procedures are suggested primarily for large dams, they may also be applicable for other facilities. Because no standard procedure exists for selecting earthquake motions in engineering design of large dams, a number of precautions are presented to guide users. The selection of earthquake motions is dependent on which one of two types of engineering analyses are performed. A pseudostatic analysis uses a coefficient usually obtained from an appropriate contour map; whereas, a dynamic analysis uses either accelerograms assigned to a site or specified respunse spectra. Each type of analysis requires significantly different input motions. All selections of design motions must allow for the lack of representative strong motion records, especially near-field motions from earthquakes of magnitude 7 and greater, as well as an enormous spread in the available data. Limited data must be projected and its spread bracketed in order to fill in the gaps and to assure that there will be no surprises. Because each site may have differing special characteristics in its geology, seismic history, attenuation, recurrence, interpreted maximum events, etc., as integrated approach gives best results. Each part of the site investigation requires a number of decisions. In some cases, the decision to use a 'least ork' approach may be suitable, simply assuming the worst of several possibilities and testing for it. Because there are no standard procedures to follow, multiple approaches are useful. For example, peak motions at

  17. Earthquakes; January-February, 1979

    USGS Publications Warehouse

    Person, W.J.

    1979-01-01

    The first major earthquake (magnitude 7.0 to 7.9) of the year struck in southeastern Alaska in a sparsely populated area on February 28. On January 16, Iran experienced the first destructive earthquake of the year causing a number of casualties and considerable damage. Peru was hit by a destructive earthquake on February 16 that left casualties and damage. A number of earthquakes were experienced in parts of the Untied States, but only minor damage was reported. 

  18. Damaging earthquakes: A scientific laboratory

    USGS Publications Warehouse

    Hays, Walter W.; ,

    1996-01-01

    This paper reviews the principal lessons learned from multidisciplinary postearthquake investigations of damaging earthquakes throughout the world during the past 15 years. The unique laboratory provided by a damaging earthquake in culturally different but tectonically similar regions of the world has increased fundamental understanding of earthquake processes, added perishable scientific, technical, and socioeconomic data to the knowledge base, and led to changes in public policies and professional practices for earthquake loss reduction.

  19. Sensing the earthquake

    NASA Astrophysics Data System (ADS)

    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.

  20. Earthquakes, September-October 1978

    USGS Publications Warehouse

    Person, W.J.

    1979-01-01

    The months of September and October were somewhat quiet seismically speaking. One major earthquake, magnitude (M) 7.7 occurred in Iran on September 16. In Germany, a magntidue 5.0 earthquake caused damage and considerable alarm to many people in parts of that country. In the United States, the largest earthquake occurred along the California-Nevada border region. 

  1. Earthquakes, March-April, 1993

    USGS Publications Warehouse

    Person, Waverly J.

    1993-01-01

    Worldwide, only one major earthquake (7.0earthquake, a magnitude 7.2 shock, struck the Santa Cruz Islands region in the South Pacific on March 6. Earthquake-related deaths occurred in the Fiji Islands, China, and Peru.

  2. Earthquakes, September-October 1991

    USGS Publications Warehouse

    Person, W.J.

    1992-01-01

    There were two major earthquakes (7.0-7.9) during this reporting period. the first was in the Solomon Islands on October 14 and the second was in India on October 19. Earthquake-related deaths were reported in Guatemala and India. Htere were no significant earthquakes in the United States during the period covered in this report. 

  3. Earthquakes, September-October 1993

    USGS Publications Warehouse

    Person, W.J.

    1993-01-01

    The fatalities in the United States were caused by two earthquakes in southern Oregon on September 21. These earthquakes, both with magnitude 6.0 and separated in time by about 2 hrs, led to the deaths of two people. One of these deaths was apparently due to a heart attack induced by the earthquake

  4. Earthquakes, March-April 1991

    USGS Publications Warehouse

    Person, W.J.

    1992-01-01

    Two major earthquakes (7.0-7.9) occurred during this reporting period: a magnitude 7.6 in Costa Rica on April 22 and a magntidue 7.0 in the USSR on April 29. Destructive earthquakes hit northern Peru on April 4 and 5. There were no destructive earthquakes in the United States during this period. 

  5. Organizational changes at Earthquakes & Volcanoes

    USGS Publications Warehouse

    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).

  6. Turkish Children's Ideas about Earthquakes

    ERIC Educational Resources Information Center

    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…

  7. Earthquakes, May-June 1991

    USGS Publications Warehouse

    Person, W.J.

    1992-01-01

    In the United States, a magnitude 5.8 earthquake in southern California on June 28 killed two people and caused considerable damage. Strong earthquakes hit Alaska on May 1 and May 30; the May 1 earthquake caused some minor damage. 

  8. [Earthquakes in El Salvador].

    PubMed

    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.

  9. PAGER--Rapid assessment of an earthquake?s impact

    USGS Publications Warehouse

    Wald, D.J.; Jaiswal, K.; Marano, K.D.; Bausch, D.; Hearne, M.

    2010-01-01

    PAGER (Prompt Assessment of Global Earthquakes for Response) is an automated system that produces content concerning the impact of significant earthquakes around the world, informing emergency responders, government and aid agencies, and the media of the scope of the potential disaster. PAGER rapidly assesses earthquake impacts by comparing the population exposed to each level of shaking intensity with models of economic and fatality losses based on past earthquakes in each country or region of the world. Earthquake alerts--which were formerly sent based only on event magnitude and location, or population exposure to shaking--now will also be generated based on the estimated range of fatalities and economic losses.

  10. The mechanism of earthquake

    NASA Astrophysics Data System (ADS)

    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

  11. Earthquakes; March-April 1975

    USGS Publications Warehouse

    Person, W.J.

    1975-01-01

    There were no major earthquakes (magnitude 7.0-7.9) in March or April; however, there were earthquake fatalities in Chile, Iran, and Venezuela and approximately 35 earthquake-related injuries were reported around the world. In the United States a magnitude 6.0 earthquake struck the Idaho-Utah border region. Damage was estimated at about a million dollars. The shock was felt over a wide area and was the largest to hit the continental Untied States since the San Fernando earthquake of February 1971. 

  12. Earthquakes, November-December 1992

    USGS Publications Warehouse

    Person, W.J.

    1993-01-01

    There were two major earthquakes (7.0≤M<8.0) during the last two months of the year, a magntidue 7.5 earthquake on December 12 in the Flores region, Indonesia, and a magnitude 7.0 earthquake on December 20 in the Banda Sea. Earthquakes caused fatalities in China and Indonesia. The greatest number of deaths (2,500) for the year occurred in Indonesia. In Switzerland, six people were killed by an accidental explosion recoreded by seismographs. In teh United States, a magnitude 5.3 earthquake caused slight damage at Big Bear in southern California. 

  13. Multi-source and multi-angle remote sensing image data collection, application and sharing of Beichuan National Earthquake Ruins Museum

    NASA Astrophysics Data System (ADS)

    Lin, Yueguan; Wang, Wei; Wen, Qi; Huang, He; Lin, Jingli; Zhang, Wei

    2015-12-01

    Ms8.0 Wenchuan earthquake that occurred on May 12, 2008 brought huge casualties and property losses to the Chinese people, and Beichuan County was destroyed in the earthquake. In order to leave a site for commemorate of the people, and for science propaganda and research of earthquake science, Beichuan National Earthquake Ruins Museum has been built on the ruins of Beichuan county. Based on the demand for digital preservation of the earthquake ruins park and collection of earthquake damage assessment of research and data needs, we set up a data set of Beichuan National Earthquake Ruins Museum, including satellite remote sensing image, airborne remote sensing image, ground photogrammetry data and ground acquisition data. At the same time, in order to make a better service for earthquake science research, we design the sharing ideas and schemes for this scientific data set.

  14. The 2004 Parkfield, CA Earthquake: A Teachable Moment for Exploring Earthquake Processes, Probability, and Earthquake Prediction

    NASA Astrophysics Data System (ADS)

    Kafka, A.; Barnett, M.; Ebel, J.; Bellegarde, H.; Campbell, L.

    2004-12-01

    The occurrence of the 2004 Parkfield earthquake provided a unique "teachable moment" for students in our science course for teacher education majors. The course uses seismology as a medium for teaching a wide variety of science topics appropriate for future teachers. The 2004 Parkfield earthquake occurred just 15 minutes after our students completed a lab on earthquake processes and earthquake prediction. That lab included a discussion of the Parkfield Earthquake Prediction Experiment as a motivation for the exercises they were working on that day. Furthermore, this earthquake was recorded on an AS1 seismograph right in their lab, just minutes after the students left. About an hour after we recorded the earthquake, the students were able to see their own seismogram of the event in the lecture part of the course, which provided an excellent teachable moment for a lecture/discussion on how the occurrence of the 2004 Parkfield earthquake might affect seismologists' ideas about earthquake prediction. The specific lab exercise that the students were working on just before we recorded this earthquake was a "sliding block" experiment that simulates earthquakes in the classroom. The experimental apparatus includes a flat board on top of which are blocks of wood attached to a bungee cord and a string wrapped around a hand crank. Plate motion is modeled by slowly turning the crank, and earthquakes are modeled as events in which the block slips ("blockquakes"). We scaled the earthquake data and the blockquake data (using how much the string moved as a proxy for time) so that we could compare blockquakes and earthquakes. This provided an opportunity to use interevent-time histograms to teach about earthquake processes, probability, and earthquake prediction, and to compare earthquake sequences with blockquake sequences. We were able to show the students, using data obtained directly from their own lab, how global earthquake data fit a Poisson exponential distribution better

  15. Earthquake Prediction is Coming

    ERIC Educational Resources Information Center

    MOSAIC, 1977

    1977-01-01

    Describes (1) several methods used in earthquake research, including P:S ratio velocity studies, dilatancy models; and (2) techniques for gathering base-line data for prediction using seismographs, tiltmeters, laser beams, magnetic field changes, folklore, animal behavior. The mysterious Palmdale (California) bulge is discussed. (CS)

  16. Earthquake damage to schools

    USGS Publications Warehouse

    McCullough, Heather

    1994-01-01

    These unusual slides show earthquake damage to school and university buildings around the world. They graphically illustrate the potential danger to our schools, and to the welfare of our children, that results from major earthquakes. The slides range from Algeria, where a collapsed school roof is held up only by students' desks; to Anchorage, Alaska, where an elementary school structure has split in half; to California and other areas, where school buildings have sustained damage to walls, roofs, and chimneys. Interestingly, all the United States earthquakes depicted in this set of slides occurred either on a holiday or before or after school hours, except the 1935 tremor in Helena, Montana, which occurred at 11:35 am. It undoubtedly would have caused casualties had the schools not been closed days earlier by Helena city officials because of a damaging foreshock. Students in Algeria, the People's Republic of China, Armenia, and other stricken countries were not so fortunate. This set of slides represents 17 destructive earthquakes that occurred in 9 countries, and covers more than a century--from 1886 to 1988. Two of the tremors, both of which occurred in the United States, were magnitude 8+ on the Richter Scale, and four were magnitude 7-7.9. The events represented by the slides (see table below) claimed more than a quarter of a million lives.

  17. Fractal dynamics of earthquakes

    SciTech Connect

    Bak, P.; Chen, K.

    1995-05-01

    Many objects in nature, from mountain landscapes to electrical breakdown and turbulence, have a self-similar fractal spatial structure. It seems obvious that to understand the origin of self-similar structures, one must understand the nature of the dynamical processes that created them: temporal and spatial properties must necessarily be completely interwoven. This is particularly true for earthquakes, which have a variety of fractal aspects. The distribution of energy released during earthquakes is given by the Gutenberg-Richter power law. The distribution of epicenters appears to be fractal with dimension D {approx} 1--1.3. The number of after shocks decay as a function ofmore » time according to the Omori power law. There have been several attempts to explain the Gutenberg-Richter law by starting from a fractal distribution of faults or stresses. But this is a hen-and-egg approach: to explain the Gutenberg-Richter law, one assumes the existence of another power-law--the fractal distribution. The authors present results of a simple stick slip model of earthquakes, which evolves to a self-organized critical state. Emphasis is on demonstrating that empirical power laws for earthquakes indicate that the Earth`s crust is at the critical state, with no typical time, space, or energy scale. Of course the model is tremendously oversimplified; however in analogy with equilibrium phenomena they do not expect criticality to depend on details of the model (universality).« less

  18. Road Damage Following Earthquake

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Ground shaking triggered liquefaction in a subsurface layer of water-saturated sand, producing differential lateral and vertical movement in a overlying carapace of unliquified sand and slit, which moved from right to left towards the Pajaro River. This mode of ground failure, termed lateral spreading, is a principal cause of liquefaction-related earthquake damage caused by the Oct. 17, 1989, Loma Prieta earthquake. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditons that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. Credit: S.D. Ellen, U.S. Geological Survey

  19. Baja Earthquake Perspective View

    NASA Image and Video Library

    2010-04-05

    The topography surrounding the Laguna Salada Fault in the Mexican state of Baja, California, is shown in this combined radar image and topographic view with data from NASA Shuttle Radar Topography Mission where a 7.2 earthquake struck on April 4, 2010.

  20. Optimum design of bridges with superelastic-friction base isolators against near-field earthquakes

    NASA Astrophysics Data System (ADS)

    Ozbulut, Osman E.; Hurlebaus, Stefan

    2010-04-01

    The seismic response of a multi-span continuous bridge isolated with novel superelastic-friction base isolator (S-FBI) is investigated under near-field earthquakes. The isolation system consists of a flat steel-Teflon sliding bearing and a superelastic NiTi shape memory alloy (SMA) device. Sliding bearings limit the maximum seismic forces transmitted to the superstructure to a certain value that is a function of friction coefficient of sliding interface. Superelastic SMA device provides restoring capability to the isolation system together with additional damping characteristics. The key design parameters of an S-FBI system are the natural period of the isolated, yielding displacement of SMA device, and the friction coefficient of the sliding bearings. The goal of this study is to obtain optimal values for each design parameter by performing sensitivity analyses of the isolated bridge. First, a three-span continuous bridge is modeled as a two-degrees-of-freedom with S-FBI system. A neuro-fuzzy model is used to capture rate-dependent nonlinear behavior of SMA device. A time-dependent method which employs wavelets to adjust accelerograms to match a target response spectrum with minimum changes on the other characteristics of ground motions is used to generate ground motions used in the simulations. Then, a set of nonlinear time history analyses of the isolated bridge is performed. The variation of the peak response quantities of the isolated bridge is shown as a function of design parameters. Also, the influence of temperature variations on the effectiveness of S-FBI system is evaluated. The results show that the optimum design of the isolated bridge with S-FBI system can be achieved by a judicious specification of design parameters.

  1. The EM Earthquake Precursor

    NASA Astrophysics Data System (ADS)

    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

  2. WGCEP Historical California Earthquake Catalog

    USGS Publications Warehouse

    Felzer, Karen R.; Cao, Tianqing

    2008-01-01

    This appendix provides an earthquake catalog for California and the surrounding area. Our goal is to provide a listing for all known M > 5.5 earthquakes that occurred from 1850-1932 and all known M > 4.0 earthquakes that occurred from 1932-2006 within the region of 31.0 to 43.0 degrees North and -126.0 to -114.0 degrees West. Some pre-1932 earthquakes 4 5, before the Northern California network was online. Some earthquakes from 1900-1932, and particularly from 1910-1932 are also based on instrumental readings, but the quality of the instrumental record and the resulting analysis are much less precise than for later listings. A partial exception is for some of the largest earthquakes, such as the San Francisco earthquake of April 18, 1906, for which global teleseismic records (Wald et al. 1993) and geodetic measurements (Thatcher et al. 1906) have been used to help determine magnitudes.

  3. The HayWired Earthquake Scenario—Earthquake Hazards

    USGS Publications Warehouse

    Detweiler, Shane T.; Wein, Anne M.

    2017-04-24

    The HayWired scenario is a hypothetical earthquake sequence that is being used to better understand hazards for the San Francisco Bay region during and after an earthquake of magnitude 7 on the Hayward Fault. The 2014 Working Group on California Earthquake Probabilities calculated that there is a 33-percent likelihood of a large (magnitude 6.7 or greater) earthquake occurring on the Hayward Fault within three decades. A large Hayward Fault earthquake will produce strong ground shaking, permanent displacement of the Earth’s surface, landslides, liquefaction (soils becoming liquid-like during shaking), and subsequent fault slip, known as afterslip, and earthquakes, known as aftershocks. The most recent large earthquake on the Hayward Fault occurred on October 21, 1868, and it ruptured the southern part of the fault. The 1868 magnitude-6.8 earthquake occurred when the San Francisco Bay region had far fewer people, buildings, and infrastructure (roads, communication lines, and utilities) than it does today, yet the strong ground shaking from the earthquake still caused significant building damage and loss of life. The next large Hayward Fault earthquake is anticipated to affect thousands of structures and disrupt the lives of millions of people. Earthquake risk in the San Francisco Bay region has been greatly reduced as a result of previous concerted efforts; for example, tens of billions of dollars of investment in strengthening infrastructure was motivated in large part by the 1989 magnitude 6.9 Loma Prieta earthquake. To build on efforts to reduce earthquake risk in the San Francisco Bay region, the HayWired earthquake scenario comprehensively examines the earthquake hazards to help provide the crucial scientific information that the San Francisco Bay region can use to prepare for the next large earthquake, The HayWired Earthquake Scenario—Earthquake Hazards volume describes the strong ground shaking modeled in the scenario and the hazardous movements of

  4. The 1868 Hayward Earthquake Alliance: A Case Study - Using an Earthquake Anniversary to Promote Earthquake Preparedness

    NASA Astrophysics Data System (ADS)

    Brocher, T. M.; Garcia, S.; Aagaard, B. T.; Boatwright, J. J.; Dawson, T.; Hellweg, M.; Knudsen, K. L.; Perkins, J.; Schwartz, D. P.; Stoffer, P. W.; Zoback, M.

    2008-12-01

    Last October 21st marked the 140th anniversary of the M6.8 1868 Hayward Earthquake, the last damaging earthquake on the southern Hayward Fault. This anniversary was used to help publicize the seismic hazards associated with the fault because: (1) the past five such earthquakes on the Hayward Fault occurred about 140 years apart on average, and (2) the Hayward-Rodgers Creek Fault system is the most likely (with a 31 percent probability) fault in the Bay Area to produce a M6.7 or greater earthquake in the next 30 years. To promote earthquake awareness and preparedness, over 140 public and private agencies and companies and many individual joined the public-private nonprofit 1868 Hayward Earthquake Alliance (1868alliance.org). The Alliance sponsored many activities including a public commemoration at Mission San Jose in Fremont, which survived the 1868 earthquake. This event was followed by an earthquake drill at Bay Area schools involving more than 70,000 students. The anniversary prompted the Silver Sentinel, an earthquake response exercise based on the scenario of an earthquake on the Hayward Fault conducted by Bay Area County Offices of Emergency Services. 60 other public and private agencies also participated in this exercise. The California Seismic Safety Commission and KPIX (CBS affiliate) produced professional videos designed forschool classrooms promoting Drop, Cover, and Hold On. Starting in October 2007, the Alliance and the U.S. Geological Survey held a sequence of press conferences to announce the release of new research on the Hayward Fault as well as new loss estimates for a Hayward Fault earthquake. These included: (1) a ShakeMap for the 1868 Hayward earthquake, (2) a report by the U. S. Bureau of Labor Statistics forecasting the number of employees, employers, and wages predicted to be within areas most strongly shaken by a Hayward Fault earthquake, (3) new estimates of the losses associated with a Hayward Fault earthquake, (4) new ground motion

  5. Historical earthquake research in Austria

    NASA Astrophysics Data System (ADS)

    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.

  6. Earthquakes: Recurrence and Interoccurrence Times

    NASA Astrophysics Data System (ADS)

    Abaimov, S. G.; Turcotte, D. L.; Shcherbakov, R.; Rundle, J. B.; Yakovlev, G.; Goltz, C.; Newman, W. I.

    2008-04-01

    The purpose of this paper is to discuss the statistical distributions of recurrence times of earthquakes. Recurrence times are the time intervals between successive earthquakes at a specified location on a specified fault. Although a number of statistical distributions have been proposed for recurrence times, we argue in favor of the Weibull distribution. The Weibull distribution is the only distribution that has a scale-invariant hazard function. We consider three sets of characteristic earthquakes on the San Andreas fault: (1) The Parkfield earthquakes, (2) the sequence of earthquakes identified by paleoseismic studies at the Wrightwood site, and (3) an example of a sequence of micro-repeating earthquakes at a site near San Juan Bautista. In each case we make a comparison with the applicable Weibull distribution. The number of earthquakes in each of these sequences is too small to make definitive conclusions. To overcome this difficulty we consider a sequence of earthquakes obtained from a one million year “Virtual California” simulation of San Andreas earthquakes. Very good agreement with a Weibull distribution is found. We also obtain recurrence statistics for two other model studies. The first is a modified forest-fire model and the second is a slider-block model. In both cases good agreements with Weibull distributions are obtained. Our conclusion is that the Weibull distribution is the preferred distribution for estimating the risk of future earthquakes on the San Andreas fault and elsewhere.

  7. Turkish Compulsory Earthquake Insurance (TCIP)

    NASA Astrophysics Data System (ADS)

    Erdik, M.; Durukal, E.; Sesetyan, K.

    2009-04-01

    Through a World Bank project a government-sponsored Turkish Catastrophic Insurance Pool (TCIP) is created in 2000 with the essential aim of transferring the government's financial burden of replacing earthquake-damaged housing to international reinsurance and capital markets. Providing coverage to about 2.9 Million homeowners TCIP is the largest insurance program in the country with about 0.5 Billion USD in its own reserves and about 2.3 Billion USD in total claims paying capacity. The total payment for earthquake damage since 2000 (mostly small, 226 earthquakes) amounts to about 13 Million USD. The country-wide penetration rate is about 22%, highest in the Marmara region (30%) and lowest in the south-east Turkey (9%). TCIP is the sole-source provider of earthquake loss coverage up to 90,000 USD per house. The annual premium, categorized on the basis of earthquake zones type of structure, is about US90 for a 100 square meter reinforced concrete building in the most hazardous zone with 2% deductible. The earthquake engineering related shortcomings of the TCIP is exemplified by fact that the average rate of 0.13% (for reinforced concrete buildings) with only 2% deductible is rather low compared to countries with similar earthquake exposure. From an earthquake engineering point of view the risk underwriting (Typification of housing units to be insured, earthquake intensity zonation and the sum insured) of the TCIP needs to be overhauled. Especially for large cities, models can be developed where its expected earthquake performance (and consequently the insurance premium) can be can be assessed on the basis of the location of the unit (microzoned earthquake hazard) and basic structural attributes (earthquake vulnerability relationships). With such an approach, in the future the TCIP can contribute to the control of construction through differentiation of premia on the basis of earthquake vulnerability.

  8. A new way of telling earthquake stories: MOBEE - the MOBile Earthquake Exhibition

    NASA Astrophysics Data System (ADS)

    Tataru, Dragos; Toma-Danila, Dragos; Nastase, Eduard

    2016-04-01

    In the last decades, the demand and acknowledged importance of science outreach, in general and geophysics in particular, has grown, as demonstrated by many international and national projects and other activities performed by research institutes. The National Institute for Earth Physics (NIEP) from Romania is the leading national institution on earthquake monitoring and research, having at the same time a declared focus on informing and educating a wide audience about geosciences and especially seismology. This is more than welcome, since Romania is a very active country from a seismological point of view, but not too reactive when it comes to diminishing the possible effect of a major earthquake. Over the last few decades, the country has experienced several major earthquakes which have claimed thousands of lives and millions in property damage (1940; 1977; 1986 and 1990 Vrancea earthquakes). In this context, during a partnership started in 2014 together with the National Art University and Siveco IT company, a group of researchers from NIEP initiated the MOBile Earthquake Exhibition (MOBEE) project. The main goal was to design a portable museum to bring on the road educational activities focused on seismology, seismic hazard and Earth science. The exhibition is mainly focused on school students of all ages as it explains the main topics of geophysics through a unique combination of posters, digital animations and apps, large markets and exciting hand-on experiments, 3D printed models and posters. This project is singular in Romania and aims to transmit properly reviewed actual information, regarding the definition of earthquakes, the way natural hazards can affect people, buildings and the environment and the measures to be taken for prevent an aftermath. Many of the presented concepts can be used by teachers as a complementary way of demonstrating physics facts and concepts and explaining processes that shape the dynamic Earth features. It also involves

  9. Earthquake likelihood model testing

    USGS Publications Warehouse

    Schorlemmer, D.; Gerstenberger, M.C.; Wiemer, S.; Jackson, D.D.; Rhoades, D.A.

    2007-01-01

    INTRODUCTIONThe Regional Earthquake Likelihood Models (RELM) project aims to produce and evaluate alternate models of earthquake potential (probability per unit volume, magnitude, and time) for California. Based on differing assumptions, these models are produced to test the validity of their assumptions and to explore which models should be incorporated in seismic hazard and risk evaluation. Tests based on physical and geological criteria are useful but we focus on statistical methods using future earthquake catalog data only. We envision two evaluations: a test of consistency with observed data and a comparison of all pairs of models for relative consistency. Both tests are based on the likelihood method, and both are fully prospective (i.e., the models are not adjusted to fit the test data). To be tested, each model must assign a probability to any possible event within a specified region of space, time, and magnitude. For our tests the models must use a common format: earthquake rates in specified “bins” with location, magnitude, time, and focal mechanism limits.Seismology cannot yet deterministically predict individual earthquakes; however, it should seek the best possible models for forecasting earthquake occurrence. This paper describes the statistical rules of an experiment to examine and test earthquake forecasts. The primary purposes of the tests described below are to evaluate physical models for earthquakes, assure that source models used in seismic hazard and risk studies are consistent with earthquake data, and provide quantitative measures by which models can be assigned weights in a consensus model or be judged as suitable for particular regions.In this paper we develop a statistical method for testing earthquake likelihood models. A companion paper (Schorlemmer and Gerstenberger 2007, this issue) discusses the actual implementation of these tests in the framework of the RELM initiative.Statistical testing of hypotheses is a common task and a

  10. Identified EM Earthquake Precursors

    NASA Astrophysics Data System (ADS)

    Jones, Kenneth, II; Saxton, Patrick

    2014-05-01

    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 a number of custom rock experiments, two hypotheses were formed which could answer the EM wave model. The first hypothesis concerned a sufficient and continuous electron movement either by surface or penetrative flow, and the second regarded a novel approach to radio transmission. Electron flow along fracture surfaces was determined to be inadequate in creating strong EM fields, because rock has a very high electrical resistance making it a high quality insulator. Penetrative flow could not be corroborated as well, because it was discovered that rock was absorbing and confining electrons to a very thin skin depth. Radio wave transmission and detection worked with every single test administered. This hypothesis was reviewed for propagating, long-wave generation with sufficient amplitude, and the capability of penetrating solid rock. Additionally, fracture spaces, either air or ion-filled, can facilitate this concept from great depths and allow for surficial detection. A few propagating precursor signals have been detected in the field occurring with associated phases using custom-built loop antennae. Field testing was conducted in Southern California from 2006-2011, and outside the NE Texas town of Timpson in February, 2013. The antennae have mobility and observations were noted for

  11. Geophysical Anomalies and Earthquake Prediction

    NASA Astrophysics Data System (ADS)

    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

  12. The October 17, 1989, Loma Prieta, California, earthquake: selected photographs

    USGS Publications Warehouse

    Nakata, John K.; Meyer, C.E.; Wilshire, H.G.; Tinsley, J. C.; Updegrove, W.S.; Peterson, D.M.; Ellen, S.D.; Haugerud, R.A.; McLaughlin, R.J.; Fisher, G.R.; Diggles, M.F.

    1999-01-01

    This CD-ROM contains 103 digitized color 35-mm images from Open-File Report 90-547 (Nakata and others, 1990). Our photographic coverage reflects the time and resources available immediately after the event and is not intended to portray the full extent of earthquake damage. This CD-ROM provides images for use by the interested public, multimedia producers, desktop publishers, and the high-end printing industry.

  13. Earthquake technology fights crime

    USGS Publications Warehouse

    Lahr, John C.; Ward, Peter L.; Stauffer, Peter H.; Hendley, James W.

    1996-01-01

    Scientists with the U.S. Geological Survey have adapted their methods for quickly finding the exact source of an earthquake to the problem of locating gunshots. On the basis of this work, a private company is now testing an automated gunshot-locating system in a San Francisco Bay area community. This system allows police to rapidly pinpoint and respond to illegal gunfire, helping to reduce crime in our neighborhoods.

  14. Fault lubrication during earthquakes.

    PubMed

    Di Toro, G; Han, R; Hirose, T; De Paola, N; Nielsen, S; Mizoguchi, K; Ferri, F; Cocco, M; Shimamoto, T

    2011-03-24

    The determination of rock friction at seismic slip rates (about 1 m s(-1)) is of paramount importance in earthquake mechanics, as fault friction controls the stress drop, the mechanical work and the frictional heat generated during slip. Given the difficulty in determining friction by seismological methods, elucidating constraints are derived from experimental studies. Here we review a large set of published and unpublished experiments (∼300) performed in rotary shear apparatus at slip rates of 0.1-2.6 m s(-1). The experiments indicate a significant decrease in friction (of up to one order of magnitude), which we term fault lubrication, both for cohesive (silicate-built, quartz-built and carbonate-built) rocks and non-cohesive rocks (clay-rich, anhydrite, gypsum and dolomite gouges) typical of crustal seismogenic sources. The available mechanical work and the associated temperature rise in the slipping zone trigger a number of physicochemical processes (gelification, decarbonation and dehydration reactions, melting and so on) whose products are responsible for fault lubrication. The similarity between (1) experimental and natural fault products and (2) mechanical work measures resulting from these laboratory experiments and seismological estimates suggests that it is reasonable to extrapolate experimental data to conditions typical of earthquake nucleation depths (7-15 km). It seems that faults are lubricated during earthquakes, irrespective of the fault rock composition and of the specific weakening mechanism involved.

  15. Housing Damage Following Earthquake

    NASA Technical Reports Server (NTRS)

    1989-01-01

    An automobile lies crushed under the third story of this apartment building in the Marina District after the Oct. 17, 1989, Loma Prieta earthquake. The ground levels are no longer visible because of structural failure and sinking due to liquefaction. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditons that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. Credit: J.K. Nakata, U.S. Geological Survey.

  16. Earthquake Potential in Myanmar

    NASA Astrophysics Data System (ADS)

    Aung, Hla Hla

    Myanmar region is generally believed to be an area of high earthquake potential from the point of view of seismic activity which has been low compared to the surrounding regions like Indonesia, China, and Pakistan. Geoscientists and seismologists predicted earthquakes to occur in the area north of the Sumatra-Andaman Islands, i.e. the southwest and west part of Myanmar. Myanmar tectonic setting relative to East and SE Asia is rather peculiar and unique with different plate tectonic models but similar to the setting of western part of North America. Myanmar crustal blocks are caught within two lithospheric plates of India and Indochina experiencing oblique subduction with major dextral strike-slip faulting of the Sagaing fault. Seismic tomography and thermal structure of India plate along the Sunda subduction zone vary from south to north. Strong partitioning in central Andaman basin where crustal fragmentation and northward dispersion of Burma plate by back-arc spreading mechanism has been operating since Neogene. Northward motion of Burma plate relative to SE Asia would dock against the major continent further north and might have caused the accumulation of strain which in turn will be released as earthquakes in the future.

  17. Earthquake Source Mechanics

    NASA Astrophysics Data System (ADS)

    The past 2 decades have seen substantial progress in our understanding of the nature of the earthquake faulting process, but increasingly, the subject has become an interdisciplinary one. Thus, although the observation of radiated seismic waves remains the primary tool for studying earthquakes (and has been increasingly focused on extracting the physical processes occurring in the “source”), geological studies have also begun to play a more important role in understanding the faulting process. Additionally, defining the physical underpinning for these phenomena has come to be an important subject in experimental and theoretical rock mechanics.In recognition of this, a Maurice Ewing Symposium was held at Arden House, Harriman, N.Y. (the former home of the great American statesman Averill Harriman), May 20-23, 1985. The purpose of the meeting was to bring together the international community of experimentalists, theoreticians, and observationalists who are engaged in the study of various aspects of earthquake source mechanics. The conference was attended by more than 60 scientists from nine countries (France, Italy, Japan, Poland, China, the United Kingdom, United States, Soviet Union, and the Federal Republic of Germany).

  18. Sand Volcano Following Earthquake

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Sand boil or sand volcano measuring 2 m (6.6 ft.) in length erupted in median of Interstate Highway 80 west of the Bay Bridge toll plaza when ground shaking transformed loose water-saturated deposit of subsurface sand into a sand-water slurry (liquefaction) in the October 17, 1989, Loma Prieta earthquake. Vented sand contains marine-shell fragments. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditions that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. (Credit: J.C. Tinsley, U.S. Geological Survey)

  19. Do Earthquakes Shake Stock Markets?

    PubMed Central

    2015-01-01

    This paper examines how major earthquakes affected the returns and volatility of aggregate stock market indices in thirty-five financial markets over the last twenty years. Results show that global financial markets are resilient to shocks caused by earthquakes even if these are domestic. Our analysis reveals that, in a few instances, some macroeconomic variables and earthquake characteristics (gross domestic product per capita, trade openness, bilateral trade flows, earthquake magnitude, a tsunami indicator, distance to the epicenter, and number of fatalities) mediate the impact of earthquakes on stock market returns, resulting in a zero net effect. However, the influence of these variables is market-specific, indicating no systematic pattern across global capital markets. Results also demonstrate that stock market volatility is unaffected by earthquakes, except for Japan. PMID:26197482

  20. Do Earthquakes Shake Stock Markets?

    PubMed

    Ferreira, Susana; Karali, Berna

    2015-01-01

    This paper examines how major earthquakes affected the returns and volatility of aggregate stock market indices in thirty-five financial markets over the last twenty years. Results show that global financial markets are resilient to shocks caused by earthquakes even if these are domestic. Our analysis reveals that, in a few instances, some macroeconomic variables and earthquake characteristics (gross domestic product per capita, trade openness, bilateral trade flows, earthquake magnitude, a tsunami indicator, distance to the epicenter, and number of fatalities) mediate the impact of earthquakes on stock market returns, resulting in a zero net effect. However, the influence of these variables is market-specific, indicating no systematic pattern across global capital markets. Results also demonstrate that stock market volatility is unaffected by earthquakes, except for Japan.

  1. An interactive program on digitizing historical seismograms

    NASA Astrophysics Data System (ADS)

    Xu, Yihe; Xu, Tao

    2014-02-01

    Retrieving information from analog seismograms is of great importance since they are considered as the unique sources that provide quantitative information of historical earthquakes. We present an algorithm for automatic digitization of the seismograms as an inversion problem that forms an interactive program using Matlab® GUI. The program integrates automatic digitization with manual digitization and users can easily switch between the two modalities and carry out different combinations for the optimal results. Several examples about applying the interactive program are given to illustrate the merits of the method.

  2. Persistency of rupture directivity in moderate-magnitude earthquakes in Italy: Implications for seismic hazard

    NASA Astrophysics Data System (ADS)

    Rovelli, A.; Calderoni, G.

    2012-12-01

    A simple method based on the EGF deconvolution in the frequency domain is applied to detect the occurrence of unilateral ruptures in recent damaging earthquakes in Italy. The spectral ratio between event pairs with different magnitudes at individual stations shows large azimuthal variations above corner frequency when the target event is affected by source directivity and the EGF is not or vice versa. The analysis is applied to seismograms and accelerograms recorded during the seismic sequence following the 20 May 2012, Mw 5.6 main shock in Emilia, northern Italy, the 6 April 2009, Mw 6.1 earthquake of L'Aquila, central Italy, and the 26 September 1997, Mw 5.7 and 6.0 shocks in Umbria-Marche, central Italy. Events of each seismic sequence are selected as having consistent focal mechanisms, and the station selection obeys to the constraint of a similar source-to-receiver path for the event pairs. The analyzed data set of L'Aquila consists of 962 broad-band seismograms relative to 69 normal-faulting earthquakes (3.3 ≤ MW ≤ 6.1, according to Herrmann et al., 2011), stations are selected in the distance range 100 to 250 km to minimize differences in propagation paths. The seismogram analysis reveals that a strong along-strike (toward SE) source directivity characterized all of the three Mw > 5.0 shocks. Source directivity was also persistent up to the smallest magnitudes: 65% of earthquakes under study showed evidence of directivity toward SE whereas only one (Mw 3.7) event showed directivity in the opposite direction. Also the Mw 5.6 main shock of the 20 May 2012 in Emilia result in large azimuthal spectral variations indicating unilateral rupture propagation toward SE. According to the reconstructed geometry of the trust-fault plane, the inferred directivity direction suggests top-down rupture propagation. The analysis over the Emilia aftershock sequence is in progress. The third seismic sequence, dated 1997-1998, occurred in the northern Apennines and, similarly

  3. Earthquakes, September-October 1980

    USGS Publications Warehouse

    Person, W.J.

    1981-01-01

    There were two major (magnitudes 7.0-7.9) earthquakes during this reporting period; a magnitude (M) 7.3 in Algeria where many people were killed or injured and extensive damage occurred, and an M=7.2 in the Loyalty Islands region of the South Pacific. Japan was struck by a damaging earthquake on September 24, killing two people and causing injuries. There were no damaging earthquakes in the United States. 

  4. Earthquakes, November-December 1991

    USGS Publications Warehouse

    Person, W.J.

    1992-01-01

    There were three major earthquakes (7.0-7.9) during the last two months of the year: a magntidue 7.0 on November 19 in Columbia, a magnitude 7.4 in the Kuril Islands on December 22, and a magnitude 7.1 in the South Sandwich Islands on December 27. Earthquake-related deaths were reported in Colombia, Yemen, and Iran. there were no significant earthquakes in the United States during this reporting period. 

  5. Earthquakes, May-June 1981

    USGS Publications Warehouse

    Person, W.J.

    1981-01-01

    The months of May and June were somewhat quiet, seismically speaking. There was one major earthquake (7.0-7.9) off the west coast of South Island, New Zealand. The most destructive earthquake during this reporting period was in southern Iran on June 11 which caused fatalities and extensive damage. Peru also experienced a destructive earthquake on June 22 which caused fatalities and damage. In the United States, a number of earthquakes were experienced, but none caused significant damage. 

  6. Earthquakes, July-August 1992

    USGS Publications Warehouse

    Person, W.J.

    1992-01-01

    There were two major earthquakes (7.0≤M<8.0) during this reporting period. A magnitude 7.5 earthquake occurred in Kyrgyzstan on August 19 and a magnitude 7.0 quake struck the Ascension Island region on August 28. In southern California, aftershocks of the magnitude 7.6 earthquake on June 28, 1992, continued. One of these aftershocks caused damage and injuries, and at least one other aftershock caused additional damage. Earthquake-related fatalities were reportred in Kyrgzstan and Pakistan. 

  7. Earthquake Forecasting System in Italy

    NASA Astrophysics Data System (ADS)

    Falcone, G.; Marzocchi, W.; Murru, M.; Taroni, M.; Faenza, L.

    2017-12-01

    In Italy, after the 2009 L'Aquila earthquake, a procedure was developed for gathering and disseminating authoritative information about the time dependence of seismic hazard to help communities prepare for a potentially destructive earthquake. The most striking time dependency of the earthquake occurrence process is the time clustering, which is particularly pronounced in time windows of days and weeks. The Operational Earthquake Forecasting (OEF) system that is developed at the Seismic Hazard Center (Centro di Pericolosità Sismica, CPS) of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) is the authoritative source of seismic hazard information for Italian Civil Protection. The philosophy of the system rests on a few basic concepts: transparency, reproducibility, and testability. In particular, the transparent, reproducible, and testable earthquake forecasting system developed at CPS is based on ensemble modeling and on a rigorous testing phase. Such phase is carried out according to the guidance proposed by the Collaboratory for the Study of Earthquake Predictability (CSEP, international infrastructure aimed at evaluating quantitatively earthquake prediction and forecast models through purely prospective and reproducible experiments). In the OEF system, the two most popular short-term models were used: the Epidemic-Type Aftershock Sequences (ETAS) and the Short-Term Earthquake Probabilities (STEP). Here, we report the results from OEF's 24hour earthquake forecasting during the main phases of the 2016-2017 sequence occurred in Central Apennines (Italy).

  8. ViscoSim Earthquake Simulator

    USGS Publications Warehouse

    Pollitz, Fred

    2012-01-01

    Synthetic seismicity simulations have been explored by the Southern California Earthquake Center (SCEC) Earthquake Simulators Group in order to guide long‐term forecasting efforts related to the Unified California Earthquake Rupture Forecast (Tullis et al., 2012a). In this study I describe the viscoelastic earthquake simulator (ViscoSim) of Pollitz, 2009. Recapitulating to a large extent material previously presented by Pollitz (2009, 2011) I describe its implementation of synthetic ruptures and how it differs from other simulators being used by the group.

  9. Earthquakes in the United States

    USGS Publications Warehouse

    Stover, C.

    1977-01-01

    To supplement data in the report Preliminary Determination of Epicenters (PDE), the National earthquake Information Service (NEIS) also publishes a quarterly circular, Earthquakes in the United States. This provides information on the felt area of U.S earthquakes and their intensity. The main purpose is to describe the larger effects of these earthquakes so that they can be used in seismic risk studies, site evaluations for nuclear power plants, and answering inquiries by the general public.

  10. Digital Citizenship

    ERIC Educational Resources Information Center

    Isman, Aytekin; Canan Gungoren, Ozlem

    2014-01-01

    Era in which we live is known and referred as digital age.In this age technology is rapidly changed and developed. In light of these technological advances in 21st century, schools have the responsibility of training "digital citizen" as well as a good citizen. Digital citizens must have extensive skills, knowledge, Internet and …

  11. Foreshocks, aftershocks, and earthquake probabilities: Accounting for the landers earthquake

    USGS Publications Warehouse

    Jones, Lucile M.

    1994-01-01

    The equation to determine the probability that an earthquake occurring near a major fault will be a foreshock to a mainshock on that fault is modified to include the case of aftershocks to a previous earthquake occurring near the fault. The addition of aftershocks to the background seismicity makes its less probable that an earthquake will be a foreshock, because nonforeshocks have become more common. As the aftershocks decay with time, the probability that an earthquake will be a foreshock increases. However, fault interactions between the first mainshock and the major fault can increase the long-term probability of a characteristic earthquake on that fault, which will, in turn, increase the probability that an event is a foreshock, compensating for the decrease caused by the aftershocks.

  12. Bibliographical search for reliable seismic moments of large earthquakes during 1900-1979 to compute MW in the ISC-GEM Global Instrumental Reference Earthquake Catalogue

    NASA Astrophysics Data System (ADS)

    Lee, William H. K.; Engdahl, E. Robert

    2015-02-01

    Moment magnitude (MW) determinations from the online GCMT Catalogue of seismic moment tensor solutions (GCMT Catalog, 2011) have provided the bulk of MW values in the ISC-GEM Global Instrumental Reference Earthquake Catalogue (1900-2009) for almost all moderate-to-large earthquakes occurring after 1975. This paper describes an effort to determine MW of large earthquakes that occurred prior to the start of the digital seismograph era, based on credible assessments of thousands of seismic moment (M0) values published in the scientific literature by hundreds of individual authors. MW computed from the published M0 values (for a time period more than twice that of the digital era) are preferable to proxy MW values, especially for earthquakes with MW greater than about 8.5, for which MS is known to be underestimated or "saturated". After examining 1,123 papers, we compile a database of seismic moments and related information for 1,003 earthquakes with published M0 values, of which 967 were included in the ISC-GEM Catalogue. The remaining 36 earthquakes were not included in the Catalogue due to difficulties in their relocation because of inadequate arrival time information. However, 5 of these earthquakes with bibliographic M0 (and thus MW) are included in the Catalogue's Appendix. A search for reliable seismic moments was not successful for earthquakes prior to 1904. For each of the 967 earthquakes a "preferred" seismic moment value (if there is more than one) was selected and its uncertainty was estimated according to the data and method used. We used the IASPEI formula (IASPEI, 2005) to compute direct moment magnitudes (MW[M0]) based on the seismic moments (M0), and assigned their errors based on the uncertainties of M0. From 1900 to 1979, there are 129 great or near great earthquakes (MW ⩾ 7.75) - the bibliographic search provided direct MW values for 86 of these events (or 67%), the GCMT Catalog provided direct MW values for 8 events (or 6%), and the remaining 35

  13. Digital Natives or Digital Tribes?

    ERIC Educational Resources Information Center

    Watson, Ian Robert

    2013-01-01

    This research builds upon the discourse surrounding digital natives. A literature review into the digital native phenomena was undertaken and found that researchers are beginning to identify the digital native as not one cohesive group but of individuals influenced by other factors. Primary research by means of questionnaire survey of technologies…

  14. Earthquake Information System

    NASA Technical Reports Server (NTRS)

    1991-01-01

    IAEMIS (Integrated Automated Emergency Management Information System) is the principal tool of an earthquake preparedness program developed by Martin Marietta and the Mid-America Remote Sensing Center (MARC). It is a two-component set of software, data and procedures to provide information enabling management personnel to make informed decisions in disaster situations. The NASA-developed program ELAS, originally used to analyze Landsat data, provides MARC with a spatially-oriented information management system. Additional MARC projects include land resources management, and development of socioeconomic data.

  15. Earthquake Scaling Relations

    NASA Astrophysics Data System (ADS)

    Jordan, T. H.; Boettcher, M.; Richardson, E.

    2002-12-01

    Using scaling relations to understand nonlinear geosystems has been an enduring theme of Don Turcotte's research. In particular, his studies of scaling in active fault systems have led to a series of insights about the underlying physics of earthquakes. This presentation will review some recent progress in developing scaling relations for several key aspects of earthquake behavior, including the inner and outer scales of dynamic fault rupture and the energetics of the rupture process. The proximate observations of mining-induced, friction-controlled events obtained from in-mine seismic networks have revealed a lower seismicity cutoff at a seismic moment Mmin near 109 Nm and a corresponding upper frequency cutoff near 200 Hz, which we interpret in terms of a critical slip distance for frictional drop of about 10-4 m. Above this cutoff, the apparent stress scales as M1/6 up to magnitudes of 4-5, consistent with other near-source studies in this magnitude range (see special session S07, this meeting). Such a relationship suggests a damage model in which apparent fracture energy scales with the stress intensity factor at the crack tip. Under the assumption of constant stress drop, this model implies an increase in rupture velocity with seismic moment, which successfully predicts the observed variation in corner frequency and maximum particle velocity. Global observations of oceanic transform faults (OTFs) allow us to investigate a situation where the outer scale of earthquake size may be controlled by dynamics (as opposed to geologic heterogeneity). The seismicity data imply that the effective area for OTF moment release, AE, depends on the thermal state of the fault but is otherwise independent of fault's average slip rate; i.e., AE ~ AT, where AT is the area above a reference isotherm. The data are consistent with β = 1/2 below an upper cutoff moment Mmax that increases with AT and yield the interesting scaling relation Amax ~ AT1/2. Taken together, the OTF

  16. Earthquakes March-April 1992

    USGS Publications Warehouse

    Person, Waverly J.

    1992-01-01

    The months of March and April were quite active seismically speaking. There was one major earthquake (7.0Earthquake-related deaths were reported in Iran, Costa Rica, Turkey, and Germany.

  17. Earthquakes on Your Dinner Table

    NASA Astrophysics Data System (ADS)

    Alexeev, N. A.; Tape, C.; Alexeev, V. A.

    2016-12-01

    Earthquakes have interesting physics applicable to other phenomena like propagation of waves, also, they affect human lives. This study focused on three questions, how: depth, distance from epicenter and ground hardness affect earthquake strength. Experimental setup consisted of a gelatin slab to simulate crust. The slab was hit with a weight and earthquake amplitude was measured. It was found that earthquake amplitude was larger when the epicenter was deeper, which contradicts observations and probably was an artifact of the design. Earthquake strength was inversely proportional to the distance from the epicenter, which generally follows reality. Soft and medium jello were implanted into hard jello. It was found that earthquakes are stronger in softer jello, which was a result of resonant amplification in soft ground. Similar results are found in Minto Flats, where earthquakes are stronger and last longer than in the nearby hills. Earthquakes waveforms from Minto Flats showed that that the oscillations there have longer periods compared to the nearby hills with harder soil. Two gelatin pieces with identical shapes and different hardness were vibrated on a platform at varying frequencies in order to demonstrate that their resonant frequencies are statistically different. This phenomenon also occurs in Yukon Flats.

  18. Make an Earthquake: Ground Shaking!

    ERIC Educational Resources Information Center

    Savasci, Funda

    2011-01-01

    The main purposes of this activity are to help students explore possible factors affecting the extent of the damage of earthquakes and learn the ways to reduce earthquake damages. In these inquiry-based activities, students have opportunities to develop science process skills and to build an understanding of the relationship among science,…

  19. Earthquakes; July-August 1982

    USGS Publications Warehouse

    Person, W.J.

    1983-01-01

    During this reporting period, there were three major (7.0-7.9) earthquakes all in unpopulated areas. The quakes occurred north of Macquarie Island on July 7, in the Santa Cruz Islands on August 5, and south of Panama on August 19. In the United Stats, a number of earthquakes occurred, but no damage was reported. 

  20. Earthquakes, July-August, 1979

    USGS Publications Warehouse

    Person, W.J.

    1980-01-01

    In the United States, on August 6, central California experienced a moderately strong earthquake, which injured several people and caused some damage. A number of earthquakes occurred in other parts of the United States but caused very little damage. 

  1. Earthquakes Threaten Many American Schools

    ERIC Educational Resources Information Center

    Bailey, Nancy E.

    2010-01-01

    Millions of U.S. children attend schools that are not safe from earthquakes, even though they are in earthquake-prone zones. Several cities and states have worked to identify and repair unsafe buildings, but many others have done little or nothing to fix the problem. The reasons for ignoring the problem include political and financial ones, but…

  2. Earthquake Catalogue of the Caucasus

    NASA Astrophysics Data System (ADS)

    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

  3. Earthquake Early Warning and Public Policy: Opportunities and Challenges

    NASA Astrophysics Data System (ADS)

    Goltz, J. D.; Bourque, L.; Tierney, K.; Riopelle, D.; Shoaf, K.; Seligson, H.; Flores, P.

    2003-12-01

    Development of an earthquake early warning capability and pilot project were objectives of TriNet, a 5-year (1997-2001) FEMA-funded project to develop a state-of-the-art digital seismic network in southern California. In parallel with research to assemble a protocol for rapid analysis of earthquake data and transmission of a signal by TriNet scientists and engineers, the public policy, communication and educational issues inherent in implementation of an earthquake early warning system were addressed by TriNet's outreach component. These studies included: 1) a survey that identified potential users of an earthquake early warning system and how an earthquake early warning might be used in responding to an event, 2) a review of warning systems and communication issues associated with other natural hazards and how lessons learned might be applied to an alerting system for earthquakes, 3) an analysis of organization, management and public policy issues that must be addressed if a broad-based warning system is to be developed and 4) a plan to provide earthquake early warnings to a small number of organizations in southern California as an experimental prototype. These studies provided needed insights into the social and cultural environment in which this new technology will be introduced, an environment with opportunities to enhance our response capabilities but also an environment with significant barriers to overcome to achieve a system that can be sustained and supported. In this presentation we will address the main public policy issues that were subjects of analysis in these studies. They include a discussion of the possible division of functions among organizations likely to be the principle partners in the management of an earthquake early warning system. Drawing on lessons learned from warning systems for other hazards, we will review the potential impacts of false alarms and missed events on warning system credibility, the acceptability of fully automated

  4. Earthquake early warning for Romania - most recent improvements

    NASA Astrophysics Data System (ADS)

    Marmureanu, Alexandru; Elia, Luca; Martino, Claudio; Colombelli, Simona; Zollo, Aldo; Cioflan, Carmen; Toader, Victorin; Marmureanu, Gheorghe; Marius Craiu, George; Ionescu, Constantin

    2014-05-01

    EWS for Vrancea earthquakes uses the time interval (28-32 sec.) between the moment when the earthquake is detected by the local seismic network installed in the epicenter area (Vrancea) and the arrival time of the seismic waves in the protected area (Bucharest) to send earthquake warning to users. In the last years, National Institute for Earth Physics (NIEP) upgraded its seismic network in order to cover better the seismic zones of Romania. Currently the National Institute for Earth Physics (NIEP) operates a real-time seismic network designed to monitor the seismic activity on the Romania territory, dominated by the Vrancea intermediate-depth (60-200 km) earthquakes. The NIEP real-time network consists of 102 stations and two seismic arrays equipped with different high quality digitizers (Kinemetrics K2, Quanterra Q330, Quanterra Q330HR, PS6-26, Basalt), broadband and short period seismometers (CMG3ESP, CMG40T, KS2000, KS54000, KS2000, CMG3T,STS2, SH-1, S13, Ranger, gs21, Mark l22) and acceleration sensors (Episensor). Recent improvement of the seismic network and real-time communication technologies allows implementation of a nation-wide EEWS for Vrancea and other seismic sources from Romania. We present a regional approach to Earthquake Early Warning for Romania earthquakes. The regional approach is based on PRESTo (Probabilistic and Evolutionary early warning SysTem) software platform: PRESTo processes in real-time three channel acceleration data streams: once the P-waves arrival have been detected, it provides earthquake location and magnitude estimations, and peak ground motion predictions at target sites. PRESTo is currently implemented in real- time at National Institute for Earth Physics, Bucharest for several months in parallel with a secondary EEWS. The alert notification is issued only when both systems validate each other. Here we present the results obtained using offline earthquakes originating from Vrancea area together with several real

  5. Intermediate-term earthquake prediction

    USGS Publications Warehouse

    Knopoff, L.

    1990-01-01

    The problems in predicting earthquakes have been attacked by phenomenological methods from pre-historic times to the present. The associations of presumed precursors with large earthquakes often have been remarked upon. the difficulty in identifying whether such correlations are due to some chance coincidence or are real precursors is that usually one notes the associations only in the relatively short time intervals before the large events. Only rarely, if ever, is notice taken of whether the presumed precursor is to be found in the rather long intervals that follow large earthquakes, or in fact is absent in these post-earthquake intervals. If there are enough examples, the presumed correlation fails as a precursor in the former case, while in the latter case the precursor would be verified. Unfortunately, the observer is usually not concerned with the 'uniteresting' intervals that have no large earthquakes

  6. Testing earthquake source inversion methodologies

    USGS Publications Warehouse

    Page, M.; Mai, P.M.; Schorlemmer, D.

    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.

  7. Earthquake hazards: a national threat

    USGS Publications Warehouse

    ,

    2006-01-01

    Earthquakes are one of the most costly natural hazards faced by the Nation, posing a significant risk to 75 million Americans in 39 States. The risks that earthquakes pose to society, including death, injury, and economic loss, can be greatly reduced by (1) better planning, construction, and mitigation practices before earthquakes happen, and (2) providing critical and timely information to improve response after they occur. As part of the multi-agency National Earthquake Hazards Reduction Program, the U.S. Geological Survey (USGS) has the lead Federal responsibility to provide notification of earthquakes in order to enhance public safety and to reduce losses through effective forecasts based on the best possible scientific information.

  8. Early Earthquakes of the Americas

    NASA Astrophysics Data System (ADS)

    Ni, James

    2004-11-01

    Robert Kovach's second book looks at the interplay of earthquake and volcanic events, archeology, and history in the Americas. Throughout history, major earthquakes have caused the deaths of millions of people and have damaged countless cities. Earthquakes undoubtedly damaged prehistoric cities in the Americas, and evidence of these events could be preserved in archeological records. Kovach asks, Did indigenous native cultures-Indians of the Pacific Northwest, Aztecs, Mayas, and Incas-document their natural history? Some events have been explicitly documented, for example, in Mayan codices, but many may have been recorded as myth and legend. Kovach's discussions of how early cultures dealt with fearful events such as earthquakes and volcanic eruptions are colorful, informative, and entertaining, and include, for example, a depiction of how the Maya would talk to maize plants in their fields during earthquakes to reassure them.

  9. Testing an earthquake prediction algorithm

    USGS Publications Warehouse

    Kossobokov, V.G.; Healy, J.H.; Dewey, J.W.

    1997-01-01

    A test to evaluate earthquake prediction algorithms is being applied to a Russian algorithm known as M8. The M8 algorithm makes intermediate term predictions for earthquakes to occur in a large circle, based on integral counts of transient seismicity in the circle. In a retroactive prediction for the period January 1, 1985 to July 1, 1991 the algorithm as configured for the forward test would have predicted eight of ten strong earthquakes in the test area. A null hypothesis, based on random assignment of predictions, predicts eight earthquakes in 2.87% of the trials. The forward test began July 1, 1991 and will run through December 31, 1997. As of July 1, 1995, the algorithm had forward predicted five out of nine earthquakes in the test area, which success ratio would have been achieved in 53% of random trials with the null hypothesis.

  10. Earthquake Simulator Finds Tremor Triggers

    ScienceCinema

    Johnson, Paul

    2018-01-16

    Using a novel device that simulates earthquakes in a laboratory setting, a Los Alamos researcher has found that seismic waves-the sounds radiated from earthquakes-can induce earthquake aftershocks, often long after a quake has subsided. The research provides insight into how earthquakes may be triggered and how they recur. Los Alamos researcher Paul Johnson and colleague Chris Marone at Penn State have discovered how wave energy can be stored in certain types of granular materials-like the type found along certain fault lines across the globe-and how this stored energy can suddenly be released as an earthquake when hit by relatively small seismic waves far beyond the traditional “aftershock zone” of a main quake. Perhaps most surprising, researchers have found that the release of energy can occur minutes, hours, or even days after the sound waves pass; the cause of the delay remains a tantalizing mystery.

  11. A Revised Earthquake Catalogue for South Iceland

    NASA Astrophysics Data System (ADS)

    Panzera, Francesco; Zechar, J. Douglas; Vogfjörd, Kristín S.; Eberhard, David A. J.

    2016-01-01

    In 1991, a new seismic monitoring network named SIL was started in Iceland with a digital seismic system and automatic operation. The system is equipped with software that reports the automatic location and magnitude of earthquakes, usually within 1-2 min of their occurrence. Normally, automatic locations are manually checked and re-estimated with corrected phase picks, but locations are subject to random errors and systematic biases. In this article, we consider the quality of the catalogue and produce a revised catalogue for South Iceland, the area with the highest seismic risk in Iceland. We explore the effects of filtering events using some common recommendations based on network geometry and station spacing and, as an alternative, filtering based on a multivariate analysis that identifies outliers in the hypocentre error distribution. We identify and remove quarry blasts, and we re-estimate the magnitude of many events. This revised catalogue which we consider to be filtered, cleaned, and corrected should be valuable for building future seismicity models and for assessing seismic hazard and risk. We present a comparative seismicity analysis using the original and revised catalogues: we report characteristics of South Iceland seismicity in terms of b value and magnitude of completeness. Our work demonstrates the importance of carefully checking an earthquake catalogue before proceeding with seismicity analysis.

  12. The CATDAT damaging earthquakes database

    NASA Astrophysics Data System (ADS)

    Daniell, J. E.; Khazai, B.; Wenzel, F.; Vervaeck, A.

    2011-08-01

    The global CATDAT damaging earthquakes and secondary effects (tsunami, fire, landslides, liquefaction and fault rupture) database was developed to validate, remove discrepancies, and expand greatly upon existing global databases; and to better understand the trends in vulnerability, exposure, and possible future impacts of such historic earthquakes. Lack of consistency and errors in other earthquake loss databases frequently cited and used in analyses was a major shortcoming in the view of the authors which needed to be improved upon. Over 17 000 sources of information have been utilised, primarily in the last few years, to present data from over 12 200 damaging earthquakes historically, with over 7000 earthquakes since 1900 examined and validated before insertion into the database. Each validated earthquake includes seismological information, building damage, ranges of social losses to account for varying sources (deaths, injuries, homeless, and affected), and economic losses (direct, indirect, aid, and insured). Globally, a slightly increasing trend in economic damage due to earthquakes is not consistent with the greatly increasing exposure. The 1923 Great Kanto (214 billion USD damage; 2011 HNDECI-adjusted dollars) compared to the 2011 Tohoku (>300 billion USD at time of writing), 2008 Sichuan and 1995 Kobe earthquakes show the increasing concern for economic loss in urban areas as the trend should be expected to increase. Many economic and social loss values not reported in existing databases have been collected. Historical GDP (Gross Domestic Product), exchange rate, wage information, population, HDI (Human Development Index), and insurance information have been collected globally to form comparisons. This catalogue is the largest known cross-checked global historic damaging earthquake database and should have far-reaching consequences for earthquake loss estimation, socio-economic analysis, and the global reinsurance field.

  13. Ground Motion Characteristics of Induced Earthquakes in Central North America

    NASA Astrophysics Data System (ADS)

    Atkinson, G. M.; Assatourians, K.; Novakovic, M.

    2017-12-01

    The ground motion characteristics of induced earthquakes in central North America are investigated based on empirical analysis of a compiled database of 4,000,000 digital ground-motion records from events in induced-seismicity regions (especially Oklahoma). Ground-motion amplitudes are characterized non-parametrically by computing median amplitudes and their variability in magnitude-distance bins. We also use inversion techniques to solve for regional source, attenuation and site response effects. Ground motion models are used to interpret the observations and compare the source and attenuation attributes of induced earthquakes to those of their natural counterparts. Significant conclusions are that the stress parameter that controls the strength of high-frequency radiation is similar for induced earthquakes (depth of h 5 km) and shallow (h 5 km) natural earthquakes. By contrast, deeper natural earthquakes (h 10 km) have stronger high-frequency ground motions. At distances close to the epicenter, a greater focal depth (which increases distance from the hypocenter) counterbalances the effects of a larger stress parameter, resulting in motions of similar strength close to the epicenter, regardless of event depth. The felt effects of induced versus natural earthquakes are also investigated using USGS "Did You Feel It?" reports; 400,000 reports from natural events and 100,000 reports from induced events are considered. The felt reports confirm the trends that we expect based on ground-motion modeling, considering the offsetting effects of the stress parameter versus focal depth in controlling the strength of motions near the epicenter. Specifically, felt intensity for a given magnitude is similar near the epicenter, on average, for all event types and depths. At distances more than 10 km from the epicenter, deeper events are felt more strongly than shallow events. These ground-motion attributes imply that the induced-seismicity hazard is most critical for facilities in

  14. USGS Training in Afghanistan: Modern Earthquake Hazards Assessments

    NASA Astrophysics Data System (ADS)

    Medlin, J. D.; Garthwaite, M.; Holzer, T.; McGarr, A.; Bohannon, R.; Bergen, K.; Vincent, T.

    2007-05-01

    Afghanistan is located in a tectonically active region where ongoing deformation has generated rugged mountainous terrain, and where large earthquakes occur frequently. These earthquakes can present a significant hazard, not only from strong ground shaking, but also from liquefaction and extensive land sliding. The magnitude 6.1 earthquake of March 25, 2002 highlighted the vulnerability of Afghanistan to such hazards, and resulted in over 1000 fatalities. The USGS has provided the first of a series of Earth Science training courses to the Afghan Geological Survey (AGS). This course was concerned with modern earthquake hazard assessments, and is an integral part of a larger USGS effort to provide a comprehensive seismic-hazard assessment for Afghanistan. Funding for these courses is provided by the US Agency for International Development Afghanistan Reconstruction Program. The particular focus of this training course, held December 2-6, 2006 in Kabul, was on providing a background in the seismological and geological methods relevant to preparing for future earthquakes. Topics included identifying active faults, modern tectonic theory, geotechnical measurements of near-surface materials, and strong-motion seismology. With this background, participants may now be expected to educate other members of the community and be actively involved in earthquake hazard assessments themselves. The December, 2006, training course was taught by four lecturers, with all lectures and slides being presented in English and translated into Dari. Copies of the lectures were provided to the students in both hardcopy and digital formats. Class participants included many of the section leaders from within the AGS who have backgrounds in geology, geophysics, and engineering. Two additional training sessions are planned for 2007, the first entitled "Modern Concepts in Geology and Mineral Resource Assessments," and the second entitled "Applied Geophysics for Mineral Resource Assessments."

  15. Earthquake Emergency Education in Dushanbe, Tajikistan

    ERIC Educational Resources Information Center

    Mohadjer, Solmaz; Bendick, Rebecca; Halvorson, Sarah J.; Saydullaev, Umed; Hojiboev, Orifjon; Stickler, Christine; Adam, Zachary R.

    2010-01-01

    We developed a middle school earthquake science and hazards curriculum to promote earthquake awareness to students in the Central Asian country of Tajikistan. These materials include pre- and post-assessment activities, six science activities describing physical processes related to earthquakes, five activities on earthquake hazards and mitigation…

  16. Digital Imaging

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Digital Imaging is the computer processed numerical representation of physical images. Enhancement of images results in easier interpretation. Quantitative digital image analysis by Perceptive Scientific Instruments, locates objects within an image and measures them to extract quantitative information. Applications are CAT scanners, radiography, microscopy in medicine as well as various industrial and manufacturing uses. The PSICOM 327 performs all digital image analysis functions. It is based on Jet Propulsion Laboratory technology, is accurate and cost efficient.

  17. Gravity drives Great Earthquakes

    NASA Astrophysics Data System (ADS)

    Lister, Gordon; Forster, Marnie

    2010-05-01

    The most violent of Great Earthquakes are driven by ruptures on giant megathrusts adjacent to actively forming mountain belts. Current theory suggests that the seismic rupture harvests (and thus releases) elastic energy that has been previously stored in locked segments of the megathrust. The general belief, however, is that this energy was accumulated as the result of relative motion of the adjacent stiff elastic tectonic plates. This mechanism fails to explain many first order aspects of large earthquakes, however. The energy source for strain accumulation must also include gravitational collapse of orogenic crust and/or in the foundering (or roll-back) of an adjacent subducting lithospheric slab. Therefore we have conducted an analysis of the geometry of aftershocks, and report that this allows distinction of two types of failure on giant megathrusts. Mode I failure involves horizontal shortening, and is consistent with the classic view that megathrusts fail in compression, with motion analogous to that expected if accretion takes place against a rigid (or elastic) backstop. Mode II failure involves horizontal extension, and requires the over-riding plate to stretch during an earthquake. This process is likely to continue during the subsequent period of afterslip, and therefore will again be evident in aftershock patterns. Mode I behaviour may well have applied to the southern segment of the Sumatran megathrust, from whence emanated the rupture that drove the 2004 Great Earthquake. Mode II behaviour appears to apply to the northern segment of the same rupture, however. The geometry of aftershocks beneath the Andaman Sea suggest that the crust above the initial rupture failed in an extensional mode. The edge of the Indian plate is foundering, with slab-hinge roll-back in a direction orthogonal to its motion vector. The only possible cause for this extension therefore is westward roll-back of the subducting Indian plate, and the consequent gravity-driven movement

  18. 2010 Chile Earthquake Aftershock Response

    NASA Astrophysics Data System (ADS)

    Barientos, Sergio

    2010-05-01

    The Mw=8.8 earthquake off the coast of Chile on 27 February 2010 is the 5th largest megathrust earthquake ever to be recorded and provides an unprecedented opportunity to advance our understanding of megathrust earthquakes and associated phenomena. The 2010 Chile earthquake ruptured the Concepcion-Constitucion segment of the Nazca/South America plate boundary, south of the Central Chile region and triggered a tsunami along the coast. Following the 2010 earthquake, a very energetic aftershock sequence is being observed in an area that is 600 km along strike from Valparaiso to 150 km south of Concepcion. Within the first three weeks there were over 260 aftershocks with magnitude 5.0 or greater and 18 with magnitude 6.0 or greater (NEIC, USGS). The Concepcion-Constitucion segment lies immediately north of the rupture zone associated with the great magnitude 9.5 Chile earthquake, and south of the 1906 and the 1985 Valparaiso earthquakes. The last great subduction earthquake in the region dates back to the February 1835 event described by Darwin (1871). Since 1835, part of the region was affected in the north by the Talca earthquake in December 1928, interpreted as a shallow dipping thrust event, and by the Chillan earthquake (Mw 7.9, January 1939), a slab-pull intermediate depth earthquake. For the last 30 years, geodetic studies in this area were consistent with a fully coupled elastic loading of the subduction interface at depth; this led to identify the area as a mature seismic gap with potential for an earthquake of magnitude of the order 8.5 or several earthquakes of lesser magnitude. What was less expected was the partial rupturing of the 1985 segment toward north. Today, the 2010 earthquake raises some disturbing questions: Why and how the rupture terminated where it did at the northern end? How did the 2010 earthquake load the adjacent segment to the north and did the 1985 earthquake only partially ruptured the plate interface leaving loaded asperities since

  19. Physics of Earthquake Rupture Propagation

    NASA Astrophysics Data System (ADS)

    Xu, Shiqing; Fukuyama, Eiichi; Sagy, Amir; Doan, Mai-Linh

    2018-05-01

    A comprehensive understanding of earthquake rupture propagation requires the study of not only the sudden release of elastic strain energy during co-seismic slip, but also of other processes that operate at a variety of spatiotemporal scales. For example, the accumulation of the elastic strain energy usually takes decades to hundreds of years, and rupture propagation and termination modify the bulk properties of the surrounding medium that can influence the behavior of future earthquakes. To share recent findings in the multiscale investigation of earthquake rupture propagation, we held a session entitled "Physics of Earthquake Rupture Propagation" during the 2016 American Geophysical Union (AGU) Fall Meeting in San Francisco. The session included 46 poster and 32 oral presentations, reporting observations of natural earthquakes, numerical and experimental simulations of earthquake ruptures, and studies of earthquake fault friction. These presentations and discussions during and after the session suggested a need to document more formally the research findings, particularly new observations and views different from conventional ones, complexities in fault zone properties and loading conditions, the diversity of fault slip modes and their interactions, the evaluation of observational and model uncertainties, and comparison between empirical and physics-based models. Therefore, we organize this Special Issue (SI) of Tectonophysics under the same title as our AGU session, hoping to inspire future investigations. Eighteen articles (marked with "this issue") are included in this SI and grouped into the following six categories.

  20. The physics of an earthquake

    NASA Astrophysics Data System (ADS)

    McCloskey, John

    2008-03-01

    The Sumatra-Andaman earthquake of 26 December 2004 (Boxing Day 2004) and its tsunami will endure in our memories as one of the worst natural disasters of our time. For geophysicists, the scale of the devastation and the likelihood of another equally destructive earthquake set out a series of challenges of how we might use science not only to understand the earthquake and its aftermath but also to help in planning for future earthquakes in the region. In this article a brief account of these efforts is presented. Earthquake prediction is probably impossible, but earth scientists are now able to identify particularly dangerous places for future events by developing an understanding of the physics of stress interaction. Having identified such a dangerous area, a series of numerical Monte Carlo simulations is described which allow us to get an idea of what the most likely consequences of a future earthquake are by modelling the tsunami generated by lots of possible, individually unpredictable, future events. As this article was being written, another earthquake occurred in the region, which had many expected characteristics but was enigmatic in other ways. This has spawned a series of further theories which will contribute to our understanding of this extremely complex problem.

  1. Laboratory investigations of earthquake dynamics

    NASA Astrophysics Data System (ADS)

    Xia, Kaiwen

    In this thesis this will be attempted through controlled laboratory experiments that are designed to mimic natural earthquake scenarios. The earthquake dynamic rupturing process itself is a complicated phenomenon, involving dynamic friction, wave propagation, and heat production. Because controlled experiments can produce results without assumptions needed in theoretical and numerical analysis, the experimental method is thus advantageous over theoretical and numerical methods. Our laboratory fault is composed of carefully cut photoelastic polymer plates (Homahte-100, Polycarbonate) held together by uniaxial compression. As a unique unit of the experimental design, a controlled exploding wire technique provides the triggering mechanism of laboratory earthquakes. Three important components of real earthquakes (i.e., pre-existing fault, tectonic loading, and triggering mechanism) correspond to and are simulated by frictional contact, uniaxial compression, and the exploding wire technique. Dynamic rupturing processes are visualized using the photoelastic method and are recorded via a high-speed camera. Our experimental methodology, which is full-field, in situ, and non-intrusive, has better control and diagnostic capacity compared to other existing experimental methods. Using this experimental approach, we have investigated several problems: dynamics of earthquake faulting occurring along homogeneous faults separating identical materials, earthquake faulting along inhomogeneous faults separating materials with different wave speeds, and earthquake faulting along faults with a finite low wave speed fault core. We have observed supershear ruptures, subRayleigh to supershear rupture transition, crack-like to pulse-like rupture transition, self-healing (Heaton) pulse, and rupture directionality.

  2. Digital printing

    NASA Astrophysics Data System (ADS)

    Sobotka, Werner K.

    1997-02-01

    Digital printing is described as a tool to replace conventional printing machines completely. Still this goal was not reached until now with any of the digital printing technologies to be described in the paper. Productivity and costs are still the main parameters and are not really solved until now. Quality in digital printing is no problem anymore. Definition of digital printing is to transfer digital datas directly on the paper surface. This step can be carried out directly or with the use of an intermediate image carrier. Keywords in digital printing are: computer- to-press; erasable image carrier; image carrier with memory. Digital printing is also the logical development of the new digital area as it is pointed out in Nicholas Negropotes book 'Being Digital' and also the answer to networking and Internet technologies. Creating images text and color in one country and publishing the datas in another country or continent is the main advantage. Printing on demand another big advantage and last but not least personalization the last big advantage. Costs and being able to coop with this new world of prepress technology is the biggest disadvantage. Therefore the very optimistic growth rates for the next few years are really nonexistent. The development of complete new markets is too slow and the replacing of old markets is too small.

  3. Earthquake Prediction in a Big Data World

    NASA Astrophysics Data System (ADS)

    Kossobokov, V. G.

    2016-12-01

    The digital revolution started just about 15 years ago has already surpassed the global information storage capacity of more than 5000 Exabytes (in optimally compressed bytes) per year. Open data in a Big Data World provides unprecedented opportunities for enhancing studies of the Earth System. However, it also opens wide avenues for deceptive associations in inter- and transdisciplinary data and for inflicted misleading predictions based on so-called "precursors". Earthquake prediction is not an easy task that implies a delicate application of statistics. So far, none of the proposed short-term precursory signals showed sufficient evidence to be used as a reliable precursor of catastrophic earthquakes. Regretfully, in many cases of seismic hazard assessment (SHA), from term-less to time-dependent (probabilistic PSHA or deterministic DSHA), and short-term earthquake forecasting (StEF), the claims of a high potential of the method are based on a flawed application of statistics and, therefore, are hardly suitable for communication to decision makers. Self-testing must be done in advance claiming prediction of hazardous areas and/or times. The necessity and possibility of applying simple tools of Earthquake Prediction Strategies, in particular, Error Diagram, introduced by G.M. Molchan in early 1990ies, and Seismic Roulette null-hypothesis as a metric of the alerted space, is evident. The set of errors, i.e. the rates of failure and of the alerted space-time volume, can be easily compared to random guessing, which comparison permits evaluating the SHA method effectiveness and determining the optimal choice of parameters in regard to a given cost-benefit function. These and other information obtained in such a simple testing may supply us with a realistic estimates of confidence and accuracy of SHA predictions and, if reliable but not necessarily perfect, with related recommendations on the level of risks for decision making in regard to engineering design, insurance

  4. Earthquakes and faults in the San Francisco Bay area (1970-2003)

    USGS Publications Warehouse

    Sleeter, Benjamin M.; Calzia, James P.; Walter, Stephen R.; Wong, Florence L.; Saucedo, George J.

    2004-01-01

    The map depicts both active and inactive faults and earthquakes magnitude 1.5 to 7.0 in the greater San Francisco Bay area. Twenty-two earthquakes magnitude 5.0 and greater are indicated on the map and listed chronologically in an accompanying table. The data are compiled from records from 1970-2003. The bathymetry was generated from a digital version of NOAA maps and hydrogeographic data for San Francisco Bay. Elevation data are from the USGS National Elevation Database. Landsat satellite image is from seven Landsat 7 Enhanced Thematic Mapper Plus scenes. Fault data are reproduced with permission from the California Geological Survey. The earthquake data are from the Northern California Earthquake Catalog.

  5. Spatiotemporal evolution of the completeness magnitude of the Icelandic earthquake catalogue from 1991 to 2013

    NASA Astrophysics Data System (ADS)

    Panzera, Francesco; Mignan, Arnaud; Vogfjörð, Kristin S.

    2017-07-01

    In 1991, a digital seismic monitoring network was installed in Iceland with a digital seismic system and automatic operation. After 20 years of operation, we explore for the first time its nationwide performance by analysing the spatiotemporal variations of the completeness magnitude. We use the Bayesian magnitude of completeness (BMC) method that combines local completeness magnitude observations with prior information based on the density of seismic stations. Additionally, we test the impact of earthquake location uncertainties on the BMC results, by filtering the catalogue using a multivariate analysis that identifies outliers in the hypocentre error distribution. We find that the entire North-to-South active rift zone shows a relatively low magnitude of completeness Mc in the range 0.5-1.0, highlighting the ability of the Icelandic network to detect small earthquakes. This work also demonstrates the influence of earthquake location uncertainties on the spatiotemporal magnitude of completeness analysis.

  6. The threat of silent earthquakes

    USGS Publications Warehouse

    Cervelli, Peter

    2004-01-01

    Not all earthquakes shake the ground. The so-called silent types are forcing scientists to rethink their understanding of the way quake-prone faults behave. In rare instances, silent earthquakes that occur along the flakes of seaside volcanoes may cascade into monstrous landslides that crash into the sea and trigger towering tsunamis. Silent earthquakes that take place within fault zones created by one tectonic plate diving under another may increase the chance of ground-shaking shocks. In other locations, however, silent slip may decrease the likelihood of destructive quakes, because they release stress along faults that might otherwise seem ready to snap.

  7. Earthquakes, November-December 1977

    USGS Publications Warehouse

    Person, W.J.

    1978-01-01

    In the United States, the largest earthquake during this reporting period was a magntidue 6.6 in the Andreanof Islands, which are part of the Aleutian Islands chain, on November 4 that caused some minor damage. Northern California was struck by a magnitude 4.8 earthquake on November 22 causing moderate damage in the Willits area. This was the most damaging quake in the United States during the year. Two major earthquakes of magntidues 7.0 or above to 14 for the year. 

  8. The Pocatello Valley, Idaho, earthquake

    USGS Publications Warehouse

    Rogers, A. M.; Langer, C.J.; Bucknam, R.C.

    1975-01-01

    A Richter magnitude 6.3 earthquake occurred at 8:31 p.m mountain daylight time on March 27, 1975, near the Utah-Idaho border in Pocatello Valley. The epicenter of the main shock was located at 42.094° N, 112.478° W, and had a focal depth of 5.5 km. This earthquake was the largest in the continental United States since the destructive San Fernando earthquake of February 1971. The main shock was preceded by a magnitude 4.5 foreshock on March 26. 

  9. Earthquake damage to transportation systems

    USGS Publications Warehouse

    McCullough, Heather

    1994-01-01

    Earthquakes represent one of the most destructive natural hazards known to man. A large magnitude earthquake near a populated area can affect residents over thousands of square kilometers and cause billions of dollars in property damage. Such an event can kill or injure thousands of residents and disrupt the socioeconomic environment for months, sometimes years. A serious result of a large-magnitude earthquake is the disruption of transportation systems, which limits post-disaster emergency response. Movement of emergency vehicles, such as police cars, fire trucks and ambulances, is often severely restricted. Damage to transportation systems is categorized below by cause including: ground failure, faulting, vibration damage, and tsunamis.

  10. USGS Earthquake Program GPS Use Case : Earthquake Early Warning

    DOT National Transportation Integrated Search

    2015-03-12

    USGS GPS receiver use case. Item 1 - High Precision User (federal agency with Stafford Act hazard alert responsibilities for earthquakes, volcanoes and landslides nationwide). Item 2 - Description of Associated GPS Application(s): The USGS Eart...

  11. Nonextensive models for earthquakes.

    PubMed

    Silva, R; França, G S; Vilar, C S; Alcaniz, J S

    2006-02-01

    We have revisited the fragment-asperity interaction model recently introduced by Sotolongo-Costa and Posadas [Phy. Rev. Lett. 92, 048501 (2004)] by considering a different definition for mean values in the context of Tsallis nonextensive statistics and introducing a scale between the earthquake energy and the size of fragment epsilon proportional to r3. The energy-distribution function (EDF) deduced in our approach is considerably different from the one obtained in the above reference. We have also tested the viability of this EDF with data from two different catalogs (in three different areas), namely, the NEIC and the Bulletin Seismic of the Revista Brasileira de Geofísica. Although both approaches provide very similar values for the nonextensive parameter , other physical quantities, e.g., energy density, differ considerably by several orders of magnitude.

  12. Nonextensive models for earthquakes

    SciTech Connect

    Silva, R.; Franca, G.S.; Vilar, C.S.

    2006-02-15

    We have revisited the fragment-asperity interaction model recently introduced by Sotolongo-Costa and Posadas [Phy. Rev. Lett. 92, 048501 (2004)] by considering a different definition for mean values in the context of Tsallis nonextensive statistics and introducing a scale between the earthquake energy and the size of fragment {epsilon}{proportional_to}r{sup 3}. The energy-distribution function (EDF) deduced in our approach is considerably different from the one obtained in the above reference. We have also tested the viability of this EDF with data from two different catalogs (in three different areas), namely, the NEIC and the Bulletin Seismic of the Revista Brasileira de Geofisica.more » Although both approaches provide very similar values for the nonextensive parameter q, other physical quantities, e.g., energy density, differ considerably by several orders of magnitude.« less

  13. Earthquakes - on the moon

    NASA Technical Reports Server (NTRS)

    Nakamura, Y.

    1981-01-01

    Information obtained with the Apollo lunar seismic stations is discussed. The four types of natural seismic sources that have been identified are described, viz., thermal moonquakes, deep moonquakes, meteoroid impacts, and shallow moonquakes. It is suggested that: (1) the thermal quakes represent the slow cracking and movement of surface rocks; (2) the deep quakes are induced by the tide-generating force of the earth's gravity; (3) the meteoroids responsible for most of the observed impacts are in the mass range from 1 to 100 kg and are clustered in groups near the earth's orbit; and (4) the shallow quakes are similar to intraplate earthquakes and indicate that the moon is as seismically active as the interior regions of the earth's tectonic plates. The structure of the lunar interior as inferred from seismic signals due to both the last three natural sources and 'artificial' impacts of used spacecraft is examined in detail.

  14. Preliminary Results of Earthquake-Induced Building Damage Detection with Object-Based Image Classification

    NASA Astrophysics Data System (ADS)

    Sabuncu, A.; Uca Avci, Z. D.; Sunar, F.

    2016-06-01

    Earthquakes are the most destructive natural disasters, which result in massive loss of life, infrastructure damages and financial losses. Earthquake-induced building damage detection is a very important step after earthquakes since earthquake-induced building damage is one of the most critical threats to cities and countries in terms of the area of damage, rate of collapsed buildings, the damage grade near the epicenters and also building damage types for all constructions. Van-Ercis (Turkey) earthquake (Mw= 7.1) was occurred on October 23th, 2011; at 10:41 UTC (13:41 local time) centered at 38.75 N 43.36 E that places the epicenter about 30 kilometers northern part of the city of Van. It is recorded that, 604 people died and approximately 4000 buildings collapsed or seriously damaged by the earthquake. In this study, high-resolution satellite images of Van-Ercis, acquired by Quickbird-2 (Digital Globe Inc.) after the earthquake, were used to detect the debris areas using an object-based image classification. Two different land surfaces, having homogeneous and heterogeneous land covers, were selected as case study areas. As a first step of the object-based image processing, segmentation was applied with a convenient scale parameter and homogeneity criterion parameters. As a next step, condition based classification was used. In the final step of this preliminary study, outputs were compared with streetview/ortophotos for the verification and evaluation of the classification accuracy.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Sichuan Earthquake in China

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Sichuan earthquake in China occurred on May 12, 2008, along faults within the mountains, but near and almost parallel the mountain front, northwest of the city of Chengdu. This major quake caused immediate and severe damage to many villages and cities in the area. Aftershocks pose a continuing danger, but another continuing hazard is the widespread occurrence of landslides that have formed new natural dams and consequently new lakes. These lakes are submerging roads and flooding previously developed lands. But an even greater concern is the possible rapid release of water as the lakes eventually overflow the new dams. The dams are generally composed of disintegrated rock debris that may easily erode, leading to greater release of water, which may then cause faster erosion and an even greater release of water. This possible 'positive feedback' between increasing erosion and increasing water release could result in catastrophic debris flows and/or flooding. The danger is well known to the Chinese earthquake response teams, which have been building spillways over some of the new natural dams.

    This ASTER image, acquired on June 1, 2008, shows two of the new large landslide dams and lakes upstream from the town of Chi-Kua-Kan at 32o12'N latitude and 104o50'E longitude. Vegetation is green, water is blue, and soil is grayish brown in this enhanced color view. New landslides appear bright off-white. The northern (top) lake is upstream from the southern lake. Close inspection shows a series of much smaller lakes in an elongated 'S' pattern along the original stream path. Note especially the large landslides that created the dams. Some other landslides in this area, such as the large one in the northeast corner of the image, occur only on the mountain slopes, so do not block streams, and do not form lakes.

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

    USGS Publications Warehouse

    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.

  18. How citizen seismology is transforming rapid public earthquake information and interactions between seismologists and society

    NASA Astrophysics Data System (ADS)

    Bossu, Rémy; Steed, Robert; Mazet-Roux, Gilles; Roussel, Fréderic; Caroline, Etivant

    2015-04-01

    Historical earthquakes are only known to us through written recollections and so seismologists have a long experience of interpreting the reports of eyewitnesses, explaining probably why seismology has been a pioneer in crowdsourcing and citizen science. Today, Internet has been transforming this situation; It can be considered as the digital nervous system comprising of digital veins and intertwined sensors that capture the pulse of our planet in near real-time. How can both seismology and public could benefit from this new monitoring system? This paper will present the strategy implemented at Euro-Mediterranean Seismological Centre (EMSC) to leverage this new nervous system to detect and diagnose the impact of earthquakes within minutes rather than hours and how it transformed information systems and interactions with the public. We will show how social network monitoring and flashcrowds (massive website traffic increases on EMSC website) are used to automatically detect felt earthquakes before seismic detections, how damaged areas can me mapped through concomitant loss of Internet sessions (visitors being disconnected) and the benefit of collecting felt reports and geolocated pictures to further constrain rapid impact assessment of global earthquakes. We will also describe how public expectations within tens of seconds of ground shaking are at the basis of improved diversified information tools which integrate this user generated contents. A special attention will be given to LastQuake, the most complex and sophisticated Twitter QuakeBot, smartphone application and browser add-on, which deals with the only earthquakes that matter for the public: the felt and damaging earthquakes. In conclusion we will demonstrate that eyewitnesses are today real time earthquake sensors and active actors of rapid earthquake information.

  19. Unraveling earthquake stresses: Insights from dynamically triggered and induced earthquakes

    NASA Astrophysics Data System (ADS)

    Velasco, A. A.; Alfaro-Diaz, R. A.

    2017-12-01

    Induced seismicity, earthquakes caused by anthropogenic activity, has more than doubled in the last several years resulting from practices related to oil and gas production. Furthermore, large earthquakes have been shown to promote the triggering of other events within two fault lengths (static triggering), due to static stresses caused by physical movement along the fault, and also remotely from the passage of seismic waves (dynamic triggering). Thus, in order to understand the mechanisms for earthquake failure, we investigate regions where natural, induced, and dynamically triggered events occur, and specifically target Oklahoma. We first analyze data from EarthScope's USArray Transportable Array (TA) and local seismic networks implementing an optimized (STA/LTA) detector in order to develop local detection and earthquake catalogs. After we identify triggered events through statistical analysis, and perform a stress analysis to gain insight on the stress-states leading to triggered earthquake failure. We use our observations to determine the role of different transient stresses in contributing to natural and induced seismicity by comparing these stresses to regional stress orientation. We also delineate critically stressed regions of triggered seismicity that may indicate areas susceptible to earthquake hazards associated with sustained fluid injection in provinces of induced seismicity. Anthropogenic injection and extraction activity can alter the stress state and fluid flow within production basins. By analyzing the stress release of these ancient faults caused by dynamic stresses, we may be able to determine if fluids are solely responsible for increased seismic activity in induced regions.

  20. Digital Roundup

    ERIC Educational Resources Information Center

    Horn, Michael B.

    2013-01-01

    State policy is crucial to the spread of digital-learning opportunities at the elementary and secondary level. A review of recent legislative action reveals policies that are constantly in flux and differ quite markedly from one state to another. Some have hoped for model digital-learning legislation that could handle all the various issues…

  1. Digital Discrimination

    ERIC Educational Resources Information Center

    Blansett, Jim

    2008-01-01

    In recent years, the Internet has become a digital commons of commerce and education. However, accessibility standards have often been overlooked online, and the digital equivalents to curb-cuts and other physical accommodations have only rarely been implemented to serve those with print disabilities. (A print disability can be a learning…

  2. Digital Ratiometer

    NASA Technical Reports Server (NTRS)

    Beer, R.

    1985-01-01

    Small, low-cost comparator with 24-bit-precision yields ratio signal from pair of analog or digital input signals. Arithmetic logic chips (bit-slice) sample two 24-bit analog-to-digital converters approximately once every millisecond and accumulate them in two 24-bit registers. Approach readily modified to arbitrary precision.

  3. Digital TMI

    NASA Technical Reports Server (NTRS)

    Rios, Joseph

    2012-01-01

    Presenting the current status of the Digital TMI project to visiting members of the FAA Command Center. Digital TMI is an effort to store national-level traffic management initiatives in a standards-compliant manner. Work is funded by the FAA.

  4. Sociological aspects of earthquake prediction

    USGS Publications Warehouse

    Spall, H.

    1979-01-01

    Henry Spall talked recently with Denis Mileti who is in the Department of Sociology, Colorado State University, Fort Collins, Colo. Dr. Mileti is a sociologst involved with research programs that study the socioeconomic impact of earthquake prediction. 

  5. The next new Madrid earthquake

    SciTech Connect

    Atkinson, W.

    1988-01-01

    Scientists who specialize in the study of Mississippi Valley earthquakes say that the region is overdue for a powerful tremor that will cause major damage and undoubtedly some casualties. The inevitability of a future quake and the lack of preparation by both individuals and communities provided the impetus for this book. It brings together applicable information from many disciplines: history, geology and seismology, engineering, zoology, politics and community planning, economics, environmental science, sociology, and psychology and mental health to provide a perspective of the myriad impacts of a major earthquake on the Mississippi Valley. The author addresses such basic questionsmore » as What, actually, are earthquakes How do they occur Can they be predicted, perhaps even prevented He also addresses those steps that individuals can take to improve their chances for survival both during and after an earthquake.« less

  6. Centrality in earthquake multiplex networks

    NASA Astrophysics Data System (ADS)

    Lotfi, Nastaran; Darooneh, Amir Hossein; Rodrigues, Francisco A.

    2018-06-01

    Seismic time series has been mapped as a complex network, where a geographical region is divided into square cells that represent the nodes and connections are defined according to the sequence of earthquakes. In this paper, we map a seismic time series to a temporal network, described by a multiplex network, and characterize the evolution of the network structure in terms of the eigenvector centrality measure. We generalize previous works that considered the single layer representation of earthquake networks. Our results suggest that the multiplex representation captures better earthquake activity than methods based on single layer networks. We also verify that the regions with highest seismological activities in Iran and California can be identified from the network centrality analysis. The temporal modeling of seismic data provided here may open new possibilities for a better comprehension of the physics of earthquakes.

  7. The nature of earthquake prediction

    USGS Publications Warehouse

    Lindh, A.G.

    1991-01-01

    Earthquake prediction is inherently statistical. Although some people continue to think of earthquake prediction as the specification of the time, place, and magnitude of a future earthquake, it has been clear for at least a decade that this is an unrealistic and unreasonable definition. the reality is that earthquake prediction starts from the long-term forecasts of place and magnitude, with very approximate time constraints, and progresses, at least in principle, to a gradual narrowing of the time window as data and understanding permit. Primitive long-term forecasts are clearly possible at this time on a few well-characterized fault systems. Tightly focuses monitoring experiments aimed at short-term prediction are already underway in Parkfield, California, and in the Tokai region in Japan; only time will tell how much progress will be possible. 

  8. Earthquakes, May-June, 1992

    USGS Publications Warehouse

    Person, Waverly J.

    1992-01-01

    The months of May and June were very active in terms of earthquake occurrence. Six major earthquakes (7.0earthquakes included a magnitude 7.1 in Papua New Guinea on May 15, a magnitude 7.1 followed by a magnitude 7.5 in the Philippine Islands on May 17, a magnitude 7.0 in the Cuba region on May 25, and a magnitude 7.3 in the Santa Cruz Islands of the Pacific on May 27. In the United States, a magnitude 7.6 earthquake struck in southern California on June 28 followed by a magnitude 6.7 quake about three hours later.

  9. Geochemical challenge to earthquake prediction.

    PubMed Central

    Wakita, H

    1996-01-01

    The current status of geochemical and groundwater observations for earthquake prediction in Japan is described. The development of the observations is discussed in relation to the progress of the earthquake prediction program in Japan. Three major findings obtained from our recent studies are outlined. (i) Long-term radon observation data over 18 years at the SKE (Suikoen) well indicate that the anomalous radon change before the 1978 Izu-Oshima-kinkai earthquake can with high probability be attributed to precursory changes. (ii) It is proposed that certain sensitive wells exist which have the potential to detect precursory changes. (iii) The appearance and nonappearance of coseismic radon drops at the KSM (Kashima) well reflect changes in the regional stress state of an observation area. In addition, some preliminary results of chemical changes of groundwater prior to the 1995 Kobe (Hyogo-ken nanbu) earthquake are presented. PMID:11607665

  10. Earthquakes, September-October, 1979

    USGS Publications Warehouse

    Person, W.J.

    1980-01-01

    In the United States, California experienced the strongest earthquake in that State since 1971. The quake, a M=6.8, occurred on October 15, in Baja California, Mexico, near the California border and caused injuries and damage. 

  11. Earthquakes in Stable Continental Crust.

    ERIC Educational Resources Information Center

    Johnston, Arch C.; Kanter, Lisa R.

    1990-01-01

    Discussed are some of the reasons for earthquakes which occur in stable crust away from familiar zones at the ends of tectonic plates. Crust stability and the reactivation of old faults are described using examples from India and Australia. (CW)

  12. Mitigating earthquakes; the federal role

    USGS Publications Warehouse

    Press, F.

    1977-01-01

    With rapid approach of a capability to make reliable earthquake forecasts, it essential that the Federal Government play a strong, positive role in formulating and implementing plans to reduce earthquake hazards. Many steps are being taken in this direction, with the President looking to the Office of Science and Technology Policy (OSTP) in his Executive Office to provide leadership in establishing and coordinating Federal activities. 

  13. Post-earthquake dilatancy recovery

    NASA Technical Reports Server (NTRS)

    Scholz, C. H.

    1974-01-01

    Geodetic measurements of the 1964 Niigata, Japan earthquake and of three other examples are briefly examined. They show exponentially decaying subsidence for a year after the quakes. The observations confirm the dilatancy-fluid diffusion model of earthquake precursors and clarify the extent and properties of the dilatant zone. An analysis using one-dimensional consolidation theory is included which agrees well with this interpretation.

  14. Earthquake Triggering in the September 2017 Mexican Earthquake Sequence

    NASA Astrophysics Data System (ADS)

    Fielding, E. J.; Gombert, B.; Duputel, Z.; Huang, M. H.; Liang, C.; Bekaert, D. P.; Moore, A. W.; Liu, Z.; Ampuero, J. P.

    2017-12-01

    Southern Mexico was struck by four earthquakes with Mw > 6 and numerous smaller earthquakes in September 2017, starting with the 8 September Mw 8.2 Tehuantepec earthquake beneath the Gulf of Tehuantepec offshore Chiapas and Oaxaca. We study whether this M8.2 earthquake triggered the three subsequent large M>6 quakes in southern Mexico to improve understanding of earthquake interactions and time-dependent risk. All four large earthquakes were extensional despite the the subduction of the Cocos plate. The traditional definition of aftershocks: likely an aftershock if it occurs within two rupture lengths of the main shock soon afterwards. Two Mw 6.1 earthquakes, one half an hour after the M8.2 beneath the Tehuantepec gulf and one on 23 September near Ixtepec in Oaxaca, both fit as traditional aftershocks, within 200 km of the main rupture. The 19 September Mw 7.1 Puebla earthquake was 600 km away from the M8.2 shock, outside the standard aftershock zone. Geodetic measurements from interferometric analysis of synthetic aperture radar (InSAR) and time-series analysis of GPS station data constrain finite fault total slip models for the M8.2, M7.1, and M6.1 Ixtepec earthquakes. The early M6.1 aftershock was too close in time and space to the M8.2 to measure with InSAR or GPS. We analyzed InSAR data from Copernicus Sentinel-1A and -1B satellites and JAXA ALOS-2 satellite. Our preliminary geodetic slip model for the M8.2 quake shows significant slip extended > 150 km NW from the hypocenter, longer than slip in the v1 finite-fault model (FFM) from teleseismic waveforms posted by G. Hayes at USGS NEIC. Our slip model for the M7.1 earthquake is similar to the v2 NEIC FFM. Interferograms for the M6.1 Ixtepec quake confirm the shallow depth in the upper-plate crust and show centroid is about 30 km SW of the NEIC epicenter, a significant NEIC location bias, but consistent with cluster relocations (E. Bergman, pers. comm.) and with Mexican SSN location. Coulomb static stress

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

    USGS Publications Warehouse

    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.

  16. Global earthquake fatalities and population

    USGS Publications Warehouse

    Holzer, Thomas L.; Savage, James C.

    2013-01-01

    Modern global earthquake fatalities can be separated into two components: (1) fatalities from an approximately constant annual background rate that is independent of world population growth and (2) fatalities caused by earthquakes with large human death tolls, the frequency of which is dependent on world population. Earthquakes with death tolls greater than 100,000 (and 50,000) have increased with world population and obey a nonstationary Poisson distribution with rate proportional to population. We predict that the number of earthquakes with death tolls greater than 100,000 (50,000) will increase in the 21st century to 8.7±3.3 (20.5±4.3) from 4 (7) observed in the 20th century if world population reaches 10.1 billion in 2100. Combining fatalities caused by the background rate with fatalities caused by catastrophic earthquakes (>100,000 fatalities) indicates global fatalities in the 21st century will be 2.57±0.64 million if the average post-1900 death toll for catastrophic earthquakes (193,000) is assumed.

  17. Large earthquakes and creeping faults

    USGS Publications Warehouse

    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.

  18. Evidence for Ancient Mesoamerican Earthquakes

    NASA Astrophysics Data System (ADS)

    Kovach, R. L.; Garcia, B.

    2001-12-01

    Evidence for past earthquake damage at Mesoamerican ruins is often overlooked because of the invasive effects of tropical vegetation and is usually not considered as a casual factor when restoration and reconstruction of many archaeological sites are undertaken. Yet the proximity of many ruins to zones of seismic activity would argue otherwise. Clues as to the types of damage which should be soughtwere offered in September 1999 when the M = 7.5 Oaxaca earthquake struck the ruins of Monte Alban, Mexico, where archaeological renovations were underway. More than 20 structures were damaged, 5 of them seriously. Damage features noted were walls out of plumb, fractures in walls, floors, basal platforms and tableros, toppling of columns, and deformation, settling and tumbling of walls. A Modified Mercalli Intensity of VII (ground accelerations 18-34 %b) occurred at the site. Within the diffuse landward extension of the Caribbean plate boundary zone M = 7+ earthquakes occur with repeat times of hundreds of years arguing that many Maya sites were subjected to earthquakes. Damage to re-erected and reinforced stelae, walls, and buildings were witnessed at Quirigua, Guatemala, during an expedition underway when then 1976 M = 7.5 Guatemala earthquake on the Motagua fault struck. Excavations also revealed evidence (domestic pttery vessels and skeleton of a child crushed under fallen walls) of an ancient earthquake occurring about the teim of the demise and abandonment of Quirigua in the late 9th century. Striking evidence for sudden earthquake building collapse at the end of the Mayan Classic Period ~A.D. 889 was found at Benque Viejo (Xunantunich), Belize, located 210 north of Quirigua. It is argued that a M = 7.5 to 7.9 earthquake at the end of the Maya Classic period centered in the vicinity of the Chixoy-Polochic and Motagua fault zones cound have produced the contemporaneous earthquake damage to the above sites. As a consequences this earthquake may have accelerated the

  19. Earthquake Potential Models for China

    NASA Astrophysics Data System (ADS)

    Rong, Y.; Jackson, D. D.

    2002-12-01

    We present three earthquake potential estimates for magnitude 5.4 and larger earthquakes for China. The potential is expressed as the rate density (probability per unit area, magnitude and time). The three methods employ smoothed seismicity-, geologic slip rate-, and geodetic strain rate data. We tested all three estimates, and the published Global Seismic Hazard Assessment Project (GSHAP) model, against earthquake data. We constructed a special earthquake catalog which combines previous catalogs covering different times. We used the special catalog to construct our smoothed seismicity model and to evaluate all models retrospectively. All our models employ a modified Gutenberg-Richter magnitude distribution with three parameters: a multiplicative ``a-value," the slope or ``b-value," and a ``corner magnitude" marking a strong decrease of earthquake rate with magnitude. We assumed the b-value to be constant for the whole study area and estimated the other parameters from regional or local geophysical data. The smoothed seismicity method assumes that the rate density is proportional to the magnitude of past earthquakes and approximately as the reciprocal of the epicentral distance out to a few hundred kilometers. We derived the upper magnitude limit from the special catalog and estimated local a-values from smoothed seismicity. Earthquakes since January 1, 2000 are quite compatible with the model. For the geologic forecast we adopted the seismic source zones (based on geological, geodetic and seismicity data) of the GSHAP model. For each zone, we estimated a corner magnitude by applying the Wells and Coppersmith [1994] relationship to the longest fault in the zone, and we determined the a-value from fault slip rates and an assumed locking depth. The geological model fits the earthquake data better than the GSHAP model. We also applied the Wells and Coppersmith relationship to individual faults, but the results conflicted with the earthquake record. For our geodetic

  20. Comparison of two large earthquakes: the 2008 Sichuan Earthquake and the 2011 East Japan Earthquake.

    PubMed

    Otani, Yuki; Ando, Takayuki; Atobe, Kaori; Haiden, Akina; Kao, Sheng-Yuan; Saito, Kohei; Shimanuki, Marie; Yoshimoto, Norifumi; Fukunaga, Koichi

    2012-01-01

    Between August 15th and 19th, 2011, eight 5th-year medical students from the Keio University School of Medicine had the opportunity to visit the Peking University School of Medicine and hold a discussion session titled "What is the most effective way to educate people for survival in an acute disaster situation (before the mental health care stage)?" During the session, we discussed the following six points: basic information regarding the Sichuan Earthquake and the East Japan Earthquake, differences in preparedness for earthquakes, government actions, acceptance of medical rescue teams, earthquake-induced secondary effects, and media restrictions. Although comparison of the two earthquakes was not simple, we concluded that three major points should be emphasized to facilitate the most effective course of disaster planning and action. First, all relevant agencies should formulate emergency plans and should supply information regarding the emergency to the general public and health professionals on a normal basis. Second, each citizen should be educated and trained in how to minimize the risks from earthquake-induced secondary effects. Finally, the central government should establish a single headquarters responsible for command, control, and coordination during a natural disaster emergency and should centralize all powers in this single authority. We hope this discussion may be of some use in future natural disasters in China, Japan, and worldwide.

  1. Volunteers in the earthquake hazard reduction program

    USGS Publications Warehouse

    Ward, P.L.

    1978-01-01

    With this in mind, I organized a small workshop for approximately 30 people on February 2 and 3, 1978, in Menlo Park, Calif. the purpose of the meeting was to discuss methods of involving volunteers in a meaningful way in earthquake research and in educating the public about earthquake hazards. The emphasis was on earthquake prediction research, but the discussions covered the whole earthquake hazard reduction program. Representatives attended from the earthquake research community, from groups doing socioeconomic research on earthquake matters, and from a wide variety of organizations who might sponsor volunteers. 

  2. An Interactive Program on Digitizing Historical Seismograms

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Xu, T.

    2013-12-01

    Retrieving information from historical seismograms is of great importance since they are considered the unique sources that provide quantitative information of historical earthquakes. Modern techniques of seismology require digital forms of seismograms that are essentially a sequence of time-amplitude pairs. However, the historical seismograms, after scanned into computers, are two dimensional arrays. Each element of the arrays contains the grayscale value or RGB value of the corresponding pixel. The problem of digitizing historical seismograms, referred to as converting historical seismograms to digital seismograms, can be formulated as an inverse problem that generating sequences of time-amplitude pairs from a two dimension arrays. This problem has infinite solutions. The algorithm for automatic digitization of historical seismogram presented considers several features of seismograms, including continuity, smoothness of the seismic traces as the prior information, and assumes that the amplitude is a single-valued function of time. An interactive program based on the algorithm is also presented. The program is developed using Matlab GUI and has both automatic and manual modality digitization. Users can easily switch between them, and try different combinations to get the optimal results. Several examples are given to illustrate the results of digitizing seismograms using the program, including a photographic record and a wide-angle reflection/refraction seismogram. Digitized result of the program (redrawn using Golden Software Surfer for high resolution image). (a) shows the result of automatic digitization, and (b) is the result after manual correction.

  3. Computer simulation of earthquakes

    NASA Technical Reports Server (NTRS)

    Cohen, S. C.

    1976-01-01

    Two computer simulation models of earthquakes were studied for the dependence of the pattern of events on the model assumptions and input parameters. Both models represent the seismically active region by mechanical blocks which are connected to one another and to a driving plate. The blocks slide on a friction surface. In the first model elastic forces were employed and time independent friction to simulate main shock events. The size, length, and time and place of event occurrence were influenced strongly by the magnitude and degree of homogeniety in the elastic and friction parameters of the fault region. Periodically reoccurring similar events were frequently observed in simulations with near homogeneous parameters along the fault, whereas, seismic gaps were a common feature of simulations employing large variations in the fault parameters. The second model incorporated viscoelastic forces and time-dependent friction to account for aftershock sequences. The periods between aftershock events increased with time and the aftershock region was confined to that which moved in the main event.

  4. Reconsidering earthquake scaling

    USGS Publications Warehouse

    Gomberg, Joan S.; Wech, Aaron G.; Creager, Kenneth; Obara, K.; Agnew, Duncan

    2016-01-01

    The relationship (scaling) between scalar moment, M0, and duration, T, potentially provides key constraints on the physics governing fault slip. The prevailing interpretation of M0-T observations proposes different scaling for fast (earthquakes) and slow (mostly aseismic) slip populations and thus fundamentally different driving mechanisms. We show that a single model of slip events within bounded slip zones may explain nearly all fast and slow slip M0-T observations, and both slip populations have a change in scaling, where the slip area growth changes from 2-D when too small to sense the boundaries to 1-D when large enough to be bounded. We present new fast and slow slip M0-T observations that sample the change in scaling in each population, which are consistent with our interpretation. We suggest that a continuous but bimodal distribution of slip modes exists and M0-T observations alone may not imply a fundamental difference between fast and slow slip.

  5. Laboratory generated M -6 earthquakes

    USGS Publications Warehouse

    McLaskey, Gregory C.; Kilgore, Brian D.; Lockner, David A.; Beeler, Nicholas M.

    2014-01-01

    We consider whether mm-scale earthquake-like seismic events generated in laboratory experiments are consistent with our understanding of the physics of larger earthquakes. This work focuses on a population of 48 very small shocks that are foreshocks and aftershocks of stick–slip events occurring on a 2.0 m by 0.4 m simulated strike-slip fault cut through a large granite sample. Unlike the larger stick–slip events that rupture the entirety of the simulated fault, the small foreshocks and aftershocks are contained events whose properties are controlled by the rigidity of the surrounding granite blocks rather than characteristics of the experimental apparatus. The large size of the experimental apparatus, high fidelity sensors, rigorous treatment of wave propagation effects, and in situ system calibration separates this study from traditional acoustic emission analyses and allows these sources to be studied with as much rigor as larger natural earthquakes. The tiny events have short (3–6 μs) rise times and are well modeled by simple double couple focal mechanisms that are consistent with left-lateral slip occurring on a mm-scale patch of the precut fault surface. The repeatability of the experiments indicates that they are the result of frictional processes on the simulated fault surface rather than grain crushing or fracture of fresh rock. Our waveform analysis shows no significant differences (other than size) between the M -7 to M -5.5 earthquakes reported here and larger natural earthquakes. Their source characteristics such as stress drop (1–10 MPa) appear to be entirely consistent with earthquake scaling laws derived for larger earthquakes.

  6. Security Implications of Induced Earthquakes

    NASA Astrophysics Data System (ADS)

    Jha, B.; Rao, A.

    2016-12-01

    The increase in earthquakes induced or triggered by human activities motivates us to research how a malicious entity could weaponize earthquakes to cause damage. Specifically, we explore the feasibility of controlling the location, timing and magnitude of an earthquake by activating a fault via injection and production of fluids into the subsurface. Here, we investigate the relationship between the magnitude and trigger time of an induced earthquake to the well-to-fault distance. The relationship between magnitude and distance is important to determine the farthest striking distance from which one could intentionally activate a fault to cause certain level of damage. We use our novel computational framework to model the coupled multi-physics processes of fluid flow and fault poromechanics. We use synthetic models representative of the New Madrid Seismic Zone and the San Andreas Fault Zone to assess the risk in the continental US. We fix injection and production flow rates of the wells and vary their locations. We simulate injection-induced Coulomb destabilization of faults and evolution of fault slip under quasi-static deformation. We find that the effect of distance on the magnitude and trigger time is monotonic, nonlinear, and time-dependent. Evolution of the maximum Coulomb stress on the fault provides insights into the effect of the distance on rupture nucleation and propagation. The damage potential of induced earthquakes can be maintained even at longer distances because of the balance between pressure diffusion and poroelastic stress transfer mechanisms. We conclude that computational modeling of induced earthquakes allows us to measure feasibility of weaponzing earthquakes and developing effective defense mechanisms against such attacks.

  7. Earthquake source properties from pseudotachylite

    USGS Publications Warehouse

    Beeler, Nicholas M.; Di Toro, Giulio; Nielsen, Stefan

    2016-01-01

    The motions radiated from an earthquake contain information that can be interpreted as displacements within the source and therefore related to stress drop. Except in a few notable cases, the source displacements can neither be easily related to the absolute stress level or fault strength, nor attributed to a particular physical mechanism. In contrast paleo-earthquakes recorded by exhumed pseudotachylite have a known dynamic mechanism whose properties constrain the co-seismic fault strength. Pseudotachylite can also be used to directly address a longstanding discrepancy between seismologically measured static stress drops, which are typically a few MPa, and much larger dynamic stress drops expected from thermal weakening during localized slip at seismic speeds in crystalline rock [Sibson, 1973; McKenzie and Brune, 1969; Lachenbruch, 1980; Mase and Smith, 1986; Rice, 2006] as have been observed recently in laboratory experiments at high slip rates [Di Toro et al., 2006a]. This note places pseudotachylite-derived estimates of fault strength and inferred stress levels within the context and broader bounds of naturally observed earthquake source parameters: apparent stress, stress drop, and overshoot, including consideration of roughness of the fault surface, off-fault damage, fracture energy, and the 'strength excess'. The analysis, which assumes stress drop is related to corner frequency by the Madariaga [1976] source model, is restricted to the intermediate sized earthquakes of the Gole Larghe fault zone in the Italian Alps where the dynamic shear strength is well-constrained by field and laboratory measurements. We find that radiated energy exceeds the shear-generated heat and that the maximum strength excess is ~16 MPa. More generally these events have inferred earthquake source parameters that are rate, for instance a few percent of the global earthquake population has stress drops as large, unless: fracture energy is routinely greater than existing models allow

  8. Broadband Analysis of the Energetics of Earthquakes and Tsunamis in the Sunda Forearc from 1987-2012

    NASA Astrophysics Data System (ADS)

    Choy, G. L.; Kirby, S. H.; Hayes, G. P.

    2013-12-01

    In the eighteen years before the 2004 Sumatra Mw 9.1 earthquake, the forearc off Sumatra experienced only one large (Mw > 7.0) thrust event and experienced no earthquakes that generated measurable tsunami wave heights. In the subsequent eight years, twelve large thrust earthquakes occurred of which half generated measurable tsunamis. The number of broadband earthquakes (those events with Mw > 5.5 for which broadband teleseismic waveforms have sufficient signal to compute depths, focal mechanisms, moments and radiated energies) jumped six fold after 2004. The progression of tsunami earthquakes, as well as the profuse increase in broadband activity, strongly suggests regional stress adjustments following the Sumatra 2004 megathrust earthquake. Broadband source parameters, published routinely in the Source Parameters (SOPAR) database of the USGS's NEIC (National Earthquake Information Center), have provided the most accurate depths and locations of big earthquakes since the implementation of modern digital seismographic networks. Moreover, radiated energy and seismic moment (also found in SOPAR) are related to apparent stress which is a measure of fault maturity. In mapping apparent stress as a function of depth and focal mechanism, we find that about 12% of broadband thrust earthquakes in the subduction zone are unequivocally above or below the slab interface. Apparent stresses of upper-plate events are associated with failure on mature splay faults, some of which generated measurable tsunamis. One unconventional source for local wave heights was a large intraslab earthquake. High-energy upper-plate events, which are dominant in the Aceh Basin, are associated with immature faults, which may explain why the region was bypassed by significant rupture during the 2004 Sumatra earthquake. The majority of broadband earthquakes are non-randomly concentrated under the outer-arc high. They appear to delineate the periphery of the contiguous rupture zones of large earthquakes

  9. Digital photography

    PubMed Central

    Windsor, J S; Rodway, G W; Middleton, P M; McCarthy, S

    2006-01-01

    Objective The emergence of a new generation of “point‐and‐shoot” digital cameras offers doctors a compact, portable and user‐friendly solution to the recording of highly detailed digital photographs and video images. This work highlights the use of such technology, and provides information for those who wish to record, store and display their own medical images. Methods Over a 3‐month period, a digital camera was carried by a doctor in a busy, adult emergency department and used to record a range of clinical images that were subsequently transferred to a computer database. Results In total, 493 digital images were recorded, of which 428 were photographs and 65 were video clips. These were successfully used for teaching purposes, publications and patient records. Conclusions This study highlights the importance of informed consent, the selection of a suitable package of digital technology and the role of basic photographic technique in developing a successful digital database in a busy clinical environment. PMID:17068281

  10. Protracted fluvial recovery from medieval earthquakes, Pokhara, Nepal

    NASA Astrophysics Data System (ADS)

    Stolle, Amelie; Bernhardt, Anne; Schwanghart, Wolfgang; Andermann, Christoff; Schönfeldt, Elisabeth; Seidemann, Jan; Adhikari, Basanta R.; Merchel, Silke; Rugel, Georg; Fort, Monique; Korup, Oliver

    2016-04-01

    River response to strong earthquake shaking in mountainous terrain often entails the flushing of sediments delivered by widespread co-seismic landsliding. Detailed mass-balance studies following major earthquakes in China, Taiwan, and New Zealand suggest fluvial recovery times ranging from several years to decades. We report a detailed chronology of earthquake-induced valley fills in the Pokhara region of western-central Nepal, and demonstrate that rivers continue to adjust to several large medieval earthquakes to the present day, thus challenging the notion of transient fluvial response to seismic disturbance. The Pokhara valley features one of the largest and most extensively dated sedimentary records of earthquake-triggered sedimentation in the Himalayas, and independently augments paleo-seismological archives obtained mainly from fault trenches and historic documents. New radiocarbon dates from the catastrophically deposited Pokhara Formation document multiple phases of extremely high geomorphic activity between ˜700 and ˜1700 AD, preserved in thick sequences of alternating fluvial conglomerates, massive mud and silt beds, and cohesive debris-flow deposits. These dated fan-marginal slackwater sediments indicate pronounced sediment pulses in the wake of at least three large medieval earthquakes in ˜1100, 1255, and 1344 AD. We combine these dates with digital elevation models, geological maps, differential GPS data, and sediment logs to estimate the extent of these three pulses that are characterized by sedimentation rates of ˜200 mm yr-1 and peak rates as high as 1,000 mm yr-1. Some 5.5 to 9 km3 of material infilled the pre-existing topography, and is now prone to ongoing fluvial dissection along major canyons. Contemporary river incision into the Pokhara Formation is rapid (120-170 mm yr-1), triggering widespread bank erosion, channel changes, and very high sediment yields of the order of 103 to 105 t km-2 yr-1, that by far outweigh bedrock denudation rates

  11. The music of earthquakes and Earthquake Quartet #1

    USGS Publications Warehouse

    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. Digital Collections, Digital Libraries & the Digitization of Cultural Heritage Information.

    ERIC Educational Resources Information Center

    Lynch, Clifford

    2002-01-01

    Discusses digital collections and digital libraries. Topics include broadband availability; digital rights protection; content, both non-profit and commercial; digitization of cultural content; sustainability; metadata harvesting protocol; infrastructure; authorship; linking multiple resources; data mining; digitization of reference works;…

  13. Toward real-time regional earthquake simulation of Taiwan earthquakes

    NASA Astrophysics Data System (ADS)

    Lee, S.; Liu, Q.; Tromp, J.; Komatitsch, D.; Liang, W.; Huang, B.

    2013-12-01

    We developed a Real-time Online earthquake Simulation system (ROS) to simulate regional earthquakes in Taiwan. The ROS uses a centroid moment tensor solution of seismic events from a Real-time Moment Tensor monitoring system (RMT), which provides all the point source parameters including the event origin time, hypocentral location, moment magnitude and focal mechanism within 2 minutes after the occurrence of an earthquake. Then, all of the source parameters are automatically forwarded to the ROS to perform an earthquake simulation, which is based on a spectral-element method (SEM). We have improved SEM mesh quality by introducing a thin high-resolution mesh layer near the surface to accommodate steep and rapidly varying topography. The mesh for the shallow sedimentary basin is adjusted to reflect its complex geometry and sharp lateral velocity contrasts. The grid resolution at the surface is about 545 m, which is sufficient to resolve topography and tomography data for simulations accurate up to 1.0 Hz. The ROS is also an infrastructural service, making online earthquake simulation feasible. Users can conduct their own earthquake simulation by providing a set of source parameters through the ROS webpage. For visualization, a ShakeMovie and ShakeMap are produced during the simulation. The time needed for one event is roughly 3 minutes for a 70 sec ground motion simulation. The ROS is operated online at the Institute of Earth Sciences, Academia Sinica (http://ros.earth.sinica.edu.tw/). Our long-term goal for the ROS system is to contribute to public earth science outreach and to realize seismic ground motion prediction in real-time.

  14. Earthquake and Tsunami booklet based on two Indonesia earthquakes

    NASA Astrophysics Data System (ADS)

    Hayashi, Y.; Aci, M.

    2014-12-01

    Many destructive earthquakes occurred during the last decade in Indonesia. These experiences are very important precepts for the world people who live in earthquake and tsunami countries. We are collecting the testimonies of tsunami survivors to clarify successful evacuation process and to make clear the characteristic physical behaviors of tsunami near coast. We research 2 tsunami events, 2004 Indian Ocean tsunami and 2010 Mentawai slow earthquake tsunami. Many video and photographs were taken by people at some places in 2004 Indian ocean tsunami disaster; nevertheless these were few restricted points. We didn't know the tsunami behavior in another place. In this study, we tried to collect extensive information about tsunami behavior not only in many places but also wide time range after the strong shake. In Mentawai case, the earthquake occurred in night, so there are no impressive photos. To collect detail information about evacuation process from tsunamis, we contrived the interview method. This method contains making pictures of tsunami experience from the scene of victims' stories. In 2004 Aceh case, all survivors didn't know tsunami phenomena. Because there were no big earthquakes with tsunami for one hundred years in Sumatra region, public people had no knowledge about tsunami. This situation was highly improved in 2010 Mentawai case. TV programs and NGO or governmental public education programs about tsunami evacuation are widespread in Indonesia. Many people know about fundamental knowledge of earthquake and tsunami disasters. We made drill book based on victim's stories and painted impressive scene of 2 events. We used the drill book in disaster education event in school committee of west Java. About 80 % students and teachers evaluated that the contents of the drill book are useful for correct understanding.

  15. Earthquake Archaeology: a logical approach?

    NASA Astrophysics Data System (ADS)

    Stewart, I. S.; Buck, V. A.

    2001-12-01

    Ancient earthquakes can leave their mark in the mythical and literary accounts of ancient peoples, the stratigraphy of their site histories, and the structural integrity of their constructions. Within this broad cross-disciplinary tramping ground, earthquake geologists have tended to focus on those aspects of the cultural record that are most familiar to them; the physical effects of seismic deformation on ancient constructions. One of the core difficulties with this 'earthquake archaeology' approach is that recent attempts to isolate structural criteria that are diagnostic or strongly suggestive of a seismic origin are undermined by the recognition that signs of ancient seismicity are generally indistinguishable from non-seismic mechanisms (poor construction, adverse geotechnical conditions). We illustrate the difficulties and inconsistencies in current proposed 'earthquake diagnostic' schemes by reference to two case studies of archaeoseismic damage in central Greece. The first concerns fallen columns at various Classical temple localities in mainland Greece (Nemea, Sounio, Olympia, Bassai) which, on the basis of observed structural criteria, are earthquake-induced but which are alternatively explained by archaeologists as the action of human disturbance. The second re-examines the almost type example of the Kyparissi site in the Atalanti region as a Classical stoa offset across a seismic surface fault, arguing instead for its deformation by ground instability. Finally, in highlighting the inherent ambiguity of archaeoseismic data, we consider the value of a logic-tree approach for quantifying and quantifying our uncertainities for seismic-hazard analysis.

  16. Overview of Historical Earthquake Document Database in Japan and Future Development

    NASA Astrophysics Data System (ADS)

    Nishiyama, A.; Satake, K.

    2014-12-01

    In Japan, damage and disasters from historical large earthquakes have been documented and preserved. Compilation of historical earthquake documents started in the early 20th century and 33 volumes of historical document source books (about 27,000 pages) have been published. However, these source books are not effectively utilized for researchers due to a contamination of low-reliability historical records and a difficulty for keyword searching by characters and dates. To overcome these problems and to promote historical earthquake studies in Japan, construction of text database started in the 21 century. As for historical earthquakes from the beginning of the 7th century to the early 17th century, "Online Database of Historical Documents in Japanese Earthquakes and Eruptions in the Ancient and Medieval Ages" (Ishibashi, 2009) has been already constructed. They investigated the source books or original texts of historical literature, emended the descriptions, and assigned the reliability of each historical document on the basis of written age. Another database compiled the historical documents for seven damaging earthquakes occurred along the Sea of Japan coast in Honshu, central Japan in the Edo period (from the beginning of the 17th century to the middle of the 19th century) and constructed text database and seismic intensity data base. These are now publicized on the web (written only in Japanese). However, only about 9 % of the earthquake source books have been digitized so far. Therefore, we plan to digitize all of the remaining historical documents by the research-program which started in 2014. The specification of the data base will be similar for previous ones. We also plan to combine this database with liquefaction traces database, which will be constructed by other research program, by adding the location information described in historical documents. Constructed database would be utilized to estimate the distributions of seismic intensities and tsunami

  17. The October 12, 1992, Dahshur, Egypt, Earthquake

    USGS Publications Warehouse

    Thenhaus, P.C.; Celebi, M.; Sharp, R.V.

    1993-01-01

    We were part of an international reconnaissance team that investigated the Dahsur earthquake. This article summarizes our findings and points out how even a relatively moderate sized earthquake can cause widespread damage and a large number of casualities. 

  18. Unbonded Prestressed Columns for Earthquake Resistance

    DOT National Transportation Integrated Search

    2012-05-01

    Modern structures are able to survive significant shaking caused by earthquakes. By implementing unbonded post-tensioned tendons in bridge columns, the damage caused by an earthquake can be significantly lower than that of a standard reinforced concr...

  19. St. Louis Area Earthquake Hazards Mapping Project - December 2008-June 2009 Progress Report

    USGS Publications Warehouse

    Williams, R.A.; Bauer, R.A.; Boyd, O.S.; Chung, J.; Cramer, C.H.; Gaunt, D.A.; Hempen, G.L.; Hoffman, D.; McCallister, N.S.; Prewett, J.L.; Rogers, J.D.; Steckel, P.J.; Watkins, C.M.

    2009-01-01

    This report summarizes the mission, the project background, the participants, and the progress of the St. Louis Area Earthquake Hazards Mapping Project (SLAEHMP) for the period from December 2008 through June 2009. During this period, the SLAEHMP held five conference calls and two face-to-face meetings in St. Louis, participated in several earthquake awareness public meetings, held one outreach field trip for the business and government community, collected and compiled new borehole and digital elevation data from partners, and published a project summary.

  20. Incubation of Chile's 1960 Earthquake

    NASA Astrophysics Data System (ADS)

    Atwater, B. F.; Cisternas, M.; Salgado, I.; Machuca, G.; Lagos, M.; Eipert, A.; Shishikura, M.

    2003-12-01

    Infrequent occurrence of giant events may help explain how the 1960 Chile earthquake attained M 9.5. Although old documents imply that this earthquake followed great earthquakes of 1575, 1737 and 1837, only three earthquakes of the past 1000 years produced geologic records like those for 1960. These earlier earthquakes include the 1575 event but not 1737 or 1837. Because the 1960 earthquake had nearly twice the seismic slip expected from plate convergence since 1837, much of the strain released in 1960 may have been accumulating since 1575. Geologic evidence for such incubation comes from new paleoseismic findings at the R¡o Maullin estuary, which indents the Pacific coast at 41.5§ S midway along the 1960 rupture. The 1960 earthquake lowered the area by 1.5 m, and the ensuing tsunami spread sand across lowland soils. The subsidence killed forests and changed pastures into sandy tidal flats. Guided by these 1960 analogs, we inferred tsunami and earthquake history from sand sheets, tree rings, and old maps. At Chuyaquen, 10 km upriver from the sea, we studied sand sheets in 31 backhoe pits on a geologic transect 1 km long. Each sheet overlies the buried soil of a former marsh or meadow. The sand sheet from 1960 extends the entire length of the transect. Three earlier sheets can be correlated at least half that far. The oldest one, probably a tsunami deposit, surrounds herbaceous plants that date to AD 990-1160. Next comes a sandy tidal-flat deposit dated by stratigraphic position to about 1000-1500. The penultimate sheet is a tsunami deposit younger than twigs from 1410-1630. It probably represents the 1575 earthquake, whose accounts of shaking, tsunami, and landslides rival those of 1960. In that case, the record excludes the 1737 and 1837 events. The 1737 and 1837 events also appear missing in tree-ring evidence from islands of Misquihue, 30 km upriver from the sea. Here the subsidence in 1960 admitted brackish tidal water that defoliated tens of thousands of

  1. Fault failure with moderate earthquakes

    USGS Publications Warehouse

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

    1987-01-01

    High resolution strain and tilt recordings were made in the near-field of, and prior to, the May 1983 Coalinga earthquake (ML = 6.7, ?? = 51 km), the August 4, 1985, Kettleman Hills earthquake (ML = 5.5, ?? = 34 km), the April 1984 Morgan Hill earthquake (ML = 6.1, ?? = 55 km), the November 1984 Round Valley earthquake (ML = 5.8, ?? = 54 km), the January 14, 1978, Izu, Japan earthquake (ML = 7.0, ?? = 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. ?? 1987.

  2. Statistical earthquake focal mechanism forecasts

    NASA Astrophysics Data System (ADS)

    Kagan, Yan Y.; Jackson, David D.

    2014-04-01

    Forecasts of the focal mechanisms of future shallow (depth 0-70 km) earthquakes are important for seismic hazard estimates and Coulomb stress, and other models of earthquake occurrence. Here we report on a high-resolution global forecast of earthquake rate density as a function of location, magnitude and focal mechanism. In previous publications we reported forecasts of 0.5° spatial resolution, covering the latitude range from -75° to +75°, based on the Global Central Moment Tensor earthquake catalogue. In the new forecasts we have improved the spatial resolution to 0.1° and the latitude range from pole to pole. Our focal mechanism estimates require distance-weighted combinations of observed focal mechanisms within 1000 km of each gridpoint. Simultaneously, we calculate an average rotation angle between the forecasted mechanism and all the surrounding mechanisms, using the method of Kagan & Jackson proposed in 1994. This average angle reveals the level of tectonic complexity of a region and indicates the accuracy of the prediction. The procedure becomes problematical where longitude lines are not approximately parallel, and where shallow earthquakes are so sparse that an adequate sample spans very large distances. North or south of 75°, the azimuths of points 1000 km away may vary by about 35°. We solved this problem by calculating focal mechanisms on a plane tangent to the Earth's surface at each forecast point, correcting for the rotation of the longitude lines at the locations of earthquakes included in the averaging. The corrections are negligible between -30° and +30° latitude, but outside that band uncorrected rotations can be significantly off. Improved forecasts at 0.5° and 0.1° resolution are posted at http://eq.ess.ucla.edu/kagan/glob_gcmt_index.html.

  3. Izmit, Turkey 1999 Earthquake Interferogram

    NASA Image and Video Library

    2001-03-30

    This image is an interferogram that was created using pairs of images taken by Synthetic Aperture Radar (SAR). The images, acquired at two different times, have been combined to measure surface deformation or changes that may have occurred during the time between data acquisition. The images were collected by the European Space Agency's Remote Sensing satellite (ERS-2) on 13 August 1999 and 17 September 1999 and were combined to produce these image maps of the apparent surface deformation, or changes, during and after the 17 August 1999 Izmit, Turkey earthquake. This magnitude 7.6 earthquake was the largest in 60 years in Turkey and caused extensive damage and loss of life. Each of the color contours of the interferogram represents 28 mm (1.1 inches) of motion towards the satellite, or about 70 mm (2.8 inches) of horizontal motion. White areas are outside the SAR image or water of seas and lakes. The North Anatolian Fault that broke during the Izmit earthquake moved more than 2.5 meters (8.1 feet) to produce the pattern measured by the interferogram. Thin red lines show the locations of fault breaks mapped on the surface. The SAR interferogram shows that the deformation and fault slip extended west of the surface faults, underneath the Gulf of Izmit. Thick black lines mark the fault rupture inferred from the SAR data. Scientists are using the SAR interferometry along with other data collected on the ground to estimate the pattern of slip that occurred during the Izmit earthquake. This then used to improve computer models that predict how this deformation transferred stress to other faults and to the continuation of the North Anatolian Fault, which extends to the west past the large city of Istanbul. These models show that the Izmit earthquake further increased the already high probability of a major earthquake near Istanbul. http://photojournal.jpl.nasa.gov/catalog/PIA00557

  4. Izmit, Turkey 1999 Earthquake Interferogram

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This image is an interferogram that was created using pairs of images taken by Synthetic Aperture Radar (SAR). The images, acquired at two different times, have been combined to measure surface deformation or changes that may have occurred during the time between data acquisition. The images were collected by the European Space Agency's Remote Sensing satellite (ERS-2) on 13 August 1999 and 17 September 1999 and were combined to produce these image maps of the apparent surface deformation, or changes, during and after the 17 August 1999 Izmit, Turkey earthquake. This magnitude 7.6 earthquake was the largest in 60 years in Turkey and caused extensive damage and loss of life. Each of the color contours of the interferogram represents 28 mm (1.1 inches) of motion towards the satellite, or about 70 mm (2.8 inches) of horizontal motion. White areas are outside the SAR image or water of seas and lakes. The North Anatolian Fault that broke during the Izmit earthquake moved more than 2.5 meters (8.1 feet) to produce the pattern measured by the interferogram. Thin red lines show the locations of fault breaks mapped on the surface. The SAR interferogram shows that the deformation and fault slip extended west of the surface faults, underneath the Gulf of Izmit. Thick black lines mark the fault rupture inferred from the SAR data. Scientists are using the SAR interferometry along with other data collected on the ground to estimate the pattern of slip that occurred during the Izmit earthquake. This then used to improve computer models that predict how this deformation transferred stress to other faults and to the continuation of the North Anatolian Fault, which extends to the west past the large city of Istanbul. These models show that the Izmit earthquake further increased the already high probability of a major earthquake near Istanbul.

  5. Modeling, Forecasting and Mitigating Extreme Earthquakes

    NASA Astrophysics Data System (ADS)

    Ismail-Zadeh, A.; Le Mouel, J.; Soloviev, A.

    2012-12-01

    Recent earthquake disasters highlighted the importance of multi- and trans-disciplinary studies of earthquake risk. A major component of earthquake disaster risk analysis is hazards research, which should cover not only a traditional assessment of ground shaking, but also studies of geodetic, paleoseismic, geomagnetic, hydrological, deep drilling and other geophysical and geological observations together with comprehensive modeling of earthquakes and forecasting extreme events. Extreme earthquakes (large magnitude and rare events) are manifestations of complex behavior of the lithosphere structured as a hierarchical system of blocks of different sizes. Understanding of physics and dynamics of the extreme events comes from observations, measurements and modeling. A quantitative approach to simulate earthquakes in models of fault dynamics will be presented. The models reproduce basic features of the observed seismicity (e.g., the frequency-magnitude relationship, clustering of earthquakes, occurrence of extreme seismic events). They provide a link between geodynamic processes and seismicity, allow studying extreme events, influence of fault network properties on seismic patterns and seismic cycles, and assist, in a broader sense, in earthquake forecast modeling. Some aspects of predictability of large earthquakes (how well can large earthquakes be predicted today?) will be also discussed along with possibilities in mitigation of earthquake disasters (e.g., on 'inverse' forensic investigations of earthquake disasters).

  6. Earthquakes in the New Zealand Region.

    ERIC Educational Resources Information Center

    Wallace, Cleland

    1995-01-01

    Presents a thorough overview of earthquakes in New Zealand, discussing plate tectonics, seismic measurement, and historical occurrences. Includes 10 figures illustrating such aspects as earthquake distribution, intensity, and fissures in the continental crust. Tabular data includes a list of most destructive earthquakes and descriptive effects…

  7. 13 CFR 120.174 - Earthquake hazards.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 13 Business Credit and Assistance 1 2013-01-01 2013-01-01 false Earthquake hazards. 120.174... Applying to All Business Loans Requirements Imposed Under Other Laws and Orders § 120.174 Earthquake..., the construction must conform with the “National Earthquake Hazards Reduction Program (“NEHRP...

  8. 13 CFR 120.174 - Earthquake hazards.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 13 Business Credit and Assistance 1 2014-01-01 2014-01-01 false Earthquake hazards. 120.174... Applying to All Business Loans Requirements Imposed Under Other Laws and Orders § 120.174 Earthquake..., the construction must conform with the “National Earthquake Hazards Reduction Program (“NEHRP...

  9. Understanding and responding to earthquake hazards

    NASA Technical Reports Server (NTRS)

    Raymond, C. A.; Lundgren, P. R.; Madsen, S. N.; Rundle, J. B.

    2002-01-01

    Advances in understanding of the earthquake cycle and in assessing earthquake hazards is a topic of great importance. Dynamic earthquake hazard assessments resolved for a range of spatial scales and time scales will allow a more systematic approach to prioritizing the retrofitting of vulnerable structures, relocating populations at risk, protecting lifelines, preparing for disasters, and educating the public.

  10. 13 CFR 120.174 - Earthquake hazards.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 13 Business Credit and Assistance 1 2012-01-01 2012-01-01 false Earthquake hazards. 120.174... Applying to All Business Loans Requirements Imposed Under Other Laws and Orders § 120.174 Earthquake..., the construction must conform with the “National Earthquake Hazards Reduction Program (“NEHRP...

  11. 13 CFR 120.174 - Earthquake hazards.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 13 Business Credit and Assistance 1 2011-01-01 2011-01-01 false Earthquake hazards. 120.174... Applying to All Business Loans Requirements Imposed Under Other Laws and Orders § 120.174 Earthquake..., the construction must conform with the “National Earthquake Hazards Reduction Program (“NEHRP...

  12. Earth science: lasting earthquake legacy

    USGS Publications Warehouse

    Parsons, Thomas E.

    2009-01-01

    On 31 August 1886, a magnitude-7 shock struck Charleston, South Carolina; low-level activity continues there today. One view of seismic hazard is that large earthquakes will return to New Madrid and Charleston at intervals of about 500 years. With expected ground motions that would be stronger than average, that prospect produces estimates of earthquake hazard that rival those at the plate boundaries marked by the San Andreas fault and Cascadia subduction zone. The result is two large 'bull's-eyes' on the US National Seismic Hazard Maps — which, for example, influence regional building codes and perceptions of public safety.

  13. Earthquakes triggered by fluid extraction

    USGS Publications Warehouse

    Segall, P.

    1989-01-01

    Seismicity is correlated in space and time with production from some oil and gas fields where pore pressures have declined by several tens of megapascals. Reverse faulting has occurred both above and below petroleum reservoirs, and normal faulting has occurred on the flanks of at least one reservoir. The theory of poroelasticity requires that fluid extraction locally alter the state of stress. Calculations with simple geometries predict stress perturbations that are consistent with observed earthquake locations and focal mechanisms. Measurements of surface displacement and strain, pore pressure, stress, and poroelastic rock properties in such areas could be used to test theoretical predictions and improve our understanding of earthquake mechanics. -Author

  14. Earthquake location in island arcs

    USGS Publications Warehouse

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

    1982-01-01

    A comprehensive data set of selected teleseismic P-wave arrivals and local-network P- and S-wave arrivals from large earthquakes occurring at all depths within a small section of the central Aleutians is used to examine the general problem of earthquake location in island arcs. Reference hypocenters for this special data set are determined for shallow earthquakes from local-network data and for deep earthquakes from combined local and teleseismic data by joint inversion for structure and location. The high-velocity lithospheric slab beneath the central Aleutians may displace hypocenters that are located using spherically symmetric Earth models; the amount of displacement depends on the position of the earthquakes with respect to the slab and on whether local or teleseismic data are used to locate the earthquakes. Hypocenters for trench and intermediate-depth events appear to be minimally biased by the effects of slab structure on rays to teleseismic stations. However, locations of intermediate-depth events based on only local data are systematically displaced southwards, the magnitude of the displacement being proportional to depth. Shallow-focus events along the main thrust zone, although well located using only local-network data, are severely shifted northwards and deeper, with displacements as large as 50 km, by slab effects on teleseismic travel times. Hypocenters determined by a method that utilizes seismic ray tracing through a three-dimensional velocity model of the subduction zone, derived by thermal modeling, are compared to results obtained by the method of joint hypocenter determination (JHD) that formally assumes a laterally homogeneous velocity model over the source region and treats all raypath anomalies as constant station corrections to the travel-time curve. The ray-tracing method has the theoretical advantage that it accounts for variations in travel-time anomalies within a group of events distributed over a sizable region of a dipping, high

  15. Earthquake Education in Prime Time

    NASA Astrophysics Data System (ADS)

    de Groot, R.; Abbott, P.; Benthien, M.

    2004-12-01

    Since 2001, the Southern California Earthquake Center (SCEC) has collaborated on several video production projects that feature important topics related to earthquake science, engineering, and preparedness. These projects have also fostered many fruitful and sustained partnerships with a variety of organizations that have a stake in hazard education and preparedness. The Seismic Sleuths educational video first appeared in the spring season 2001 on Discovery Channel's Assignment Discovery. Seismic Sleuths is based on a highly successful curriculum package developed jointly by the American Geophysical Union and The Department of Homeland Security Federal Emergency Management Agency. The California Earthquake Authority (CEA) and the Institute for Business and Home Safety supported the video project. Summer Productions, a company with a reputation for quality science programming, produced the Seismic Sleuths program in close partnership with scientists, engineers, and preparedness experts. The program has aired on the National Geographic Channel as recently as Fall 2004. Currently, SCEC is collaborating with Pat Abbott, a geology professor at San Diego State University (SDSU) on the video project Written In Stone: Earthquake Country - Los Angeles. Partners on this project include the California Seismic Safety Commission, SDSU, SCEC, CEA, and the Insurance Information Network of California. This video incorporates live-action demonstrations, vivid animations, and a compelling host (Abbott) to tell the story about earthquakes in the Los Angeles region. The Written in Stone team has also developed a comprehensive educator package that includes the video, maps, lesson plans, and other supporting materials. We will present the process that facilitates the creation of visually effective, factually accurate, and entertaining video programs. We acknowledge the need to have a broad understanding of the literature related to communication, media studies, science education, and

  16. Utah FORGE Site Earthquake Animation

    SciTech Connect

    Joe Moore

    This is a .kml earthquake animation covering the period of 1991 - 2011 for the Utah Milford FORGE site. It displays seismic events using different sized bubbles according to magnitude. It covers the general Utah FORGE area (large shaded rectangle) with the final site displayed as a smaller polygon along the northwestern margin. Earthquakes are subdivide into clusters and the time, date, and magnitude of each event is included. Nearby seismic stations are symbolized with triangles. This was created by the University of Utah Seismograph Stations (UUSS).

  17. Source Mechanisms of Destructive Tsunamigenic Earthquakes occurred along the Major Subduction Zones

    NASA Astrophysics Data System (ADS)

    Yolsal-Çevikbilen, Seda; Taymaz, Tuncay; Ulutaş, Ergin

    2016-04-01

    Subduction zones, where an oceanic plate is subducted down into the mantle by tectonic forces, are potential tsunami locations. Many big, destructive and tsunamigenic earthquakes (Mw > 7.5) and high amplitude tsunami waves are observed along the major subduction zones particularly near Indonesia, Japan, Kuril and Aleutan Islands, Gulf of Alaska, Southern America. Not all earthquakes are tsunamigenic; in order to generate a tsunami, the earthquake must occur under or near the ocean, be large, and create significant vertical movements of the seafloor. It is also known that tsunamigenic earthquakes release their energy over a couple of minutes, have long source time functions and slow-smooth ruptures. In this study, we performed point-source inversions by using teleseismic long-period P- and SH- and broad-band P-waveforms recorded by the Federation of Digital Seismograph Networks (FDSN) and the Global Digital Seismograph Network (GDSN) stations. We obtained source mechanism parameters and finite-fault slip distributions of recent destructive ten earthquakes (Mw ≥ 7.5) by comparing the shapes and amplitudes of long period P- and SH-waveforms, recorded in the distance range of 30° - 90°, with synthetic waveforms. We further obtained finite-fault rupture histories of those earthquakes to determine the faulting area (fault length and width), maximum displacement, rupture duration and stress drop. We applied a new back-projection method that uses teleseismic P-waveforms to integrate the direct P-phase with reflected phases from structural discontinuities near the source, and customized it to estimate the spatio-temporal distribution of the seismic energy release of earthquakes. Inversion results exhibit that recent tsunamigenic earthquakes show dominantly thrust faulting mechanisms with small amount of strike-slip components. Their focal depths are also relatively shallow (h < 40 km). As an example, the September 16, 2015 Illapel (Chile) earthquake (Mw: 8.3; h: 26 km

  18. 4 Earthquake: Major offshore earthquakes recall the Aztec myth

    USGS Publications Warehouse

    ,

    1970-01-01

    Long before the sun clears the eastern mountains of April 29, 1970, the savanna highlands of Chiapas tremble from a magnitude 6.7 earthquake centered off the Pacific coast near Mexico’s southern border. Then, for a few hours, he Isthmus of Tehuantepec is quiet.

  19. Dancing Earthquake Science Assists Recovery from the Christchurch Earthquakes

    ERIC Educational Resources Information Center

    Egan, Candice J.; Quigley, Mark C.

    2015-01-01

    The 2010-2012 Christchurch (Canterbury) earthquakes in New Zealand caused loss of life and psychological distress in residents throughout the region. In 2011, student dancers of the Hagley Dance Company and dance professionals choreographed the performance "Move: A Seismic Journey" for the Christchurch Body Festival that explored…

  20. A Method for Estimation of Death Tolls in Disastrous Earthquake

    NASA Astrophysics Data System (ADS)

    Pai, C.; Tien, Y.; Teng, T.

    2004-12-01

    Fatality tolls caused by the disastrous earthquake are the one of the most important items among the earthquake damage and losses. If we can precisely estimate the potential tolls and distribution of fatality in individual districts as soon as the earthquake occurrences, it not only make emergency programs and disaster management more effective but also supply critical information to plan and manage the disaster and the allotments of disaster rescue manpower and medicine resources in a timely manner. In this study, we intend to reach the estimation of death tolls caused by the Chi-Chi earthquake in individual districts based on the Attributive Database of Victims, population data, digital maps and Geographic Information Systems. In general, there were involved many factors including the characteristics of ground motions, geological conditions, types and usage habits of buildings, distribution of population and social-economic situations etc., all are related to the damage and losses induced by the disastrous earthquake. The density of seismic stations in Taiwan is the greatest in the world at present. In the meantime, it is easy to get complete seismic data by earthquake rapid-reporting systems from the Central Weather Bureau: mostly within about a minute or less after the earthquake happened. Therefore, it becomes possible to estimate death tolls caused by the earthquake in Taiwan based on the preliminary information. Firstly, we form the arithmetic mean of the three components of the Peak Ground Acceleration (PGA) to give the PGA Index for each individual seismic station, according to the mainshock data of the Chi-Chi earthquake. To supply the distribution of Iso-seismic Intensity Contours in any districts and resolve the problems for which there are no seismic station within partial districts through the PGA Index and geographical coordinates in individual seismic station, the Kriging Interpolation Method and the GIS software, The population density depends on

  1. Testing hypotheses of earthquake occurrence

    NASA Astrophysics Data System (ADS)

    Kagan, Y. Y.; Jackson, D. D.; Schorlemmer, D.; Gerstenberger, M.

    2003-12-01

    We present a relatively straightforward likelihood method for testing those earthquake hypotheses that can be stated as vectors of earthquake rate density in defined bins of area, magnitude, and time. We illustrate the method as it will be applied to the Regional Earthquake Likelihood Models (RELM) project of the Southern California Earthquake Center (SCEC). Several earthquake forecast models are being developed as part of this project, and additional contributed forecasts are welcome. Various models are based on fault geometry and slip rates, seismicity, geodetic strain, and stress interactions. We would test models in pairs, requiring that both forecasts in a pair be defined over the same set of bins. Thus we offer a standard "menu" of bins and ground rules to encourage standardization. One menu category includes five-year forecasts of magnitude 5.0 and larger. Forecasts would be in the form of a vector of yearly earthquake rates on a 0.05 degree grid at the beginning of the test. Focal mechanism forecasts, when available, would be also be archived and used in the tests. The five-year forecast category may be appropriate for testing hypotheses of stress shadows from large earthquakes. Interim progress will be evaluated yearly, but final conclusions would be made on the basis of cumulative five-year performance. The second category includes forecasts of earthquakes above magnitude 4.0 on a 0.05 degree grid, evaluated and renewed daily. Final evaluation would be based on cumulative performance over five years. Other types of forecasts with different magnitude, space, and time sampling are welcome and will be tested against other models with shared characteristics. All earthquakes would be counted, and no attempt made to separate foreshocks, main shocks, and aftershocks. Earthquakes would be considered as point sources located at the hypocenter. For each pair of forecasts, we plan to compute alpha, the probability that the first would be wrongly rejected in favor of

  2. Digital Radiography

    NASA Technical Reports Server (NTRS)

    1986-01-01

    System One, a digital radiography system, incorporates a reusable image medium (RIM) which retains an image. No film is needed; the RIM is read with a laser scanner, and the information is used to produce a digital image on an image processor. The image is stored on an optical disc. System allows the radiologist to "dial away" unwanted images to compare views on three screens. It is compatible with existing equipment and cost efficient. It was commercialized by a Stanford researcher from energy selective technology developed under a NASA grant.

  3. Earthquake Fingerprints: Representing Earthquake Waveforms for Similarity-Based Detection

    NASA Astrophysics Data System (ADS)

    Bergen, K.; Beroza, G. C.

    2016-12-01

    New earthquake detection methods, such as Fingerprint and Similarity Thresholding (FAST), use fast approximate similarity search to identify similar waveforms in long-duration data without templates (Yoon et al. 2015). These methods have two key components: fingerprint extraction and an efficient search algorithm. Fingerprint extraction converts waveforms into fingerprints, compact signatures that represent short-duration waveforms for identification and search. Earthquakes are detected using an efficient indexing and search scheme, such as locality-sensitive hashing, that identifies similar waveforms in a fingerprint database. The quality of the search results, and thus the earthquake detection results, is strongly dependent on the fingerprinting scheme. Fingerprint extraction should map similar earthquake waveforms to similar waveform fingerprints to ensure a high detection rate, even under additive noise and small distortions. Additionally, fingerprints corresponding to noise intervals should have mutually dissimilar fingerprints to minimize false detections. In this work, we compare the performance of multiple fingerprint extraction approaches for the earthquake waveform similarity search problem. We apply existing audio fingerprinting (used in content-based audio identification systems) and time series indexing techniques and present modified versions that are specifically adapted for seismic data. We also explore data-driven fingerprinting approaches that can take advantage of labeled or unlabeled waveform data. For each fingerprinting approach we measure its ability to identify similar waveforms in a low signal-to-noise setting, and quantify the trade-off between true and false detection rates in the presence of persistent noise sources. We compare the performance using known event waveforms from eight independent stations in the Northern California Seismic Network.

  4. Earthquake Warning Performance in Vallejo for the South Napa Earthquake

    NASA Astrophysics Data System (ADS)

    Wurman, G.; Price, M.

    2014-12-01

    In 2002 and 2003, Seismic Warning Systems, Inc. installed first-generation QuakeGuardTM earthquake warning devices at all eight fire stations in Vallejo, CA. These devices are designed to detect the P-wave of an earthquake and initiate predetermined protective actions if the impending shaking is estimated at approximately Modifed Mercalli Intensity V or greater. At the Vallejo fire stations the devices were set up to sound an audio alert over the public address system and to command the equipment bay doors to open. In August 2014, after more than 11 years of operating in the fire stations with no false alarms, the five units that were still in use triggered correctly on the MW 6.0 South Napa earthquake, less than 16 km away. The audio alert sounded in all five stations, providing fire fighters with 1.5 to 2.5 seconds of warning before the arrival of the S-wave, and the equipment bay doors opened in three of the stations. In one station the doors were disconnected from the QuakeGuard device, and another station lost power before the doors opened completely. These problems highlight just a small portion of the complexity associated with realizing actionable earthquake warnings. The issues experienced in this earthquake have already been addressed in subsequent QuakeGuard product generations, with downstream connection monitoring and backup power for critical systems. The fact that the fire fighters in Vallejo were afforded even two seconds of warning at these epicentral distances results from the design of the QuakeGuard devices, which focuses on rapid false positive rejection and ground motion estimates. We discuss the performance of the ground motion estimation algorithms, with an emphasis on the accuracy and timeliness of the estimates at close epicentral distances.

  5. Intrastab Earthquakes: Dehydration of the Cascadia Slab

    USGS Publications Warehouse

    Preston, L.A.; Creager, K.C.; Crosson, R.S.; Brocher, T.M.; Trehu, A.M.

    2003-01-01

    We simultaneously invert travel times of refracted and wide-angle reflected waves for three-dimensional compressional-wave velocity structure, earthquake locations, and reflector geometry in northwest Washington state. The reflector, interpreted to be the crust-mantle boundary (Moho) of the subducting Juan de Fuca plate, separates intrastab earthquakes into two groups, permitting a new understanding of the origins of intrastab earthquakes in Cascadia. Earthquakes up-dip of the Moho's 45-kilometer depth contour occur below the reflector, in the subducted oceanic mantle, consistent with serpentinite dehydration; earthquakes located down-dip occur primarily within the subducted crust, consistent with the basalt-to-eclogite transformation.

  6. Earthquake predictions using seismic velocity ratios

    USGS Publications Warehouse

    Sherburne, R. W.

    1979-01-01

    Since the beginning of modern seismology, seismologists have contemplated predicting earthquakes. The usefulness of earthquake predictions to the reduction of human and economic losses and the value of long-range earthquake prediction to planning is obvious. Not as clear are the long-range economic and social impacts of earthquake prediction to a speicifc area. The general consensus of opinion among scientists and government officials, however, is that the quest of earthquake prediction is a worthwhile goal and should be prusued with a sense of urgency. 

  7. Earthquakes-Rattling the Earth's Plumbing System

    USGS Publications Warehouse

    Sneed, Michelle; Galloway, Devin L.; Cunningham, William L.

    2003-01-01

    Hydrogeologic responses to earthquakes have been known for decades, and have occurred both close to, and thousands of miles from earthquake epicenters. Water wells have become turbid, dry or begun flowing, discharge of springs and ground water to streams has increased and new springs have formed, and well and surface-water quality have become degraded as a result of earthquakes. Earthquakes affect our Earth’s intricate plumbing system—whether you live near the notoriously active San Andreas Fault in California, or far from active faults in Florida, an earthquake near or far can affect you and the water resources you depend on.

  8. Measuring the size of an earthquake

    USGS Publications Warehouse

    Spence, W.

    1977-01-01

    Earthquakes occur in a broad range of sizes. A rock burst in an Idaho silver mine may involve the fracture of 1 meter of rock; the 1965 Rat island earthquake in the Aleutian arc involved a 650-kilometer lenght of Earth's crust. Earthquakes can be even smaller and even larger. if an earthquake is felt or causes perceptible surface damage, then its intesnity of shaking can be subjectively estimated. But many large earthquakes occur in oceanic area or at great focal depths. These are either simply not felt or their felt pattern does not really indicate their true size. 

  9. Pre-earthquake magnetic pulses

    NASA Astrophysics Data System (ADS)

    Scoville, J.; Heraud, J.; Freund, F.

    2015-08-01

    A semiconductor model of rocks is shown to describe unipolar magnetic pulses, a phenomenon that has been observed prior to earthquakes. These pulses are suspected to be generated deep in the Earth's crust, in and around the hypocentral volume, days or even weeks before earthquakes. Their extremely long wavelength allows them to pass through kilometers of rock. Interestingly, when the sources of these pulses are triangulated, the locations coincide with the epicenters of future earthquakes. We couple a drift-diffusion semiconductor model to a magnetic field in order to describe the electromagnetic effects associated with electrical currents flowing within rocks. The resulting system of equations is solved numerically and it is seen that a volume of rock may act as a diode that produces transient currents when it switches bias. These unidirectional currents are expected to produce transient unipolar magnetic pulses similar in form, amplitude, and duration to those observed before earthquakes, and this suggests that the pulses could be the result of geophysical semiconductor processes.

  10. Bam, Iran, Radar Interferometry -- Earthquake

    NASA Image and Video Library

    2004-06-25

    A magnitude 6.5 earthquake devastated the small city of Bam in southeast Iran on December 26, 2003. The two images from ESA Envisat show similar measures of the radar interferometric correlation in grayscale on the left and in false colors on the right.

  11. Detecting Earthquakes--Part 2.

    ERIC Educational Resources Information Center

    Isenberg, C.; And Others

    1983-01-01

    Basic concepts associated with seismic wave propagation through the earth and the location of seismic events were explained in part 1 (appeared in January 1983 issue). This part focuses on the construction of a student seismometer for detecting earthquakes and underground nuclear explosions anywhere on the earth's surface. (Author/JN)

  12. Earthquakes May-June 1980.

    USGS Publications Warehouse

    Person, W.J.

    1981-01-01

    The months were seismically active, although only one major event (7.0-7.9) occurred in an unpopulated Philippine Island. Mexico was struck by a 6.3 quake on June 9 killing at least two people. The most significant earthquake in the United States was in the Mammoth Lakes area of California. -from Author

  13. Using Smartphones to Detect Earthquakes

    NASA Astrophysics Data System (ADS)

    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.

  14. Hypothesis testing and earthquake prediction.

    PubMed

    Jackson, D D

    1996-04-30

    Requirements for testing include advance specification of the conditional rate density (probability per unit time, area, and magnitude) or, alternatively, probabilities for specified intervals of time, space, and magnitude. Here I consider testing fully specified hypotheses, with no parameter adjustments or arbitrary decisions allowed during the test period. Because it may take decades to validate prediction methods, it is worthwhile to formulate testable hypotheses carefully in advance. Earthquake prediction generally implies that the probability will be temporarily higher than normal. Such a statement requires knowledge of "normal behavior"--that is, it requires a null hypothesis. Hypotheses can be tested in three ways: (i) by comparing the number of actual earth-quakes to the number predicted, (ii) by comparing the likelihood score of actual earthquakes to the predicted distribution, and (iii) by comparing the likelihood ratio to that of a null hypothesis. The first two tests are purely self-consistency tests, while the third is a direct comparison of two hypotheses. Predictions made without a statement of probability are very difficult to test, and any test must be based on the ratio of earthquakes in and out of the forecast regions.

  15. Hypothesis testing and earthquake prediction.

    PubMed Central

    Jackson, D D

    1996-01-01

    Requirements for testing include advance specification of the conditional rate density (probability per unit time, area, and magnitude) or, alternatively, probabilities for specified intervals of time, space, and magnitude. Here I consider testing fully specified hypotheses, with no parameter adjustments or arbitrary decisions allowed during the test period. Because it may take decades to validate prediction methods, it is worthwhile to formulate testable hypotheses carefully in advance. Earthquake prediction generally implies that the probability will be temporarily higher than normal. Such a statement requires knowledge of "normal behavior"--that is, it requires a null hypothesis. Hypotheses can be tested in three ways: (i) by comparing the number of actual earth-quakes to the number predicted, (ii) by comparing the likelihood score of actual earthquakes to the predicted distribution, and (iii) by comparing the likelihood ratio to that of a null hypothesis. The first two tests are purely self-consistency tests, while the third is a direct comparison of two hypotheses. Predictions made without a statement of probability are very difficult to test, and any test must be based on the ratio of earthquakes in and out of the forecast regions. PMID:11607663

  16. Digital Storytelling

    ERIC Educational Resources Information Center

    Iacchia, Flora

    2005-01-01

    Today, schools are actively looking for new ways to enable their students to develop storytelling skills. These skills should empower children and young adults to practice collaborative learning on many levels, from reading and writing to painting and project management. In this framework, digital painting provides educators with innovative…

  17. Digital Forensics

    ERIC Educational Resources Information Center

    Harron, Jason; Langdon, John; Gonzalez, Jennifer; Cater, Scott

    2017-01-01

    The term forensic science may evoke thoughts of blood-spatter analysis, DNA testing, and identifying molds, spores, and larvae. A growing part of this field, however, is that of digital forensics, involving techniques with clear connections to math and physics. This article describes a five-part project involving smartphones and the investigation…

  18. Digital Tidbits

    ERIC Educational Resources Information Center

    Kumaran, Maha; Geary, Joe

    2011-01-01

    Technology has transformed libraries. There are digital libraries, electronic collections, online databases and catalogs, ebooks, downloadable books, and much more. With free technology such as social websites, newspaper collections, downloadable online calendars, clocks and sticky notes, online scheduling, online document sharing, and online…

  19. Digital books.

    PubMed

    Wink, Diane M

    2011-01-01

    In this bimonthly series, the author examines how nurse educators can use the Internet and Web-based computer technologies such as search, communication, and collaborative writing tools; social networking and social bookmarking sites; virtual worlds; and Web-based teaching and learning programs. This article describes digital books.

  20. Digital Badges

    ERIC Educational Resources Information Center

    Frederiksen, Linda

    2013-01-01

    Unlike so much of the current vocabulary in education and technology that seems to stir more confusion than clarity, most public service librarians may already have a general idea about digital badges. As visual representations of individual accomplishments, competencies or skills that are awarded by groups, institutions, or organizations, they…

  1. Earthquake precursors: activation or quiescence?

    NASA Astrophysics Data System (ADS)

    Rundle, John B.; Holliday, James R.; Yoder, Mark; Sachs, Michael K.; Donnellan, Andrea; Turcotte, Donald L.; Tiampo, Kristy F.; Klein, William; Kellogg, Louise H.

    2011-10-01

    We discuss the long-standing question of whether the probability for large earthquake occurrence (magnitudes m > 6.0) is highest during time periods of smaller event activation, or highest during time periods of smaller event quiescence. The physics of the activation model are based on an idea from the theory of nucleation, that a small magnitude earthquake has a finite probability of growing into a large earthquake. The physics of the quiescence model is based on the idea that the occurrence of smaller earthquakes (here considered as magnitudes m > 3.5) may be due to a mechanism such as critical slowing down, in which fluctuations in systems with long-range interactions tend to be suppressed prior to large nucleation events. To illuminate this question, we construct two end-member forecast models illustrating, respectively, activation and quiescence. The activation model assumes only that activation can occur, either via aftershock nucleation or triggering, but expresses no choice as to which mechanism is preferred. Both of these models are in fact a means of filtering the seismicity time-series to compute probabilities. Using 25 yr of data from the California-Nevada catalogue of earthquakes, we show that of the two models, activation and quiescence, the latter appears to be the better model, as judged by backtesting (by a slight but not significant margin). We then examine simulation data from a topologically realistic earthquake model for California seismicity, Virtual California. This model includes not only earthquakes produced from increases in stress on the fault system, but also background and off-fault seismicity produced by a BASS-ETAS driving mechanism. Applying the activation and quiescence forecast models to the simulated data, we come to the opposite conclusion. Here, the activation forecast model is preferred to the quiescence model, presumably due to the fact that the BASS component of the model is essentially a model for activated seismicity. These

  2. Predecessors of the giant 1960 Chile earthquake

    USGS Publications Warehouse

    Cisternas, M.; Atwater, B.F.; Torrejon, F.; Sawai, Y.; Machuca, G.; Lagos, M.; Eipert, A.; Youlton, C.; Salgado, I.; Kamataki, T.; Shishikura, M.; Rajendran, C.P.; Malik, J.K.; Rizal, Y.; Husni, M.

    2005-01-01

    It is commonly thought that the longer the time since last earthquake, the larger the next earthquake's slip will be. But this logical predictor of earthquake size, unsuccessful for large earthquakes on a strike-slip fault, fails also with the giant 1960 Chile earthquake of magnitude 9.5 (ref. 3). Although the time since the preceding earthquake spanned 123 years (refs 4, 5), the estimated slip in 1960, which occurred on a fault between the Nazca and South American tectonic plates, equalled 250-350 years' worth of the plate motion. Thus the average interval between such giant earthquakes on this fault should span several centuries. Here we present evidence that such long intervals were indeed typical of the last two millennia. We use buried soils and sand layers as records of tectonic subsidence and tsunami inundation at an estuary midway along the 1960 rupture. In these records, the 1960 earthquake ended a recurrence interval that had begun almost four centuries before, with an earthquake documented by Spanish conquistadors in 1575. Two later earthquakes, in 1737 and 1837, produced little if any subsidence or tsunami at the estuary and they therefore probably left the fault partly loaded with accumulated plate motion that the 1960 earthquake then expended. ?? 2005 Nature Publishing Group.

  3. Predecessors of the giant 1960 Chile earthquake.

    PubMed

    Cisternas, Marco; Atwater, Brian F; Torrejón, Fernando; Sawai, Yuki; Machuca, Gonzalo; Lagos, Marcelo; Eipert, Annaliese; Youlton, Cristián; Salgado, Ignacio; Kamataki, Takanobu; Shishikura, Masanobu; Rajendran, C P; Malik, Javed K; Rizal, Yan; Husni, Muhammad

    2005-09-15

    It is commonly thought that the longer the time since last earthquake, the larger the next earthquake's slip will be. But this logical predictor of earthquake size, unsuccessful for large earthquakes on a strike-slip fault, fails also with the giant 1960 Chile earthquake of magnitude 9.5 (ref. 3). Although the time since the preceding earthquake spanned 123 years (refs 4, 5), the estimated slip in 1960, which occurred on a fault between the Nazca and South American tectonic plates, equalled 250-350 years' worth of the plate motion. Thus the average interval between such giant earthquakes on this fault should span several centuries. Here we present evidence that such long intervals were indeed typical of the last two millennia. We use buried soils and sand layers as records of tectonic subsidence and tsunami inundation at an estuary midway along the 1960 rupture. In these records, the 1960 earthquake ended a recurrence interval that had begun almost four centuries before, with an earthquake documented by Spanish conquistadors in 1575. Two later earthquakes, in 1737 and 1837, produced little if any subsidence or tsunami at the estuary and they therefore probably left the fault partly loaded with accumulated plate motion that the 1960 earthquake then expended.

  4. A note on evaluating VAN earthquake predictions

    NASA Astrophysics Data System (ADS)

    Tselentis, G.-Akis; Melis, Nicos S.

    The evaluation of the success level of an earthquake prediction method should not be based on approaches that apply generalized strict statistical laws and avoid the specific nature of the earthquake phenomenon. Fault rupture processes cannot be compared to gambling processes. The outcome of the present note is that even an ideal earthquake prediction method is still shown to be a matter of a “chancy” association between precursors and earthquakes if we apply the same procedure proposed by Mulargia and Gasperini [1992] in evaluating VAN earthquake predictions. Each individual VAN prediction has to be evaluated separately, taking always into account the specific circumstances and information available. The success level of epicenter prediction should depend on the earthquake magnitude, and magnitude and time predictions may depend on earthquake clustering and the tectonic regime respectively.

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

    NASA Astrophysics Data System (ADS)

    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

  6. Landslides triggered by the 1994 Northridge, California, earthquake

    USGS Publications Warehouse

    Harp, E.L.; Jibson, R.W.

    1996-01-01

    The 17 January 1994 Northridge, California, earthquake (Mw, = 6.7) triggered more than 11,000 landslides over an area of about 10,000 km2. Most of the landslides were concentrated in a 1000-km2 area that included the Santa Susana Mountains and the mountains north of the Santa Clara River valley. We mapped landslides triggered by the earthquake in the field and from 1:60,000-nominal-scale aerial photography provided by the U.S. Air Force and taken the morning of the earthquake; these mapped landslides were subsequently digitized and plotted in a GIS-based format. Most of the triggered landslides were shallow (1- to 5-m thick), highly disrupted falls and slides within weakly cemented Tertiary to Pleistocene clastic sediment. Average volumes of these types of landslides were less than 1000 m3, but many had volumes exceeding 100,000 m3. The larger disrupted slides commonly had runout paths of more than 50 m, and a few traveled as far as 200 m from the bases of steep parent slopes. Deeper (>5-m thick) rotational slumps and block slides numbered in the tens to perhaps hundreds, a few of which exceeded 100,000 m3 in volume. Most of these were reactivations of previously existing landslides. The largest single landslide triggered by the earthquake was a rotational slump/block slide having a volume of 8 ?? 106 m3. Analysis of the mapped landslide distribution with respect to variations in (1) landslide susceptibility and (2) strong shaking recorded by hundreds of instruments will form the basis of a seismic landslide hazard analysis of the Los Angeles area.

  7. Earthquake sources near Uturuncu Volcano

    NASA Astrophysics Data System (ADS)

    Keyson, L.; West, M. E.

    2013-12-01

    Uturuncu, located in southern Bolivia near the Chile and Argentina border, is a dacitic volcano that was last active 270 ka. It is a part of the Altiplano-Puna Volcanic Complex, which spans 50,000 km2 and is comprised of a series of ignimbrite flare-ups since ~23 ma. Two sets of evidence suggest that the region is underlain by a significant magma body. First, seismic velocities show a low velocity layer consistent with a magmatic sill below depths of 15-20 km. This inference is corroborated by high electrical conductivity between 10km and 30km. This magma body, the so called Altiplano-Puna Magma Body (APMB) is the likely source of volcanic activity in the region. InSAR studies show that during the 1990s, the volcano experienced an average uplift of about 1 to 2 cm per year. The deformation is consistent with an expanding source at depth. Though the Uturuncu region exhibits high rates of crustal seismicity, any connection between the inflation and the seismicity is unclear. We investigate the root causes of these earthquakes using a temporary network of 33 seismic stations - part of the PLUTONS project. Our primary approach is based on hypocenter locations and magnitudes paired with correlation-based relative relocation techniques. We find a strong tendency toward earthquake swarms that cluster in space and time. These swarms often last a few days and consist of numerous earthquakes with similar source mechanisms. Most seismicity occurs in the top 10 kilometers of the crust and is characterized by well-defined phase arrivals and significant high frequency content. The frequency-magnitude relationship of this seismicity demonstrates b-values consistent with tectonic sources. There is a strong clustering of earthquakes around the Uturuncu edifice. Earthquakes elsewhere in the region align in bands striking northwest-southeast consistent with regional stresses.

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

    NASA Astrophysics Data System (ADS)

    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

  9. Detection of collapsed buildings from lidar data due to the 2016 Kumamoto earthquake in Japan

    NASA Astrophysics Data System (ADS)

    Moya, Luis; Yamazaki, Fumio; Liu, Wen; Yamada, Masumi

    2018-01-01

    The 2016 Kumamoto earthquake sequence was triggered by an Mw 6.2 event at 21:26 on 14 April. Approximately 28 h later, at 01:25 on 16 April, an Mw 7.0 event (the mainshock) followed. The epicenters of both events were located near the residential area of Mashiki and affected the region nearby. Due to very strong seismic ground motion, the earthquake produced extensive damage to buildings and infrastructure. In this paper, collapsed buildings were detected using a pair of digital surface models (DSMs), taken before and after the 16 April mainshock by airborne light detection and ranging (lidar) flights. Different methods were evaluated to identify collapsed buildings from the DSMs. The change in average elevation within a building footprint was found to be the most important factor. Finally, the distribution of collapsed buildings in the study area was presented, and the result was consistent with that of a building damage survey performed after the earthquake.

  10. ARMA models for earthquake ground motions. Seismic safety margins research program

    SciTech Connect

    Chang, M. K.; Kwiatkowski, J. W.; Nau, R. F.

    1981-02-01

    Four major California earthquake records were analyzed by use of a class of discrete linear time-domain processes commonly referred to as ARMA (Autoregressive/Moving-Average) models. It was possible to analyze these different earthquakes, identify the order of the appropriate ARMA model(s), estimate parameters, and test the residuals generated by these models. It was also possible to show the connections, similarities, and differences between the traditional continuous models (with parameter estimates based on spectral analyses) and the discrete models with parameters estimated by various maximum-likelihood techniques applied to digitized acceleration data in the time domain. The methodology proposed is suitable for simulatingmore » earthquake ground motions in the time domain, and appears to be easily adapted to serve as inputs for nonlinear discrete time models of structural motions. 60 references, 19 figures, 9 tables.« less

  11. Evidence of the 1762 Arakan and Prior Earthquakes in the Northern Sunda Subduction

    NASA Astrophysics Data System (ADS)

    Mondal, Dhiman Ranjan

    The objective of this dissertation is to understand the seismic hazard associated with Arakan segment of the northern Sunda subduction along SE Bangladesh. In order to do that, it is necessary to document geologic evidence for the 1762 Arakan earthquake and prior events, to help estimate the recurrence interval (repeat time) for that earthquake. Historical records described that the 1762 earthquake caused extensive damage along the Arakan segment of the Sunda subduction system. But the geologic evidence for the earthquake farther north is necessary to better understand its associated seismic hazard to the densely populated nation of Bangladesh. This dissertation presents the results obtained from U/Th dating of the dead and live coral microatolls including their elevations measured by high precision GPS from the Saint Martin's Island, DEM analysis and elevation of terraces from Teknaf coast and fault dislocation modeling based on the data obtained from the Saint Martin's Island and Teknaf. Coral microatolls from Saint Martin's island documents the evidence of the 1762 and prior earthquakes. The U/Th ages documents strong evidence of microatoll die offs related to the 1762 earthquake. The > 2 m elevation difference between the dead microatolls and present-day living corals suggest that the microatolls died due to the coseismic uplift of 1762 Arakan earthquake. This dissertation also provides evidence for two additional earthquakes taking place in 700 and 1140 C.E. which suggests an earthquake recurrence interval of 500 years. Geomorphic studies documented three terraces along the coast of Teknaf. Several marine terraces have been previously documented along the west coast of Myanmar. The youngest of these terraces has been correlated to the coseismic uplift of 1762 Arakan along the Myanmar coast. The terraces along the coast of Teknaf are characterized by flat to semi-flat surfaces followed by sharp topographic rises. DEM (Digital Elevation System) analysis and GPS

  12. PAGER-CAT: A composite earthquake catalog for calibrating global fatality models

    USGS Publications Warehouse

    Allen, T.I.; Marano, K.D.; Earle, P.S.; Wald, D.J.

    2009-01-01

    We have described the compilation and contents of PAGER-CAT, an earthquake catalog developed principally for calibrating earthquake fatality models. It brings together information from a range of sources in a comprehensive, easy to use digital format. Earthquake source information (e.g., origin time, hypocenter, and magnitude) contained in PAGER-CAT has been used to develop an Atlas of Shake Maps of historical earthquakes (Allen et al. 2008) that can subsequently be used to estimate the population exposed to various levels of ground shaking (Wald et al. 2008). These measures will ultimately yield improved earthquake loss models employing the uniform hazard mapping methods of ShakeMap. Currently PAGER-CAT does not consistently contain indicators of landslide and liquefaction occurrence prior to 1973. In future PAGER-CAT releases we plan to better document the incidence of these secondary hazards. This information is contained in some existing global catalogs but is far from complete and often difficult to parse. Landslide and liquefaction hazards can be important factors contributing to earthquake losses (e.g., Marano et al. unpublished). Consequently, the absence of secondary hazard indicators in PAGER-CAT, particularly for events prior to 1973, could be misleading to sorne users concerned with ground-shaking-related losses. We have applied our best judgment in the selection of PAGER-CAT's preferred source parameters and earthquake effects. We acknowledge the creation of a composite catalog always requires subjective decisions, but we believe PAGER-CAT represents a significant step forward in bringing together the best available estimates of earthquake source parameters and reports of earthquake effects. All information considered in PAGER-CAT is stored as provided in its native catalog so that other users can modify PAGER preferred parameters based on their specific needs or opinions. As with all catalogs, the values of some parameters listed in PAGER-CAT are

  13. Observing Triggered Earthquakes Across Iran with Calibrated Earthquake Locations

    NASA Astrophysics Data System (ADS)

    Karasozen, E.; Bergman, E.; Ghods, A.; Nissen, E.

    2016-12-01

    We investigate earthquake triggering phenomena in Iran by analyzing patterns of aftershock activity around mapped surface ruptures. Iran has an intense level of seismicity (> 40,000 events listed in the ISC Bulletin since 1960) due to it accommodating a significant portion of the continental collision between Arabia and Eurasia. There are nearly thirty mapped surface ruptures associated with earthquakes of M 6-7.5, mostly in eastern and northwestern Iran, offering a rich potential to study the kinematics of earthquake nucleation, rupture propagation, and subsequent triggering. However, catalog earthquake locations are subject to up to 50 km of location bias from the combination of unknown Earth structure and unbalanced station coverage, making it challenging to assess both the rupture directivity of larger events and the spatial patterns of their aftershocks. To overcome this limitation, we developed a new two-tiered multiple-event relocation approach to obtain hypocentral parameters that are minimally biased and have realistic uncertainties. In the first stage, locations of small clusters of well-recorded earthquakes at local spatial scales (100s of events across 100 km length scales) are calibrated either by using near-source arrival times or independent location constraints (e.g. local aftershock studies, InSAR solutions), using an implementation of the Hypocentroidal Decomposition relocation technique called MLOC. Epicentral uncertainties are typically less than 5 km. Then, these events are used as prior constraints in the code BayesLoc, a Bayesian relocation technique that can handle larger datasets, to yield region-wide calibrated hypocenters (1000s of events over 1000 km length scales). With locations and errors both calibrated, the pattern of aftershock activity can reveal the type of the earthquake triggering: dynamic stress changes promote an increase in the seismicity rate in the direction of unilateral propagation, whereas static stress changes should

  14. The Loma Prieta, California, Earthquake of October 17, 1989: Earthquake Occurrence

    USGS Publications Warehouse

    Coordinated by Bakun, William H.; Prescott, William H.

    1993-01-01

    Professional Paper 1550 seeks to understand the M6.9 Loma Prieta earthquake itself. It examines how the fault that generated the earthquake ruptured, searches for and evaluates precursors that may have indicated an earthquake was coming, reviews forecasts of the earthquake, and describes the geology of the earthquake area and the crustal forces that affect this geology. Some significant findings were: * Slip during the earthquake occurred on 35 km of fault at depths ranging from 7 to 20 km. Maximum slip was approximately 2.3 m. The earthquake may not have released all of the strain stored in rocks next to the fault and indicates a potential for another damaging earthquake in the Santa Cruz Mountains in the near future may still exist. * The earthquake involved a large amount of uplift on a dipping fault plane. Pre-earthquake conventional wisdom was that large earthquakes in the Bay area occurred as horizontal displacements on predominantly vertical faults. * The fault segment that ruptured approximately coincided with a fault segment identified in 1988 as having a 30% probability of generating a M7 earthquake in the next 30 years. This was one of more than 20 relevant earthquake forecasts made in the 83 years before the earthquake. * Calculations show that the Loma Prieta earthquake changed stresses on nearby faults in the Bay area. In particular, the earthquake reduced stresses on the Hayward Fault which decreased the frequency of small earthquakes on it. * Geological and geophysical mapping indicate that, although the San Andreas Fault can be mapped as a through going fault in the epicentral region, the southwest dipping Loma Prieta rupture surface is a separate fault strand and one of several along this part of the San Andreas that may be capable of generating earthquakes.

  15. A method for producing digital probabilistic seismic landslide hazard maps

    USGS Publications Warehouse

    Jibson, R.W.; Harp, E.L.; Michael, J.A.

    2000-01-01

    The 1994 Northridge, California, earthquake is the first earthquake for which we have all of the data sets needed to conduct a rigorous regional analysis of seismic slope instability. These data sets include: (1) a comprehensive inventory of triggered landslides, (2) about 200 strong-motion records of the mainshock, (3) 1:24 000-scale geologic mapping of the region, (4) extensive data on engineering properties of geologic units, and (5) high-resolution digital elevation models of the topography. All of these data sets have been digitized and rasterized at 10 m grid spacing using ARC/INFO GIS software on a UNIX computer. Combining these data sets in a dynamic model based on Newmark's permanent-deformation (sliding-block) analysis yields estimates of coseismic landslide displacement in each grid cell from the Northridge earthquake. The modeled displacements are then compared with the digital inventory of landslides triggered by the Northridge earthquake to construct a probability curve relating predicted displacement to probability of failure. This probability function can be applied to predict and map the spatial variability in failure probability in any ground-shaking conditions of interest. We anticipate that this mapping procedure will be used to construct seismic landslide hazard maps that will assist in emergency preparedness planning and in making rational decisions regarding development and construction in areas susceptible to seismic slope failure. ?? 2000 Elsevier Science B.V. All rights reserved.

  16. Surface rupture and vertical deformation associated with 20 May 2016 M6 Petermann Ranges earthquake, Northern Territory, Australia

    NASA Astrophysics Data System (ADS)

    Gold, Ryan; Clark, Dan; King, Tamarah; Quigley, Mark

    2017-04-01

    Surface-rupturing earthquakes in stable continental regions (SCRs) occur infrequently, though when they occur in heavily populated regions the damage and loss of life can be severe (e.g., 2001 Bhuj earthquake). Quantifying the surface-rupture characteristics of these low-probability events is therefore important, both to improve understanding of the on- and off-fault deformation field near the rupture trace and to provide additional constraints on earthquake magnitude to rupture length and displacement, which are critical inputs for seismic hazard calculations. This investigation focuses on the 24 August 2016 M6.0 Petermann Ranges earthquake, Northern Territory, Australia. We use 0.3-0.5 m high-resolution optical Worldview satellite imagery to map the trace of the surface rupture associated with the earthquake. From our mapping, we are able to trace the rupture over a length of 20 km, trending NW, and exhibiting apparent north-side-up motion. To quantify the magnitude of vertical surface deformation, we use stereo Worldview images processed using NASA Ames Stereo Pipeline software to generate pre- and post-earthquake digital terrain models with a spatial resolution of 1.5 to 2 m. The surface scarp is apparent in much of the post-event digital terrain model. Initial efforts to difference the pre- and post-event digital terrain models yield noisy results, though we detect vertical deformation of 0.2 to 0.6 m over length scales of 100 m to 1 km from the mapped trace of the rupture. Ongoing efforts to remove ramps and perform spatial smoothing will improve our understanding of the extent and pattern of vertical deformation. Additionally, we will compare our results with InSAR and field measurements obtained following the earthquake.

  17. The Berkeley Digital Seismic Network

    NASA Astrophysics Data System (ADS)

    Romanowicz, B.; Dreger, D.; Neuhauser, D.; Karavas, W.; Hellweg, M.; Uhrhammer, R.; Lombard, P.; Friday, J.; Lellinger, R.; Gardner, J.; McKenzie, M. R.; Bresloff, C.

    2007-05-01

    Since it began monitoring earthquakes in northern California 120 years ago, the Berkeley Seismological Laboratory (BSL) has been striving to produce the highest quality and most complete seismic data possible in the most modern way. This goal has influenced choices in instrumentation, installation and telemetry, as well as the investment in expertise and manpower. Since the transition to broadband (BB) instrumentation in the mid- 1980s and to a fully digitally telemetered network in the early 1990s, we have continued these efforts. Each of our 25 BB installations includes three component BB seismometers (STS-1s or STS-2) and digital accelerometers to capture the full range of ground motion from distant teleseisms to large, nearby earthquakes (almost 250 dB). The ground motion is recorded on-site by 24 bit dataloggers. Additional environmental parameters, such as temperature and pressure, are also monitored continuously. Many stations record also C-GPS data that is transmitted continuously to the BSL via shared real-time telemetry. The BDSN's first stations were installed in abandoned mines. In the last 15 years, we developed installations using buried shipping containers to reduce environmental noise and provide security and easy access to the equipment. Data are transmitted in real-time at several sampling rates to one or more processing centers, using frame relay, radio, microwave, and/or satellite. Each site has 7-30 days of onsite data storage to guard against data loss during telemetry outages. Each station is supplied with backup batteries to provide power for 3 days. The BDSN real-time data acquisition, earthquake analysis and archiving computers are housed in a building built to "emergency grade" seismic standards, with air conditioning and power backed up by a UPS and a large generator. Data latency and power are monitored by automated processes that alert staff via pager and email. Data completeness and timing quality are automatically assessed on a daily

  18. Napa earthquake: An earthquake in a highly connected world

    NASA Astrophysics Data System (ADS)

    Bossu, R.; Steed, R.; Mazet-Roux, G.; Roussel, F.

    2014-12-01

    The Napa earthquake recently occurred close to Silicon Valley. This makes it a good candidate to study what social networks, wearable objects and website traffic analysis (flashsourcing) can tell us about the way eyewitnesses react to ground shaking. In the first part, we compare the ratio of people publishing tweets and with the ratio of people visiting EMSC (European Mediterranean Seismological Centre) real time information website in the first minutes following the earthquake occurrence to the results published by Jawbone, which show that the proportion of people waking up depends (naturally) on the epicentral distance. The key question to evaluate is whether the proportions of inhabitants tweeting or visiting the EMSC website are similar to the proportion of people waking up as shown by the Jawbone data. If so, this supports the premise that all methods provide a reliable image of the relative ratio of people waking up. The second part of the study focuses on the reaction time for both Twitter and EMSC website access. We show, similarly to what was demonstrated for the Mineral, Virginia, earthquake (Bossu et al., 2014), that hit times on the EMSC website follow the propagation of the P waves and that 2 minutes of website traffic is sufficient to determine the epicentral location of an earthquake on the other side of the Atlantic. We also compare with the publication time of messages on Twitter. Finally, we check whether the number of tweets and the number of visitors relative to the number of inhabitants is correlated to the local level of shaking. Together these results will tell us whether the reaction of eyewitnesses to ground shaking as observed through Twitter and the EMSC website analysis is tool specific (i.e. specific to Twitter or EMSC website) or whether they do reflect people's actual reactions.

  19. Urban Earthquakes - Reducing Building Collapse Through Education

    NASA Astrophysics Data System (ADS)

    Bilham, R.

    2004-12-01

    Fatalities from earthquakes rose from 6000k to 9000k/year in the past decade, yet the ratio of numbers of earthquake fatalities to instantaneous population continues to fall. Since 1950 the ratio declined worldwide by a factor of three, but in some countries the ratio has changed little. E.g in Iran, 1 in 3000 people can expect to die in an earthquake, a percentage that has not changed significantly since 1890. Fatalities from earthquakes remain high in those countries that have traditionally suffered from frequent large earthquakes (Turkey, Iran, Japan, and China), suggesting that the exposure time of recently increased urban populations in other countries may be too short to have interacted with earthquakes with long recurrence intervals. This in turn, suggests that disasters of unprecendented size will occur (more than 1 million fatalities) when future large earthquakes occur close to megacities. However, population growth is most rapid in cities of less than 1 million people in the developing nations, where the financial ability to implement earthquake resistant construction methods is limited. In that structural collapse can often be traced to ignorance about the forces at work in an earthquake, the future collapse of buildings presently under construction could be much reduced were contractors, builders and occupants educated in the principles of earthquake resistant assembly. Education of builders who are tempted to cut assembly costs is likely to be more cost effective than material aid.

  20. Post-earthquake building safety assessments for the Canterbury Earthquakes

    USGS Publications Warehouse

    Marshall, J.; Barnes, J.; Gould, N.; Jaiswal, K.; Lizundia, B.; Swanson, David A.; Turner, F.

    2012-01-01

    This paper explores the post-earthquake building assessment program that was utilized in Christchurch, New Zealand following the Canterbury Sequence of earthquakes beginning with the Magnitude (Mw.) 7.1 Darfield event in September 2010. The aftershocks or triggered events, two of which exceeded Mw 6.0, continued with events in February and June 2011 causing the greatest amount of damage. More than 70,000 building safety assessments were completed following the February event. The timeline and assessment procedures will be discussed including the use of rapid response teams, selection of indicator buildings to monitor damage following aftershocks, risk assessments for demolition of red-tagged buildings, the use of task forces to address management of the heavily damaged downtown area and the process of demolition. Through the post-event safety assessment program that occurred throughout the Canterbury Sequence of earthquakes, many important lessons can be learned that will benefit future response to natural hazards that have potential to damage structures.

  1. Inversion for slip distribution using teleseismic P waveforms: North Palm Springs, Borah Peak, and Michoacan earthquakes

    USGS Publications Warehouse

    Mendoza, C.; Hartzell, S.H.

    1988-01-01

    We have inverted the teleseismic P waveforms recorded by stations of the Global Digital Seismograph Network for the 8 July 1986 North Palm Springs, California, the 28 October 1983 Borah Peak, Idaho, and the 19 September 1985 Michoacan, Mexico, earthquakes to recover the distribution of slip on each of the faults using a point-by-point inversion method with smoothing and positivity constraints. Results of the inversion indicate that the Global digital Seismograph Network data are useful for deriving fault dislocation models for moderate to large events. However, a wide range of frequencies is necessary to infer the distribution of slip on the earthquake fault. Although the long-period waveforms define the size (dimensions and seismic moment) of the earthquake, data at shorter period provide additional constraints on the variation of slip on the fault. Dislocation models obtained for all three earthquakes are consistent with a heterogeneous rupture process where failure is controlled largely by the size and location of high-strength asperity regions. -from Authors

  2. An open repository of earthquake-triggered ground-failure inventories

    USGS Publications Warehouse

    Schmitt, Robert G.; Tanyas, Hakan; Nowicki Jessee, M. Anna; Zhu, Jing; Biegel, Katherine M.; Allstadt, Kate E.; Jibson, Randall W.; Thompson, Eric M.; van Westen, Cees J.; Sato, Hiroshi P.; Wald, David J.; Godt, Jonathan W.; Gorum, Tolga; Xu, Chong; Rathje, Ellen M.; Knudsen, Keith L.

    2017-12-20

    Earthquake-triggered ground failure, such as landsliding and liquefaction, can contribute significantly to losses, but our current ability to accurately include them in earthquake-hazard analyses is limited. The development of robust and widely applicable models requires access to numerous inventories of ground failures triggered by earthquakes that span a broad range of terrains, shaking characteristics, and climates. We present an openly accessible, centralized earthquake-triggered groundfailure inventory repository in the form of a ScienceBase Community to provide open access to these data with the goal of accelerating research progress. The ScienceBase Community hosts digital inventories created by both U.S. Geological Survey (USGS) and non-USGS authors. We present the original digital inventory files (when available) as well as an integrated database with uniform attributes. We also summarize the mapping methodology and level of completeness as reported by the original author(s) for each inventory. This document describes the steps taken to collect, process, and compile the inventories and the process for adding additional ground-failure inventories to the ScienceBase Community in the future.

  3. Update earthquake risk assessment in Cairo, Egypt

    NASA Astrophysics Data System (ADS)

    Badawy, Ahmed; Korrat, Ibrahim; El-Hadidy, Mahmoud; Gaber, Hanan

    2017-07-01

    The Cairo earthquake (12 October 1992; m b = 5.8) is still and after 25 years one of the most painful events and is dug into the Egyptians memory. This is not due to the strength of the earthquake but due to the accompanied losses and damages (561 dead; 10,000 injured and 3000 families lost their homes). Nowadays, the most frequent and important question that should rise is "what if this earthquake is repeated today." In this study, we simulate the same size earthquake (12 October 1992) ground motion shaking and the consequent social-economic impacts in terms of losses and damages. Seismic hazard, earthquake catalogs, soil types, demographics, and building inventories were integrated into HAZUS-MH to produce a sound earthquake risk assessment for Cairo including economic and social losses. Generally, the earthquake risk assessment clearly indicates that "the losses and damages may be increased twice or three times" in Cairo compared to the 1992 earthquake. The earthquake risk profile reveals that five districts (Al-Sahel, El Basateen, Dar El-Salam, Gharb, and Madinat Nasr sharq) lie in high seismic risks, and three districts (Manshiyat Naser, El-Waily, and Wassat (center)) are in low seismic risk level. Moreover, the building damage estimations reflect that Gharb is the highest vulnerable district. The analysis shows that the Cairo urban area faces high risk. Deteriorating buildings and infrastructure make the city particularly vulnerable to earthquake risks. For instance, more than 90 % of the estimated buildings damages are concentrated within the most densely populated (El Basateen, Dar El-Salam, Gharb, and Madinat Nasr Gharb) districts. Moreover, about 75 % of casualties are in the same districts. Actually, an earthquake risk assessment for Cairo represents a crucial application of the HAZUS earthquake loss estimation model for risk management. Finally, for mitigation, risk reduction, and to improve the seismic performance of structures and assure life safety

  4. Revisiting the 1872 Owens Valley, California, Earthquake

    USGS Publications Warehouse

    Hough, S.E.; Hutton, K.

    2008-01-01

    The 26 March 1872 Owens Valley earthquake is among the largest historical earthquakes in California. The felt area and maximum fault displacements have long been regarded as comparable to, if not greater than, those of the great San Andreas fault earthquakes of 1857 and 1906, but mapped surface ruptures of the latter two events were 2-3 times longer than that inferred for the 1872 rupture. The preferred magnitude estimate of the Owens Valley earthquake has thus been 7.4, based largely on the geological evidence. Reinterpreting macroseismic accounts of the Owens Valley earthquake, we infer generally lower intensity values than those estimated in earlier studies. Nonetheless, as recognized in the early twentieth century, the effects of this earthquake were still generally more dramatic at regional distances than the macroseismic effects from the 1906 earthquake, with light damage to masonry buildings at (nearest-fault) distances as large as 400 km. Macroseismic observations thus suggest a magnitude greater than that of the 1906 San Francisco earthquake, which appears to be at odds with geological observations. However, while the mapped rupture length of the Owens Valley earthquake is relatively low, the average slip was high. The surface rupture was also complex and extended over multiple fault segments. It was first mapped in detail over a century after the earthquake occurred, and recent evidence suggests it might have been longer than earlier studies indicated. Our preferred magnitude estimate is Mw 7.8-7.9, values that we show are consistent with the geological observations. The results of our study suggest that either the Owens Valley earthquake was larger than the 1906 San Francisco earthquake or that, by virtue of source properties and/or propagation effects, it produced systematically higher ground motions at regional distances. The latter possibility implies that some large earthquakes in California will generate significantly larger ground motions than San

  5. Focal mechanisms of earthquakes in Mongolia

    NASA Astrophysics Data System (ADS)

    Sodnomsambuu, D.; Natalia, R.; Gangaadorj, B.; Munkhuu, U.; Davaasuren, G.; Danzansan, E.; Yan, R.; Valentina, M.; Battsetseg, B.

    2011-12-01

    Focal mechanism data provide information on the relative magnitudes of the principal stresses, so that a tectonic regime can be assigned. Especially such information is useful for the study of intraplate seismic active regions. A study of earthquake focal mechanisms in the territory of Mongolia as landlocked and intraplate region was conducted. We present map of focal mechanisms of earthquakes with M4.5 which occurred in Mongolia and neighboring regions. Focal mechanisms solutions were constrained by the first motion solutions, as well as by waveform modeling, particularly CMT solutions. Four earthquakes have been recorded in Mongolia in XX century with magnitude more than 8, the 1905 M7.9 Tsetserleg and M8.4 Bolnai earthquakes, the 1931 M8.0 Fu Yun earthquake, the 1957 M8.1 Gobi-Altai earthquake. However the map of focal mechanisms of earthquakes in Mongolia allows seeing all seismic active structures: Gobi Altay, Mongolian Altay, active fringe of Hangay dome, Hentii range etc. Earthquakes in the most of Mongolian territory and neighboring China regions are characterized by strike-slip and reverse movements. Strike-slip movements also are typical for earthquakes in Altay Range in Russia. The north of Mongolia and south part of the Baikal area is a region where have been occurred earthquakes with different focal mechanisms. This region is a zone of the transition between compressive regime associated to India-Eurasian collision and extensive structures localized in north of the country as Huvsgul area and Baykal rift. Earthquakes in the Baikal basin itself are characterized by normal movements. Earthquakes in Trans-Baikal zone and NW of Mongolia are characterized dominantly by strike-slip movements. Analysis of stress-axis orientations, the tectonic stress tensor is presented. The map of focal mechanisms of earthquakes in Mongolia could be useful tool for researchers in their study on Geodynamics of Central Asia, particularly of Mongolian and Baikal regions.

  6. A smartphone application for earthquakes that matter!

    NASA Astrophysics Data System (ADS)

    Bossu, Rémy; Etivant, Caroline; Roussel, Fréderic; Mazet-Roux, Gilles; Steed, Robert

    2014-05-01

    Smartphone applications have swiftly become one of the most popular tools for rapid reception of earthquake information for the public, some of them having been downloaded more than 1 million times! The advantages are obvious: wherever someone's own location is, they can be automatically informed when an earthquake has struck. Just by setting a magnitude threshold and an area of interest, there is no longer the need to browse the internet as the information reaches you automatically and instantaneously! One question remains: are the provided earthquake notifications always relevant for the public? What are the earthquakes that really matters to laypeople? One clue may be derived from some newspaper reports that show that a while after damaging earthquakes many eyewitnesses scrap the application they installed just after the mainshock. Why? Because either the magnitude threshold is set too high and many felt earthquakes are missed, or it is set too low and the majority of the notifications are related to unfelt earthquakes thereby only increasing anxiety among the population at each new update. Felt and damaging earthquakes are the ones that matter the most for the public (and authorities). They are the ones of societal importance even when of small magnitude. A smartphone application developed by EMSC (Euro-Med Seismological Centre) with the financial support of the Fondation MAIF aims at providing suitable notifications for earthquakes by collating different information threads covering tsunamigenic, potentially damaging and felt earthquakes. Tsunamigenic earthquakes are considered here to be those ones that are the subject of alert or information messages from the PTWC (Pacific Tsunami Warning Centre). While potentially damaging earthquakes are identified through an automated system called EQIA (Earthquake Qualitative Impact Assessment) developed and operated at EMSC. This rapidly assesses earthquake impact by comparing the population exposed to each expected

  7. Istanbul Earthquake Early Warning and Rapid Response System

    NASA Astrophysics Data System (ADS)

    Erdik, M. O.; Fahjan, Y.; Ozel, O.; Alcik, H.; Aydin, M.; Gul, M.

    2003-12-01

    As part of the preparations for the future earthquake in Istanbul a Rapid Response and Early Warning system in the metropolitan area is in operation. For the Early Warning system ten strong motion stations were installed as close as possible to the fault zone. Continuous on-line data from these stations via digital radio modem provide early warning for potentially disastrous earthquakes. Considering the complexity of fault rupture and the short fault distances involved, a simple and robust Early Warning algorithm, based on the exceedance of specified threshold time domain amplitude levels is implemented. The band-pass filtered accelerations and the cumulative absolute velocity (CAV) are compared with specified threshold levels. When any acceleration or CAV (on any channel) in a given station exceeds specific threshold values it is considered a vote. Whenever we have 2 station votes within selectable time interval, after the first vote, the first alarm is declared. In order to specify the appropriate threshold levels a data set of near field strong ground motions records form Turkey and the world has been analyzed. Correlations among these thresholds in terms of the epicenter distance the magnitude of the earthquake have been studied. The encrypted early warning signals will be communicated to the respective end users by UHF systems through a "service provider" company. The users of the early warning signal will be power and gas companies, nuclear research facilities, critical chemical factories, subway system and several high-rise buildings. Depending on the location of the earthquake (initiation of fault rupture) and the recipient facility the alarm time can be as high as about 8s. For the rapid response system one hundred 18 bit-resolution strong motion accelerometers were placed in quasi-free field locations (basement of small buildings) in the populated areas of the city, within an area of approximately 50x30km, to constitute a network that will enable early

  8. Microearthquake networks and earthquake prediction

    USGS Publications Warehouse

    Lee, W.H.K.; Steward, S. W.

    1979-01-01

    A microearthquake network is a group of highly sensitive seismographic stations designed primarily to record local earthquakes of magnitudes less than 3. Depending on the application, a microearthquake network will consist of several stations or as many as a few hundred . They are usually classified as either permanent or temporary. In a permanent network, the seismic signal from each is telemetered to a central recording site to cut down on the operating costs and to allow more efficient and up-to-date processing of the data. However, telemetering can restrict the location sites because of the line-of-site requirement for radio transmission or the need for telephone lines. Temporary networks are designed to be extremely portable and completely self-contained so that they can be very quickly deployed. They are most valuable for recording aftershocks of a major earthquake or for studies in remote areas.  

  9. The 2016 Kumamoto earthquake sequence.

    PubMed

    Kato, Aitaro; Nakamura, Kouji; Hiyama, Yohei

    2016-01-01

    Beginning in April 2016, a series of shallow, moderate to large earthquakes with associated strong aftershocks struck the Kumamoto area of Kyushu, SW Japan. An M j 7.3 mainshock occurred on 16 April 2016, close to the epicenter of an M j 6.5 foreshock that occurred about 28 hours earlier. The intense seismicity released the accumulated elastic energy by right-lateral strike slip, mainly along two known, active faults. The mainshock rupture propagated along multiple fault segments with different geometries. The faulting style is reasonably consistent with regional deformation observed on geologic timescales and with the stress field estimated from seismic observations. One striking feature of this sequence is intense seismic activity, including a dynamically triggered earthquake in the Oita region. Following the mainshock rupture, postseismic deformation has been observed, as well as expansion of the seismicity front toward the southwest and northwest.

  10. Great East Japan Earthquake Tsunami

    NASA Astrophysics Data System (ADS)

    Iijima, Y.; Minoura, K.; Hirano, S.; Yamada, T.

    2011-12-01

    The 11 March 2011, Mw 9.0 Great East Japan Earthquake, already among the most destructive earthquakes in modern history, emanated from a fault rupture that extended an estimated 500 km along the Pacific coast of Honshu. This earthquake is the fourth among five of the strongest temblors since AD 1900 and the largest in Japan since modern instrumental recordings began 130 years ago. The earthquake triggered a huge tsunami, which invaded the seaside areas of the Pacific coast of East Japan, causing devastating damages on the coast. Artificial structures were destroyed and planted forests were thoroughly eroded. Inrush of turbulent flows washed backshore areas and dunes. Coastal materials including beach sand were transported onto inland areas by going-up currents. Just after the occurrence of the tsunami, we started field investigation of measuring thickness and distribution of sediment layers by the tsunami and the inundation depth of water in Sendai plain. Ripple marks showing direction of sediment transport were the important object of observation. We used a soil auger for collecting sediments in the field, and sediment samples were submitted for analyzing grain size and interstitial water chemistry. Satellite images and aerial photographs are very useful for estimating the hydrogeological effects of tsunami inundation. We checked the correspondence of micro-topography, vegetation and sediment covering between before and after the tsunami. The most conspicuous phenomenon is the damage of pine forests planted in the purpose of preventing sand shifting. About ninety-five percent of vegetation coverage was lost during the period of rapid currents changed from first wave. The landward slopes of seawalls were mostly damaged and destroyed. Some aerial photographs leave detailed records of wave destruction just behind seawalls, which shows the occurrence of supercritical flows. The large-scale erosion of backshore behind seawalls is interpreted to have been caused by

  11. Earthquake watch to be discussed

    NASA Astrophysics Data System (ADS)

    Katzoff, Judith A.

    The most intensive earthquake monitoring program ever mounted in this country is going on near Parkfield, Calif., about midway between Los Angeles and San Francisco on the San Andreas fault. Although no particularly large or destructive quake is feared in Parkfield, the regularity with which earthquakes have occurred there in the past makes the site unique. Since the next quake has been forecast for 1988 (±5 years), seismologists have decided to blanket the area with data-gathering equipment in hopes of having front-row seats for the expected seismic show. The studies in Parkfield will be the topic of an all-day session sponsored by the Seismology Section on Friday, December 13, at the AGU Fall Meeting in San Francisco, Calif.

  12. Earthquake ground motion: Chapter 3

    USGS Publications Warehouse

    Luco, Nicolas; Kircher, Charles A.; Crouse, C. B.; Charney, Finley; Haselton, Curt B.; Baker, Jack W.; Zimmerman, Reid; Hooper, John D.; McVitty, William; Taylor, Andy

    2016-01-01

    Most of the effort in seismic design of buildings and other structures is focused on structural design. This chapter addresses another key aspect of the design process—characterization of earthquake ground motion into parameters for use in design. Section 3.1 describes the basis of the earthquake ground motion maps in the Provisions and in ASCE 7 (the Standard). Section 3.2 has examples for the determination of ground motion parameters and spectra for use in design. Section 3.3 describes site-specific ground motion requirements and provides example site-specific design and MCER response spectra and example values of site-specific ground motion parameters. Section 3.4 discusses and provides an example for the selection and scaling of ground motion records for use in various types of response history analysis permitted in the Standard.

  13. The 2016 Kumamoto earthquake sequence

    PubMed Central

    KATO, Aitaro; NAKAMURA, Kouji; HIYAMA, Yohei

    2016-01-01

    Beginning in April 2016, a series of shallow, moderate to large earthquakes with associated strong aftershocks struck the Kumamoto area of Kyushu, SW Japan. An Mj 7.3 mainshock occurred on 16 April 2016, close to the epicenter of an Mj 6.5 foreshock that occurred about 28 hours earlier. The intense seismicity released the accumulated elastic energy by right-lateral strike slip, mainly along two known, active faults. The mainshock rupture propagated along multiple fault segments with different geometries. The faulting style is reasonably consistent with regional deformation observed on geologic timescales and with the stress field estimated from seismic observations. One striking feature of this sequence is intense seismic activity, including a dynamically triggered earthquake in the Oita region. Following the mainshock rupture, postseismic deformation has been observed, as well as expansion of the seismicity front toward the southwest and northwest. PMID:27725474

  14. Analysis of the enhanced negative correlation between electron density and electron temperature related to earthquakes

    NASA Astrophysics Data System (ADS)

    Shen, X. H.; Zhang, X.; Liu, J.; Zhao, S. F.; Yuan, G. P.

    2015-04-01

    Ionospheric perturbations in plasma parameters have been observed before large earthquakes, but the correlation between different parameters has been less studied in previous research. The present study is focused on the relationship between electron density (Ne) and temperature (Te) observed by the DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) satellite during local nighttime, in which a positive correlation has been revealed near the equator and a weak correlation at mid- and low latitudes over both hemispheres. Based on this normal background analysis, the negative correlation with the lowest percent in all Ne and Te points is studied before and after large earthquakes at mid- and low latitudes. The multiparameter observations exhibited typical synchronous disturbances before the Chile M8.8 earthquake in 2010 and the Pu'er M6.4 in 2007, and Te varied inversely with Ne over the epicentral areas. Moreover, statistical analysis has been done by selecting the orbits at a distance of 1000 km and ±7 days before and after the global earthquakes. Enhanced negative correlation coefficients lower than -0.5 between Ne and Te are found in 42% of points to be connected with earthquakes. The correlation median values at different seismic levels show a clear decrease with earthquakes larger than 7. Finally, the electric-field-coupling model is discussed; furthermore, a digital simulation has been carried out by SAMI2 (Sami2 is Another Model of the Ionosphere), which illustrates that the external electric field in the ionosphere can strengthen the negative correlation in Ne and Te at a lower latitude relative to the disturbed source due to the effects of the geomagnetic field. Although seismic activity is not the only source to cause the inverse Ne-Te variations, the present results demonstrate one possibly useful tool in seismo-electromagnetic anomaly differentiation, and a comprehensive analysis with multiple parameters helps to

  15. Dim prospects for earthquake prediction

    NASA Astrophysics Data System (ADS)

    Geller, Robert J.

    I was misquoted by C. Lomnitz's [1998] Forum letter (Eos, August 4, 1998, p. 373), which said: [I wonder whether Sasha Gusev [1998] actually believes that branding earthquake prediction a ‘proven nonscience’ [Geller, 1997a] is a paradigm for others to copy.”Readers are invited to verify for themselves that neither “proven nonscience” norv any similar phrase was used by Geller [1997a].

  16. Mechanics of Multifault Earthquake Ruptures

    NASA Astrophysics Data System (ADS)

    Fletcher, J. M.; Oskin, M. E.; Teran, O.

    2015-12-01

    The 2010 El Mayor-Cucapah earthquake of magnitude Mw 7.2 produced the most complex rupture ever documented on the Pacific-North American plate margin, and the network of high- and low-angle faults activated in the event record systematic changes in kinematics with fault orientation. Individual faults have a broad and continuous spectrum of slip sense ranging from endmember dextral strike slip to normal slip, and even faults with thrust sense of dip slip were commonly observed in the aftershock sequence. Patterns of coseismic slip are consistent with three-dimensional constrictional strain and show that integrated transtensional shearing can be accommodated in a single earthquake. Stress inversions of coseismic surface rupture and aftershock focal mechanisms define two coaxial, but permuted stress states. The maximum (σ1) and intermediate (σ2) principal stresses are close in magnitude, but flip orientations due to topography- and density-controlled gradients in lithostatic load along the length of the rupture. Although most large earthquakes throughout the world activate slip on multiple faults, the mechanical conditions of their genesis remain poorly understood. Our work attempts to answer several key questions. 1) Why do complex fault systems exist? They must do something that simple, optimally-oriented fault systems cannot because the two types of faults are commonly located in close proximity. 2) How are faults with diverse orientations and slip senses prepared throughout the interseismic period to fail spontaneously together in a single earthquake? 3) Can a single stress state produce multi-fault failure? 4) Are variations in pore pressure, friction and cohesion required to produce simultaneous rupture? 5) How is the fabric of surface rupture affected by variations in orientation, kinematics, total geologic slip and fault zone architecture?

  17. Earthquake effects at nuclear reactor facilities: San Fernando earthquake of February 9th, 1971

    SciTech Connect

    Howard, G.; Ibanez, P.; Matthiesen, F.

    1972-02-01

    The effects of the San Fernando earthquake of February 9, 1971 on 26 reactor facilities located in California, Arizona, and Nevada are reported. The safety performance of the facilities during the earthquake is discussed. (JWR)

  18. Large-Scale Earthquake Countermeasures Act and the Earthquake Prediction Council in Japan

    SciTech Connect

    Rikitake, T.

    1979-08-07

    The Large-Scale Earthquake Countermeasures Act was enacted in Japan in December 1978. This act aims at mitigating earthquake hazards by designating an area to be an area under intensified measures against earthquake disaster, such designation being based on long-term earthquake prediction information, and by issuing an earthquake warnings statement based on imminent prediction information, when possible. In an emergency case as defined by the law, the prime minister will be empowered to take various actions which cannot be taken at ordinary times. For instance, he may ask the Self-Defense Force to come into the earthquake-threatened area before the earthquake occurrence.more » A Prediction Council has been formed in order to evaluate premonitory effects that might be observed over the Tokai area, which was designated an area under intensified measures against earthquake disaster some time in June 1979. An extremely dense observation network has been constructed over the area.« less

  19. On Earthquake Prediction in Japan

    PubMed Central

    UYEDA, Seiya

    2013-01-01

    Japan’s National Project for Earthquake Prediction has been conducted since 1965 without success. An earthquake prediction should be a short-term prediction based on observable physical phenomena or precursors. The main reason of no success is the failure to capture precursors. Most of the financial resources and manpower of the National Project have been devoted to strengthening the seismographs networks, which are not generally effective for detecting precursors since many of precursors are non-seismic. The precursor research has never been supported appropriately because the project has always been run by a group of seismologists who, in the present author’s view, are mainly interested in securing funds for seismology — on pretense of prediction. After the 1995 Kobe disaster, the project decided to give up short-term prediction and this decision has been further fortified by the 2011 M9 Tohoku Mega-quake. On top of the National Project, there are other government projects, not formally but vaguely related to earthquake prediction, that consume many orders of magnitude more funds. They are also un-interested in short-term prediction. Financially, they are giants and the National Project is a dwarf. Thus, in Japan now, there is practically no support for short-term prediction research. Recently, however, substantial progress has been made in real short-term prediction by scientists of diverse disciplines. Some promising signs are also arising even from cooperation with private sectors. PMID:24213204

  20. Pre-earthquake Magnetic Pulses

    NASA Astrophysics Data System (ADS)

    Scoville, J.; Heraud, J. A.; Freund, F. T.

    2015-12-01

    A semiconductor model of rocks is shown to describe unipolar magnetic pulses, a phenomenon that has been observed prior to earthquakes. These pulses are suspected to be generated deep in the Earth's crust, in and around the hypocentral volume, days or even weeks before earth quakes. Their extremely long wavelength allows them to pass through kilometers of rock. Interestingly, when the sources of these pulses are triangulated, the locations coincide with the epicenters of future earthquakes. We couple a drift-diffusion semiconductor model to a magnetic field in order to describe the electromagnetic effects associated with electrical currents flowing within rocks. The resulting system of equations is solved numerically and it is seen that a volume of rock may act as a diode that produces transient currents when it switches bias. These unidirectional currents are expected to produce transient unipolar magnetic pulses similar in form, amplitude, and duration to those observed before earthquakes, and this suggests that the pulses could be the result of geophysical semiconductor processes.

  1. Local earthquake tomography of Scotland

    NASA Astrophysics Data System (ADS)

    Luckett, Richard; Baptie, Brian

    2015-03-01

    Scotland is a relatively aseismic region for the use of local earthquake tomography, but 40 yr of earthquakes recorded by a good and growing network make it possible. A careful selection is made from the earthquakes located by the British Geological Survey (BGS) over the last four decades to provide a data set maximising arrival time accuracy and ray path coverage of Scotland. A large number of 1-D velocity models with different layer geometries are considered and differentiated by employing quarry blasts as ground-truth events. Then, SIMULPS14 is used to produce a robust 3-D tomographic P-wave velocity model for Scotland. In areas of high resolution the model shows good agreement with previously published interpretations of seismic refraction and reflection experiments. However, the model shows relatively little lateral variation in seismic velocity except at shallow depths, where sedimentary basins such as the Midland Valley are apparent. At greater depths, higher velocities in the northwest parts of the model suggest that the thickness of crust increases towards the south and east. This observation is also in agreement with previous studies. Quarry blasts used as ground truth events and relocated with the preferred 3-D model are shown to be markedly more accurate than when located with the existing BGS 1-D velocity model.

  2. Earthquakes in Virginia and vicinity 1774 - 2004

    USGS Publications Warehouse

    Tarr, Arthur C.; Wheeler, Russell L.

    2006-01-01

    This map summarizes two and a third centuries of earthquake activity. The seismic history consists of letters, journals, diaries, and newspaper and scholarly articles that supplement seismograph recordings (seismograms) dating from the early twentieth century to the present. All of the pre-instrumental (historical) earthquakes were large enough to be felt by people or to cause shaking damage to buildings and their contents. Later, widespread use of seismographs meant that tremors too small or distant to be felt could be detected and accurately located. Earthquakes are a legitimate concern in Virginia and parts of adjacent States. Moderate earthquakes cause slight local damage somewhere in the map area about twice a decade on the average. Additionally, many buildings in the map area were constructed before earthquake protection was added to local building codes. The large map shows all historical and instrumentally located earthquakes from 1774 through 2004.

  3. Insignificant solar-terrestrial triggering of earthquakes

    USGS Publications Warehouse

    Love, Jeffrey J.; Thomas, Jeremy N.

    2013-01-01

    We examine the claim that solar-terrestrial interaction, as measured by sunspots, solar wind velocity, and geomagnetic activity, might play a role in triggering earthquakes. We count the number of earthquakes having magnitudes that exceed chosen thresholds in calendar years, months, and days, and we order these counts by the corresponding rank of annual, monthly, and daily averages of the solar-terrestrial variables. We measure the statistical significance of the difference between the earthquake-number distributions below and above the median of the solar-terrestrial averages by χ2 and Student's t tests. Across a range of earthquake magnitude thresholds, we find no consistent and statistically significant distributional differences. We also introduce time lags between the solar-terrestrial variables and the number of earthquakes, but again no statistically significant distributional difference is found. We cannot reject the null hypothesis of no solar-terrestrial triggering of earthquakes.

  4. Earthquakes at North Atlantic passive margins

    SciTech Connect

    Gregersen, S.; Basham, P.W.

    1989-01-01

    The main focus of this volume is the earthquakes that occur at and near the continental margins on both sides of the North Atlantic. The book, which contains the proceedings of the NATO workshop on Causes and Effects of Earthquakes at Passive Margins and in Areas of Postglacial Rebound on Both Sides of the North Atlantic, draws together the fields of geophysics, geology and geodesy to address the stress and strain in the Earth's crust. The resulting earthquakes produced on ancient geological fault zones and the associated seismic hazards these pose to man are also addressed. Postglacial rebound in Northmore » America and Fennoscandia is a minor source of earthquakes today, during the interglacial period, but evidence is presented to suggest that the ice sheets suppressed earthquake strain while they were in place, and released this strain as a pulse of significant earthquakes after the ice melted about 9000 years ago.« less

  5. The role of deterministic analyses and seismotectonic data in earthquake risk assessment, Istanbul, Turkey.

    NASA Astrophysics Data System (ADS)

    Pondard, Nicolas; Armijo, Rolando; King, Geoffrey C. P.; Meyer, Bertrand; Ucarkus, Gulsen

    2010-05-01

    Seismotectonic methods allowing quantitative measures of the frequency and severity of earthquakes have greatly advanced over the last 30 years, aided by high-resolution imagery, digital topography and modern techniques for dating. During the same period, deterministic models based on the physics of earthquakes (Coulomb stress interactions) have been extensively developed to explain the distribution of earthquakes in space and time. Seismotectonic data and Coulomb Stress models provide valuable information on seismic hazard and could assist the public policy, disaster risk management and financial risk transfer communities to make more informed decisions around their strategic planning and risk management activities. The Sea of Marmara and Istanbul regions (North Anatolian Fault, NAF) are among the most appropriate on Earth to analyse seismic hazard, because reliable data covers almost completely two seismic cycles (the past ~500 years). Earthquake ruptures associated with historical events have been found in the direct vicinity of the city, on the Marmara sea floor. The MARMARASCARPS cruise using an unmanned submersible (ROV) provides direct observations to study the morphology and geology of those ruptures, their distribution and geometry. These observations are crucial to quantify the magnitude of past earthquakes along the submarine fault system (e.g. 1894, 1912, 1999, M > 7). In particular, the identification of a break continuous over 60 km with a right-lateral slip of 5 m, corresponding probably to the offshore extension of the Ganos earthquake rupture (1912, Ms 7.4), modifies substantially our understanding of the current state of loading along the NAF next to Istanbul. Coulomb stress analysis is used to characterise loading evolution in well-identified fault segments, including secular loading from below and lateral loading imposed by the occurrence of previous earthquakes. The 20th century earthquake sequence in the region of Istanbul is modelled using

  6. St. Louis Area Earthquake Hazards Mapping Project - A Progress Report-November 2008

    USGS Publications Warehouse

    Karadeniz, D.; Rogers, J.D.; Williams, R.A.; Cramer, C.H.; Bauer, R.A.; Hoffman, D.; Chung, J.; Hempen, G.L.; Steckel, P.H.; Boyd, O.L.; Watkins, C.M.; McCallister, N.S.; Schweig, E.

    2009-01-01

    St. Louis has experienced minor earthquake damage at least 12 times in the past 200 years. Because of this history and its proximity to known active earthquake zones, the St. Louis Area Earthquake Hazards Mapping Project (SLAEHMP) is producing digital maps that show variability of earthquake hazards, including liquefaction and ground shaking, in the St. Louis area. The maps will be available free via the internet. Although not site specific enough to indicate the hazard at a house-by-house resolution, they can be customized by the user to show specific areas of interest, such as neighborhoods or transportation routes. Earthquakes currently cannot be predicted, but scientists can estimate how strongly the ground is likely to shake as the result of an earthquake. Earthquake hazard maps provide one way of conveying such estimates. The U.S. Geological Survey (USGS), which produces earthquake hazard maps for the Nation, is working with local partners to develop detailed maps for urban areas vulnerable to strong ground shaking. These partners, which along with the USGS comprise the SLAEHMP, include the Missouri University of Science and Technology-Rolla (Missouri S&T), Missouri Department of Natural Resources (MDNR), Illinois State Geological Survey (ISGS), Saint Louis University, Missouri State Emergency Management Agency, and URS Corporation. Preliminary hazard maps covering a test portion of the 29-quadrangle St. Louis study area have been produced and are currently being evaluated by the SLAEHMP. A USGS Fact Sheet summarizing this project was produced and almost 1000 copies have been distributed at several public outreach meetings and field trips that have featured the SLAEHMP (Williams and others, 2007). In addition, a USGS website focusing on the SLAEHMP, which provides links to project results and relevant earthquake hazard information, can be found at: http://earthquake.usgs.gov/regional/ceus/urban_map/st_louis/index.php. This progress report summarizes the

  7. If pandas scream. an earthquake is coming

    SciTech Connect

    Magida, P.

    Feature article:Use of the behavior of animals to predict weather has spanned several ages and dozens of countries. While animals may behave in diverse ways to indicate weather changes, they all tend to behave in more or less the same way before earthquakes. The geophysical community in the U.S. has begun testing animal behavior before earthquakes. It has been determined that animals have the potential of acting as accurate geosensors to detect earthquakes before they occur. (5 drawings)

  8. The global distribution of magnitude 9 earthquakes

    NASA Astrophysics Data System (ADS)

    McCaffrey, R.

    2011-12-01

    The 2011 Tohoku M9 earthquake once again caught some in the earthquake community by surprise. The expectation of these massive quakes has been driven in the past by the over-reliance on our short, incomplete history of earthquakes and causal relationships derived from it. The logic applied is that if a great earthquake has not happened in the past, that we know of, one cannot happen in the future. Using the ~100-year global earthquake history, seismologists have promoted relationships between maximum earthquake sizes and other properties of subduction zones, leading to the notion that some subduction zones, like the Japan Trench, would never produce a magnitude ~9 event. The 2004 Andaman Mw = 9.2 earthquake, that occurred where there is slow subduction of old crust and a history of only moderate-sized earthquakes, seriously undermined such ideas. Given multi-century return times of the greatest earthquakes, ignorance of those return times and our very limited observation span, I suggest that we cannot yet make such determinations. Alternatively, using the length of a subduction zone that is available for slip as the predominant factor in determining maximum earthquake size, we cannot rule out that any subduction zone of a few hundred kilometers or more in length may be capable of producing a magnitude 9 or larger earthquake. Based on this method, the expected maximum size for the Japan Trench was 9.0 (McCaffrey, Geology, p. 263, 2008). The same approach portends a M > 9 for Java, with twice the population density as Honshu and much lower building standards. The Java Trench, and others where old crust subducts (Hikurangi, Marianas, Tonga, Kermadec), require increased awareness of the possibility for a great earthquake.

  9. NEIC; the National Earthquake Information Center

    USGS Publications Warehouse

    Masse, R.P.; Needham, R.E.

    1989-01-01

    At least 9,500 people were killed, 30,000 were injured and 100,000 were left homeless by this earthquake. According to some unconfirmed reports, the death toll from this earthquake may have been as high as 35,000. this earthquake is estimated to have seriously affected an area of 825,000 square kilometers, caused between 3 and 4 billion dollars in damage, and been felt by 20 million people. 

  10. The Southern California Earthquake Survival Program

    USGS Publications Warehouse

    Harris, J.M.

    1989-01-01

    In July 1988, the Los Angeles County Board of Supervisors directed the Chief Administrative Office to develop an educational program aimed at improving earthquake preparedness among Los Angeles County residents. the board recognized that current earthquake education efforts were not only insufficient, but also often confusing and costly. The board unanimously approved the development of a program that would make earthquake preparedness a year-long effort by encouraging residents to take a different precaution each month. 

  11. Post earthquake recovery in natural gas systems--1971 San Fernando Earthquake

    SciTech Connect

    Johnson, W.T. Jr.

    1983-01-01

    In this paper a concise summary of the post earthquake investigations for the 1971 San Fernando Earthquake is presented. The effects of the earthquake upon building and other above ground structures are briefly discussed. Then the damages and subsequent repairs in the natural gas systems are reported.

  12. Earthquake Shaking - Finding the "Hot Spots"

    USGS Publications Warehouse

    Field, Edward; Jones, Lucile; Jordan, Tom; Benthien, Mark; Wald, Lisa

    2001-01-01

    A new Southern California Earthquake Center study has quantified how local geologic conditions affect the shaking experienced in an earthquake. The important geologic factors at a site are softness of the rock or soil near the surface and thickness of the sediments above hard bedrock. Even when these 'site effects' are taken into account, however, each earthquake exhibits unique 'hotspots' of anomalously strong shaking. Better predictions of strong ground shaking will therefore require additional geologic data and more comprehensive computer simulations of individual earthquakes.

  13. Statistical tests of simple earthquake cycle models

    NASA Astrophysics Data System (ADS)

    DeVries, Phoebe M. R.; Evans, Eileen L.

    2016-12-01

    A central goal of observing and modeling the earthquake cycle is to forecast when a particular fault may generate an earthquake: a fault late in its earthquake cycle may be more likely to generate an earthquake than a fault early in its earthquake cycle. Models that can explain geodetic observations throughout the entire earthquake cycle may be required to gain a more complete understanding of relevant physics and phenomenology. Previous efforts to develop unified earthquake models for strike-slip faults have largely focused on explaining both preseismic and postseismic geodetic observations available across a few faults in California, Turkey, and Tibet. An alternative approach leverages the global distribution of geodetic and geologic slip rate estimates on strike-slip faults worldwide. Here we use the Kolmogorov-Smirnov test for similarity of distributions to infer, in a statistically rigorous manner, viscoelastic earthquake cycle models that are inconsistent with 15 sets of observations across major strike-slip faults. We reject a large subset of two-layer models incorporating Burgers rheologies at a significance level of α = 0.05 (those with long-term Maxwell viscosities ηM < 4.0 × 1019 Pa s and ηM > 4.6 × 1020 Pa s) but cannot reject models on the basis of transient Kelvin viscosity ηK. Finally, we examine the implications of these results for the predicted earthquake cycle timing of the 15 faults considered and compare these predictions to the geologic and historical record.

  14. Streamflow and water well responses to earthquakes.

    PubMed

    Montgomery, David R; Manga, Michael

    2003-06-27

    Earthquake-induced crustal deformation and ground shaking can alter stream flow and water levels in wells through consolidation of surficial deposits, fracturing of solid rocks, aquifer deformation, and the clearing of fracture-filling material. Although local conditions affect the type and amplitude of response, a compilation of reported observations of hydrological response to earthquakes indicates that the maximum distance to which changes in stream flow and water levels in wells have been reported is related to earthquake magnitude. Detectable streamflow changes occur in areas within tens to hundreds of kilometers of the epicenter, whereas changes in groundwater levels in wells can occur hundreds to thousands of kilometers from earthquake epicenters.

  15. Earthquakes induced by fluid injection and explosion

    USGS Publications Warehouse

    Healy, J.H.; Hamilton, R.M.; Raleigh, C.B.

    1970-01-01

    Earthquakes generated by fluid injection near Denver, Colorado, are compared with earthquakes triggered by nuclear explosion at the Nevada Test Site. Spatial distributions of the earthquakes in both cases are compatible with the hypothesis that variation of fluid pressure in preexisting fractures controls the time distribution of the seismic events in an "aftershock" sequence. We suggest that the fluid pressure changes may also control the distribution in time and space of natural aftershock sequences and of earthquakes that have been reported near large reservoirs. ?? 1970.

  16. Real Time Earthquake Information System in Japan

    NASA Astrophysics Data System (ADS)

    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

  17. Luzon earthquake strongest in 90 years

    NASA Astrophysics Data System (ADS)

    The magnitude 7.7 Philippine earthquake that took place 2 weeks ago was the strongest recorded on the island of Luzon in nearly 90 years and the strongest in all of the Philippines in nearly 14 years, according to the U.S. Geological Survey.The earthquake occurred 60 miles north of Manila and was the third strongest recorded on Luzon, exceeded only by an earthquake with an estimated magnitude of 7.8, on December 14, 1901, near Lucena, about 80 miles southeast of Manila, and an earthquake with an estimated magnitude of 7.9 on August 15, 1897, off the northwest coast of Luzon.

  18. Thermal Infrared Anomalies of Several Strong Earthquakes

    PubMed Central

    Wei, Congxin; Guo, Xiao; Qin, Manzhong

    2013-01-01

    In the history of earthquake thermal infrared research, it is undeniable that before and after strong earthquakes there are significant thermal infrared anomalies which have been interpreted as preseismic precursor in earthquake prediction and forecasting. In this paper, we studied the characteristics of thermal radiation observed before and after the 8 great earthquakes with magnitude up to Ms7.0 by using the satellite infrared remote sensing information. We used new types of data and method to extract the useful anomaly information. Based on the analyses of 8 earthquakes, we got the results as follows. (1) There are significant thermal radiation anomalies before and after earthquakes for all cases. The overall performance of anomalies includes two main stages: expanding first and narrowing later. We easily extracted and identified such seismic anomalies by method of “time-frequency relative power spectrum.” (2) There exist evident and different characteristic periods and magnitudes of thermal abnormal radiation for each case. (3) Thermal radiation anomalies are closely related to the geological structure. (4) Thermal radiation has obvious characteristics in abnormal duration, range, and morphology. In summary, we should be sure that earthquake thermal infrared anomalies as useful earthquake precursor can be used in earthquake prediction and forecasting. PMID:24222728

  19. Thermal infrared anomalies of several strong earthquakes.

    PubMed

    Wei, Congxin; Zhang, Yuansheng; Guo, Xiao; Hui, Shaoxing; Qin, Manzhong; Zhang, Ying

    2013-01-01

    In the history of earthquake thermal infrared research, it is undeniable that before and after strong earthquakes there are significant thermal infrared anomalies which have been interpreted as preseismic precursor in earthquake prediction and forecasting. In this paper, we studied the characteristics of thermal radiation observed before and after the 8 great earthquakes with magnitude up to Ms7.0 by using the satellite infrared remote sensing information. We used new types of data and method to extract the useful anomaly information. Based on the analyses of 8 earthquakes, we got the results as follows. (1) There are significant thermal radiation anomalies before and after earthquakes for all cases. The overall performance of anomalies includes two main stages: expanding first and narrowing later. We easily extracted and identified such seismic anomalies by method of "time-frequency relative power spectrum." (2) There exist evident and different characteristic periods and magnitudes of thermal abnormal radiation for each case. (3) Thermal radiation anomalies are closely related to the geological structure. (4) Thermal radiation has obvious characteristics in abnormal duration, range, and morphology. In summary, we should be sure that earthquake thermal infrared anomalies as useful earthquake precursor can be used in earthquake prediction and forecasting.

  20. Smoking prevalence increases following Canterbury earthquakes.

    PubMed

    Erskine, Nick; Daley, Vivien; Stevenson, Sue; Rhodes, Bronwen; Beckert, Lutz

    2013-01-01

    A magnitude 7.1 earthquake hit Canterbury in September 2010. This earthquake and associated aftershocks took the lives of 185 people and drastically changed residents' living, working, and social conditions. To explore the impact of the earthquakes on smoking status and levels of tobacco consumption in the residents of Christchurch. Semistructured interviews were carried out in two city malls and the central bus exchange 15 months after the first earthquake. A total of 1001 people were interviewed. In August 2010, prior to any earthquake, 409 (41%) participants had never smoked, 273 (27%) were currently smoking, and 316 (32%) were ex-smokers. Since the September 2010 earthquake, 76 (24%) of the 316 ex-smokers had smoked at least one cigarette and 29 (38.2%) had smoked more than 100 cigarettes. Of the 273 participants who were current smokers in August 2010, 93 (34.1%) had increased consumption following the earthquake, 94 (34.4%) had not changed, and 86 (31.5%) had decreased their consumption. 53 (57%) of the 93 people whose consumption increased reported that the earthquake and subsequent lifestyle changes as a reason to increase smoking. 24% of ex-smokers resumed smoking following the earthquake, resulting in increased smoking prevalence. Tobacco consumption levels increased in around one-third of current smokers.

  1. Issues on the Japanese Earthquake Hazard Evaluation

    NASA Astrophysics Data System (ADS)

    Hashimoto, M.; Fukushima, Y.; Sagiya, T.

    2013-12-01

    The 2011 Great East Japan Earthquake forced the policy of counter-measurements to earthquake disasters, including earthquake hazard evaluations, to be changed in Japan. Before the March 11, Japanese earthquake hazard evaluation was based on the history of earthquakes that repeatedly occurs and the characteristic earthquake model. The source region of an earthquake was identified and its occurrence history was revealed. Then the conditional probability was estimated using the renewal model. However, the Japanese authorities changed the policy after the megathrust earthquake in 2011 such that the largest earthquake in a specific seismic zone should be assumed on the basis of available scientific knowledge. According to this policy, three important reports were issued during these two years. First, the Central Disaster Management Council issued a new estimate of damages by a hypothetical Mw9 earthquake along the Nankai trough during 2011 and 2012. The model predicts a 34 m high tsunami on the southern Shikoku coast and intensity 6 or higher on the JMA scale in most area of Southwest Japan as the maximum. Next, the Earthquake Research Council revised the long-term earthquake hazard evaluation of earthquakes along the Nankai trough in May 2013, which discarded the characteristic earthquake model and put much emphasis on the diversity of earthquakes. The so-called 'Tokai' earthquake was negated in this evaluation. Finally, another report by the CDMC concluded that, with the current knowledge, it is hard to predict the occurrence of large earthquakes along the Nankai trough using the present techniques, based on the diversity of earthquake phenomena. These reports created sensations throughout the country and local governments are struggling to prepare counter-measurements. These reports commented on large uncertainty in their evaluation near their ends, but are these messages transmitted properly to the public? Earthquake scientists, including authors, are involved in

  2. Methodology to determine the parameters of historical earthquakes in China

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Lin, Guoliang; Zhang, Zhe

    2017-12-01

    China is one of the countries with the longest cultural tradition. Meanwhile, China has been suffering very heavy earthquake disasters; so, there are abundant earthquake recordings. In this paper, we try to sketch out historical earthquake sources and research achievements in China. We will introduce some basic information about the collections of historical earthquake sources, establishing intensity scale and the editions of historical earthquake catalogues. Spatial-temporal and magnitude distributions of historical earthquake are analyzed briefly. Besides traditional methods, we also illustrate a new approach to amend the parameters of historical earthquakes or even identify candidate zones for large historical or palaeo-earthquakes. In the new method, a relationship between instrumentally recorded small earthquakes and strong historical earthquakes is built up. Abundant historical earthquake sources and the achievements of historical earthquake research in China are of valuable cultural heritage in the world.

  3. 75 FR 8042 - Advisory Committee on Earthquake Hazards Reduction Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-23

    ... Earthquake Hazards Reduction Meeting AGENCY: National Institute of Standards and Technology, Department of Commerce. ACTION: Notice of open meeting. SUMMARY: The Advisory Committee on Earthquake Hazards Reduction.... FOR FURTHER INFORMATION CONTACT: Dr. Jack Hayes, National Earthquake Hazards Reduction Program...

  4. 75 FR 18787 - Advisory Committee on Earthquake Hazards Reduction Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-13

    ... Earthquake Hazards Reduction Meeting AGENCY: National Institute of Standards and Technology, Department of Commerce. ACTION: Notice of open meeting. SUMMARY: The Advisory Committee on Earthquake Hazards Reduction... sent to National Earthquake Hazards Reduction Program Director, National Institute of Standards and...

  5. Social Media as Seismic Networks for the Earthquake Damage Assessment

    NASA Astrophysics Data System (ADS)

    Meletti, C.; Cresci, S.; La Polla, M. N.; Marchetti, A.; Tesconi, M.

    2014-12-01

    The growing popularity of online platforms, based on user-generated content, is gradually creating a digital world that mirrors the physical world. In the paradigm of crowdsensing, the crowd becomes a distributed network of sensors that allows us to understand real life events at a quasi-real-time rate. The SoS-Social Sensing project [http://socialsensing.it/] exploits the opportunistic crowdsensing, involving users in the sensing process in a minimal way, for social media emergency management purposes in order to obtain a very fast, but still reliable, detection of emergency dimension to face. First of all we designed and implemented a decision support system for the detection and the damage assessment of earthquakes. Our system exploits the messages shared in real-time on Twitter. In the detection phase, data mining and natural language processing techniques are firstly adopted to select meaningful and comprehensive sets of tweets. Then we applied a burst detection algorithm in order to promptly identify outbreaking seismic events. Using georeferenced tweets and reported locality names, a rough epicentral determination is also possible. The results, compared to Italian INGV official reports, show that the system is able to detect, within seconds, events of a magnitude in the region of 3.5 with a precision of 75% and a recall of 81,82%. We then focused our attention on damage assessment phase. We investigated the possibility to exploit social media data to estimate earthquake intensity. We designed a set of predictive linear models and evaluated their ability to map the intensity of worldwide earthquakes. The models build on a dataset of almost 5 million tweets exploited to compute our earthquake features, and more than 7,000 globally distributed earthquakes data, acquired in a semi-automatic way from USGS, serving as ground truth. We extracted 45 distinct features falling into four categories: profile, tweet, time and linguistic. We run diagnostic tests and

  6. Revisiting the 1912 Murefet, Turkey earthquake and tsunami

    NASA Astrophysics Data System (ADS)

    Baptista, M.; Aksoy, M. M.; Ferreira, H.; Ucarkus, G.; Meghraoui, M.; Çakir, Z.

    2012-12-01

    The 9 August 1912 Mürefte Earthquake M 7.4 is one of the largest destructive earthquakes of the 20th century, in the Balkan region. The tremor struck at 03:30 a.m. and was felt in a wide region including Greece and Bulgaria. The damage was localized in the western part of the Sea of Marmara, between Tekirdag and Çanakkale with maximum intenstiy IX-X MSK near the Mürefte village. The damage killed 2800 and injured 7000 people. It totally destroyed 12600 houses, damaged 12100 beyond repair and caused serious damage to another 15,400. The earthquake occurred on the westernmost segment of the North Anatolian Fault (NAF), limited by the Marmara Sea and the Aegean Sea on both ends. The event was accompanied with major surface faulting and co-seismic slip all along the on land and offshore sections. Up to date several faulting scenarios were proposed for this event claiming surface ruptures ranging from 50- 150 km. The tsunami reports of this event are scarce Contemporary accounts reported several onshore and offshore natural events that can be related to a tsunami caused by submarine surface faulting. Receding of the sea and inundations were observed along the northern shores of the Sea of Marmara. Besides, most of the coastal area of the Strait of the Dardanelles (Çanakkale) experienced flooding. Strong sea waves hit the northern coasts of Hayirsiz Ada and at Yesilköy (near Istanbul) a rowing-boat has been lifted up to a height of 2.7 m. In this study we present a summary of the tsunami observations and perform tsunami numerical simulations using a nonlinear shallow water code (NSLW7) that uses an explicit leap-frog finite difference scheme to solve the non-linear shallow water equations and high resolution DEM (Digital Earth Model) including bathymetry and topography in order to compute inundation. The initial condition of the tsunami propagation model is the static vertical displacement of the ocean floor due to the submarine earthquake that is computed Mansinha

  7. The rupture process of the Manjil, Iran earthquake of 20 june 1990 and implications for intraplate strike-slip earthquakes

    USGS Publications Warehouse

    Choy, G.L.; Zednik, J.

    1997-01-01

    In terms of seismically radiated energy or moment release, the earthquake of 20 January 1990 in the Manjil Basin-Alborz Mountain region of Iran is the second largest strike-slip earthquake to have occurred in an intracontinental setting in the past decade. It caused enormous loss of life and the virtual destruction of several cities. Despite a very large meizoseismal area, the identification of the causative faults has been hampered by the lack of reliable earthquake locations and conflicting field reports of surface displacement. Using broadband data from global networks of digitally recording seismographs, we analyse broadband seismic waveforms to derive characteristics of the rupture process. Complexities in waveforms generated by the earthquake indicate that the main shock consisted of a tiny precursory subevent followed in the next 20 seconds by a series of four major subevents with depths ranging from 10 to 15 km. The focal mechanisms of the major subevents, which are predominantly strike-slip, have a common nodal plane striking about 285??-295??. Based on the coincidence of this strike with the dominant tectonic fabric of the region we presume that the EW striking planes are the fault planes. The first major subevent nucleated slightly south of the initial precursor. The second subevent occurred northwest of the initial precursor. The last two subevents moved progressively southeastward of the first subevent in a direction collinear with the predominant strike of the fault planes. The offsets in the relative locations and the temporal delays of the rupture subevents indicate heterogeneous distribution of fracture strength and the involvement of multiple faults. The spatial distribution of teleseismic aftershocks, which at first appears uncorrelated with meizoseismal contours, can be decomposed into stages. The initial activity, being within and on the periphery of the rupture zone, correlates in shape and length with meizoseismal lines. In the second stage

  8. Scanning for Digitization Projects

    ERIC Educational Resources Information Center

    Wentzel, Larry

    2007-01-01

    Librarians and archivists find themselves facing the prospect of digitization. Everyone is doing it, everyone needs it. Discussions rage nationally and internationally concerning what to digitize and the best means to present and retain digital objects. Digitization is the act of making something digital, expressing a physical object "in numerical…

  9. Remotely triggered earthquakes following moderate main shocks

    USGS Publications Warehouse

    Hough, S.E.

    2007-01-01

    Since 1992, remotely triggered earthquakes have been identified following large (M > 7) earthquakes in California as well as in other regions. These events, which occur at much greater distances than classic aftershocks, occur predominantly in active geothermal or volcanic regions, leading to theories that the earthquakes are triggered when passing seismic waves cause disruptions in magmatic or other fluid systems. In this paper, I focus on observations of remotely triggered earthquakes following moderate main shocks in diverse tectonic settings. I summarize evidence that remotely triggered earthquakes occur commonly in mid-continent and collisional zones. This evidence is derived from analysis of both historic earthquake sequences and from instrumentally recorded M5-6 earthquakes in eastern Canada. The latter analysis suggests that, while remotely triggered earthquakes do not occur pervasively following moderate earthquakes in eastern North America, a low level of triggering often does occur at distances beyond conventional aftershock zones. The inferred triggered events occur at the distances at which SmS waves are known to significantly increase ground motions. A similar result was found for 28 recent M5.3-7.1 earthquakes in California. In California, seismicity is found to increase on average to a distance of at least 200 km following moderate main shocks. This supports the conclusion that, even at distances of ???100 km, dynamic stress changes control the occurrence of triggered events. There are two explanations that can account for the occurrence of remotely triggered earthquakes in intraplate settings: (1) they occur at local zones of weakness, or (2) they occur in zones of local stress concentration. ?? 2007 The Geological Society of America.

  10. Seismicity map tools for earthquake studies

    NASA Astrophysics Data System (ADS)

    Boucouvalas, Anthony; Kaskebes, Athanasios; Tselikas, Nikos

    2014-05-01

    We report on the development of new and online set of tools for use within Google Maps, for earthquake research. We demonstrate this server based and online platform (developped with PHP, Javascript, MySQL) with the new tools using a database system with earthquake data. The platform allows us to carry out statistical and deterministic analysis on earthquake data use of Google Maps and plot various seismicity graphs. The tool box has been extended to draw on the map line segments, multiple straight lines horizontally and vertically as well as multiple circles, including geodesic lines. The application is demonstrated using localized seismic data from the geographic region of Greece as well as other global earthquake data. The application also offers regional segmentation (NxN) which allows the studying earthquake clustering, and earthquake cluster shift within the segments in space. The platform offers many filters such for plotting selected magnitude ranges or time periods. The plotting facility allows statistically based plots such as cumulative earthquake magnitude plots and earthquake magnitude histograms, calculation of 'b' etc. What is novel for the platform is the additional deterministic tools. Using the newly developed horizontal and vertical line and circle tools we have studied the spatial distribution trends of many earthquakes and we here show for the first time the link between Fibonacci Numbers and spatiotemporal location of some earthquakes. The new tools are valuable for examining visualizing trends in earthquake research as it allows calculation of statistics as well as deterministic precursors. We plan to show many new results based on our newly developed platform.

  11. Spatial Evaluation and Verification of Earthquake Simulators

    NASA Astrophysics Data System (ADS)

    Wilson, John Max; Yoder, Mark R.; Rundle, John B.; Turcotte, Donald L.; Schultz, Kasey W.

    2017-06-01

    In this paper, we address the problem of verifying earthquake simulators with observed data. Earthquake simulators are a class of computational simulations which attempt to mirror the topological complexity of fault systems on which earthquakes occur. In addition, the physics of friction and elastic interactions between fault elements are included in these simulations. Simulation parameters are adjusted so that natural earthquake sequences are matched in their scaling properties. Physically based earthquake simulators can generate many thousands of years of simulated seismicity, allowing for a robust capture of the statistical properties of large, damaging earthquakes that have long recurrence time scales. Verification of simulations against current observed earthquake seismicity is necessary, and following past simulator and forecast model verification methods, we approach the challenges in spatial forecast verification to simulators; namely, that simulator outputs are confined to the modeled faults, while observed earthquake epicenters often occur off of known faults. We present two methods for addressing this discrepancy: a simplistic approach whereby observed earthquakes are shifted to the nearest fault element and a smoothing method based on the power laws of the epidemic-type aftershock (ETAS) model, which distributes the seismicity of each simulated earthquake over the entire test region at a decaying rate with epicentral distance. To test these methods, a receiver operating characteristic plot was produced by comparing the rate maps to observed m>6.0 earthquakes in California since 1980. We found that the nearest-neighbor mapping produced poor forecasts, while the ETAS power-law method produced rate maps that agreed reasonably well with observations.

  12. Intraplate triggered earthquakes: Observations and interpretation

    USGS Publications Warehouse

    Hough, S.E.; Seeber, L.; Armbruster, J.G.

    2003-01-01

    We present evidence that at least two of the three 1811-1812 New Madrid, central United States, mainshocks and the 1886 Charleston, South Carolina, earthquake triggered earthquakes at regional distances. In addition to previously published evidence for triggered earthquakes in the northern Kentucky/southern Ohio region in 1812, we present evidence suggesting that triggered events might have occurred in the Wabash Valley, to the south of the New Madrid Seismic Zone, and near Charleston, South Carolina. We also discuss evidence that earthquakes might have been triggered in northern Kentucky within seconds of the passage of surface waves from the 23 January 1812 New Madrid mainshock. After the 1886 Charleston earthquake, accounts suggest that triggered events occurred near Moodus, Connecticut, and in southern Indiana. Notwithstanding the uncertainty associated with analysis of historical accounts, there is evidence that at least three out of the four known Mw 7 earthquakes in the central and eastern United States seem to have triggered earthquakes at distances beyond the typically assumed aftershock zone of 1-2 mainshock fault lengths. We explore the possibility that remotely triggered earthquakes might be common in low-strain-rate regions. We suggest that in a low-strain-rate environment, permanent, nonelastic deformation might play a more important role in stress accumulation than it does in interplate crust. Using a simple model incorporating elastic and anelastic strain release, we show that, for realistic parameter values, faults in intraplate crust remain close to their failure stress for a longer part of the earthquake cycle than do faults in high-strain-rate regions. Our results further suggest that remotely triggered earthquakes occur preferentially in regions of recent and/or future seismic activity, which suggests that faults are at a critical stress state in only some areas. Remotely triggered earthquakes may thus serve as beacons that identify regions of

  13. Surface rupture and slip variation induced by the 2010 El Mayor-Cucapah earthquake, Baja California, quantified using COSI-Corr analysis on pre- and post-earthquake LiDAR acquisitions

    NASA Astrophysics Data System (ADS)

    Leprince, S.; Hudnut, K. W.; Akciz, S. O.; Hinojosa-Corona, A.; Fletcher, J. M.

    2011-12-01

    One-hundred and three years after the publication of the Lawson report on the Great 1906 earthquake, accurate documentation of surface deformation along the entire length of an earthquake is still challenging. Analysis of pre- and post-earthquake topographic data provides an opportunity to deliver the full 3D displacement field of the ground's surface. However, direct differencing of a pre- and post-earthquake digital topography model (DEM) generally leads to biased estimation of the vertical component of the deformation. Indeed, if the earthquake also produced significant horizontal motion, or if the pre- and post-earthquake DEM acquisitions exhibit non-negligible horizontal mis-registration, then the vertical offset measured by direct differencing will be biased by the local topography gradient. To overcome this limitation, we use the COSI-Corr sub-pixel correlation algorithm to estimate the relative horizontal offset between the pre- and post- 2010 El Mayor - Cucapah earthquake high resolution LiDAR acquisitions. Compensating for the horizontal offset between the two LiDAR acquisitions allows us to estimate unbiased measurements of the vertical component of the surface fault rupture induced by the El Mayor-Cucapah earthquake. We will also show the limitations of the available data set, such as aircraft jitter artifacts, which impaired accurate measurements of the horizontal component of the surface deformation. This analysis shows an unprecedented view of the complete vertical slip component of the rupture induced by the Mw 7.2 2010 El Mayor-Cucapah earthquake, sampled at every 5 m, over a length of about 100 km, and with a vertical accuracy of a few centimeters. Using sampling bins as narrow as 150 m and 1.5 km long, variations in the vertical component of an oblique slip earthquake are presented, with breaks along multiple fault-strands showing opposite dip directions and diffuse boundaries. With the availability of high precision pre- and post-earthquake data

  14. Earthquake catalog for estimation of maximum earthquake magnitude, Central and Eastern United States: Part B, historical earthquakes

    USGS Publications Warehouse

    Wheeler, Russell L.

    2014-01-01

    Computation of probabilistic earthquake hazard requires an estimate of Mmax: the moment magnitude of the largest earthquake that is thought to be possible within a specified geographic region. The region specified in this report is the Central and Eastern United States and adjacent Canada. Parts A and B of this report describe the construction of a global catalog of moderate to large earthquakes that occurred worldwide in tectonic analogs of the Central and Eastern United States. Examination of histograms of the magnitudes of these earthquakes allows estimation of Central and Eastern United States Mmax. The catalog and Mmax estimates derived from it are used in the 2014 edition of the U.S. Geological Survey national seismic-hazard maps. Part A deals with prehistoric earthquakes, and this part deals with historical events.

  15. GEM - The Global Earthquake Model

    NASA Astrophysics Data System (ADS)

    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

  16. Results of the Regional Earthquake Likelihood Models (RELM) test of earthquake forecasts in California.

    PubMed

    Lee, Ya-Ting; Turcotte, Donald L; Holliday, James R; Sachs, Michael K; Rundle, John B; Chen, Chien-Chih; Tiampo, Kristy F

    2011-10-04

    The Regional Earthquake Likelihood Models (RELM) test of earthquake forecasts in California was the first competitive evaluation of forecasts of future earthquake occurrence. Participants submitted expected probabilities of occurrence of M ≥ 4.95 earthquakes in 0.1° × 0.1° cells for the period 1 January 1, 2006, to December 31, 2010. Probabilities were submitted for 7,682 cells in California and adjacent regions. During this period, 31 M ≥ 4.95 earthquakes occurred in the test region. These earthquakes occurred in 22 test cells. This seismic activity was dominated by earthquakes associated with the M = 7.2, April 4, 2010, El Mayor-Cucapah earthquake in northern Mexico. This earthquake occurred in the test region, and 16 of the other 30 earthquakes in the test region could be associated with it. Nine complete forecasts were submitted by six participants. In this paper, we present the forecasts in a way that allows the reader to evaluate which forecast is the most "successful" in terms of the locations of future earthquakes. We conclude that the RELM test was a success and suggest ways in which the results can be used to improve future forecasts.

  17. Earthquake and tsunami forecasts: Relation of slow slip events to subsequent earthquake rupture

    PubMed Central

    Dixon, Timothy H.; Jiang, Yan; Malservisi, Rocco; McCaffrey, Robert; Voss, Nicholas; Protti, Marino; Gonzalez, Victor

    2014-01-01

    The 5 September 2012 Mw 7.6 earthquake on the Costa Rica subduction plate boundary followed a 62-y interseismic period. High-precision GPS recorded numerous slow slip events (SSEs) in the decade leading up to the earthquake, both up-dip and down-dip of seismic rupture. Deeper SSEs were larger than shallower ones and, if characteristic of the interseismic period, release most locking down-dip of the earthquake, limiting down-dip rupture and earthquake magnitude. Shallower SSEs were smaller, accounting for some but not all interseismic locking. One SSE occurred several months before the earthquake, but changes in Mohr–Coulomb failure stress were probably too small to trigger the earthquake. Because many SSEs have occurred without subsequent rupture, their individual predictive value is limited, but taken together they released a significant amount of accumulated interseismic strain before the earthquake, effectively defining the area of subsequent seismic rupture (rupture did not occur where slow slip was common). Because earthquake magnitude depends on rupture area, this has important implications for earthquake hazard assessment. Specifically, if this behavior is representative of future earthquake cycles and other subduction zones, it implies that monitoring SSEs, including shallow up-dip events that lie offshore, could lead to accurate forecasts of earthquake magnitude and tsunami potential. PMID:25404327

  18. Earthquake and tsunami forecasts: relation of slow slip events to subsequent earthquake rupture.

    PubMed

    Dixon, Timothy H; Jiang, Yan; Malservisi, Rocco; McCaffrey, Robert; Voss, Nicholas; Protti, Marino; Gonzalez, Victor

    2014-12-02

    The 5 September 2012 M(w) 7.6 earthquake on the Costa Rica subduction plate boundary followed a 62-y interseismic period. High-precision GPS recorded numerous slow slip events (SSEs) in the decade leading up to the earthquake, both up-dip and down-dip of seismic rupture. Deeper SSEs were larger than shallower ones and, if characteristic of the interseismic period, release most locking down-dip of the earthquake, limiting down-dip rupture and earthquake magnitude. Shallower SSEs were smaller, accounting for some but not all interseismic locking. One SSE occurred several months before the earthquake, but changes in Mohr-Coulomb failure stress were probably too small to trigger the earthquake. Because many SSEs have occurred without subsequent rupture, their individual predictive value is limited, but taken together they released a significant amount of accumulated interseismic strain before the earthquake, effectively defining the area of subsequent seismic rupture (rupture did not occur where slow slip was common). Because earthquake magnitude depends on rupture area, this has important implications for earthquake hazard assessment. Specifically, if this behavior is representative of future earthquake cycles and other subduction zones, it implies that monitoring SSEs, including shallow up-dip events that lie offshore, could lead to accurate forecasts of earthquake magnitude and tsunami potential.

  19. Results of the Regional Earthquake Likelihood Models (RELM) test of earthquake forecasts in California

    PubMed Central

    Lee, Ya-Ting; Turcotte, Donald L.; Holliday, James R.; Sachs, Michael K.; Rundle, John B.; Chen, Chien-Chih; Tiampo, Kristy F.

    2011-01-01

    The Regional Earthquake Likelihood Models (RELM) test of earthquake forecasts in California was the first competitive evaluation of forecasts of future earthquake occurrence. Participants submitted expected probabilities of occurrence of M≥4.95 earthquakes in 0.1° × 0.1° cells for the period 1 January 1, 2006, to December 31, 2010. Probabilities were submitted for 7,682 cells in California and adjacent regions. During this period, 31 M≥4.95 earthquakes occurred in the test region. These earthquakes occurred in 22 test cells. This seismic activity was dominated by earthquakes associated with the M = 7.2, April 4, 2010, El Mayor–Cucapah earthquake in northern Mexico. This earthquake occurred in the test region, and 16 of the other 30 earthquakes in the test region could be associated with it. Nine complete forecasts were submitted by six participants. In this paper, we present the forecasts in a way that allows the reader to evaluate which forecast is the most “successful” in terms of the locations of future earthquakes. We conclude that the RELM test was a success and suggest ways in which the results can be used to improve future forecasts. PMID:21949355

  20. Earthquake potential revealed by tidal influence on earthquake size-frequency statistics

    NASA Astrophysics Data System (ADS)

    Ide, Satoshi; Yabe, Suguru; Tanaka, Yoshiyuki

    2016-11-01

    The possibility that tidal stress can trigger earthquakes is long debated. In particular, a clear causal relationship between small earthquakes and the phase of tidal stress is elusive. However, tectonic tremors deep within subduction zones are highly sensitive to tidal stress levels, with tremor rate increasing at an exponential rate with rising tidal stress. Thus, slow deformation and the possibility of earthquakes at subduction plate boundaries may be enhanced during periods of large tidal stress. Here we calculate the tidal stress history, and specifically the amplitude of tidal stress, on a fault plane in the two weeks before large earthquakes globally, based on data from the global, Japanese, and Californian earthquake catalogues. We find that very large earthquakes, including the 2004 Sumatran, 2010 Maule earthquake in Chile and the 2011 Tohoku-Oki earthquake in Japan, tend to occur near the time of maximum tidal stress amplitude. This tendency is not obvious for small earthquakes. However, we also find that the fraction of large earthquakes increases (the b-value of the Gutenberg-Richter relation decreases) as the amplitude of tidal shear stress increases. The relationship is also reasonable, considering the well-known relationship between stress and the b-value. This suggests that the probability of a tiny rock failure expanding to a gigantic rupture increases with increasing tidal stress levels. We conclude that large earthquakes are more probable during periods of high tidal stress.

  1. Putting down roots in earthquake country-Your handbook for earthquakes in the Central United States

    USGS Publications Warehouse

    Contributors: Dart, Richard; McCarthy, Jill; McCallister, Natasha; Williams, Robert A.

    2011-01-01

    This handbook provides information to residents of the Central United States about the threat of earthquakes in that area, particularly along the New Madrid seismic zone, and explains how to prepare for, survive, and recover from such events. It explains the need for concern about earthquakes for those residents and describes what one can expect during and after an earthquake. Much is known about the threat of earthquakes in the Central United States, including where they are likely to occur and what can be done to reduce losses from future earthquakes, but not enough has been done to prepare for future earthquakes. The handbook describes such preparations that can be taken by individual residents before an earthquake to be safe and protect property.

  2. Foreshock occurrence before large earthquakes

    USGS Publications Warehouse

    Reasenberg, P.A.

    1999-01-01

    Rates of foreshock occurrence involving shallow M ??? 6 and M ??? 7 mainshocks and M ??? 5 foreshocks were measured in two worldwide catalogs over ???20-year intervals. The overall rates observed are similar to ones measured in previous worldwide and regional studies when they are normalized for the ranges of magnitude difference they each span. The observed worldwide rates were compared to a generic model of earthquake clustering based on patterns of small and moderate aftershocks in California. The aftershock model was extended to the case of moderate foreshocks preceding large mainshocks. Overall, the observed worldwide foreshock rates exceed the extended California generic model by a factor of ???2. Significant differences in foreshock rate were found among subsets of earthquakes defined by their focal mechanism and tectonic region, with the rate before thrust events higher and the rate before strike-slip events lower than the worldwide average. Among the thrust events, a large majority, composed of events located in shallow subduction zones, had a high foreshock rate, while a minority, located in continental thrust belts, had a low rate. These differences may explain why previous surveys have found low foreshock rates among thrust events in California (especially southern California), while the worldwide observations suggests the opposite: California, lacking an active subduction zone in most of its territory, and including a region of mountain-building thrusts in the south, reflects the low rate apparently typical for continental thrusts, while the worldwide observations, dominated by shallow subduction zone events, are foreshock-rich. If this is so, then the California generic model may significantly underestimate the conditional probability for a very large (M ??? 8) earthquake following a potential (M ??? 7) foreshock in Cascadia. The magnitude differences among the identified foreshock-mainshock pairs in the Harvard catalog are consistent with a uniform

  3. Digital Avionics

    NASA Technical Reports Server (NTRS)

    Koelbl, Terry G.; Ponchak, Denise; Lamarche, Teresa

    2003-01-01

    Digital Avionics activities played an important role in the advancements made in civil aviation, military systems, and space applications. This document profiles advances made in each of these areas by the aerospace industry, NASA centers, and the U.S. military. Emerging communication technologies covered in this document include Internet connectivity onboard aircraft, wireless broadband communication for aircraft, and a mobile router for aircraft to communicate in multiple communication networks over the course of a flight. Military technologies covered in this document include avionics for unmanned combat air vehicles and microsatellites, and head-up displays. Other technologies covered in this document include an electronic flight bag for the Boeing 777, and surveillance systems for managing airport operations.

  4. Digital structural

    USGS Publications Warehouse

    Dohm, J.M.; Anderson, R.C.; Tanaka, K.L.

    1998-01-01

    Magmatic and tectonic activity have both contributed significantly to the surface geology of Mars. Digital structural mapping techniques have now been used to classify and date centers of tectonic activity in the western equatorial region. For example, our results show a center of tectonic activity at Valles Marineris, which may be associated with uplift caused by intrusion. Such evidence may help explain, in part, the development of the large troughs and associated outflow channels and chaotic terrain. We also find a local centre of tectonic activity near the source region of Warrego Valles. Here, we suggest that the valley system may have resulted largely from intrusive-related hydrothermal activity. We hope that this work, together with the current Mars Global Surveyor mission, will lead to a better understanding of the geological processes that shaped the Martian surface.

  5. Digital Avionics

    NASA Technical Reports Server (NTRS)

    Koelbl, Terry G.; Ponchak, Denise; Lamarche, Teresa

    2002-01-01

    The field of digital avionics experienced another year of important advances in civil aviation, military systems, and space applications. As a result of the events of 9/11/2001, NASA has pursued activities to apply its aerospace technologies toward improved aviation security. Both NASA Glenn Research Center and Langley Research Center have performed flight research demonstrations using advanced datalink concepts to transmit live pictures from inside a jetliner, and to downlink the contents of the plane's 'black box' recorder in real time. The U.S. Navy and General Electric demonstrated survivable engine control (SEC) algorithms during engine ground tests at the Weapons Survivability Laboratory at China Lake. The scientists at Boeing Satellite Systems advanced the field of stellar inertial technology with the development of a new method for positioning optical star trackers on satellites.

  6. The 2010 Haiti earthquake response.

    PubMed

    Raviola, Giuseppe; Severe, Jennifer; Therosme, Tatiana; Oswald, Cate; Belkin, Gary; Eustache, Eddy

    2013-09-01

    This article presents an overview of the mental health response to the 2010 Haiti earthquake. Discussion includes consideration of complexities that relate to emergency response, mental health and psychosocial response in disasters, long-term planning of systems of care, and the development of safe, effective, and culturally sound mental health services in the Haitian context. This information will be of value to mental health professionals and policy specialists interested in mental health in Haiti, and in the delivery of mental health services in particularly resource-limited contexts in the setting of disasters. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. The Maupin, Oregon Earthquake Swarm

    NASA Astrophysics Data System (ADS)

    Braunmiller, J.; Williams, M.; Trehu, A. M.; Nabelek, J.

    2008-12-01

    The area near Maupin, Oregon has experienced over 300 earthquakes since December 2006. The events, located by the Pacific Northwest Seismic Network (PNSN), occurred ~10 km SE of the town in central Oregon and ~50 km E-SE of Mount Hood. The temporal event pattern and lack of a distinct main shock are characteristic of an earthquake swarm with the event-size distribution indicating a low b-value similar to other non-volcanic swarms. Locations show a NW-SE trending, ~4x3 km cluster at apparent depths of 12-24 km. The largest events (Mw=3.8 and 3.9) on March 1, 2007 and July 14, 2008 occurred more than one year apart; 11 other events had a magnitude of 3 or greater. The larger events were felt locally. During the first 14 months EarthScope USArray seismic stations surrounded the swarm, providing a unique high-quality dataset. Waveform similarity at the closest USArray site G06A indicates hypocenters are much tighter than suggested by the PNSN distribution. Moment tensor inversion reveals nearly identical double- couple strike-slip mechanisms on a plane striking ~15° NW for the three largest 2007 events and the July 2008 event. The April 2008 Mw=3.3 event is rotated ~10° clockwise consistent with slight changes of G06A three-component waveforms relative to the other events. Preferred centroid depths are in the 15-20 km range. Historically, seismicity in the Pacific Northwest east of the Cascades is characterized by sporadic bursts of clustered seismicity with occasional M=6 earthquakes. The largest instrumentally recorded earthquake near Maupin (Mw=4.6) occurred 1976. An earlier swarm was observed 1987, but since then only ~2 events/yr occurred until the current swarm. In spite of recurrent seismicity, exposed surface rocks near Maupin are undeformed lava flows of the Columbia River Basalt Group and older John Day volcanics. The geologic map of Oregon shows a NW-trending dip slip fault near the epicenter area, inconsistent with moment tensor solutions. The cause for

  8. Bayesian exploration of recent Chilean earthquakes

    NASA Astrophysics Data System (ADS)

    Duputel, Zacharie; Jiang, Junle; Jolivet, Romain; Simons, Mark; Rivera, Luis; Ampuero, Jean-Paul; Liang, Cunren; Agram, Piyush; Owen, Susan; Ortega, Francisco; Minson, Sarah

    2016-04-01

    The South-American subduction zone is an exceptional natural laboratory for investigating the behavior of large faults over the earthquake cycle. It is also a playground to develop novel modeling techniques combining different datasets. Coastal Chile was impacted by two major earthquakes in the last two years: the 2015 M 8.3 Illapel earthquake in central Chile and the 2014 M 8.1 Iquique earthquake that ruptured the central portion of the 1877 seismic gap in northern Chile. To gain better understanding of the distribution of co-seismic slip for those two earthquakes, we derive joint kinematic finite fault models using a combination of static GPS offsets, radar interferograms, tsunami measurements, high-rate GPS waveforms and strong motion data. Our modeling approach follows a Bayesian formulation devoid of a priori smoothing thereby allowing us to maximize spatial resolution of the inferred family of models. The adopted approach also attempts to account for major sources of uncertainty in the Green's functions. The results reveal different rupture behaviors for the 2014 Iquique and 2015 Illapel earthquakes. The 2014 Iquique earthquake involved a sharp slip zone and did not rupture to the trench. The 2015 Illapel earthquake nucleated close to the coast and propagated toward the trench with significant slip apparently reaching the trench or at least very close to the trench. At the inherent resolution of our models, we also present the relationship of co-seismic models to the spatial distribution of foreshocks, aftershocks and fault coupling models.

  9. Scoring annual earthquake predictions in China

    NASA Astrophysics Data System (ADS)

    Zhuang, Jiancang; Jiang, Changsheng

    2012-02-01

    The Annual Consultation Meeting on Earthquake Tendency in China is held by the China Earthquake Administration (CEA) in order to provide one-year earthquake predictions over most China. In these predictions, regions of concern are denoted together with the corresponding magnitude range of the largest earthquake expected during the next year. Evaluating the performance of these earthquake predictions is rather difficult, especially for regions that are of no concern, because they are made on arbitrary regions with flexible magnitude ranges. In the present study, the gambling score is used to evaluate the performance of these earthquake predictions. Based on a reference model, this scoring method rewards successful predictions and penalizes failures according to the risk (probability of being failure) that the predictors have taken. Using the Poisson model, which is spatially inhomogeneous and temporally stationary, with the Gutenberg-Richter law for earthquake magnitudes as the reference model, we evaluate the CEA predictions based on 1) a partial score for evaluating whether issuing the alarmed regions is based on information that differs from the reference model (knowledge of average seismicity level) and 2) a complete score that evaluates whether the overall performance of the prediction is better than the reference model. The predictions made by the Annual Consultation Meetings on Earthquake Tendency from 1990 to 2003 are found to include significant precursory information, but the overall performance is close to that of the reference model.

  10. Earthquake hazards on the cascadia subduction zone.

    PubMed

    Heaton, T H; Hartzell, S H

    1987-04-10

    Large subduction earthquakes on the Cascadia subduction zone pose a potential seismic hazard. Very young oceanic lithosphere (10 million years old) is being subducted beneath North America at a rate of approximately 4 centimeters per year. The Cascadia subduction zone shares many characteristics with subduction zones in southern Chile, southwestern Japan, and Colombia, where comparably young oceanic lithosphere is also subducting. Very large subduction earthquakes, ranging in energy magnitude (M(w)) between 8 and 9.5, have occurred along these other subduction zones. If the Cascadia subduction zone is also storing elastic energy, a sequence of several great earthquakes (M(w) 8) or a giant earthquake (M(w) 9) would be necessary to fill this 1200-kilometer gap. The nature of strong ground motions recorded during subduction earthquakes of M(w) less than 8.2 is discussed. Strong ground motions from even larger earthquakes (M(w) up to 9.5) are estimated by simple simulations. If large subduction earthquakes occur in the Pacific Northwest, relatively strong shaking can be expected over a large region. Such earthquakes may also be accompanied by large local tsunamis.

  11. Earthquake Hazard Analysis Methods: A Review

    NASA Astrophysics Data System (ADS)

    Sari, A. M.; Fakhrurrozi, A.

    2018-02-01

    One of natural disasters that have significantly impacted on risks and damage is an earthquake. World countries such as China, Japan, and Indonesia are countries located on the active movement of continental plates with more frequent earthquake occurrence compared to other countries. Several methods of earthquake hazard analysis have been done, for example by analyzing seismic zone and earthquake hazard micro-zonation, by using Neo-Deterministic Seismic Hazard Analysis (N-DSHA) method, and by using Remote Sensing. In its application, it is necessary to review the effectiveness of each technique in advance. Considering the efficiency of time and the accuracy of data, remote sensing is used as a reference to the assess earthquake hazard accurately and quickly as it only takes a limited time required in the right decision-making shortly after the disaster. Exposed areas and possibly vulnerable areas due to earthquake hazards can be easily analyzed using remote sensing. Technological developments in remote sensing such as GeoEye-1 provide added value and excellence in the use of remote sensing as one of the methods in the assessment of earthquake risk and damage. Furthermore, the use of this technique is expected to be considered in designing policies for disaster management in particular and can reduce the risk of natural disasters such as earthquakes in Indonesia.

  12. How fault geometry controls earthquake magnitude

    NASA Astrophysics Data System (ADS)

    Bletery, Q.; Thomas, A.; Karlstrom, L.; Rempel, A. W.; Sladen, A.; De Barros, L.

    2016-12-01

    Recent large megathrust earthquakes, such as the Mw9.3 Sumatra-Andaman earthquake in 2004 and the Mw9.0 Tohoku-Oki earthquake in 2011, astonished the scientific community. The first event occurred in a relatively low-convergence-rate subduction zone where events of its size were unexpected. The second event involved 60 m of shallow slip in a region thought to be aseismicaly creeping and hence incapable of hosting very large magnitude earthquakes. These earthquakes highlight gaps in our understanding of mega-earthquake rupture processes and the factors controlling their global distribution. Here we show that gradients in dip angle exert a primary control on mega-earthquake occurrence. We calculate the curvature along the major subduction zones of the world and show that past mega-earthquakes occurred on flat (low-curvature) interfaces. A simplified analytic model demonstrates that shear strength heterogeneity increases with curvature. Stress loading on flat megathrusts is more homogeneous and hence more likely to be released simultaneously over large areas than on highly-curved faults. Therefore, the absence of asperities on large faults might counter-intuitively be a source of higher hazard.

  13. Interpreting the strongest deep earthquake ever observed

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2013-12-01

    Massive earthquakes that strike deep within the Earth may be more efficient at dissipating pent-up energy than similar quakes near the surface, according to new research by Wei et al. The authors analyzed the rupture of the most powerful deep earthquake ever recorded.

  14. 13 CFR 120.174 - Earthquake hazards.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Earthquake hazards. 120.174 Section 120.174 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION BUSINESS LOANS Policies Applying to All Business Loans Requirements Imposed Under Other Laws and Orders § 120.174 Earthquake...

  15. Napa Earthquake impact on water systems

    NASA Astrophysics Data System (ADS)

    Wang, J.

    2014-12-01

    South Napa earthquake occurred in Napa, California on August 24 at 3am, local time, and the magnitude is 6.0. The earthquake was the largest in SF Bay Area since the 1989 Loma Prieta earthquake. Economic loss topped $ 1 billion. Wine makers cleaning up and estimated the damage on tourism. Around 15,000 cases of lovely cabernet were pouring into the garden at the Hess Collection. Earthquake potentially raise water pollution risks, could cause water crisis. CA suffered water shortage recent years, and it could be helpful on how to prevent underground/surface water pollution from earthquake. This research gives a clear view on drinking water system in CA, pollution on river systems, as well as estimation on earthquake impact on water supply. The Sacramento-San Joaquin River delta (close to Napa), is the center of the state's water distribution system, delivering fresh water to more than 25 million residents and 3 million acres of farmland. Delta water conveyed through a network of levees is crucial to Southern California. The drought has significantly curtailed water export, and salt water intrusion reduced fresh water outflows. Strong shaking from a nearby earthquake can cause saturated, loose, sandy soils liquefaction, and could potentially damage major delta levee systems near Napa. Napa earthquake is a wake-up call for Southern California. It could potentially damage freshwater supply system.

  16. New ideas about the physics of earthquakes

    NASA Astrophysics Data System (ADS)

    Rundle, John B.; Klein, William

    1995-07-01

    It may be no exaggeration to claim that this most recent quaddrenium has seen more controversy and thus more progress in understanding the physics of earthquakes than any in recent memory. The most interesting development has clearly been the emergence of a large community of condensed matter physicists around the world who have begun working on the problem of earthquake physics. These scientists bring to the study of earthquakes an entirely new viewpoint, grounded in the physics of nucleation and critical phenomena in thermal, magnetic, and other systems. Moreover, a surprising technology transfer from geophysics to other fields has been made possible by the realization that models originally proposed to explain self-organization in earthquakes can also be used to explain similar processes in problems as disparate as brain dynamics in neurobiology (Hopfield, 1994), and charge density waves in solids (Brown and Gruner, 1994). An entirely new sub-discipline is emerging that is focused around the development and analysis of large scale numerical simulations of the dynamics of faults. At the same time, intriguing new laboratory and field data, together with insightful physical reasoning, has led to significant advances in our understanding of earthquake source physics. As a consequence, we can anticipate substantial improvement in our ability to understand the nature of earthquake occurrence. Moreover, while much research in the area of earthquake physics is fundamental in character, the results have many potential applications (Cornell et al., 1993) in the areas of earthquake risk and hazard analysis, and seismic zonation.

  17. Designing an Earthquake-Resistant Building

    ERIC Educational Resources Information Center

    English, Lyn D.; King, Donna T.

    2016-01-01

    How do cross-bracing, geometry, and base isolation help buildings withstand earthquakes? These important structural design features involve fundamental geometry that elementary school students can readily model and understand. The problem activity, Designing an Earthquake-Resistant Building, was undertaken by several classes of sixth- grade…

  18. Triggering of repeating earthquakes in central California

    USGS Publications Warehouse

    Wu, Chunquan; Gomberg, Joan; Ben-Naim, Eli; Johnson, Paul

    2014-01-01

    Dynamic stresses carried by transient seismic waves have been found capable of triggering earthquakes instantly in various tectonic settings. Delayed triggering may be even more common, but the mechanisms are not well understood. Catalogs of repeating earthquakes, earthquakes that recur repeatedly at the same location, provide ideal data sets to test the effects of transient dynamic perturbations on the timing of earthquake occurrence. Here we employ a catalog of 165 families containing ~2500 total repeating earthquakes to test whether dynamic perturbations from local, regional, and teleseismic earthquakes change recurrence intervals. The distance to the earthquake generating the perturbing waves is a proxy for the relative potential contributions of static and dynamic deformations, because static deformations decay more rapidly with distance. Clear changes followed the nearby 2004 Mw6 Parkfield earthquake, so we study only repeaters prior to its origin time. We apply a Monte Carlo approach to compare the observed number of shortened recurrence intervals following dynamic perturbations with the distribution of this number estimated for randomized perturbation times. We examine the comparison for a series of dynamic stress peak amplitude and distance thresholds. The results suggest a weak correlation between dynamic perturbations in excess of ~20 kPa and shortened recurrence intervals, for both nearby and remote perturbations.

  19. Inventory of landslides triggered by the 1994 Northridge, California earthquake

    USGS Publications Warehouse

    Harp, Edwin L.; Jibson, Randall W.

    1995-01-01

    The 17 January 1994 Northridge, California, earthquake (M=6.7) triggered more than 11,000 landslides over an area of about 10,000 km?. Most of the landslides were concentrated in a 1,000-km? area that includes the Santa Susana Mountains and the mountains north of the Santa Clara River valley. We mapped landslides triggered by the earthquake in the field and from 1:60,000-scale aerial photography provided by the U.S. Air Force and taken the morning of the earthquake; these were subsequently digitized and plotted in a GIS-based format, as shown on the accompanying maps (which also are accessible via Internet). Most of the triggered landslides were shallow (1-5 m), highly disrupted falls and slides in weakly cemented Tertiary to Pleistocene clastic sediment. Average volumes of these types of landslides were less than 1,000 m?, but many had volumes exceeding 100,000 m?. Many of the larger disrupted slides traveled more than 50 m, and a few moved as far as 200 m from the bases of steep parent slopes. Deeper ( >5 m) rotational slumps and block slides numbered in the hundreds, a few of which exceeded 100,000 m? in volume. The largest triggered landslide was a block slide having a volume of 8X10E06 m?. Triggered landslides damaged or destroyed dozens of homes, blocked roads, and damaged oil-field infrastructure. Analysis of landslide distribution with respect to variations in (1) landslide susceptibility and (2) strong shaking recorded by hundreds of instruments will form the basis of a seismic landslide hazard analysis of the Los Angeles area.

  20. Defining "Acceptable Risk" for Earthquakes Worldwide

    NASA Astrophysics Data System (ADS)

    Tucker, B.

    2001-05-01

    The greatest and most rapidly growing earthquake risk for mortality is in developing countries. Further, earthquake risk management actions of the last 50 years have reduced the average lethality of earthquakes in earthquake-threatened industrialized countries. (This is separate from the trend of the increasing fiscal cost of earthquakes there.) Despite these clear trends, every new earthquake in developing countries is described in the media as a "wake up" call, announcing the risk these countries face. GeoHazards International (GHI) works at both the community and the policy levels to try to reduce earthquake risk. GHI reduces death and injury by helping vulnerable communities recognize their risk and the methods to manage it, by raising awareness of its risk, building local institutions to manage that risk, and strengthening schools to protect and train the community's future generations. At the policy level, GHI, in collaboration with research partners, is examining whether "acceptance" of these large risks by people in these countries and by international aid and development organizations explains the lack of activity in reducing these risks. The goal of this pilot project - The Global Earthquake Safety Initiative (GESI) - is to develop and evaluate a means of measuring the risk and the effectiveness of risk mitigation actions in the world's largest, most vulnerable cities: in short, to develop an earthquake risk index. One application of this index is to compare the risk and the risk mitigation effort of "comparable" cities. By this means, Lima, for example, can compare the risk of its citizens dying due to earthquakes with the risk of citizens in Santiago and Guayaquil. The authorities of Delhi and Islamabad can compare the relative risk from earthquakes of their school children. This index can be used to measure the effectiveness of alternate mitigation projects, to set goals for mitigation projects, and to plot progress meeting those goals. The preliminary

  1. Purposes and methods of scoring earthquake forecasts

    NASA Astrophysics Data System (ADS)

    Zhuang, J.

    2010-12-01

    There are two kinds of purposes in the studies on earthquake prediction or forecasts: one is to give a systematic estimation of earthquake risks in some particular region and period in order to give advice to governments and enterprises for the use of reducing disasters, the other one is to search for reliable precursors that can be used to improve earthquake prediction or forecasts. For the first case, a complete score is necessary, while for the latter case, a partial score, which can be used to evaluate whether the forecasts or predictions have some advantages than a well know model, is necessary. This study reviews different scoring methods for evaluating the performance of earthquake prediction and forecasts. Especially, the gambling scoring method, which is developed recently, shows its capacity in finding good points in an earthquake prediction algorithm or model that are not in a reference model, even if its overall performance is no better than the reference model.

  2. The October 1992 Parkfield, California, earthquake prediction

    USGS Publications Warehouse

    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.   

  3. Energy Partition and Variability of Earthquakes

    NASA Astrophysics Data System (ADS)

    Kanamori, H.

    2003-12-01

    During an earthquake the potential energy (strain energy + gravitational energy + rotational energy) is released, and the released potential energy (Δ W) is partitioned into radiated energy (ER), fracture energy (EG), and thermal energy (E H). How Δ W is partitioned into these energies controls the behavior of an earthquake. The merit of the slip-weakening concept is that only ER and EG control the dynamics, and EH can be treated separately to discuss the thermal characteristics of an earthquake. In general, if EG/E_R is small, the event is ``brittle", if EG /ER is large, the event is ``quasi static" or, in more common terms, ``slow earthquakes" or ``creep". If EH is very large, the event may well be called a thermal runaway rather than an earthquake. The difference in energy partition has important implications for the rupture initiation, evolution and excitation of long-period ground motions from very large earthquakes. We review the current state of knowledge on this problem in light of seismological observations and the basic physics of fracture. With seismological methods, we can measure only ER and the lower-bound of Δ W, Δ W0, and estimation of other energies involves many assumptions. ER: Although ER can be directly measured from the radiated waves, its determination is difficult because a large fraction of energy radiated at the source is attenuated during propagation. With the commonly used teleseismic and regional methods, only for events with MW>7 and MW>4, respectively, we can directly measure more than 10% of the total radiated energy. The rest must be estimated after correction for attenuation. Thus, large uncertainties are involved, especially for small earthquakes. Δ W0: To estimate Δ W0, estimation of the source dimension is required. Again, only for large earthquakes, the source dimension can be estimated reliably. With the source dimension, the static stress drop, Δ σ S, and Δ W0, can be estimated. EG: Seismologically, EG is the energy

  4. The California Earthquake Advisory Plan: A history

    USGS Publications Warehouse

    Roeloffs, Evelyn A.; Goltz, James D.

    2017-01-01

    Since 1985, the California Office of Emergency Services (Cal OES) has issued advisory statements to local jurisdictions and the public following seismic activity that scientists on the California Earthquake Prediction Evaluation Council view as indicating elevated probability of a larger earthquake in the same area during the next several days. These advisory statements are motivated by statistical studies showing that about 5% of moderate earthquakes in California are followed by larger events within a 10-km, five-day space-time window (Jones, 1985; Agnew and Jones, 1991; Reasenberg and Jones, 1994). Cal OES issued four earthquake advisories from 1985 to 1989. In October, 1990, the California Earthquake Advisory Plan formalized this practice, and six Cal OES Advisories have been issued since then. This article describes that protocol’s scientific basis and evolution.

  5. The U.S. Earthquake Prediction Program

    USGS Publications Warehouse

    Wesson, R.L.; Filson, J.R.

    1981-01-01

    There are two distinct motivations for earthquake prediction. The mechanistic approach aims to understand the processes leading to a large earthquake. The empirical approach is governed by the immediate need to protect lives and property. With our current lack of knowledge about the earthquake process, future progress cannot be made without gathering a large body of measurements. These are required not only for the empirical prediction of earthquakes, but also for the testing and development of hypotheses that further our understanding of the processes at work. The earthquake prediction program is basically a program of scientific inquiry, but one which is motivated by social, political, economic, and scientific reasons. It is a pursuit that cannot rely on empirical observations alone nor can it carried out solely on a blackboard or in a laboratory. Experiments must be carried out in the real Earth. 

  6. Parallelization of the Coupled Earthquake Model

    NASA Technical Reports Server (NTRS)

    Block, Gary; Li, P. Peggy; Song, Yuhe T.

    2007-01-01

    This Web-based tsunami simulation system allows users to remotely run a model on JPL s supercomputers for a given undersea earthquake. At the time of this reporting, predicting tsunamis on the Internet has never happened before. This new code directly couples the earthquake model and the ocean model on parallel computers and improves simulation speed. Seismometers can only detect information from earthquakes; they cannot detect whether or not a tsunami may occur as a result of the earthquake. When earthquake-tsunami models are coupled with the improved computational speed of modern, high-performance computers and constrained by remotely sensed data, they are able to provide early warnings for those coastal regions at risk. The software is capable of testing NASA s satellite observations of tsunamis. It has been successfully tested for several historical tsunamis, has passed all alpha and beta testing, and is well documented for users.

  7. Deep long-period earthquakes beneath Washington and Oregon volcanoes

    NASA Astrophysics Data System (ADS)

    Nichols, M. L.; Malone, S. D.; Moran, S. C.; Thelen, W. A.; Vidale, J. E.

    2011-03-01

    Deep long-period (DLP) earthquakes are an enigmatic type of seismicity occurring near or beneath volcanoes. They are commonly associated with the presence of magma, and found in some cases to correlate with eruptive activity. To more thoroughly understand and characterize DLP occurrence near volcanoes in Washington and Oregon, we systematically searched the Pacific Northwest Seismic Network (PNSN) triggered earthquake catalog for DLPs occurring between 1980 (when PNSN began collecting digital data) and October 2009. Through our analysis we identified 60 DLPs beneath six Cascade volcanic centers. No DLPs were associated with volcanic activity, including the 1980-1986 and 2004-2008 eruptions at Mount St. Helens. More than half of the events occurred near Mount Baker, where the background flux of magmatic gases is greatest among Washington and Oregon volcanoes. The six volcanoes with DLPs (counts in parentheses) are Mount Baker (31), Glacier Peak (9), Mount Rainier (9), Mount St. Helens (9), Three Sisters (1), and Crater Lake (1). No DLPs were identified beneath Mount Adams, Mount Hood, Mount Jefferson, or Newberry Volcano, although (except at Hood) that may be due in part to poorer network coverage. In cases where the DLPs do not occur directly beneath the volcanic edifice, the locations coincide with large structural faults that extend into the deep crust. Our observations suggest the occurrence of DLPs in these areas could represent fluid and/or magma transport along pre-existing tectonic structures in the middle crust.

  8. Deep long-period earthquakes beneath Washington and Oregon volcanoes

    USGS Publications Warehouse

    Nichols, M.L.; Malone, S.D.; Moran, S.C.; Thelen, W.A.; Vidale, J.E.

    2011-01-01

    Deep long-period (DLP) earthquakes are an enigmatic type of seismicity occurring near or beneath volcanoes. They are commonly associated with the presence of magma, and found in some cases to correlate with eruptive activity. To more thoroughly understand and characterize DLP occurrence near volcanoes in Washington and Oregon, we systematically searched the Pacific Northwest Seismic Network (PNSN) triggered earthquake catalog for DLPs occurring between 1980 (when PNSN began collecting digital data) and October 2009. Through our analysis we identified 60 DLPs beneath six Cascade volcanic centers. No DLPs were associated with volcanic activity, including the 1980-1986 and 2004-2008 eruptions at Mount St. Helens. More than half of the events occurred near Mount Baker, where the background flux of magmatic gases is greatest among Washington and Oregon volcanoes. The six volcanoes with DLPs (counts in parentheses) are Mount Baker (31), Glacier Peak (9), Mount Rainier (9), Mount St. Helens (9), Three Sisters (1), and Crater Lake (1). No DLPs were identified beneath Mount Adams, Mount Hood, Mount Jefferson, or Newberry Volcano, although (except at Hood) that may be due in part to poorer network coverage. In cases where the DLPs do not occur directly beneath the volcanic edifice, the locations coincide with large structural faults that extend into the deep crust. Our observations suggest the occurrence of DLPs in these areas could represent fluid and/or magma transport along pre-existing tectonic structures in the middle crust. ?? 2010 Elsevier B.V.

  9. What Can Sounds Tell Us About Earthquake Interactions?

    NASA Astrophysics Data System (ADS)

    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

  10. Earthquake activity along the Himalayan orogenic belt

    NASA Astrophysics Data System (ADS)

    Bai, L.; Mori, J. J.

    2017-12-01

    The collision between the Indian and Eurasian plates formed the Himalayas, the largest orogenic belt on the Earth. The entire region accommodates shallow earthquakes, while intermediate-depth earthquakes are concentrated at the eastern and western Himalayan syntaxis. Here we investigate the focal depths, fault plane solutions, and source rupture process for three earthquake sequences, which are located at the western, central and eastern regions of the Himalayan orogenic belt. The Pamir-Hindu Kush region is located at the western Himalayan syntaxis and is characterized by extreme shortening of the upper crust and strong interaction of various layers of the lithosphere. Many shallow earthquakes occur on the Main Pamir Thrust at focal depths shallower than 20 km, while intermediate-deep earthquakes are mostly located below 75 km. Large intermediate-depth earthquakes occur frequently at the western Himalayan syntaxis about every 10 years on average. The 2015 Nepal earthquake is located in the central Himalayas. It is a typical megathrust earthquake that occurred on the shallow portion of the Main Himalayan Thrust (MHT). Many of the aftershocks are located above the MHT and illuminate faulting structures in the hanging wall with dip angles that are steeper than the MHT. These observations provide new constraints on the collision and uplift processes for the Himalaya orogenic belt. The Indo-Burma region is located south of the eastern Himalayan syntaxis, where the strike of the plate boundary suddenly changes from nearly east-west at the Himalayas to nearly north-south at the Burma Arc. The Burma arc subduction zone is a typical oblique plate convergence zone. The eastern boundary is the north-south striking dextral Sagaing fault, which hosts many shallow earthquakes with focal depth less than 25 km. In contrast, intermediate-depth earthquakes along the subduction zone reflect east-west trending reverse faulting.

  11. Can We Teach Digital Natives Digital Literacy?

    ERIC Educational Resources Information Center

    Ng, Wan

    2012-01-01

    In recent years, there has been much debate about the concept of digital natives, in particular the differences between the digital natives' knowledge and adoption of digital technologies in informal versus formal educational contexts. This paper investigates the knowledge about educational technologies of a group of undergraduate students…

  12. Earthquake Records of North Anatolian Fault from Sapanca Lake Sediments, NW Anatolia

    NASA Astrophysics Data System (ADS)

    Yalamaz, Burak; Cagatay, Namık; Acar, Dursun; Demirbag, Emin; Gungor, Emin; Gungor, Nurdan; Gulen, Levent

    2014-05-01

    We determined earthquake records in sediment cores of Sapanca Lake which is a pull-apart basin located along the North Anatolian Fault zone in NW Anatolia. The lake has a maximum depth of 55 m, and a surface area of 46.8 km2, measuring 16 km in E-W and 5 km in N-S directions. A systematic study of the sedimentological, physical and geochemical properties of three water-sediment interface cores, up to 75.7 cm long, located along depth transects ranging from 43 to 51.5 m water depths. The cores were analyzed using Geotek Multi Sensor Core Logger (MSCL) for physical properties, laser particle size analyzer for granulometry, TOC Analyzer for Total Organic Content (TOC) and Total Inorganic Carbon (TIC) analysis, Itrax-XRF Core Scanner for elemental analysis and digital X-RAY Radiography. The geochronology was determined using AMS radiocarbon and radionuclide methods. The Sapanca Lake earthquake records are characterized by mass flow units consisting of grey or dark grey coarse to fine sand and silty mud with sharp basal and transional upper boundaries. The units commonly show normal size grading with their basal parts showing high density, and high magnetic susceptibility and enrichment in one or more elements, such as Si, Ca, Tİ, K, Rb, Zr and Fe, indicative of coarse detrial input. Based on radionuclide and radiocarbon analyses the mass flow units are correlated with 1999 İzmit and Düzce earthquakes (Mw=7.4 and 7.2, respectively) , 1967 Mudurnu earthquake (Mw= 6,8), and 1957 Abant (Mw= 7.1) earthquake. Keywords: Sapanca Lake, North Anatolian Fault, Earthquake, Grain size, Itrax-XRF, MSCL

  13. Source parameters and tectonic interpretation of recent earthquakes (1995 1997) in the Pannonian basin

    NASA Astrophysics Data System (ADS)

    Badawy, Ahmed; Horváth, Frank; Tóth, László

    2001-01-01

    From January 1995 to December 1997, about 74 earthquakes were located in the Pannonian basin and digitally recorded by a recently established network of seismological stations in Hungary. On reviewing the notable events, about 12 earthquakes were reported as felt with maximum intensity varying between 4 and 6 MSK. The dynamic source parameters of these earthquakes have been derived from P-wave displacement spectra. The displacement source spectra obtained are characterised by relatively small values of corner frequency ( f0) ranging between 2.5 and 10 Hz. The seismic moments change from 1.48×10 20 to 1.3×10 23 dyne cm, stress drops from 0.25 to 76.75 bar, fault length from 0.42 to 1.7 km and relative displacement from 0.05 to 15.35 cm. The estimated source parameters suggest a good agreement with the scaling law for small earthquakes. The small values of stress drops in the studied earthquakes can be attributed to the low strength of crustal materials in the Pannonian basin. However, the values of stress drops are not different for earthquake with thrust or normal faulting focal mechanism solutions. It can be speculated that an increase of the seismic activity in the Pannonian basin can be predicted in the long run because extensional development ceased and structural inversion is in progress. Seismic hazard assessment is a delicate job due to the inadequate knowledge of the seismo-active faults, particularly in the interior part of the Pannonian basin.

  14. Revised history of the great Kanto earthquakes from the ages of Holocene marine terraces

    NASA Astrophysics Data System (ADS)

    Komori, J.; Shishikura, M.; Ando, R.; Yokoyama, Y.; Miyairi, Y.

    2017-12-01

    The Sagami Trough, where the Philippine Sea Plate subducts beneath the continental plate of the Japanese Archipelago, is considered to be a typical example where characteristic earthquakes repeat. Previous studies in some decades claimed that approximate M8 interplate earthquakes, called Genroku type earthquakes, occur with the interval of 2,000―2,700 years. In this study, we measured the emergence ages of the marine terraces in the Chikura lowland, which lies to the southeast of the Boso Peninsula, to reevaluate the history of the great earthquake over the past 10,000 years. The dates of the marine terraces are measured via radiocarbon dating of shell fossils obtained from the marine deposits. The sampling method employed in this study collects core samples using a dense and systematic drilling survey, which increased the reliability when correlating shell fossils with marine terraces. Moreover, we explored the surface profiles of the terraces with detailed digital elevation model (DEM) data obtained using LiDAR. The maximum emergence ages of the marine terraces were dated at 6300 cal yBP, 3000 cal yBP, and 2200 cal yBP from the top terrace excepting the lowest terrace (which was estimated at AD1703). In addition, another previously unrecognized terrace was detected between the highest and the second terrace in both the dating and the geomorphological analyses and was dated at 5800 cal yBP. The newly obtained ages are nearly a thousand of years younger than previously estimated ages; consequently, the intervals of the great earthquakes that occurred along the Sagami Trough are estimated to be much shorter and more varied than those of previous estimations. This result indicates that the temporal pattern of the large earthquakes occur along the Sagami Trough does not follow a characteristic pattern as previously considered.

  15. Normal fault earthquakes or graviquakes

    PubMed Central

    Doglioni, C.; Carminati, E.; Petricca, P.; Riguzzi, F.

    2015-01-01

    Earthquakes are dissipation of energy throughout elastic waves. Canonically is the elastic energy accumulated during the interseismic period. However, in crustal extensional settings, gravity is the main energy source for hangingwall fault collapsing. Gravitational potential is about 100 times larger than the observed magnitude, far more than enough to explain the earthquake. Therefore, normal faults have a different mechanism of energy accumulation and dissipation (graviquakes) with respect to other tectonic settings (strike-slip and contractional), where elastic energy allows motion even against gravity. The bigger the involved volume, the larger is their magnitude. The steeper the normal fault, the larger is the vertical displacement and the larger is the seismic energy released. Normal faults activate preferentially at about 60° but they can be shallower in low friction rocks. In low static friction rocks, the fault may partly creep dissipating gravitational energy without releasing great amount of seismic energy. The maximum volume involved by graviquakes is smaller than the other tectonic settings, being the activated fault at most about three times the hypocentre depth, explaining their higher b-value and the lower magnitude of the largest recorded events. Having different phenomenology, graviquakes show peculiar precursors. PMID:26169163

  16. Comparing methods for Earthquake Location

    NASA Astrophysics Data System (ADS)

    Turkaya, Semih; Bodin, Thomas; Sylvander, Matthieu; Parroucau, Pierre; Manchuel, Kevin

    2017-04-01

    There are plenty of methods available for locating small magnitude point source earthquakes. However, it is known that these different approaches produce different results. For each approach, results also depend on a number of parameters which can be separated into two main branches: (1) parameters related to observations (number and distribution of for example) and (2) parameters related to the inversion process (velocity model, weighting parameters, initial location etc.). Currently, the results obtained from most of the location methods do not systematically include quantitative uncertainties. The effect of the selected parameters on location uncertainties is also poorly known. Understanding the importance of these different parameters and their effect on uncertainties is clearly required to better constrained knowledge on fault geometry, seismotectonic processes and at the end to improve seismic hazard assessment. In this work, realized in the frame of the SINAPS@ research program (http://www.institut-seism.fr/projets/sinaps/), we analyse the effect of different parameters on earthquakes location (e.g. type of phase, max. hypocentral separation etc.). We compare several codes available (Hypo71, HypoDD, NonLinLoc etc.) and determine their strengths and weaknesses in different cases by means of synthetic tests. The work, performed for the moment on synthetic data, is planned to be applied, in a second step, on data collected by the Midi-Pyrénées Observatory (OMP).

  17. Earthquake-Ionosphere Coupling Processes

    NASA Astrophysics Data System (ADS)

    Kamogawa, Masashi

    After a giant earthquake (EQ), acoustic and gravity waves are excited by the displacement of land and sea surface, propagate through atmosphere, and then reach thermosphere, which causes ionospheric disturbances. This phenomenon was detected first by ionosonde and by HF Doppler sounderin the 1964 M9.2 Great Alaskan EQ. Developing Global Positioning System (GPS), seismogenic ionospheric disturbance detected by total electron content (TEC) measurement has been reported. A value of TEC is estimated by the phase difference between two different carrier frequencies through the propagation in the dispersive ionospheric plasma. The variation of TEC is mostly similar to that of F-region plasma. Acoustic-gravity waves triggered by an earthquake [Heki and Ping, EPSL, 2005; Liu et al., JGR, 2010] and a tsunami [Artu et al., GJI, 2005; Liu et al., JGR, 2006; Rolland, GRL, 2010] disturb the ionosphere and travel in the ionosphere. Besides the traveling ionospheric disturbances, ionospheric disturbances excited by Rayleigh waves [Ducic et al, GRL, 2003; Liu et al., GRL, 2006] as well as post-seismic 4-minute monoperiodic atmospheric resonances [Choosakul et al., JGR, 2009] have been observed after the large earthquakes. Since GPS Earth Observation Network System (GEONET) with more than 1200 GPS receiving points in Japan is a dense GPS network, seismogenic ionospheric disturbance is spatially observed. In particular, the seismogenic ionospheric disturbance caused by the M9.0 off the Pacific coast of Tohoku EQ (henceforth the Tohoku EQ) on 11 March 2011 was clearly observed. Approximately 9 minutes after the mainshock, acoustic waves which propagated radially emitted from the tsunami source area were observed through the TEC measurement (e. g., Liu et al. [JGR, 2011]). Moreover, there was a depression of TEC lasting for several tens of minutes after a huge earthquake, which was a large-scale phenomenon extending to a radius of a few hundred kilometers. This TEC depression may be

  18. Understanding earthquake from the granular physics point of view — Causes of earthquake, earthquake precursors and predictions

    NASA Astrophysics Data System (ADS)

    Lu, Kunquan; Hou, Meiying; Jiang, Zehui; Wang, Qiang; Sun, Gang; Liu, Jixing

    2018-03-01

    We treat the earth crust and mantle as large scale discrete matters based on the principles of granular physics and existing experimental observations. Main outcomes are: A granular model of the structure and movement of the earth crust and mantle is established. The formation mechanism of the tectonic forces, which causes the earthquake, and a model of propagation for precursory information are proposed. Properties of the seismic precursory information and its relevance with the earthquake occurrence are illustrated, and principle of ways to detect the effective seismic precursor is elaborated. The mechanism of deep-focus earthquake is also explained by the jamming-unjamming transition of the granular flow. Some earthquake phenomena which were previously difficult to understand are explained, and the predictability of the earthquake is discussed. Due to the discrete nature of the earth crust and mantle, the continuum theory no longer applies during the quasi-static seismological process. In this paper, based on the principles of granular physics, we study the causes of earthquakes, earthquake precursors and predictions, and a new understanding, different from the traditional seismological viewpoint, is obtained.

  19. Are Earthquakes Predictable? A Study on Magnitude Correlations in Earthquake Catalog and Experimental Data

    NASA Astrophysics Data System (ADS)

    Stavrianaki, K.; Ross, G.; Sammonds, P. R.

    2015-12-01

    The clustering of earthquakes in time and space is widely accepted, however the existence of correlations in earthquake magnitudes is more questionable. In standard models of seismic activity, it is usually assumed that magnitudes are independent and therefore in principle unpredictable. Our work seeks to test this assumption by analysing magnitude correlation between earthquakes and their aftershocks. To separate mainshocks from aftershocks, we perform stochastic declustering based on the widely used Epidemic Type Aftershock Sequence (ETAS) model, which allows us to then compare the average magnitudes of aftershock sequences to that of their mainshock. The results of earthquake magnitude correlations were compared with acoustic emissions (AE) from laboratory analog experiments, as fracturing generates both AE at the laboratory scale and earthquakes on a crustal scale. Constant stress and constant strain rate experiments were done on Darley Dale sandstone under confining pressure to simulate depth of burial. Microcracking activity inside the rock volume was analyzed by the AE technique as a proxy for earthquakes. Applying the ETAS model to experimental data allowed us to validate our results and provide for the first time a holistic view on the correlation of earthquake magnitudes. Additionally we search the relationship between the conditional intensity estimates of the ETAS model and the earthquake magnitudes. A positive relation would suggest the existence of magnitude correlations. The aim of this study is to observe any trends of dependency between the magnitudes of aftershock earthquakes and the earthquakes that trigger them.

  20. Understanding earthquake hazards in urban areas - Evansville Area Earthquake Hazards Mapping Project

    USGS Publications Warehouse

    Boyd, Oliver S.

    2012-01-01

    The region surrounding Evansville, Indiana, has experienced minor damage from earthquakes several times in the past 200 years. Because of this history and the proximity of Evansville to the Wabash Valley and New Madrid seismic zones, there is concern among nearby communities about hazards from earthquakes. Earthquakes currently cannot be predicted, but scientists can estimate how strongly the ground is likely to shake as a result of an earthquake and are able to design structures to withstand this estimated ground shaking. Earthquake-hazard maps provide one way of conveying such information and can help the region of Evansville prepare for future earthquakes and reduce earthquake-caused loss of life and financial and structural loss. The Evansville Area Earthquake Hazards Mapping Project (EAEHMP) has produced three types of hazard maps for the Evansville area: (1) probabilistic seismic-hazard maps show the ground motion that is expected to be exceeded with a given probability within a given period of time; (2) scenario ground-shaking maps show the expected shaking from two specific scenario earthquakes; (3) liquefaction-potential maps show how likely the strong ground shaking from the scenario earthquakes is to produce liquefaction. These maps complement the U.S. Geological Survey's National Seismic Hazard Maps but are more detailed regionally and take into account surficial geology, soil thickness, and soil stiffness; these elements greatly affect ground shaking.

  1. Anomalies of rupture velocity in deep earthquakes

    NASA Astrophysics Data System (ADS)

    Suzuki, M.; Yagi, Y.

    2010-12-01

    Explaining deep seismicity is a long-standing challenge in earth science. Deeper than 300 km, the occurrence rate of earthquakes with depth remains at a low level until ~530 km depth, then rises until ~600 km, finally terminate near 700 km. Given the difficulty of estimating fracture properties and observing the stress field in the mantle transition zone (410-660 km), the seismic source processes of deep earthquakes are the most important information for understanding the distribution of deep seismicity. However, in a compilation of seismic source models of deep earthquakes, the source parameters for individual deep earthquakes are quite varied [Frohlich, 2006]. Rupture velocities for deep earthquakes estimated using seismic waveforms range from 0.3 to 0.9Vs, where Vs is the shear wave velocity, a considerably wider range than the velocities for shallow earthquakes. The uncertainty of seismic source models prevents us from determining the main characteristics of the rupture process and understanding the physical mechanisms of deep earthquakes. Recently, the back projection method has been used to derive a detailed and stable seismic source image from dense seismic network observations [e.g., Ishii et al., 2005; Walker et al., 2005]. Using this method, we can obtain an image of the seismic source process from the observed data without a priori constraints or discarding parameters. We applied the back projection method to teleseismic P-waveforms of 24 large, deep earthquakes (moment magnitude Mw ≥ 7.0, depth ≥ 300 km) recorded since 1994 by the Data Management Center of the Incorporated Research Institutions for Seismology (IRIS-DMC) and reported in the U.S. Geological Survey (USGS) catalog, and constructed seismic source models of deep earthquakes. By imaging the seismic rupture process for a set of recent deep earthquakes, we found that the rupture velocities are less than about 0.6Vs except in the depth range of 530 to 600 km. This is consistent with the depth

  2. Southern California Earthquake Center/Undergraduate Studies in Earthquake Information Technology (SCEC/UseIT): Towards the Next Generation of Internship

    NASA Astrophysics Data System (ADS)

    Perry, S.; Benthien, M.; Jordan, T. H.

    2005-12-01

    The SCEC/UseIT internship program is training the next generation of earthquake scientist, with methods that can be adapted to other disciplines. UseIT interns work collaboratively, in multi-disciplinary teams, conducting computer science research that is needed by earthquake scientists. Since 2002, the UseIT program has welcomed 64 students, in some two dozen majors, at all class levels, from schools around the nation. Each summer''s work is posed as a ``Grand Challenge.'' The students then organize themselves into project teams, decide how to proceed, and pool their diverse talents and backgrounds. They have traditional mentors, who provide advice and encouragement, but they also mentor one another, and this has proved to be a powerful relationship. Most begin with fear that their Grand Challenge is impossible, and end with excitement and pride about what they have accomplished. The 22 UseIT interns in summer, 2005, were primarily computer science and engineering majors, with others in geology, mathematics, English, digital media design, physics, history, and cinema. The 2005 Grand Challenge was to "build an earthquake monitoring system" to aid scientists who must visualize rapidly evolving earthquake sequences and convey information to emergency personnel and the public. Most UseIT interns were engaged in software engineering, bringing new datasets and functionality to SCEC-VDO (Virtual Display of Objects), a 3D visualization software that was prototyped by interns last year, using Java3D and an extensible, plug-in architecture based on the Eclipse Integrated Development Environment. Other UseIT interns used SCEC-VDO to make animated movies, and experimented with imagery in order to communicate concepts and events in earthquake science. One movie-making project included the creation of an assessment to test the effectiveness of the movie''s educational message. Finally, one intern created an interactive, multimedia presentation of the UseIT program.

  3. Digital photorefraction

    NASA Astrophysics Data System (ADS)

    Costa, Manuel F. M.; Jorge, Jorge M.

    1998-01-01

    The early evaluation of the visual status of human infants is of a critical importance. It is of utmost importance to the development of the child's visual system that she perceives clear, focused, retinal images. Furthermore if the refractive problems are not corrected in due time amblyopia may occur. Photorefraction is a non-invasive clinical tool rather convenient for application to this kind of population. A qualitative or semi-quantitative information about refractive errors, accommodation, strabismus, amblyogenic factors and some pathologies (cataracts) can the easily obtained. The photorefraction experimental setup we established using new technological breakthroughs on the fields of imaging devices, image processing and fiber optics, allows the implementation of both the isotropic and eccentric photorefraction approaches. Essentially both methods consist on delivering a light beam into the eyes. It is refracted by the ocular media, strikes the retina, focusing or not, reflects off and is collected by a camera. The system is formed by one CCD color camera and a light source. A beam splitter in front of the camera's objective allows coaxial illumination and observation. An optomechanical system also allows eccentric illumination. The light source is a flash type one and is synchronized with the camera's image acquisition. The camera's image is digitized displayed in real time. Image processing routines are applied for image's enhancement and feature extraction.

  4. Digital photorefraction

    NASA Astrophysics Data System (ADS)

    Costa, Manuel F.; Jorge, Jorge M.

    1997-12-01

    The early evaluation of the visual status of human infants is of a critical importance. It is of utmost importance to the development of the child's visual system that she perceives clear, focused, retinal images. Furthermore if the refractive problems are not corrected in due time amblyopia may occur. Photorefraction is a non-invasive clinical tool rather convenient for application to this kind of population. A qualitative or semi-quantitative information about refractive errors, accommodation, strabismus, amblyogenic factors and some pathologies (cataracts) can the easily obtained. The photorefraction experimental setup we established using new technological breakthroughs on the fields of imaging devices, image processing and fiber optics, allows the implementation of both the isotropic and eccentric photorefraction approaches. Essentially both methods consist on delivering a light beam into the eyes. It is refracted by the ocular media, strikes the retina, focusing or not, reflects off and is collected by a camera. The system is formed by one CCD color camera and a light source. A beam splitter in front of the camera's objective allows coaxial illumination and observation. An optomechanical system also allows eccentric illumination. The light source is a flash type one and is synchronized with the camera's image acquisition. The camera's image is digitized displayed in real time. Image processing routines are applied for image's enhancement and feature extraction.

  5. 78 FR 64973 - Scientific Earthquake Studies Advisory Committee (SESAC)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-30

    ... DEPARTMENT OF THE INTERIOR Geological Survey [GX14GG009950000] Scientific Earthquake Studies... Public Law 106-503, the Scientific Earthquake Studies Advisory Committee (SESAC) will hold its next... warning and national earthquake hazard mapping. Meetings of the Scientific Earthquake Studies Advisory...

  6. Earthquakes

    MedlinePlus

    ... Situations Food and Water People with Special Needs PSAs and Podcasts Extreme Heat About Extreme Heat Protecting ... to Stay Cool Missouri Cooling Centers Extreme Heat PSAs Related Links MMWR Bibliography Floods Flood Readiness Personal ...

  7. Frog Swarms: Earthquake Precursors or False Alarms?

    PubMed Central

    Grant, Rachel A.; Conlan, Hilary

    2013-01-01

    Simple Summary Media reports linking unusual animal behaviour with earthquakes can potentially create false alarms and unnecessary anxiety among people that live in earthquake risk zones. Recently large frog swarms in China and elsewhere have been reported as earthquake precursors in the media. By examining international media reports of frog swarms since 1850 in comparison to earthquake data, it was concluded that frog swarms are naturally occurring dispersal behaviour of juveniles and are not associated with earthquakes. However, the media in seismic risk areas may be more likely to report frog swarms, and more likely to disseminate reports on frog swarms after earthquakes have occurred, leading to an apparent link between frog swarms and earthquakes. Abstract In short-term earthquake risk forecasting, the avoidance of false alarms is of utmost importance to preclude the possibility of unnecessary panic among populations in seismic hazard areas. Unusual animal behaviour prior to earthquakes has been reported for millennia but has rarely been scientifically documented. Recently large migrations or unusual behaviour of amphibians have been linked to large earthquakes, and media reports of large frog and toad migrations in areas of high seismic risk such as Greece and China have led to fears of a subsequent large earthquake. However, at certain times of year large migrations are part of the normal behavioural repertoire of amphibians. News reports of “frog swarms” from 1850 to the present day were examined for evidence that this behaviour is a precursor to large earthquakes. It was found that only two of 28 reported frog swarms preceded large earthquakes (Sichuan province, China in 2008 and 2010). All of the reported mass migrations of amphibians occurred in late spring, summer and autumn and appeared to relate to small juvenile anurans (frogs and toads). It was concluded that most reported “frog swarms” are actually normal behaviour, probably caused by

  8. The repetition of large-earthquake ruptures.

    PubMed Central

    Sieh, K

    1996-01-01

    This survey of well-documented repeated fault rupture confirms that some faults have exhibited a "characteristic" behavior during repeated large earthquakes--that is, the magnitude, distribution, and style of slip on the fault has repeated during two or more consecutive events. In two cases faults exhibit slip functions that vary little from earthquake to earthquake. In one other well-documented case, however, fault lengths contrast markedly for two consecutive ruptures, but the amount of offset at individual sites was similar. Adjacent individual patches, 10 km or more in length, failed singly during one event and in tandem during the other. More complex cases of repetition may also represent the failure of several distinct patches. The faults of the 1992 Landers earthquake provide an instructive example of such complexity. Together, these examples suggest that large earthquakes commonly result from the failure of one or more patches, each characterized by a slip function that is roughly invariant through consecutive earthquake cycles. The persistence of these slip-patches through two or more large earthquakes indicates that some quasi-invariant physical property controls the pattern and magnitude of slip. These data seem incompatible with theoretical models that produce slip distributions that are highly variable in consecutive large events. Images Fig. 3 Fig. 7 Fig. 9 PMID:11607662

  9. The Road to Total Earthquake Safety

    NASA Astrophysics Data System (ADS)

    Frohlich, Cliff

    Cinna Lomnitz is possibly the most distinguished earthquake seismologist in all of Central and South America. Among many other credentials, Lomnitz has personally experienced the shaking and devastation that accompanied no fewer than five major earthquakes—Chile, 1939; Kern County, California, 1952; Chile, 1960; Caracas,Venezuela, 1967; and Mexico City, 1985. Thus he clearly has much to teach someone like myself, who has never even actually felt a real earthquake.What is this slim book? The Road to Total Earthquake Safety summarizes Lomnitz's May 1999 presentation at the Seventh Mallet-Milne Lecture, sponsored by the Society for Earthquake and Civil Engineering Dynamics. His arguments are motivated by the damage that occurred in three earthquakes—Mexico City, 1985; Loma Prieta, California, 1989; and Kobe, Japan, 1995. All three quakes occurred in regions where earthquakes are common. Yet in all three some of the worst damage occurred in structures located a significant distance from the epicenter and engineered specifically to resist earthquakes. Some of the damage also indicated that the structures failed because they had experienced considerable rotational or twisting motion. Clearly, Lomnitz argues, there must be fundamental flaws in the usually accepted models explaining how earthquakes generate strong motions, and how we should design resistant structures.

  10. Analysis of the Seismicity Preceding Large Earthquakes

    NASA Astrophysics Data System (ADS)

    Stallone, A.; Marzocchi, W.

    2016-12-01

    The most common earthquake forecasting models assume that the magnitude of the next earthquake is independent from the past. This feature is probably one of the most severe limitations of the capability to forecast large earthquakes.In this work, we investigate empirically on this specific aspect, exploring whether spatial-temporal variations in seismicity encode some information on the magnitude of the future earthquakes. For this purpose, and to verify the universality of the findings, we consider seismic catalogs covering quite different space-time-magnitude windows, such as the Alto Tiberina Near Fault Observatory (TABOO) catalogue, and the California and Japanese seismic catalog. Our method is inspired by the statistical methodology proposed by Zaliapin (2013) to distinguish triggered and background earthquakes, using the nearest-neighbor clustering analysis in a two-dimension plan defined by rescaled time and space. In particular, we generalize the metric based on the nearest-neighbor to a metric based on the k-nearest-neighbors clustering analysis that allows us to consider the overall space-time-magnitude distribution of k-earthquakes (k-foreshocks) which anticipate one target event (the mainshock); then we analyze the statistical properties of the clusters identified in this rescaled space. In essence, the main goal of this study is to verify if different classes of mainshock magnitudes are characterized by distinctive k-foreshocks distribution. The final step is to show how the findings of this work may (or not) improve the skill of existing earthquake forecasting models.

  11. Scaling of seismic memory with earthquake size

    NASA Astrophysics Data System (ADS)

    Zheng, Zeyu; Yamasaki, Kazuko; Tenenbaum, Joel; Podobnik, Boris; Tamura, Yoshiyasu; Stanley, H. Eugene

    2012-07-01

    It has been observed that discrete earthquake events possess memory, i.e., that events occurring in a particular location are dependent on the history of that location. We conduct an analysis to see whether continuous real-time data also display a similar memory and, if so, whether such autocorrelations depend on the size of earthquakes within close spatiotemporal proximity. We analyze the seismic wave form database recorded by 64 stations in Japan, including the 2011 “Great East Japan Earthquake,” one of the five most powerful earthquakes ever recorded, which resulted in a tsunami and devastating nuclear accidents. We explore the question of seismic memory through use of mean conditional intervals and detrended fluctuation analysis (DFA). We find that the wave form sign series show power-law anticorrelations while the interval series show power-law correlations. We find size dependence in earthquake autocorrelations: as the earthquake size increases, both of these correlation behaviors strengthen. We also find that the DFA scaling exponent α has no dependence on the earthquake hypocenter depth or epicentral distance.

  12. Next-Day Earthquake Forecasts for California

    NASA Astrophysics Data System (ADS)

    Werner, M. J.; Jackson, D. D.; Kagan, Y. Y.

    2008-12-01

    We implemented a daily forecast of m > 4 earthquakes for California in the format suitable for testing in community-based earthquake predictability experiments: Regional Earthquake Likelihood Models (RELM) and the Collaboratory for the Study of Earthquake Predictability (CSEP). The forecast is based on near-real time earthquake reports from the ANSS catalog above magnitude 2 and will be available online. The model used to generate the forecasts is based on the Epidemic-Type Earthquake Sequence (ETES) model, a stochastic model of clustered and triggered seismicity. Our particular implementation is based on the earlier work of Helmstetter et al. (2006, 2007), but we extended the forecast to all of Cali-fornia, use more data to calibrate the model and its parameters, and made some modifications. Our forecasts will compete against the Short-Term Earthquake Probabilities (STEP) forecasts of Gersten-berger et al. (2005) and other models in the next-day testing class of the CSEP experiment in California. We illustrate our forecasts with examples and discuss preliminary results.

  13. Earthquake Occurrence in Bangladesh and Surrounding Region

    NASA Astrophysics Data System (ADS)

    Al-Hussaini, T. M.; Al-Noman, M.

    2011-12-01

    The collision of the northward moving Indian plate with the Eurasian plate is the cause of frequent earthquakes in the region comprising Bangladesh and neighbouring India, Nepal and Myanmar. Historical records indicate that Bangladesh has been affected by five major earthquakes of magnitude greater than 7.0 (Richter scale) during 1869 to 1930. This paper presents some statistical observations of earthquake occurrence in fulfilment of a basic groundwork for seismic hazard assessment of this region. An up to date catalogue covering earthquake information in the region bounded within 17°-30°N and 84°-97°E for the period of historical period to 2010 is derived from various reputed international sources including ISC, IRIS, Indian sources and available publications. Careful scrutiny is done to remove duplicate or uncertain earthquake events. Earthquake magnitudes in the range of 1.8 to 8.1 have been obtained and relationships between different magnitude scales have been studied. Aftershocks are removed from the catalogue using magnitude dependent space window and time window. The main shock data are then analyzed to obtain completeness period for different magnitudes evaluating their temporal homogeneity. Spatial and temporal distribution of earthquakes, magnitude-depth histograms and other statistical analysis are performed to understand the distribution of seismic activity in this region.

  14. The Uniform California Earthquake Rupture Forecast, Version 2 (UCERF 2)

    USGS Publications Warehouse

    ,

    2008-01-01

    California?s 35 million people live among some of the most active earthquake faults in the United States. Public safety demands credible assessments of the earthquake hazard to maintain appropriate building codes for safe construction and earthquake insurance for loss protection. Seismic hazard analysis begins with an earthquake rupture forecast?a model of probabilities that earthquakes of specified magnitudes, locations, and faulting types will occur during a specified time interval. This report describes a new earthquake rupture forecast for California developed by the 2007 Working Group on California Earthquake Probabilities (WGCEP 2007).

  15. Modified Mercalli Intensity for scenario earthquakes in Evansville, Indiana

    USGS Publications Warehouse

    Cramer, Chris; Haase, Jennifer; Boyd, Oliver

    2012-01-01

    Evansville, Indiana, has experienced minor damage from earthquakes several times in the past 200 years. Because of this history and the fact that Evansville is close to the Wabash Valley and New Madrid seismic zones, there is concern about the hazards from earthquakes. Earthquakes currently cannot be predicted, but scientists can estimate how strongly the ground is likely to shake as a result of an earthquake. Earthquake-hazard maps provide one way of conveying such estimates of strong ground shaking and will help the region prepare for future earthquakes and reduce earthquake-caused losses.

  16. A new prototype system for earthquake early warning in Taiwan

    NASA Astrophysics Data System (ADS)

    Hsiao, N.; Wu, Y.; Chen, D.; Kuo, K.; Shin, T.

    2009-12-01

    Earthquake early warning (EEW) system has already been developed and tested in Taiwan for more than ten years. With the implementation of a real-time strong-motion network by the Central Weather Bureau (CWB), a virtual sub-network (VSN) system based on regional early warning approach was utilized at the first attempt. In order to shorten the processing time, seismic waveforms in a 10-sec time window starting from the first P-wave arrival time at the nearest station are used to determine the hypocenter and earthquake magnitude which is dubbed ML10. Since 2001, this EEW system has responded to a total of 255 events with magnitude greater than 4.5 occurred inland or off the coast of Taiwan. The system is capable of issuing an earthquake report within 20 sec of its occurrence with good magnitude estimations for events up to magnitude 6.5. This will provide early warning for metropolitan areas located 70 km away from the epicentre. In the latest development, a new prototype EEW system based on P-wave method was developed. Instead of ML10, we adopt the “Pd magnitude”, MPd, as our magnitude indicator in the new system. Pd is defined as the peak amplitude of the initial P-wave displacement. In the previous studies, by analyzing the Pd attenuation relationship with earthquake magnitudes, Pd was proved to be a good magnitude estimator for EEW purpose. Therefore, we adopt the Pd magnitude in developing our next generation EEW system. The new system is designed and constructed based on the Central Weather Bureau Seismographic Network (CWBSN). The CWBSN is a real-time seismographic network with more than one hundred digital telemetered seismic stations distributed over the entire Taiwan. Currently, there are three types of seismic instruments installed at the stations, either co-site or separately installed, including short-period seismographs, accelerometers, and broadband instruments. For the need of integral data processing, we use the Earthworm system as a common

  17. POST Earthquake Debris Management — AN Overview

    NASA Astrophysics Data System (ADS)

    Sarkar, Raju

    Every year natural disasters, such as fires, floods, earthquakes, hurricanes, landslides, tsunami, and tornadoes, challenge various communities of the world. Earthquakes strike with varying degrees of severity and pose both short- and long-term challenges to public service providers. Earthquakes generate shock waves and displace the ground along fault lines. These seismic forces can bring down buildings and bridges in a localized area and damage buildings and other structures in a far wider area. Secondary damage from fires, explosions, and localized flooding from broken water pipes can increase the amount of debris. Earthquake debris includes building materials, personal property, and sediment from landslides. The management of this debris, as well as the waste generated during the reconstruction works, can place significant challenges on the national and local capacities. Debris removal is a major component of every post earthquake recovery operation. Much of the debris generated from earthquake is not hazardous. Soil, building material, and green waste, such as trees and shrubs, make up most of the volume of earthquake debris. These wastes not only create significant health problems and a very unpleasant living environment if not disposed of safely and appropriately, but also can subsequently impose economical burdens on the reconstruction phase. In practice, most of the debris may be either disposed of at landfill sites, reused as materials for construction or recycled into useful commodities Therefore, the debris clearance operation should focus on the geotechnical engineering approach as an important post earthquake issue to control the quality of the incoming flow of potential soil materials. In this paper, the importance of an emergency management perspective in this geotechnical approach that takes into account the different criteria related to the operation execution is proposed by highlighting the key issues concerning the handling of the construction

  18. POST Earthquake Debris Management - AN Overview

    NASA Astrophysics Data System (ADS)

    Sarkar, Raju

    Every year natural disasters, such as fires, floods, earthquakes, hurricanes, landslides, tsunami, and tornadoes, challenge various communities of the world. Earthquakes strike with varying degrees of severity and pose both short- and long-term challenges to public service providers. Earthquakes generate shock waves and displace the ground along fault lines. These seismic forces can bring down buildings and bridges in a localized area and damage buildings and other structures in a far wider area. Secondary damage from fires, explosions, and localized flooding from broken water pipes can increase the amount of debris. Earthquake debris includes building materials, personal property, and sediment from landslides. The management of this debris, as well as the waste generated during the reconstruction works, can place significant challenges on the national and local capacities. Debris removal is a major component of every post earthquake recovery operation. Much of the debris generated from earthquake is not hazardous. Soil, building material, and green waste, such as trees and shrubs, make up most of the volume of earthquake debris. These wastes not only create significant health problems and a very unpleasant living environment if not disposed of safely and appropriately, but also can subsequently impose economical burdens on the reconstruction phase. In practice, most of the debris may be either disposed of at landfill sites, reused as materials for construction or recycled into useful commodities Therefore, the debris clearance operation should focus on the geotechnical engineering approach as an important post earthquake issue to control the quality of the incoming flow of potential soil materials. In this paper, the importance of an emergency management perspective in this geotechnical approach that takes into account the different criteria related to the operation execution is proposed by highlighting the key issues concerning the handling of the construction

  19. Automatic Earthquake Detection by Active Learning

    NASA Astrophysics Data System (ADS)

    Bergen, K.; Beroza, G. C.

    2017-12-01

    In recent years, advances in machine learning have transformed fields such as image recognition, natural language processing and recommender systems. Many of these performance gains have relied on the availability of large, labeled data sets to train high-accuracy models; labeled data sets are those for which each sample includes a target class label, such as waveforms tagged as either earthquakes or noise. Earthquake seismologists are increasingly leveraging machine learning and data mining techniques to detect and analyze weak earthquake signals in large seismic data sets. One of the challenges in applying machine learning to seismic data sets is the limited labeled data problem; learning algorithms need to be given examples of earthquake waveforms, but the number of known events, taken from earthquake catalogs, may be insufficient to build an accurate detector. Furthermore, earthquake catalogs are known to be incomplete, resulting in training data that may be biased towards larger events and contain inaccurate labels. This challenge is compounded by the class imbalance problem; the events of interest, earthquakes, are infrequent relative to noise in continuous data sets, and many learning algorithms perform poorly on rare classes. In this work, we investigate the use of active learning for automatic earthquake detection. Active learning is a type of semi-supervised machine learning that uses a human-in-the-loop approach to strategically supplement a small initial training set. The learning algorithm incorporates domain expertise through interaction between a human expert and the algorithm, with the algorithm actively posing queries to the user to improve detection performance. We demonstrate the potential of active machine learning to improve earthquake detection performance with limited available training data.

  20. Earthquake Protection Measures for People with Disabilities

    NASA Astrophysics Data System (ADS)

    Gountromichou, C.; Kourou, A.; Kerpelis, P.

    2009-04-01

    The problem of seismic safety for people with disabilities not only exists but is also urgent and of primary importance. Working towards disability equality, Earthquake Planning and Protection Organization of Greece (E.P.P.O.) has developed an educational scheme for people with disabilities in order to guide them to develop skills to protect themselves as well as to take the appropriate safety measures before, during and after an earthquake. The framework of this initiative includes a number of actions have been already undertaken, including the following: a. Recently, the main guidelines have been published to help people who have physical, cognitive, visual, or auditory disabilities to cope with a destructive earthquake. Of great importance, in case of people with disabilities, is to be prepared for the disaster, with several measures that must be taken starting today. In the pre-earthquake period, it is important that these people, in addition to other measures, do the following: - Create a Personal Support Network The Personal Support Network should be a group of at least three trustful people that can assist the disabled person to prepare for a disastrous event and to recover after it. - Complete a Personal Assessment The environment may change after a destructive earthquake. People with disabilities are encouraged to make a list of their personal needs and their resources for meeting them in a disaster environment. b. Lectures and training seminars on earthquake protection are given for students, teachers and educators in Special Schools for disabled people, mainly for informing and familiarizing them with earthquakes and with safety measures. c. Many earthquake drills have already taken place, for each disability, in order to share good practices and lessons learned to further disaster reduction and to identify gaps and challenges. The final aim of this action is all people with disabilities to be well informed and motivated towards a culture of earthquake

  1. Building Loss Estimation for Earthquake Insurance Pricing

    NASA Astrophysics Data System (ADS)

    Durukal, E.; Erdik, M.; Sesetyan, K.; Demircioglu, M. B.; Fahjan, Y.; Siyahi, B.

    2005-12-01

    After the 1999 earthquakes in Turkey several changes in the insurance sector took place. A compulsory earthquake insurance scheme was introduced by the government. The reinsurance companies increased their rates. Some even supended operations in the market. And, most important, the insurance companies realized the importance of portfolio analysis in shaping their future market strategies. The paper describes an earthquake loss assessment methodology that can be used for insurance pricing and portfolio loss estimation that is based on our work esperience in the insurance market. The basic ingredients are probabilistic and deterministic regional site dependent earthquake hazard, regional building inventory (and/or portfolio), building vulnerabilities associated with typical construction systems in Turkey and estimations of building replacement costs for different damage levels. Probable maximum and average annualized losses are estimated as the result of analysis. There is a two-level earthquake insurance system in Turkey, the effect of which is incorporated in the algorithm: the national compulsory earthquake insurance scheme and the private earthquake insurance system. To buy private insurance one has to be covered by the national system, that has limited coverage. As a demonstration of the methodology we look at the case of Istanbul and use its building inventory data instead of a portfolio. A state-of-the-art time depent earthquake hazard model that portrays the increased earthquake expectancies in Istanbul is used. Intensity and spectral displacement based vulnerability relationships are incorporated in the analysis. In particular we look at the uncertainty in the loss estimations that arise from the vulnerability relationships, and at the effect of the implemented repair cost ratios.

  2. Statistical tests of simple earthquake cycle models

    USGS Publications Warehouse

    Devries, Phoebe M. R.; Evans, Eileen

    2016-01-01

    A central goal of observing and modeling the earthquake cycle is to forecast when a particular fault may generate an earthquake: a fault late in its earthquake cycle may be more likely to generate an earthquake than a fault early in its earthquake cycle. Models that can explain geodetic observations throughout the entire earthquake cycle may be required to gain a more complete understanding of relevant physics and phenomenology. Previous efforts to develop unified earthquake models for strike-slip faults have largely focused on explaining both preseismic and postseismic geodetic observations available across a few faults in California, Turkey, and Tibet. An alternative approach leverages the global distribution of geodetic and geologic slip rate estimates on strike-slip faults worldwide. Here we use the Kolmogorov-Smirnov test for similarity of distributions to infer, in a statistically rigorous manner, viscoelastic earthquake cycle models that are inconsistent with 15 sets of observations across major strike-slip faults. We reject a large subset of two-layer models incorporating Burgers rheologies at a significance level of α = 0.05 (those with long-term Maxwell viscosities ηM <~ 4.0 × 1019 Pa s and ηM >~ 4.6 × 1020 Pa s) but cannot reject models on the basis of transient Kelvin viscosity ηK. Finally, we examine the implications of these results for the predicted earthquake cycle timing of the 15 faults considered and compare these predictions to the geologic and historical record.

  3. Universal Recurrence Time Statistics of Characteristic Earthquakes

    NASA Astrophysics Data System (ADS)

    Goltz, C.; Turcotte, D. L.; Abaimov, S.; Nadeau, R. M.

    2006-12-01

    Characteristic earthquakes are defined to occur quasi-periodically on major faults. Do recurrence time statistics of such earthquakes follow a particular statistical distribution? If so, which one? The answer is fundamental and has important implications for hazard assessment. The problem cannot be solved by comparing the goodness of statistical fits as the available sequences are too short. The Parkfield sequence of M ≍ 6 earthquakes, one of the most extensive reliable data sets available, has grown to merely seven events with the last earthquake in 2004, for example. Recently, however, advances in seismological monitoring and improved processing methods have unveiled so-called micro-repeaters, micro-earthquakes which recur exactly in the same location on a fault. It seems plausible to regard these earthquakes as a miniature version of the classic characteristic earthquakes. Micro-repeaters are much more frequent than major earthquakes, leading to longer sequences for analysis. Due to their recent discovery, however, available sequences contain less than 20 events at present. In this paper we present results for the analysis of recurrence times for several micro-repeater sequences from Parkfield and adjacent regions. To improve the statistical significance of our findings, we combine several sequences into one by rescaling the individual sets by their respective mean recurrence intervals and Weibull exponents. This novel approach of rescaled combination yields the most extensive data set possible. We find that the resulting statistics can be fitted well by an exponential distribution, confirming the universal applicability of the Weibull distribution to characteristic earthquakes. A similar result is obtained from rescaled combination, however, with regard to the lognormal distribution.

  4. A long source area of the 1906 Colombia-Ecuador earthquake estimated from observed tsunami waveforms

    NASA Astrophysics Data System (ADS)

    Yamanaka, Yusuke; Tanioka, Yuichiro; Shiina, Takahiro

    2017-12-01

    The 1906 Colombia-Ecuador earthquake induced both strong seismic motions and a tsunami, the most destructive earthquake in the history of the Colombia-Ecuador subduction zone. The tsunami propagated across the Pacific Ocean, and its waveforms were observed at tide gauge stations in countries including Panama, Japan, and the USA. This study conducted slip inverse analysis for the 1906 earthquake using these waveforms. A digital dataset of observed tsunami waveforms at the Naos Island (Panama) and Honolulu (USA) tide gauge stations, where the tsunami was clearly observed, was first produced by consulting documents. Next, the two waveforms were applied in an inverse analysis as the target waveform. The results of this analysis indicated that the moment magnitude of the 1906 earthquake ranged from 8.3 to 8.6. Moreover, the dominant slip occurred in the northern part of the assumed source region near the coast of Colombia, where little significant seismicity has occurred, rather than in the southern part. The results also indicated that the source area, with significant slip, covered a long distance, including the southern, central, and northern parts of the region.[Figure not available: see fulltext.

  5. Economic consequences of earthquakes: bridging research and practice with HayWired

    NASA Astrophysics Data System (ADS)

    Wein, A. M.; Kroll, C.

    2016-12-01

    The U.S. Geological Survey partners with organizations and experts to develop multiple hazard scenarios. The HayWired earthquake scenario refers to a rupture of the Hayward fault in the Bay Area of California and addresses the potential chaos related to interconnectedness at many levels: the fault afterslip and aftershocks, interdependencies of lifelines, wired/wireless technology, communities at risk, and ripple effects throughout today's digital economy. The scenario is intended for diverse audiences. HayWired analyses translate earthquake hazards (surface rupture, ground shaking, liquefaction, landslides) into physical engineering and environmental health impacts, and into societal consequences. Damages to life and property and lifeline service disruptions are direct causes of business interruption. Economic models are used to estimate the economic impacts and resilience in the regional economy. The objective of the economic analysis is to inform policy discourse about economic resilience at all three levels of the economy: macro, meso, and micro. Stakeholders include businesses, economic development, and community leaders. Previous scenario analyses indicate the size of an event: large earthquakes and large winter storms are both "big ones" for California. They motivate actions to reduce the losses from fire following earthquake and water supply outages. They show the effect that resilience can have on reducing economic losses. Evaluators find that stakeholders learned the most about the economic consequences.

  6. A teleseismic analysis of the New Brunswick earthquake of January 9, 1982.

    USGS Publications Warehouse

    Choy, G.L.; Boatwright, J.; Dewey, J.W.; Sipkin, S.A.

    1983-01-01

    The analysis of the New Brunswick earthquake of January 9, 1982, has important implications for the evaluation of seismic hazards in eastern North America. Although moderate in size (mb, 5.7), it was well-recorded teleseismically. Source characteristics of this earthquake have been determined from analysis of data that were digitally recorded by the Global Digital Seismography Network. From broadband displacement and velocity records of P waves, we have obtained a dynamic description of the rupture process as well as conventional static properties of the source. The depth of the hypocenter is estimated to be 9km from depth phases. The focal mechanism determined from the broadband data corresponds to predominantly thrust faulting. From the variation in the waveforms the direction of slip is inferred to be updip on a west dipping NNE striking fault plane. The steep dip of the inferred fault plane suggests that the earthquake occurred on a preexisting fault that was at one time a normal fault. From an inversion of body wave pulse durations, the estimated rupture length is 5.5km.-from Authors

  7. The Trembling Earth Before Wenchuan Earthquake: Recognition of Precursory Anomalies through High Frequency Sampling Data of Groundwater

    NASA Astrophysics Data System (ADS)

    Huang, F.

    2017-12-01

    With a magnitude of MS8.0, the 2008 Wenchuan earthquake is classified as one of the "great earthquakes", which are potentially the most destructive, since it occurred at shallow depth close to a highly populated area without prediction, due to no confirmative precursors which were detected from a large amount of newly carried out digital observation data. Scientists who specilize in prediction routine work had been condemned and self-condemned for a long time then. After the pain of defeat passed, scientists have been some thinking to analyze the old observation data in new perspectives from longer temporal process, multiple-disciplinaries, and in different frequency. This presentation will show the preliminary results from groundwater level and temperature observed in 3 wells which distribute along the boundaries of tectonic blocks nearby and far from Wenchuan earthquake rupture.

  8. H. Sapiens Digital: From Digital Immigrants and Digital Natives to Digital Wisdom

    ERIC Educational Resources Information Center

    Prensky, Marc

    2009-01-01

    As we move further into the 21st century, the digital native/digital immigrant paradigm created by Marc Prensky in 2001 is becoming less relevant. In this article, Prensky suggests that we should focus instead on the development of what he calls "digital wisdom." Arguing that digital technology can make us not just smarter but truly wiser, Prensky…

  9. The relationship between earthquake exposure and posttraumatic stress disorder in 2013 Lushan earthquake

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Lu, Yi

    2018-01-01

    The objective of this study is to explore the relationship between earthquake exposure and the incidence of PTSD. A stratification random sample survey was conducted to collect data in the Longmenshan thrust fault after Lushan earthquake three years. We used the Children's Revised Impact of Event Scale (CRIES-13) and the Earthquake Experience Scale. Subjects in this study included 3944 school student survivors in local eleven schools. The prevalence of probable PTSD is relatively higher, when the people was trapped in the earthquake, was injured in the earthquake or have relatives who died in the earthquake. It concluded that researchers need to pay more attention to the children and adolescents. The government should pay more attention to these people and provide more economic support.

  10. Sense of Community and Depressive Symptoms among Older Earthquake Survivors Following the 2008 Earthquake in Chengdu China

    ERIC Educational Resources Information Center

    Li, Yawen; Sun, Fei; He, Xusong; Chan, Kin Sun

    2011-01-01

    This study examined the impact of an earthquake as well as the role of sense of community as a protective factor against depressive symptoms among older Chinese adults who survived an 8.0 magnitude earthquake in 2008. A household survey of a random sample was conducted 3 months after the earthquake and 298 older earthquake survivors participated…

  11. Earthquake hazard assessment after Mexico (1985).

    PubMed

    Degg, M R

    1989-09-01

    The 1985 Mexican earthquake ranks foremost amongst the major earthquake disasters of the twentieth century. One of the few positive aspects of the disaster is that it provided massive quantities of data that would otherwise have been unobtainable. Every opportunity should be taken to incorporate the findings from these data in earthquake hazard assessments. The purpose of this paper is to provide a succinct summary of some of the more important lessons from Mexico. It stems from detailed field investigations, and subsequent analyses, conducted by the author on the behalf of reinsurance companies.

  12. SITE AMPLIFICATION OF EARTHQUAKE GROUND MOTION.

    USGS Publications Warehouse

    Hays, Walter W.

    1986-01-01

    When analyzing the patterns of damage in an earthquake, physical parameters of the total earthquake-site-structure system are correlated with the damage. Soil-structure interaction, the cause of damage in many earthquakes, involves the frequency-dependent response of both the soil-rock column and the structure. The response of the soil-rock column (called site amplification) is controversial because soil has strain-dependent properties that affect the way the soil column filters the input body and surface seismic waves, modifying the amplitude and phase spectra and the duration of the surface ground motion.

  13. PAGER - Rapid Assessment of an Earthquake's Impact

    USGS Publications Warehouse

    Earle, Paul S.; Wald, David J.

    2007-01-01

    PAGER (Prompt Assessment of Global Earthquakes for Response) is an automated system to rapidly assess the number of people and regions exposed to severe shaking by an earthquake, and inform emergency responders, government agencies, and the media to the scope of the potential disaster. PAGER monitors the U.S. Geological Survey?s near real-time U.S. and global earthquake detections and automatically identifies events that are of societal importance, well in advance of ground-truth or news accounts.

  14. The southern California uplift and associated earthquakes

    USGS Publications Warehouse

    Castle, R.O.; Bernknopf, R.L.

    1996-01-01

    Southern California earthquakes ??? M5.5 during the period 1955/01/01-1994/01/17 were concentrated along or adjacent to the south flank of the southern California uplift, as defined both at its culmination and following its partial collapse. Spatial clustering of these earthquakes within three more-or-less distinct groups suggests either gaps along the south flank that were previously filled or are yet to be filled. Nearly all of the indicated earthquakes accompanied or followed partial collapse of the uplift, and seismic activity within this regime seems to have been increasing through at least 1994/01/17. Copyright 1996 by the American Geophysical Union.

  15. Are landslides in the New Madrid Seismic Zone the result of the 1811-1812 earthquake sequence or multiple prehistoric earthquakes?

    NASA Astrophysics Data System (ADS)

    Gold, Ryan; Williams, Robert; Jibson, Randall

    2014-05-01

    Previous research indicates that deep translational and rotational landslides along the bluffs east of the Mississippi River in western Tennessee were triggered by the M7-8 1811-1812 New Madrid earthquake sequence. Analysis of recently acquired airborne LiDAR data suggests the possibility of multiple generations of landslides, possibly triggered by older, similar magnitude earthquake sequences, which paleoliquifaction studies show occurred circa 1450 and about 900 A.D. Using these LiDAR data, we have remapped recent landslides along two sections of the bluffs: a northern section near Reelfoot Lake and a southern section near Meeman-Shelby State Park (20 km north of Memphis, Tennessee). The bare-earth, digital-elevation models derived from these LiDAR data have a resolution of 0.5 m and reveal valuable details of topography given the region's dense forest canopy. Our mapping confirms much of the previous landslide mapping, refutes a few previously mapped landslides, and reveals new, undetected landslides. Importantly, we observe that the landslide deposits in the Reelfoot region are characterized by rotated blocks with sharp uphill-facing scarps and steep headwall scarps, indicating youthful, relatively recent movement. In comparison, landslide deposits near Meeman-Shelby are muted in appearance, with headwall scarps and rotated blocks that are extensively dissected by gullies, indicating they might be an older generation of landslides. Because of these differences in morphology, we hypothesize that the landslides near Reelfoot Lake were triggered by the 1811-1812 earthquake sequence and that landslides near Meeman-Shelby resulted from shaking associated with earlier earthquake sequences. To test this hypothesis, we will evaluate differences in bluff height, local geology, vegetation, and proximity to known seismic sources. Furthermore, planned fieldwork will help evaluate whether the observed landslide displacements occurred in single earthquakes or if they might

  16. Earthquake catalog for estimation of maximum earthquake magnitude, Central and Eastern United States: Part A, Prehistoric earthquakes

    USGS Publications Warehouse

    Wheeler, Russell L.

    2014-01-01

    Computation of probabilistic earthquake hazard requires an estimate of Mmax, the maximum earthquake magnitude thought to be possible within a specified geographic region. This report is Part A of an Open-File Report that describes the construction of a global catalog of moderate to large earthquakes, from which one can estimate Mmax for most of the Central and Eastern United States and adjacent Canada. The catalog and Mmax estimates derived from it were used in the 2014 edition of the U.S. Geological Survey national seismic-hazard maps. This Part A discusses prehistoric earthquakes that occurred in eastern North America, northwestern Europe, and Australia, whereas a separate Part B deals with historical events.

  17. The SCEC TeraShake Earthquake Simulation

    NASA Astrophysics Data System (ADS)

    Minster, J.; Olsen, K. B.; Moore, R.; Day, S.; Maechling, P.; Jordan, T.; Faerman, M.; Cui, Y.; Ely, G.; Hu, Y.; Shkoller, B.; Marcinkovich, C.; Bielak, J.; Okaya, D.; Archuleta, R.; Wilkins-Diehr, N.; Cutchin, S.; Chourasia, A.; Kremenek, G.; Jagatheesan, A.; Brieger, L.; Majundar, A.; Chukkapalli, G.; Xin, Q.; Moore, R.; Banister, B.; Thorp, D.; Kovatch, P.; Diegel, L.; Sherwin, T.; Jordan, C.; Thiebaux, M.; Lopez, J.

    2004-12-01

    The southern portion of the San Andreas fault, between Cajon Creek and Bombay Beach has not seen a major event since 1690, and has therefore accumulated a slip deficit of 5-6 m. The potential for this portion of the fault to rupture in a single M7.7 event is a major component of seismic hazard in southern California and northern Mexico. TeraShake is a large-scale finite-difference (fourth-order) simulation of such an event based on Olsen's Anelastic Wave Propagation Model (AWM) code, and conducted in the context of the Southern California Earthquake Center Community Modeling Environment (CME). The fault geometry is taken from the 2002 USGS National Hazard Maps. The kinematic slip function is transported and scaled from published inversions for the 2002 Denali (M7.9) earthquake. The three-dimensional crustal structure is the SCEC Community Velocity model. The 600km x 300km x 80km simulation domain extends from the Ventura Basin and Tehachapi region to the north and to Mexicali and Tijuana to the south. It includes all major population centers in southern California, and is modeled at 200m resolution using a rectangular, 1.8 giganode, 3000 x 1500 x 400 mesh. The simulated duration is 200 seconds, with a temporal resolution of 0.01seconds, maximum frequency of 0.5Hz, for a total of 20,000 time steps. The simulation is planned to run at the San Diego Supercomputer Center (SDSC) on 240 processors of the IBM Power4, DataStar machine. Validation runs conducted at one sixteenth (4D) resolution have shown that this is the optimal configuration in the trade-off between computational and I/O demands. The full run will consume about 18,000 CPU.hours. Each time step produces a 21.6GByte mesh snapshot of the entire ground motion velocity vectors. A 4D wavefield containing 2,000 time steps, amounting to 43 Tbytes of data, will be stored at SDSC. Surface data will be archived for every time step for synthetic seismogram engineering analysis, totaling 1 Tbyte. The data will be

  18. Nowcasting Earthquakes: A Comparison of Induced Earthquakes in Oklahoma and at the Geysers, California

    NASA Astrophysics Data System (ADS)

    Luginbuhl, Molly; Rundle, John B.; Hawkins, Angela; Turcotte, Donald L.

    2018-01-01

    Nowcasting is a new method of statistically classifying seismicity and seismic risk (Rundle et al. 2016). In this paper, the method is applied to the induced seismicity at the Geysers geothermal region in California and the induced seismicity due to fluid injection in Oklahoma. Nowcasting utilizes the catalogs of seismicity in these regions. Two earthquake magnitudes are selected, one large say M_{λ } ≥ 4, and one small say M_{σ } ≥ 2. The method utilizes the number of small earthquakes that occurs between pairs of large earthquakes. The cumulative probability distribution of these values is obtained. The earthquake potential score (EPS) is defined by the number of small earthquakes that has occurred since the last large earthquake, the point where this number falls on the cumulative probability distribution of interevent counts defines the EPS. A major advantage of nowcasting is that it utilizes "natural time", earthquake counts, between events rather than clock time. Thus, it is not necessary to decluster aftershocks and the results are applicable if the level of induced seismicity varies in time. The application of natural time to the accumulation of the seismic hazard depends on the applicability of Gutenberg-Richter (GR) scaling. The increasing number of small earthquakes that occur after a large earthquake can be scaled to give the risk of a large earthquake occurring. To illustrate our approach, we utilize the number of M_{σ } ≥ 2.75 earthquakes in Oklahoma to nowcast the number of M_{λ } ≥ 4.0 earthquakes in Oklahoma. The applicability of the scaling is illustrated during the rapid build-up of injection-induced seismicity between 2012 and 2016, and the subsequent reduction in seismicity associated with a reduction in fluid injections. The same method is applied to the geothermal-induced seismicity at the Geysers, California, for comparison.

  19. The initial subevent of the 1994 Northridge, California, earthquake: Is earthquake size predictable?

    USGS Publications Warehouse

    Kilb, Debi; Gomberg, J.

    1999-01-01

    We examine the initial subevent (ISE) of the M?? 6.7, 1994 Northridge, California, earthquake in order to discriminate between two end-member rupture initiation models: the 'preslip' and 'cascade' models. Final earthquake size may be predictable from an ISE's seismic signature in the preslip model but not in the cascade model. In the cascade model ISEs are simply small earthquakes that can be described as purely dynamic ruptures. In this model a large earthquake is triggered by smaller earthquakes; there is no size scaling between triggering and triggered events and a variety of stress transfer mechanisms are possible. Alternatively, in the preslip model, a large earthquake nucleates as an aseismically slipping patch in which the patch dimension grows and scales with the earthquake's ultimate size; the byproduct of this loading process is the ISE. In this model, the duration of the ISE signal scales with the ultimate size of the earthquake, suggesting that nucleation and earthquake size are determined by a more predictable, measurable, and organized process. To distinguish between these two end-member models we use short period seismograms recorded by the Southern California Seismic Network. We address questions regarding the similarity in hypocenter locations and focal mechanisms of the ISE and the mainshock. We also compare the ISE's waveform characteristics to those of small earthquakes and to the beginnings of earthquakes with a range of magnitudes. We find that the focal mechanisms of the ISE and mainshock are indistinguishable, and both events may have nucleated on and ruptured the same fault plane. These results satisfy the requirements for both models and thus do not discriminate between them. However, further tests show the ISE's waveform characteristics are similar to those of typical small earthquakes in the vicinity and more importantly, do not scale with the mainshock magnitude. These results are more consistent with the cascade model.

  20. Time-dependent earthquake probabilities

    USGS Publications Warehouse

    Gomberg, J.; Belardinelli, M.E.; Cocco, M.; Reasenberg, P.

    2005-01-01

    We have attempted to provide a careful examination of a class of approaches for estimating the conditional probability of failure of a single large earthquake, particularly approaches that account for static stress perturbations to tectonic loading as in the approaches of Stein et al. (1997) and Hardebeck (2004). We have loading as in the framework based on a simple, generalized rate change formulation and applied it to these two approaches to show how they relate to one another. We also have attempted to show the connection between models of seismicity rate changes applied to (1) populations of independent faults as in background and aftershock seismicity and (2) changes in estimates of the conditional probability of failures of different members of a the notion of failure rate corresponds to successive failures of different members of a population of faults. The latter application requires specification of some probability distribution (density function of PDF) that describes some population of potential recurrence times. This PDF may reflect our imperfect knowledge of when past earthquakes have occurred on a fault (epistemic uncertainty), the true natural variability in failure times, or some combination of both. We suggest two end-member conceptual single-fault models that may explain natural variability in recurrence times and suggest how they might be distinguished observationally. When viewed deterministically, these single-fault patch models differ significantly in their physical attributes, and when faults are immature, they differ in their responses to stress perturbations. Estimates of conditional failure probabilities effectively integrate over a range of possible deterministic fault models, usually with ranges that correspond to mature faults. Thus conditional failure probability estimates usually should not differ significantly for these models. Copyright 2005 by the American Geophysical Union.

  1. Digital Sensor Technology

    SciTech Connect

    Ted Quinn; Jerry Mauck; Richard Bockhorst

    The nuclear industry has been slow to incorporate digital sensor technology into nuclear plant designs due to concerns with digital qualification issues. However, the benefits of digital sensor technology for nuclear plant instrumentation are substantial in terms of accuracy, reliability, availability, and maintainability. This report demonstrates these benefits in direct comparisons of digital and analog sensor applications. It also addresses the qualification issues that must be addressed in the application of digital sensor technology.

  2. The 1985 central chile earthquake: a repeat of previous great earthquakes in the region?

    PubMed

    Comte, D; Eisenberg, A; Lorca, E; Pardo, M; Ponce, L; Saragoni, R; Singh, S K; Suárez, G

    1986-07-25

    A great earthquake (surface-wave magnitude, 7.8) occurred along the coast of central Chile on 3 March 1985, causing heavy damage to coastal towns. Intense foreshock activity near the epicenter of the main shock occurred for 11 days before the earthquake. The aftershocks of the 1985 earthquake define a rupture area of 170 by 110 square kilometers. The earthquake was forecast on the basis of the nearly constant repeat time (83 +/- 9 years) of great earthquakes in this region. An analysis of previous earthquakes suggests that the rupture lengths of great shocks in the region vary by a factor of about 3. The nearly constant repeat time and variable rupture lengths cannot be reconciled with time- or slip-predictable models of earthquake recurrence. The great earthquakes in the region seem to involve a variable rupture mode and yet, for unknown reasons, remain periodic. Historical data suggest that the region south of the 1985 rupture zone should now be considered a gap of high seismic potential that may rupture in a great earthquake in the next few tens of years.

  3. GPS Technologies as a Tool to Detect the Pre-Earthquake Signals Associated with Strong Earthquakes

    NASA Astrophysics Data System (ADS)

    Pulinets, S. A.; Krankowski, A.; Hernandez-Pajares, M.; Liu, J. Y. G.; Hattori, K.; Davidenko, D.; Ouzounov, D.

    2015-12-01

    The existence of ionospheric anomalies before earthquakes is now widely accepted. These phenomena started to be considered by GPS community to mitigate the GPS signal degradation over the territories of the earthquake preparation. The question is still open if they could be useful for seismology and for short-term earthquake forecast. More than decade of intensive studies proved that ionospheric anomalies registered before earthquakes are initiated by processes in the boundary layer of atmosphere over earthquake preparation zone and are induced in the ionosphere by electromagnetic coupling through the Global Electric Circuit. Multiparameter approach based on the Lithosphere-Atmosphere-Ionosphere Coupling model demonstrated that earthquake forecast is possible only if we consider the final stage of earthquake preparation in the multidimensional space where every dimension is one from many precursors in ensemble, and they are synergistically connected. We demonstrate approaches developed in different countries (Russia, Taiwan, Japan, Spain, and Poland) within the framework of the ISSI and ESA projects) to identify the ionospheric precursors. They are also useful to determine the all three parameters necessary for the earthquake forecast: impending earthquake epicenter position, expectation time and magnitude. These parameters are calculated using different technologies of GPS signal processing: time series, correlation, spectral analysis, ionospheric tomography, wave propagation, etc. Obtained results from different teams demonstrate the high level of statistical significance and physical justification what gives us reason to suggest these methodologies for practical validation.

  4. Perception of earthquake risk in Taiwan: effects of gender and past earthquake experience.

    PubMed

    Kung, Yi-Wen; Chen, Sue-Huei

    2012-09-01

    This study explored how individuals in Taiwan perceive the risk of earthquake and the relationship of past earthquake experience and gender to risk perception. Participants (n= 1,405), including earthquake survivors and those in the general population without prior direct earthquake exposure, were selected and interviewed through a computer-assisted telephone interviewing procedure using a random sampling and stratification method covering all 24 regions of Taiwan. A factor analysis of the interview data yielded a two-factor structure of risk perception in regard to earthquake. The first factor, "personal impact," encompassed perception of threat and fear related to earthquakes. The second factor, "controllability," encompassed a sense of efficacy of self-protection in regard to earthquakes. The findings indicated prior earthquake survivors and females reported higher scores on the personal impact factor than males and those with no prior direct earthquake experience, although there were no group differences on the controllability factor. The findings support that risk perception has multiple components, and suggest that past experience (survivor status) and gender (female) affect the perception of risk. Exploration of potential contributions of other demographic factors such as age, education, and marital status to personal impact, especially for females and survivors, is discussed. Future research on and intervention program with regard to risk perception are suggested accordingly. © 2012 Society for Risk Analysis.

  5. Impact of earthquakes on sex ratio at birth: Eastern Marmara earthquakes

    PubMed Central

    Doğer, Emek; Çakıroğlu, Yiğit; Köpük, Şule Yıldırım; Ceylan, Yasin; Şimşek, Hayal Uzelli; Çalışkan, Eray

    2013-01-01

    Objective: Previous reports suggest that maternal exposure to acute stress related to earthquakes affects the sex ratio at birth. Our aim was to examine the change in sex ratio at birth after Eastern Marmara earthquake disasters. Material and Methods: This study was performed using the official birth statistics from January 1997 to December 2002 – before and after 17 August 1999, the date of the Golcuk Earthquake – supplied from the Turkey Statistics Institute. The secondary sex ratio was expressed as the male proportion at birth, and the ratio of both affected and unaffected areas were calculated and compared on a monthly basis using data from gender with using the Chi-square test. Results: We observed significant decreases in the secondary sex ratio in the 4th and 8th months following an earthquake in the affected region compared to the unaffected region (p= 0.001 and p= 0.024). In the earthquake region, the decrease observed in the secondary sex ratio during the 8th month after an earthquake was specific to the period after the earthquake. Conclusion: Our study indicated a significant reduction in the secondary sex ratio after an earthquake. With these findings, events that cause sudden intense stress such as earthquakes can have an effect on the sex ratio at birth. PMID:24592082

  6. Japanese earthquake predictability experiment with multiple runs before and after the 2011 Tohoku-oki earthquake

    NASA Astrophysics Data System (ADS)

    Hirata, N.; Tsuruoka, H.; Yokoi, S.

    2011-12-01

    The current Japanese national earthquake prediction program emphasizes the importance of modeling as well as monitoring for a sound scientific development of earthquake prediction research. One major focus of the current program is to move toward creating testable earthquake forecast models. For this purpose, in 2009 we joined the Collaboratory for the Study of Earthquake Predictability (CSEP) and installed, through an international collaboration, the CSEP Testing Centre, an infrastructure to encourage researchers to develop testable models for Japan. We started Japanese earthquake predictability experiment on November 1, 2009. The experiment consists of 12 categories, with 4 testing classes with different time spans (1 day, 3 months, 1 year and 3 years) and 3 testing regions called 'All Japan,' 'Mainland,' and 'Kanto.' A total of 160 models, as of August 2013, were submitted, and are currently under the CSEP official suite of tests for evaluating the performance of forecasts. We will present results of prospective forecast and testing for periods before and after the 2011 Tohoku-oki earthquake. Because a seismic activity has changed dramatically since the 2011 event, performances of models have been affected very much. In addition, as there is the problem of authorized catalogue related to the completeness magnitude, most models did not pass the CSEP consistency tests. Also, we will discuss the retrospective earthquake forecast experiments for aftershocks of the 2011 Tohoku-oki earthquake. Our aim is to describe what has turned out to be the first occasion for setting up a research environment for rigorous earthquake forecasting in Japan.

  7. Japanese earthquake predictability experiment with multiple runs before and after the 2011 Tohoku-oki earthquake

    NASA Astrophysics Data System (ADS)

    Hirata, N.; Tsuruoka, H.; Yokoi, S.

    2013-12-01

    The current Japanese national earthquake prediction program emphasizes the importance of modeling as well as monitoring for a sound scientific development of earthquake prediction research. One major focus of the current program is to move toward creating testable earthquake forecast models. For this purpose, in 2009 we joined the Collaboratory for the Study of Earthquake Predictability (CSEP) and installed, through an international collaboration, the CSEP Testing Centre, an infrastructure to encourage researchers to develop testable models for Japan. We started Japanese earthquake predictability experiment on November 1, 2009. The experiment consists of 12 categories, with 4 testing classes with different time spans (1 day, 3 months, 1 year and 3 years) and 3 testing regions called 'All Japan,' 'Mainland,' and 'Kanto.' A total of 160 models, as of August 2013, were submitted, and are currently under the CSEP official suite of tests for evaluating the performance of forecasts. We will present results of prospective forecast and testing for periods before and after the 2011 Tohoku-oki earthquake. Because a seismic activity has changed dramatically since the 2011 event, performances of models have been affected very much. In addition, as there is the problem of authorized catalogue related to the completeness magnitude, most models did not pass the CSEP consistency tests. Also, we will discuss the retrospective earthquake forecast experiments for aftershocks of the 2011 Tohoku-oki earthquake. Our aim is to describe what has turned out to be the first occasion for setting up a research environment for rigorous earthquake forecasting in Japan.

  8. Earthquake Damage Assessment Using Objective Image Segmentation: A Case Study of 2010 Haiti Earthquake

    NASA Technical Reports Server (NTRS)

    Oommen, Thomas; Rebbapragada, Umaa; Cerminaro, Daniel

    2012-01-01

    In this study, we perform a case study on imagery from the Haiti earthquake that evaluates a novel object-based approach for characterizing earthquake induced surface effects of liquefaction against a traditional pixel based change technique. Our technique, which combines object-oriented change detection with discriminant/categorical functions, shows the power of distinguishing earthquake-induced surface effects from changes in buildings using the object properties concavity, convexity, orthogonality and rectangularity. Our results suggest that object-based analysis holds promise in automatically extracting earthquake-induced damages from high-resolution aerial/satellite imagery.

  9. Crustal earthquake triggering by pre-historic great earthquakes on subduction zone thrusts

    USGS Publications Warehouse

    Sherrod, Brian; Gomberg, Joan

    2014-01-01

    Triggering of earthquakes on upper plate faults during and shortly after recent great (M>8.0) subduction thrust earthquakes raises concerns about earthquake triggering following Cascadia subduction zone earthquakes. Of particular regard to Cascadia was the previously noted, but only qualitatively identified, clustering of M>~6.5 crustal earthquakes in the Puget Sound region between about 1200–900 cal yr B.P. and the possibility that this was triggered by a great Cascadia thrust subduction thrust earthquake, and therefore portends future such clusters. We confirm quantitatively the extraordinary nature of the Puget Sound region crustal earthquake clustering between 1200–900 cal yr B.P., at least over the last 16,000. We conclude that this cluster was not triggered by the penultimate, and possibly full-margin, great Cascadia subduction thrust earthquake. However, we also show that the paleoseismic record for Cascadia is consistent with conclusions of our companion study of the global modern record outside Cascadia, that M>8.6 subduction thrust events have a high probability of triggering at least one or more M>~6.5 crustal earthquakes.

  10. Deep crustal earthquakes associated with continental rifts

    NASA Astrophysics Data System (ADS)

    Doser, Diane I.; Yarwood, Dennis R.

    1994-01-01

    Deep (> 20 km) crustal earthquakes have occurred within or along the margins of at least four continental rift zones. The largest of these deep crustal earthquakes ( M ⩾ 5.0) have strike-slip or oblique-slip mechanisms with T-axes oriented similarly to those associated with shallow normal faulting within the rift zones. The majority of deep crustal earthquakes occur along the rift margins in regions that have cooler, thicker crust. Several deep crustal events, however, occur in regions of high heat flow. These regions also appear to be regions of high strain, a factor that could account for the observed depths. We believe the deep crustal earthquakes represent either the relative motion of rift zones with respect to adjacent stable regions or the propagation of rifting into stable regions.

  11. California Earthquake Residual Transportation Capability Study

    DOT National Transportation Integrated Search

    1983-12-01

    This report addresses the ability of transportation facilities in California to survive four postulated earthquakes that are based on historical events. The survival of highways, railroads, ports, airports, and pipelines is investigated following ind...

  12. Earthquake Damping Device for Steel Frame

    NASA Astrophysics Data System (ADS)

    Zamri Ramli, Mohd; Delfy, Dezoura; Adnan, Azlan; Torman, Zaida

    2018-04-01

    Structures such as buildings, bridges and towers are prone to collapse when natural phenomena like earthquake occurred. Therefore, many design codes are reviewed and new technologies are introduced to resist earthquake energy especially on building to avoid collapse. The tuned mass damper is one of the earthquake reduction products introduced on structures to minimise the earthquake effect. This study aims to analyse the effectiveness of tuned mass damper by experimental works and finite element modelling. The comparisons are made between these two models under harmonic excitation. Based on the result, it is proven that installing tuned mass damper will reduce the dynamic response of the frame but only in several input frequencies. At the highest input frequency applied, the tuned mass damper failed to reduce the responses. In conclusion, in order to use a proper design of damper, detailed analysis must be carried out to have sufficient design based on the location of the structures with specific ground accelerations.

  13. Shallow moonquakes - How they compare with earthquakes

    NASA Technical Reports Server (NTRS)

    Nakamura, Y.

    1980-01-01

    Of three types of moonquakes strong enough to be detectable at large distances - deep moonquakes, meteoroid impacts and shallow moonquakes - only shallow moonquakes are similar in nature to earthquakes. A comparison of various characteristics of moonquakes with those of earthquakes indeed shows a remarkable similarity between shallow moonquakes and intraplate earthquakes: (1) their occurrences are not controlled by tides; (2) they appear to occur in locations where there is evidence of structural weaknesses; (3) the relative abundances of small and large quakes (b-values) are similar, suggesting similar mechanisms; and (4) even the levels of activity may be close. The shallow moonquakes may be quite comparable in nature to intraplate earthquakes, and they may be of similar origin.

  14. Earthquake prediction; new studies yield promising results

    USGS Publications Warehouse

    Robinson, R.

    1974-01-01

    On Agust 3, 1973, a small earthquake (magnitude 2.5) occurred near Blue Mountain Lake in the Adirondack region of northern New York State. This seemingly unimportant event was of great significance, however, because it was predicted. Seismologsits at the Lamont-Doherty geologcal Observatory of Columbia University accurately foretold the time, place, and magnitude of the event. Their prediction was based on certain pre-earthquake processes that are best explained by a hypothesis known as "dilatancy," a concept that has injected new life and direction into the science of earthquake prediction. Although much mroe reserach must be accomplished before we can expect to predict potentially damaging earthquakes with any degree of consistency, results such as this indicate that we are on a promising road. 

  15. The aftershock signature of supershear earthquakes.

    PubMed

    Bouchon, Michel; Karabulut, Hayrullah

    2008-06-06

    Recent studies show that earthquake faults may rupture at speeds exceeding the shear wave velocity of rocks. This supershear rupture produces in the ground a seismic shock wave similar to the sonic boom produced by a supersonic airplane. This shock wave may increase the destruction caused by the earthquake. We report that supershear earthquakes are characterized by a specific pattern of aftershocks: The fault plane itself is remarkably quiet whereas aftershocks cluster off the fault, on secondary structures that are activated by the supershear rupture. The post-earthquake quiescence of the fault shows that friction is relatively uniform over supershear segments, whereas the activation of off-fault structures is explained by the shock wave radiation, which produces high stresses over a wide zone surrounding the fault.

  16. The enigmatic Bala earthquake of 1974

    NASA Astrophysics Data System (ADS)

    Musson, R. M. W.

    2006-10-01

    The earthquake that shook most of North Wales on the night of 23 January 1974 appears unremarkable from its entry in the UK earthquake catalogue. With a magnitude of 3.5 ML it represents the size of earthquake to be expected in the UK with a return period of about one year. However, the prominent atmospheric lights observed at the time of the shock led to speculation that an aircraft had crashed, and search-and-rescue teams were deployed. Since nothing was discovered, it was concluded that a meteorite was responsible; more imaginative members of the public decided (and still believe) that a UFO had crashed. In this paper the record of events is set out, and the nature of the earthquake is discussed with reference to its geological setting.

  17. Coping with earthquakes induced by fluid injection

    USGS Publications Warehouse

    McGarr, Arthur F.; Bekins, Barbara; Burkardt, Nina; Dewey, James W.; Earle, Paul S.; Ellsworth, William L.; Ge, Shemin; Hickman, Stephen H.; Holland, Austin F.; Majer, Ernest; Rubinstein, Justin L.; Sheehan, Anne

    2015-01-01

    Large areas of the United States long considered geologically stable with little or no detected seismicity have recently become seismically active. The increase in earthquake activity began in the mid-continent starting in 2001 (1) and has continued to rise. In 2014, the rate of occurrence of earthquakes with magnitudes (M) of 3 and greater in Oklahoma exceeded that in California (see the figure). This elevated activity includes larger earthquakes, several with M > 5, that have caused significant damage (2, 3). To a large extent, the increasing rate of earthquakes in the mid-continent is due to fluid-injection activities used in modern energy production (1, 4, 5). We explore potential avenues for mitigating effects of induced seismicity. Although the United States is our focus here, Canada, China, the UK, and others confront similar problems associated with oil and gas production, whereas quakes induced by geothermal activities affect Switzerland, Germany, and others.

  18. Sea-level changes before large earthquakes

    USGS Publications Warehouse

    Wyss, M.

    1978-01-01

    Changes in sea level have long been used as a measure of local uplift and subsidence associated with large earthquakes. For instance, in 1835, the British naturalist Charles Darwin observed that sea level dropped by 2.7 meters during the large earthquake in Concepcion, CHile. From this piece of evidence and the terraces along the beach that he saw, Darwin concluded that the Andes had grown to their present height through earthquakes. Much more recently, George Plafker and James C. Savage of the U.S Geological Survey have shown, from barnacle lines, that the great 1960 Chile and the 1964 Alaska earthquakes caused several meters of vertical displacement of the shoreline. 

  19. Mega-earthquakes rupture flat megathrusts.

    PubMed

    Bletery, Quentin; Thomas, Amanda M; Rempel, Alan W; Karlstrom, Leif; Sladen, Anthony; De Barros, Louis

    2016-11-25

    The 2004 Sumatra-Andaman and 2011 Tohoku-Oki earthquakes highlighted gaps in our understanding of mega-earthquake rupture processes and the factors controlling their global distribution: A fast convergence rate and young buoyant lithosphere are not required to produce mega-earthquakes. We calculated the curvature along the major subduction zones of the world, showing that mega-earthquakes preferentially rupture flat (low-curvature) interfaces. A simplified analytic model demonstrates that heterogeneity in shear strength increases with curvature. Shear strength on flat megathrusts is more homogeneous, and hence more likely to be exceeded simultaneously over large areas, than on highly curved faults. Copyright © 2016, American Association for the Advancement of Science.

  20. Computer systems for automatic earthquake detection

    USGS Publications Warehouse

    Stewart, S.W.

    1974-01-01

    U.S Geological Survey seismologists in Menlo park, California, are utilizing the speed, reliability, and efficiency of minicomputers to monitor seismograph stations and to automatically detect earthquakes. An earthquake detection computer system, believed to be the only one of its kind in operation, automatically reports about 90 percent of all local earthquakes recorded by a network of over 100 central California seismograph stations. The system also monitors the stations for signs of malfunction or abnormal operation. Before the automatic system was put in operation, all of the earthquakes recorded had to be detected by manually searching the records, a time-consuming process. With the automatic detection system, the stations are efficiently monitored continuously. 

  1. Satellite Radar Measures Tohoku, Japan Earthquake

    NASA Image and Video Library

    2011-04-01

    This radar image, called a coseismic interferogram, using satellite data from the European Space Agency Envisat depicts ground displacements resulting from the March 11, 2011, magnitude 9.0 Tohoku earthquake in Japan.

  2. Earthquake hazards in the Alaska transportation corridors

    DOT National Transportation Integrated Search

    1983-03-01

    Based on observations made by modern seismographic networks since 1967, and taking into consideration historical records of large Alaskan earthquakes in the past, it is judged that the hazards faced by transportation corridors in different areas of t...

  3. Baja Earthquake, Radar Image and Colored Height

    NASA Image and Video Library

    2010-04-05

    The topography surrounding the Laguna Salada Fault in the Mexican state of Baja, California, is shown in this perspective view with data from NASA Shuttle Radar Topography Mission where a 7.2 earthquake struck on April 4, 2010.

  4. Strong ground motion prediction using virtual earthquakes.

    PubMed

    Denolle, M A; Dunham, E M; Prieto, G A; Beroza, G C

    2014-01-24

    Sedimentary basins increase the damaging effects of earthquakes by trapping and amplifying seismic waves. Simulations of seismic wave propagation in sedimentary basins capture this effect; however, there exists no method to validate these results for earthquakes that have not yet occurred. We present a new approach for ground motion prediction that uses the ambient seismic field. We apply our method to a suite of magnitude 7 scenario earthquakes on the southern San Andreas fault and compare our ground motion predictions with simulations. Both methods find strong amplification and coupling of source and structure effects, but they predict substantially different shaking patterns across the Los Angeles Basin. The virtual earthquake approach provides a new approach for predicting long-period strong ground motion.

  5. Earthquake in Hindu Kush Region, Afghanistan

    NASA Image and Video Library

    2015-10-27

    On Oct. 26, 2015, NASA Terra spacecraft acquired this image of northeastern Afghanistan where a magnitude 7.5 earthquake struck the Hindu Kush region. The earthquake's epicenter was at a depth of 130 miles (210 kilometers), on a probable shallowly dipping thrust fault. At this location, the Indian subcontinent moves northward and collides with Eurasia, subducting under the Asian continent, and raising the highest mountains in the world. This type of earthquake is common in the area: a similar earthquake occurred 13 years ago about 12 miles (20 kilometers) away. This perspective image from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft, looking southwest, shows the hypocenter with a star. The image was acquired July 8, 2015, and is located near 36.4 degrees north, 70.7 degrees east. http://photojournal.jpl.nasa.gov/catalog/PIA20035

  6. Safety and survival in an earthquake

    USGS Publications Warehouse

    ,

    1969-01-01

    Many earth scientists in this country and abroad are focusing their studies on the search for means of predicting impending earthquakes, but, as yet, an accurate prediction of the time and place of such an event cannot be made. From past experience, however, one can assume that earthquakes will continue to harass mankind and that they will occur most frequently in the areas where they have been relatively common in the past. In the United States, earthquakes can be expected to occur most frequently in the western states, particularly in Alaska, California, Washington, Oregon, Nevada, Utah, and Montana. The danger, however, is not confined to any one part of the country; major earthquakes have occurred at widely scattered locations.

  7. Supercomputing meets seismology in earthquake exhibit

    ScienceCinema

    Blackwell, Matt; Rodger, Arthur; Kennedy, Tom

    2018-02-14

    When the California Academy of Sciences created the "Earthquake: Evidence of a Restless Planet" exhibit, they called on Lawrence Livermore to help combine seismic research with the latest data-driven visualization techniques. The outcome is a series of striking visualizations of earthquakes, tsunamis and tectonic plate evolution. Seismic-wave research is a core competency at Livermore. While most often associated with earthquakes, the research has many other applications of national interest, such as nuclear explosion monitoring, explosion forensics, energy exploration, and seismic acoustics. For the Academy effort, Livermore researchers simulated the San Andreas and Hayward fault events at high resolutions. Such calculations require significant computational resources. To simulate the 1906 earthquake, for instance, visualizing 125 seconds of ground motion required over 1 billion grid points, 10,000 time steps, and 7.5 hours of processor time on 2,048 cores of Livermore's Sierra machine.

  8. Lisbon 1755, a multiple-rupture earthquake

    NASA Astrophysics Data System (ADS)

    Fonseca, J. F. B. D.

    2017-12-01

    The Lisbon earthquake of 1755 poses a challenge to seismic hazard assessment. Reports pointing to MMI 8 or above at distances of the order of 500km led to magnitude estimates near M9 in classic studies. A refined analysis of the coeval sources lowered the estimates to 8.7 (Johnston, 1998) and 8.5 (Martinez-Solares, 2004). I posit that even these lower magnitude values reflect the combined effect of multiple ruptures. Attempts to identify a single source capable of explaining the damage reports with published ground motion models did not gather consensus and, compounding the challenge, the analysis of tsunami traveltimes has led to disparate source models, sometimes separated by a few hundred kilometers. From this viewpoint, the most credible source would combine a sub-set of the multiple active structures identifiable in SW Iberia. No individual moment magnitude needs to be above M8.1, thus rendering the search for candidate structures less challenging. The possible combinations of active structures should be ranked as a function of their explaining power, for macroseismic intensities and tsunami traveltimes taken together. I argue that the Lisbon 1755 earthquake is an example of a distinct class of intraplate earthquake previously unrecognized, of which the Indian Ocean earthquake of 2012 is the first instrumentally recorded example, showing space and time correlation over scales of the orders of a few hundred km and a few minutes. Other examples may exist in the historical record, such as the M8 1556 Shaanxi earthquake, with an unusually large damage footprint (MMI equal or above 6 in 10 provinces; 830000 fatalities). The ability to trigger seismicity globally, observed after the 2012 Indian Ocean earthquake, may be a characteristic of this type of event: occurrences in Massachussets (M5.9 Cape Ann earthquake on 18/11/1755), Morocco (M6.5 Fez earthquake on 27/11/1755) and Germany (M6.1 Duren earthquake, on 18/02/1756) had in all likelyhood a causal link to the

  9. Unusual ionospheric variations before the strong Auckland Islands, New Zealand earthquake of 30th September, 2007

    NASA Astrophysics Data System (ADS)

    Ibanga, J. I.; Akpan, A. E.; George, N. J.; Ekanem, A. M.; George, A. M.

    2018-06-01

    Using the IAP experiment on board, the DEMETER and TEC from GPS data, unusual ionospheric variations have been observed some days before the 7.4 magnitude New Zealand earthquake. Both sets of data recorded perturbations 10 days before the earthquake at about the same time. The total ion density per centimeter cube (cm-3), recorded a variation of 6.94 while the differential total electron content (DTEC) in total electron content unit 1016 electron per metre square gave a value of 2.93TECU. The observed anomalies were screened for false alarm using the geomagnetic indices of Kernnifzer digit (Kp) and disturbance storm time (Dst.) It was however seen that the state of the ionosphere was geomagnetically quiet during this period; hence the observed variations were seismogenic.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Tremor, remote triggering and earthquake cycle

    NASA Astrophysics Data System (ADS)

    Peng, Z.

    2012-12-01

    Deep tectonic tremor and episodic slow-slip events have been observed at major plate-boundary faults around the Pacific Rim. These events have much longer source durations than regular earthquakes, and are generally located near or below the seismogenic zone where regular earthquakes occur. Tremor and slow-slip events appear to be extremely stress sensitive, and could be instantaneously triggered by distant earthquakes and solid earth tides. However, many important questions remain open. For example, it is still not clear what are the necessary conditions for tremor generation, and how remote triggering could affect large earthquake cycle. Here I report a global search of tremor triggered by recent large teleseismic earthquakes. We mainly focus on major subduction zones around the Pacific Rim. These include the southwest and northeast Japan subduction zones, the Hikurangi subduction zone in New Zealand, the Cascadia subduction zone, and the major subduction zones in Central and South America. In addition, we examine major strike-slip faults around the Caribbean plate, the Queen Charlotte fault in northern Pacific Northwest Coast, and the San Andreas fault system in California. In each place, we first identify triggered tremor as a high-frequency non-impulsive signal that is in phase with the large-amplitude teleseismic waves. We also calculate the dynamic stress and check the triggering relationship with the Love and Rayleigh waves. Finally, we calculate the triggering potential with the local fault orientation and surface-wave incident angles. Our results suggest that tremor exists at many plate-boundary faults in different tectonic environments, and could be triggered by dynamic stress as low as a few kPas. In addition, we summarize recent observations of slow-slip events and earthquake swarms triggered by large distant earthquakes. Finally, we propose several mechanisms that could explain apparent clustering of large earthquakes around the world.

  12. The Christchurch earthquake stroke incidence study.

    PubMed

    Wu, Teddy Y; Cheung, Jeanette; Cole, David; Fink, John N

    2014-03-01

    We examined the impact of major earthquakes on acute stroke admissions by a retrospective review of stroke admissions in the 6 weeks following the 4 September 2010 and 22 February 2011 earthquakes. The control period was the corresponding 6 weeks in the previous year. In the 6 weeks following the September 2010 earthquake there were 97 acute stroke admissions, with 79 (81.4%) ischaemic infarctions. This was similar to the 2009 control period which had 104 acute stroke admissions, of whom 80 (76.9%) had ischaemic infarction. In the 6 weeks following the February 2011 earthquake, there were 71 stroke admissions, and 61 (79.2%) were ischaemic infarction. This was less than the 96 strokes (72 [75%] ischaemic infarction) in the corresponding control period. None of the comparisons were statistically significant. There was also no difference in the rate of cardioembolic infarction from atrial fibrillation between the study periods. Patients admitted during the February 2011 earthquake period were less likely to be discharged directly home when compared to the control period (31.2% versus 46.9%, p=0.036). There was no observable trend in the number of weekly stroke admissions between the 2 weeks leading to and 6 weeks following the earthquakes. Our results suggest that severe psychological stress from earthquakes did not influence the subsequent short term risk of acute stroke, but the severity of the earthquake in February 2011 and associated civil structural damages may have influenced the pattern of discharge for stroke patients. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Precisely locating the Klamath Falls, Oregon, earthquakes

    USGS Publications Warehouse

    Qamar, A.; Meagher, K.L.

    1993-01-01

    In this article we present preliminary results of a close-in, instrumental study of the Klamath Falls earthquake sequence, carried as a cooperative effort by scientists from the U.S Geological Survey (USGS) and universities in Washington, Orgeon, and California. In addition to obtaining much mroe accurate earthquake locations, this study has improved our understanding of the relationship between seismicity and mapped faults in the region. 

  14. Mexican Earthquakes and Tsunamis Catalog Reviewed

    NASA Astrophysics Data System (ADS)

    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

  15. The persistence of directivity in small earthquakes

    USGS Publications Warehouse

    Boatwright, J.

    2007-01-01

    We derive a simple inversion of peak ground acceleration (PGA) or peak ground velocity (PGV) for rupture direction and rupture velocity and then test this inversion on the peak motions obtained from seven 3.5 ??? M ??? 4.1 earthquakes that occurred in two clusters in November 2002 and February 2003 near San Ramon, California. These clusters were located on two orthogonal strike-slip faults so that the events share the same approximate focal mechanism but not the same fault plane. Three earthquakes exhibit strong directivity, but the other four earthquakes exhibit relatively weak directivity. We use the residual PGAs and PGVs from the other six events to determine station corrections for each earthquake. The inferred rupture directions unambiguously identify the fault plane for the three earthquakes with strong directivity and for three of the four earthquakes with weak directivity. The events with strong directivity have fast rupture velocities (0.63????? v ??? 0.87??); the events with weak directivity either rupture more slowly (0.17????? v ???0.35??) or bilaterally. The simple unilateral inversion cannot distinguish between slow and bilateral ruptures: adding a bilateral rupture component degrades the fit of the rupture directions to the fault planes. By comparing PGAs from the events with strong and weak directivity, we show how an up-dip rupture in small events can distort the attenuation of peak ground motion with distance. When we compare the rupture directions of the earthquakes to the location of aftershocks in the two clusters, we find than almost all the aftershocks of the three earthquakes with strong directivity occur within 70?? of the direction of rupture.

  16. Brady's Geothermal Field Nodal Seismometer Earthquake Data

    SciTech Connect

    Kurt Feigl

    90-second records of data from 238 three-component nodal seismometer deployed at Bradys geothermal field. The time window catches an earthquake arrival. Earthquake data from USGS online catalog: Magnitude: 4.3 ml +/- 0.4 Location: 38.479 deg N 118.366 deg W +/- 0.7 km Depth: 9.9 km +/- 0.7 Date and Time: 2016-03-21 07:37:10.535 UTC

  17. Brady's Geothermal Field DAS Earthquake Data

    SciTech Connect

    Kurt Feigl

    The submitted data correspond to the vibration caused by a 3.4 M earthquake and captured by the DAS horizontal and vertical arrays during the PoroTomo Experiment. Earthquake information : M 4.3 - 23km ESE of Hawthorne, Nevada Time: 2016-03-21 07:37:10 (UTC) Location: 38.479 N 118.366 W Depth: 9.9 km

  18. Children and the San Fernando earthquake

    USGS Publications Warehouse

    Howard, S. J.

    1980-01-01

    Before dawn, on February 9, 1971, a magnitude 6.4 earthquake occurred in the San Fernando Valley of California. On the following day, theSan Fernando Valley Child Guidance Clinic, through radio and newspapers, offered mental health crises services to children frightened by the earthquake. Response to this invitation was immediate and almost overwhelming. During the first 2 weeks, the Clinic's staff counseled hundreds of children who were experiencing various degrees of anxiety. 

  19. Infrasound Signal Characteristics from Small Earthquakes

    DTIC Science & Technology

    2011-09-01

    INFRASOUND SIGNAL CHARACTERISTICS FROM SMALL EARTHQUAKES Stephen J. Arrowsmith1, J. Mark Hale2, Relu Burlacu2, Kristine L. Pankow2, Brian W. Stump3...ABSTRACT Physical insight into source properties that contribute to the generation of infrasound signals is critical to understanding the...m, with one element being co-located with a seismic station. One of the goals of this project is the recording of infrasound from earthquakes of

  20. Collaboratory for the Study of Earthquake Predictability

    NASA Astrophysics Data System (ADS)

    Schorlemmer, D.; Jordan, T. H.; Zechar, J. D.; Gerstenberger, M. C.; Wiemer, S.; Maechling, P. J.

    2006-12-01

    Earthquake prediction is one of the most difficult problems in physical science and, owing to its societal implications, one of the most controversial. The study of earthquake predictability has been impeded by the lack of an adequate experimental infrastructure---the capability to conduct scientific prediction experiments under rigorous, controlled conditions and evaluate them using accepted criteria specified in advance. To remedy this deficiency, the Southern California Earthquake Center (SCEC) is working with its international partners, which include the European Union (through the Swiss Seismological Service) and New Zealand (through GNS Science), to develop a virtual, distributed laboratory with a cyberinfrastructure adequate to support a global program of research on earthquake predictability. This Collaboratory for the Study of Earthquake Predictability (CSEP) will extend the testing activities of SCEC's Working Group on Regional Earthquake Likelihood Models, from which we will present first results. CSEP will support rigorous procedures for registering prediction experiments on regional and global scales, community-endorsed standards for assessing probability-based and alarm-based predictions, access to authorized data sets and monitoring products from designated natural laboratories, and software to allow researchers to participate in prediction experiments. CSEP will encourage research on earthquake predictability by supporting an environment for scientific prediction experiments that allows the predictive skill of proposed algorithms to be rigorously compared with standardized reference methods and data sets. It will thereby reduce the controversies surrounding earthquake prediction, and it will allow the results of prediction experiments to be communicated to the scientific community, governmental agencies, and the general public in an appropriate research context.