Science.gov

Sample records for aftershock mobilization program

  1. Kinect Technology Game Play to Mimic Quake Catcher Network (QCN) Sensor Deployment During a Rapid Aftershock Mobilization Program (RAMP)

    NASA Astrophysics Data System (ADS)

    Kilb, D. L.; Yang, A.; Rohrlick, D.; Cochran, E. S.; Lawrence, J.; Chung, A. I.; Neighbors, C.; Choo, Y.

    2011-12-01

    The Kinect technology allows for hands-free game play, greatly increasing the accessibility of gaming for those uncomfortable using controllers. How it works is the Kinect camera transmits invisible near-infrared light and measures its "time of flight" to reflect off an object, allowing it to distinguish objects within 1 centimeter in depth and 3 mm in height and width. The middleware can also respond to body gestures and voice commands. Here, we use the Kinect Windows SDK software to create a game that mimics how scientists deploy seismic instruments following a large earthquake. The educational goal of the game is to allow the players to explore 3D space as they learn about the Quake Catcher Network's (QCN) Rapid Aftershock Mobilization Program (RAMP). Many of the scenarios within the game are taken from factual RAMP experiences. To date, only the PC platform (or a Mac running PC emulator software) is available for use, but we hope to move to other platforms (e.g., Xbox 360, iPad, iPhone) as they become available. The game is written in programming language C# using Microsoft XNA and Visual Studio 2010, graphic shading is added using High Level Shader Language (HLSL), and rendering is produced using XNA's graphics libraries. Key elements of the game include selecting sensor locations, adequately installing the sensor, and monitoring the incoming data. During game play aftershocks can occur unexpectedly, as can other problems that require attention (e.g., power outages, equipment failure, and theft). The player accrues points for quickly deploying the first sensor (recording as many initial aftershocks as possible), correctly installing the sensors (orientation with respect to north, properly securing, and testing), distributing the sensors adequately in the region, and troubleshooting problems. One can also net points for efficient use of game play time. Setting up for game play in your local environment requires: (1) the Kinect hardware ( $145); (2) a computer

  2. NASA's mobile satellite development program

    NASA Technical Reports Server (NTRS)

    Rafferty, William; Dessouky, Khaled; Sue, Miles

    1988-01-01

    A Mobile Satellite System (MSS) will provide data and voice communications over a vast geographical area to a large population of mobile users. A technical overview is given of the extensive research and development studies and development performed under NASA's mobile satellite program (MSAT-X) in support of the introduction of a U.S. MSS. The critical technologies necessary to enable such a system are emphasized: vehicle antennas, modulation and coding, speech coders, networking and propagation characterization. Also proposed is a first, and future generation MSS architecture based upon realized ground segment equipment and advanced space segment studies.

  3. The GalileoMobile Program

    NASA Astrophysics Data System (ADS)

    Spinelli, P. F.

    2014-10-01

    GalileoMobile is an itinerant science education program that is bringing astronomy closer to young people around the world since 2009 (http://galileo-mobile.org/). GalileoMobile acts in areas where outreach projects are scarce or non-existent. It is a purely non-profit initiative run by 22 volunteers (astronomers, educators and science communicators) from all over the world. The team seeks to promote cultural interaction among people beyond geographical borders and spread the message that we all live under the same sky.

  4. The Education Mobility Assistance Program.

    ERIC Educational Resources Information Center

    Ohio State Legislative Office of Education Oversight, Columbus.

    The Education Mobility Assistance Program (EMAP) was created in Ohio in 1979 to provide funds to school districts that volunteered to racially desegregate their schools by transferring students. This report evaluates the impact of EMAP funds in reducing the number of racially isolated schools and in providing equal educational opportunities for…

  5. Mechanical origin of aftershocks.

    PubMed

    Lippiello, E; Giacco, F; Marzocchi, W; Godano, C; de Arcangelis, L

    2015-01-01

    Aftershocks are the most striking evidence of earthquake interactions and the physical mechanisms at the origin of their occurrence are still intensively debated. Novel insights stem from recent results on the influence of the faulting style on the aftershock organisation in magnitude and time. Our study shows that the size of the aftershock zone depends on the fault geometry. We find that positive correlations among parameters controlling aftershock occurrence in time, energy and space are a stable feature of seismicity independently of magnitude range and geographic areas. We explain the ensemble of experimental findings by means of a description of the Earth Crust as an heterogeneous elastic medium coupled with a Maxwell viscoelastic asthenosphere. Our results show that heterogeneous stress distribution in an elastic layer combined with a coupling to a viscous flow are sufficient ingredients to describe the physics of aftershock triggering. PMID:26497720

  6. Mechanical origin of aftershocks.

    PubMed

    Lippiello, E; Giacco, F; Marzocchi, W; Godano, C; de Arcangelis, L

    2015-10-26

    Aftershocks are the most striking evidence of earthquake interactions and the physical mechanisms at the origin of their occurrence are still intensively debated. Novel insights stem from recent results on the influence of the faulting style on the aftershock organisation in magnitude and time. Our study shows that the size of the aftershock zone depends on the fault geometry. We find that positive correlations among parameters controlling aftershock occurrence in time, energy and space are a stable feature of seismicity independently of magnitude range and geographic areas. We explain the ensemble of experimental findings by means of a description of the Earth Crust as an heterogeneous elastic medium coupled with a Maxwell viscoelastic asthenosphere. Our results show that heterogeneous stress distribution in an elastic layer combined with a coupling to a viscous flow are sufficient ingredients to describe the physics of aftershock triggering.

  7. Mechanical origin of aftershocks

    PubMed Central

    Lippiello, E.; Giacco, F.; Marzocchi, W.; Godano, C.; de Arcangelis, L.

    2015-01-01

    Aftershocks are the most striking evidence of earthquake interactions and the physical mechanisms at the origin of their occurrence are still intensively debated. Novel insights stem from recent results on the influence of the faulting style on the aftershock organisation in magnitude and time. Our study shows that the size of the aftershock zone depends on the fault geometry. We find that positive correlations among parameters controlling aftershock occurrence in time, energy and space are a stable feature of seismicity independently of magnitude range and geographic areas. We explain the ensemble of experimental findings by means of a description of the Earth Crust as an heterogeneous elastic medium coupled with a Maxwell viscoelastic asthenosphere. Our results show that heterogeneous stress distribution in an elastic layer combined with a coupling to a viscous flow are sufficient ingredients to describe the physics of aftershock triggering. PMID:26497720

  8. TACOM-USU intelligent mobility program

    NASA Astrophysics Data System (ADS)

    Moore, Kevin L.; Gerhart, Grant R.

    2004-09-01

    Over a six year period the US Army Tank-Automotive and Armaments Command's Intelligent Mobility Program sponsored research to develop and demonstrate enhanced mobility concepts for unmanned ground vehicles. In this paper we describe the Intelligent Mobility Program"s research accomplishments achieved at Utah State University"s (USU) Center for Self-Organizing and Intelligent Systems (CSIOS). The CSOIS program was based on USU"s "smart wheel" technology, which enables design of an omni-directional vehicle (ODV). Through the course of the program, USU researchers built thirty robots using eight distinct ODV robot designs. These robots were also demonstrated in a number of application scenarios. The program has culminated in the actual fielding of the final robot developed, the ODIS-T2, which was designed for undervehicle inspection at security checkpoints. The design and deployment of these robots required research advances in mechanical and vetronics design, sensor integration, control engineering and intelligent behavior generation algorithms, system integration, and human interface. An overview of the USU-developed robotics technology is presented that details the technology development and technical accomplishments achieved by the TACOM-USU Intelligent Mobility Program, with a focus on the actual hardware produced.

  9. Gender Gap in the ERASMUS Mobility Program.

    PubMed

    Böttcher, Lucas; Araújo, Nuno A M; Nagler, Jan; Mendes, José F F; Helbing, Dirk; Herrmann, Hans J

    2016-01-01

    Studying abroad has become very popular among students. The ERASMUS mobility program is one of the largest international student exchange programs in the world, which has supported already more than three million participants since 1987. We analyzed the mobility pattern within this program in 2011-12 and found a gender gap across countries and subject areas. Namely, for almost all participating countries, female students are over-represented in the ERASMUS program when compared to the entire population of tertiary students. The same tendency is observed across different subject areas. We also found a gender asymmetry in the geographical distribution of hosting institutions, with a bias of male students in Scandinavian countries. However, a detailed analysis reveals that this latter asymmetry is rather driven by subject and consistent with the distribution of gender ratios among subject areas. PMID:26901133

  10. Gender Gap in the ERASMUS Mobility Program

    PubMed Central

    Böttcher, Lucas; Araújo, Nuno A. M.; Nagler, Jan; Mendes, José F. F.; Helbing, Dirk; Herrmann, Hans J.

    2016-01-01

    Studying abroad has become very popular among students. The ERASMUS mobility program is one of the largest international student exchange programs in the world, which has supported already more than three million participants since 1987. We analyzed the mobility pattern within this program in 2011-12 and found a gender gap across countries and subject areas. Namely, for almost all participating countries, female students are over-represented in the ERASMUS program when compared to the entire population of tertiary students. The same tendency is observed across different subject areas. We also found a gender asymmetry in the geographical distribution of hosting institutions, with a bias of male students in Scandinavian countries. However, a detailed analysis reveals that this latter asymmetry is rather driven by subject and consistent with the distribution of gender ratios among subject areas. PMID:26901133

  11. Gender Gap in the ERASMUS Mobility Program.

    PubMed

    Böttcher, Lucas; Araújo, Nuno A M; Nagler, Jan; Mendes, José F F; Helbing, Dirk; Herrmann, Hans J

    2016-01-01

    Studying abroad has become very popular among students. The ERASMUS mobility program is one of the largest international student exchange programs in the world, which has supported already more than three million participants since 1987. We analyzed the mobility pattern within this program in 2011-12 and found a gender gap across countries and subject areas. Namely, for almost all participating countries, female students are over-represented in the ERASMUS program when compared to the entire population of tertiary students. The same tendency is observed across different subject areas. We also found a gender asymmetry in the geographical distribution of hosting institutions, with a bias of male students in Scandinavian countries. However, a detailed analysis reveals that this latter asymmetry is rather driven by subject and consistent with the distribution of gender ratios among subject areas.

  12. Neurolinguistic Programming in Orientation and Mobility.

    ERIC Educational Resources Information Center

    Williams, M. F.; Jacobson, W. H.

    1989-01-01

    The article describes the neurolinguistic programing model and applies it to teaching orientation and mobility skills to congenitally blind students, who have access to only the auditory and kinesthetic primary systems. Understanding the effects on thought of limited representational systems can help trainers teach more effective cane or dog guide…

  13. Scaffolding Java Programming on a Mobile Phone for Novice Learners

    ERIC Educational Resources Information Center

    Mbogo, Chao; Blake, Edwin; Suleman, Hussein

    2015-01-01

    The ubiquity of mobile phones provides an opportunity to use them as a resource for construction of programs beyond the classroom. However, limitations of mobile phones impede their use as typical programming environments. This research proposes that programming environments on mobile phones should include scaffolding techniques specifically…

  14. Dartmouth College Earth Sciences Mobile Field Program

    NASA Astrophysics Data System (ADS)

    Meyer, E. E.; Osterberg, E. C.; Dade, W. B.; Sonder, L. J.; Renshaw, C. E.; Kelly, M. A.; Hawley, R. L.; Chipman, J. W.; Mikucki, J.; Posmentier, E. S.; Moore, J. R.

    2011-12-01

    For the last 50 years the Department of Earth Sciences at Dartmouth College has offered a term-long, undergraduate field program, informally called "the Stretch". A student typically enrolls during fall quarter of his or her junior year soon after choosing a major or minor. The program thus provides valuable field context for courses that a student will take during the remainder of his or her undergraduate career. Unlike many traditional field camps that focus on one particular region, the Stretch is a mobile program that currently travels through Western North America, from the Canadian Rockies to the Grand Canyon. The program spans two and a half months, during which time undergraduates, graduate TAs, and faculty live, work, and learn collaboratively. Dartmouth College faculty members sequentially teach individual 1- to 2-week segments that focus on their interests and expertise; currently, there are a total of eight segments led by eleven faculty members. Consequently, topics are diverse and include economic geology, geobiology, geomorphology, glaciology, glacial geology, geophysics, hydrogeology, paleontology, stratigraphy, structure and tectonics, and volcanology. The field localities are equally varied, including the alpine glaciers of western Alberta, the national parks of Montana, Wyoming and Utah, the eastern Sierra Nevada, the southern Great Basin, and highlight such classic geological field locales as Sheep Mountain in Wyoming's Bighorn Basin, Death Valley, and the Grand Canyon. Overall, the program aims to: 1) give students a broad perspective on the timing and nature of the processes that resulted in the landscape and underlying geology of western North America; and 2) introduce students to a wide variety of geological environments, field techniques, and research equipment. Students emerge from the program with wide-ranging exposure to active research questions as well as a working knowledge of core field skills in the earth sciences. Stretch students

  15. The global aftershock zone

    USGS Publications Warehouse

    Parsons, Thomas E.; Margaret Segou,; Warner Marzocchi,

    2014-01-01

    The aftershock zone of each large (M ≥ 7) earthquake extends throughout the shallows of planet Earth. Most aftershocks cluster near the mainshock rupture, but earthquakes send out shivers in the form of seismic waves, and these temporary distortions are large enough to trigger other earthquakes at global range. The aftershocks that happen at great distance from their mainshock are often superposed onto already seismically active regions, making them difficult to detect and understand. From a hazard perspective we are concerned that this dynamic process might encourage other high magnitude earthquakes, and wonder if a global alarm state is warranted after every large mainshock. From an earthquake process perspective we are curious about the physics of earthquake triggering across the magnitude spectrum. In this review we build upon past studies that examined the combined global response to mainshocks. Such compilations demonstrate significant rate increases during, and immediately after (~ 45 min) M > 7.0 mainshocks in all tectonic settings and ranges. However, it is difficult to find strong evidence for M > 5 rate increases during the passage of surface waves in combined global catalogs. On the other hand, recently published studies of individual large mainshocks associate M > 5 triggering at global range that is delayed by hours to days after surface wave arrivals. The longer the delay between mainshock and global aftershock, the more difficult it is to establish causation. To address these questions, we review the response to 260 M ≥ 7.0 shallow (Z ≤ 50 km) mainshocks in 21 global regions with local seismograph networks. In this way we can examine the detailed temporal and spatial response, or lack thereof, during passing seismic waves, and over the 24 h period after their passing. We see an array of responses that can involve immediate and widespread seismicity outbreaks, delayed and localized earthquake clusters, to no response at all. About 50% of the

  16. Postseismic relaxation and aftershocks

    USGS Publications Warehouse

    Savage, J.C.; Svarc, J.L.; Yu, S.-B.

    2007-01-01

    Perfettini et al. (2005) suggested that the temporal dependence of surface displacements u(t) measured in the epicentral area following an earthquake is related to N(t), the cumulative number of aftershocks, by the equation u(t) = a + bt + cN(t) + d(1 - e-??t), where a, b, c, d, and ?? are constants chosen to fit the data and t is the postearthquake time. N(t) appears in the expression for u(t) because both the aftershocks and a portion of u(t) are thought to be driven by the same source, postseismic fault creep at subseismogenic depths on the downdip extension of the coseismic rupture. We show that this equation with the actually observed N(t) fits the postseismic displacements recorded on several baselines following each of five earthquakes: 1999 M7.6 Chi-Chi (Taiwan), 1999 M7.1 Hector Mine (southern California), 2002 M7.9 Denali (central Alaska), 2003 M6.5 San Simeon (central California), and 2004 M6.0 Parkfield (central California) earthquakes. Although there are plausible physical interpretations for each of the terms in the expression for u(t), the large number of adjustable constants (a, b, c, d, and ??) involved in fitting the rather simple postseismic displacements diminishes the significance of the fit. Because the observed N(t) is well fit by the modified Omori's law, fault creep at depth presumably exhibits the same temporal dependence. That dependence could be explained if the rheology of the fault downdip from the coseismic rupture is consistent with ordinary transient creep. Montesi (2004) demonstrated that power law creep across a shear zone at depth would also produce that temporal signal.

  17. Virtual Mobility in Higher Education. The UNED Campus Net Program

    ERIC Educational Resources Information Center

    Aguado, Teresa; Monge, Fernando; Del Olmo, Alicia

    2014-01-01

    We present the UNED Virtual Mobility Campus Net Program, implemented since 2012 in collaboration with European and Latin American universities. Program's objectives, participating institutions, procedures, and evaluation are exposed. Virtual mobility is understood as a meaningful strategy for intercultural learning by studying an undergraduate or…

  18. Intelligent mobility through omnidirectional vehicles: a research program

    NASA Astrophysics Data System (ADS)

    Flann, Nicholas S.; Gunderson, Robert W.; Moore, Kevin L.; Wood, Carl G.

    2000-07-01

    Beginning in FY98 and continuing in FY99, the Center for Self-Organizing and Intelligent Systems (CSOIS) at Utah State University (USU) has been funded by the US Army Tank-Automotive and Armaments Command's (TACOM) Intelligent Mobility Program to develop and demonstrate enhanced mobility concepts for unmanned ground vehicles (UGV). The long-range goal of the program is to develop and demonstrate enabling technologies that allow lightweight robotic and semiautonomous ground vehicles to achieve on-road and off-road mobility and survivability similar to current manned, wheeled, and tracked military vehicles, with a focus on small-scale to mid-scale vehicles. This paper describes the design concept and the performance of the T-series of robotic vehicles resulting from the TACOM Intelligent Mobility funding at USU (the T1, T2 and T3). USU-TACOM intelligent mobility concepts discussed in the paper include: (1) inherent mobility capability improvements, achieve through the unique concept of USU's omni-directional vehicle (ODV) steering design, which features six independently-controlled smart wheels; (2) intelligent mobility control, enhanced through intelligent coordination and control of each of the six wheels in the ODV vehicles; (3) global mobility control, enhanced through USU optimal multi-agent mission and mobility planning system; and (4) future mobility capability and control.

  19. Mobilize Your instruction Program with Wireless Technology.

    ERIC Educational Resources Information Center

    Mathias, Molly Susan; Heser, Steven

    2002-01-01

    Describes the use of wireless technology for library bibliographic instruction at the Milwaukee Area Technical College. Highlights include a wireless mobile cart that holds laptop computers; faculty support; future plans; and recommendations, including investigating technology infrastructure and marketing. (LRW)

  20. Barriers to International Student Mobility: Evidence from the Erasmus Program

    ERIC Educational Resources Information Center

    Souto-Otero, Manuel; Huisman, Jeroen; Beerkens, Maarja; de Wit, Hans; Vujic, Suncica

    2013-01-01

    In this article, we look at the barriers to international student mobility, with particular reference to the European Erasmus program. Much is known about factors that support or limit student mobility, but very few studies have made comparisons between participants and nonparticipants. Making use of a large data set on Erasmus and non-Erasmus…

  1. Creating a Successful School-Based Mobile Dental Program

    ERIC Educational Resources Information Center

    Jackson, David M.; Jahnke, Lauren R.; Kerber, Lisa; Nyer, Genie; Siemens, Kammi; Clark, Carol

    2007-01-01

    Background: Dental disease is one of the leading causes of school absenteeism for children. This article describes the creation and evolution of the St. David's Dental Program, a mobile school-based dental program for children. Methods: The dental program is a collaboration of community partners in Central Texas that provides free dental care to…

  2. Forecasting magnitude, time, and location of aftershocks for aftershock hazard

    NASA Astrophysics Data System (ADS)

    Chen, K.; Tsai, Y.; Huang, M.; Chang, W.

    2011-12-01

    In this study we investigate the spatial and temporal seismicity parameters of the aftershock sequence accompanying the 17:47 20 September 1999 (UTC) 7.45 Chi-Chi earthquake Taiwan. Dividing the epicentral zone into north of the epicenter, at the epicenter, and south of the epicenter, it is found that immediately after the earthquake the area close by the epicenter had a lower value than both the northern and southern sections. This pattern suggests that at the time of the Chi-Chi earthquake, the area close by the epicenter remained prone to large magnitude aftershocks and strong shaking. However, with time the value increases. An increasing value indicates a reduced likelihood of large magnitude aftershocks. The study also shows that the value is higher at the southern section of the epicentral zone, indicating a faster rate of decay in this section. The primary purpose of this paper is to design a predictive model for forecasting the magnitude, time, and location of aftershocks to large earthquakes. The developed model is presented and applied to the 17:47 20 September 1999 7.45 Chi-Chi earthquake Taiwan, and the 09:32 5 November 2009 (UTC) Nantou 6.19, and 00:18 4 March 2010 (UTC) Jiashian 6.49 earthquake sequences. In addition, peak ground acceleration trends for the Nantou and Jiashian aftershock sequences are predicted and compared to actual trends. The results of the estimated peak ground acceleration are remarkably similar to calculations from recorded magnitudes in both trend and level. To improve the predictive skill of the model for occurrence time, we use an empirical relation to forecast the time of aftershocks. The empirical relation improves time prediction over that of random processes. The results will be of interest to seismic mitigation specialists and rescue crews. We apply also the parameters and empirical relation from Chi-Chi aftershocks of Taiwan to forecast aftershocks with magnitude M > 6.0 of 05:46 11 March 2011 (UTC) Tohoku 9

  3. Accommodating Mobile Learning in College Programs

    ERIC Educational Resources Information Center

    Alden, Jay

    2013-01-01

    Mobile devices and applications are expected to have a significant impact on teaching and learning in the near future. Yet colleges and universities are currently facing severe budget constraints and discretionary funding is restricted for new initiatives. The question addressed in this paper is: "What strategy should an institution of higher…

  4. Essential factors for a healthy RN educational mobility program.

    PubMed

    Messmer, P R; Miller, E; Spruck, M

    1994-01-01

    There is little research concerning which factors registered nurse (RN) students perceive as constituting a healthy educational mobility program. Because of this, a study was undertaken to identify the factors that RN students perceive as contributing to a healthy educational mobility RN/BSN/MSN program. Findings indicated that the RN students value flexibility, ease in planning, and convenience of course offerings as most important to their program selection. Registered nurse students emphasized the critical factors of faculty sensitivity to students' diverse opinions, faculty respect for students, and faculty expertise as important. These findings highlight the importance of sensitizing faculty members and nurse administrators to the needs of RN students. PMID:7854637

  5. Larger aftershocks happen farther away: nonseparability of magnitude and spatial distributions of aftershocks

    USGS Publications Warehouse

    Van Der Elst, Nicholas; Shaw, Bruce E.

    2015-01-01

    Aftershocks may be driven by stress concentrations left by the main shock rupture or by elastic stress transfer to adjacent fault sections or strands. Aftershocks that occur within the initial rupture may be limited in size, because the scale of the stress concentrations should be smaller than the primary rupture itself. On the other hand, aftershocks that occur on adjacent fault segments outside the primary rupture may have no such size limitation. Here we use high-precision double-difference relocated earthquake catalogs to demonstrate that larger aftershocks occur farther away than smaller aftershocks, when measured from the centroid of early aftershock activity—a proxy for the initial rupture. Aftershocks as large as or larger than the initiating event nucleate almost exclusively in the outer regions of the aftershock zone. This observation is interpreted as a signature of elastic rebound in the earthquake catalog and can be used to improve forecasting of large aftershocks.

  6. 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

  7. International Aftershock Forecasting: Lessons from the Gorkha Earthquake

    NASA Astrophysics Data System (ADS)

    Michael, A. J.; Blanpied, M. L.; Brady, S. R.; van der Elst, N.; Hardebeck, J.; Mayberry, G. C.; Page, M. T.; Smoczyk, G. M.; Wein, A. M.

    2015-12-01

    Following the M7.8 Gorhka, Nepal, earthquake of April 25, 2015 the USGS issued a series of aftershock forecasts. The initial impetus for these forecasts was a request from the USAID Office of US Foreign Disaster Assistance to support their Disaster Assistance Response Team (DART) which coordinated US Government disaster response, including search and rescue, with the Government of Nepal. Because of the possible utility of the forecasts to people in the region and other response teams, the USGS released these forecasts publicly through the USGS Earthquake Program web site. The initial forecast used the Reasenberg and Jones (Science, 1989) model with generic parameters developed for active deep continental regions based on the Garcia et al. (BSSA, 2012) tectonic regionalization. These were then updated to reflect a lower productivity and higher decay rate based on the observed aftershocks, although relying on teleseismic observations, with a high magnitude-of-completeness, limited the amount of data. After the 12 May M7.3 aftershock, the forecasts used an Epidemic Type Aftershock Sequence model to better characterize the multiple sources of earthquake clustering. This model provided better estimates of aftershock uncertainty. These forecast messages were crafted based on lessons learned from the Christchurch earthquake along with input from the U.S. Embassy staff in Kathmandu. Challenges included how to balance simple messaging with forecasts over a variety of time periods (week, month, and year), whether to characterize probabilities with words such as those suggested by the IPCC (IPCC, 2010), how to word the messages in a way that would translate accurately into Nepali and not alarm the public, and how to present the probabilities of unlikely but possible large and potentially damaging aftershocks, such as the M7.3 event, which had an estimated probability of only 1-in-200 for the week in which it occurred.

  8. Learning Programming with IPRO: The Effects of a Mobile, Social Programming Environment

    ERIC Educational Resources Information Center

    Martin, Taylor; Berland, Matthew; Benton, Tom; Smith, Carmen Petrick

    2013-01-01

    In this paper, we present two studies examining how high school students learn to program in a mobile, social programming environment that we have developed and deployed ("IPRO"). IPRO is delivered, with an associated curriculum, as an iPod Touch app and is freely and publicly available. We find that the affordances of mobility and…

  9. Performance of aftershock forecasts: problem and formulation

    NASA Astrophysics Data System (ADS)

    Jiang, C.; Wu, Z.; Li, L.

    2010-12-01

    WFSD project deals with the problems of earthquake physics, in which one of the important designed aims is the forecast of the on-going aftershock activity of the Wenchuan earthquake, taking the advantage of the fast response to great earthquakes. Correlation between fluid measurements and aftershocks provided heuristic clues to the forecast of aftershocks, invoking the discussion on the performance of such ‘precursory anomalies’, even if in a retrospective perspective. In statistical seismology, one of the critical issues is how to test the statistical significance of an earthquake forecast scheme against real seismic activity. Due to the special characteristics of aftershock series and the feature of aftershock forecasts that it deals with a limited spatial range and specific temporal duration, the test of the performance of aftershock forecasts has to be different from the standard tests for main shock series. In this presentation we address and discuss the possible schemes for testing the performance of aftershock forecasts - a seemingly simple but practically important issue in statistical seismology. As a simple and preliminary approach, we use an alternative form of Receiver Operating Characteristic (ROC) test, as well as other similar tests, considering the properties of aftershock series by using Omori law, ETAS model, and/or CFS calculation. We also discussed the lessons and experiences of the Wenchuan aftershock forecasts, exploring how to make full use of the present knowledge of the regularity of aftershocks to serve the earthquake rescue and relief endeavor as well as the post-earthquake reconstruction.

  10. NASA's mobile satellite communications program; ground and space segment technologies

    NASA Technical Reports Server (NTRS)

    Naderi, F.; Weber, W. J.; Knouse, G. H.

    1984-01-01

    This paper describes the Mobile Satellite Communications Program of the United States National Aeronautics and Space Administration (NASA). The program's objectives are to facilitate the deployment of the first generation commercial mobile satellite by the private sector, and to technologically enable future generations by developing advanced and high risk ground and space segment technologies. These technologies are aimed at mitigating severe shortages of spectrum, orbital slot, and spacecraft EIRP which are expected to plague the high capacity mobile satellite systems of the future. After a brief introduction of the concept of mobile satellite systems and their expected evolution, this paper outlines the critical ground and space segment technologies. Next, the Mobile Satellite Experiment (MSAT-X) is described. MSAT-X is the framework through which NASA will develop advanced ground segment technologies. An approach is outlined for the development of conformal vehicle antennas, spectrum and power-efficient speech codecs, and modulation techniques for use in the non-linear faded channels and efficient multiple access schemes. Finally, the paper concludes with a description of the current and planned NASA activities aimed at developing complex large multibeam spacecraft antennas needed for future generation mobile satellite systems.

  11. Self-similar aftershock rates

    NASA Astrophysics Data System (ADS)

    Davidsen, Jörn; Baiesi, Marco

    2016-08-01

    In many important systems exhibiting crackling noise—an intermittent avalanchelike relaxation response with power-law and, thus, self-similar distributed event sizes—the "laws" for the rate of activity after large events are not consistent with the overall self-similar behavior expected on theoretical grounds. This is particularly true for the case of seismicity, and a satisfying solution to this paradox has remained outstanding. Here, we propose a generalized description of the aftershock rates which is both self-similar and consistent with all other known self-similar features. Comparing our theoretical predictions with high-resolution earthquake data from Southern California we find excellent agreement, providing particularly clear evidence for a unified description of aftershocks and foreshocks. This may offer an improved framework for time-dependent seismic hazard assessment and earthquake forecasting.

  12. Self-similar aftershock rates.

    PubMed

    Davidsen, Jörn; Baiesi, Marco

    2016-08-01

    In many important systems exhibiting crackling noise-an intermittent avalanchelike relaxation response with power-law and, thus, self-similar distributed event sizes-the "laws" for the rate of activity after large events are not consistent with the overall self-similar behavior expected on theoretical grounds. This is particularly true for the case of seismicity, and a satisfying solution to this paradox has remained outstanding. Here, we propose a generalized description of the aftershock rates which is both self-similar and consistent with all other known self-similar features. Comparing our theoretical predictions with high-resolution earthquake data from Southern California we find excellent agreement, providing particularly clear evidence for a unified description of aftershocks and foreshocks. This may offer an improved framework for time-dependent seismic hazard assessment and earthquake forecasting. PMID:27627324

  13. Self-similar aftershock rates.

    PubMed

    Davidsen, Jörn; Baiesi, Marco

    2016-08-01

    In many important systems exhibiting crackling noise-an intermittent avalanchelike relaxation response with power-law and, thus, self-similar distributed event sizes-the "laws" for the rate of activity after large events are not consistent with the overall self-similar behavior expected on theoretical grounds. This is particularly true for the case of seismicity, and a satisfying solution to this paradox has remained outstanding. Here, we propose a generalized description of the aftershock rates which is both self-similar and consistent with all other known self-similar features. Comparing our theoretical predictions with high-resolution earthquake data from Southern California we find excellent agreement, providing particularly clear evidence for a unified description of aftershocks and foreshocks. This may offer an improved framework for time-dependent seismic hazard assessment and earthquake forecasting.

  14. EXPERIMENTAL PROGRAM FOR MOBILIZING COLLEGE STUDENT VOLUNTEER SERVICES TO COMMUNITIES.

    ERIC Educational Resources Information Center

    ESSER, GEORGE H., JR.

    AN EXPERIMENT WAS CONDUCTED IN MOBILIZING COLLEGE STUDENTS FOR SUMMER ASSISTANCE IN COMMUNITY DEVELOPMENT AND POVERTY PROGRAMS. APPROXIMATELY 100 STUDENT VOLUNTEERS WERE CHOSEN TO PARTICIPATE ON THE BASES OF THEIR STABILITY, MATURITY, ABILITY TO COMMUNICATE, AND DEDICATION. THEY WERE PLACED IN SIX AREAS WHERE COMPREHENSIVE COMMUNITY ACTION…

  15. Monitoring 2015 Nepal aftershocks with the deployment of a TEXAN array in southern Tibet, China

    NASA Astrophysics Data System (ADS)

    Zhou, H. W.; Zou, Z.; Tong, S.; Zhang, J.; Liu, H.

    2015-12-01

    The Mw7.8 Nepal earthquake occurred on 4/25/2015 caused a continuous string of aftershocks, including the Mw7.3 main aftershock on 5/12/2015. The aftershocks, distributed mostly between the main shock and the main aftershock, are indicative of the structure of the main frontal thrust and associated fault system. Shortly after the Mw7.3 main aftershock, we conducted a field deployment of a 100-km-long array of 31 TEXAN miniature seismometers in southern Tibet, north of the Nepal-China boarder, from 5/20/2015 to 6/17/2015. This roughly north-south array with around 3 km in station spacing have recorded many aftershocks of the 2015 Nepal Earthquake series, including 22 aftershocks greater than M4.0, as well as over one hundred teleseismic events greater than M5.0, including the M7.8 deep earthquake in Chichi-shima, Japan and a sequence of M6.0 earthquakes in Solomon Islands. The purposes of deploying this mobile 2D array are: (1) Assessing the feasibility of deploying TEXAN seismometers in southern Tibet and the data quality; (2) Monitoring further aftershocks of the Nepal earthquake series and other events; and (3) Mapping the crustal structure beneath the array using regional and teleseismic data. It is encouraging that our first deployment has resulted in good data quality, and we are making a seismic profile beneath the 2D transect. Since the feasibility of deploying TEXAN's in southern Tibet is proven, we plan to make further deployment of TEXAN arrays to study crustal structure in southern Tibet.

  16. High-Resolution Low Power, Intergrated Aftershock and Microzonation System

    NASA Astrophysics Data System (ADS)

    Zimakov, L.; Passmore, P.

    2012-04-01

    Refraction Technology, Inc. has developed a self-contained, fully integrated Aftershock System, model 160-03, providing the customer simple and quick deployment during aftershock emergency mobilization and microzonation studies. The 160-03 has no external cables or peripheral equipment for command/control and operation in the field. The 160-03 contains three major components integrated in one case: a) 24-bit resolution state-of-the art low power ADC with CPU and Lid interconnect boards; b) power source; and c) three component 2 Hz sensors (two horizontals and one vertical), and built-in ±4g accelerometer. Optionally, the 1 Hz sensors can be built-in the 160-03 system at the customer's request. The self-contained rechargeable battery pack provides power autonomy up to 7 days during data acquisition at 200 sps on continuous three weak motion and triggered three strong motion recording channels. For longer power autonomy, the 160-03 Aftershock System battery pack can be charged from an external source (solar power system). The data in the field is recorded to a built-in swappable USB flash drive. The 160-03 configuration is fixed based on a configuration file stored on the system. The detailed specifications and performance are presented and discussed

  17. Modeling aftershocks as a stretched exponential relaxation

    NASA Astrophysics Data System (ADS)

    Mignan, A.

    2015-11-01

    The decay rate of aftershocks has been modeled as a power law since the pioneering work of Omori in the late nineteenth century. Although other expressions have been proposed in recent decades to describe the temporal behavior of aftershocks, the number of model comparisons remains limited. After reviewing the aftershock models published from the late nineteenth century until today, I solely compare the power law, pure exponential and stretched exponential expressions defined in their simplest forms. By applying statistical methods recommended recently in applied mathematics, I show that all aftershock sequences tested in three regional earthquake catalogs (Southern and Northern California, Taiwan) and with three declustering techniques (nearest-neighbor, second-order moment, window methods) follow a stretched exponential instead of a power law. These results infer that aftershocks are due to a simple relaxation process, in accordance with most other relaxation processes observed in Nature.

  18. Aftershock triggering by complete Coulomb stress changes

    USGS Publications Warehouse

    Kilb, Debi; Gomberg, J.; Bodin, P.

    2002-01-01

    We examine the correlation between seismicity rate change following the 1992, M7.3, Landers, California, earthquake and characteristics of the complete Coulomb failure stress (CFS) changes (??CFS(t)) that this earthquake generated. At close distances the time-varying "dynamic" portion of the stress change depends on how the rupture develops temporally and spatially and arises from radiated seismic waves and from permanent coseismic fault displacement. The permanent "static" portion (??CFS) depends only on the final coseismic displacement. ??CFS diminishes much more rapidly with distance than the transient, dynamic stress changes. A common interpretation of the strong correlation between ??CFS and aftershocks is that load changes can advance or delay failure. Stress changes may also promote failure by physically altering properties of the fault or its environs. Because it is transient, ??CFS(t) can alter the failure rate only by the latter means. We calculate both ??CFS and the maximum positive value of ??CFS(t) (peak ??CFS(t)) using a reflectivity program. Input parameters are constrained by modeling Landers displacement seismograms. We quantify the correlation between maps of seismicity rate changes and maps of modeled ??CFS and peak ??CFS(t) and find agreement for both models. However, rupture directivity, which does not affect ??CFS, creates larger peak ??CFS(t) values northwest of the main shock. This asymmetry is also observed in seismicity rate changes but not in ??CFS. This result implies that dynamic stress changes are as effective as static stress changes in triggering aftershocks and may trigger earthquakes long after the waves have passed.

  19. Aftershock Statistics explained from Geometric Reductionism

    NASA Astrophysics Data System (ADS)

    Mignan, Arnaud

    2016-04-01

    The decay of aftershocks has recently been shown to follow a stretched exponential function instead of the Omori law (Mignan, Geophys. Res. Lett., 2015). This triggers a complete re-investigation of aftershock statistics in Southern California and a new physical interpretation of these results: (1) After verifying the stretched exponential behavior of aftershocks in time, I show that aftershocks follow a pure exponential in space. I then (re)demonstrate that K(M) = exp(α(M-mmin-ΔmB)) with K the aftershock production by mainshock magnitude M, α the Gutenberg-Richter distribution slope and ΔmB Båth's parameter. Based on these observations, I propose the Recursive Aftershock Stretched Exponential (RASE) model. (2) I investigate the origin of aftershocks using geometric reductionism made possible by the Non-Critical Precursory Accelerating Seismicity Theory postulate, which states that spatial density switches from δb0 for background seismicity to δbp for activated events (such as foreshocks, induced seismicity and here aftershocks) when the static stress field σ(r) exceeds the threshold σ(rA*) ∝ Δσ* with r the distance to source. The postulate explains the exponential spatial distribution (assuming that aftershocks fill a noisy fractal network within rA*) and aftershock production (assuming a constant stress drop) with K(M) = δbp.V(M), V being the volume of a rounded cuboid centred on the fault of length l ∝ exp(αM), and with radius rA*. Finally the observed stretching factor β ≈ 0.4 is explained topologically from the fractal dimension D ≈ 1.5.

  20. Investigation of the high-frequency attenuation parameter, κ (kappa), from aftershocks of the 2010 Mw 8.8 Maule, Chile earthquake

    USGS Publications Warehouse

    Neighbors, Corrie; Liao, E. J.; Cochran, Elizabeth S.; Funning, G. J.; Chung, A. I.; Lawrence, J. F.; Christensen, C. M.; Miller, M.; Belmonte, A.; Sepulveda, H. H. Andrés

    2014-01-01

    The Bío Bío region of Chile experienced a vigorous aftershock sequence following the 2010 February 27 Mw 8.8 Maule earthquake. The immediate aftershock sequence was captured by two temporary seismic deployments: the Quake Catcher Network Rapid Aftershock Mobilization Program (QCN RAMP) and the Incorporated Research Institutions for Seismology CHile Aftershock Mobilization Program (IRIS CHAMP). Here, we use moderate to large aftershocks (ML ≥ 4.0) occurring between 2010 March 1 and June 30 recorded by QCN RAMP and IRIS CHAMP stations to determine the spectral decay parameter, kappa (κ). First, we compare waveforms and κ estimates from the lower-resolution QCN stations to the IRIS CHAMP stations to ensure the QCN data are of sufficient quality. We find that QCN stations provide reasonable estimates of κ in comparison to traditional seismic sensors and provide valuable additional observations of local ground motion variation. Using data from both deployments, we investigate the variation in κ for the region to determine if κ is influenced primarily by local geological structure, path attenuation, or source properties (e.g. magnitude, mechanism and depth). Estimates of κ for the Bío Bío region range from 0.0022 to 0.0704 s with a mean of 0.0295 s and are in good agreement with κ values previously reported for similar tectonic environments. κ correlates with epicentral distance and, to a lesser degree, with source magnitude. We find little to no correlation between the site kappa, κ0, and mapped geology, although we were only able to compare the data to a low-resolution map of surficial geology. These results support an increasing number of studies that suggest κobservations can be attributed to a combination of source, path and site properties; additionally, measured κ are often highly scattered making it difficult to separate the contribution from each of these factors. Thus, our results suggest that contributions from the site

  1. Forecasting area of strong aftershock occurrence

    NASA Astrophysics Data System (ADS)

    Baranov, Sergey; Shebalin, Peter

    2016-04-01

    Forecasting an area of strong aftershock was never, at our knowledge, considered in terms of operational forecasting. Different declustering models exist to separate post-factum the aftershocks from "independent" events. Large number of studies discussed in previous years the form of the distribution of the aftershocks distances from the mainshock fault. Here we present results of our attempts to assimilate the above researches into a model that can be used in operational aftershock forecasting. Our study was based on data provided by ANSS catalog for 1980-2015. We tried more than 20 well known and suggested by ourselves models of aftershock areas to retrospective forecasting of strong aftershock areas. We tried the models based on data for 12 hours after a mainshock and estimated their forecast quality using special modification of L-test to achieve an optimal model. As a result of our study is a model that can be used in operational forecasting area of strong aftershocks. The research was supported by Russian Foundation for Basic Research (Project 16-05-00263A).

  2. Statistical Properties of Mine Tremor Aftershocks

    NASA Astrophysics Data System (ADS)

    Kgarume, T. E.; Spottiswoode, S. M.; Durrheim, R. J.

    2010-02-01

    Mine tremors and their aftershocks pose a risk to mine workers in the deep gold mines of South Africa. The statistical properties of mine-tremor aftershocks were investigated as part of an endeavour to assess the hazard and manage the risk. Data from two gold mines in the Carletonville mining district were used in the analysis. Main shocks were aligned in space and time and the aftershock sequences stacked and analysed. The aftershocks were found to satisfy Gutenberg-Richter scaling, with a b value close to 1. Aftershock activity diminished with time in accordance with the modified Omori law, with p values close to 1. However, the relationship between the main shock and its biggest aftershock violated Båths law, with Δ M L ≈ 1.9 for main shocks with M L < 3 and increasing for main shocks with M L > 3. The aftershock density was found to fall-off with distance as r -1.3, suggesting triggering by dynamic stress.

  3. 77 FR 47913 - The National Center for Mobility Management Under FTA's National Research Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-10

    ... Federal Transit Administration The National Center for Mobility Management Under FTA's National Research... Mobility (CCAM), is releasing an Announcement of Funding ] Opportunities (Announcement) to promote mobility... Program, plans to fund a National Center for Mobility Management (NCMM) which will carry-out activities...

  4. 77 FR 19408 - Dynamic Mobility Applications and Data Capture Management Programs; Notice of Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-30

    ... Dynamic Mobility Applications and Data Capture Management Programs; Notice of Public Meeting AGENCY: ITS... Data Capture and Management (DCM) and Dynamic Mobility Applications (DMA) programs in the Washington DC... to garner stakeholder feedback. About the Dynamic Mobility Application and Data Capture...

  5. [International academic mobility program in nursing experience report].

    PubMed

    de Oliveira, Mariana Gonçalves; Pagliuca, Lorita Marlena Freitag

    2012-03-01

    An experience of studying abroad or of academic exchange, really adds value to the professional and personal development of exchange students. This report aims to describe a student's experience in an international academic mobility program. It was developed from 2008 to 2009 in Brazil and Spain. The experiences, observations and activities of the student were emphasized believing that the training of students and researchers is not only restricted to the university and the students' home country, and that it is important to have possibilities of new experiences and differentiated knowledge. The conclusion is that this opportunity promoted a profound effect on psychological, cultural social and scientific development of the exchange student. PMID:22737814

  6. [International academic mobility program in nursing experience report].

    PubMed

    de Oliveira, Mariana Gonçalves; Pagliuca, Lorita Marlena Freitag

    2012-03-01

    An experience of studying abroad or of academic exchange, really adds value to the professional and personal development of exchange students. This report aims to describe a student's experience in an international academic mobility program. It was developed from 2008 to 2009 in Brazil and Spain. The experiences, observations and activities of the student were emphasized believing that the training of students and researchers is not only restricted to the university and the students' home country, and that it is important to have possibilities of new experiences and differentiated knowledge. The conclusion is that this opportunity promoted a profound effect on psychological, cultural social and scientific development of the exchange student.

  7. Aftershock patterns and main shock faulting

    USGS Publications Warehouse

    Mendoza, C.; Hartzell, S.H.

    1988-01-01

    We have compared aftershock patterns following several moderate to large earthquakes with the corresponding distributions of coseismic slip obtained from previous analyses of the recorded strong ground motion and teleseismic waveforms. Our results are consistent with a hypothesis of aftershock occurrence that requires a secondary redistribution of stress following primary failure on the earthquake fault. Aftershocks followng earthquakes examined in this study occur mostly outside of or near the edges of the source areas indicated by the patterns of main shock slip. The spatial distribution of aftershocks reflects either a continuation of slip in the outer regions of the areas of maximum coseismic displacement or the activation of subsidiary faults within the volume surrounding the boundaries of main shock rupture. -from Authors

  8. How Do Mobile Phone Diabetes Programs Drive Behavior Change?

    PubMed Central

    Nundy, Shantanu; Mishra, Anjuli; Hogan, Patrick; Lee, Sang Mee; Solomon, Marla C.; Peek, Monica E.

    2015-01-01

    Purpose The purpose of this study was to investigate the behavioral effects of a theory-driven, mobile phone–based intervention that combines automated text messaging and remote nursing, using an automated, interactive text messaging system. Methods This was a mixed methods observational cohort study. Study participants were members of the University of Chicago Health Plan (UCHP) who largely reside in a working-class, urban African American community. Surveys were conducted at baseline, 3 months (mid-intervention), and 6 months (postintervention) to test the hypothesis that the intervention would be associated with improvements in self-efficacy, social support, health beliefs, and self-care. In addition, in-depth individual interviews were conducted with 14 participants and then analyzed using the constant comparative method to identify new behavioral constructs affected by the intervention. Results The intervention was associated with improvements in 5 of 6 domains of self-care (medication taking, glucose monitoring, foot care, exercise, and healthy eating) and improvements in 1 or more measures of self-efficacy, social support, and health beliefs (perceived control). Qualitatively, participants reported that knowledge, attitudes, and ownership were also affected by the program. Together these findings were used to construct a new behavioral model. Conclusions This study’s findings challenge the prevailing assumption that mobile phones largely affect behavior change through reminders and support the idea that behaviorally driven mobile health interventions can address multiple behavioral pathways associated with sustained behavior change. PMID:25278512

  9. Aftershock Energy Distribution by Statistical Mechanics Approach

    NASA Astrophysics Data System (ADS)

    Daminelli, R.; Marcellini, A.

    2015-12-01

    The aim of our work is to research the most probable distribution of the energy of aftershocks. We started by applying one of the fundamental principles of statistical mechanics that, in case of aftershock sequences, it could be expressed as: the greater the number of different ways in which the energy of aftershocks can be arranged among the energy cells in phase space the more probable the distribution. We assume that each cell in phase space has the same possibility to be occupied, and that more than one cell in the phase space can have the same energy. Seeing that seismic energy is proportional to products of different parameters, a number of different combinations of parameters can produce different energies (e.g., different combination of stress drop and fault area can release the same seismic energy). Let us assume that there are gi cells in the aftershock phase space characterised by the same energy released ɛi. Therefore we can assume that the Maxwell-Boltzmann statistics can be applied to aftershock sequences with the proviso that the judgment on the validity of this hypothesis is the agreement with the data. The aftershock energy distribution can therefore be written as follow: n(ɛ)=Ag(ɛ)exp(-βɛ)where n(ɛ) is the number of aftershocks with energy, ɛ, A and β are constants. Considering the above hypothesis, we can assume g(ɛ) is proportional to ɛ. We selected and analysed different aftershock sequences (data extracted from Earthquake Catalogs of SCEC, of INGV-CNT and other institutions) with a minimum magnitude retained ML=2 (in some cases ML=2.6) and a time window of 35 days. The results of our model are in agreement with the data, except in the very low energy band, where our model resulted in a moderate overestimation.

  10. Laser safety considerations for a mobile laser program

    NASA Astrophysics Data System (ADS)

    Flor, Mary

    1997-05-01

    An increased demand for advanced laser technology, especially in the area of cutaneous and cosmetic procedures has prompted physicians to use mobile laser services. Utilization of a mobile laser service allows physicians to provide the latest treatments for their patients while minimizing overhead costs. The high capital expense of laser systems is often beyond the financial means of individual clinicians, group practices, free-standing clinics and smaller community hospitals. Historically rapid technology turnover with laser technology places additional risk which is unacceptable to many institutions. In addition, health care reform is mandating consolidation of equipment within health care groups to keep costs at a minimum. In 1994, Abbott Northwestern Hospital organized an in-house mobile laser technology service which employs a group of experienced laser specialists to deliver and support laser treatments for hospital outreach and other regional physicians and health care facilities. Many of the hospital's internal safety standards and policies are applicable to the mobile environment. A significant challenge is client compliance because of the delicate balance of managing risk while avoiding being viewed as a regulator. The clinics and hospitals are assessed prior to service to assure minimum laser safety standards for both the patient and the staff. A major component in assessing new sites is to inform them of applicable regulatory standards and their obligations to assure optimum laser safety. In service training is provided and hospital and procedures are freely shared to assist the client in establishing a safe laser environment. Physician and nursing preceptor programs are also made available.

  11. The Aftershock Risk Index - quantification of aftershock impacts during ongoing strong-seismic sequences

    NASA Astrophysics Data System (ADS)

    Schaefer, Andreas; Daniell, James; Khazai, Bijan; Wenzel, Friedemann

    2016-04-01

    The occurrence and impact of strong earthquakes often triggers the long-lasting impact of a seismic sequence. Strong earthquakes are generally followed by many aftershocks or even strong subsequently triggered ruptures. The Nepal 2015 earthquake sequence is one of the most recent examples where aftershocks significantly contributed to human and economic losses. In addition, rumours about upcoming mega-earthquakes, false predictions and on-going cycles of aftershocks induced a psychological burden on the society, which caused panic, additional casualties and prevented people from returning to normal life. This study shows the current phase of development of an operationalised aftershock intensity index, which will contribute to the mitigation of aftershock hazard. Hereby, various methods of earthquake forecasting and seismic risk assessments are utilised and an integration of the inherent aftershock intensity is performed. A spatio-temporal analysis of past earthquake clustering provides first-hand data about the nature of aftershock occurrence. Epidemic methods can additionally provide time-dependent variation indices of the cascading effects of aftershock generation. The aftershock hazard is often combined with the potential for significant losses through the vulnerability of structural systems and population. A historical database of aftershock socioeconomic effects from CATDAT has been used in order to calibrate the index based on observed impacts of historical events and their aftershocks. In addition, analytical analysis of cyclic behaviour and fragility functions of various building typologies are explored. The integration of many different probabilistic computation methods will provide a combined index parameter which can then be transformed into an easy-to-read spatio-temporal intensity index. The index provides daily updated information about the probability of the inherent seismic risk of aftershocks by providing a scalable scheme fordifferent aftershock

  12. Mechanism diversity of the loma prieta aftershocks and the mechanics of mainshock-aftershock interaction.

    PubMed

    Beroza, G C; Zoback, M D

    1993-01-01

    The diverse aftershock sequence of the 1989 Loma Prieta earthquake is inconsistent with conventional models of mainshock-aftershock interaction because the aftershocks do not accommodate mainshock-induced stress changes. Instead, the sense of slip of the aftershocks is consistent with failure in response to a nearly uniaxial stress field in which the maximum principal stress acts almost normal to the mainshock fault plane. This orientation implies that (i) stress drop in the mainshock was nearly complete, (ii) mainshock-induced decreases of fault strength helped were important in controlling the occurrence of after-shocks, and (iii) mainshock rupture was limited to those sections of the fault with preexisting shear stress available to drive fault slip.

  13. Operational Earthquake Forecasting of Aftershocks for New England

    NASA Astrophysics Data System (ADS)

    Ebel, J.; Fadugba, O. I.

    2015-12-01

    Although the forecasting of mainshocks is not possible, recent research demonstrates that probabilistic forecasts of expected aftershock activity following moderate and strong earthquakes is possible. Previous work has shown that aftershock sequences in intraplate regions behave similarly to those in California, and thus the operational aftershocks forecasting methods that are currently employed in California can be adopted for use in areas of the eastern U.S. such as New England. In our application, immediately after a felt earthquake in New England, a forecast of expected aftershock activity for the next 7 days will be generated based on a generic aftershock activity model. Approximately 24 hours after the mainshock, the parameters of the aftershock model will be updated using the observed aftershock activity observed to that point in time, and a new forecast of expected aftershock activity for the next 7 days will be issued. The forecast will estimate the average number of weak, felt aftershocks and the average expected number of aftershocks based on the aftershock statistics of past New England earthquakes. The forecast also will estimate the probability that an earthquake that is stronger than the mainshock will take place during the next 7 days. The aftershock forecast will specify the expected aftershocks locations as well as the areas over which aftershocks of different magnitudes could be felt. The system will use web pages, email and text messages to distribute the aftershock forecasts. For protracted aftershock sequences, new forecasts will be issued on a regular basis, such as weekly. Initially, the distribution system of the aftershock forecasts will be limited, but later it will be expanded as experience with and confidence in the system grows.

  14. Mobile Energy Laboratory energy-efficiency testing programs

    NASA Astrophysics Data System (ADS)

    Parker, G. B.; Currie, J. W.

    1991-09-01

    This report summarizes energy-efficiency testing activities applying the Mobile Energy Laboratory (MEL) testing capabilities during the first and second quarters of fiscal year (FY) 1991. The MELs, developed by the U.S. Department of Energy (DOE) Federal Energy Management Program (FEMP), are administered by Pacific Northwest Laboratory (PNL) and the Naval Energy and Environmental Support Activity (NEESA) for energy testing and energy conservation program support functions at Federal facilities. The using agencies principally fund MEL applications, while DOE/FEMP funds program administration and capability enhancement activities. This report fulfills the requirements established in Section 8 of the MEL Use Plan (PNL-6861) for semiannual reporting on energy-efficiency testing activities using the MEL capabilities. The MEL Use Committee, formally established in 1989, developed the MEL Use Plan and meets semiannually to establish priorities for energy-efficient testing applications using the MEL capabilities. The MEL Use Committee is composed of one representative each of the U.S. Department of Energy, U.S. Army, U.S. Air Force, U.S. Navy, and other Federal agencies.

  15. Mobile Energy Laboratory energy-efficiency testing programs

    SciTech Connect

    Parker, G.B.; Currie, J.W.

    1991-09-01

    This report summarizes energy-efficiency testing activities applying the Mobile Energy Laboratory (MEL) testing capabilities during the first and second quarters of fiscal year (FY) 1991. The MELs, developed by the US Department of Energy (DOE) Federal Energy Management Program (FEMP), are administered by Pacific Northwest Laboratory (PNL) and the Naval Energy and Environmental Support Activity (NEESA) for energy testing and energy conservation program support functions at federal facilities. The using agencies principally fund MEL applications, while DOE/FEMP funds program administration and capability enhancement activities. This report fulfills the requirements established in Section 8 of the MEL Use Plan (PNL-6861) for semiannual reporting on energy-efficiency testing activities using the MEL capabilities. The MEL Use Committee, formally established in 1989, developed the MEL Use Plan and meets semiannually to establish priorities for energy-efficient testing applications using the MEL capabilities. The MEL Use Committee is composed of one representative each of the US Department of Energy, US Army, US Air Force, US Navy, and other federal agencies.

  16. Mobile Energy Laboratory energy-efficiency testing programs

    SciTech Connect

    Parker, G B; Currie, J W

    1992-03-01

    This report summarizes energy-efficiency testing activities applying the Mobile Energy Laboratory (MEL) testing capabilities during the third and fourth quarters of fiscal year (FY) 1991. The MELs, developed by the US Department of Energy (DOE) Federal Energy Management Program (FEMP), are administered by Pacific Northwest Laboratory (PNL) and the Naval Energy and Environmental Support Activity (NEESA) for energy testing and energy conservation program support functions at federal facilities. The using agencies principally fund MEL applications, while DOE/FEMP funds program administration and capability enhancement activities. This report fulfills the requirements established in Section 8 of the MEL Use Plan (PNL-6861) for semi-annual reporting on energy-efficiency testing activities using the MEL capabilities. The MEL Use Committee, formally established in 1989, developed the MEL Use Plan and meets semi-annually to establish priorities for energy-efficient testing applications using the MEL capabilities. The MEL Use Committee is composed of one representative each of the US Department of Energy, US Army, US Air Force, US Navy, and other federal agencies.

  17. Discrete neural dynamic programming in wheeled mobile robot control

    NASA Astrophysics Data System (ADS)

    Hendzel, Zenon; Szuster, Marcin

    2011-05-01

    In this paper we propose a discrete algorithm for a tracking control of a two-wheeled mobile robot (WMR), using an advanced Adaptive Critic Design (ACD). We used Dual-Heuristic Programming (DHP) algorithm, that consists of two parametric structures implemented as Neural Networks (NNs): an actor and a critic, both realized in a form of Random Vector Functional Link (RVFL) NNs. In the proposed algorithm the control system consists of the DHP adaptive critic, a PD controller and a supervisory term, derived from the Lyapunov stability theorem. The supervisory term guaranties a stable realization of a tracking movement in a learning phase of the adaptive critic structure and robustness in face of disturbances. The discrete tracking control algorithm works online, uses the WMR model for a state prediction and does not require a preliminary learning. Verification has been conducted to illustrate the performance of the proposed control algorithm, by a series of experiments on the WMR Pioneer 2-DX.

  18. 75 FR 56651 - ITS Joint Program Office; Trucking Industry Mobility & Technology Coalition Annual Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-16

    ... ITS Joint Program Office; Trucking Industry Mobility & Technology Coalition Annual Meeting AGENCY... Trucking Industry Mobility & Technology Coalition (TIMTC) Annual ] Meeting will be held October 18-19, 2010... updates on trucking industry initiatives that improve the industry's safety and mobility. Send...

  19. Scaling Relations Between Mainshock Source Parameters and Aftershock Distributions for Use in Aftershock Forecasting

    NASA Astrophysics Data System (ADS)

    Donovan, J.; Jordan, T. H.

    2010-12-01

    Aftershocks are often used to delineate the mainshock rupture zone retrospectively. In aftershock forecasting on the other hand, the problem is to use mainshock rupture area to determine the aftershock zone prospectively. The procedures for this type of prediction are not as well developed and have been restricted to simple parameterizations such as the Utsu-Seki (1955) scaling relation between mainshock energy and aftershock area (Ogata and Zhueng, 2006). With a focus on improving current forecasting methods, we investigate the relationship between spatial source parameters that can be rapidly computed (spatial centroid and characteristic dimensions) and corresponding spatial measures of the aftershock distribution. For a set of about 30 large events, we either extracted source parameters from the McGuire et al (2002) finite moment tensor (FMT) catalog, or computed them from the online SRCMOD database (Mai, 2004). We identified aftershocks with windowing and scale-free methods, and computed both L1 and L2 measures of their distributions. Our comparisons produce scaling relations among the characteristic dimensions that can be used to initiate aftershock forecasts. By using rapidly-determined source parameters, we can decrease the forecasting latency and thus improve the probability gain of the forecasting methods.

  20. Active object programming for military autonomous mobile robot software prototyping

    NASA Astrophysics Data System (ADS)

    Cozien, Roger F.

    2001-10-01

    While designing mobile robots, we do think that the prototyping phase is really critical. Good and clever choices have to be made. Indeed, we may not easily upgrade such robots, and most of all, when the robot is on its own, any change in both the software and the physical body is going to be very difficult, if not impossible. Thus, a great effort has to be made when prototyping the robot. Furthermore, I think that the kind of programming is very important. If your programming model is not expressive enough, you may experience a great deal of difficulties to add all the features you want, in order to give your robot reactiveness and decision making autonomy. Moreover, designing, and prototyping the on-board software of a reactive robot brings other difficulties. A reactive robot does not include any matter of rapidity. A reactive system is a system able to respond to a huge panel of situations of which it does not have the schedule. In other words, for instance, the robot does not know when a particular situation may occur, and overall, what it would be doing at this time, and what would be its internal state. This kind of robot must be able to take a decision and to act even if they do not have all the contextual information. To do so, we use a computer language named oRis featuring object and active object oriented programming, but also parallel and dynamic code, (the code can be changed during its own execution). This last point has been made possible because oRis is fully interpreted. However oRis may call fully compiled code, but also Prolog and Java code. An oRis program may be distributed on several computers using TCP/IP network connections. The main issue in this paper is to show how active objet oriented programming, as a modern extension of object oriented programming, may help us in designing autonomous mobile robots. Based on a fully parallel software programming, an active object code allows us to give many features to a robot, and to easily solve

  1. Active objects programming for military autonomous mobile robots software prototyping

    NASA Astrophysics Data System (ADS)

    Cozien, Roger F.

    2001-09-01

    While designing mobile robots, we do think that the prototyping phase is really critical. Good and clever choices have to be made. Indeed, we may not easily upgrade such robots, and most of all, when the robot is on its own, any change in both the software and the physical body is going to be very difficult, if not impossible. Thus, a great effort has to be made when prototyping the robot. Furthermore, I think that the kind of programming is very important. If your programming model is not expressive enough, you may experience a great deal of difficulties to add all the features you want, in order to give your robot reactiveness and decision making autonomy. Moreover, designing, and prototyping the on-board software of a reactive robot brings other difficulties. A reactive robot does not include any matter of rapidity. A reactive system is a system able to respond to a huge pannel of situations of which it does not have the schedule. In other words, for instance, the robot does not know when a particular situation may occur, and overall, what it would be doing at this time, and what would be its internal state. This kind of robot must be able to take a decision and to act even if they do not have all the contextual information. To do so, we use a computer language named oRis featuring object and active object oriented programming, but also parallel and dynamic code, (the code can be changed during its own execution). This last point has been made possible because oRis is fully interpreted. However oRis may call fully compiled code, but also Prolog and Java code. An oRis program may be distributed on several computers using TCP/IP network connections. The main issue in this paper is to show how active objet oriented programming, as a modern extension of object oriented programming, may help us in designing autonomous mobile robots. Based on a fully parallel software programming, an active object code allows us to give many features to a robot, and to easily solve

  2. Intermediate-term forecasting of aftershocks from an early aftershock sequence: Bayesian and ensemble forecasting approaches

    NASA Astrophysics Data System (ADS)

    Omi, Takahiro; Ogata, Yosihiko; Hirata, Yoshito; Aihara, Kazuyuki

    2015-04-01

    Because aftershock occurrences can cause significant seismic risks for a considerable time after the main shock, prospective forecasting of the intermediate-term aftershock activity as soon as possible is important. The epidemic-type aftershock sequence (ETAS) model with the maximum likelihood estimate effectively reproduces general aftershock activity including secondary or higher-order aftershocks and can be employed for the forecasting. However, because we cannot always expect the accurate parameter estimation from incomplete early aftershock data where many events are missing, such forecasting using only a single estimated parameter set (plug-in forecasting) can frequently perform poorly. Therefore, we here propose Bayesian forecasting that combines the forecasts by the ETAS model with various probable parameter sets given the data. By conducting forecasting tests of 1 month period aftershocks based on the first 1 day data after the main shock as an example of the early intermediate-term forecasting, we show that the Bayesian forecasting performs better than the plug-in forecasting on average in terms of the log-likelihood score. Furthermore, to improve forecasting of large aftershocks, we apply a nonparametric (NP) model using magnitude data during the learning period and compare its forecasting performance with that of the Gutenberg-Richter (G-R) formula. We show that the NP forecast performs better than the G-R formula in some cases but worse in other cases. Therefore, robust forecasting can be obtained by employing an ensemble forecast that combines the two complementary forecasts. Our proposed method is useful for a stable unbiased intermediate-term assessment of aftershock probabilities.

  3. Aftershock production rate of driven viscoelastic interfaces.

    PubMed

    Jagla, E A

    2014-10-01

    We study analytically and by numerical simulations the statistics of the aftershocks generated after large avalanches in models of interface depinning that include viscoelastic relaxation effects. We find in all the analyzed cases that the decay law of aftershocks with time can be understood by considering the typical roughness of the interface and its evolution due to relaxation. In models where there is a single viscoelastic relaxation time there is an exponential decay of the number of aftershocks with time. In models in which viscoelastic relaxation is wave-vector dependent we typically find a power-law dependence of the decay rate that is compatible with the Omori law. The factors that determine the value of the decay exponent are analyzed.

  4. Identifying wound prevalence using the Mobile Wound Care program.

    PubMed

    Walker, Judi; Cullen, Marianne; Chambers, Helen; Mitchell, Eleanor; Steers, Nicole; Khalil, Hanan

    2014-06-01

    Measuring the prevalence of wounds within health care systems is a challenging and complex undertaking. This is often compounded by the clinicians' training, the availability of the required data to collect, incomplete documentation and lack of reporting of this type of data across the various health care settings. To date, there is little published data on wound prevalence across regions or states. This study aims to identify the number and types of wounds treated in the Gippsland area using the Mobile Wound Care (MWC™) program. The MWC program has enabled clinicians in Gippsland to collect data on wounds managed by district nurses from four health services. The main outcomes measured were patient characteristics, wound characteristics and treatment characteristics of wounds in Gippsland. These data create several clinical and research opportunities. The identification of predominant wound aetiologies in Gippsland provides a basis on which to determine a regional wound prospective and the impact of the regional epidemiology. Training that incorporates best practice guidelines can be tailored to the most prevalent wound types. Clinical pathways that encompass the Australian and New Zealand clinical practice guidelines for the management of venous leg ulcers can be introduced and the clinical and economical outcomes can be quantitatively measured. The MWC allows healing times (days) to be benchmarked both regionally and against established literature, for example, venous leg ulcers.

  5. How Long is an Aftershock Sequence?

    NASA Astrophysics Data System (ADS)

    Godano, Cataldo; Tramelli, Anna

    2016-07-01

    The occurrence of a mainschok is always followed by aftershocks spatially distributed within the fault area. The aftershocks rate decay with time is described by the empirical Omori law which was inferred by catalogues analysis. The sequences discrimination within catalogues is not a straightforward operation, especially for low-magnitude mainshocks. Here, we describe the rate decay of the Omori law obtained using different sequence discrimination tools and we discover that, when the background seismicity is excluded, the sequences tend to last for the temporal extension of the catalogue.

  6. Processing Aftershock Sequences Using Waveform Correlation

    NASA Astrophysics Data System (ADS)

    Resor, M. E.; Procopio, M. J.; Young, C. J.; Carr, D. B.

    2008-12-01

    For most event monitoring systems, the objective is to keep up with the flow of incoming data, producing a bulletin with some modest, relatively constant, time delay after present time, often a period of a few hours or less. Because the association problem scales exponentially and not linearly with the number of detections, a dramatic increase in seismicity due to an aftershock sequence can easily cause the bulletin delay time to increase dramatically. In some cases, the production of a bulletin may cease altogether, until the automatic system can catch up. For a nuclear monitoring system, the implications of such a delay could be dire. Given the expected similarity between a mainshock and aftershocks, it has been proposed that waveform correlation may provide a powerful means to simultaneously increase the efficiency of processing aftershock sequences, while also lowering the detection threshold and improving the quality of the event solutions. However, many questions remain unanswered. What are the key parameters for achieving the best correlations between waveforms (window length, filtering, etc.), and are they sequence-dependent? What is the overall percentage of similar events in an aftershock sequence, i.e. what is the maximum level of efficiency that a waveform correlation could be expected to achieve? Finally, how does this percentage of events vary among sequences? Using data from the aftershock sequence for the December 26, 2004 Mw 9.1 Sumatra event, we investigate these issues by building and testing a prototype waveform correlation event detection system that automatically expands its library of known events as new signatures are indentified in the aftershock sequence (by traditional signal detection and event processing). Our system tests all incoming data against this dynamic library, thereby identify any similar events before traditional processing takes place. In the region surrounding the Sumatra event, the NEIC EDR contains 4997 events in the 9

  7. Computer program for afterheat temperature distribution for mobile nuclear power plant

    NASA Technical Reports Server (NTRS)

    Parker, W. G.; Vanbibber, L. E.

    1972-01-01

    ESATA computer program was developed to analyze thermal safety aspects of post-impacted mobile nuclear power plants. Program is written in FORTRAN 4 and designed for IBM 7094/7044 direct coupled system.

  8. HIPAA Compliance with Mobile Devices Among ACGME Programs.

    PubMed

    McKnight, Randall; Franko, Orrin

    2016-05-01

    To analyze self-reported HIPAA compliance with mobile technologies among residents, fellows, and attendings at ACGME training programs. A digital survey was sent to 678 academic institutions over a 1-month period. 2427 responses were analyzed using Chi-squared tests for independence. Post-hoc Bonferroni correction was applied for all comparisons between training levels, clinical setting, and specialty. 58 % of all residents self-report violating HIPAA by sharing protected health information (PHI) via text messaging with 27 % reporting they do it "often" or "routinely" compared to 15-19 % of attendings. For all specialties, 35 % of residents use text messaging photo or video sharing with PHI. Overall, 5 % of respondents "often" or "routinely" used HIPAA compliant (HCApps) with no significant differences related to training level. 20 % of residents admitted to using non-encrypted email at some point. 53 % of attendings and 41 % of residents utilized encrypted email routinely. Physicians from surgical specialties compared to non-surgical specialties demonstrated higher rates of HIPAA violations with SMS use (35 % vs. 17.7 %), standard photo/video messages (16.3 % vs. 4.7 %), HCApps (10.9 % vs. 4.9 %), and non-HCApps (5.6 % vs 1.5 %). The most significant barriers to complying with HIPAA were inconvenience (58 %), lack of knowledge (37 %), unfamiliarity (34 %), inaccessible (29 %) and habit (24 %). Medical professionals must acknowledge that despite laws to protect patient confidentiality in the era of mobile technology, over 50 % of current medical trainees knowingly violate these rules regularly despite the threat of severe consequences. The medical community must further examine the reason for these inconsistencies and work towards possible solutions. PMID:27079578

  9. Use of Mobile Technology for Monitoring and Evaluation in International Health and Development Programs

    ERIC Educational Resources Information Center

    Bruce, Kerry

    2013-01-01

    Background: Mobile phones and other technologies are widely used in health programming in developing countries, many introduced by international nongovernmental organizations (INGOs) to accelerate data collection. This research examined: How are INGOs adopting the innovation of mobile technology into M&E systems for health care programs in…

  10. Upward Mobility Programs in the Service Sector for Disadvantaged and Dislocated Workers. Volume I: Final Report.

    ERIC Educational Resources Information Center

    Tao, Fumiyo; And Others

    Upward mobility programs in the service sector for low-skilled, economically disadvantaged, and dislocated or displaced workers promote employment security, career development, and productivity. Two basic types of upward mobility programs are basic and job-specific skills training. Although 60-80 percent of all employer-sponsored formal training…

  11. Investigating the Effectiveness of a Comprehensive Literacy Coaching Program in Schools with High Teacher Mobility

    ERIC Educational Resources Information Center

    Matsumura, Lindsay Clare; Garnier, Helen E.; Correnti, Richard; Junker, Brian; Bickel, Donna DiPrima

    2010-01-01

    Teacher mobility is a factor that impacts schoolwide implementation of professional development programs. In this article, we present interim results of a longitudinal randomized field trial of a comprehensive literacy coaching program (Content-Focused Coaching, CFC) for improving instruction and learning in schools with high teacher mobility. We…

  12. Initial Evaluation of a Mobile Scaffolding Application That Seeks to Support Novice Learners of Programming

    ERIC Educational Resources Information Center

    Mbogo, Chao; Blake, Edwin; Suleman, Hussein

    2014-01-01

    The aim of this paper is to explore the use of an application that scaffolds the constructions of programs on a mobile device. The application was developed to support novice learners of programming outside the classroom. This paper reports on results of a first experiment conducted to evaluate the mobile application. The main research questions…

  13. Mobile soak pits improve spray team mobility, productivity and safety of PMI malaria control programs.

    PubMed

    Mitchell, David F; Brown, Annie S; Bouare, Sory Ibrahima; Belemvire, Allison; George, Kristen; Fornadel, Christen; Norris, Laura; Longhany, Rebecca; Chandonait, Peter J

    2016-09-15

    In the President's Malaria Initiative (PMI)-funded Africa Indoor Residual Spraying Project (AIRS), end-of-day clean-up operations require the safe disposal of wash water resulting from washing the exterior of spray tanks and spray operators' personal protective equipment. Indoor residual spraying (IRS) programs typically use soak pits - large, in-ground filters - to adsorb, filter and then safely degrade the traces of insecticide found in the wash water. Usually these soak pits are permanent installations serving 30 or more operators, located in a central area that is accessible to multiple spray teams at the end of their workday. However, in remote areas, it is often impractical for teams to return to a central soak pit location for cleanup. To increase operational efficiency and improve environmental compliance, the PMI AIRS Project developed and tested mobile soak pits (MSP) in the laboratory and in field applications in Madagascar, Mali, Senegal, and Ethiopia where the distance between villages can be substantial and the road conditions poor. Laboratory testing confirmed the ability of the easily-assembled MSP to reduce effluent concentrations of two insecticides (Actellic 300-CS and Ficam VC) used by the PMI AIRS Project, and to generate the minimal practicable environmental "footprint" in these remote areas. Field testing in the Mali 2014 IRS campaign demonstrated ease of installation and use, resulted in improved and more consistent standards of clean-up, decreased transportation requirements, improved spray team working conditions, and reduced potential for operator exposure to insecticide. PMID:27341285

  14. The Prediction of Spatial Aftershock Probabilities (PRESAP)

    NASA Astrophysics Data System (ADS)

    McCloskey, J.

    2003-12-01

    It is now widely accepted that the goal of deterministic earthquake prediction is unattainable in the short term and may even be forbidden by nonlinearity in the generating dynamics. This nonlinearity does not, however, preclude the estimation of earthquake probability and, in particular, how this probability might change in space and time; earthquake hazard estimation might be possible in the absence of earthquake prediction. Recently, there has been a major development in the understanding of stress triggering of earthquakes which allows accurate calculation of the spatial variation of aftershock probability following any large earthquake. Over the past few years this Coulomb stress technique (CST) has been the subject of intensive study in the geophysics literature and has been extremely successful in explaining the spatial distribution of aftershocks following several major earthquakes. The power of current micro-computers, the great number of local, telemeter seismic networks, the rapid acquisition of data from satellites coupled with the speed of modern telecommunications and data transfer all mean that it may be possible that these new techniques could be applied in a forward sense. In other words, it is theoretically possible today to make predictions of the likely spatial distribution of aftershocks in near-real-time following a large earthquake. Approximate versions of such predictions could be available within, say, 0.1 days after the mainshock and might be continually refined and updated over the next 100 days. The European Commission has recently provided funding for a project to assess the extent to which it is currently possible to move CST predictions into a practically useful time frame so that low-confidence estimates of aftershock probability might be made within a few hours of an event and improved in near-real-time, as data of better quality become available over the following day to tens of days. Specifically, the project aim is to assess the

  15. Aftershock Decay Rates in the Iranian Plateau

    NASA Astrophysics Data System (ADS)

    Ommi, S.; Zafarani, H.; Zare, M.

    2016-07-01

    Motivated by the desire to have more information following the occurrence of damaging events, the main purpose of this article is to study aftershock sequence parameters in the Iranian plateau. To this end, the catalogue of the Iranian earthquakes between 2002 to the end of 2013 has been collected and homogenized among which 15 earthquakes have been selected to study their aftershock decay rates. For different tectonic provinces, the completeness magnitudes ( M c) of the earthquake catalogue have been calculated in different time intervals. Also, the M c variability in spatial and temporal windows has been determined for each selected event. For major Iranian earthquakes, catalogue of aftershocks has been collected thanks to three declustering methods: first, the classical windowing method of Gardner and Knopoff (Bull Seismol Soc Am 64:1363-1367, 1974); second, a modified version of this using spatial windowing based on the Wells and Coppersmith (Bull Seismol Soc Am 84:974-1002, 1994) relations; and third, the Burkhard and Grünthal (Swiss J Geosci 102:149-188, 2009) scheme. Effects of the temporal windows also have been investigated using the time periods of 1 month, 100 days, and 1 year in the declustering method of Gardner and Knopoff (Bull Seismol Soc Am 64:1363-1367, 1974). In the next step, the modified Omori law coefficients have been calculated for the 15 selected earthquakes. The calibrated regional generic model describing the temporal and magnitude distribution of aftershocks is of interest for time-dependent seismic hazard forecasts. The regional characteristics of the aftershock decay rates have been studied for the selected Iranian earthquakes in the Alborz, Zagros and Central Iran regions considering their different seismotectonics regimes. However, due to the lack of sufficient data, no results have been reported for the Kopeh-Dagh and Makran seismotectonic regions.

  16. Adaptive forecasting of aftershock activity after the main shock

    NASA Astrophysics Data System (ADS)

    Omi, Takahiro; Ogata, Yosihiko; Hirata, Yoshito; Aihara, Kazuyuki

    2014-05-01

    Forecasting aftershock activity is useful to reduce seismic risks in the affected area after the main shock. The difficulties to forecast aftershocks are (i) a forecasting model should be tailored to each aftershock sequence because the statistical property varies greatly according to an individual aftershock sequence and (ii) the forecasting model has to be estimated from highly deficient data where a significant fraction of early small aftershocks are missing from seismic records. To overcome this difficulty, we have been developing a statistical model to deal with incompletely detected aftershocks, in which the detection rate of aftershocks is sequentially estimated in a state-space modeling approach. Our method enables us to robustly estimate the forecasting model of underlying aftershocks including not only observed aftershocks but also missing ones from the incomplete catalog. We show that the Omori-Utsu formula can be well estimated only from a few hours of the data, and then it can be revised by the epidemic type aftershock sequence (ETAS) model to adaptively forecast an aftershock sequence with the individual cascading feature as the data size increases in real-time. We demonstrate that how these estimated models can effectively forecast the aftershock activity. We also discuss how these models can be implemented in an operational system for earthquake forecasting. References: T. Omi, Y. Ogata, Y. Hirata, and K. Aihiara, "Forecasting large aftershocks within one day after the main shock", Scientific Reports, 3, 2218 (2013). T. Omi, Y. Ogata, Y. Hirata, and K. Aihiara, "Estimating the ETAS model from an early aftershock sequence", (In submission).

  17. Aftershock Characteristics as a Means of Discriminating Explosions from Earthquakes

    SciTech Connect

    Ford, S R; Walter, W R

    2009-05-20

    The behavior of aftershock sequences around the Nevada Test Site in the southern Great Basin is characterized as a potential discriminant between explosions and earthquakes. The aftershock model designed by Reasenberg and Jones (1989, 1994) allows for a probabilistic statement of earthquake-like aftershock behavior at any time after the mainshock. We use this model to define two types of aftershock discriminants. The first defines M{sub X}, or the minimum magnitude of an aftershock expected within a given duration after the mainshock with probability X. Of the 67 earthquakes with M > 4 in the study region, 63 of them produce an aftershock greater than M{sub 99} within the first seven days after a mainshock. This is contrasted with only six of 93 explosions with M > 4 that produce an aftershock greater than M{sub 99} for the same period. If the aftershock magnitude threshold is lowered and the M{sub 90} criteria is used, then no explosions produce an aftershock greater than M{sub 90} for durations that end more than 17 days after the mainshock. The other discriminant defines N{sub X}, or the minimum cumulative number of aftershocks expected for given time after the mainshock with probability X. Similar to the aftershock magnitude discriminant, five earthquakes do not produce more aftershocks than N{sub 99} within 7 days after the mainshock. However, within the same period all but one explosion produce less aftershocks then N{sub 99}. One explosion is added if the duration is shortened to two days after than mainshock. The cumulative number aftershock discriminant is more reliable, especially at short durations, but requires a low magnitude of completeness for the given earthquake catalog. These results at NTS are quite promising and should be evaluated at other nuclear test sites to understand the effects of differences in the geologic setting and nuclear testing practices on its performance.

  18. Assessment and Assimilation: A Program for Schools Challenged with Mobility

    ERIC Educational Resources Information Center

    Power, Donna

    2012-01-01

    Student mobility is the process of describing how children move from one school to another for reasons other than promotion. Highly mobile students are defined as students who move six or more times during their school career. Schools that experience the constant flow of students moving in and out struggle with delivering consistent and effective…

  19. The aftershock signature of supershear earthquakes.

    PubMed

    Bouchon, Michel; Karabulut, Hayrullah

    2008-06-01

    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. PMID:18535239

  20. The aftershock signature of supershear earthquakes.

    PubMed

    Bouchon, Michel; Karabulut, Hayrullah

    2008-06-01

    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.

  1. The Mw 5.8 Virginia Earthquake of August 23, 2011 and its Aftershocks: A Shallow High Stress Drop Event

    NASA Astrophysics Data System (ADS)

    Ellsworth, W. L.; Imanishi, K.; Luetgert, J. H.; Kruger, J.; Hamilton, J.

    2011-12-01

    We analyze the hypocentral distribution and source parameters of the aftershocks of the Virginia Earthquake of August 23, 2011 using a temporary array of telemetered instruments deployed within 20 km of the main shock. Our data come from four USGS NetQuakes accelerometers and seven IRIS/PASSCAL seismometers that were established within a few days of the earthquake. Aftershock seismograms at these near-source stations are characterized by impulsive, high-frequency P and S phases at most sites. In addition, we use the five closest permanent stations (60 - 310 km distance) to analyze the main shock. Hypocenters, crustal velocity model and station corrections were determined using the program VELEST (Kissling, et al, 1994). The aftershocks define a 10-km-long, N 30 degree E striking, 45 degree ESE dipping fault. This fault plane agrees well with the USGS moment tensor solutions for the main shock. Aftershock depths range from 2.5 to 8 km, placing the sequence in the Cambrian metamorphic rocks of the Eastern Piedmont thrust sheet. We relocated the main shock relative to a well-located Mw 3.5 aftershock using the P-wave arrival times at the five permanent stations. The main shock epicenter lies in the middle of the aftershock zone. Its focal depth, although not well constrained, is similar to the aftershocks. A crustal-scale seismic reflection profile was acquired by the USGS in 1981 along I-64 just 4 km southwest of the nearest aftershocks. This profile runs nearly parallel to the dip direction of the aftershock zone and has been interpreted to contain many ESE-dipping reverse faults in the allochthonous upper crust (Harris et al., 1986; Pratt, et al., 1988). When projected onto the reflection profile the aftershocks locate within a relatively non-reflective zone bounded above and below by prominent bands of more shallowly dipping reflectors reported by Pratt et al. (1988) raising the question whether or not the earthquake reactivated a pre-existing fault. Seismic

  2. Aftershocks in a frictional earthquake model.

    PubMed

    Braun, O M; Tosatti, Erio

    2014-09-01

    Inspired by spring-block models, we elaborate a "minimal" physical model of earthquakes which reproduces two main empirical seismological laws, the Gutenberg-Richter law and the Omori aftershock law. Our point is to demonstrate that the simultaneous incorporation of aging of contacts in the sliding interface and of elasticity of the sliding plates constitutes the minimal ingredients to account for both laws within the same frictional model. PMID:25314453

  3. Aftershocks in a frictional earthquake model.

    PubMed

    Braun, O M; Tosatti, Erio

    2014-09-01

    Inspired by spring-block models, we elaborate a "minimal" physical model of earthquakes which reproduces two main empirical seismological laws, the Gutenberg-Richter law and the Omori aftershock law. Our point is to demonstrate that the simultaneous incorporation of aging of contacts in the sliding interface and of elasticity of the sliding plates constitutes the minimal ingredients to account for both laws within the same frictional model.

  4. Forecasting large aftershocks within one day after the main shock.

    PubMed

    Omi, Takahiro; Ogata, Yosihiko; Hirata, Yoshito; Aihara, Kazuyuki

    2013-01-01

    Forecasting the aftershock probability has been performed by the authorities to mitigate hazards in the disaster area after a main shock. However, despite the fact that most of large aftershocks occur within a day from the main shock, the operational forecasting has been very difficult during this time-period due to incomplete recording of early aftershocks. Here we propose a real-time method for efficiently forecasting the occurrence rates of potential aftershocks using systematically incomplete observations that are available in a few hours after the main shocks. We demonstrate the method's utility by retrospective early forecasting of the aftershock activity of the 2011 Tohoku-Oki Earthquake of M9.0 in Japan. Furthermore, we compare the results by the real-time data with the compiled preliminary data to examine robustness of the present method for the aftershocks of a recent inland earthquake in Japan.

  5. Forecasting large aftershocks within one day after the main shock

    PubMed Central

    Omi, Takahiro; Ogata, Yosihiko; Hirata, Yoshito; Aihara, Kazuyuki

    2013-01-01

    Forecasting the aftershock probability has been performed by the authorities to mitigate hazards in the disaster area after a main shock. However, despite the fact that most of large aftershocks occur within a day from the main shock, the operational forecasting has been very difficult during this time-period due to incomplete recording of early aftershocks. Here we propose a real-time method for efficiently forecasting the occurrence rates of potential aftershocks using systematically incomplete observations that are available in a few hours after the main shocks. We demonstrate the method's utility by retrospective early forecasting of the aftershock activity of the 2011 Tohoku-Oki Earthquake of M9.0 in Japan. Furthermore, we compare the results by the real-time data with the compiled preliminary data to examine robustness of the present method for the aftershocks of a recent inland earthquake in Japan. PMID:23860594

  6. Triggering of earthquake aftershocks by dynamic stresses

    USGS Publications Warehouse

    Kilb, Debi; Gomberg, J.; Bodin, P.

    2000-01-01

    It is thought that small 'static' stress changes due to permanent fault displacement can alter the likelihood of, or trigger, earthquakes on nearby faults. Many studies of triggering in the nearfield, particularly of aftershocks, rely on these static changes as the triggering agent and consider them only in terms of equivalent changes in the applied load on the fault. Here we report a comparison of the aftershock pattern of the moment magnitude MW = 7.3 Landers earthquake, not only with static stress changes but also with transient, oscillatory stress changes transmitted as seismic waves (that is, 'dynamic' stresses). Dynamic stresses do not permanently change the applied load and thus can trigger earthquakes only by altering the mechanical state or properties of the fault zone. These dynamically weakened faults may fail after the seismic waves have passed by, and might even cause earthquakes that would not otherwise have occurred. We find similar asymmetries in the aftershock and dynamic stress patterns, the latter being due to rupture propagation, whereas the static stress changes lack this asymmetry. Previous studies have shown that dynamic stresses can promote failure at remote distances, but here we show that they can also do so nearby.

  7. Triggering of earthquake aftershocks by dynamic stresses.

    PubMed

    Kilb, D; Gomberg, J; Bodin, P

    2000-11-30

    It is thought that small 'static' stress changes due to permanent fault displacement can alter the likelihood of, or trigger, earthquakes on nearby faults. Many studies of triggering in the near-field, particularly of aftershocks, rely on these static changes as the triggering agent and consider them only in terms of equivalent changes in the applied load on the fault. Here we report a comparison of the aftershock pattern of the moment magnitude Mw = 7.3 Landers earthquake, not only with static stress changes but also with transient, oscillatory stress changes transmitted as seismic waves (that is, 'dynamic' stresses). Dynamic stresses do not permanently change the applied load and thus can trigger earthquakes only by altering the mechanical state or properties of the fault zone. These dynamically weakened faults may fail after the seismic waves have passed by, and might even cause earthquakes that would not otherwise have occurred. We find similar asymmetries in the aftershock and dynamic stress patterns, the latter being due to rupture propagation, whereas the static stress changes lack this asymmetry. Previous studies have shown that dynamic stresses can promote failure at remote distances, but here we show that they can also do so nearby.

  8. Do aftershock probabilities decay with time?

    USGS Publications Warehouse

    Michael, Andrew J.

    2012-01-01

    So, do aftershock probabilities decay with time? Consider a thought experiment in which we are at the time of the mainshock and ask how many aftershocks will occur a day, week, month, year, or even a century from now. First we must decide how large a window to use around each point in time. Let's assume that, as we go further into the future, we are asking a less precise question. Perhaps a day from now means 1 day 10% of a day, a week from now means 1 week 10% of a week, and so on. If we ignore c because it is a small fraction of a day (e.g., Reasenberg and Jones, 1989, hereafter RJ89), and set p = 1 because it is usually close to 1 (its value in the original Omori law), then the rate of earthquakes (K=t) decays at 1=t. If the length of the windows being considered increases proportionally to t, then the number of earthquakes at any time from now is the same because the rate decrease is canceled by the increase in the window duration. Under these conditions we should never think "It's a bit late for this to be an aftershock."

  9. Model for the Distribution of Aftershock Interoccurrence Times

    SciTech Connect

    Shcherbakov, Robert; Yakovlev, Gleb; Rundle, John B.; Turcotte, Donald L.

    2005-11-18

    In this work the distribution of interoccurrence times between earthquakes in aftershock sequences is analyzed and a model based on a nonhomogeneous Poisson (NHP) process is proposed to quantify the observed scaling. In this model the generalized Omori's law for the decay of aftershocks is used as a time-dependent rate in the NHP process. The analytically derived distribution of interoccurrence times is applied to several major aftershock sequences in California to confirm the validity of the proposed hypothesis.

  10. Model for the distribution of aftershock interoccurrence times.

    PubMed

    Shcherbakov, Robert; Yakovlev, Gleb; Turcotte, Donald L; Rundle, John B

    2005-11-18

    In this work the distribution of interoccurrence times between earthquakes in aftershock sequences is analyzed and a model based on a nonhomogeneous Poisson (NHP) process is proposed to quantify the observed scaling. In this model the generalized Omori's law for the decay of aftershocks is used as a time-dependent rate in the NHP process. The analytically derived distribution of interoccurrence times is applied to several major aftershock sequences in California to confirm the validity of the proposed hypothesis.

  11. Implementing a Mobility Program to Minimize Post-Intensive Care Syndrome.

    PubMed

    Hopkins, Ramona O; Mitchell, Lorie; Thomsen, George E; Schafer, Michele; Link, Maggie; Brown, Samuel M

    2016-01-01

    Immobility in the intensive care unit (ICU) is associated with neuromuscular weakness, post-intensive care syndrome, functional limitations, and high costs. Early mobility-based rehabilitation in the ICU is feasible and safe. Mobility-based rehabilitation varied widely across 5 ICUs in 1 health care system, suggesting a need for continuous training and evaluation to maintain a strong mobility-based rehabilitation program. Early mobility-based rehabilitation shortens ICU and hospital stays, reduces delirium, and increases muscle strength and the ability to ambulate. Long-term effects include increased ability for self-care, faster return to independent functioning, improved physical function, and reduced hospital readmission and death. Factors that influence early mobility-based rehabilitation include having an interdisciplinary team; strong unit leadership; access to physical, occupational, and respiratory therapists; a culture focused on patient safety and quality improvement; a champion of early mobility; and a focus on measuring performance and outcomes. PMID:27153308

  12. Improved understanding of aftershock triggering by waveform detection of aftershocks with GPU computing

    NASA Astrophysics Data System (ADS)

    Peng, Z.; Meng, X.; Hong, B.; Yu, X.

    2012-12-01

    Large shallow earthquakes are generally followed by increased seismic activities around the mainshock rupture zone, known as "aftershocks". Whether static or dynamic triggering is responsible for triggering aftershocks is still in debate. However, aftershocks listed in standard earthquake catalogs are generally incomplete immediately after the mainshock, which may result in inaccurate estimation of seismic rate changes. Recent studies have used waveforms of existing earthquakes as templates to scan through continuous waveforms to detect potential missing aftershocks, which is termed 'matched filter technique'. However, this kind of data mining is computationally intensive, which raises new challenges when applying to large data sets with tens of thousands of templates, hundreds of seismic stations and years of continuous waveforms. The waveform matched filter technique exhibits parallelism at multiple levels, which allows us to use GPU-based computation to achieve significant acceleration. By dividing the procedure into several routines and processing them in parallel, we have achieved ~40 times speedup for one Nvidia GPU card compared to sequential CPU code, and further scaled the code to multiple GPUs. We apply this paralleled code to detect potential missing aftershocks around the 2003 Mw 6.5 San Simeon and 2004 Mw6.0 Parkfield earthquakes in Central California, and around the 2010 Mw 7.2 El Mayor-Cucapah earthquake in southern California. In all these cases, we can detect several tens of times more earthquakes immediately after the mainshocks as compared with those listed in the catalogs. These newly identified earthquakes are revealing new information about the physical mechanisms responsible for triggering aftershocks in the near field. We plan to improve our code so that it can be executed in large-scale GPU clusters. Our work has the long-term goal of developing scalable methods for seismic data analysis in the context of "Big Data" challenges.

  13. Mississippi Curriculum Framework for Vehicle and Mobile Equipment Mechanics (Program CIP: 47.0699--Vehicle and Mobile Equipment Mech.). Secondary Programs.

    ERIC Educational Resources Information Center

    Mississippi Research and Curriculum Unit for Vocational and Technical Education, State College.

    This document, which reflects Mississippi's statutory requirement that instructional programs be based on core curricula and performance-based assessment, contains outlines of the instructional units required in local instructional management plans and daily lesson plans for vehicle and mobile equipment mechanics I and II. Presented first are a…

  14. Mobile Learning Using Mobile Phones

    ERIC Educational Resources Information Center

    Vicente, Paula

    2013-01-01

    The participation in mobile learning programs is conditioned by having/using mobile communication technology. Those who do not have or use such technology cannot participate in mobile learning programs. This study evaluates who are the most likely participants of mobile learning programs by examining the demographic profile and mobile phone usage…

  15. Houston Community College (HCC)-Mobile Go Center Program

    ERIC Educational Resources Information Center

    Ramirez, Daniel; Sterling, Cheryl; Grays, Shantay R.

    2010-01-01

    The Houston Community College Mobile Go Center brings college enrollment assistance to the doorstep of our community. It operates in a variety of settings, offering college-going material and person-to-person assistance at numerous city events. Services include assistance with academic advising, completing the FAFSA, college application process,…

  16. A Planning Study for a Cooperative State-Wide Orientation and Mobility Program for the Blind in Oregon. Project Report.

    ERIC Educational Resources Information Center

    Multnomah County Intermediate Education District, Portland, OR.

    An introduction on blindness is followed by a summary of the initial planning grant proposal for cooperative statewide orientation and mobility program for blind children. Background, development, and utilization of mobility-orientation training are discussed in conjunction with educational programs, guide dogs, canes, mobility readiness,…

  17. Early mobility and walking program for patients in intensive care units: creating a standard of care.

    PubMed

    Perme, Christiane; Chandrashekar, Rohini

    2009-05-01

    New technologies in critical care and mechanical ventilation have led to long-term survival of critically ill patients. An early mobility and walking program was developed to provide guidelines for early mobility that would assist clinicians working in intensive care units, especially clinicians working with patients who are receiving mechanical ventilation. Prolonged stays in the intensive care unit and mechanical ventilation are associated with functional decline and increased morbidity, mortality, cost of care, and length of hospital stay. Implementation of an early mobility and walking program could have a beneficial effect on all of these factors. The program encompasses progressive mobilization and walking, with the progression based on a patient's functional capability and ability to tolerate the prescribed activity. The program is divided into 4 phases. Each phase includes guidelines on positioning, therapeutic exercises, transfers, walking reeducation, and duration and frequency of mobility sessions. Additionally, the criteria for progressing to the next phase are provided. Use of this program demands a collaborative effort among members of the multidisciplinary team in order to coordinate care for and provide safe mobilization of patients in the intensive care unit.

  18. Bayesian Predictive Distribution for the Magnitude of the Largest Aftershock

    NASA Astrophysics Data System (ADS)

    Shcherbakov, R.

    2014-12-01

    Aftershock sequences, which follow large earthquakes, last hundreds of days and are characterized by well defined frequency-magnitude and spatio-temporal distributions. The largest aftershocks in a sequence constitute significant hazard and can inflict additional damage to infrastructure. Therefore, the estimation of the magnitude of possible largest aftershocks in a sequence is of high importance. In this work, we propose a statistical model based on Bayesian analysis and extreme value statistics to describe the distribution of magnitudes of the largest aftershocks in a sequence. We derive an analytical expression for a Bayesian predictive distribution function for the magnitude of the largest expected aftershock and compute the corresponding confidence intervals. We assume that the occurrence of aftershocks can be modeled, to a good approximation, by a non-homogeneous Poisson process with a temporal event rate given by the modified Omori law. We also assume that the frequency-magnitude statistics of aftershocks can be approximated by Gutenberg-Richter scaling. We apply our analysis to 19 prominent aftershock sequences, which occurred in the last 30 years, in order to compute the Bayesian predictive distributions and the corresponding confidence intervals. In the analysis, we use the information of the early aftershocks in the sequences (in the first 1, 10, and 30 days after the main shock) to estimate retrospectively the confidence intervals for the magnitude of the expected largest aftershocks. We demonstrate by analysing 19 past sequences that in many cases we are able to constrain the magnitudes of the largest aftershocks. For example, this includes the analysis of the Darfield (Christchurch) aftershock sequence. The proposed analysis can be used for the earthquake hazard assessment and forecasting associated with the occurrence of large aftershocks. The improvement in instrumental data associated with early aftershocks can greatly enhance the analysis and

  19. Early aftershock decay rate of the M6 Parkfield earthquake

    NASA Astrophysics Data System (ADS)

    Peng, Z.; Vidale, J. E.

    2004-12-01

    Mainshock rupture is typically followed by its aftershocks that diminish in rate approximately as the reciprocal of the elapse time. However, it is notoriously difficult to observe aftershock activity in the noisy aftermath of larger earthquakes. Many aftershocks were missed in the existing seismicity catalogs in the initial few minutes (Kagan, 2004). Yet this period holds valuable information about the transition from mainshock rupture to sporadic aftershocks, and the friction laws that control earthquakes. The Parkfield section of the San Andreas fault is one of most densely seismometered places in the world. Many near-fault, non-clipped and continuous recordings of the M6 Parkfield earthquake and its aftermath have been recovered, providing an excellent opportunity for us to study the aftershock decay rates in the first few hundred seconds after the mainshock. We have so far analyzed recordings from station PKD and 13 stations in the Parkfield High Resolution Seismic Network. By scrutinizing the high-frequency signal, we are able to distinguish mainshock coda from early aftershocks. We find up to 10 times more aftershocks in the first 1000 s than in the USGS NCSN catalog. More than 30 events are detected in the first 200 s after the mainshock. None of these events are in the USGS NCSN catalog. Preliminary results suggest a strong deficit of aftershocks in the first 100 s after the mainshock relative to a 1/t aftershock rate decay. This pattern is consistent with a lack of seismicity in the first 120 s following the 10/31/2001 M5.1 Anza earthquake (Kilb et al., 2004), and our study of early aftershock rates using data from HiNet array in Japan (Vidale et al., 2004). Our observations will allow us to test the prediction of such an interval in rate-and-state friction models prior to the onset of the 1/t aftershock decay rate (Dieterich, 1994).

  20. Critical thinking and clinical judgment of professional nurses in a career mobility program.

    PubMed

    Bechtel, G A; Smith, J N; Printz, V; Gronseth, D

    1993-01-01

    This study's purpose was to establish the impact of a Career Advancement Program on critical thinking and clinical judgment of Registered Nurses. Findings of the study suggest that critical thinking and clinical judgment are not influenced by patterns of upward mobility. Additionally, an analysis did not indicate significant predictors in education, specialty area, or years of nursing experience related to scores. Whereas this study questions the efficacy of career mobility programs on critical thinking and clinical judgment, it does not measure the impact of career advancement programs on other key outcome variables. The study suggests nurse educators emphasize critical thinking and clinical judgment rather than transmission of information in educational offerings.

  1. New Homes, New Neighborhoods, New Schools: A Progress Report on the Baltimore Housing Mobility Program

    ERIC Educational Resources Information Center

    Engdahl, Lora

    2009-01-01

    In the Baltimore region, a successful housing mobility program is providing families living in very disadvantaged inner city communities with a new home and a chance for a new life. Minority voucher holders in the federal Housing Choice Voucher Program (formerly titled Section 8) have often been limited to living in "voucher submarkets" where…

  2. A Fortran program for calculating electron or hole mobility in disordered semiconductors from first-principles

    NASA Astrophysics Data System (ADS)

    Li, Zi; Zhang, Xu; Lu, Gang

    2011-12-01

    A Fortran program is developed to calculate charge carrier (electron or hole) mobility in disordered semiconductors from first-principles. The method is based on non-adiabatic ab initio molecular dynamics and static master equation, treating dynamic and static disorder on the same footing. We have applied the method to calculate the hole mobility in disordered poly(3-hexylthiophene) conjugated polymers as a function of temperature and electric field and obtained excellent agreements with experimental results. The program could be used to explore structure-mobility relation in disordered semiconducting polymers/organic semiconductors and aid rational design of these materials. Program summaryProgram title: FPMu Catalogue identifier: AEJV_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJV_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 788 580 No. of bytes in distributed program, including test data, etc.: 8 433 024 Distribution format: tar.gz Programming language: Fortran 90 Computer: Any architecture with a Fortran 90 compiler Operating system: Linux, Windows RAM: Proportional to the system size, in our example, 1.2 GB Classification: 7.9 Nature of problem: Determine carrier mobility from first-principles in disordered semiconductors as a function of temperature, electric field and carrier concentration. Solution method: Iteratively solve master equation with carrier state energy and transition rates determined from first-principles. Restrictions: Mobility for disordered semiconductors where the carrier wave-functions are localized and the carrier transport is due to phonon-assisted hopping mechanism. Running time: Depending on the system size (about an hour for the example here).

  3. Local near instantaneously dynamically triggered aftershocks of large earthquakes

    NASA Astrophysics Data System (ADS)

    Fan, Wenyuan; Shearer, Peter M.

    2016-09-01

    Aftershocks are often triggered by static- and/or dynamic-stress changes caused by mainshocks. The relative importance of the two triggering mechanisms is controversial at near-to-intermediate distances. We detected and located 48 previously unidentified large early aftershocks triggered by earthquakes with magnitudes between ≥7 and 8 within a few fault lengths (approximately 300 kilometers), during times that high-amplitude surface waves arrive from the mainshock (less than 200 seconds). The observations indicate that near-to-intermediate-field dynamic triggering commonly exists and fundamentally promotes aftershock occurrence. The mainshocks and their nearby early aftershocks are located at major subduction zones and continental boundaries, and mainshocks with all types of faulting-mechanisms (normal, reverse, and strike-slip) can trigger early aftershocks.

  4. Scale-free networks of earthquakes and aftershocks.

    PubMed

    Baiesi, Marco; Paczuski, Maya

    2004-06-01

    We propose a metric to quantify correlations between earthquakes. The metric consists of a product involving the time interval and spatial distance between two events, as well as the magnitude of the first one. According to this metric, events typically are strongly correlated to only one or a few preceding ones. Thus a classification of events as foreshocks, main shocks, or aftershocks emerges automatically without imposing predetermined space-time windows. In the simplest network construction, each earthquake receives an incoming link from its most correlated predecessor. The number of aftershocks for any event, identified by its outgoing links, is found to be scale free with exponent gamma=2.0(1). The original Omori law with p=1 emerges as a robust feature of seismicity, holding up to years even for aftershock sequences initiated by intermediate magnitude events. The broad distribution of distances between earthquakes and their linked aftershocks suggests that aftershock collection with fixed space windows is not appropriate.

  5. Local near instantaneously dynamically triggered aftershocks of large earthquakes.

    PubMed

    Fan, Wenyuan; Shearer, Peter M

    2016-09-01

    Aftershocks are often triggered by static- and/or dynamic-stress changes caused by mainshocks. The relative importance of the two triggering mechanisms is controversial at near-to-intermediate distances. We detected and located 48 previously unidentified large early aftershocks triggered by earthquakes with magnitudes between ≥7 and 8 within a few fault lengths (approximately 300 kilometers), during times that high-amplitude surface waves arrive from the mainshock (less than 200 seconds). The observations indicate that near-to-intermediate-field dynamic triggering commonly exists and fundamentally promotes aftershock occurrence. The mainshocks and their nearby early aftershocks are located at major subduction zones and continental boundaries, and mainshocks with all types of faulting-mechanisms (normal, reverse, and strike-slip) can trigger early aftershocks.

  6. Local near instantaneously dynamically triggered aftershocks of large earthquakes.

    PubMed

    Fan, Wenyuan; Shearer, Peter M

    2016-09-01

    Aftershocks are often triggered by static- and/or dynamic-stress changes caused by mainshocks. The relative importance of the two triggering mechanisms is controversial at near-to-intermediate distances. We detected and located 48 previously unidentified large early aftershocks triggered by earthquakes with magnitudes between ≥7 and 8 within a few fault lengths (approximately 300 kilometers), during times that high-amplitude surface waves arrive from the mainshock (less than 200 seconds). The observations indicate that near-to-intermediate-field dynamic triggering commonly exists and fundamentally promotes aftershock occurrence. The mainshocks and their nearby early aftershocks are located at major subduction zones and continental boundaries, and mainshocks with all types of faulting-mechanisms (normal, reverse, and strike-slip) can trigger early aftershocks. PMID:27609887

  7. Childhood Lead Poisoning: Developing Prevention Programs and Mobilizing Resources.

    ERIC Educational Resources Information Center

    Rochow, K. W. James

    The current approach to dealing with childhood lead poisoning has led to repeated diagnoses of poisoning because such children are treated and then returned to their hazardous environments. This handbook describes in detail the program requirements for effective childhood lead poisoning prevention programs at the local level based on the…

  8. High-Resolution Uitra Low Power, Intergrated Aftershock and Microzonation System

    NASA Astrophysics Data System (ADS)

    Passmore, P.; Zimakov, L. G.

    2012-12-01

    Rapid Aftershock Mobilization plays an essential role in the understanding of both focal mechanism and rupture propagation caused by strong earthquakes. A quick assessment of the data provides a unique opportunity to study the dynamics of the entire earthquake process in-situ. Aftershock study also provides practical information for local authorities regarding the post earthquake activity, which is very important in order to conduct the necessary actions for public safety in the area affected by the strong earthquake. Refraction Technology, Inc. has developed a self-contained, fully integrated Aftershock System, model 160-03, providing the customer simple and quick deployment during aftershock emergency mobilization and microzonation studies. The 160-03 has no external cables or peripheral equipment for command/control and operation in the field. The 160-03 contains three major components integrated in one case: a) 24-bit resolution state-of-the art low power ADC with CPU and Lid interconnect boards; b) power source; and c) three component 2 Hz sensors (two horizontals and one vertical), and built-in ±4g accelerometer. Optionally, the 1 Hz sensors can be built-in the 160-03 system at the customer's request. The self-contained rechargeable battery pack provides power autonomy up to 7 days during data acquisition at 200 sps on continuous three weak motion and triggered three strong motion recording channels. For longer power autonomy, the 160-03 Aftershock System battery pack can be charged from an external source (solar power system). The data in the field is recorded to a built-in swappable USB flash drive. The 160-03 configuration is fixed based on a configuration file stored on the system, so no external command/control interface is required for parameter setup in the field. For visual control of the system performance in the field, the 160-03 has a built-in LED display which indicates the systems recording status as well as a hot swappable USB drive and battery

  9. Poverty, Residential Mobility, and Persistence across Urban and Rural Family Literacy Programs in Pennsylvania. Research Brief #1

    ERIC Educational Resources Information Center

    Schafft, Kai; Prins, Esther; Movit, Marcela

    2008-01-01

    This study examined how poverty and residential mobility influence low-income adults' persistence in family literacy programs in Pennsylvania. Twelve out of 20 program directors reported that learners typically moved at least once a year. In five of these high-mobility programs moving was reported to significantly hinder persistence. Geographic…

  10. Aftershocks halted by static stress shadows

    NASA Astrophysics Data System (ADS)

    Toda, Shinji; Stein, Ross S.; Beroza, Gregory C.; Marsan, David

    2012-06-01

    Earthquakes impart static and dynamic stress changes to the surrounding crust. Sudden fault slip causes small but permanent--static--stress changes, and passing seismic waves cause large, but brief and oscillatory--dynamic--stress changes. Because both static and dynamic stresses can trigger earthquakes within several rupture dimensions of a mainshock, it has proven difficult to disentangle their contributions to the triggering process. However, only dynamic stress can trigger earthquakes far from the source, and only static stress can create stress shadows, where the stress and thus the seismicity rate in the shadow area drops following an earthquake. Here we calculate the stress imparted by the magnitude 6.1 Joshua Tree and nearby magnitude 7.3 Landers earthquakes that occurred in California in April and June 1992, respectively, and measure seismicity through time. We show that, where the aftershock zone of the first earthquake was subjected to a static stress increase from the second, the seismicity rate jumped. In contrast, where the aftershock zone of the first earthquake fell under the stress shadow of the second and static stress dropped, seismicity shut down. The arrest of seismicity implies that static stress is a requisite element of spatial clustering of large earthquakes and should be a constituent of hazard assessment.

  11. Iterative Evaluation in a Mobile Counseling and Testing Program to Reach People of Color at Risk for HIV--New Strategies Improve Program Acceptability, Effectiveness, and Evaluation Capabilities

    ERIC Educational Resources Information Center

    Spielberg, Freya; Kurth, Ann; Reidy, William; McKnight, Teka; Dikobe, Wame; Wilson, Charles

    2011-01-01

    This article highlights findings from an evaluation that explored the impact of mobile versus clinic-based testing, rapid versus central-lab based testing, incentives for testing, and the use of a computer counseling program to guide counseling and automate evaluation in a mobile program reaching people of color at risk for HIV. The program's…

  12. Some facts about aftershocks to large earthquakes in California

    USGS Publications Warehouse

    Jones, Lucile M.; Reasenberg, Paul A.

    1996-01-01

    Earthquakes occur in clusters. After one earthquake happens, we usually see others at nearby (or identical) locations. To talk about this phenomenon, seismologists coined three terms foreshock , mainshock , and aftershock. In any cluster of earthquakes, the one with the largest magnitude is called the mainshock; earthquakes that occur before the mainshock are called foreshocks while those that occur after the mainshock are called aftershocks. A mainshock will be redefined as a foreshock if a subsequent event in the cluster has a larger magnitude. Aftershock sequences follow predictable patterns. That is, a sequence of aftershocks follows certain global patterns as a group, but the individual earthquakes comprising the group are random and unpredictable. This relationship between the pattern of a group and the randomness (stochastic nature) of the individuals has a close parallel in actuarial statistics. We can describe the pattern that aftershock sequences tend to follow with well-constrained equations. However, we must keep in mind that the actual aftershocks are only probabilistically described by these equations. Once the parameters in these equations have been estimated, we can determine the probability of aftershocks occurring in various space, time and magnitude ranges as described below. Clustering of earthquakes usually occurs near the location of the mainshock. The stress on the mainshock's fault changes drastically during the mainshock and that fault produces most of the aftershocks. This causes a change in the regional stress, the size of which decreases rapidly with distance from the mainshock. Sometimes the change in stress caused by the mainshock is great enough to trigger aftershocks on other, nearby faults. While there is no hard "cutoff" distance beyond which an earthquake is totally incapable of triggering an aftershock, the vast majority of aftershocks are located close to the mainshock. As a rule of thumb, we consider earthquakes to be

  13. Implications of an inverse branching aftershock sequence model.

    PubMed

    Turcotte, D L; Abaimov, S G; Dobson, I; Rundle, J B

    2009-01-01

    The branching aftershock sequence (BASS) model is a self-similar statistical model for earthquake aftershock sequences. A prescribed parent earthquake generates a first generation of daughter aftershocks. The magnitudes and times of occurrence of the daughters are obtained from statistical distributions. The first generation daughter aftershocks then become parent earthquakes that generate second generation aftershocks. The process is then extended to higher generations. The key parameter in the BASS model is the magnitude difference Deltam* between the parent earthquake and the largest expected daughter earthquake. In the application of the BASS model to aftershocks Deltam* is positive, the largest expected daughter event is smaller than the parent, and the sequence of events (aftershocks) usually dies out, but an exponential growth in the number of events with time is also possible. In this paper we explore this behavior of the BASS model as Deltam* varies, including when Deltam* is negative and the largest expected daughter event is larger than the parent. The applications of this self-similar branching process to biology and other fields are discussed.

  14. Development of a Career Ladder Mobility Program in Nursing.

    ERIC Educational Resources Information Center

    Hafer, Nylene; Davis, Steve

    This collection materials describes and illustrates various features of New Mexico Junior College's (NMJC's) career ladder program for nursing. Introductory material outlines the internal institutional factors and external influences from the nursing field that served as the basis for the development and implementation of the career ladder…

  15. Reduced Aftershock Productivity in Regions with Known Slow Slip Events

    NASA Astrophysics Data System (ADS)

    Collins, G.; Mina, A.; Richardson, E.; McGuire, J. J.

    2013-12-01

    Reduced aftershock activity has been observed in areas with high rates of aseismic slip, such as transform fault zones and some subduction zones. Fault conditions that could explain both of these observations include a low effective normal stress regime and/or a high temperature, semi-brittle/plastic rheology. To further investigate the possible connection between areas of aseismic slip and reduced aftershock productivity, we compared the mainshock-aftershock sequences in subduction zones where aseismic slip transients have been observed to those of adjacent (along-strike) regions where no slow slip events have been detected. Using the Advanced National Seismic System (ANSS) catalog, we counted aftershocks that occurred within 100 km and 14 days of 112 M>=5.0 slab earthquake mainshocks from January 1980 - July 2013, including 90 since January 2000, inside observed regions of detected slow slip: south central Alaska, Cascadia, the Nicoya Peninsula (Costa Rica), Guerrero (Mexico), and the North Island of New Zealand. We also compiled aftershock counts from 97 mainshocks from areas adjacent to each of these regions using the same criteria and over the same time interval. Preliminary analysis of these two datasets shows an aftershock triggering exponent (alpha in the ETAS model) of approximately 0.8, consistent with previous studies of aftershocks in a variety of tectonic settings. Aftershock productivity for both datasets is less than that of continental earthquakes. Contrasting the two datasets, aftershock productivity inside slow slip regions is lower than in adjacent areas along the same subduction zone and is comparable to that of mid-ocean ridge transform faults.

  16. Foreshocks and Aftershocks in Simple Earthquake Models

    NASA Astrophysics Data System (ADS)

    Tiampo, K. F.; Klein, W.; Dominguez, R.; Kazemian, J.; González, P. J.

    2014-12-01

    Natural earthquake fault systems are highly heterogeneous in space; inhomogeneities occur because the earth is made of a variety of materials of different strengths and dissipate stress differently. Because the spatial arrangement of these materials is dependent on the geologic history, the distribution of these various materials can be quite complex and occur over a wide range of length scales. Despite their inhomogeneous nature, real faults are often modeled as spatially homogeneous systems. Here we present a simple earthquake fault model based on the Olami-Feder-Christensen (OFC) and Rundle-Jackson-Brown (RJB) cellular automata models with long-range interactions that incorporates a fixed percentage of stronger sites, or 'asperity cells', into the lattice. These asperity cells are significantly stronger than the surrounding lattice sites but eventually rupture when the applied stress reaches their higher threshold stress. The introduction of these spatial heterogeneities results in temporal clustering in the model that mimics those seen in natural fault systems. We observe sequences of activity that start with a gradually accelerating number of larger events (foreshocks) prior to a mainshock that is followed by a tail of decreasing activity (aftershocks). These recurrent large events occur at regular intervals, as is often observed in historic seismicity, and the time between events and their magnitude are a function of the stress dissipation parameter. The relative length of the foreshock to aftershock sequence depends on the amount of stress dissipation in the system, resulting in relatively long aftershock sequences when the stress dissipation is large versus long foreshock sequences when the stress dissipation is weak. This work provides further evidence that the spatial and temporal patterns observed in natural seismicity are strongly influenced by the underlying physical properties and are not solely the result of a simple cascade mechanism. We find that

  17. Properties of aftershock sequences in southern California

    NASA Astrophysics Data System (ADS)

    Kisslinger, Carl; Jones, Lucile M.

    1991-07-01

    The temporal behavior of 39 aftershock sequences in southern California, 1933-1988, was modeled by the modified Omori relation. Minimum magnitudes for completeness of each sequence catalog were determined, and the maximum likelihood estimates of the parameters K, p, and c, with the standard errors on each, were determined by the Ogata algorithm. The b value of each sequence was also calculated. Many of the active faults in the region, both strike slip and thrust, were sampled. The p values were graded in terms of the size of the standard error relative to the p value itself. Most of the sequences were modeled well by the Omori relation. Many of the sequences had p values close to the mean of the whole data set, 1.11±0.25, but values significantly different from the mean, as low as 0.7 and as high as 1.8, exist. No correlation of p with either the b value of the sequence or the mainshock magnitude was found. The results suggest a direct correlation of p values is with surface heat flow, with high values in the Salton Trough (high heat flow) and one low value in the San Bernardino Mountains and on the edge of the Ventura Basin (both low heat flow). The large fraction of the sequences with p values near the mean are at locations where the heat flow is near the regional mean, 74 mW/m2. If the hypothesis that aftershock decay rate is controlled by temperature at depth is valid, the effects of other factors such as heterogeneity of the fault zone properties are superimposed on the background rate determined by temperature. Surface heat flow is taken as an indicator of crustal temperature at hypocentral depths, but the effects on heat flow of convective heat transport and variations in near-surface thermal conductivity invalidate any simple association of local variations in heat flow with details of the subsurface temperature distribution. The interpretation is that higher temperatures in the aftershock source volume caused shortened stress relaxation times in the fault

  18. VA Health Professional Scholarship and Visual Impairment and Orientation and Mobility Professional Scholarship Programs. Final rule.

    PubMed

    2013-08-20

    The Department of Veterans Affairs (VA) is amending its VA Health Professional Scholarship Program (HPSP) regulations. VA is also establishing regulations for a new program, the Visual Impairment and Orientation and Mobility Professional Scholarship Program (VIOMPSP). These regulations comply with and implement sections 302 and 603 of the Caregivers and Veterans Omnibus Health Services Act of 2010 (the 2010 Act). Section 302 of the 2010 Act established the VIOMPSP, which authorizes VA to provide financial assistance to certain students seeking a degree in visual impairment or orientation or mobility, in order to increase the supply of qualified blind rehabilitation specialists for VA and the United States. Section 603 of the 2010 Act reauthorized and modified HPSP, a program that provides scholarships for education or training in certain health care occupations.

  19. VA Health Professional Scholarship and Visual Impairment and Orientation and Mobility Professional Scholarship Programs. Final rule.

    PubMed

    2013-08-20

    The Department of Veterans Affairs (VA) is amending its VA Health Professional Scholarship Program (HPSP) regulations. VA is also establishing regulations for a new program, the Visual Impairment and Orientation and Mobility Professional Scholarship Program (VIOMPSP). These regulations comply with and implement sections 302 and 603 of the Caregivers and Veterans Omnibus Health Services Act of 2010 (the 2010 Act). Section 302 of the 2010 Act established the VIOMPSP, which authorizes VA to provide financial assistance to certain students seeking a degree in visual impairment or orientation or mobility, in order to increase the supply of qualified blind rehabilitation specialists for VA and the United States. Section 603 of the 2010 Act reauthorized and modified HPSP, a program that provides scholarships for education or training in certain health care occupations. PMID:23977714

  20. Clustering analysis of seismicity and aftershock identification.

    PubMed

    Zaliapin, Ilya; Gabrielov, Andrei; Keilis-Borok, Vladimir; Wong, Henry

    2008-07-01

    We introduce a statistical methodology for clustering analysis of seismicity in the time-space-energy domain and use it to establish the existence of two statistically distinct populations of earthquakes: clustered and nonclustered. This result can be used, in particular, for nonparametric aftershock identification. The proposed approach expands the analysis of Baiesi and Paczuski [Phys. Rev. E 69, 066106 (2004)10.1103/PhysRevE.69.066106] based on the space-time-magnitude nearest-neighbor distance eta between earthquakes. We show that for a homogeneous Poisson marked point field with exponential marks, the distance eta has the Weibull distribution, which bridges our results with classical correlation analysis for point fields. The joint 2D distribution of spatial and temporal components of eta is used to identify the clustered part of a point field. The proposed technique is applied to several seismicity models and to the observed seismicity of southern California.

  1. Correlation of foreshocks and aftershocks and asperities

    NASA Astrophysics Data System (ADS)

    Hsu, Vindell; Helsley, Charles E.; Berg, Eduard; Novelo-Casanova, David A.

    1984-11-01

    A close correlation in spatial distribution of local seismic activity and energy release patterns before and after the 1979 Petatlan, Mexico earthquake suggests heterogeneity within the fault plane of this major low-angle thrust event associated with subduction along the Middle America Trench. A simple two-asperity model is proposed to account for the complexity. Foreshocks and aftershocks of the neighboring 1981 Playa Azul earthquake showed a similar pattern. As both events occurred at the junction of the Orozco Fracture Zone and the Middle America Trench, we speculate that the observed complex fault plane is caused by subduction of the rugged ocean floor of the Orozco Fracture Zone. Short-term precursory seismicity prior to the Petatlan earthquake can be explained by using the asperity model and migration of a slip front from the south-east to the north-west across the main shock source region.

  2. Local Produce, Foreign Labor: Labor Mobility Programs and Global Trade Competitiveness in Canada

    ERIC Educational Resources Information Center

    Preibisch, Kerry L.

    2007-01-01

    Temporary visa workers are increasingly taking on a heightened profile in Canada, entering the workforce each year in greater numbers than immigrant workers with labor mobility rights (Sharma 2006). This paper examines the incorporation of foreign workers in Canadian horticulture under the Seasonal Agricultural Workers Program (SAWP). I argue that…

  3. Learner Centered Experiences with Flipped Classroom and Mobile Online Webinars in Distance Higher Education Program

    ERIC Educational Resources Information Center

    Amhag, Lisbeth

    2015-01-01

    The aim of this study is to describe and analyse students' learning activities in distance higher education program with online webinars (WEB-based semINAR) by computer, laptop or mobile app for phones and tablets directly face-to-face (F2F) with other students and teachers introduced by "flipped classroom." The data collection consists…

  4. A Physical Activity Program to Mobilize Older People: A Practical and Sustainable Approach

    ERIC Educational Resources Information Center

    Jancey, Jonine M.; Clarke, Ann; Howat, Peter A.; Lee, Andy H.; Shilton, Trevor; Fisher, John

    2008-01-01

    Purpose: Despite the documented benefits of physical activity, it remains difficult to motivate older adults to start and maintain regular physical activity. This study tested an innovative intervention for mobilizing older adults into a neighborhood-based walking program. Design and Methods: Researchers recruited a total of 260 healthy but…

  5. Technology Goes Bush: Using Mobile Technologies to Support Learning in a Bush Kinder Program

    ERIC Educational Resources Information Center

    Masters, Jennifer; Grogan, Leanne

    2015-01-01

    A "bush kinder" is the Australian equivalent of a European forest kindergarten. Although it is not usual for technology to be used in the type of program, the authors suggest that mobile technologies can be used creatively and sensitively to support learning in the bush kinder context. This paper describes an ethnographical case study…

  6. Poverty, Residential Mobility, and Persistence across Urban and Rural Family Literacy Programs in Pennsylvania

    ERIC Educational Resources Information Center

    Schafft, Kai A.; Prins, Esther S.

    2009-01-01

    This study investigates how poverty and residential mobility affect adult persistence and participation in family literacy (FL) programs. Combining data from interviews with directors and participants from a sample of FL sites in Pennsylvania, this study examines (a) the perceptions of practitioners and adult learners regarding the role of…

  7. Aftershocks triggered by fluid intrusion: Evidence for the aftershock sequence occurred 2014 in West Bohemia/Vogtland

    NASA Astrophysics Data System (ADS)

    Hainzl, S.; Fischer, T.; Čermáková, H.; Bachura, M.; Vlček, J.

    2016-04-01

    The West Bohemia/Vogtland region, central Europe, is well known for its repeating swarm activity. However, the latest activity in 2014, although spatially overlapping with previous swarm activity, consisted of three classical aftershock sequences triggered by ML3.5, 4.4, and 3.5 events. To decode the apparent system change from swarm-type to mainshock-aftershock characteristics, we have analyzed the details of the major ML4.4 sequence based on focal mechanisms and relocated earthquake data. Our analysis shows that the mainshock occurred with rotated mechanism in a step over region of the fault plane, unfavorably oriented to the regional stress field. Most of its intense aftershock activity occurred in-plane with classical characteristics such as (i) the maximum magnitude of the aftershocks is significantly less than the mainshock magnitude and (ii) the decay can be well fitted by the Omori-Utsu law. However, the absolute number of aftershocks and the fitted Omori-Utsu c and p parameters are much larger than for typical sequences. By means of the epidemic-type aftershock sequence model, we show that an additional aseismic source with an exponentially decaying strength triggered a large fraction of the aftershocks. Corresponding pore pressure simulations with an exponentially decreasing flow rate of the fluid source show a good agreement with the observed spatial migration front of the aftershocks extending approximately with log(t). Thus, we conclude that the mainshock opened fluid pathways from a finite fluid source into the fault plane explaining the unusual high rate of aftershocks, the migration patterns, and the exponential decrease of the aseismic signal.

  8. The aftershock processes of strong earthquakes in the Western Caucasus

    NASA Astrophysics Data System (ADS)

    Baranov, S. V.; Gabsatarova, I. P.

    2015-05-01

    The aftershock processes of the four strong earthquakes that occurred in the Western Caucasus from 1991 to June 2013 are considered. The main shocks of these earthquakes include the first Racha earthquake (April 29, 1991, Ms = 6.9); second Racha earthquake (June 15, 1991, Ms = 6.2); Oni earthquake (September 7, 2009, Ms = 5.8); and East Black Sea earthquake (December 23, 2012, Ms = 5.6). Based on the simulations with the LPL relaxation model and the ETAS model of triggered seismicity, the differences in the properties of the aftershock processes and the characteristics of the fault zones accommodating the main shocks are revealed. The nonrelaxation character of the aftershocks from the East Black Sea earthquake is established. It is hypothesized and validated that this is a result of the violation of the fluid-dynamic equilibrium in the fault zone due to the destruction of the gas hydrate layer by the main shock and strong aftershocks.

  9. Conceptualizing Community Mobilization for HIV Prevention: Implications for HIV Prevention Programming in the African Context

    PubMed Central

    Lippman, Sheri A.; Maman, Suzanne; MacPhail, Catherine; Twine, Rhian; Peacock, Dean; Kahn, Kathleen; Pettifor, Audrey

    2013-01-01

    Introduction Community mobilizing strategies are essential to health promotion and uptake of HIV prevention. However, there has been little conceptual work conducted to establish the core components of community mobilization, which are needed to guide HIV prevention programming and evaluation. Objectives We aimed to identify the key domains of community mobilization (CM) essential to change health outcomes or behaviors, and to determine whether these hypothesized CM domains were relevant to a rural South African setting. Method We studied social movements and community capacity, empowerment and development literatures, assessing common elements needed to operationalize HIV programs at a community level. After synthesizing these elements into six essential CM domains, we explored the salience of these CM domains qualitatively, through analysis of 10 key informant in-depth-interviews and seven focus groups in three villages in Bushbuckridge. Results CM domains include: 1) shared concerns, 2) critical consciousness, 3) organizational structures/networks, 4) leadership (individual and/or institutional), 5) collective activities/actions, and 6) social cohesion. Qualitative data indicated that the proposed domains tapped into theoretically consistent constructs comprising aspects of CM processes. Some domains, extracted from largely Western theory, required little adaptation for the South African context; others translated less effortlessly. For example, critical consciousness to collectively question and resolve community challenges functioned as expected. However, organizations/networks, while essential, operated differently than originally hypothesized - not through formal organizations, but through diffuse family networks. Conclusions To date, few community mobilizing efforts in HIV prevention have clearly defined the meaning and domains of CM prior to intervention design. We distilled six CM domains from the literature; all were pertinent to mobilization in rural

  10. Distribution of similar earthquakes in aftershocks of inland earthquakes

    NASA Astrophysics Data System (ADS)

    Hayashi, M.; Hiramatsu, Y.; Aftershock Observations Of 2007 Noto Hanto, G.

    2010-12-01

    Frictional properties control the slip behavior on a fault surface such as seismic slip and aseismic slip. Asperity, as a seismic slip area, is characterized by a strong coupling in the interseismic period and large coseismic slip. On the other hand, steady slip or afterslip occurs in an aseismic slip area around the asperity. If an afterslip area includes small asperities, a repeating rupture of single asperity can generate similar earthquakes due to the stress accumulation caused by the afterslip. We here investigate a detail distribution of similar earthquakes in the aftershocks of the 2007 Noto Hanto earthquake (Mjma 6.9) and the 2000 Western Tottori earthquake (Mjma 7.3), inland large earthquakes in Japan. We use the data obtained by the group for the aftershock observations of the 2007 Noto Hanto Earthquake and by the group for the aftershock observations of the 2000 Western Tottori earthquake. First, we select pairs of aftershocks whose cross correlation coefficients in 10 s time window of band-pass filtered waveforms of 1~4 Hz are greater than 0.95 at more than 5 stations and divide those into groups by a link of the cross correlation coefficients. Second, we reexamine the arrival times of P and S waves and the maximum amplitude for earthquakes of each group and apply the double-difference method (Waldhouser and Ellsworth, 2000) to relocate them. As a result of the analysis, we find 24 groups of similar earthquakes in the aftershocks on the source fault of the 2007 Noto Hanto Earthquake and 86 groups of similar earthquakes in the aftershocks on the source fault of the 2000 Western Tottori Earthquake. Most of them are distributed around or outside the asperity of the main shock. Geodetic studies reported that postseismic deformation was detected for the both earthquakes (Sagiya et al., 2002; Hashimoto et al., 2008). The source area of similar earthquakes seems to correspond to the afterslip area. These features suggest that the similar earthquakes observed

  11. A mechanism of aftershock generation based on progressive material softening

    NASA Astrophysics Data System (ADS)

    Dyskin, Arcady; Pasternak, Elena; Bunger, Andrew; Kear, James

    2015-04-01

    Observations of aftershocks after major seismic events show that the rate of aftershock generation reduces according to the generalised Omori's law. This law reproduces itself at a variety of scales starting from the scales of the earthquakes to the laboratory scale. Furthermore, the Omori's law holds for different types of fracture event from shear fracture propagation over the faults to failure in compression to failure in tension. In particular our tests show that the Omori's law describes the aftershocks in crystalline rocks in a laboratory model of hydraulic fracture and after bending failure of beams. We propose a new universal mechanism of aftershock generation that reproduces the Omori's law. We firstly note that it is not the residual stress, as conventionally assumed, but the residual strain that is created by the preceding fracture process. The aftershocks are created by the residual stress that is related to the residual strain through elastic moduli. The accumulation of the aftershock-related microcracks reduces the elastic moduli and thus reduces the residual stress. This overall reduction of the residual stress with the number of aftershocks is the reason for the rate reduction in aftershock generation. Naturally this process might be accompanied by the reduction in wave velocities, albeit, as we show, the reduction is rather low. The effect the accumulated microcracks have on the moduli considerably depends on the microcrack distribution over both positions and orientations. We found that (a) if the microcracks have isotropic distribution over orientations the classical Omori's law is reproduced; (b) if the microcracks are shear and parallel to each other but randomly situated in space the generalised Omori's law is reproduced with the exponent p<1; (c) if the microcracks are represented by sliding zones distributed over a fault, the generalised Omori's law is reproduced with the exponent p>1. The main feature of the latter case is the existence of

  12. A Variety of Aftershock Decays in the Rate- and State-Friction Model Due to the Effect of Secondary Aftershocks: Implications Derived from an Analysis of Real Aftershock Sequences

    NASA Astrophysics Data System (ADS)

    Iwata, Takaki

    2016-01-01

    The model based on rate- and state-dependent friction law reproduces the temporal decay of an aftershock sequence with the p value of the Omori-Utsu law equal to 1, if we simply assume a constant stress rate over time. However, because p values vary in real aftershock sequences, this model requires some modification. This study examined the effect of secondary aftershocks on the variety of the p value. A large aftershock causes a stepwise stress increase in the aftershock area, and the expected seismicity rate derived from the friction law also increases abruptly. These multiple increases in the seismicity rate during its decay following a mainshock could cause variation in the apparent p value. In this study, a model incorporating this idea is applied to two aftershock sequences observed in Japan and is shown to substantially modify the modeling of aftershock activity.

  13. Preferred listening levels of mobile phone programs when considering subway interior noise

    PubMed Central

    Yu, Jyaehyoung; Lee, Donguk; Han, Woojae

    2016-01-01

    Today, people listen to music loud using personal listening devices. Although a majority of studies have reported that the high volume played on these listening devices produces a latent risk of hearing problems, there is a lack of studies on “double noise exposures” such as environmental noise plus recreational noise. The present study measures the preferred listening levels of a mobile phone program with subway interior noise for 74 normal-hearing participants in five age groups (ranging from 20s to 60s). The speakers presented the subway interior noise at 73.45 dB, while each subject listened to three application programs [Digital Multimedia Broadcasting (DMB), music, game] for 30 min using a tablet personal computer with an earphone. The participants’ earphone volume levels were analyzed using a sound level meter and a 2cc coupler. Overall, the results showed that those in their 20s listened to the three programs significantly louder with DMB set at significantly higher volume levels than for the other programs. Higher volume levels were needed for middle frequency compared to the lower and higher frequencies. We concluded that any potential risk of noise-induced hearing loss for mobile phone users should be communicated when users listen regularly, although the volume level was not high enough that the users felt uncomfortable. When considering individual listening habits on mobile phones, further study to predict total accumulated environmental noise is still needed. PMID:26780960

  14. Preferred listening levels of mobile phone programs when considering subway interior noise.

    PubMed

    Yu, Jyaehyoung; Lee, Donguk; Han, Woojae

    2016-01-01

    Today, people listen to music loud using personal listening devices. Although a majority of studies have reported that the high volume played on these listening devices produces a latent risk of hearing problems, there is a lack of studies on "double noise exposures" such as environmental noise plus recreational noise. The present study measures the preferred listening levels of a mobile phone program with subway interior noise for 74 normal-hearing participants in five age groups (ranging from 20s to 60s). The speakers presented the subway interior noise at 73.45 dB, while each subject listened to three application programs [Digital Multimedia Broadcasting (DMB), music, game] for 30 min using a tablet personal computer with an earphone. The participants' earphone volume levels were analyzed using a sound level meter and a 2cc coupler. Overall, the results showed that those in their 20s listened to the three programs significantly louder with DMB set at significantly higher volume levels than for the other programs. Higher volume levels were needed for middle frequency compared to the lower and higher frequencies. We concluded that any potential risk of noise-induced hearing loss for mobile phone users should be communicated when users listen regularly, although the volume level was not high enough that the users felt uncomfortable. When considering individual listening habits on mobile phones, further study to predict total accumulated environmental noise is still needed. PMID:26780960

  15. On the adaptive daily forecasting of seismic aftershock hazard

    NASA Astrophysics Data System (ADS)

    Ebrahimian, Hossein; Jalayer, Fatemeh; Asprone, Domenico; Lombardi, Anna Maria; Marzocchi, Warner; Prota, Andrea; Manfredi, Gaetano

    2013-04-01

    Post-earthquake ground motion hazard assessment is a fundamental initial step towards time-dependent seismic risk assessment for buildings in a post main-shock environment. Therefore, operative forecasting of seismic aftershock hazard forms a viable support basis for decision-making regarding search and rescue, inspection, repair, and re-occupation in a post main-shock environment. Arguably, an adaptive procedure for integrating the aftershock occurrence rate together with suitable ground motion prediction relations is key to Probabilistic Seismic Aftershock Hazard Assessment (PSAHA). In the short-term, the seismic hazard may vary significantly (Jordan et al., 2011), particularly after the occurrence of a high magnitude earthquake. Hence, PSAHA requires a reliable model that is able to track the time evolution of the earthquake occurrence rates together with suitable ground motion prediction relations. This work focuses on providing adaptive daily forecasts of the mean daily rate of exceeding various spectral acceleration values (the aftershock hazard). Two well-established earthquake occurrence models suitable for daily seismicity forecasts associated with the evolution of an aftershock sequence, namely, the modified Omori's aftershock model and the Epidemic Type Aftershock Sequence (ETAS) are adopted. The parameters of the modified Omori model are updated on a daily basis using Bayesian updating and based on the data provided by the ongoing aftershock sequence based on the methodology originally proposed by Jalayer et al. (2011). The Bayesian updating is used also to provide sequence-based parameter estimates for a given ground motion prediction model, i.e. the aftershock events in an ongoing sequence are exploited in order to update in an adaptive manner the parameters of an existing ground motion prediction model. As a numerical example, the mean daily rates of exceeding specific spectral acceleration values are estimated adaptively for the L'Aquila 2009

  16. Foreshock and Aftershocks in Simple Earthquake Models

    NASA Astrophysics Data System (ADS)

    Kazemian, J.; Tiampo, K. F.; Klein, W.; Dominguez, R.

    2015-02-01

    Many models of earthquake faults have been introduced that connect Gutenberg-Richter (GR) scaling to triggering processes. However, natural earthquake fault systems are composed of a variety of different geometries and materials and the associated heterogeneity in physical properties can cause a variety of spatial and temporal behaviors. This raises the question of how the triggering process and the structure interact to produce the observed phenomena. Here we present a simple earthquake fault model based on the Olami-Feder-Christensen and Rundle-Jackson-Brown cellular automata models with long-range interactions that incorporates a fixed percentage of stronger sites, or asperity cells, into the lattice. These asperity cells are significantly stronger than the surrounding lattice sites but eventually rupture when the applied stress reaches their higher threshold stress. The introduction of these spatial heterogeneities results in temporal clustering in the model that mimics that seen in natural fault systems along with GR scaling. In addition, we observe sequences of activity that start with a gradually accelerating number of larger events (foreshocks) prior to a main shock that is followed by a tail of decreasing activity (aftershocks). This work provides further evidence that the spatial and temporal patterns observed in natural seismicity are strongly influenced by the underlying physical properties and are not solely the result of a simple cascade mechanism.

  17. Foreshocks and aftershocks of the Great 1857 California earthquake

    USGS Publications Warehouse

    Meltzner, A.J.; Wald, D.J.

    1999-01-01

    The San Andreas fault is the longest fault in California and one of the longest strike-slip faults anywhere in the world, yet we know little about many aspects of its behavior before, during, and after large earthquakes. We conducted a study to locate and to estimate magnitudes for the largest foreshocks and aftershocks of the 1857 M 7.9 Fort Tejon earthquake on the central and southern segments of the fault. We began by searching archived first-hand accounts from 1857 through 1862, by grouping felt reports temporally, and by assigning modified Mercalli intensities to each site. We then used a modified form of the grid-search algorithm of Bakum and Wentworth, derived from empirical analysis of modern earthquakes, to find the location and magnitude most consistent with the assigned intensities for each of the largest events. The result confirms a conclusion of Sieh that at least two foreshocks ('dawn' and 'sunrise') located on or near the Parkfield segment of the San Andreas fault preceded the mainshock. We estimate their magnitudes to be M ~ 6.1 and M ~ 5.6, respectively. The aftershock rate was below average but within one standard deviation of the number of aftershocks expected based on statistics of modern southern California mainshock-aftershock sequences. The aftershocks included two significant events during the first eight days of the sequence, with magnitudes M ~ 6.25 and M ~ 6.7, near the southern half of the rupture; later aftershocks included a M ~ 6 event near San Bernardino in December 1858 and a M ~ 6.3 event near the Parkfield segment in April 1860. From earthquake logs at Fort Tejon, we conclude that the aftershock sequence lasted a minimum of 3.75 years.

  18. LOFT. Mobile test building (TAN624) is recycled from ANP program ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    LOFT. Mobile test building (TAN-624) is recycled from ANP program for placement before LOFT containment building door. It has not yet been connected to containment building. Note borated water tank at right of dome. Narrow, vertical structure at right of door is shroud is shroud for air exhaust duct. Filter vaults lie between duct shroud and stack. Camera facing westerly. Date: 1974. INEEL negative no. 74-1072 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

  19. Interpretive Flexibility in Mobile Health: Lessons From a Government-Sponsored Home Care Program

    PubMed Central

    Mathiassen, Lars

    2013-01-01

    Background Mobile technologies have emerged as important tools that health care personnel can use to gain easy access to client data anywhere. This is particularly useful for nurses and care workers in home health care as they provide services to clients in many different settings. Although a growing body of evidence supports the use of mobile technologies, the diverse implications of mobile health have yet to be fully documented. Objective Our objective was to examine a large-scale government-sponsored mobile health implementation program in the Danish home care sector and to understand how the technology was used differently across home care agencies. Methods We chose to perform a longitudinal case study with embedded units of analysis. We included multiple data sources, such as written materials, a survey to managers across all 98 Danish municipalities, and semistructured interviews with managers, care workers, and nurses in three selected home care agencies. We used process models of change to help analyze the overall implementation process from a longitudinal perspective and to identify antecedent conditions, key events, and practical outcomes. Results Strong collaboration between major stakeholders in the Danish home care sector (government bodies, vendors, consultants, interest organizations, and managers) helped initiate and energize the change process, and government funding supported quick and widespread technology adoption. However, although supported by the same government-sponsored program, mobile technology proved to have considerable interpretive flexibility with variation in perceived nature of technology, technology strategy, and technology use between agencies. What was first seen as a very promising innovation across the Danish home care sector subsequently became the topic of debate as technology use arrangements ran counter to existing norms and values in individual agencies. Conclusions Government-sponsored programs can have both positive and

  20. Creating Mobile and Web Application Programming Interfaces (APIs) for NASA Science Data

    NASA Astrophysics Data System (ADS)

    Oostra, D.; Chambers, L. H.; Lewis, P. M.; Moore, S. W.

    2011-12-01

    The Atmospheric Science Data Center (ASDC) at the NASA Langley Research Center in Virginia houses almost three petabytes of data, a collection that increases every day. To put it into perspective, it is estimated that three petabytes of data storage could store a digitized copy of all printed material in U.S. research libraries. There are more than ten other NASA data centers like the ASDC. Scientists and the public use this data for research, science education, and to understand our environment. Most importantly these data provide the potential for all of us make new discoveries. NASA is about making discoveries. Galileo was quoted as saying, "All discoveries are easy to understand once they are discovered. The point is to discover them." To that end, NASA stores vast amounts of publicly available data. This paper examines an approach to create web applications that serve NASA data in ways that specifically address the mobile web application technologies that are quickly emerging. Mobile data is not a new concept. What is new, is that user driven tools have recently become available that allow users to create their own mobile applications. Through the use of these cloud-based tools users can produce complete native mobile applications. Thus, mobile apps can now be created by everyone, regardless of their programming experience or expertise. This work will explore standards and methods for creating dynamic and malleable application programming interfaces (APIs) that allow users to access and use NASA science data for their own needs. The focus will be on experiences that broaden and increase the scope and usage of NASA science data sets.

  1. Aftershocks Following the 9 April 2013 Bushehr Earthquake, Iran

    PubMed Central

    Ardalan, Ali; Hajiuni, Alireza; Zare, Mehdi

    2013-01-01

    On 9 April 2013 at 11:52 UTC (16:22 local time), a Mw 6.2 earthquake occurred at the depth of 20 Km in Dashti district in south-west Iran’s Bushehr province. The macroseismic epicenter was located nearby the city of Shonbeh. During one month after the earthquake, a total of 282 aftershocks hit the epicentral region, mostly at the east and north sides. They ranged from 2.5 to 5.7 on the Richter scale. Seventy aftershocks (24.9%) were M4.0-4.9 and eight (2.8%) were M5.0-5.7. Aftershocks are potentially able to do additional damage. In Bushehr earthquake, a M5.4 aftershock on 10 April in Chahgah village caused at least four injuries and destruction of several buildings that had been already damaged by the main shock. Knowledge about the aftershock induced damages provides opportunities for timely risk communication with the affected people and for long term community education. This will hopefully increase the community awareness and minimize the risk of further loss of lives. PMID:24042232

  2. Aftershocks following the 9 april 2013 bushehr earthquake, iran.

    PubMed

    Ardalan, Ali; Hajiuni, Alireza; Zare, Mehdi

    2013-08-28

    On 9 April 2013 at 11:52 UTC (16:22 local time), a Mw 6.2 earthquake occurred at the depth of 20 Km in Dashti district in south-west Iran's Bushehr province. The macroseismic epicenter was located nearby the city of Shonbeh. During one month after the earthquake, a total of 282 aftershocks hit the epicentral region, mostly at the east and north sides. They ranged from 2.5 to 5.7 on the Richter scale. Seventy aftershocks (24.9%) were M4.0-4.9 and eight (2.8%) were M5.0-5.7. Aftershocks are potentially able to do additional damage. In Bushehr earthquake, a M5.4 aftershock on 10 April in Chahgah village caused at least four injuries and destruction of several buildings that had been already damaged by the main shock. Knowledge about the aftershock induced damages provides opportunities for timely risk communication with the affected people and for long term community education. This will hopefully increase the community awareness and minimize the risk of further loss of lives.

  3. Curricular and Extra-Curricular Programs Supporting Improved International Learning Mobility Experiences: An Emerging Trend in Australia

    ERIC Educational Resources Information Center

    Molony, John

    2011-01-01

    International learning mobility is a strategic and operational priority for both the federal government and the majority of universities in Australia. Dating back over a decade, successive governments have stressed the public good to be derived from having an increased proportion of students participating in mobility programs. It is seen as…

  4. Improvement of air quality according to Mobile reduction measures to establish Korean Auto-oil program

    NASA Astrophysics Data System (ADS)

    Sunwoo, Y.; Jo, H.; Ma, Y.; Kim, S.; Hong, K.; Lim, Y.; Javascript:Setnextpage('sponsor')

    2011-12-01

    The mobile of NOx and PM10 emission of Korea in 2007 accounted for 42%, 23%, respectively (excluded fugitive dust). Seoul highly affected mobile emission which accounted for 46%, 49%, respectively. Korean government ,therefore, established "Special Act for improvement of air quality in Seoul metropolitan area" including mobile emission reduction measures and organized research forum including reformation of fuel and cars, risk assessment, control of greenhouse gas and assessment of air quality to establish Korean Auto-oil program This study quantitatively analyses improvement of air quality in Seoul according to the reformation of fuel and supply of DPF in Korean Auto-oil program. WRF-SMOKE-CMAQ were emploied for this study. SO2, CO, NOx, PM10 and VOCs emission are based on the INTEX-B emission inventory, NH3 were from the REAS emission inventory. Korea emission is derived by CAPSS (Clean Air Policy Support System) data. The reduction through reformation of fuel and supply of DPF is calculated by reduction ratio of air pollutants with strengthen fuel quality standard and number of car supplied DPF, refer to Metropolitan Air Quality Management Office Republic of Korea (2011) in detail. The effect of air quality is quantifiably comparing modeling results which are applied/not applied on the measures. This study will be provided basic data to establish Korean Auto-oil program through quantifying and predicting to improvement of air quality according to the mobile measures. Acknowledgement This research was supported in part by the "Assessment of risk and health benefits considering exposure characteristics of fuel" project sponsored by the Korea Automobile Environmental Association.

  5. Comparison of the non-proliferation event aftershocks with other Nevada Test Site events

    SciTech Connect

    Jarpe, S.; Goldstein, P.; Zucca, J.J.

    1994-04-01

    As part of a larger effort to develop technology for on-site inspection of ambiguous underground seismic events, we have been working to identify phenomenology of aftershock seismicity which would be useful for discriminating between nuclear explosions, chemical explosions, earthquakes or other seismic events. Phenomenology we have investigated includes; the spatial distribution of aftershocks, the number of aftershocks as a function of time after the main event, the size of the aftershocks, and waveform frequency content. Our major conclusions are: (1) Depending on local geologic conditions, aftershock production rate two weeks after zero time ranges from 1 to 100 per day. (2) Aftershocks of concentrated chemical explosions such as the NPE are indistinguishable from aftershocks of nuclear explosions. (3) Earthquake and explosion aftershock sequences may be differentiated on the basis of depth, magnitude, and in some cases, frequency content of seismic signals.

  6. Aftershock activity of the 2015 Gorkha, Nepal, earthquake determined using the Kathmandu strong motion seismographic array

    NASA Astrophysics Data System (ADS)

    Ichiyanagi, Masayoshi; Takai, Nobuo; Shigefuji, Michiko; Bijukchhen, Subeg; Sasatani, Tsutomu; Rajaure, Sudhir; Dhital, Megh Raj; Takahashi, Hiroaki

    2016-02-01

    The characteristics of aftershock activity of the 2015 Gorkha, Nepal, earthquake (Mw 7.8) were evaluated. The mainshock and aftershocks were recorded continuously by the international Kathmandu strong motion seismographic array operated by Hokkaido University and Tribhuvan University. Full waveform data without saturation for all events enabled us to clarify aftershock locations and decay characteristics. The aftershock distribution was determined using the estimated local velocity structure. The hypocenter distribution in the Kathmandu metropolitan region was well determined and indicated earthquakes located shallower than 12 km depth, suggesting that aftershocks occurred at depths shallower than the Himalayan main thrust fault. Although numerical investigation suggested less resolution for the depth component, the regional aftershock epicentral distribution of the entire focal region clearly indicated earthquakes concentrated in the eastern margin of the major slip region of the mainshock. The calculated modified Omori law's p value of 1.35 suggests rapid aftershock decay and a possible high temperature structure in the aftershock region.

  7. Constant connections: piloting a mobile phone-based peer support program for Nuer (southern Sudanese) women.

    PubMed

    Wollersheim, Dennis; Koh, Lee; Walker, Rae; Liamputtong, Pranee

    2013-01-01

    Refugee women have poor psychosocial health as a result of past trauma and difficulties associated with settlement. This study was a pilot to find out how to use mobile phone-based peer support to improve the psychosocial health of, and facilitate settlement in a group of nine Nuer refugee women in Melbourne, Australia. Nine participants recruited by a community leader received peer support training over two five-week periods. They were further provided with mobile phone recharge vouchers to call one another to practice peer support techniques. The fifth and final sessions were focus groups to evaluate the intervention. Notes from the focus groups were thematically analysed. The women reported greater confidence and empowerment as they received more support, had better connections within the group and better access to information. Relationships with friends, family and the community became richer as they adopted and experienced more functional communication patterns. Using mobile phones for peer support helped to re-create community by bridging the geographical distance that separates refugee women. It allowed the women, from similar backgrounds and with similar experiences, to provide mutual support and exchange information through a verbal channel, the form of communication they are most comfortable with. The program demonstrates the positive psychosocial effect of peer support in a refugee community, and provides a viable model for using mobile phones in health promotion interventions. The successful outcomes, as perceived by the participants, are indicative of the potential of using technology to bridge health inequities in a marginalised group.

  8. Weight loss efficacy of a novel mobile Diabetes Prevention Program delivery platform with human coaching

    PubMed Central

    Michaelides, Andreas; Raby, Christine; Wood, Meghan; Farr, Kit

    2016-01-01

    Objective To evaluate the weight loss efficacy of a novel mobile platform delivering the Diabetes Prevention Program. Research Design and Methods 43 overweight or obese adult participants with a diagnosis of prediabetes signed-up to receive a 24-week virtual Diabetes Prevention Program with human coaching, through a mobile platform. Weight loss and engagement were the main outcomes, evaluated by repeated measures analysis of variance, backward regression, and mediation regression. Results Weight loss at 16 and 24 weeks was significant, with 56% of starters and 64% of completers losing over 5% body weight. Mean weight loss at 24 weeks was 6.58% in starters and 7.5% in completers. Participants were highly engaged, with 84% of the sample completing 9 lessons or more. In-app actions related to self-monitoring significantly predicted weight loss. Conclusions Our findings support the effectiveness of a uniquely mobile prediabetes intervention, producing weight loss comparable to studies with high engagement, with potential for scalable population health management.

  9. Weight loss efficacy of a novel mobile Diabetes Prevention Program delivery platform with human coaching

    PubMed Central

    Michaelides, Andreas; Raby, Christine; Wood, Meghan; Farr, Kit

    2016-01-01

    Objective To evaluate the weight loss efficacy of a novel mobile platform delivering the Diabetes Prevention Program. Research Design and Methods 43 overweight or obese adult participants with a diagnosis of prediabetes signed-up to receive a 24-week virtual Diabetes Prevention Program with human coaching, through a mobile platform. Weight loss and engagement were the main outcomes, evaluated by repeated measures analysis of variance, backward regression, and mediation regression. Results Weight loss at 16 and 24 weeks was significant, with 56% of starters and 64% of completers losing over 5% body weight. Mean weight loss at 24 weeks was 6.58% in starters and 7.5% in completers. Participants were highly engaged, with 84% of the sample completing 9 lessons or more. In-app actions related to self-monitoring significantly predicted weight loss. Conclusions Our findings support the effectiveness of a uniquely mobile prediabetes intervention, producing weight loss comparable to studies with high engagement, with potential for scalable population health management. PMID:27651911

  10. Aftershocks and triggered events of the Great 1906 California earthquake

    USGS Publications Warehouse

    Meltzner, A.J.; Wald, D.J.

    2003-01-01

    The San Andreas fault is the longest fault in California and one of the longest strike-slip faults in the world, yet little is known about the aftershocks following the most recent great event on the San Andreas, the Mw 7.8 San Francisco earthquake on 18 April 1906. We conducted a study to locate and to estimate magnitudes for the largest aftershocks and triggered events of this earthquake. We examined existing catalogs and historical documents for the period April 1906 to December 1907, compiling data on the first 20 months of the aftershock sequence. We grouped felt reports temporally and assigned modified Mercalli intensities for the larger events based on the descriptions judged to be the most reliable. For onshore and near-shore events, a grid-search algorithm (derived from empirical analysis of modern earthquakes) was used to find the epicentral location and magnitude most consistent with the assigned intensities. For one event identified as far offshore, the event's intensity distribution was compared with those of modern events, in order to contrain the event's location and magnitude. The largest aftershock within the study period, an M ???6.7 event, occurred ???100 km west of Eureka on 23 April 1906. Although not within our study period, another M ???6.7 aftershock occurred near Cape Mendocino on 28 October 1909. Other significant aftershocks included an M ???5.6 event near San Juan Bautista on 17 May 1906 and an M ???6.3 event near Shelter Cove on 11 August 1907. An M ???4.9 aftershock occurred on the creeping segment of the San Andreas fault (southeast of the mainshock rupture) on 6 July 1906. The 1906 San Francisco earthquake also triggered events in southern California (including separate events in or near the Imperial Valley, the Pomona Valley, and Santa Monica Bay), in western Nevada, in southern central Oregon, and in western Arizona, all within 2 days of the mainshock. Of these trigerred events, the largest were an M ???6.1 earthquake near Brawley

  11. Effectiveness of multicomponent programs with community mobilization for reducing alcohol-impaired driving.

    PubMed

    Shults, Ruth A; Elder, Randy W; Nichols, James L; Sleet, David A; Compton, Richard; Chattopadhyay, Sajal K

    2009-10-01

    A systematic review was conducted to determine the effectiveness and economic efficiency of multicomponent programs with community mobilization for reducing alcohol-impaired driving. The review was conducted for the Guide to Community Preventive Services (Community Guide). Six studies of programs qualified for the review. Programs addressed a wide range of alcohol-related concerns in addition to alcohol-impaired driving. The programs used various crash-related outcomes to measure their effectiveness. Two studies examined fatal crashes and reported declines of 9% and 42%; one study examined injury crashes and reported a decline of 10%; another study examined crashes among young drivers aged 16-20 years and reported a decline of 45%; and one study examined single-vehicle late-night and weekend crashes among young male drivers and reported no change. The sixth study examined injury crashes among underage drivers and reported small net reductions. Because the actual numbers of crashes were not reported, percentage change could not be calculated. According to Community Guide rules of evidence, the studies reviewed here provided strong evidence that carefully planned, well-executed multicomponent programs, when implemented in conjunction with community mobilization efforts, are effective in reducing alcohol-related crashes. Three studies reported economic evidence that suggests that such programs produce cost savings. The multicomponent programs generally included a combination of efforts to limit access to alcohol (particularly among youth), responsible beverage service training, sobriety checkpoints or other well-defined enforcement efforts, public education, and media advocacy designed to gain the support of both policymakers and the general public for reducing alcohol-impaired driving.

  12. Source Characteristics of Aftershocks of the India Republic Day Earthquake

    NASA Astrophysics Data System (ADS)

    Horton, S.; Bodin, P.; Johnston, A.; Withers, M.; Chiu, C.; Raphael, A.; Rabak, I.; Maio, Q.; Smalley, R.; Chiu, J.; Langston, C.

    2001-05-01

    We present a preliminary analysis of aftershocks of the Mw=7.7 Republic Day (26 January) 2001 earthquake in Gujarat, India, recorded on a network of portable digital event recorders (the MAEC/ISTAR network). During the 18 day deployment, this network recorded ground motion from nearly 2000 earthquakes; almost exclusively M<5 events within about 100 km of all stations. In this talk we will discuss the results of an analysis of approximately 400 earthquakes that were recorded at 6 or more sites. Because of its history of infrequent moderate-to-large earthquakes and its setting within a continental plate interior (albeit rather close to a rather diffuse continental boundary), studies of the Kachchh region may provide important insights for other high-consequence-but-low-occurrence-rate regions, such as the central US. A series of unfortunate circumstances has cast an obscuring veil of ignorance over the mainshock: we know of no strong-motion recordings of the mainshock, regional broad-band and seismic network data is notoriously difficult to obtain for scientific evaluation, evidence of surface rupture or deformation is fragmentary and complex or obscured by massive liquefaction, pre-existing geodetic networks are non-existent, and satellite-based radar interferometry studies have been hobbled by poor pre-earthquake images. Aftershock occurrence may provide critical evidence to determine which fault ruptured in January, 2001, and aftershock studies may provide important observational constraints on source processes and wave propagation in the region. We focus on trying to discern the mainshock fault plane, which appears to dip to the south, and whether the aftershocks are unusually deep (down to 35 km, which might help to explain the lack of obvious surface rupture). In addition to determining first-motion focal mechanisms we will examine whether stress drops of the aftershocks are, on the whole, high. We compare the seismic sources and regional propagation of

  13. Statistical signatures of aftershock sequences generated by supershear mainshocks

    NASA Astrophysics Data System (ADS)

    Bhattacharya, P.; Shcherbakov, R.; Tiampo, K. F.; Mansinha, L.

    2010-12-01

    The rupture process during supershear earthquakes generates a seismic shock wave redistributing stress away from the fault resembling a sonic boom produced by a supersonic aircraft. This leads to a relative quiescence in aftershock activity along the supershear segment of the rupture. The occurrence of supershear ruptures is also generally associated with a region of local high pre-stress and an unusually smooth friction profile over the supershear segment, leading to a conspicuous absence of high frequency ground motions. We have considered the aftershock sequences of five well-known supershear earthquakes from around the world (1979 Imperial Valley, 1992 Landers, 1999 Izmit and Duzce and 2002 Denali earthquakes) to test whether the aftershock statistics around the supershear rupture are different from the statistics in the rest of the region due to the aforementioned stress conditions and redistributions. Specifically, we have looked at the frequency-magnitude distribution in order to study the variation of the b value for each of the sequences and observe statistically significant variations. In particular, we have determined that the b value is always higher in the zone surrounding a supershear segment than in the rest of the aftershock region. The Omori Law, however, does not show such clear trends. We also looked at the average difference in magnitude between the mainshock and the largest aftershock and found it is larger than that predicted by Bath's law. The results certainly point towards a relationship between aftershock statistics and the mainshock rupture process and might facilitate a physical process based understanding of the empirical laws of earthquake statistics.

  14. Seismic moment ratio of aftershocks with respect to main shocks

    NASA Astrophysics Data System (ADS)

    Zakharova, O.; Hainzl, S.; Bach, C.

    2013-11-01

    The empirical Båth's law indicates that the earthquake process is self-similar and provides an opportunity to estimate the magnitude of the largest aftershock subsequent to a main shock. However, the analysis of this relation is limited to a small magnitude range and also depends on the aftershock selection rules. As an alternative, we analyze, in this paper, the cumulative seismic moment of aftershocks relative to the main shock moment, because (i) it is a physical quantity that does not only take the largest aftershock into account; (ii) background activity can be considered and as a result estimations are less affected by selection rules; and (iii) the effects of the catalog cut-off magnitude can be corrected, what leads to larger magnitude range for the analysis. We analyze the global preliminary determination of epicenters U.S. Geological Society catalog (combined with centroid moment tensor focal mechanisms) and find that the seismic moment release of aftershocks is on average approximately 5% of the main shock seismic moment. We show that the results can be well fitted by simulations of the Epidemic Type Aftershock Sequence model. In particular, we test whether simulations constrained by predictions of the static stress-triggering model, proposing a break of self-similarity due to the finite seismogenic width, are in agreement with observations. Our analysis shows that the observed dependency on the main shock magnitude as well as systematic variations with the main shock fault plane solution can be both explained by the constraints based on the static stress triggering.

  15. Simulating Aftershocks for an On Site Inspection (OSI) Exercise

    SciTech Connect

    Sweeney, J. J.; Ford, S. R.

    2015-10-05

    The experience of IFE14 emphasizes the need for a better way to simulate aftershocks during an OSI exercise. The obvious approach is to develop a digital model of aftershocks that can be used either for a real field exercise or for a computer simulation that can be done in an office, for training for example. However, this approach involves consideration of several aspects, such as how and when to introduce waveforms in a way that maximizes the realism of the data and that will be convincing to a savvy, experienced seismic analyst. The purpose of this report is to outline a plan for how this approach can be implemented.

  16. Aftershock Number for Forecasting Short-Term Earthquake Probabilities

    NASA Astrophysics Data System (ADS)

    Christophersen, A.; Smith, E. G.

    2004-12-01

    Data from earthquakes worldwide with depths shallower than 70 km were combined from the International Seismological Centre, the US National Earthquake Information Center, Blacknest, and Harvard. An extensive magnitude and catalogue completeness study defined a `best' magnitude using the Harvard moment as a reference. The catalogue covers the period 1964 to 1995 and is effectively complete for earthquakes of magnitude 5.0 and above. The data were divided into six tectonic settings, and searched for related events using a simple window in space and time. An objective method was developed to define an elliptical aftershock area. The database of aftershock sequences has about 28,000 mainshocks of which about 2,400 have a magnitude M ≥ 6.0, and these were followed by a total of about 7,000 aftershocks. The database was analyzed in space, time, magnitude, and in the number of aftershocks in a sequence, hereafter called abundance. The aftershock decay in time and the magnitude-frequency distribution follow well- established empirical laws, Omori's law and the Gutenberg and Richter relationship. These relationships were analyzed by stacking data from various sequences within the same tectonic setting. The p-value for the aftershock decay in time was found to be 1.0 for subduction and collision zones, and for regions of mixed tectonic character like New Zealand. For mid-ocean ridges the p-value of the present dataset is 1.19 ± 0.08 and for intracontinental zones 0.86 ± 0.14. The b-value of the magnitude-frequency relation is 1.0 for aftershock sequences in all settings. No variation of the b-value with time was observed. The abundance varies greatly from sequence to sequence. It can be modeled by a geometric distribution, where the mean abundance N grows exponentially with mainshock magnitude, M i.e. log N is proportional to M. The distribution parameters for time, magnitude and abundance can be combined to probabilistically predict the number of aftershocks in a given

  17. Nonlinear Viscoelastic Stress Transfer As a Possible Aftershock Triggering Mechanism

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Shcherbakov, R.

    2014-12-01

    The earthquake dynamics can be modelled by employing the spring-block system [Burridge and Knopoff, 1967]. In this approach the earthquake fault is modelled by an array of blocks coupling the loading plate and the lower plate. The dynamics of the system is governed by the system of equations of motion for each block. It is possible to map this system into a cellular automata model, where the stress acting on each block is increased in each time step, and the failing process (frictional slip) is described by stress transfer rules [Olami et al, 1992]. The OFC model produces a power-law distribution for avalanche statistics but it is not capable of producing robust aftershock sequences which follow Omori's law.We propose a nonlinear viscoelastic stress transfer mechanism in the aftershock triggering. In a basic spring-block model setting, we introduce the nonlinear viscoelastic stress transfer between neighbouring blocks, as well as between blocks and the top loading plate. The shear stress of the viscous component is a power-law function of the velocity gradient with an exponent smaller or greater than 1 for the nonlinear viscoelasticity, or 1 for the linear case. The stress transfer function of this nonlinear viscoelastic model has a power-law time-dependent form. It features an instantaneous stress transmission triggering an instantaneous avalanche, which is the same as the original spring-block model; and a power-law relaxation term, which could trigger further aftershocks. We incorporate this nonlinear viscoelasticity mechanism in a lattice cellular automata model. The model could exhibit both the Gutenberg-Richter scaling for the frequency-magnitude distribution and a power-law time decay of aftershocks, which is in accordance with Omori's law. Our study suggests that the stress transfer function may play an important role in the aftershock triggering. We have found that the time decay curve of aftershocks is affected by the shape of the stress transfer function

  18. Spatial Distributions of Foreshocks and Aftershocks: Static or Dynamic Triggering

    NASA Astrophysics Data System (ADS)

    Werner, M. J.; Rubin, A. M.

    2012-04-01

    In recent years, the spatial distributions of foreshocks and aftershocks have been scrutinized for evidence supporting either triggering by static stress changes induced by the permanent deformation from prior earthquakes or triggering by the dynamic stresses from seismic waves. Felzer & Brodsky (2006) identified small (m<4) mainshocks and triggered aftershocks, stacked the distances between these pairs and observed a single power-law decay with distance that extends beyond the zone traditionally thought to be affected by static stress changes. On this basis, they argued that dynamic stresses are responsible for triggering earthquakes. Richards-Dinger et al. (2010) and other studies, however, have presented several lines of evidence that suggest otherwise. One crucial question is whether the stacked distances of pairs of earthquakes, representing either mainshock-aftershock or foreshock-mainshock pairs, are in fact correctly identified and not misattributed, unrelated earthquakes. This question is especially important in the critical distance range of several to tens of earthquake radii, over which static stresses are thought to be too small to affect seismicity. If earthquake pairs in this range are not causally related, then the histogram of foreshock-mainshock and mainshock-aftershock pairs should be identical, and the difference between the two histograms can be used to identify remote triggering. Results based on southern Californian seismicity suggest that (1) the existence of a single power-law with a particular exponent may not be a robust observation, (2) geothermal regions seem to play an important role over the relevant distances, (3) remote triggering seems to exist beyond the classical static stress influence zone (perhaps out to 15 km after mainshocks with magnitudes between 3 and 4), (4) simple ETAS model simulations cannot reproduce all observations, and (5) at most one-third of the remote aftershocks had received significant static Coulomb stress

  19. Computational Software for Fitting Seismic Data to Epidemic-Type Aftershock Sequence Models

    NASA Astrophysics Data System (ADS)

    Chu, A.

    2014-12-01

    Modern earthquake catalogs are often analyzed using spatial-temporal point process models such as the epidemic-type aftershock sequence (ETAS) models of Ogata (1998). My work introduces software to implement two of ETAS models described in Ogata (1998). To find the Maximum-Likelihood Estimates (MLEs), my software provides estimates of the homogeneous background rate parameter and the temporal and spatial parameters that govern triggering effects by applying the Expectation-Maximization (EM) algorithm introduced in Veen and Schoenberg (2008). Despite other computer programs exist for similar data modeling purpose, using EM-algorithm has the benefits of stability and robustness (Veen and Schoenberg, 2008). Spatial shapes that are very long and narrow cause difficulties in optimization convergence and problems with flat or multi-modal log-likelihood functions encounter similar issues. My program uses a robust method to preset a parameter to overcome the non-convergence computational issue. In addition to model fitting, the software is equipped with useful tools for examining modeling fitting results, for example, visualization of estimated conditional intensity, and estimation of expected number of triggered aftershocks. A simulation generator is also given with flexible spatial shapes that may be defined by the user. This open-source software has a very simple user interface. The user may execute it on a local computer, and the program also has potential to be hosted online. Java language is used for the software's core computing part and an optional interface to the statistical package R is provided.

  20. Let's get technical: Enhancing program evaluation through the use and integration of internet and mobile technologies.

    PubMed

    Materia, Frank T; Miller, Elizabeth A; Runion, Megan C; Chesnut, Ryan P; Irvin, Jamie B; Richardson, Cameron B; Perkins, Daniel F

    2016-06-01

    Program evaluation has become increasingly important, and information on program performance often drives funding decisions. Technology use and integration can help ease the burdens associated with program evaluation by reducing the resources needed (e.g., time, money, staff) and increasing evaluation efficiency. This paper reviews how program evaluators, across disciplines, can apply internet and mobile technologies to key aspects of program evaluation, which consist of participant registration, participant tracking and retention, process evaluation (e.g., fidelity, assignment completion), and outcome evaluation (e.g., behavior change, knowledge gain). In addition, the paper focuses on the ease of use, relative cost, and fit with populations. An examination on how these tools can be integrated to enhance data collection and program evaluation is discussed. Important limitations of and considerations for technology integration, including the level of technical skill, cost needed to integrate various technologies, data management strategies, and ethical considerations, are highlighted. Lastly, a case study of technology use in an evaluation conducted by the Clearinghouse for Military Family Readiness at Penn State is presented and illustrates how technology integration can enhance program evaluation.

  1. Mobilizing communities for implementing evidence-based youth violence prevention programming: a commentary.

    PubMed

    Fixsen, Dean L; Blase, Karen A; Van Dyke, Melissa K

    2011-09-01

    Evidence-based programs have struggled for acceptance in human service settings. Information gleaned from these experiences indicates that implementation is the missing link in the science to service chain. The science and practice of implementation is progressing and can inform approaches to full and effective uses of youth violence prevention programs nationally. Implementation Teams that know (a) innovations, (b) implementation best practices, and (c) improvement cycles are essential to mobilizing support for successful uses of evidence-based programs on a socially significant scale. The next wave of development in implementation science and practice is underway: establishing infrastructures for implementation to make implementation expertise available to communities nationally. Good science, implemented well in practice, can benefit all human services, including youth violence prevention.

  2. Assisted early mobility for hospitalized older veterans: preliminary data from the STRIDE program.

    PubMed

    Hastings, S Nicole; Sloane, Richard; Morey, Miriam C; Pavon, Juliessa M; Hoenig, Helen

    2014-11-01

    An important contributor to hospital-associated disability is immobility during hospitalization. Preliminary results from STRIDE, a clinical demonstration program of supervised walking for older adults admitted to the hospital with medical illness, are reported. The STRIDE program consisted of a targeted gait and balance assessment by a physical therapist, followed by daily walks supervised by a recreation therapy assistant for the duration of the hospital stay. To examine program effectiveness, STRIDE participants (n = 92) were compared with individuals referred but not enrolled (because of refusal or because program was at capacity, n = 35). Median length of stay was 4.7 days for STRIDE participants and 5.7 days for individuals receiving usual care (P = .31). There was one inpatient fall in each group (not associated with a STRIDE walk). Overall, 92% of STRIDE participants were discharged to home (rather than a skilled nursing facility (SNF)) compared to 74% of individuals receiving usual care (P = .007). Thirty-day emergency department visit rates and readmission rates were not significantly different between the two groups. STRIDE, a supervised walking program for hospitalized older adults, was feasible and safe, and program participants were less likely to be discharged to a SNF than a demographically similar comparison group. STRIDE is a promising interdisciplinary approach to promoting mobility and improving outcomes in hospitalized older adults.

  3. Mobile and replicated alignment of arrays in data-parallel programs

    NASA Technical Reports Server (NTRS)

    Chatterjee, Siddhartha; Gilbert, John R.; Schreiber, Robert

    1993-01-01

    When a data-parallel language like FORTRAN 90 is compiled for a distributed-memory machine, aggregate data objects (such as arrays) are distributed across the processor memories. The mapping determines the amount of residual communication needed to bring operands of parallel operations into alignment with each other. A common approach is to break the mapping into two stages: first, an alignment that maps all the objects to an abstract template, and then a distribution that maps the template to the processors. We solve two facets of the problem of finding alignments that reduce residual communication: we determine alignments that vary in loops, and objects that should have replicated alignments. We show that loop-dependent mobile alignment is sometimes necessary for optimum performance, and we provide algorithms with which a compiler can determine good mobile alignments for objects within do loops. We also identify situations in which replicated alignment is either required by the program itself (via spread operations) or can be used to improve performance. We propose an algorithm based on network flow that determines which objects to replicate so as to minimize the total amount of broadcast communication in replication. This work on mobile and replicated alignment extends our earlier work on determining static alignment.

  4. Using Internet and Mobile Phone Technology to Deliver an Automated Physical Activity Program: Randomized Controlled Trial

    PubMed Central

    Catt, Michael; De Boni, Marco; Fairley, Bruce William; Hurst, Tina; Murray, Peter; Richardson, Alannah; Sodhi, Jaspreet Singh

    2007-01-01

    Background The Internet has potential as a medium for health behavior change programs, but no controlled studies have yet evaluated the impact of a fully automated physical activity intervention over several months with real-time objective feedback from a monitor. Objective The aim was to evaluate the impact of a physical activity program based on the Internet and mobile phone technology provided to individuals for 9 weeks. Methods A single-center, randomized, stratified controlled trial was conducted from September to December 2005 in Bedfordshire, United Kingdom, with 77 healthy adults whose mean age was 40.4 years (SD = 7.6) and mean body mass index was 26.3 (SD = 3.4). Participants were randomized to a test group that had access to an Internet and mobile phone–based physical activity program (n = 47) or to a control group (n = 30) that received no support. The test group received tailored solutions for perceived barriers, a schedule to plan weekly exercise sessions with mobile phone and email reminders, a message board to share their experiences with others, and feedback on their level of physical activity. Both groups were issued a wrist-worn accelerometer to monitor their level of physical activity; only the test group received real-time feedback via the Internet. The main outcome measures were accelerometer data and self-report of physical activity. Results At the end of the study period, the test group reported a significantly greater increase over baseline than did the control group for perceived control (P < .001) and intention/expectation to exercise (P < .001). Intent-to-treat analyses of both the accelerometer data (P = .02) and leisure time self-report data (P = .03) found a higher level of moderate physical activity in the test group. The average increase (over the control group) in accelerometer-measured moderate physical activity was 2 h 18 min per week. The test group also lost more percent body fat than the control group (test group: −2

  5. Seven Years Later: Effects of a Neighborhood Mobility Program on Poor Black and Latino Adults' Well-Being

    ERIC Educational Resources Information Center

    Fauth, Rebecca C.; Leventhal, Tama; Brooks-Gunn, Jeanne

    2008-01-01

    This study explored program effects on adults' well-being seven years following the implementation of a court-ordered neighborhood mobility program. Low-income black and Latino adults residing in poor, segregated neighborhoods in Yonkers, New York were randomly selected to relocate to publicly funded town-houses in middle-class neighborhoods…

  6. A spatial decision support system prototype for housing mobility program planning

    NASA Astrophysics Data System (ADS)

    Johnson, Michael P.

    This paper presents a GIS-based decision support system prototype intended for use by public housing authority (PHA) administrators and planners designing policy for housing mobility programs. Housing mobility programs enable low-income families, many of whom live in government-operated public housing, to move to more desirable private-market rentals via rent subsidies. Unfortunately, housing authority planners have limited ability to visualize alternative relocation schemes of cohorts of low-income families or the impacts associated with these relocation policies. Thus, they are often not able to give highest-quality advice to clients regarding places to search for private-market rental housing. Housing Location Planner assists PHA planners in three ways: it analyzes spatial, demographic and housing market characteristics of the study area, selects certain portions of the study area for input to an optimization model which generates alternative family allocations, and displays optimization model results in a way that links decision variable values and objective function values. Housing Location Planner is seen as a first step in the development of even more sophisticated multi-stakeholder spatial decision support systems for subsidized housing planning in which one or more alternative allocations of families across a study area is chosen as a basis for policy initiatives.

  7. Aftershocks can Significantly Alter Stress Change Patterns Produced by Their Mainshock

    NASA Astrophysics Data System (ADS)

    Felzer, K. R.; Becker, T. W.; Abercrombie, R. E.; Ekström, G.; Rice, J. R.

    2001-12-01

    Many studies over the last decade have used the static Coulomb stress change produced by a mainshock to predict the locations of triggered earthquakes. This method has shown some success, but often fails to predict the locations of 20% to 40% of the aftershocks of a given mainshock. We use statistical Monte Carlo modeling to show that this amount of failure is consistent with the perturbation to the stress field provided by the aftershocks themselves. Although most aftershocks are more than a magnitude unit smaller than their mainshocks, the ability of earthquakes of all magnitudes to produce large static stress changes at short range, and the pronounced clustering of aftershock hypocenters, implies that many aftershock hypocenters in a sequence may be primarily stressed by a previous aftershock rather than by the mainshock itself. The exact percentage stressed by previous aftershocks increases with the activity of the aftershock sequence, the magnitude of the mainshock, and the time since the mainshock. Our model predicts that two days after the average California M7 earthquake, for example, over 50% of new aftershocks are primarily in response to stress changes from previous aftershocks. This means that the majority of the new aftershocks are most likely to occur near previous aftershocks, and not necessarily within regions of Coulomb stress increase from the mainshock. The same happens three days after the average M6, and three weeks after the average M5 mainshock. Our statistical modeling uses Omori's Law for aftershock decay, the Gutenberg-Richter magnitude frequency relationship, Baath's Law, and the assumptions that earthquakes of all sizes are capable of generating aftershocks and that the timing of each aftershock is essentially determined by a single mainshock. We apply our model to the 1999 M7.1 Hector Mine earthquake, which may be classified as an aftershock of the 1992 M7.3 Landers earthquake. Our modeling shows that at the time of the Hector Mine

  8. The Hellenic Seismological Network Of Crete (HSNC): Validation and results of the 2013 aftershock sequences

    NASA Astrophysics Data System (ADS)

    Chatzopoulos, Georgios; Papadopoulos, Ilias; Vallianatos, Filippos

    2015-04-01

    The number and quality of seismological networks in Europe has increased in the past decades. Nevertheless, the need for localized networks monitoring areas of great seismic and scientific interest is constant. Hellenic Seismological Network of Crete (HSNC) covers this need for the vicinity of the South Aegean Sea and Crete Island. In the present work with the use of Z-map software (www.seismo.ethz.ch) the spatial variability of Magnitude of Completeness (Mc) is calculated from HSNC's manual analysis catalogue of events for the period 2011 until today, proving the good coverage of HSNC in the areas. Furthermore the 2013, South Aegean seismicity where two large shallow earthquakes occurred in the vicinity of Crete Island, is discussed. The first event takes place on 15th June 2013 in the front of the Hellenic Arc, south from central Crete, while the second one on 12th October, 2013 on the western part of Crete. The two main shocks and their aftershock sequences have been relocated with the use of hypoinverse earthquake location software and an appropriate crust model. The HSNC identified more than 500 and 300 aftershocks respectively followed after the main events. The detailed construction of aftershocks catalogue permits the applicability of modern theories based on complexity sciences as described recently in the frame of non extensive statistical physics. In addition site effects in the stations locations are presented using event and noise recordings. This work was implemented through the project IMPACT-ARC in the framework of action "ARCHIMEDES III-Support of Research Teams at TEI of Crete" (MIS380353) of the Operational Program "Education and Lifelong Learning" and is co-financed by the European Union (European Social Fund) and Greek national funds References A. Tzanis and F. Vallianatos, "Distributed power-law seismicity changes and crustal deformation in the EW Hellenic Arc", Natural Hazards and Earth Systems Sciences, 3, 179-195, 2003 F. Vallianatos, G

  9. Mobile health in China: a review of research and programs in medical care, health education, and public health.

    PubMed

    Corpman, David W

    2013-01-01

    There are nearly 1 billion mobile phone subscribers in China. Health care providers, telecommunications companies, technology firms, and Chinese governmental organizations use existing mobile technology and social networks to improve patient-provider communication, promote health education and awareness, add efficiency to administrative practices, and enhance public health campaigns. This review of mobile health in China summarizes existing clinical research and public health text messaging campaigns while highlighting potential future areas of research and program implementation. Databases and search engines served as the primary means of gathering relevant resources. Included material largely consists of scientific articles and official reports that met predefined inclusion criteria. This review includes 10 reports of controlled studies that assessed the use of mobile technology in health care settings and 17 official reports of public health awareness campaigns that used text messaging. All source material was published between 2006 and 2011. The controlled studies suggested that mobile technology interventions significantly improved an array of health care outcomes. However, additional efforts are needed to refine mobile health research and better understand the applicability of mobile technology in China's health care settings. A vast potential exists for the expansion of mobile health in China, especially as costs decrease and increasingly sophisticated technology becomes more widespread.

  10. Spatial correlation of aftershock locations and on-fault main shock properties

    NASA Astrophysics Data System (ADS)

    Woessner, J.; Schorlemmer, D.; Wiemer, S.; Mai, P. M.

    2006-08-01

    We quantify the correlation between spatial patterns of aftershock hypocenter locations and the distribution of coseismic slip and stress drop on a main shock fault plane using two nonstandard statistical tests. Test T1 evaluates if aftershock hypocenters are located in low-slip regions (hypothesis H1), test T2 evaluates if aftershock hypocenters occur in regions of increased shear stress (hypothesis H2). In the tests, we seek to reject the null hypotheses H0: Aftershock hypocenters are not correlated with (1) low-slip regions or (2) regions of increased shear stress, respectively. We tested the hypotheses on four strike-slip events for which multiple earthquake catalogs and multiple finite fault source models of varying accuracy exist. Because we want to retain earthquake clustering as the fundamental feature of aftershock seismicity, we generate slip distributions using a random spatial field model and derive the stress drop distributions instead of generating seismicity catalogs. We account for uncertainties in the aftershock locations by simulating them within their location error bounds. Our findings imply that aftershocks are preferentially located in regions of low-slip (u ≤ ?umax) and of increased shear stress (Δσ < 0). In particular, the correlation is more significant for relocated than for general network aftershock catalogs. However, the results show that stress drop patterns provide less information content on aftershock locations. This implies that static shear stress change of the main shock may not be the governing process for aftershock genesis.

  11. Decay of aftershock density with distance indicates triggering by dynamic stress.

    PubMed

    Felzer, K R; Brodsky, E E

    2006-06-01

    The majority of earthquakes are aftershocks, yet aftershock physics is not well understood. Many studies suggest that static stress changes trigger aftershocks, but recent work suggests that shaking (dynamic stresses) may also play a role. Here we measure the decay of aftershocks as a function of distance from magnitude 2-6 mainshocks in order to clarify the aftershock triggering process. We find that for short times after the mainshock, when low background seismicity rates allow for good aftershock detection, the decay is well fitted by a single inverse power law over distances of 0.2-50 km. The consistency of the trend indicates that the same triggering mechanism is working over the entire range. As static stress changes at the more distant aftershocks are negligible, this suggests that dynamic stresses may be triggering all of these aftershocks. We infer that the observed aftershock density is consistent with the probability of triggering aftershocks being nearly proportional to seismic wave amplitude. The data are not fitted well by models that combine static stress change with the evolution of frictionally locked faults.

  12. Decay of aftershock density with distance indicates triggering by dynamic stress

    USGS Publications Warehouse

    Felzer, K.R.; Brodsky, E.E.

    2006-01-01

    The majority of earthquakes are aftershocks, yet aftershock physics is not well understood. Many studies suggest that static stress changes trigger aftershocks, but recent work suggests that shaking (dynamic stresses) may also play a role. Here we measure the decay of aftershocks as a function of distance from magnitude 2-6 mainshocks in order to clarify the aftershock triggering process. We find that for short times after the mainshock, when low background seismicity rates allow for good aftershock detection, the decay is well fitted by a single inverse power law over distances of 0.2-50 km. The consistency of the trend indicates that the same triggering mechanism is working over the entire range. As static stress changes at the more distant aftershocks are negligible, this suggests that dynamic stresses may be triggering all of these aftershocks. We infer that the observed aftershock density is consistent with the probability of triggering aftershocks being nearly proportional to seismic wave amplitude. The data are not fitted well by models that combine static stress change with the evolution of frictionally locked faults. ?? 2006 Nature Publishing Group.

  13. The Tuscan Mobile Simulation Program: a description of a program for the delivery of in situ simulation training.

    PubMed

    Ullman, Edward; Kennedy, Maura; Di Delupis, Francesco Dojmi; Pisanelli, Paolo; Burbui, Andrea Giuliattini; Cussen, Meaghan; Galli, Laura; Pini, Riccardo; Gensini, Gian Franco

    2016-09-01

    Simulation has become a critical aspect of medical education. It allows health care providers the opportunity to focus on safety and high-risk situations in a protected environment. Recently, in situ simulation, which is performed in the actual clinical setting, has been used to recreate a more realistic work environment. This form of simulation allows for better team evaluation as the workers are in their traditional roles, and can reveal latent safety errors that often are not seen in typical simulation scenarios. We discuss the creation and implementation of a mobile in situ simulation program in emergency departments of three hospitals in Tuscany, Italy, including equipment, staffing, and start-up costs for this program. We also describe latent safety threats identified in the pilot in situ simulations. This novel approach has the potential to both reduce the costs of simulation compared to traditional simulation centers, and to expand medical simulation experiences to providers and healthcare organizations that do not have access to a large simulation center.

  14. The Impact of Using Mobile-Enabled Devices on Patient Engagement in Remote Monitoring Programs

    PubMed Central

    Agboola, Stephen; Havasy, Rob; Myint-U, Khinlei; Kvedar, Joseph; Jethwani, Kamal

    2013-01-01

    Background: Different types of data transmission technologies are used in remote monitoring (RM) programs. This study reports on a retrospective analysis of how participants engage, based on the type of data transfer technology used in a blood pressure (BP) RM program, and its potential impact on RM program design and outcomes. Methods: Thirty patients, aged 23–84 years (62 ± 14 years), who had completed at least 2 months in the program and were not participating in any other clinical trial were identified from the Remote Monitoring Data Repository. Half of these patients used wireless-based data transfer devices [wireless-based device (WBD)] while the other half used telephone modem-based data transfer devices [modem-based device (MBD)]. Participants were matched by practice and age. Engagement indices, which include frequency of BP measurements, frequency of data uploads, time to first BP measurement, and time to first data upload, were compared in both groups using the Wilcoxon–Mann–Whitney two-sample rank-sum test. Help desk call data were analyzed by Chi square test. Results: The frequency of BP measurements and data uploads was significantly higher in the WBD group versus the MBD group [median = 0.66 versus 0.2 measurements/day (p =.01) and 0.46 versus 0.01 uploads/day (p <.001), respectively]. Time to first upload was significantly lower in the WBD group (median = 4 versus 7 days; p =.02), but time to first BP measurement did not differ between the two groups (median = 2 versus 1 day; p =.98). Conclusion: Wireless transmission ensures instantaneous transmission of readings, providing clinicians timely data to intervene on. Our findings suggest that mobile-enabled wireless technologies can positively impact patient engagement, outcomes, and operational workflow in RM programs. PMID:23759394

  15. High Frequency Monitoring Reveals Aftershocks in Subcritical Crack Growth

    NASA Astrophysics Data System (ADS)

    Stojanova, M.; Santucci, S.; Vanel, L.; Ramos, O.

    2014-03-01

    By combining direct imaging and acoustic emission measurements, the subcritical propagation of a crack in a heterogeneous material is analyzed. Both methods show that the fracture proceeds through a succession of discrete events. However, the macroscopic opening of the fracture captured by the images results from the accumulation of more-elementary events detected by the acoustics. When the acoustic energy is cumulated over large time scales corresponding to the image acquisition rate, a similar statistics is recovered. High frequency acoustic monitoring reveals aftershocks responsible for a time scale dependent exponent of the power law energy distributions. On the contrary, direct imaging, which is unable to resolve these aftershocks, delivers a misleading exponent value.

  16. Triggered Swarms and Induced Aftershock Sequences in Geothermal Systems

    NASA Astrophysics Data System (ADS)

    Shcherbakov, R.; Turcotte, D. L.; Yikilmaz, M. B.; Kellogg, L. H.; Rundle, J. B.

    2015-12-01

    Natural geothermal systems, which are used for energy generation, are usually associated with high seismic activity. This can be related to the large-scale injection and extraction of fluids to enhance geothermal recovery. This results in the changes of the pore pressure and pore-elastic stress field and can stimulate the occurrence of earthquakes. These systems are also prone to triggering of seismicity by the passage of seismic waves generated by large distant main shocks. In this study, we analyze clustering and triggering of seismicity at several geothermal fields in California. Particularly, we consider the seismicity at the Geysers, Coso, and Salton Sea geothermal fields. We analyze aftershock sequences generated by local large events with magnitudes greater than 4.0 and earthquake swarms generated by several significant long distant main shocks. We show that the rate of the aftershock sequences generated by the local large events in the two days before and two days after the reference event can be modelled reasonably well by the time dependent Epidemic Type Aftershock Sequence (ETAS) model. On the other hand, the swarms of activity triggered by large distant earthquakes cannot be described by the ETAS model. To model the increase in the rate of seismicity associated with triggering by large distant main shocks we introduce an additional time-dependent triggering mechanism into the ETAS model. In almost all cases the frequency-magnitude statistics of triggered sequences follow Gutenberg-Richter scaling to a good approximation. The analysis indicates that the seismicity triggered by relatively large local events can initiate sequences similar to regular aftershock sequences. In contrast, the distant main shocks trigger swarm like activity with faster decaying rates.

  17. Disease aftershocks - The health effects of natural disasters

    USGS Publications Warehouse

    Guptill, S.C.

    2001-01-01

    While the initial activity of a natural disaster event may directly injure or kill a number of people, it is possible that a significant number of individuals will be affected by disease outbreaks that occur after the first effects of the disaster have passed. Coupling the epidemiologist's knowledge of disease outbreaks with geographic information systems and remote sensing technology could help natural disaster relief workers to prevent additional victims from disease aftershocks.

  18. Iterative Strategies for Aftershock Classification in Automatic Seismic Processing Pipelines

    NASA Astrophysics Data System (ADS)

    Gibbons, Steven J.; Kværna, Tormod; Harris, David B.; Dodge, Douglas A.

    2016-04-01

    Aftershock sequences following very large earthquakes present enormous challenges to near-realtime generation of seismic bulletins. The increase in analyst resources needed to relocate an inflated number of events is compounded by failures of phase association algorithms and a significant deterioration in the quality of underlying fully automatic event bulletins. Current processing pipelines were designed a generation ago and, due to computational limitations of the time, are usually limited to single passes over the raw data. With current processing capability, multiple passes over the data are feasible. Processing the raw data at each station currently generates parametric data streams which are then scanned by a phase association algorithm to form event hypotheses. We consider the scenario where a large earthquake has occurred and propose to define a region of likely aftershock activity in which events are detected and accurately located using a separate specially targeted semi-automatic process. This effort may focus on so-called pattern detectors, but here we demonstrate a more general grid search algorithm which may cover wider source regions without requiring waveform similarity. Given many well-located aftershocks within our source region, we may remove all associated phases from the original detection lists prior to a new iteration of the phase association algorithm. We provide a proof-of-concept example for the 2015 Gorkha sequence, Nepal, recorded on seismic arrays of the International Monitoring System. Even with very conservative conditions for defining event hypotheses within the aftershock source region, we can automatically remove over half of the original detections which could have been generated by Nepal earthquakes and reduce the likelihood of false associations and spurious event hypotheses. Further reductions in the number of detections in the parametric data streams are likely using correlation and subspace detectors and/or empirical matched

  19. Direct test of static stress versus dynamic stress triggering of aftershocks

    USGS Publications Warehouse

    Pollitz, F.F.; Johnston, M.J.S.

    2006-01-01

    Aftershocks observed over time scales of minutes to months following a main shock are plausibly triggered by the static stress change imparted by the main shock, dynamic shaking effects associated with passage of seismic waves from the main shock, or a combination of the two. We design a direct test of static versus dynamic triggering of aftershocks by comparing the near-field temporal aftershock patterns generated by aseismic and impulsive events occurring in the same source area. The San Juan Bautista, California, area is ideally suited for this purpose because several events of both types of M???5 have occurred since 1974. We find that aftershock rates observed after impulsive events are much higher than those observed after aseismic events, and this pattern persists for several weeks after the event. This suggests that, at least in the near field, dynamic triggering is the dominant cause of aftershocks, and that it generates both immediate and delayed aftershock activity.

  20. Evidence Against the New Madrid Long-Lived Aftershock Hypothesis

    NASA Astrophysics Data System (ADS)

    Page, M. T.; Hough, S. E.

    2014-12-01

    It has been suggested that continuing seismicity in the New Madrid, central U.S. region is primarily composed of the continuing long-lived aftershock sequence of the 1811-1812 sequence, and thus cannot be taken as an indication of present-day strain accrual in the region. We examine historical and instrumental seismicity in the New Madrid region to determine if such a model is feasible given 1) the observed protracted nature of past New Madrid sequences, with multiple mainshocks with apparently similar magnitudes; 2) historical rates of M≥6 earthquakes after the initial activity in 1811-1812; and 3) the modern seismicity rate in the region. We use ETAS modeling to search for sub-critical sets of direct Omori parameters that are consistent with all of these datasets, given a realistic consideration of their uncertainties. High aftershock productivity is required both to match the observation of multiple mainshocks and to explain the modern level of activity as aftershocks; synthetic sequences consistent with these observations substantially overpredict the number of events of M≥6 that were observed in the past 200 years. Our results imply that ongoing background seismicity in the New Madrid region is driven by ongoing strain accrual processes and that, despite low deformation rates, seismic activity in the zone is not decaying with time.

  1. Programs.

    ERIC Educational Resources Information Center

    Community College Journal, 1996

    1996-01-01

    Includes a collection of eight short articles describing model community college programs. Discusses a literacy program, a mobile computer classroom, a support program for at-risk students, a timber-harvesting program, a multimedia presentation on successful women graduates, a career center, a collaboration with NASA, and an Israeli engineering…

  2. Self-Study and Evaluation Guide/1968 Edition. Section D-2B: Orientation on Mobility Services. (Dog Guide Program Only).

    ERIC Educational Resources Information Center

    National Accreditation Council for Agencies Serving the Blind and Visually Handicapped, New York, NY.

    This self-study and evaluation guide on orientation and mobility services (dog guide program emphasis) is one of 28 guides designed for organizations undertaking a self-study as part of the process for accreditation from the National Accreditation Council (NAC) for agencies serving the blind and visually handicapped. Provided are lists of…

  3. Understanding the Programmatic and Contextual Forces That Influence Participation in a Government-Sponsored International Student-Mobility Program

    ERIC Educational Resources Information Center

    Perna, Laura W.; Orosz, Kata; Jumakulov, Zakir; Kishkentayeva, Marina; Ashirbekov, Adil

    2015-01-01

    Although prior research establishes the forces that "push" and "pull" students to participate in foreign study, the transferability of findings from earlier studies is limited by the absence of theoretical grounding. In addition, relatively little is known about how a government-sponsored student mobility program promotes…

  4. Shocks and Aftershocks: France Confronts Its Past.

    ERIC Educational Resources Information Center

    Bracher, Nathan; Golsan, Richard

    1995-01-01

    Maintains that events in France during and after World War II are still controversial political and social issues. Describes the program and activities of U.S. teachers during a summer seminar on French literature and filmmaking during the German occupation years. (CFR)

  5. Transforming a Traditional Personnel Preparation Program in Orientation and Mobility into an Online Program at the University of Arkansas at Little Rock

    ERIC Educational Resources Information Center

    Jacobson, William H.

    2005-01-01

    The University of Arkansas at Little Rock (UALR) has offered a personnel preparation program in orientation and mobility (O&M) since 1975. Since that time, nearly 400 individuals from the United States and numerous foreign countries have either received degrees or have become eligible for national U.S. certification in O&M. However, it became…

  6. Anomalous stress diffusion, Omori's law and Continuous Time Random Walk in the 2010 Efpalion aftershock sequence (Corinth rift, Greece)

    NASA Astrophysics Data System (ADS)

    Michas, Georgios; Vallianatos, Filippos; Karakostas, Vassilios; Papadimitriou, Eleftheria; Sammonds, Peter

    2014-05-01

    result that is in accordance to earthquake triggering in global scale (Huc and Main, 2003) and aftershocks diffusion in California (Helmstetter et al., 2003). While other mechanisms may be plausible, the results indicate that anomalous stress transfer due to the occurrence of the two major events control the migration of the aftershock activity, activating different fault segments and having strong implications for the seismic hazard of the area. Acknowledgments. G. Michas wishes to acknowledge the partial financial support from the Greek State Scholarships Foundation (IKY). This work has been accomplished in the framework of the postgraduate program and co-funded through the action "Program for scholarships provision I.K.Y. through the procedure of personal evaluation for the 2011-2012 academic year" from resources of the educational program "Education and Life Learning" of the European Social Register and NSRF 2007- 2013. References Ganas, A., Chousianitis, K., Batsi, E., Kolligri, M., Agalos, A., Chouliaras, G., Makropoulos, K. (2013). The January 2010 Efpalion earthquakes (Gulf of Corinth, central Greece): Earthquake interactions and blind normal faulting. J. of Seism., 17(2), 465-484. Helmstetter, A., Ouillon, G., Sornette, D. (2003). Are aftershocks of large California earthquakes diffusing? J. of Geophys. Res. B, 108(10), 2483. Huc, M., Main, I. G. (2003). Anomalous stress diffusion in earthquake triggering: Correlation length, time dependence, and directionality. J. of Geophys. Res. B, 108(7), 2324. Karakostas, V., Karagianni, E., Paradisopoulou, P. (2012). Space-time analysis, faulting and triggering of the 2010 earthquake doublet in western Corinth gulf. Nat.Haz., 63(2), 1181-1202. Metzler, R., Klafter, J. (2000). The random walk's guide to anomalous diffusion: a fractional dynamics approach. Physics Reports, 339, 1-77. Michas, G., Vallianatos, F., Sammonds, P. (2013). Non-extensivity and long-range correlations in the earthquake activity at the West Corinth

  7. Non extensive statistical physics properties of the 2003 (Mw6.2), Lefkada, Ionian island Greece, aftershock sequence

    NASA Astrophysics Data System (ADS)

    Vallianatos, F.; Karakostas, V.; Papadimitriou, E.

    2012-04-01

    On 14 August 2003, Lefkada Island (Central Ionian) was affected by an Mw=6.2 earthquake. Due to a dense temporary seismic network that operating immediately after the main shock occurrence, hundreds of aftershocks were recorded and located with high precision whereas relocation of the main shock and early strong aftershocks became also feasible. Thus, the spatio-temporal distribution of aftershocks onto the main and the neighboring fault segments was investigated in detail enabling the recognition of four distinctive seismicity clusters separated by less active patches. The aftershock spatiotemporal properties studied here using the concept of Non-Extensive Statistical Physics (NESP). The cumulative distribution functions of the inter-event times and the inter-event distances are estimated for the data set in each seismicity cluster and the analysis results to a value of the statistical thermodynamic qT and qD parameters for each cluster, where qT varies from 1.15 to 1.47 and qD from 0.5 to 0.77 for the interevent times and distances distributions respectively. These values confirm the complexity and non-additivity of the spatiotemporal evolution of seismicity and the usefulness of NESP in investigating such phenomena. The temporal structure is also discussed using the complementary to NESP approach of superstatistics, which is based on a superposition of ordinary local equilibrium statistical mechanics. The result indicates that the temporal evolution of the Lefkada aftershock sequence in clusters A, B and C governed by very low number of degrees of freedom while D is less organized seismicity structure with a much higher number of degrees of freedom. Acknowledgments. This work was supported in part by the THALES Program of the Ministry of Education of Greece and the European Union in the framework of the project entitled "Integrated understanding of Seismicity, using innovative Methodologies of Fracture mechanics along with Earthquake and non extensive

  8. The development of a mobile u-Health program and evaluation for self-diet management for diabetic patients

    PubMed Central

    Ahn, Yun; Bae, Jeahurn

    2016-01-01

    BACKGROUND/OBJECTIVES This study aims to develop a mobile nutritional management program for integration into the already developed web-based program, Diabetes Mellitus Dietary Management Guide (DMDMG) for diabetic patients. Further, we aim to evaluate the amended DMDMG program. SUBJECTS/METHODS The mobile application based on an Android operating system includes three parts: 1) record of diet intake, which allows users to take pictures of the meal and save to later add diet records into DMDMG; 2) an alarm system that rings at each meal time, which reminds users to input the data; 3) displays the diet record and the results of nutrient intake, which can be also viewed through the web program. All three parts are linked to the web-based program. A survey was conducted to evaluate the program in terms of nutrition knowledge, dietary attitude, eating behavior and diet intake by non-equivalent control group design among diabetic patients with 14 DMDMG users and 12 non-user controls after a one-month trial of DMDMG. RESULTS Non-users did not use the program, but participated in the weekly off-line nutrition classes for one month. The program users showed increased healthful dietary behavior (P < 0.01) and dietary attitude scores (P < 0.05). More DMDMG users had higher nutrition knowledge scores after one-month trial than non-users. However, dietary intake significantly increased in non-user group for calcium and sodium (P < 0.05) while the user group did not show significant changes. CONCLUSIONS The program has created positive changes in patients' dietary life. All the users were satisfied with the program, although some expressed minor difficulties with an unfamiliar mobile app. PMID:27247732

  9. Aftershocks of the 2014 South Napa, California, Earthquake: Complex faulting on secondary faults

    USGS Publications Warehouse

    Hardebeck, Jeanne L.; Shelly, David R.

    2016-01-01

    We investigate the aftershock sequence of the 2014 MW6.0 South Napa, California, earthquake. Low-magnitude aftershocks missing from the network catalog are detected by applying a matched-filter approach to continuous seismic data, with the catalog earthquakes serving as the waveform templates. We measure precise differential arrival times between events, which we use for double-difference event relocation in a 3D seismic velocity model. Most aftershocks are deeper than the mainshock slip, and most occur west of the mapped surface rupture. While the mainshock coseismic and postseismic slip appears to have occurred on the near-vertical, strike-slip West Napa fault, many of the aftershocks occur in a complex zone of secondary faulting. Earthquake locations in the main aftershock zone, near the mainshock hypocenter, delineate multiple dipping secondary faults. Composite focal mechanisms indicate strike-slip and oblique-reverse faulting on the secondary features. The secondary faults were moved towards failure by Coulomb stress changes from the mainshock slip. Clusters of aftershocks north and south of the main aftershock zone exhibit vertical strike-slip faulting more consistent with the West Napa Fault. The northern aftershocks correspond to the area of largest mainshock coseismic slip, while the main aftershock zone is adjacent to the fault area that has primarily slipped postseismically. Unlike most creeping faults, the zone of postseismic slip does not appear to contain embedded stick-slip patches that would have produced on-fault aftershocks. The lack of stick-slip patches along this portion of the fault may contribute to the low productivity of the South Napa aftershock sequence.

  10. Structure of the Aftershock Zone of the Mw 7.0 Haiti Earthquake from the USGS-BME Portable Instrument Deployment

    NASA Astrophysics Data System (ADS)

    Altidor, J.; Dieuseul, A.; Armbruster, J. G.; Benz, H.; Dietel, C.; Ellsworth, W. L.; Given, D.; Hough, S. E.; Ketchum, D.; Luetgert, J. H.; Maharrey, J. Z.; Meremonte, M. E.; McNamara, D. E.; Mildor, B. S.; Mooney, W. D.; Sell, R.

    2010-12-01

    Between mid-March and early-June 2010, the U.S. Geological Survey (USGS) in partnership with the Bureau des Mines et de l’Energie (BME) operated an 8-station network of high-gain, three-component continuously recording stations to record the aftershocks of the January 12, 2010 Mw 7.0 Haiti earthquake. The stations were deployed to complement stations installed previously by USGS/EERI, Canadian and French teams. The USGS-BME deployment was specifically designed to improve the north-south control of epicentral locations and to investigate their association with the Enriquillo-Plantain Garden Fault and blind faults inferred from coastal uplift and InSAR imagery. Three of the instruments were located north of the aftershock zone, including one on the island La Gonave, and three were located on the southern coast of Haiti. The remaining two were deployed near the middle of the aftershock zone. P- and S- arrival times were jointly inverted for hypocenters and a layered crustal model using program VELEST. The epicenters are aligned along an 80-km-long belt striking parallel to, but distinctly north of the surface trace of the Enriquillo Fault. Well-constrained focal depths extend to at least 20 km depth. Epicentral locations are 10 or more km north of locations determined using teleseismic data and suggest that previously reported locations for the main shock and large aftershocks will need to be revised. The principal internal structure of the aftershock zone that can be resolved at present is a sharp southern boundary to the zone between 3 and 20 km depth that dips 75 degrees to the north with a surface projection that approximately coincides with the mapped trace of the Enriquillo Fault.

  11. The Importance of Small Aftershocks for Earthquake Triggering

    NASA Astrophysics Data System (ADS)

    Woessner, Jochen; Meier, Men-Andrin; Werner, Max; Wiemer, Stefan

    2013-04-01

    Earthquakes occur in response to changes in the crust's stress state, however, the full picture of the causative process for earthquake triggering remains unclear. Many researchers have employed Coulomb stress change theory, which quantifies the changes in static Coulomb stress from nearby ruptures. This theory seems to at least partly explain the spatial patterns of triggered earthquakes, in particular during aftershock sequences and along faults. Several assumptions are needed to facilitate the calculation of stress changes. Here, we challenge the typical neglect of stress changes induced by the small but numerous and strongly clustered aftershocks during the evolution of the sequence. Both empirical observations and a simple scaling law suggest that this neglect may not be justified. We estimate the evolution of Coulomb stress changes during the 1992 Mw 7.3 Landers earthquake sequence by including the effect of the detected aftershocks using the focal mechanisms from the recently updated Southern California catalog. This estimation is hampered by that only 62% of located events from our study window have a focal mechanism, by the neglect of events that are too small to be detected and by the unreliability of near-field stress change estimations. As a consequence, we are limited to analyzing only a part of the full stress change signal imparted by small events. Despite these shortcomings, our calculations suggest that small to moderate events strongly dominate static stress redistribution in dense secondary aftershock clusters. However, their relative importance varies over space and is, on average, smaller than the main shock contribution. Furthermore, we find that aftershocks - with their reported relative orientations and positions - impose more often positive than negative stress changes, which is what would be expected if they were actively involved in triggering processes. However, this effect appears to be limited to event pairs with inter-event distances

  12. A Rapid Deployment Seismological network (RaDeSeis) for real time aftershock studies

    NASA Astrophysics Data System (ADS)

    Hloupis, G.; Vallianatos, F.; Makris, J. P.

    2009-04-01

    The understanding of earthquake faulting process is one of the main factors that contribute to earthquake damage. One of the most valuable and essential tools for the understanding of faulting process in the analysis of aftershocks. The critical point for successful aftershock studies is the mobile seismological network that will deployed in order to provide the required data. The main problem that arise for these networks is how fast the recorded data are available to data centres in order to estimate the focal mechanisms, the source parameters estimation as well as to examine microseismic activity. The ideal situation is to have these data available in real time but this is limited by the different telemetry requirements for every individual installation. Based on the experience gained from several installations in Hellenic Seismological Network of Crete (HSNC) we propose a mobile network scheme (called RaDeSeis) capable of installed in a limited amount of time and provide real time seismological data. RaDeSeis is an hybrid network based on VSAT and WiFi communication links between seismological stations and data centre. The network is deployed in star topology where the central station is the communication hub at the same time. Dedicated point-to-point links between central station and border station established using WiFi links. Communication between central station and data centre is established by VSAT. With appropriate routing on central station the data centre is collecting, control and monitor all the stations from the area of interest in real time. In order to decrease the time needed for each installation a specific software (RaLiEs - Rapid Link Establishment) is originated for the quicker link establishment between border stations and central station (with an average distance of 40km LOS) as well as to data centre. By using this software each telecommunication installation needs less than half an hour to complete the necessary link adjustments

  13. Magnitude estimates of two large aftershocks of the 16 December 1811 New Madrid earthquake

    USGS Publications Warehouse

    Hough, S.E.; Martin, S.

    2002-01-01

    The three principal New Madrid mainshocks of 1811-1812 were followed by extensive aftershock sequences that included numerous felt events. Although no instrumental data are available for either the mainshocks or the aftershocks, available historical accounts do provide information that can be used to estimate magnitudes and locations for the large events. In this article we investigate two of the largest aftershocks: one near dawn following the first mainshock on 16 December 1811, and one near midday on 17 December 1811. We reinterpret original felt reports to obtain a set of 48 and 20 modified Mercalli intensity values of the two aftershocks, respectively. For the dawn aftershock, we infer a Mw of approximately 7.0 based on a comparison of its intensities with those of the smallest New Madrid mainshock. Based on a detailed account that appears to describe near-field ground motions, we further propose a new fault rupture scenario for the dawn aftershock. We suggest that the aftershock had a thrust mechanism and occurred on a southeastern limb of the Reelfoot fault. For the 17 December 1811 aftershock, we infer a Mw of approximately 6.1 ?? 0.2. This value is determined using the method of Bakun et al. (2002), which is based on a new calibration of intensity versus distance for earthquakes in central and eastern North America. The location of this event is not well constrained, but the available accounts suggest an epicenter beyond the southern end of the New Madrid Seismic Zone.

  14. Substance Use Recovery Outcomes among a Cohort of Youth Participating in a Mobile-Based Texting Aftercare Pilot Program

    PubMed Central

    Gonzales, Rachel; Ang, Alfonso; Murphy, Debra A.; Glik, Deborah C.; Anglin, M. Douglas

    2014-01-01

    Project ESQYIR (Educating & Supporting inquisitive Youth in Recovery) is a pilot study examining the feasibility of a 12-week mobile-based aftercare intervention for youth (ages 12 to 24) transitioning out of community-based substance abuse treatment programs. From January 2012 through July 2013, a total of 80 youth were recruited from outpatient and residential treatment programs, geographically dispersed throughout Los Angeles County, California. Results revealed that youth who participated in the texting mobile pilot intervention were significantly less likely to relapse to their primary compared to the aftercare as usual control condition (OR = 0.52, p = 0.002) over time (from baseline throughout the 12-week aftercare pilot program to a 90-day follow-up). Participants in the texting aftercare pilot program also reported significantly less substance use problem severity (β = −0.46, p = .03) and were more likely to participate in extracurricular recovery behaviors (β = 1.63, p = .03) compared to participants in the standard aftercare group. Collectively, findings from this pilot aftercare study suggest that mobile texting could provide a feasible way to engage youth in recovery after substance abuse treatment to aid with reducing relapse and promoting lifestyle behavior change. PMID:24629885

  15. Role of static stress diffusion in the spatiotemporal organization of aftershocks.

    PubMed

    Lippiello, E; de Arcangelis, L; Godano, C

    2009-07-17

    We investigate the spatial distribution of aftershocks, and we find that aftershock linear density exhibits a maximum that depends on the main shock magnitude, followed by a power law decay. The exponent controlling the asymptotic decay and the fractal dimensionality of epicenters clearly indicate triggering by static stress. The nonmonotonic behavior of the linear density and its dependence on the main shock magnitude can be interpreted in terms of diffusion of static stress. This is supported by the power law growth with exponent H approximately 0.5 of the average main-aftershock distance. Implementing static stress diffusion within a stochastic model for aftershock occurrence, we are able to reproduce aftershock linear density spatial decay, its dependence on the main shock magnitude, and its evolution in time.

  16. Mobile Learning in Teacher Education: Insight from Four Programs That Embraced Change

    ERIC Educational Resources Information Center

    Burke, Diane M.; Foulger, Teresa S.

    2014-01-01

    Access to and use of mobile technologies are growing exponentially. The authors of this study identified four schools of education in the United States that self-identified as having a fully implemented curriculum for teachers on mobile technology use in PK-12 classrooms. In-depth interviews were conducted with a representative from each…

  17. The Mobile Reference Service: a case study of an onsite reference service program at the school of public health*

    PubMed Central

    Tao, Donghua; McCarthy, Patrick G.; Krieger, Mary M.; Webb, Annie B.

    2009-01-01

    The School of Public Health at Saint Louis University is located at a greater distance from the library than other programs on the main medical center campus. Physical distance diminishes the ease of access to direct reference services for public health users. To bridge the gap, the library developed the Mobile Reference Service to deliver onsite information assistance with regular office hours each week. Between September 2006 and April 2007, a total of 57 in-depth reference transactions took place over 25 weeks, averaging 2 transactions per week in a 2-hour period. Overall reference transactions from public health users went up 28%, while liaison contacts with public health users doubled compared to the same period the year before. The Mobile Reference Service program has improved library support for research and scholarship, cultivated and strengthened liaison relationships, and enhanced marketing and delivery of library resources and services to the Saint Louis University School of Public Health. PMID:19159004

  18. Static stress triggering explains the empirical aftershock distance decay

    NASA Astrophysics Data System (ADS)

    Hainzl, Sebastian; Moradpour, Javad; Davidsen, Jörn

    2014-12-01

    The shape of the spatial aftershock decay is sensitive to the triggering mechanism and thus particularly useful for discriminating between static and dynamic stress triggering. For California seismicity, it has been recently recognized that its form is more complicated than typically assumed consisting of three different regimes with transitions at the scale of the rupture length and the thickness of the crust. The intermediate distance range is characterized by a relative small decay exponent of 1.35 previously declared to relate to dynamic stress triggering. We perform comprehensive simulations of a simple clock-advance model, in which the number of aftershocks is just proportional to the Coulomb-stress change, to test whether the empirical result can be explained by static stress triggering. Similarly to the observations, the results show three scaling regimes. For simulations adapted to the depths and focal mechanisms observed in California, we find a remarkable agreement with the observation over the whole distance range for a fault distribution with fractal dimension of 1.8, which is shown to be in good agreement with an independent analysis of California seismicity.

  19. Temperature-programmed electrospray-differential mobility analysis for characterization of ligated nanoparticles in complex media.

    PubMed

    Tsai, De-Hao; DelRio, Frank W; Pettibone, John M; Lin, Pin-Ann; Tan, Jiaojie; Zachariah, Michael R; Hackley, Vincent A

    2013-09-10

    An electrospray-differential mobility analyzer (ES-DMA) was operated with an aerosol flow-mode, temperature-programmed approach to enhance its ability to characterize the particle size distributions (PSDs) of nanoscale particles (NPs) in the presence of adsorbed and free ligands. Titanium dioxide NPs (TiO2-NPs) stabilized by citric acid (CA) or bovine serum albumin (BSA) were utilized as representative systems. Transmission electron microscopy (TEM) and inductively coupled plasma mass spectrometry were used to provide visual information and elemental-based PSDs, respectively. Results show that the interference resulting from electrospray-dried nonvolatile salt residual nanoscale particles (S-NPs) could be effectively reduced using the thermal treatment process: PSDs were accurately measured at temperatures above 200 °C for CA-stabilized TiO2-NPs and above 400 °C for BSA-stabilized TiO2-NPs. Moreover, TEM confirmed the volumetric shrinkage of S-NPs due to thermal treatment and also showed that the primary structure of TiO2-NPs was relatively stable over the temperature range studied (i.e., below 700 °C). Conversely, the shape factor for TiO2-NPs decreased after treatment above 500 °C, possibly due to a change in the secondary (aggregate) structure. S-NPs from BSA-stabilized TiO2-NPs exhibited higher global activation energies toward induced volumetric shrinkage than those of CA-stabilized TiO2-NPs, suggesting that activation energy is dependent on ligand size. This prototype study demonstrates the efficacy of using ES-DMA coupled with thermal treatment for characterizing the physical state of NPs, even in a complex medium (e.g., containing plasma proteins) and in the presence of particle agglomerates induced by interaction with binding ligands.

  20. A Group-Based Mobile Application to Increase Adherence in Exercise and Nutrition Programs: A Factorial Design Feasibility Study

    PubMed Central

    Venkatakrishnan, Anusha; Youngblood, Gregory Michael; Ram, Ashwin; Pirolli, Peter

    2016-01-01

    Background Novel methods of promoting self-monitoring and social support are needed to ensure long-term maintenance of behavior change. In this paper, we directly investigate the effects of group support in an exercise and nutrition program delivered by an mHealth application called Fittle. Objective Our first specific study aim was to explore whether social support improved adherence in wellness programs. Our second specific study aim was to assess whether media types (ePaper vs mobile) were associated with different levels of compliance and adherence to wellness programs. The third aim was to assess whether the use of an mHealth application led to positive changes to participants’ eating behavior, physical activity, and stress level, compared to traditional paper-based programs. Methods A 2 × 2 (eg, Media: Mobile vs ePaper × Group Type: Team vs Solo) factorial design feasibility study was conducted. A sample of 124 volunteers who were interested in improving eating behavior, increasing physical activity, or reducing stress participated in this study. The study duration was 8 weeks. All groups were self-directed with no ongoing human input from the research team. Results Participants in ePaper conditions had higher attrition rates compared to participants in Mobile conditions, χ3 2=9.96, P=.02 (N=124). Participants in Mobile conditions reported their compliance with a much higher frequency closer to the time of challenge activity completion (2-sample Kolmogorov-Smirnov test comparing distributions was highly significant—KS=0.33, P<.001 [N=63]). Participants in ePaper conditions had a much higher frequency of guessing while reporting as compared with those in Mobile conditions—χ1 2=25.25, P<.001 (N=63). Together, these findings suggest that the mobile app allowed a more accurate method to report and track health behaviors over a longer period than traditional ePaper-based diaries or log books. There was a significant difference in the overall compliance

  1. The Use of Explosion Aftershock Probabilities for Planning and Deployment of Seismic Aftershock Monitoring System for an On-site Inspection

    NASA Astrophysics Data System (ADS)

    Labak, P.; Ford, S. R.; Sweeney, J. J.; Smith, A. T.; Spivak, A.

    2011-12-01

    One of four elements of CTBT verification regime is On-site inspection (OSI). Since the sole purpose of an OSI shall be to clarify whether a nuclear weapon test explosion or any other nuclear explosion has been carried out, inspection activities can be conducted and techniques used in order to collect facts to support findings provided in inspection reports. Passive seismological monitoring, realized by the seismic aftershock monitoring (SAMS) is one of the treaty allowed techniques during an OSI. Effective planning and deployment of SAMS during the early stages of an OSI is required due to the nature of possible events recorded and due to the treaty related constrains on size of inspection area, size of inspection team and length of an inspection. A method, which may help in planning the SAMS deployment is presented. An estimate of aftershock activity due to a theoretical underground nuclear explosion is produced using a simple aftershock rate model (Ford and Walter, 2010). The model is developed with data from the Nevada Test Site and Semipalatinsk Test Site, which we take to represent soft- and hard-rock testing environments, respectively. Estimates of expected magnitude and number of aftershocks are calculated using the models for different testing and inspection scenarios. These estimates can help to plan the SAMS deployment for an OSI by giving a probabilistic assessment of potential aftershocks in the Inspection Area (IA). The aftershock assessment combined with an estimate of the background seismicity in the IA and an empirically-derived map of threshold magnitude for the SAMS network could aid the OSI team in reporting. We tested the hard-rock model to a scenario similar to the 2008 Integrated Field Exercise 2008 deployment in Kazakhstan and produce an estimate of possible recorded aftershock activity.

  2. The (Un)Productivity of the 2014 M6.0 South Napa Aftershock Sequence

    NASA Astrophysics Data System (ADS)

    Llenos, A. L.

    2014-12-01

    The M6.0 South Napa mainshock produced fewer aftershocks than expected for a California earthquake of its magnitude, which became apparent a few days into the sequence. In the first 4.5 days, only 59 M≥1.8 aftershocks had occurred, the largest of which was a M3.9 that happened a little over two days after the mainshock. In contrast, during the same time period the 2004 M6.0 Parkfield earthquake had over 220 M≥1.8 aftershocks, 6 of which were M≥4. Here I investigate the aftershock productivity and other sequence statistics of the South Napa sequence and compare it with other M~6 California mainshock-aftershock sequences. By focusing on similar size events, they have similar finite extents within the seismotectonic environment. While the productivities of these sequences vary quite a bit, the b-values of the magnitude-frequency distributions all fall in the 0.6-0.8 range for the northern California sequences, slightly lower than the b-value of ~1 typical of southern California seismicity. Despite the relatively low productivity of the South Napa sequence, I show that the Epidemic-Type Aftershock Sequence (ETAS) model (Ogata, JASA, 1988) describes the sequence well and investigate whether the ETAS model parameters suggest that low-productivity sequences are typical for the region. I also explore how quickly after a mainshock these types of models can capture the low productivity of the sequence. The productivity of a sequence is a critical parameter in determining the aftershock probabilities reported in the days following the mainshock. Therefore, the sooner an accurate representation of the aftershock productivity can be obtained, the sooner more accurate aftershock probability reports can be produced.

  3. Aftershocks illuninate the 2011 Mineral, Virginia, earthquake causative fault zone and nearby active faults

    USGS Publications Warehouse

    Horton, Jr., J. Wright; Shah, Anjana K.; McNamara, Daniel E.; Snyder, Stephen L.; Carter, Aina M

    2015-01-01

    Deployment of temporary seismic stations after the 2011 Mineral, Virginia (USA), earthquake produced a well-recorded aftershock sequence. The majority of aftershocks are in a tabular cluster that delineates the previously unknown Quail fault zone. Quail fault zone aftershocks range from ~3 to 8 km in depth and are in a 1-km-thick zone striking ~036° and dipping ~50°SE, consistent with a 028°, 50°SE main-shock nodal plane having mostly reverse slip. This cluster extends ~10 km along strike. The Quail fault zone projects to the surface in gneiss of the Ordovician Chopawamsic Formation just southeast of the Ordovician–Silurian Ellisville Granodiorite pluton tail. The following three clusters of shallow (<3 km) aftershocks illuminate other faults. (1) An elongate cluster of early aftershocks, ~10 km east of the Quail fault zone, extends 8 km from Fredericks Hall, strikes ~035°–039°, and appears to be roughly vertical. The Fredericks Hall fault may be a strand or splay of the older Lakeside fault zone, which to the south spans a width of several kilometers. (2) A cluster of later aftershocks ~3 km northeast of Cuckoo delineates a fault near the eastern contact of the Ordovician Quantico Formation. (3) An elongate cluster of late aftershocks ~1 km northwest of the Quail fault zone aftershock cluster delineates the northwest fault (described herein), which is temporally distinct, dips more steeply, and has a more northeastward strike. Some aftershock-illuminated faults coincide with preexisting units or structures evident from radiometric anomalies, suggesting tectonic inheritance or reactivation.

  4. Statistical estimation of the duration of aftershock sequences

    NASA Astrophysics Data System (ADS)

    Hainzl, S.; Christophersen, A.; Rhoades, D.; Harte, D.

    2016-05-01

    It is well known that large earthquakes generally trigger aftershock sequences. However, the duration of those sequences is unclear due to the gradual power-law decay with time. The triggering time is assumed to be infinite in the epidemic type aftershock sequence (ETAS) model, a widely used statistical model to describe clustering phenomena in observed earthquake catalogues. This assumption leads to the constraint that the power-law exponent p of the Omori-Utsu decay has to be larger than one to avoid supercritical conditions with accelerating seismic activity on long timescales. In contrast, seismicity models based on rate- and state-dependent friction observed in laboratory experiments predict p ≤ 1 and a finite triggering time scaling inversely to the tectonic stressing rate. To investigate this conflict, we analyse an ETAS model with finite triggering times, which allow smaller values of p. We use synthetic earthquake sequences to show that the assumption of infinite triggering times can lead to a significant bias in the maximum likelihood estimates of the ETAS parameters. Furthermore, it is shown that the triggering time can be reasonably estimated using real earthquake catalogue data, although the uncertainties are large. The analysis of real earthquake catalogues indicates mainly finite triggering times in the order of 100 days to 10 years with a weak negative correlation to the background rate, in agreement with expectations of the rate- and state-friction model. The triggering time is not the same as the apparent duration, which is the time period in which aftershocks dominate the seismicity. The apparent duration is shown to be strongly dependent on the mainshock magnitude and the level of background activity. It can be much shorter than the triggering time. Finally, we perform forward simulations to estimate the effective forecasting period, which is the time period following a mainshock, in which ETAS simulations can improve rate estimates after the

  5. Recent Experiences in Aftershock Hazard Modelling in New Zealand

    NASA Astrophysics Data System (ADS)

    Gerstenberger, M.; Rhoades, D. A.; McVerry, G.; Christophersen, A.; Bannister, S. C.; Fry, B.; Potter, S.

    2014-12-01

    The occurrence of several sequences of earthquakes in New Zealand in the last few years has meant that GNS Science has gained significant recent experience in aftershock hazard and forecasting. First was the Canterbury sequence of events which began in 2010 and included the destructive Christchurch earthquake of February, 2011. This sequence is occurring in what was a moderate-to-low hazard region of the National Seismic Hazard Model (NSHM): the model on which the building design standards are based. With the expectation that the sequence would produce a 50-year hazard estimate in exceedance of the existing building standard, we developed a time-dependent model that combined short-term (STEP & ETAS) and longer-term (EEPAS) clustering with time-independent models. This forecast was combined with the NSHM to produce a forecast of the hazard for the next 50 years. This has been used to revise building design standards for the region and has contributed to planning of the rebuilding of Christchurch in multiple aspects. An important contribution to this model comes from the inclusion of EEPAS, which allows for clustering on the scale of decades. EEPAS is based on three empirical regressions that relate the magnitudes, times of occurrence, and locations of major earthquakes to regional precursory scale increases in the magnitude and rate of occurrence of minor earthquakes. A second important contribution comes from the long-term rate to which seismicity is expected to return in 50-years. With little seismicity in the region in historical times, a controlling factor in the rate is whether-or-not it is based on a declustered catalog. This epistemic uncertainty in the model was allowed for by using forecasts from both declustered and non-declustered catalogs. With two additional moderate sequences in the capital region of New Zealand in the last year, we have continued to refine our forecasting techniques, including the use of potential scenarios based on the aftershock

  6. Operational Demands of AAC Mobile Technology Applications on Programming Vocabulary and Engagement During Professional and Child Interactions.

    PubMed

    Caron, Jessica; Light, Janice; Drager, Kathryn

    2016-01-01

    Typically, the vocabulary in augmentative and alternative communication (AAC) technologies is pre-programmed by manufacturers or by parents and professionals outside of daily interactions. Because vocabulary needs are difficult to predict, young children who use aided AAC often do not have access to vocabulary concepts as the need and interest arises in their daily interactions, limiting their vocabulary acquisition and use. Ideally, parents and professionals would be able to add vocabulary to AAC technologies "just-in-time" as required during daily interactions. This study compared the effects of two AAC applications for mobile technologies: GoTalk Now (which required more programming steps) and EasyVSD (which required fewer programming steps) on the number of visual scene displays (VSDs) and hotspots created in 10-min interactions between eight professionals and preschool-aged children with typical development. The results indicated that, although all of the professionals were able to create VSDs and add vocabulary during interactions with the children, they created more VSDs and hotspots with the app with fewer programming steps than with the one with more steps, and child engagement and programming participation levels were high with both apps, but higher levels for both variables were observed with the app with fewer programming steps than with the one with more steps. These results suggest that apps with fewer programming steps may reduce operational demands and better support professionals to (a) respond to the child's input, (b) use just-in-time programming during interactions,

  7. Evidence that Stress Amplitude Does Not Affect the Temporal Distribution of Aftershocks

    NASA Astrophysics Data System (ADS)

    Felzer, K. R.

    2005-12-01

    Most physical aftershock triggering models, including the rate and state friction model of Dieterich (1994), the stress corrosion model (see discussion in Gomberg, 2001) and other accelerating failure models predict that larger stress changes on a fault will lead to an aftershocks that happens more quickly (larger clock advance), all else equal. Thus as stress change amplitude decreases with distance from the mainshock, there is an expected shift in the aftershock distribution toward longer time delays. This effect was formalized by Dieterich (1994) as an increase of the modified Omori Law c value (N(t) = A/(t+c)p where t = time, N(t) = aftershock rate, and A, p, and c are constants). Jones and Hauksson (1998), however, found no change in c value with distance after the 1992 MW 7.3 Landers earthquake. The assumption that the aftershock temporal distribution is independent of distance is also made in ETAS (Epidemic Triggering Aftershock Sequence) aftershock simulations (Ogata, 1998; Helmstetter, 2002) without adverse affect on fitting real data. Here we verify the independence of stress change and aftershock temporal distribution using a data set of 33 M 5-6 mainshocks from throughout California. These mainshocks are large enough to produce a significant number of aftershocks in the near and far field, but small enough to be frequent and thus provide good statistical sampling. Our data verifies that the temporal distribution of aftershocks is independent of stress change amplitude. We suggest that the most likely explanation for this observation is that the timing of each fault that participates in an aftershock sequence is independent of the amplitude of the stress that triggers it. In this case aftershock decay with distance from the mainshock cannot be caused by smaller clock advances on lesser-stressed faults, as in the Dieterich (1994) model, but rather by a stress amplitude dependent probability that a fault will be clock advanced at all. In future work we

  8. Felt reports and intensity assignments for aftershocks and triggered events of the great 1906 California earthquake

    USGS Publications Warehouse

    Meltzner, Aron J.; Wald, David J.

    2002-01-01

    The San Andreas fault is the longest fault in California and one of the longest strikeslip faults in the world, yet little is known about the aftershocks following the most recent great event on the San Andreas, the M 7.8 San Francisco earthquake, on 18 April 1906. This open-file report is a compilation of first-hand accounts (felt reports) describing aftershocks and triggered events of the 1906 earthquake, for the first twenty months of the aftershock sequence (through December 1907). The report includes a chronological catalog. For the larger events, Modified Mercalli intensities (MMIs) have been assigned based on the descriptions judged to be the most reliable.

  9. A Quantitative Test for the Spatial Relationship Between Aftershock Distributions and Mainshock Rupture Properties

    NASA Astrophysics Data System (ADS)

    Woessner, J.; Ripperger, J.; Mai, M. P.; Wiemer, S.

    2004-12-01

    Correlating the properties of the mainshock rupture with the location of corresponding aftershocks may provide insight into the relationship between mainshock-induced static stress changes and aftershock occurrence. In this study, we develop a rigorous statistical test to quantify the spatial pattern of aftershock locations with the corresponding distributions of coseismic slip and stress-drop. Well-located aftershock hypocenters are projected onto the mainshock fault plane and coseismic slip and stress drop values are interpolated to their respective location. The null hypothesis H0 for the applied test statistic is: Aftershock hypocenters are randomly distributed on the mainshock fault plane and are not correlated with mainshock properties. Because we want to maintain spatial earthquake clustering as one of the important observed features of seismicity, we synthesize slip distributions using a random spatial field model from which we then compute the respective stress-drop distributions. For each simulation of earthquake slip, we compute the test statistic for the slip and stress-drop distribution, testing whether or not an apparent correlation between mainshock properties and aftershock locations exists. Uncertainties in the aftershock locations are accounted for by simulating a thousand catalogues for which we randomize the location of the aftershocks within their given location error bounds. We then determine the number of aftershocks in low-slip or negative stress-drop regions for simulated slip distributions, and compare those to the measurements obtained for finite-source slip inversions. We apply the test to crustal earthquakes in California and Japan. If possible, we use different source models and earthquake catalogues with varying accuracy to investigate the dependence of the test results on, for example, the location uncertainties of aftershocks. Contrary to the visual impression, we find that for some strike-slip earthquakes or segments of the

  10. Text2Quit: results from a pilot test of a personalized, interactive mobile health smoking cessation program.

    PubMed

    Abroms, Lorien C; Ahuja, Meenakshi; Kodl, Yvonne; Thaweethai, Lalida; Sims, Justin; Winickoff, Jonathan P; Windsor, Richard A

    2012-01-01

    Text messaging programs on mobile phones have shown some promise in helping people quit smoking. Text2Quit is an automated, personalized, and interactive mobile health program that sends text messages and e-mails timed around a participant's quit date over the course of 3 months. The text messages include pre- and post-quit educational messages, peer ex-smoker messages, medication reminders and relapse messages, and multiple opportunities for interaction. Study participants were university students (N = 23) enrolled in the Text2Quit program. Participants were surveyed at baseline and at 2 and 4 weeks after enrollment. The majority of participants agreed that they liked the program at 2 and 4 weeks after enrollment (90.5% and 82.3%, respectively). Support for text messages was found to be moderate and higher than that of the e-mail and web components. Of participants, 75% reported reading most or all of the texts. On average, users made 11.8 responses to the texts over a 4-week period, although responses declined after the quit date. The interactive feature for tracking cigarettes was the most used interactive feature, followed by the craving trivia game. This pilot test provides some support for the Text2Quit program. A future iteration of the program will include additional tracking features in both the pre-quit and post-quit protocols and an easier entry into the not-quit protocol. Future studies are recommended that identify the value of the interactive and personalized features that characterize this program.

  11. Accessing best practice resources using mobile technology in an undergraduate nursing program: a feasibility study.

    PubMed

    Mann, Elizabeth G; Medves, Jennifer; Vandenkerkhof, Elizabeth G

    2015-03-01

    Mobile technology presents new opportunities for nursing education and ultimately the provision of nursing care. The aim of this study was to explore the utility of mobile technology in undergraduate nursing education. In this evaluation study, undergraduate nursing students were provided with iPod Touch devices containing best practice guidelines. Computer self-efficacy was assessed, and the Theory of Planned Behavior was used to identify potential predictors of the use of mobile technology. Questionnaires were completed at baseline (n = 33) and postimplementation (n = 23). Feedback on feasibility issues was recorded throughout the study period. Students generally found the devices useful, and few technical problems were identified; however, lack of skill in using the devices and lack of support from staff in the clinical setting were commonly identified issues. Self-efficacy scores were high throughout the study. Attitudes, perceptions of the desirability of use, perceived personal control over use, and intentions of using the device were lower postimplementation than at baseline. Attitude toward the technology predicted intention to use the device after graduation. Mobile technology may promote evidence-informed practice; however, supporting students' acquisition of related skills may optimize use. Successful integration of mobile technology into practice requires attention to factors that affect student attitudes. PMID:25636042

  12. Accessing best practice resources using mobile technology in an undergraduate nursing program: a feasibility study.

    PubMed

    Mann, Elizabeth G; Medves, Jennifer; Vandenkerkhof, Elizabeth G

    2015-03-01

    Mobile technology presents new opportunities for nursing education and ultimately the provision of nursing care. The aim of this study was to explore the utility of mobile technology in undergraduate nursing education. In this evaluation study, undergraduate nursing students were provided with iPod Touch devices containing best practice guidelines. Computer self-efficacy was assessed, and the Theory of Planned Behavior was used to identify potential predictors of the use of mobile technology. Questionnaires were completed at baseline (n = 33) and postimplementation (n = 23). Feedback on feasibility issues was recorded throughout the study period. Students generally found the devices useful, and few technical problems were identified; however, lack of skill in using the devices and lack of support from staff in the clinical setting were commonly identified issues. Self-efficacy scores were high throughout the study. Attitudes, perceptions of the desirability of use, perceived personal control over use, and intentions of using the device were lower postimplementation than at baseline. Attitude toward the technology predicted intention to use the device after graduation. Mobile technology may promote evidence-informed practice; however, supporting students' acquisition of related skills may optimize use. Successful integration of mobile technology into practice requires attention to factors that affect student attitudes.

  13. A random effects epidemic-type aftershock sequence model

    PubMed Central

    Lin, Feng-Chang

    2013-01-01

    We consider an extension of the temporal epidemic-type aftershock sequence (ETAS) model with random effects as a special case of a well-known doubly stochastic self-exciting point process. The new model arises from a deterministic function that is randomly scaled by a nonnegative random variable, which is unobservable but assumed to follow either positive stable or one-parameter gamma distribution with unit mean. Both random effects models are of interest although the one-parameter gamma random effects model is more popular when modeling associated survival times. Our estimation is based on the maximum likelihood approach with marginalized intensity. The methods are shown to perform well in simulation experiments. When applied to an earthquake sequence on the east coast of Taiwan, the extended model with positive stable random effects provides a better model fit, compared to the original ETAS model and the extended model with one-parameter gamma random effects. PMID:24039322

  14. A random effects epidemic-type aftershock sequence model.

    PubMed

    Lin, Feng-Chang

    2011-04-01

    We consider an extension of the temporal epidemic-type aftershock sequence (ETAS) model with random effects as a special case of a well-known doubly stochastic self-exciting point process. The new model arises from a deterministic function that is randomly scaled by a nonnegative random variable, which is unobservable but assumed to follow either positive stable or one-parameter gamma distribution with unit mean. Both random effects models are of interest although the one-parameter gamma random effects model is more popular when modeling associated survival times. Our estimation is based on the maximum likelihood approach with marginalized intensity. The methods are shown to perform well in simulation experiments. When applied to an earthquake sequence on the east coast of Taiwan, the extended model with positive stable random effects provides a better model fit, compared to the original ETAS model and the extended model with one-parameter gamma random effects.

  15. Maximal radius of the aftershock zone in earthquake networks

    NASA Astrophysics Data System (ADS)

    Mezentsev, A. Yu.; Hayakawa, M.

    2009-09-01

    In this paper, several seismoactive regions were investigated (Japan, Southern California and two tectonically distinct Japanese subregions) and structural seismic constants were estimated for each region. Using the method for seismic clustering detection proposed by Baiesi and Paczuski [M. Baiesi, M. Paczuski, Phys. Rev. E 69 (2004) 066106; M. Baiesi, M. Paczuski, Nonlin. Proc. Geophys. (2005) 1607-7946], we obtained the equation of the aftershock zone (AZ). It was shown that the consideration of a finite velocity of seismic signal leads to the natural appearance of maximal possible radius of the AZ. We obtained the equation of maximal radius of the AZ as a function of the magnitude of the main event and estimated its values for each region.

  16. A New Hybrid STEP/Coulomb model for Aftershock Forecasting

    NASA Astrophysics Data System (ADS)

    Steacy, S.; Jimenez, A.; Gerstenberger, M.

    2014-12-01

    Aftershock forecasting models tend to fall into two classes - purely statistical approaches based on clustering, b-value, and the Omori-Utsu law; and Coulomb rate-state models which relate the forecast increase in rate to the magnitude of the Coulomb stress change. Recently, hybrid models combining physical and statistical forecasts have begun to be developed, for example by Bach and Hainzl (2012) and Steacy et al. (2013). The latter approach combined Coulomb stress patterns with the STEP (short-term earthquake probability) model by redistributing expected rate from areas with decreased stress to regions where the stress had increased. The chosen 'Coulomb Redistribution Parameter' (CRP) was 0.93, based on California earthquakes, which meant that 93% of the total rate was expected to occur where the stress had increased. The model was tested against the Canterbury sequence and the main result was that the new model performed at least as well as, and often better than, STEP when tested against retrospective data but that STEP was generally better in pseudo-prospective tests that involved data actually available within the first 10 days of each event of interest. The authors suggested that the major reason for this discrepancy was uncertainty in the slip models and, particularly, in the geometries of the faults involved in each complex major event. Here we develop a variant of the STEP/Coulomb model in which the CRP varies based on the percentage of aftershocks that occur in the positively stressed areas during the forecast learning period. We find that this variant significantly outperforms both STEP and the previous hybrid model in almost all cases, even when the input Coulomb model is quite poor. Our results suggest that this approach might be more useful than Coulomb rate-state when the underlying slip model is not well constrained due to the dependence of that method on the magnitude of the Coulomb stress change.

  17. Aftershock seismicity of the 2010 Maule Mw=8.8 Chile, earthquake: Correlation between co-seismic slip models and aftershock distribution?

    USGS Publications Warehouse

    Rietbrock, A.; Ryder, I.; Hayes, G.; Haberland, C.; Comte, D.; Roecker, S.

    2012-01-01

    The 27 February 2010 Maule, Chile (Mw=8.8) earthquake is one of the best instrumentally observed subduction zone megathrust events. Here we present locations, magnitudes and cumulative equivalent moment of the first -2 months of aftershocks, recorded on a temporary network deployed within 2 weeks of the occurrence of the mainshock. Using automatically-determined onset times and a back projection approach for event association, we are able to detect over 30,000 events in the time period analyzed. To further increase the location accuracy, we systematically searched for potential S-wave arrivals and events were located in a regional 2D velocity model. Additionally, we calculated regional moment tensors to gain insight into the deformation history of the aftershock sequence. We find that the aftershock seismicity is concentrated between 40 and 140 km distance from the trench over a depth range of 10 to 35 km. Focal mechanisms indicate a predominance of thrust faulting, with occasional normal faulting events. Increased activity is seen in the outer-rise region of the Nazca plate, predominantly in the northern part of the rupture area. Further down-dip, a second band of clustered seismicity, showing mainly thrust motion, is located at depths of 40–45 km. By comparing recent published mainshock source inversions with our aftershock distribution, we discriminate slip models based on the assumption that aftershocks occur in areas of rapid transition between high and low slip, surrounding high-slip regions of the mainshock.

  18. HerzMobil Tirol network: rationale for and design of a collaborative heart failure disease management program in Austria.

    PubMed

    Von der Heidt, Andreas; Ammenwerth, Elske; Bauer, Karl; Fetz, Bettina; Fluckinger, Thomas; Gassner, Andrea; Grander, Willhelm; Gritsch, Walter; Haffner, Immaculata; Henle-Talirz, Gudrun; Hoschek, Stefan; Huter, Stephan; Kastner, Peter; Krestan, Susanne; Kufner, Peter; Modre-Osprian, Robert; Noebl, Josef; Radi, Momen; Raffeiner, Clemens; Welte, Stefan; Wiseman, Andreas; Poelzl, Gerhard

    2014-11-01

    Heart failure (HF) is approaching epidemic proportions worldwide and is the leading cause of hospitalization in the elderly population. High rates of readmission contribute substantially to excessive health care costs and highlight the fragmented nature of care available to HF patients. Disease management programs (DMPs) have been implemented to improve health outcomes, patient satisfaction, and quality of life, and to reduce health care costs. Telemonitoring systems appear to be effective in the vulnerable phase after discharge from hospital to prevent early readmissions. DMPs that emphasize comprehensive patient education and guideline-adjusted therapy have shown great promise to result in beneficial long-term effects. It can be speculated that combining core elements of the aforementioned programs may substantially improve long-term cost-effectiveness of patient management.We introduce a collaborative post-discharge HF disease management program (HerzMobil Tirol network) that incorporates physician-controlled telemonitoring and nurse-led care in a multidisciplinary network approach.

  19. The Assessment of Physical and Program Accessibility for Students with Physical (Mobility) Disabilities.

    ERIC Educational Resources Information Center

    Peterson, Deana R.

    A checklist and instructions are presented for evaluating the level of accessibility to school buildings, grounds, curricula, technology, and extracurricular activities for students with physical (mobility) disabilities. Legislative mandates (including The Americans with Disabilities Act of 1990, and Individuals with Disabilities Education Act)…

  20. Virtual Environments for People Who Are Visually Impaired Integrated into an Orientation and Mobility Program

    ERIC Educational Resources Information Center

    Lahav, Orly; Schloerb, David W.; Srinivasan, Mandayam A.

    2015-01-01

    Introduction: The BlindAid, a virtual system developed for orientation and mobility (O&M) training of people who are blind or have low vision, allows interaction with different virtual components (structures and objects) via auditory and haptic feedback. This research examined if and how the BlindAid that was integrated within an O&M…

  1. The "Trainer in Your Pocket:" Mobile Phones within a Teacher Continuing Professional Development Program in Bangladesh

    ERIC Educational Resources Information Center

    Walsh, Christopher S.; Power, Tom; Khatoon, Masuda; Biswas, Sudeb Kumar; Paul, Ashok Kumar; Sarkar, Bikash Chandra; Griffiths, Malcolm

    2013-01-01

    Examples of mobile phones being used with teachers to provide continuing professional development (CPD) in emerging economies at scale are largely absent from the research literature. We outline English in Action's (EIA) model for providing 80,000 teachers with CPD to improve their communicative language teaching in Bangladesh over nine…

  2. 77 FR 46439 - Medicare Program; Prior Authorization for Power Mobility Device (PMD) Demonstration

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-03

    ... in 60-day and 30-day Federal Register notices that published on February 7, 2012 (77 FR 6124) and May 29, 2012 (77 FR 31616), respectively. The information collection requirements are approved under OMB... Mobility Device (PMD) Demonstration AGENCY: Centers for Medicare & Medicaid Services (CMS), HHS....

  3. Three Ingredients for Improved Global Aftershock Forecasts: Tectonic Region, Time-Dependent Catalog Incompleteness, and Inter-Sequence Variability

    NASA Astrophysics Data System (ADS)

    Page, M. T.; Hardebeck, J.; Felzer, K. R.; Michael, A. J.; van der Elst, N.

    2015-12-01

    Following a large earthquake, seismic hazard can be orders of magnitude higher than the long-term average as a result of aftershock triggering. Due to this heightened hazard, there is a demand from emergency managers and the public for rapid, authoritative, and reliable aftershock forecasts. In the past, USGS aftershock forecasts following large, global earthquakes have been released on an ad-hoc basis with inconsistent methods, and in some cases, aftershock parameters adapted from California. To remedy this, we are currently developing an automated aftershock product that will generate more accurate forecasts based on the Reasenberg and Jones (Science, 1989) method. To better capture spatial variations in aftershock productivity and decay, we estimate regional aftershock parameters for sequences within the Garcia et al. (BSSA, 2012) tectonic regions. We find that regional variations for mean aftershock productivity exceed a factor of 10. The Reasenberg and Jones method combines modified-Omori aftershock decay, Utsu productivity scaling, and the Gutenberg-Richter magnitude distribution. We additionally account for a time-dependent magnitude of completeness following large events in the catalog. We generalize the Helmstetter et al. (2005) equation for short-term aftershock incompleteness and solve for incompleteness levels in the global NEIC catalog following large mainshocks. In addition to estimating average sequence parameters within regions, we quantify the inter-sequence parameter variability. This allows for a more complete quantification of the forecast uncertainties and Bayesian updating of the forecast as sequence-specific information becomes available.

  4. Forecasting Aftershocks from Multiple Earthquakes: Lessons from the Mw=7.3 2015 Nepal Earthquake

    NASA Astrophysics Data System (ADS)

    Jiménez, Abigail; NicBhloscaidh, Mairéad; McCloskey, John

    2016-04-01

    The Omori decay of aftershocks is often perturbed by large secondary events which present particular, but not uncommon, challenges to aftershock forecasting. The Mw = 7.8, 25 April 2015, Gorkha, Nepal earthquake was followed on 12 May by the Mw = 7.3 Kodari earthquake, superimposed its own aftershocks on the Gorkha sequence, immediately invalidating forecasts made by single-mainshock forecasting methods. The complexity of the Gorkha rupture process, where the hypocentre and moment centroid were separated by some 75 km, provided an insurmountable challenge for other standard forecasting methods. Here, we report several modifications of existing algorithms, which were developed in response to the complexity of this sequence and which appear to provide a more general framework for the robust and dependable forecasting of aftershock probabilities. We suggest that these methods may be operationalised to provide a scientific underpinning for an evidence-based management system for post-earthquake crises.

  5. Aftershocks of the 2014 M6 South Napa Earthquake: Detection, Location, and Focal Mechanisms

    NASA Astrophysics Data System (ADS)

    Hardebeck, J.; Shelly, D. R.

    2014-12-01

    The aftershock sequence of the South Napa earthquake is notable both for its low productivity and for its geometric complexity. The aftershocks do not clearly define a fault plane consistent with the NNW-striking vertical plane implied by the mainshock moment tensor and the mapped surface rupture, but instead seem to delineate multiple secondary structures at depth. We investigate this unusual sequence by identifying additional aftershocks that do not appear in the network catalog, relocating the combined aftershock catalog using waveform cross-correlation arrival times and double-difference techniques, and determining focal mechanisms for individual events and event clusters. Additional aftershocks are detected by applying a matched filter approach to the continuous seismic data at nearby stations, with the catalog earthquakes serving as the waveform templates. In tandem with new event detections, we measure precise differential arrival times between events, which we then use in double-difference event location. We detect about 4 times as many well-located aftershocks as in the network catalog. We relocate the events using double-difference in both a 1D and a 3D velocity model. Most of the aftershocks occur between 8 and 11 km depth, similar depth to the mainshock hypocenter and deeper than most of the slip imaged seismically and geodetically. The aftershocks form a diffuse NNW-trending structure, primarily to the north of the mainshock hypocenter and on the west side of the main surface rupture. Within this diffuse trend there are clusters of aftershocks, some suggesting a N-S strike, and some that appear to dip to the east or west. Preliminary single-event and composite focal mechanisms also imply N-S striking strike-slip structures. The mainshock hypocenter and many of the aftershocks occur near the intersection of a sharply defined NE-dipping seismicity structure and the probable location of the West Napa fault, suggesting that stress is concentrated at a

  6. Anomalous power law distribution of total lifetimes of branching processes: Application to earthquake aftershock sequences

    SciTech Connect

    Saichev, A.; Sornette, D.

    2004-10-01

    We consider a general stochastic branching process, which is relevant to earthquakes, and study the distributions of global lifetimes of the branching processes. In the earthquake context, this amounts to the distribution of the total durations of aftershock sequences including aftershocks of arbitrary generation number. Our results extend previous results on the distribution of the total number of offspring (direct and indirect aftershocks in seismicity) and of the total number of generations before extinction. We consider a branching model of triggered seismicity, the epidemic-type aftershock sequence model, which assumes that each earthquake can trigger other earthquakes ('aftershocks'). An aftershock sequence results in this model from the cascade of aftershocks of each past earthquake. Due to the large fluctuations of the number of aftershocks triggered directly by any earthquake ('productivity' or 'fertility'), there is a large variability of the total number of aftershocks from one sequence to another, for the same mainshock magnitude. We study the regime where the distribution of fertilities {mu} is characterized by a power law {approx}1/{mu}{sup 1+{gamma}} and the bare Omori law for the memory of previous triggering mothers decays slowly as {approx}1/t{sup 1+{theta}}, with 0<{theta}<1 relevant for earthquakes. Using the tool of generating probability functions and a quasistatic approximation which is shown to be exact asymptotically for large durations, we show that the density distribution of total aftershock lifetimes scales as {approx}1/t{sup 1+{theta}}{sup sol{gamma}} when the average branching ratio is critical (n=1). The coefficient 1<{gamma}=b/{alpha}<2 quantifies the interplay between the exponent b{approx_equal}1 of the Gutenberg-Richter magnitude distribution {approx}10{sup -bm} and the increase {approx}10{sup {alpha}}{sup m} of the number of aftershocks with mainshock magnitude m (productivity), with 0.5<{alpha}<1. The renormalization of the

  7. Evidence for fluid-triggering underlying the year 2014 aftershock sequences in NW Bohemia

    NASA Astrophysics Data System (ADS)

    Hainzl, S.; Fischer, T.; Cermakova, H.; Bachura, M.; Vlcek, J.

    2015-12-01

    The West Bohemia/Vogtland region, central Europe, is a place of localized repeating swarm activity continuously monitored during the last two decades, allowing a detailed study of the driving mechanisms. Previous earthquake episodes where characterized by swarm-type activity with gradual onsets and decays which were not related to mainshocks. However, the latest activity in the year 2014 occurred exactly in the same location as previous swarm activity but consisted of three classical aftershock sequences triggered by a M4.4 event and two ~M3.5 events. The apparent system change from swarm-type to mainshock-aftershock characteristics can have important implications for the understanding of swarm and aftershock generation as well as for seismic hazard assessment in this region. Thus we have analyzed in detail the spatiotemporal aftershock sequence based on a relocated earthquake catalog. Our analysis shows that the largest mainshock occurred in a step-over region of the fault plane with increased Coulomb stress due to previous activity. Its rupture plane connecting both segments is significantly rotated compared to most aftershocks, which occurred in-plane. The aftershock characteristics are classical in the way that (i) the aftershocks are clearly triggered by the mainshock, (ii) the maximum magnitude of the aftershocks is approximately 1.2 units less than the mainshock magnitude (Bath law), and (iii) the decay can be well fitted by the Omori-Utsu law. However, the absolute number of aftershocks and the fitted c and p values of the Omori-Utsu decay are significantly larger than for typical sequences. The fit of the epidemic type aftershock sequence (ETAS) model reveals a time-dependent background activity which exponentially decays with time after the mainshock. Pore pressure simulations with an exponentially decreasing flow rate of the fluid source show a good agreement with the observed spatial migration front of the aftershocks extending approximately with log

  8. Anomalous power law distribution of total lifetimes of branching processes: application to earthquake aftershock sequences.

    PubMed

    Saichev, A; Sornette, D

    2004-10-01

    We consider a general stochastic branching process, which is relevant to earthquakes, and study the distributions of global lifetimes of the branching processes. In the earthquake context, this amounts to the distribution of the total durations of aftershock sequences including aftershocks of arbitrary generation number. Our results extend previous results on the distribution of the total number of offspring (direct and indirect aftershocks in seismicity) and of the total number of generations before extinction. We consider a branching model of triggered seismicity, the epidemic-type aftershock sequence model, which assumes that each earthquake can trigger other earthquakes ("aftershocks"). An aftershock sequence results in this model from the cascade of aftershocks of each past earthquake. Due to the large fluctuations of the number of aftershocks triggered directly by any earthquake ("productivity" or "fertility"), there is a large variability of the total number of aftershocks from one sequence to another, for the same mainshock magnitude. We study the regime where the distribution of fertilities mu is characterized by a power law approximately 1/ mu(1+gamma) and the bare Omori law for the memory of previous triggering mothers decays slowly as approximately 1/ t(1+theta;) , with 0aftershock lifetimes scales as approximately 1/ t(1+theta;/gamma) when the average branching ratio is critical (n=1) . The coefficient 1aftershocks with mainshock magnitude m (productivity), with 0.5

  9. Analysis of Mw 7.2 2014 Molucca Sea earthquake and its aftershocks

    NASA Astrophysics Data System (ADS)

    Shiddiqi, Hasbi Ash; Widiyantoro, Sri; Nugraha, Andri Dian; Ramdhan, Mohamad; Wiyono, Samsul Hadi; Wandono, Wandono

    2016-05-01

    A Mw 7.2 earthquake struck an area in the Molucca Sea region on November 15, 2014, and was followed by more than 300 aftershocks until the end of December 2014. This earthquake was the second largest event in the Molucca Sea during the last decade and was well recorded by local networks. Although the seismicity rate of the aftershocks was declining at the end of 2014, several significant earthquakes with magnitude (Mw) larger than five still occurred from January to May 2015 within the vicinity of the mainshock location. In this study, we investigated the earthquake process and its relation to the increasing seismicity in the Molucca Sea within six months after the earthquake. We utilized teleseismic double-difference hypocenter relocation method using local, regional, and teleseismic direct body-wave arrival times of 514 earthquakes from the time of mainshock occurrence to May 2015. Furthermore, we analyzed the focal mechanism solutions from the National Research Institute for Earth Science and Disaster Prevention (NIED), Japan. From our results, we observed that aftershocks propagated along the NNE-SSW direction within a 100 km fault segment length of the Mayu Ridge. The highest number of the aftershocks was located in the SSW direction of the main event. The aftershocks were terminated at around 60 km depth, which may represent the location of the top of the Molucca Sea Plate (MSP). Between January and May 2015, several significant earthquakes propagated westward and were extended to the Molucca Sea slab. From focal mechanism catalog, we found that the mainshock mechanism was reverse with strike 192o and dip 55o. While most of the large aftershock mechanisms were consistent with the main event, several aftershocks had reverse, oblique mechanisms. Stress inversion result from focal mechanism data revealed that the maximum stress direction was SE and was not perpendicular with fault direction. We suggest that the non-perpendicular maximum stress caused several

  10. Correlating Aftershock Hypocenters With On-fault Main Shock Properties: Introducing Non-standard Statistical Tests

    NASA Astrophysics Data System (ADS)

    Woessner, J.; Schorlemmer, D.; Wiemer, S.; Mai, P. M.

    2005-12-01

    Quantitatively correlating properties of finite-fault source models with hypocenters of aftershocks may provide new insight in the relationship between either slip or static stress change distributions and aftershock occurrence. We present advanced non-standard statistical test approaches to evaluate the test hypotheses (1) if aftershocks are preferentially located in areas of low slip and (2) if aftershocks are located in increased shear stress against the null hypothesis: aftershocks are located randomly on the fault plane. By using multiple test approaches, we investigate possible pitfalls and the information content of statistical testing. To perform the tests, we use earthquakes for which multiple finite-fault source models and earthquake catalogs of varying accuracy exist. The aftershock hypocenters are projected onto the main-shock rupture plane and uncertainties are accounted for by simulating hypocenter locations in the given error bounds. For the statistical tests, we retain the spatial clustering of earthquakes as the most important observed features of seismicity and synthesize random slip distributions with different approaches: first, using standard statistical methods that randomize the obtained finite-fault source model values and second, using a random spatial field model. We then determine the number of aftershocks in low-slip or increased shear-stress regions for simulated slip distributions, and compare those to the measurements obtained for finite-source slip inversions. We apply the tests to prominent earthquakes in California and Japan and find statistical significant evidence that aftershocks are preferentially located in low-slip regions. The tests, however, show a lower significance for the correlation with the shear-stress distribution, but are in general agreement with the expectations of the asperity model. Tests using the hypocenters of relocated catalogs show higher significances.

  11. Forecasting aftershock activity: 1. Adaptive estimates based on the Omori and Gutenberg-Richter laws

    NASA Astrophysics Data System (ADS)

    Baranov, S. V.; Shebalin, P. N.

    2016-05-01

    The method for forecasting the intensity of the aftershock processes after strong earthquakes in different magnitude intervals is considered. The method is based on the joint use of the time model of the aftershock process and the Gutenberg-Richter law. The time model serves for estimating the intensity of the aftershock flow with a magnitude larger than or equal to the magnitude of completeness. The Gutenberg-Richter law is used for magnitude scaling. The suggested approach implements successive refinement of the parameters of both components of the method, which is the main novelty distinguishing it from the previous ones. This approach, to a significant extent, takes into account the variations in the parameters of the frequency-magnitude distribution, which often show themselves by the decreasing fraction of stronger aftershocks with time. Testing the method on eight aftershock sequences in the regions with different patterns of seismicity demonstrates the high probability of successful forecasts. The suggested technique can be employed in seismological monitoring centers for forecasting the aftershock activity of a strong earthquake based on the results of operational processing.

  12. An Explosion Aftershock Model with Application to On-Site Inspection

    NASA Astrophysics Data System (ADS)

    Ford, Sean R.; Labak, Peter

    2016-01-01

    An estimate of aftershock activity due to a theoretical underground nuclear explosion is produced using an aftershock rate model. The model is developed with data from the Nevada National Security Site, formerly known as the Nevada Test Site, and the Semipalatinsk Test Site, which we take to represent soft-rock and hard-rock testing environments, respectively. Estimates of expected magnitude and number of aftershocks are calculated using the models for different testing and inspection scenarios. These estimates can help inform the Seismic Aftershock Monitoring System (SAMS) deployment in a potential Comprehensive Test Ban Treaty On-Site Inspection (OSI), by giving the OSI team a probabilistic assessment of potential aftershocks in the Inspection Area (IA). The aftershock assessment, combined with an estimate of the background seismicity in the IA and an empirically derived map of threshold magnitude for the SAMS network, could aid the OSI team in reporting. We apply the hard-rock model to a M5 event and combine it with the very sensitive detection threshold for OSI sensors to show that tens of events per day are expected up to a month after an explosion measured several kilometers away.

  13. A Post-Hospital Home Exercise Program Improved Mobility but Increased Falls in Older People: A Randomised Controlled Trial

    PubMed Central

    Sherrington, Catherine; Lord, Stephen R.; Vogler, Constance M.; Close, Jacqueline C. T.; Howard, Kirsten; Dean, Catherine M.; Heller, Gillian Z.; Clemson, Lindy; O'Rourke, Sandra D.; Ramsay, Elisabeth; Barraclough, Elizabeth; Herbert, Robert D.; Cumming, Robert G.

    2014-01-01

    Background Home exercise can prevent falls in the general older community but its impact in people recently discharged from hospital is not known. The study aimed to investigate the effects of a home-based exercise program on falls and mobility among people recently discharged from hospital. Methods and Findings This randomised controlled trial (ACTRN12607000563460) was conducted among 340 older people. Intervention group participants (n = 171) were asked to exercise at home for 15–20 minutes up to 6 times weekly for 12 months. The control group (n = 169) received usual care. Primary outcomes were rate of falls (assessed over 12 months using monthly calendars), performance-based mobility (Lower Extremity Summary Performance Score, range 0–3, at baseline and 12 months, assessor unaware of group allocation) and self-reported ease of mobility task performance (range 0–40, assessed with 12 monthly questionaries). Participants had an average age of 81.2 years (SD 8.0) and 70% had fallen in the past year. Complete primary outcome data were obtained for at least 92% of randomised participants. Participants in the intervention group reported more falls than the control group (177 falls versus 123 falls) during the 12-month study period and this difference was statistically significant (incidence rate ratio 1.43, 95% CI 1.07 to 1.93, p = 0.017). At 12-months, performance-based mobility had improved significantly more in the intervention group than in the control group (between-group difference adjusted for baseline performance 0.13, 95% CI 0.04 to 0.21, p = 0.004). Self-reported ease in undertaking mobility tasks over the 12-month period was not significantly different between the groups (0.49, 95% CI −0.91 to 1.90, p = 0.488). Conclusions An individualised home exercise prescription significantly improved performance-based mobility but significantly increased the rate of falls in older people recently discharged from hospital. Trial Registration

  14. A plerixafor-based strategy allows adequate hematopoietic stem cell collection in poor mobilizers: results from the Canadian Special Access Program.

    PubMed

    Sheppard, D; Bredeson, C; Huebsch, L; Allan, D; Tay, J

    2014-06-01

    Plerixafor effectively mobilizes hematopoietic stem cells (HSCs). However, most patients' cells are successfully collected using traditional strategies and there is limited cost-effectiveness data. The objectives of this study were to: (1) summarize the published reports of mobilization using a plerixafor-based strategy during compassionate access programs and (2) describe the Canadian experience with plerixafor during its availability by Health Canada's Special Access Program. A literature search identified reports of plerixafor-based mobilization during compassionate access programs. Overall, successful collection of at least 2 × 10(6) CD34+ cells/kg was achieved in ~75% of patients, and about two-thirds of patients went on to HSCT. A greater proportion of patients had successful collections when plerixafor was used in the upfront or preemptive settings. Plerixafor was made available by Health Canada's SAP from September 2008 to December 2010. In 96 of 132 (73%) patients, there was successful collection of at least 2 × 10(6) CD34+ cells/kg. Ninety-nine (75%) patients went on to receive an autologous transplant. Plerixafor-based mobilization is effective in perceived poor mobilizers. The optimal way to incorporate plerixafor into a mobilization strategy, however, remains to be determined. Centre-specific analysis of resource utilization may help to identify the most cost-effective way to implement various plerixafor-based mobilization strategies.

  15. Neurosurgery Education and Development program to treat hydrocephalus and to develop neurosurgery in Africa using mobile neuroendoscopic training.

    PubMed

    Piquer, José; Qureshi, Mubashir Mahmood; Young, Paul H; Dempsey, Robert J

    2015-06-01

    OBJECT A shortage of neurosurgeons and a lack of knowledge of neuroendoscopic management of hydrocephalus limits modern care in sub-Saharan Africa. Hence, a mobile teaching project for endoscopic third ventriculostomy (ETV) procedures and a subsequent program to develop neurosurgery as a permanent specialty in Kenya and Zanzibar were created and sponsored by the Neurosurgery Education and Development (NED) Foundation and the Foundation for International Education in Neurological Surgery. The objective of this work was to evaluate the results of surgical training and medical care in both projects from 2006 to 2013. METHODS Two portable neuroendoscopy systems were purchased and a total of 38 ETV workshops were organized in 21 hospitals in 7 different countries. Additionally, 49 medical expeditions were dispatched to the Coast General Hospital in Mombasa, Kenya, and to the Mnazi Moja Hospital in Zanzibar. RESULTS From the first project, a total of 376 infants with hydrocephalus received surgery. Six-month follow-up was achieved in 22%. In those who received follow-up, ETV efficacy was 51%. The best success rates were achieved with patients 1 year of age or older with aqueductal stenosis (73%). The main causes of hydrocephalus were infection (56%) and spina bifida (23%). The mobile education program interacted with 72 local surgeons and 122 nurses who were trained in ETV procedures. The second project involved 49 volunteer neurosurgeons who performed a total of 360 nonhydrocephalus neurosurgical operations since 2009. Furthermore, an agreement with the local government was signed to create the Mnazi Mmoja NED Institute in Zanzibar. CONCLUSIONS Mobile endoscopic treatment of hydrocephalus in East Africa results in reasonable success rates and has also led to major developments in medicine, particularly in the development of neurosurgery specialty care sites.

  16. Aftershock Records in the Kathmandu Valley of the 2015 Gorkha, Nepal, Earthquake

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    The devastating earthquake, named the Gorkha Earthquake, was followed by a series of aftershocks: more than 350 of them greater than M 4 and four aftershock greater than M 6. The rupture of main shock originating 80 km NW of capital Kathmandu propagated towards east. The ensuing aftershock activities are concentrated in the eastern part of the rupture area. The aftershock of Mw 6.6 occurred about half an hour later at epicentre near to that of the main shock. The other three large aftershocks however, were originated in the eastern extreme of the rupture zone. The aftershock of Mw 7.3 that occurred on 12th May 2015 brought about more damages to infrastructures already vulnerable due to the main shock. To understand the site effect of the Kathmandu valley structure, we installed continuous recording accelerometers in four different parts of the valley. Four stations were installed along a west-to-east profile of the valley at KTP (Kirtipur; hill top), TVU (Kirtipur; hill side), PTN (Patan) and THM (Thimi). The surface S-wave velocity of the KTP site was over 700 cm s-1, but for each of the other three sites it was less than 200 cm s-1. These velocities are consistent with the geological formations; KTP is above hard rock, and TVU, PTN and THM are over the lake sediment of the valley. It is normal for the amplitude of earthquake motion to be larger in areas lying above sedimentary soil than in areas above hard rock, and these motions can be amplified further by certain deep underground structures. To know deep underground structure using with aftershock records, we installed more four instruments in the Kathmandu basin after main shock. We analysed the strong-motion data of these five aftershocks recorded in the eight strong-motion accelerometers. The station of KTP is considered as reference site to compare the effect of sediments on the earthquake waves. The large aftershocks all have highest Peak Ground Velocity (PGV) at TVU and the station of KTP showed the least

  17. Stress history controls the spatial pattern of aftershocks: case studies from strike-slip earthquakes

    NASA Astrophysics Data System (ADS)

    Utkucu, Murat; Durmuş, Hatice; Nalbant, Süleyman

    2016-09-01

    Earthquake ruptures perturb stress within the surrounding crustal volume and as it is widely accepted now these stress perturbations strongly correlates with the following seismicity. Here we have documented five cases of the mainshock-aftershock sequences generated by the strike-slip faults from different tectonic environments of world in order to demonstrate that the stress changes resulting from large preceding earthquakes decades before effect spatial distribution of the aftershocks of the current mainshocks. The studied mainshock-aftershock sequences are the 15 October 1979 Imperial Valley earthquake (Mw = 6.4) in southern California, the 27 November 1979 Khuli-Boniabad (Mw = 7.1), the 10 May 1997 Qa'enat (Mw = 7.2) and the 31 March 2006 Silakhor (Mw = 6.1) earthquakes in Iran and the 13 March 1992 Erzincan earthquake (Mw = 6.7) in Turkey. In the literature, we have been able to find only these mainshocks that are mainly characterized by dense and strong aftershock activities along and beyond the one end of their ruptures while rare aftershock occurrences with relatively lower magnitude reported for the other end of their ruptures. It is shown that the stress changes resulted from earlier mainshock(s) that are close in both time and space might be the reason behind the observed aftershock patterns. The largest aftershocks of the mainshocks studied tend to occur inside the stress-increased lobes that were also stressed by the background earthquakes and not to occur inside the stress-increased lobes that fall into the stress shadow of the background earthquakes. We suggest that the stress shadows of the previous mainshocks may persist in the crust for decades to suppress aftershock distribution of the current mainshocks. Considering active researches about use of the Coulomb stress change maps as a practical tool to forecast spatial distribution of the upcoming aftershocks for earthquake risk mitigation purposes in near-real time, it is further suggested that

  18. High-resolution relocation and mechanism of aftershocks of the 2007 Tocopilla (Chile) earthquake

    NASA Astrophysics Data System (ADS)

    Fuenzalida, A.; Schurr, B.; Lancieri, M.; Sobiesiak, M.; Madariaga, R.

    2013-08-01

    We study the distribution of the aftershocks of Tocopilla Mw 7.7 earthquake of 2007 November 14 in northern Chile in detail. This earthquake broke the lower part of the seismogenic zone at the southern end of the Northern Chile gap, a region that had its last megathrust earthquake in 1877. The aftershocks of Tocopilla occurred in several steps: the first day they were located along the coast inside the co-seismic rupture zone. After the second day they extended ocean-wards near the Mejillones peninsula. Finally in December they concentrated in the South near the future rupture zone of the Michilla intermediate depth earthquake of 2007 December 16. The aftershock sequence was recorded by the permanent IPOC (Integrated Plate Boundary Observatory in Chile) network and the temporary task force network installed 2 weeks after the main event. A total of 1238 events were identified and the seismic arrival times were directly read from seismograms. Initially we located these events using a single event procedure and then we relocated them using the double-difference method and a cross-correlation technique to measure time differences for clusters of aftershocks. We tested a 1-D velocity model and a 2-D one that takes into account the presence of the subducted Nazca Plate. Relocation significantly reduced the width of the aftershock distribution: in the inland area, the plate interface imaged by the aftershocks is thinner than 2 km. The two velocity models give similar results for earthquakes under the coast and a larger difference for events closer to the trench. The surface imaged by the aftershocks had a length of 160 km. It extends from 30 to 50 km depth in the northern part of the rupture zone; and between 5 and 55 km depth near the Mejillones peninsula. We observed a change in the dip angle of the subduction interface from 18° to 24° at a depth of 30 km. We propose that this change in dip is closely associated with the upper limit of the rupture zone of the main

  19. Can We Forecast 1-Month Span Aftershock Activity from the First Day Data after the Main Shock?

    NASA Astrophysics Data System (ADS)

    Omi, T.; Ogata, Y.; Hirata, Y.; Aihara, K.

    2014-12-01

    A large earthquake triggers persistent aftershock activity in and near the focal region. Thus, intermediate term forecasting of aftershocks at its earlier stage is important for mitigating seismic risks. A main difficulty for the early forecasting is the substantial incompleteness of early aftershock data. To deal with such incomplete data, we have developed a statistical model of the incomplete data, enabling us to obtain the immediate estimate of the forecasting models from incomplete data [1, 2]. Another difficulty for the intermediate term forecasting is that we have to determine the parameter values of the forecasting models with high accuracy, because even a small bias in the parameter values can lead to a significant bias of the forecasting in intermediate term. However such accurate estimation is quite difficult at the early stage, especially using the early and incomplete data. Here we present a Bayesian forecasting method by using the epidemic-type aftershock sequence (ETAS) model. The Bayesian forecasting considers not only the best parameter values such as the maximum likelihood estimates or maximum a posteriori estimates but also the estimation uncertainty of the parameter values. By analyzing aftershock sequences in Japan, we show the forecasting performances of the intermediate-term aftershocks can be significantly improved by considering the estimation uncertainty of the ETAS model [3]. Furthermore, we discuss the impact of the modeling of the magnitude frequency distribution of detected aftershocks within a day span on the forecasting of large aftershocks. [1] T. Omi, Y. Ogata, Y. Hirata and K. Aihara, "Forecasting large aftershocks within one day after the main shock", Scientific Reports 3, 2218 (2013). [2] T. Omi, Y. Ogata, Y. Hirata and K. Aihara, "Estimating the ETAS model from an early aftershock sequence", Geophysical Research Letters 41, 850 (2014). [3] T. Omi, Y. Ogata, Y. Hirata and K. Aihara, "Intermediate-term forecasting of aftershocks

  20. Aftershock communication during the Canterbury Earthquakes, New Zealand: implications for response and recovery in the built environment

    USGS Publications Warehouse

    Julia Becker,; Wein, Anne; Sally Potter,; Emma Doyle,; Ratliff, Jamie L.

    2015-01-01

    On 4 September 2010, a Mw7.1 earthquake occurred in Canterbury, New Zealand. Following the initial earthquake, an aftershock sequence was initiated, with the most significant aftershock being a Mw6.3 earthquake occurring on 22 February 2011. This aftershock caused severe damage to the city of Christchurch and building failures that killed 185 people. During the aftershock sequence it became evident that effective communication of aftershock information (e.g., history and forecasts) was imperative to assist with decision making during the response and recovery phases of the disaster, as well as preparedness for future aftershock events. As a consequence, a joint JCDR-USGS research project was initiated to investigate: • How aftershock information was communicated to organisations and to the public; • How people interpreted that information; • What people did in response to receiving that information; • What information people did and did not need; and • What decision-making challenges were encountered relating to aftershocks. Research was conducted by undertaking focus group meetings and interviews with a range of information providers and users, including scientists and science advisors, emergency managers and responders, engineers, communication officers, businesses, critical infrastructure operators, elected officials, and the public. The interviews and focus group meetings were recorded and transcribed, and key themes were identified. This paper focuses on the aftershock information needs for decision-making about the built environment post-earthquake, including those involved in response (e.g., for building assessment and management), recovery/reduction (e.g., the development of new building standards), and readiness (e.g. between aftershocks). The research has found that the communication of aftershock information varies with time, is contextual, and is affected by interactions among roles, by other information, and by decision objectives. A number

  1. Statistical monitoring of aftershock sequences: a case study of the 2015 Mw7.8 Gorkha, Nepal, earthquake

    NASA Astrophysics Data System (ADS)

    Ogata, Yosihiko; Tsuruoka, Hiroshi

    2016-03-01

    Early forecasting of aftershocks has become realistic and practical because of real-time detection of hypocenters. This study illustrates a statistical procedure for monitoring aftershock sequences to detect anomalies to increase the probability gain of a significantly large aftershock or even an earthquake larger than the main shock. In particular, a significant lowering (relative quiescence) in aftershock activity below the level predicted by the Omori-Utsu formula or the epidemic-type aftershock sequence model is sometimes followed by a large earthquake in a neighboring region. As an example, we detected significant lowering relative to the modeled rate after approximately 1.7 days after the main shock in the aftershock sequence of the Mw7.8 Gorkha, Nepal, earthquake of April 25, 2015. The relative quiescence lasted until the May 12, 2015, M7.3 Kodari earthquake that occurred at the eastern end of the primary aftershock zone. Space-time plots including the transformed time can indicate the local places where aftershock activity lowers (the seismicity shadow). Thus, the relative quiescence can be hypothesized to be related to stress shadowing caused by probable slow slips. In addition, the aftershock productivity of the M7.3 Kodari earthquake is approximately twice as large as that of the M7.8 main shock.

  2. Adaptive Competency Acquisition: Why LPN-to-ADN Career Mobility Education Programs Work.

    ERIC Educational Resources Information Center

    Coyle-Rogers, Patricia G.

    Adaptive competencies are the skills required to effectively complete a particular task and are the congruencies (balance) between personal skills and task demands. The differences between the adaptive competency acquisition of students in licensed practical nurse (LPN) programs and associate degree nurse (ADN) programs were examined in a…

  3. Community Organization and the Mobilization of Resources for Manpower Development Programs.

    ERIC Educational Resources Information Center

    Ferman, Louis A.

    This study tried to isolate some of the characteristics that account for the variation in community receptivity to federal aid programs. The communities selected for the study had a population of 25,000 or more and had been in existence prior to 1950. Community participation in the programs was measured by the absence or presence of communities in…

  4. Are Wellness/Fitness Programs Benefiting Participants' Movement and Mobility in Daily Life?

    ERIC Educational Resources Information Center

    Sparling, Phillip B.

    2005-01-01

    Knowledge regarding the potential benefits of participation in fitness programs to individuals' quality of movement in daily living is limited. It is important to study this relationship and also consider the implications for professional preparation programs in kinesiology. A brief overview based on published reports and expert opinions focuses…

  5. Programming Education with a Blocks-Based Visual Language for Mobile Application Development

    ERIC Educational Resources Information Center

    Mihci, Can; Ozdener, Nesrin

    2014-01-01

    The aim of this study is to assess the impact upon academic success of the use of a reference block-based visual programming tool, namely the MIT App Inventor for Android, as an educational instrument for teaching object-oriented GUI-application development (CS2) concepts to students; who have previously completed a fundamental programming course…

  6. Effects of a Task-specific Exercise Program on Balance, Mobility, and Muscle Strength in the Elderly

    PubMed Central

    Seo, Hyung-Seok; Lee, Jung-Ho; Park, Young-Han

    2014-01-01

    [Purpose] The aim of this study was to investigate the effects of a task-specific exercise program based on motor learning on balance ability and strength of the lower extremity in the elderly with/without falling experiences. [Subjects and Methods] Individuals who had experiences of falling over 2 times within the past 6 months were included in the falling group. The task-specific exercise program consisted of 3 stages (weeks 1–2, 3–4, and 5–6) and was conducted according to the level of difficulty in this study. [Results] The scores of the Korean version of the Activities-Specific Balance Confidence Scale and Performance-Oriented Mobility Assessment were significantly changed in both the falling group and non-falling group after the task-specific exercise program. In comparisons between the falling group and non-falling group, there were also significant differences in the Korean version of the Activities-Specific Balance Confidence Scale and muscle strength of the semitendinosus and gastrocnemius. [Conclusion] The task-specific exercise program has a positive effect on balance ability and muscle strength related to falls in the elderly. PMID:25435679

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  8. Texts for Talking: Evaluation of a Mobile Health Program Addressing Speech and Language Delay.

    PubMed

    Olson, Kaitlyn B; Wilkinson, Carol L; Wilkinson, M Jackson; Harris, Jamal; Whittle, Amy

    2016-10-01

    Speech and language delays are common developmental disorders that can lead to long-term academic and psychosocial impairments. Affected families often benefit from instruction in cultivating a language-rich home environment. This study investigated the feasibility of utilizing text messaging to deliver developmental education to families. Parents of children aged 11 to 36 months with concerning language development were enrolled in a 3-month text messaging program. Pre-program and post-program telephone surveys were completed. All enrolled parents were of low socioeconomic status, and 48% were monolingual Spanish speakers. A total of 27 parents (87%) completed the program and follow-up survey. After program completion, parents reported increased awareness of language-promoting activities and local child development resources (P = .002; P = .005). Parents also reported increased engagement in language-promoting activities (P = .004). The marginal program cost was 37 cents per participant. Findings from this pilot study indicate that text messaging is a feasible, engaging, and inexpensive platform for delivering developmental education to families.

  9. Texts for Talking: Evaluation of a Mobile Health Program Addressing Speech and Language Delay.

    PubMed

    Olson, Kaitlyn B; Wilkinson, Carol L; Wilkinson, M Jackson; Harris, Jamal; Whittle, Amy

    2016-10-01

    Speech and language delays are common developmental disorders that can lead to long-term academic and psychosocial impairments. Affected families often benefit from instruction in cultivating a language-rich home environment. This study investigated the feasibility of utilizing text messaging to deliver developmental education to families. Parents of children aged 11 to 36 months with concerning language development were enrolled in a 3-month text messaging program. Pre-program and post-program telephone surveys were completed. All enrolled parents were of low socioeconomic status, and 48% were monolingual Spanish speakers. A total of 27 parents (87%) completed the program and follow-up survey. After program completion, parents reported increased awareness of language-promoting activities and local child development resources (P = .002; P = .005). Parents also reported increased engagement in language-promoting activities (P = .004). The marginal program cost was 37 cents per participant. Findings from this pilot study indicate that text messaging is a feasible, engaging, and inexpensive platform for delivering developmental education to families. PMID:27554765

  10. Design and Development of a Telerehabilitation Self-Management Program for Persons with Chronic Lower Limb Swelling and Mobility Limitations: Preliminary Evidence

    PubMed Central

    Faett, Becky L.; Geyer, Mary Jo; Hoffman, Leslie A.; Brienza, David M.

    2012-01-01

    This paper describes design and development of a self-management program, delivered by telerehabilitation (TR), to address the problem of chronic lower limb swelling in persons with limited mobility. The 18.6 million persons with limited mobility in the USA are at increased risk for chronic lower limb swelling and related secondary complications, including cellulitis and skin ulcers. Over time, chronic swelling often progresses to lymphedema, an incurable condition requiring lifelong care. Without successful self-management, lymphedema and its related complications inevitably worsen. Access and adherence to appropriate treatment are challenging for persons with limited mobility. Program development involved a structured process to establish content validity (videos and manuals), readability, suitability, and selection of a TR platform to deliver the educational program. Our goal was to develop a program that would engage patients in self-management skills. The TR software platform chosen, Versatile and Integrated System for Telerehabilitation (VISYTER) was designed to facilitate face-to-face delivery of an interactive home-based self-management program via the internet in real time. Results demonstrated validity of the educational program and ease of use with TR. Future plans are to evaluate ability of this approach to promote self-management skills, home monitoring, and improved management of persons with lymphedema and limited mobility. PMID:23227323

  11. On the origin of diverse aftershock mechanisms following the 1989 Loma Prieta earthquake

    USGS Publications Warehouse

    Kilb, Debi; Ellis, M.; Gomberg, J.; Davis, S.

    1997-01-01

    We test the hypothesis that the origin of the diverse suite of aftershock mechanisms following the 1989 M 7.1 Loma Prieta, California, earthquake is related to the post-main-shock static stress field. We use a 3-D boundary-element algorithm to calculate static stresses, combined with a Coulomb failure criterion to calculate conjugate failure planes at aftershock locations. The post-main-shock static stress field is taken as the sum of a pre-existing stress field and changes in stress due to the heterogeneous slip across the Loma Prieta rupture plane. The background stress field is assumed to be either a simple shear parallel to the regional trend of the San Andreas fault or approximately fault-normal compression. A suite of synthetic aftershock mechanisms from the conjugate failure planes is generated and quantitatively compared (allowing for uncertainties in both mechanism parameters and earthquake locations) to well-constrained mechanisms reported in the US Geological Survey Northern California Seismic Network catalogue. We also compare calculated rakes with those observed by resolving the calculated stress tensor onto observed focal mechanism nodal planes, assuming either plane to be a likely rupture plane. Various permutations of the assumed background stress field, frictional coefficients of aftershock fault planes, methods of comparisons, etc. explain between 52 and 92 per cent of the aftershock mechanisms. We can explain a similar proportion of mechanisms however by comparing a randomly reordered catalogue with the various suites of synthetic aftershocks. The inability to duplicate aftershock mechanisms reliably on a one-to-one basis is probably a function of the combined uncertainties in models of main-shock slip distribution, the background stress field, and aftershock locations. In particular we show theoretically that any specific main-shock slip distribution and a reasonable background stress field are able to generate a highly variable suite of failure

  12. Tests of remote aftershock triggering by small mainshocks using Taiwan's earthquake catalog

    NASA Astrophysics Data System (ADS)

    Peng, W.; Toda, S.

    2014-12-01

    To understand earthquake interaction and forecast time-dependent seismic hazard, it is essential to evaluate which stress transfer, static or dynamic, plays a major role to trigger aftershocks and subsequent mainshocks. Felzer and Brodsky focused on small mainshocks (2≤M<3) and their aftershocks, and then argued that only dynamic stress change brings earthquake-to-earthquake triggering, whereas Richards-Dingers et al. (2010) claimed that those selected small mainshock-aftershock pairs were not earthquake-to-earthquake triggering but simultaneous occurrence of independent aftershocks following a larger earthquake or during a significant swarm sequence. We test those hypotheses using Taiwan's earthquake catalog by taking the advantage of lacking any larger event and the absence of significant seismic swarm typically seen with active volcano. Using Felzer and Brodsky's method and their standard parameters, we only found 14 mainshock-aftershock pairs occurred within 20 km distance in Taiwan's catalog from 1994 to 2010. Although Taiwan's catalog has similar number of earthquakes as California's, the number of pairs is about 10% of the California catalog. It may indicate the effect of no large earthquakes and no significant seismic swarm in the catalog. To fully understand the properties in the Taiwan's catalog, we loosened the screening parameters to earn more pairs and then found a linear aftershock density with a power law decay of -1.12±0.38 that is very similar to the one in Felzer and Brodsky. However, none of those mainshock-aftershock pairs were associated with a M7 rupture event or M6 events. To find what mechanism controlled the aftershock density triggered by small mainshocks in Taiwan, we randomized earthquake magnitude and location. We then found that those density decay in a short time period is more like a randomized behavior than mainshock-aftershock triggering. Moreover, 5 out of 6 pairs were found in a swarm-like temporal seismicity rate increase

  13. Discrete characteristics of the aftershock sequence of the 2011 Van earthquake

    NASA Astrophysics Data System (ADS)

    Toker, Mustafa

    2014-10-01

    An intraplate earthquake of magnitude Mw 7.2 occurred on a NE-SW trending blind oblique thrust fault in accretionary orogen, the Van region of Eastern Anatolia on October 23, 2011. The aftershock seismicity in the Van earthquake was not continuous but, rather, highly discrete. This shed light on the chaotic nonuniformity of the event distribution and played key roles in determining the seismic coupling between the rupturing process and seismogeneity. I analyzed the discrete statistical mechanics of the 2011 Van mainshock-aftershock sequence with an estimation of the non-dimensional tuning parameters consisting of; temporal clusters (C) and the random (RN) distribution of aftershocks, range of size scales (ROSS), strength change (εD), temperature (T), P-value of temporal decay, material parameter R-value, seismic coupling χ, and Q-value of aftershock distribution. I also investigated the frequency-size (FS), temporal (T) statistics and the sequential characteristics of aftershock dynamics using discrete approach and examined the discrete evolutionary periods of the Van earthquake Gutenberg-Richter (GR) distribution. My study revealed that the FS and T statistical properties of aftershock sequence represent the Gutenberg-Richter (GR) distribution, clustered (C) in time and random (RN) Poisson distribution, respectively. The overall statistical behavior of the aftershock sequence shows that the Van earthquake originated in a discrete structural framework with high seismic coupling under highly variable faulting conditions. My analyses relate this larger dip-slip event to a discrete seismogenesis with two main components of complex fracturing and branching framework of the ruptured fault and dynamic strengthening and hardening behavior of the earthquake. The results indicate two dynamic cases. The first is associated with aperiodic nature of aftershock distribution, indicating a time-independent Poissonian event. The second is associated with variable slip model

  14. When and where the aftershock activity was depressed: Contrasting decay patterns of the proximate large earthquakes in southern California

    USGS Publications Warehouse

    Ogata, Y.; Jones, L.M.; Toda, S.

    2003-01-01

    Seismic quiescence has attracted attention as a possible precursor to a large earthquake. However, sensitive detection of quiescence requires accurate modeling of normal aftershock activity. We apply the epidemic-type aftershock sequence (ETAS) model that is a natural extension of the modified Omori formula for aftershock decay, allowing further clusters (secondary aftershocks) within an aftershock sequence. The Hector Mine aftershock activity has been normal, relative to the decay predicted by the ETAS model during the 14 months of available data. In contrast, although the aftershock sequence of the 1992 Landers earthquake (M = 7.3), including the 1992 Big Bear earthquake (M = 6.4) and its aftershocks, fits very well to the ETAS up until about 6 months after the main shock, the activity showed clear lowering relative to the modeled rate (relative quiescence) and lasted nearly 7 years, leading up to the Hector Mine earthquake (M = 7.1) in 1999. Specifically, the relative quiescence occurred only in the shallow aftershock activity, down to depths of 5-6 km. The sequence of deeper events showed clear, normal aftershock activity well fitted to the ETAS throughout the whole period. We argue several physical explanations for these results. Among them, we strongly suspect aseismic slips within the Hector Mine rupture source that could inhibit the crustal relaxation process within "shadow zones" of the Coulomb's failure stress change. Furthermore, the aftershock activity of the 1992 Joshua Tree earthquake (M = 6.1) sharply lowered in the same day of the main shock, which can be explained by a similar scenario.

  15. Generalized Omori-Utsu law for aftershock sequences in southern California

    NASA Astrophysics Data System (ADS)

    Davidsen, J.; Gu, C.; Baiesi, M.

    2015-05-01

    We investigate the validity of a proposed generalized Omori-Utsu law for the aftershock sequences for the Landers, Hector Mine, Northridge and Superstition Hills earthquakes, the four largest events in the southern California catalogue we analyse. This law unifies three of the most prominent empirical laws of statistical seismology-the Gutenberg-Richter law, the Omori-Utsu law, and a generalized version of Båth's law-in a formula casting the parameters in the Omori-Utsu law as a function of the lower magnitude cutoff mc for the aftershocks considered. By applying a recently established general procedure for identifying aftershocks, we confirm that the generalized Omori-Utsu law provides a good approximation for the observed rates overall. In particular, we provide convincing evidence that the characteristic time c is not constant but a genuine function of mc, which cannot be attributed to short-term aftershock incompleteness. However, the estimation of the specific parameters is somewhat sensitive to the aftershock selection method used. This includes c(mc), which has important implications for inferring the underlying stress field.

  16. The southeastern Illinois earthquake of 10 June 1987: the later aftershocks

    USGS Publications Warehouse

    Langer, C.J.; Bollinger, G.A.

    1991-01-01

    The 10 June 1987 southeastern Illinois earthquake (mbLg=5.2) was located about 200 km east of St Louis, Missouri, caused minor damage in the epicentral area, had a contiguous felt area of about 433 000 km2, and had a total felt area over 1 million km2. Within 47 hours after the main shock, a 15-station aftershock monitoring network (later expanded to 21 instruments) was installed that recorded more than 100 aftershocks in the folllowing 4-day period. Results from the 56 aftershocks that were well located indicate a compact, cylindrically shaped aftershock volume about 1.7 km long, 0.8 km wide, and with a vertical distribution between about 9 and 12 km in depth. Composite focal mechanism solutions of the aftershocks suggest that the predominant mode of faulting is reverse slip, but some strike-slip type motion occurred similar to the mechanism for the main shock as determined from teleseismic data. The maximum principal compressive stress (P axes) is oriented E-ESE and is subhorizontal in plunge. -from Authors

  17. Aftershock triggering by postseismic stresses: A study based on Coulomb rate-and-state models

    NASA Astrophysics Data System (ADS)

    Cattania, Camilla; Hainzl, Sebastian; Wang, Lifeng; Enescu, Bogdan; Roth, Frank

    2015-04-01

    The spatiotemporal clustering of earthquakes is a feature of medium- and short-term seismicity, indicating that earthquakes interact. However, controversy exists about the physical mechanism behind aftershock triggering: static stress transfer and reloading by postseismic processes have been proposed as explanations. In this work, we use a Coulomb rate-and-state model to study the role of coseismic and postseismic stress changes on aftershocks and focus on two processes: creep on the main shock fault plane (afterslip) and secondary aftershock triggering by previous aftershocks. We model the seismic response to Coulomb stress changes using the Dieterich constitutive law and focus on two events: the Parkfield, Mw = 6.0, and the Tohoku, Mw = 9.0, earthquakes. We find that modeling secondary triggering systematically improves the maximum log likelihood fit of the sequences. The effect of afterslip is more subtle and difficult to assess for near-fault events, where model errors are largest. More robust conclusions can be drawn for off-fault aftershocks: following the Tohoku earthquake, afterslip promotes shallow crustal seismicity in the Fukushima region. Simple geometrical considerations indicate that afterslip-induced stress changes may have been significant on trench parallel crustal fault systems following several of the largest recorded subduction earthquakes. Moreover, the time dependence of afterslip strongly enhances its triggering potential: seismicity triggered by an instantaneous stress change decays more quickly than seismicity triggered by gradual loading, and as a result we find afterslip to be particularly important between few weeks and few months after the main shock.

  18. Modelling aftershock migration and afterslip of the San Juan Bautista, California, earthquake of October 3, 1972

    USGS Publications Warehouse

    Wesson, R.L.

    1987-01-01

    The San Juan Bautista earthquake of October 3, 1972 (ML = 4.8), located along the San Andreas fault in central California, initiated an aftershock sequence characterized by a subtle, but perceptible, tendency for aftershocks to spread to the northwest and southeast along the fault zone. The apparent dimension of the aftershock zone along strike increased from about 7-10 km within a few days of the earthquake, to about 20 km eight months later. In addition, the mainshock initiated a period of accelerated fault creep, which was observed at 2 creep meters situated astride the trace of the San Andreas fault within about 15 km of the epicenter of the mainshock. The creep rate gradually returned to the preearthquake rate after about 3 yrs. Both the spreading of the aftershocks and the rapid surface creep are interpreted as reflecting a period of rapid creep in the fault zone representing the readjustment of stress and displacement following the failure of a "stuck" patch or asperity during the San Juan Bautista earthquake. Numerical calculations suggest that the behavior of the fault zone is consistent with that of a material characterized by a viscosity of about 3.6??1014 P, although the real rheology is likely to be more complicated. In this model, the mainshock represents the failure of an asperity that slips only during earthquakes. Aftershocks represent the failure of second-order asperities which are dragged along by the creeping fault zone. ?? 1987.

  19. Analysing the 1811-1812 New Madrid earthquakes with recent instrumentally recorded aftershocks.

    PubMed

    Mueller, Karl; Hough, Susan E; Bilham, Roger

    2004-05-20

    Although dynamic stress changes associated with the passage of seismic waves are thought to trigger earthquakes at great distances, more than 60 per cent of all aftershocks appear to be triggered by static stress changes within two rupture lengths of a mainshock. The observed distribution of aftershocks may thus be used to infer details of mainshock rupture geometry. Aftershocks following large mid-continental earthquakes, where background stressing rates are low, are known to persist for centuries, and models based on rate-and-state friction laws provide theoretical support for this inference. Most past studies of the New Madrid earthquake sequence have indeed assumed ongoing microseismicity to be a continuing aftershock sequence. Here we use instrumentally recorded aftershock locations and models of elastic stress change to develop a kinematically consistent rupture scenario for three of the four largest earthquakes of the 1811-1812 New Madrid sequence. Our results suggest that these three events occurred on two contiguous faults, producing lobes of increased stress near fault intersections and end points, in areas where present-day microearthquakes have been hitherto interpreted as evidence of primary mainshock rupture. We infer that the remaining New Madrid mainshock may have occurred more than 200 km north of this region in the Wabash Valley of southern Indiana and Illinois--an area that contains abundant modern microseismicity, and where substantial liquefaction was documented by historic accounts. Our results suggest that future large mid-plate earthquake sequences may extend over a much broader region than previously suspected.

  20. Analysing the 1811-1812 New Madrid earthquakes with recent instrumentally recorded aftershocks

    USGS Publications Warehouse

    Mueller, K.; Hough, S.E.; Bilham, R.

    2004-01-01

    Although dynamic stress changes associated with the passage of seismic waves are thought to trigger earthquakes at great distances, more than 60 per cent of all aftershocks appear to be triggered by static stress changes within two rupture lengths of a mainshock. The observed distribution of aftershocks may thus be used to infer details of mainshock rupture geometry. Aftershocks following large mid-continental earthquakes, where background stressing rates are low, are known to persist for centuries, and models based on rate-and-state friction laws provide theoretical support for this inference. Most past studies of the New Madrid earthquake sequence have indeed assumed ongoing microseismicity to be a continuing aftershock sequence. Here we use instrumentally recorded aftershock locations and models of elastic stress change to develop a kinematically consistent rupture scenario for three of the four largest earthquakes of the 1811-1812 New Madrid sequence. Our results suggest that these three events occurred on two contiguous faults, producing lobes of increased stress near fault intersections and end points, in areas where present-day microearthquakes have been hitherto interpreted as evidence of primary mainshock rupture. We infer that the remaining New Madrid mainshock may have occurred more than 200 km north of this region in the Wabash Valley of southern Indiana and Illinois-an area that contains abundant modern microseismicity, and where substantial liquefaction was documented by historic accounts. Our results suggest that future large midplate earthquake sequences may extend over a much broader region than previously suspected.

  1. Thrust-faulting earthquake induced many normal-faulting aftershocks, in northeastern Chiba Prefecture, Japan

    NASA Astrophysics Data System (ADS)

    Sakai, S.; Kato, A.; Hirata, N.; Nakagawa, S.; Kasahara, K.; Sato, H.; Kurashimo, E.; Nanjo, K.; Panayotopoulos, Y.; Obara, K.; Aketagawa, T.; Kimura, H.

    2010-12-01

    A thrust faulting type earthquake of a local body wave magnitude (MJMA) of 4.9 occurred near the upper interface of the subducting Philippine Sea Plate (PHS) in northeastern Chiba Prefecture on July 22, 2010. We have been developing a dense seismic net work call the MeSO-net in the Tokyo Metropolitan area. So far, 249 stations are available for the study of a large felt earthquakes and small event as low as M=1.5. We also deployed a temporary seismic array 24 of which were used for the analysis of the aftershocks. We locate the July 22 earthquake(MJMA=4.9) and its 19 aftershocks (M>1.5) by the double difference location algorithm. We also determine focal mechanisms for the main- and after-shocks. The locations of the main shock and three aftershocks are closely distributed near the upper interface of PHS, which is consistent with the idea that the event occurred on the plate interface. However, most aftershocks whose focal mechanism is normal-fault type with a T-axis directing NE-SW are located off the upper interface indicating that intra-slab events are also generated by the event. Acknowledgement: The present study is supported by Special Project for Earthquake Disaster Mitigation in Tokyo Metropolitan Area from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.

  2. Decay of aftershock density with distance does not indicate triggering by dynamic stress

    USGS Publications Warehouse

    Richards-Dinger, K.; Stein, R.S.; Toda, S.

    2010-01-01

    Resolving whether static or dynamic stress triggers most aftershocks and subsequent mainshocks is essential to understand earthquake interaction and to forecast seismic hazard. Felzer and Brodsky examined the distance distribution of earthquakes occurring in the first five minutes after 2 ≤ M  M  M ≥ 2 aftershocks showed a uniform power-law decay with slope −1.35 out to 50 km from the mainshocks. From this they argued that the distance decay could be explained only by dynamic triggering. Here we propose an alternative explanation for the decay, and subject their hypothesis to a series of tests, none of which it passes. At distances more than 300 m from the 2 ≤  M< 3 mainshocks, the seismicity decay 5 min before the mainshocks is indistinguishable from the decay five minutes afterwards, indicating that the mainshocks have no effect at distances outside their static triggering range. Omori temporal decay, the fundamental signature of aftershocks, is absent at distances exceeding 10 km from the mainshocks. Finally, the distance decay is found among aftershocks that occur before the arrival of the seismic wave front from the mainshock, which violates causality. We argue that Felzer and Brodsky implicitly assume that the first of two independent aftershocks along a fault rupture triggers the second, and that the first of two shocks in a creep- or intrusion-driven swarm triggers the second, when this need not be the case.

  3. Barriers and Challenges to the Successful Implementation of an Intensive Care Unit Mobility Program: Understanding Systems and Human Factors in Search for Practical Solutions.

    PubMed

    Honiden, Shyoko; Connors, Geoffrey R

    2015-09-01

    ICU-acquired weakness is a common problem and carries significant morbidity. Despite evidence that early mobility can mitigate this, implementation outside of the research setting is lagging. Understanding barriers at the systems as well as individual level is a crucial step in successful implementation of an ICU mobility program. This includes taking inventory of waste, overburden and inconsistencies in the work environment. Appreciating regulative, normative as well as cultural forces at work is critical. Finally, key personnel, which include organizational leaders, innovation champions and end users of the proposed change need to be accounted for at each step during program implementation.

  4. Barriers and Challenges to the Successful Implementation of an Intensive Care Unit Mobility Program: Understanding Systems and Human Factors in Search for Practical Solutions.

    PubMed

    Honiden, Shyoko; Connors, Geoffrey R

    2015-09-01

    ICU-acquired weakness is a common problem and carries significant morbidity. Despite evidence that early mobility can mitigate this, implementation outside of the research setting is lagging. Understanding barriers at the systems as well as individual level is a crucial step in successful implementation of an ICU mobility program. This includes taking inventory of waste, overburden and inconsistencies in the work environment. Appreciating regulative, normative as well as cultural forces at work is critical. Finally, key personnel, which include organizational leaders, innovation champions and end users of the proposed change need to be accounted for at each step during program implementation. PMID:26304280

  5. Development of Proof-of-Concept Units for the Advanced Medium-Sized Mobile Power Sources (AMMPS) Program

    SciTech Connect

    Andriulli, JB

    2002-04-03

    The purpose of this report is to document the development of the proof-of-concept units within the Advanced Medium-sized Mobile Power Sources (AMMPS) program. The design used a small, lightweight diesel engine, a permanent magnet alternator, power electronics and digital controls as outlined in the philosophy detailed previously. One small proof-of-concept unit was completed and delivered to the military. The unit functioned well but was not optimized at the time of delivery to the military. A tremendous amount of experience was gained during this phase that can be used in the development of any follow-on AMMPS production systems. Lessons learned and recommendations for follow-on specifications are provided. The unit demonstrated that significant benefits are possible with the new design philosophy. Trade-offs will have to be made but many of the advantages appear to be within the technical grasp of the market.

  6. Mobilizing Volunteer Tutors to Improve Student Literacy: Implementation, Impacts, and Costs of the Reading Partners Program

    ERIC Educational Resources Information Center

    Tepper Jacob, Robin; Armstrong, Catherine; Willard, Jacklyn Altuna

    2015-01-01

    This study reports on an evaluation of the "Reading Partners" program, which uses community volunteers to provide one-on-one tutoring to struggling readers in underresourced elementary schools. Established in 1999 in East Menlo Park, California, the mission of "Reading Partners" is to help children become lifelong readers by…

  7. Financing and Sustaining Mobility Programs in Rural Areas: A Manual. Final Report.

    ERIC Educational Resources Information Center

    Wallin, Theodore A.; Kidder, Alice

    This manual focuses on the start-up and operation of low-cost transportation in rural areas. A principal focus is the use of volunteers and/or the consolidation of rides through a brokerage program. Chapter One provides an overview of what financial and operating decisions must be made to design a volunteer system. Chapter Two describes easy…

  8. The impact of an air quality advisory program on voluntary mobile source air pollution reduction

    NASA Astrophysics Data System (ADS)

    Blanken, Peter D.; Dillon, Jennifer; Wismann, Genevieve

    Air pollution from mobile source emissions is a major cause of air quality degradation in the Denver, Colorado, metropolitan area. The projected increase in both population and vehicle miles driven, coupled with the high altitude, predominantly clear skies, and prevalent wintertime temperature inversions aid in the formation and retention of pollutants. The Colorado Department of Public Health issues an air quality advisory daily during the high pollution season (November 1-March 31) with the objective of improving air quality through voluntary driving restrictions and a mandatory wood burning ban. We hypothesized that the advisory had no effect on commuter behavior due to lack of awareness and understanding, lack of alternative means of travel, or lack of concern. We mailed an anonymous, self-administered survey to 1000 commuters living in the cities of Boulder and Westminster, Colorado. Despite the fact that the vast majority of the respondents were aware of the daily advisory (94%), understood what it meant (93%), and heard the posting at least once a day (71%) in time to choose alternative forms of transportation, the advisory did not alter commuter travel. Commuters traveled mainly as the sole occupant of a car and most (76%) never changed the way they commuted based on the daily advisory. Many claimed schedules or work locations did not allow them to use alternative transportation methods. We suggested a practical way to improve the advisory would be to reduce or eliminate public transit fares on poor air quality days.

  9. Three ingredients for Improved global aftershock forecasts: Tectonic region, time-dependent catalog incompleteness, and inter-sequence variability

    USGS Publications Warehouse

    Page, Morgan T.; Van Der Elst, Nicholas; Hardebeck, Jeanne L.; Felzer, Karen; Michael, Andrew J.

    2016-01-01

    Following a large earthquake, seismic hazard can be orders of magnitude higher than the long‐term average as a result of aftershock triggering. Because of this heightened hazard, emergency managers and the public demand rapid, authoritative, and reliable aftershock forecasts. In the past, U.S. Geological Survey (USGS) aftershock forecasts following large global earthquakes have been released on an ad hoc basis with inconsistent methods, and in some cases aftershock parameters adapted from California. To remedy this, the USGS is currently developing an automated aftershock product based on the Reasenberg and Jones (1989) method that will generate more accurate forecasts. To better capture spatial variations in aftershock productivity and decay, we estimate regional aftershock parameters for sequences within the García et al. (2012) tectonic regions. We find that regional variations for mean aftershock productivity reach almost a factor of 10. We also develop a method to account for the time‐dependent magnitude of completeness following large events in the catalog. In addition to estimating average sequence parameters within regions, we develop an inverse method to estimate the intersequence parameter variability. This allows for a more complete quantification of the forecast uncertainties and Bayesian updating of the forecast as sequence‐specific information becomes available.

  10. Missing data in aftershock sequences: explaining the deviations from scaling laws.

    PubMed

    Lennartz, Sabine; Bunde, Armin; Turcotte, Donald L

    2008-10-01

    In this paper we extend the branching aftershock sequence model to study the role of missing data at short times and small amplitudes after a mainshock. We apply this model, which contains three parameters characterizing the missing data, to the magnitude and temporal statistics of four aftershock sequences in California. We find that the observed time-dependent deviations of the frequency-magnitude scaling from the Gutenberg-Richter power law dependency can be described quantitatively by the model. We also show that, for the same set of parameters, the model is able to explain quantitatively the observed magnitude-dependent deviations of the temporal decay of aftershocks from Omori's law. In addition, we show that the same sets of data can also reproduce quite well the various functional forms of the probability density functions of the return times between consecutive events with magnitudes above a prescribed threshold, as well as the violation of scaling at short and intermediate time scales.

  11. Scaling Analysis of Time Distribution between Successive Earthquakes in Aftershock Sequences

    NASA Astrophysics Data System (ADS)

    Marekova, Elisaveta

    2016-08-01

    The earthquake inter-event time distribution is studied, using catalogs for different recent aftershock sequences. For aftershock sequences following the Modified Omori's Formula (MOF) it seems clear that the inter-event distribution is a power law. The parameters of this law are defined and they prove to be higher than the calculated value (2 - 1/p). Based on the analysis of the catalogs, it is determined that the probability densities of the inter-event time distribution collapse into a single master curve when the data is rescaled with instantaneous intensity, R(t; Mth), defined by MOF. The curve is approximated by a gamma distribution. The collapse of the data provides a clear view of aftershock-occurrence self-similarity.

  12. Mitochondrial Translocation of High Mobility Group Box 1 Facilitates LIM Kinase 2-Mediated Programmed Necrotic Neuronal Death.

    PubMed

    Hyun, Hye-Won; Ko, Ah-Reum; Kang, Tae-Cheon

    2016-01-01

    High mobility group box 1 (HMGB1) acts a signaling molecule regulating a wide range of inflammatory responses in extracellular space. HMGB1 also stabilizes nucleosomal structure and facilitates gene transcription. Under pathophysiological conditions, nuclear HMGB1 is immediately transported to the cytoplasm through chromosome region maintenance 1 (CRM1). Recently, we have reported that up-regulation of LIM kinase 2 (LIMK2) expression induces HMGB1 export from neuronal nuclei during status epilepticus (SE)-induced programmed neuronal necrosis in the rat hippocampus. Thus, we investigated whether HMGB1 involves LIMK2-mediated programmed neuronal necrosis, but such role is not reported. In the present study, SE was induced by pilocarpine in rats that were intracerebroventricularly infused with saline, control siRNA, LIMK2 siRNA or leptomycin B (LMB, a CRM1 inhibitor) prior to SE induction. Thereafter, we performed Fluoro-Jade B staining, western blots and immunohistochemical studies. LIMK2 knockdown effectively attenuated SE-induced neuronal death and HMGB1 import into mitochondria accompanied by inhibiting nuclear HMGB1 release and abnormal mitochondrial elongation. LMB alleviated SE-induced neuronal death and nuclear HMGB1 release. However, LMB did not prevent mitochondrial elongation induced by SE, but inhibited the HMGB1 import into mitochondria. The efficacy of LMB was less effective to attenuate SE-induced neuronal death than that of LIMK2 siRNA. These findings indicate that nuclear HMGB1 release and the subsequent mitochondrial import may facilitate and deteriorate programmed necrotic neuronal deaths. The present data suggest that the nuclear HMGB1 release via CRM1 may be a potential therapeutic target for the programmed necrotic neuronal death induced by SE. PMID:27147971

  13. Strong aftershocks in the northern segment of the Wenchuan earthquake rupture zone and their seismotectonic implications

    NASA Astrophysics Data System (ADS)

    Zheng, Yong; Ni, Sidao; Xie, Zujun; Lv, Jian; Ma, Hongsheng; Sommerville, Paul

    2010-11-01

    More than 28, 000 aftershocks have occurred since the 05/12/2008 Wenchuan earthquake, with dozens of them stronger than M 5. Since July, 2008, all the M > 5 earthquakes have occurred only in the northern segment of the rupture zone, suggesting obvious seismicity segmentation. We applied the double difference method to relocate all of the M > 3 aftershocks. After relocation, the aftershocks show a compact zone of seismicity, with a length of about 300 km and average width of 30 km, supporting that the hypothesis that the Beichuan-Yingxiu and Chaping-Linjiaan faults are the faults that ruptured in the earthquake. With the Cut and Paste (CAP) waveform inversion algorithm, we determined the source mechanism and focal depth of all the > M 5 aftershocks in the northern segments. The number of thrust events is close to the number of strike-slip events, but almost all of the events with thrust mechanism are distributed over the northern segment, while the aftershocks with strike-slip mechanism only occurred at the north-easternmost end, contrasting with field observations of a substantial strike-slip component of surface rupture over the northern segment. The events with strike-slip mechanism occurred at depths up to 18 km, consistent with the lack of surface rupture in the north-easternmost section. However, since early August, very shallow events (2 km) with thrust mechanism have occurred, probably releasing the strain energy of the unruptured fault in the north-easternmost section. It seems that the seismic hazard potential of the northern segment is still quite high, and more studies are needed to resolve some of the discrepancy suggested by aftershock patterns and other observations.

  14. Aftershocks of the june 20, 1978, Greece earthquake: A multimode faulting sequence

    USGS Publications Warehouse

    Carver, D.; Bollinger, G.A.

    1981-01-01

    A 10-station portable seismograph network was deployed in northern Greece to study aftershocks of the magnitude (mb) 6.4 earthquake of June 20, 1978. The main shock occurred (in a graben) about 25 km northeast of the city of Thessaloniki and caused an east-west zone of surface rupturing 14 km long that splayed to 7 km wide at the west end. The hypocenters for 116 aftershocks in the magnitude range from 2.5 to 4.5 were determined. The epicenters for these events cover an area 30 km (east-west) by 18 km (north-south), and focal depths ranges from 4 to 12 km. Most of the aftershocks in the east half of the aftershock zone are north of the surface rupture and north of the graben. Those in the west half are located within the boundaries of the graben. Composite focalmechanism solutions for selected aftershocks indicate reactivation of geologically mapped normal faults in the area. Also, strike-slip and dip-slip faults that splay off the western end of the zone of surface ruptures may have been activated. The epicenters for four large (M ??? 4.8) foreshocks and the main shock were relocated using the method of joint epicenter determination. Collectively, those five epicenters form an arcuate pattern convex southward, that is north of and 5 km distant from the surface rupturing. The 5-km separation, along with a focal depth of 8 km (average aftershock depth) or 16 km (NEIS main-shock depth), implies that the fault plane dips northward 58?? or 73??, respectively. A preferred nodal-plane dip of 36?? was determined by B.C. Papazachos and his colleagues in 1979 from a focal-mechanism solution for the main shock. If this dip is valid for the causal fault and that fault projects to the zone of surface rupturing, a decrease of dip with depth is required. ?? 1981.

  15. The earthquake and its aftershocks from May 2 through September 30, 1983

    SciTech Connect

    Eaton, J.P.

    1990-01-01

    Analysis of the Coalinga earthquake sequence, based on the Allen/Ellis real-time-processor (RTP) automatic P-phase-onset times and duration measurements, provides hypocentral and magnitude determinations for more than 6,000 events from May 2 through September 30, 1983. Focal mechanisms and local magnitudes of more than 140 of the larger aftershocks were calculated from more detailed observations obtained from magnetic-tape playbacks from both the temporary Coalinga seismic network and the permanent telemetered central California seismic network (Calnet). The combined catalog appears to be substantially complete for events of M {ge} 3 within about 3 hours, and for events of M {ge} 1.7 within about 1 day, after the main shock. The first-motion plot of the main shock offers two choices for the main-shock fault; a thrust fault striking N. 53{degree}W. and dipping 23{degree}SW. (the preferred fault plane), or a high-angle reverse fault striking N. 53{degree}W. and dipping 67{degree}NE. Focal mechanisms of the larger aftershocks also indicate predominantly thrust or reverse faulting. The long axis of the aftershock zone, which is 35 km long and 15 to 20 km wide, coincides with the axis of the Anticline Ridge-Guijarral Hills structure at the Coast Ranges-Great Valley boundary northeast of Coalinga. A transverse (southwest to northeast) quiet band with very few events crosses the aftershock zone where northwest-trending Anticline Ridge joins broader, east-west-trending Joaquin Ridge just northwest of the main shock. The smaller aftershocks occur mostly in the hanging-wall blocks above the faults outlined by the larger aftershocks.

  16. GIS-based 3D visualization of the Mw 7.7, 2007, Tocopilla aftershocks

    NASA Astrophysics Data System (ADS)

    Eggert, S.; Sobiesiak, M.; Altenbrunn, K.

    2009-12-01

    The November 14, 2007 Mw 7.7 earthquake nucleated on the west coast of northern Chile about 40 km east of the city of Tocopilla. It took place in the southern part of a large seismic gap, the Iquique subduction zone segment which is supposed to be at the end of its seismic cycle. The Tocopilla fault plane appears to be the northern continuation of the Mw 8.0, 1995 Antofagasta earthquake. We present a complex 3D model of the rupture area including first hypocenter localizations of aftershocks following the event. The data was recorded during a mission of the German Task Force for Earthquakes after the 2007 Tocopilla earthquake. The seismic stations were recording the aftershocks from November 2007 until May 2008. In general, subduction zones have a complex structure where most of the volumes examined are characterized by strong variations in physical and material parameters. Therefore, 3D representation of the geophysical and geological conditions to be found are of great importance to understand such a subduction environment. We start with a two-dimensional visualization of the geological and geophysical setting. In a second step, we use GIS as a three-dimensional modeling tool which gives us the possibility to visualize the complex geophysical processes. One can easily add and delete data and focus on the information one needs. This allows us to investigate the aftershock distribution along the subducting slab and identify clear structures and clusters within the data set. Furthermore we combine the 2007 Tocopilla data set with the 1995 Antofagasta aftershocks which provides a new, three-dimensional insight into the segment boundary of these two events. Analyzing the aftershock sequence with a GIS-based model will not only help to visualize the setting but also be the base for various calculations and further explorations of the complex structures. Aftershocks following the 1995 Antofagasta earthquake and the 2007 Tocopilla earthquake

  17. An exploration of reported cognitions during an earthquake and its aftershocks: differences across affected communities and associations with psychological distress.

    PubMed

    Kannis-Dymand, Lee; Dorahy, Martin J; Crake, Rosemary; Gibbon, Peter; Luckey, Rhys

    2015-04-01

    Cognitive themes in two communities differentially affected by the September 2010 Christchurch earthquake and aftershocks were investigated. Participants (N = 124) completed questions about their thoughts during the earthquake and aftershocks as well as measures of acute stress, anxiety, and depression. Cognitions were qualitatively analyzed into themes for the earthquake and aftershocks. Themes were examined for differences across the two suburbs and associations with psychological distress. Nine cognitive themes were identified within three superordinate domains. The cognitive theme of worry and concern was the most frequently occurring for the earthquake and aftershocks across the whole sample and for the more affected suburb. Current threat was the most frequent theme for the earthquake in the less affected suburb, whereas worry and concern was the most evident in this group for aftershocks. The superordinate theme of threat was significantly related to higher acute stress disorder scores in the more affected suburb for earthquake-reported cognitions.

  18. DETERMINATION OF ELASTIC WAVE VELOCITY AND RELATIVE HYPOCENTER LOCATIONS USING REFRACTED WAVES. II. APPLICATION TO THE HAICHENG, CHINA, AFTERSHOCK SEQUENCE.

    USGS Publications Warehouse

    Shedlock, Kaye M.; Jones, Lucile M.; Ma, Xiufang

    1985-01-01

    The authors located the aftershocks of the February 4, 1975 Haicheng, China, aftershock sequence using an arrival time difference (ATD) simultaneous inversion method for determining the near-source (in situ) velocity and the location of the aftershocks with respect to a master event. The aftershocks define a diffuse zone, 70 km multiplied by 25 km, trending west-northwest, perpendicular to the major structural trend of the region. The main shock and most of the large aftershocks have strike-slip fault plane solutions. The preferred fault plane strikes west-northwest, and the inferred sense of motion is left-lateral. The entire Haicheng earthauake sequence appears to have been the response of an intensely faulted range boundary to a primarily east-west crustal compression and/or north-south extension.

  19. Spatial and temporal analysis of the Mw 7.7, 2007, Tocopilla aftershock sequence

    NASA Astrophysics Data System (ADS)

    Eggert, Silke; Sobiesiak, Monika

    2010-05-01

    On 14 November 2007, 15:40:51 UTC a large Mw 7.7 earthquake occurred in the region of Tocopilla in Northern Chile. The epicenter is located at 22.30°S, 69.89°W, ~ 35 km south east of the city of Tocopilla and 160 km north of Antofagasta (earthquake location by GEOFON network). The earthquake took place in the southern part of the Northern Chile seismic gap which is supposed to be at the end of its seismic cycle. Currently, the gap is spanning the rupture area of the Mw=9 1877 Iquique event, a region which is now unbroken for almost 150 years. Therefore, the 2007 Tocopilla earthquake is the first large event that occurred inside the Northern Chile seismic gap since 1877. We present a study of the spatial and temporal distribution of the aftershock activity following the 2007 Tocopilla event using the frequency-magnitude distribution and other parameters. Studying this aftershock sequence will provide closer insight into the fault dimension of this subduction zone earthquake and the tectonic setting of the region. The distribution of aftershocks into depth shows that the majority of the hypocenters are located along the subduction interface, reaching down to ~ 50 km depth. In the western part, the aftershock sequence splits into two branches, one heading towards the trench, the other bending into the crust in front of the Mejillones Peninsula. In the epicentral horizontal, we observe a concentration of aftershocks around the northern part of the Mejillones Peninsula and along the coast up to the Río Loa. This leads to the conclusion that the shallow part in the north west did probably not break during the event. The spatial density of aftershocks shows two offshore patches north-east of the peninsula. Analyzing the spatio-temporal distribution of our aftershock data set, we can see that the fault rupture propagated towards the south west with a fault plane of about 150 km length. These observations are consistent with first results by other studies. Our

  20. Seven Years Later: Effects of a Neighborhood Mobility Program on Poor Black and Latino Adults’ Well-being*

    PubMed Central

    FAUTH, REBECCA C.; LEVENTHAL, TAMA; BROOKS-GUNN, JEANNE

    2011-01-01

    This study explored program effects on adults’ well-being seven years following the implementation of a court-ordered neighborhood mobility program. Low-income black and Latino adults residing in poor, segregated neighborhoods in Yonkers, New York were randomly selected to relocate to publicly funded town-houses in middle-class neighborhoods within the city. Adults who moved (n = 141) and demographically similar adults who were not selected to move (n = 106) were interviewed. Data indicate that 85 percent of adults who moved to the new housing remained there at follow-up. Results revealed that adults who moved resided in neighborhoods with higher collective efficacy and less disorder and danger, but had fewer neighborhood social ties than adults who stayed in poor neighborhoods. Movers were also more likely to work and less likely to receive welfare than nonmovers. Adults who remained in low-poverty neighborhoods at the time of the follow-up reported better physical health than adults residing in poor neighborhoods, but mental health did not vary by neighborhood. PMID:18649497

  1. Mobility: A Multivariate Study of Academic Achievement in Reading and Math for Eighth-Grade Students as Measured by the Tennessee Comprehensive Assessment Program

    ERIC Educational Resources Information Center

    Donnelly, Margaret M.

    2010-01-01

    The primary purpose of this study was to determine if there was a difference between levels of student mobility in reading and mathematics achievement as measured by the 2007-2008 Tennessee Comprehensive Assessment Program (TCAP) achievement test. The study also sought to determine if there existed a difference in socioeconomic and attendance…

  2. Exploring the use of mobile phone technology for the enhancement of the prevention of mother-to-child transmission of HIV program in Nyanza, Kenya: a qualitative study

    PubMed Central

    2013-01-01

    Background Community-based mobile phone programs can complement gaps in clinical services for prevention of mother-to-child transmission (PMTCT) of HIV in areas with poor infrastructure and personnel shortages. However, community and health worker perceptions on optimal mobile phone communication for PMTCT are underexplored. This study examined what specific content and forms of mobile communication are acceptable to support PMTCT. Methods Qualitative methods using focus groups and in-depth interviews were conducted in two district hospitals in Nyanza Province, Kenya. A total of 45 participants were purposefully selected, including HIV-positive women enrolled in PMTCT, their male partners, community health workers, and nurses. Semi-structured discussion guides were used to elicit participants’ current mobile phone uses for PMTCT and their perceived benefits and challenges. We also examined participants’ views on platform design and gender-tailored short message service (SMS) messages designed to improve PMTCT communication and male involvement. Results Most participants had access to a mobile phone and prior experience receiving and sending SMS, although phone sharing was common among couples. Mobile phones were used for several health-related purposes, primarily as voice calls rather than texts. The perceived benefits of mobile phones for PMTCT included linking with health workers, protecting confidentiality, and receiving information and reminders. Men and women considered the gender-tailored SMS as a catalyst for improving PMTCT male involvement and couples’ communication. However, informative messaging relayed safely to the intended recipient was critical. In addition, health workers emphasized the continual need for in-person counseling coupled with, rather than replaced by, mobile phone reinforcement. For all participants, integrated and neutral text messaging provided antenatally and postnatally was most preferred, although not all topics or text

  3. Aftershock source mechanisms from the June 9, 1994, Deep Bolivian Earthquake

    NASA Astrophysics Data System (ADS)

    Tinker, Mark Andrew; Wallace, Terry C.; Beck, Susan L.; Silver, Paul G.; Zandt, George

    The Mw 8.3 Bolivia earthquake occurred on June 9, 1994, at a depth of 636 km. This is the largest deep event in recorded history and ruptured a portion of the down-going Nazca slab unknown to have ruptured previously. We recorded the main shock and aftershocks on the BANJO and SEDA portable, broadband seismic arrays deployed in Bolivia during this event. Myers et al. (this issue) identified and located 36 aftershocks (M>2) for the 10-day period following the main shock. We use a grid search technique to determine focal mechanisms for 12 of these aftershocks ranging in magnitude from 2.7 to 5.3. We compare the observed P to SV and SH ratios to a series of synthetics that represent different fault plane orientations. We find consistent focal mechanisms with the T-axis roughly horizontal and oriented approximately east-west, and the P-axis predominantly vertical. The aftershock focal mechanisms indicate a rotation of the P-axis within the slab from down-dip compression prior to the main shock to a near-vertical direction afterwards. This observation is consistent with the release of shear stress on the near-horizontal rupture plane and the subsequent rotation of the maximum compressive stress to a fault -normal orientation.

  4. Aftershocks driven by a high-pressure CO2 source at depth.

    PubMed

    Miller, Stephen A; Collettini, Cristiano; Chiaraluce, Lauro; Cocco, Massimo; Barchi, Massimiliano; Kaus, Boris J P

    2004-02-19

    In northern Italy in 1997, two earthquakes of magnitudes 5.7 and 6 (separated by nine hours) marked the beginning of a sequence that lasted more than 30 days, with thousands of aftershocks including four additional events with magnitudes between 5 and 6. This normal-faulting sequence is not well explained with models of elastic stress transfer, particularly the persistence of hanging-wall seismicity that included two events with magnitudes greater than 5. Here we show that this sequence may have been driven by a fluid pressure pulse generated from the coseismic release of a known deep source of trapped high-pressure carbon dioxide (CO2). We find a strong correlation between the high-pressure front and the aftershock hypocentres over a two-week period, using precise hypocentre locations and a simple model of nonlinear diffusion. The triggering amplitude (10-20 MPa) of the pressure pulse overwhelms the typical (0.1-0.2 MPa) range from stress changes in the usual stress triggering models. We propose that aftershocks of large earthquakes in such geologic environments may be driven by the coseismic release of trapped, high-pressure fluids propagating through damaged zones created by the mainshock. This may provide a link between earthquakes, aftershocks, crust/mantle degassing and earthquake-triggered large-scale fluid flow.

  5. Aftershock seismicity and Tectonic Setting of the 16 September 2015 Mw 8.3 Illapel earthquake

    NASA Astrophysics Data System (ADS)

    Lange, Dietrich; Geersen, Jacob; Barrientos, Sergio; Moreno, Marcos; Grevemeyer, Ingo; Contreras-Reyes, Eduardo; Kopp, Heidrun

    2016-04-01

    Powerful subduction zone earthquakes rupture thousands of square kilometers along continental margins but at certain locations earthquake rupture terminates. On 16 September 2015 the Mw. 8.3 Illapel earthquake ruptured a 200 km long stretch of the Central Chilean subduction zone, triggering a tsunami and causing significant damage. Here we analyze the spatial pattern of coseismic rupture and the temporal and spatial pattern of local seismicity for aftershocks and foreshocks in relation to the tectonic setting in the earthquake area. Aftershock seismicity surrounds the rupture area in lateral and downdip direction. For the first 24 hours following the mainshock we observe aftershock migration to both lateral directions with velocities of approximately 2.5 and 5 km/h. At the southern earthquake boundary aftershocks cluster around individual subducted seamounts located on the prolongation of the downthrusting Juan Fernández Ridge indicating stress transfer from the main rupture area. In the northern part of the rupture area a deeper band of local seismicity is observed indicating an alternation of seismic to aseismic behavior of the plate interface in downdip direction. This aseismic region at ~30 km depth that is also observed before the Illapel 2015 earthquake is likely controlled by the intersection of the continental Moho with the subducting slab.

  6. Asymmetric Earthquake Aftershock Distributions Resulting from Timing Within the Seismic Cycle

    NASA Astrophysics Data System (ADS)

    McGuire, J. J.; Collins, J. A.; Boettcher, M. S.; Roland, E. C.

    2010-12-01

    Aftershock sequences are a well documented result of changes in the crustal stress-field resulting from nearby large earthquakes, yet there is typically little (or no) constraint on the initial stress level of the “receiver fault” where the triggered aftershock occurs. Thus, many popular physical and stochastic models of aftershock triggering do not account for the absolute stress-level on a receiver fault, and the importance of this stress level (relative to a fault’s failure threshold) is not easily studied. In 2008 we recorded a series of westward propagating ruptures that marked the end of the most recent seismic cycle on the Gofar transform fault using an array of Ocean Bottom Seismometers (OBSs). The end of the 2002-2008 seismic cycle on the Gofar fault included a series of 4 major rupture events (either M6 earthquakes or large seismic swarms) that propagated ~90 km along the strike of the fault from east to west over the course of 1.5 years. Our OBS dataset covered the last 3 of these events and recorded over 200,000 microearthquakes. Each of the 3 rupture events produced a spatially asymmetric aftershock distribution. On the eastern side of each slipping zone, where the stress is lower because the fault has already ruptured in its cycle-ending event, the large rupture events do not change the seismicity-rate. In contrast, on the western side, where stress is high because the area is nearing the end of it’s seismic cycle, there is a clear increase in seismicity rate (i.e. aftershocks). This asymmetry demonstrates the importance of absolute stress-levels in earthquake triggering. This observation contrasts with the Rate-State seismicity model (Dieterich, 1994), which predicts that seismicity-rate increases will depend only on stressing-rate and the magnitude of a static stress change. Since static stress changes from large ruptures are fairly symmetric along a geometrically simple strike slip fault, like Gofar, the observed aftershock asymmetry

  7. AUSSAT mobile satellite services

    NASA Technical Reports Server (NTRS)

    Nowland, Wayne L.; Wagg, Michael; Simpson, Daniel

    1988-01-01

    An overview of AUSSAT's planned mobile satellite system is given. The development program which is being undertaken to achieve the 1992 service date is described. Both business and technical aspects of the development program are addressed.

  8. Application of Mobile Technology for Improving Expanded Program on Immunization Among Highland Minority and Stateless Populations in Northern Thailand Border

    PubMed Central

    Apidechkul, Tawatchai; Jandee, Kasemsak; Khamsiriwatchara, Amnat; Lawpoolsri, Saranath; Sawang, Surasak; Sangvichean, Aumnuyphan; Wansatid, Peerawat; Krongrungroj, Sarinya

    2015-01-01

    Background Studies of undervaccinated children of minority/stateless populations have highlighted significant barriers at individual, community, and state levels. These include geography-related difficulties, poverty, and social norms/beliefs. Objective The objective of this study was to assess project outcomes regarding immunization coverage, as well as maternal attitudes and practices toward immunization. Methods The “StatelessVac” project was conducted in Thailand-Myanmar-Laos border areas using cell phone-based mechanisms to increase immunization coverage by incorporating phone-to-phone information sharing for both identification and prevention. With limitation of the study among vulnerable populations in low-resource settings, the pre/post assessments without comparison group were conducted. Immunization coverage was collected from routine monthly reports while behavior-change outcomes were from repeat surveys. Results This study revealed potential benefits of the initiative for case identification; immunization coverage showed an improved trend. Prevention strategies were successfully integrated into the routine health care workflows of immunization activities at point-of-care. A behavior-change-communication package contributes significantly in raising both concern and awareness in relation to child care. Conclusions The mobile technology has proven to be an effective mechanism in improving a children’s immunization program among these hard-to-reach populations. Part of the intervention has now been revised for use at health centers across the country. PMID:25589367

  9. Attitudes and perceptions of patients on the kidney transplant waiting list toward mobile health–delivered physical activity programs

    PubMed Central

    Sieverdes, John C.; Raynor, Phyllis A.; Armstrong, Tracy; Jenkins, Carolyn H.; Sox, Luke R.; Treiber, Frank A.

    2016-01-01

    Context Dialysis patients’ lifestyles are associated with low levels of physical activity, increasing the chances of being removed from kidney waiting lists or dying while awaiting transplant because of increased cardiovascular risk factors and deteriorating health conditions. Personalized mobile health (mHealth) delivered programs may support their engagement in healthier lifestyles, maintain transplant eligibility, and reduce premature mortality. Objective To explore barriers and perceptions of physical activity behaviors and gauge interest in using mHealth in a physical activity wellness program for dialysis patients on the kidney transplant waiting list. Participants and Design In-depth key informant interviews were conducted with 22 randomly selected dialysis patients during dialysis treatment in an urban Southeastern coastal city. A theory-guided community-based participatory research approach was used to develop the interview content. Constructivist grounded theory guided the data analysis using NVIVO 10 (QSR Int). The 32-item checklist from the Consolidated Criteria for Reporting Qualitative Studies was used in the qualitative reporting. Results Dialysis patients had a mean age of 46 (SD, 10.7) years, 45% were female, and 82% were African American. Their mean duration on transplant waiting lists was 6.7 (SD 4.3) years, and 73% owned smartphones. After saturation was reached, predominant themes included (1) physical activity was perceived as optional, (2) social support both encouraged and limited physical activity, (3) chronic stress and coping influenced physical activity, (4) spirituality provided strength to engage in physical activity, (5) self-care management practices varied considerably, and (6) high interest (95%) for using mHealth to promote physical activity was found. Patients preferred their home and neighborhood environments to intradialytic settings for engaging in physical activity. PMID:25758797

  10. The 2004-2005 Les Saintes (French West Indies) seismic aftershock sequence observed with ocean bottom seismometers

    NASA Astrophysics Data System (ADS)

    Bazin, S.; Feuillet, N.; Duclos, C.; Crawford, W.; Nercessian, A.; Bengoubou-Valérius, M.; Beauducel, F.; Singh, S. C.

    2010-06-01

    On November 21, 2004 an Mw6.3 intraplate earthquake occurred at sea in the French Caribbean. The aftershock sequence continues to this day and is the most extensive sequence in a French territory in more than a century. We recorded aftershocks from day 25 to day 66 of this sequence, using a rapidly-deployed temporary array of ocean bottom seismometers (OBS). We invert P- and S-wave arrivals for a tomographic velocity model and improve aftershock locations. The velocity model shows anomalies related to tectonic and geologic structures beneath the Les Saintes graben. 3D relocated aftershocks outline faults whose scarps were identified as active in recent high-resolution marine data. The aftershocks distribution suggests that both the main November 21 event and its principal aftershock, on February 14, 2005, ruptured Roseau fault, which is the largest of the graben, extending from Dominica Island to the Les Saintes archipelago. Aftershocks cluster in the lower part of the Roseau fault plane (between 8 and 12.6 km depth) that did not rupture during the main event. Shallower aftershocks occur in the Roseau fault footwall, probably along smaller antithetic faults. We calculate a strong negative Vp anomaly, between 4 and 8 km depth, within the graben, along the Roseau fault plane. This low Vp anomaly is associated with a high Vp/Vs ratio and may reflect a strongly fracturated body filled with fluids. We infer from several types of observation that fault lubrication is the driving mechanism for this long-lasting aftershock sequence.

  11. The Rule of Dynamic Strain to Near Source Aftershock Distribution of the 2014, Mw 6.0, Napa (California) Earthquake

    NASA Astrophysics Data System (ADS)

    Emolo, A.; De Matteis, R.; Convertito, V.

    2015-12-01

    The 2014 Napa was recognized as a right-lateral strike-slip fault. About 400 aftershocks occurred, mainly in the near-source range, in the two months after the earthquake. They mostly occurred between 8 and 11 km depth interesting an area of about 10 km2 north-northwest-trending with respect to the mainshock hypocenter. However, the aftershock distribution was not able to constrain the mainshock fault plane. Since Parsons et al. (2014) have shown that Coulomb static stress change does not completely explain near-source aftershock distribution, we explore whether dynamic strain transfer, enhanced by source directivity, contributed to trigger the aftershock sequence. Indeed, dynamic strain transfer triggering attributes enhanced failure probabilities to increased shear stresses or strains, to permeability changes and maybe to fault weakening. In this respect, we observe that a single inverse power law fits the decay of aftershock density as function of distance from the fault plane, suggesting that dynamic stress/strain might have played a role in the aftershocks triggering. To test this hypothesis, we used Peak-Ground Velocities (PGVs) as a proxy for peak-dynamic strain/stress field, accounting for both fault finiteness and source directivity. We first use a point source to retrieve the best parameters of the directivity function from the inversion of the PGVs. Next, the same PGVs are used to jointly infer the surface fault projection and the dominant horizontal rupture direction. Finally, we map the peak-dynamic strain/stress, modified by source geometry and directivity, to resolve the relationship between the aftershocks location and the areas of large dynamic strain values. Thus, we believe that dynamic strain/stress actually contributed to the Napa aftershock distribution. Our results may help to better constrain the Napa causative fault and complement Coulomb static stress change to identify areas that will be more likely affected by aftershocks.

  12. Fault-Zone Trapped Waves from Aftershocks of the M7.2 Darfield and M6.3 Christchurch Earthquake Sequence for Document of Subsurface Damage Zones

    NASA Astrophysics Data System (ADS)

    Li, Y.; De Pascale, G. P.; Gravley, D.; Cherrington, J.; Alvarez, M. G.

    2011-12-01

    The M6.3 Christchurch earthquake struck the Canterbury region in NZ's South Island on 22 February 2011, following ~6 months after the Sept. 4, 2010 M7.1 Darfield earthquake in the same region. It has generated a significant series of aftershocks, many of which are considered big for a M6.3 earthquake. It is not know clearly whether the later M6.3 event is technically an aftershock because of its relationship to the ongoing activity since September last year, or it is a separate event, given its location on a separate fault system, a previously unknown blind fault line running 17 km south of Christchurch. In order to study the complicated subsurface structure of the damage zones caused by this sequence of earthquakes in NZ, under the support of NSF-RAPID Program, we deployed 12 PASSCAL seismographs in two ~300-m long seismic lines across the Greendale fault where the horizontal right-lateral slip of 4.5 m and vertical slip of 1.6 m were caused by the 2010 M7.2 Darfield earthquake and the aftershock zone of the M6.3 Christchurch earthquake, respectively, to record fault-zone trapped waves (FZTWs) generated by aftershocks, starting from May 5th, 2011. We have recorded the data for ~300 M>3 aftershocks with good locations and more than ~1000 small events not located yet but with good signal-to-noise ratio at these two arrays, including M5.3, M6, M5.4, M5.1 aftershocks with their clustered events at depths of 10-15 km. Preliminary examination of the waveform data shows FZTWs clearly at stations located within the 50-75-m wide rupture zone with high density of en-echelon cracks on the ground surface along the Greendale fault. 3-D finite-difference simulations of these FZTWs show a distinct low-velocity zone (LVZ) at seismogenic depth, indicating that the Greendale fault has undergone strong dynamic stresses and pervasive cracking during the 2010 M7.2 Darfield earthquake. We interpret this LVZ as being a remnant of damage zone in dynamic ruptures that accumulated damage

  13. Statistical Variability and Tokunaga Branching of Aftershock Sequences Utilizing BASS Model Simulations

    NASA Astrophysics Data System (ADS)

    Yoder, Mark R.; Van Aalsburg, Jordan; Turcotte, Donald L.; Abaimov, Sergey G.; Rundle, John B.

    2013-01-01

    Aftershock statistics provide a wealth of data that can be used to better understand earthquake physics. Aftershocks satisfy scale-invariant Gutenberg-Richter (GR) frequency-magnitude statistics. They also satisfy Omori's law for power-law seismicity rate decay and Båth's law for maximum-magnitude scaling. The branching aftershock sequence (BASS) model, which is the scale-invariant limit of the epidemic-type aftershock sequence model (ETAS), uses these scaling laws to generate synthetic aftershock sequences. One objective of this paper is to show that the branching process in these models satisfies Tokunaga branching statistics. Tokunaga branching statistics were originally developed for drainage networks and have been subsequently shown to be valid in many other applications associated with complex phenomena. Specifically, these are characteristic of a universality class in statistical physics associated with diffusion-limited aggregation. We first present a deterministic version of the BASS model and show that it satisfies the Tokunaga side-branching statistics. We then show that a fully stochastic BASS simulation gives similar results. We also study foreshock statistics using our BASS simulations. We show that the frequency-magnitude statistics in BASS simulations scale as the exponential of the magnitude difference between the mainshock and the foreshock, inverse GR scaling. We also show that the rate of foreshock occurrence in BASS simulations decays inversely with the time difference between foreshock and mainshock, an inverse Omori scaling. Both inverse scaling laws have been previously introduced empirically to explain observed foreshock statistics. Observations have demonstrated both of these scaling relations to be valid, consistent with our simulations. ETAS simulations, in general, do not generate Båth's law and do not generate inverse GR scaling.

  14. Decay of aftershock density with distance does not indicate triggering by dynamic stress.

    PubMed

    Richards-Dinger, Keith; Stein, Ross S; Toda, Shinji

    2010-09-30

    Resolving whether static or dynamic stress triggers most aftershocks and subsequent mainshocks is essential to understand earthquake interaction and to forecast seismic hazard. Felzer and Brodsky examined the distance distribution of earthquakes occurring in the first five minutes after 2 ≤ M < 3 and 3 ≤ M < 4 mainshocks and found that their magnitude M ≥ 2 aftershocks showed a uniform power-law decay with slope -1.35 out to 50 km from the mainshocks. From this they argued that the distance decay could be explained only by dynamic triggering. Here we propose an alternative explanation for the decay, and subject their hypothesis to a series of tests, none of which it passes. At distances more than 300 m from the 2 ≤ M < 3 mainshocks, the seismicity decay 5 min before the mainshocks is indistinguishable from the decay five minutes afterwards, indicating that the mainshocks have no effect at distances outside their static triggering range. Omori temporal decay, the fundamental signature of aftershocks, is absent at distances exceeding 10 km from the mainshocks. Finally, the distance decay is found among aftershocks that occur before the arrival of the seismic wave front from the mainshock, which violates causality. We argue that Felzer and Brodsky implicitly assume that the first of two independent aftershocks along a fault rupture triggers the second, and that the first of two shocks in a creep- or intrusion-driven swarm triggers the second, when this need not be the case.

  15. Implications of spatial and temporal development of the aftershock sequence for the Mw 8.3 June 9, 1994 Deep Bolivian Earthquake

    NASA Astrophysics Data System (ADS)

    Myers, Stephen C.; Wallace, Terry C.; Beck, Susan L.; Silver, Paul G.; Zandt, George; Vandecar, John; Minaya, Estela

    On June 9, 1994 the Mw 8.3 Bolivia earthquake (636 km depth) occurred in a region which had not experienced significant, deep seismicity for at least 30 years. The mainshock and aftershocks were recorded in Bolivia on the BANJO and SEDA broadband seismic arrays and on the San Calixto Network. We used the joint hypocenter determination method to determine the relative location of the aftershocks. We have identified no foreshocks and 89 aftershocks (m > 2.2) for the 20-day period following the mainshock. The frequency of aftershock occurrence decreased rapidly, with only one or two aftershocks per day occuring after day two. The temporal decay of aftershock activity is similar to shallow aftershock sequences, but the number of aftershocks is two orders of magnitude less. Additionally, a mb ∼6, apparently triggered earthquake occurred just 10 minutes after the mainshock about 330 km east-southeast of the mainshock at a depth of 671 km. The aftershock sequence occurred north and east of the mainshock and extends to a depth of 665 km. The aftershocks define a slab striking N68°W and dipping 45°NE. The strike, dip, and location of the aftershock zone are consistent with this seismicity being confined within the downward extension of the subducted Nazca plate. The location and orientation of the aftershock sequence indicate that the subducted Nazca plate bends between the NNW striking zone of deep seismicity in western Brazil and the N-S striking zone of seismicity in central Bolivia. A tear in the deep slab is not necessitated by the data. A subset of the aftershock hypocenters cluster along a subhorizontal plane near the depth of the mainshock, favoring a horizontal fault plane. The horizontal dimensions of the mainshock [Beck et al., this issue; Silver et al., 1995] and slab defined by the aftershocks are approximately equal, indicating that the mainshock ruptured through the slab.

  16. A Fluid-driven Earthquake Cycle, Omori's Law, and Fluid-driven Aftershocks

    NASA Astrophysics Data System (ADS)

    Miller, S. A.

    2015-12-01

    Few models exist that predict the Omori's Law of aftershock rate decay, with rate-state friction the only physically-based model. ETAS is a probabilistic model of cascading failures, and is sometimes used to infer rate-state frictional properties. However, the (perhaps dominant) role of fluids in the earthquake process is being increasingly realised, so a fluid-based physical model for Omori's Law should be available. In this talk, I present an hypothesis for a fluid-driven earthquake cycle where dehydration and decarbonization at depth provides continuous sources of buoyant high pressure fluids that must eventually make their way back to the surface. The natural pathway for fluid escape is along plate boundaries, where in the ductile regime high pressure fluids likely play an integral role in episodic tremor and slow slip earthquakes. At shallower levels, high pressure fluids pool at the base of seismogenic zones, with the reservoir expanding in scale through the earthquake cycle. Late in the cycle, these fluids can invade and degrade the strength of the brittle crust and contribute to earthquake nucleation. The mainshock opens permeable networks that provide escape pathways for high pressure fluids and generate aftershocks along these flow paths, while creating new pathways by the aftershocks themselves. Thermally activated precipitation then seals up these pathways, returning the system to a low-permeability environment and effective seal during the subsequent tectonic stress buildup. I find that the multiplicative effect of an exponential dependence of permeability on the effective normal stress coupled with an Arrhenius-type, thermally activated exponential reduction in permeability results in Omori's Law. I simulate this scenario using a very simple model that combines non-linear diffusion and a step-wise increase in permeability when a Mohr Coulomb failure condition is met, and allow permeability to decrease as an exponential function in time. I show very

  17. Diffusion of epicenters of earthquake aftershocks, Omori's law, and generalized continuous-time random walk models.

    PubMed

    Helmstetter, A; Sornette, D

    2002-12-01

    The epidemic-type aftershock sequence (ETAS) model is a simple stochastic process modeling seismicity, based on the two best-established empirical laws, the Omori law (power-law decay approximately 1/t(1+theta) of seismicity after an earthquake) and Gutenberg-Richter law (power-law distribution of earthquake energies). In order to describe also the space distribution of seismicity, we use in addition a power-law distribution approximately 1/r(1+mu) of distances between triggered and triggering earthquakes. The ETAS model has been studied for the last two decades to model real seismicity catalogs and to obtain short-term probabilistic forecasts. Here, we present a mapping between the ETAS model and a class of CTRW (continuous time random walk) models, based on the identification of their corresponding master equations. This mapping allows us to use the wealth of results previously obtained on anomalous diffusion of CTRW. After translating into the relevant variable for the ETAS model, we provide a classification of the different regimes of diffusion of seismic activity triggered by a mainshock. Specifically, we derive the relation between the average distance between aftershocks and the mainshock as a function of the time from the mainshock and of the joint probability distribution of the times and locations of the aftershocks. The different regimes are fully characterized by the two exponents theta and mu. Our predictions are checked by careful numerical simulations. We stress the distinction between the "bare" Omori law describing the seismic rate activated directly by a mainshock and the "renormalized" Omori law taking into account all possible cascades from mainshocks to aftershocks of aftershock of aftershock, and so on. In particular, we predict that seismic diffusion or subdiffusion occurs and should be observable only when the observed Omori exponent is less than 1, because this signals the operation of the renormalization of the bare Omori law, also at the

  18. The Mw 8.1 2014 Iquique, Chile, seismic sequence: a tale of foreshocks and aftershocks

    NASA Astrophysics Data System (ADS)

    Cesca, S.; Grigoli, F.; Heimann, S.; Dahm, T.; Kriegerowski, M.; Sobiesiak, M.; Tassara, C.; Olcay, M.

    2016-03-01

    The 2014 April 1, Mw 8.1 Iquique (Chile) earthquake struck in the Northern Chile seismic gap. With a rupture length of less than 200 km, it left unbroken large segments of the former gap. Early studies were able to model the main rupture features but results are ambiguous with respect to the role of aseismic slip and left open questions on the remaining hazard at the Northern Chile gap. A striking observation of the 2014 earthquake has been its extensive preparation phase, with more than 1300 events with magnitude above ML 3, occurring during the 15 months preceding the main shock. Increasing seismicity rates and observed peak magnitudes accompanied the last three weeks before the main shock. Thanks to the large data sets of regional recordings, we assess the precursor activity, compare foreshocks and aftershocks and model rupture preparation and rupture effects. To tackle inversion challenges for moderate events with an asymmetric network geometry, we use full waveforms techniques to locate events, map the seismicity rate and derive source parameters, obtaining moment tensors for more than 300 events (magnitudes Mw 4.0-8.1) in the period 2013 January 1-2014 April 30. This unique data set of fore- and aftershocks is investigated to distinguish rupture process models and models of strain and stress rotation during an earthquake. Results indicate that the spatial distributions of foreshocks delineated the shallower part of the rupture areas of the main shock and its largest aftershock, well matching the spatial extension of the aftershocks cloud. Most moment tensors correspond to almost pure double couple thrust mechanisms, consistent with the slab orientation. Whereas no significant differences are observed among thrust mechanisms in different areas, nor among thrust foreshocks and aftershocks, the early aftershock sequence is characterized by the presence of normal fault mechanisms, striking parallel to the trench but dipping westward. These events likely occurred

  19. The Pegasus Bay aftershock sequence of the Mw 7.1 Darfield (Canterbury), New Zealand earthquake

    NASA Astrophysics Data System (ADS)

    Ristau, John; Holden, Caroline; Kaiser, Anna; Williams, Charles; Bannister, Stephen; Fry, Bill

    2013-10-01

    The Pegasus Bay aftershock sequence is the most recent aftershock sequence of the 2010 September 3 UTC moment magnitude (Mw) 7.1 Darfield earthquake in the Canterbury region of New Zealand. The Pegasus Bay aftershock sequence began on 2011 December 23 UTC with three events of Mw 5.4-5.9 located in the offshore region of Pegasus Bay, east of Christchurch city. We present a summary of key aspects of the sequence derived using various geophysical methods. Relocations carried out using double-difference tomography show a well-defined NNE-SSW to NE-SW series of aftershocks with most of the activity occurring at depths >5 km and an average depth of ˜10 km. Regional moment tensor solutions calculated for the Pegasus Bay sequence indicate that the vast majority (45 of 53 events) are reverse-faulting events with an average P-axis azimuth of 125°. Strong-motion data inversion favours a SE-dipping fault plane for the largest event (Mw 5.9) with a slip patch of 18 km × 15 km and a maximum slip of 0.8 m at 3.5 km depth. Peak ground accelerations ranging up to 0.98 g on the vertical component were recorded during the sequence, and the largest event produced horizontal accelerations of 0.2-0.4 g in the Christchurch central business district. Apparent stress estimates for the two largest events are 1.1 MPa (Mw 5.9) and 0.2 MPa (Mw 5.8), which are compatible with global averages, although lower than other large events in the Canterbury aftershock sequence. Coulomb stress analysis indicates that previous large earthquakes in the Canterbury sequence generate Coulomb stress increases for the two events only at relatively shallow depths (3-5 km). At greater depths, Coulomb stress decreases are predicted at the locations of the two events. The trend of the aftershocks is similar to mapped reverse faults north of Christchurch, and the high number of reverse-faulting mechanisms suggests that similar reverse-faulting structures are present in the offshore region east of Christchurch.

  20. A Mobile Phone-Based, Community Health Worker Program for Referral, Follow-Up, and Service Outreach in Rural Zambia: Outcomes and Overview

    PubMed Central

    Sindano, Ntazana; Theis, Mathew; Zue, Cory; Joseph, Jessica; Chilengi, Roma; Chi, Benjamin H.; Stringer, Jeffrey S.A.; Chintu, Namwinga

    2014-01-01

    Abstract Background: Mobile health (m-health) utilizes widespread access to mobile phone technologies to expand health services. Community health workers (CHWs) provide first-level contact with health facilities; combining CHW efforts with m-health may be an avenue for improving primary care services. As part of a primary care improvement project, a pilot CHW program was developed using a mobile phone-based application for outreach, referral, and follow-up between the clinic and community in rural Zambia. Materials and Methods: The program was implemented at six primary care sites. Computers were installed at clinics for data entry, and data were transmitted to central servers. In the field, using a mobile phone to send data and receive follow-up requests, CHWs conducted household health surveillance visits, referred individuals to clinic, and followed up clinic patients. Results: From January to April 2011, 24 CHWs surveyed 6,197 households with 33,304 inhabitants. Of 15,539 clinic visits, 1,173 (8%) had a follow-up visit indicated and transmitted via a mobile phone to designated CHWs. CHWs performed one or more follow-ups on 74% (n=871) of active requests and obtained outcomes on 63% (n=741). From all community visits combined, CHWs referred 840 individuals to a clinic. Conclusions: CHWs completed all planned aspects of surveillance and outreach, demonstrating feasibility. Components of this pilot project may aid clinical care in rural settings and have potential for epidemiologic and health system applications. Thus, m-health has the potential to improve service outreach, guide activities, and facilitate data collection in Zambia. PMID:24926815

  1. The Mechanisms and Spatiotemporal Behavior of the 2011 Mw7.1 Van, Eastern Turkey Earthquake Aftershocks

    NASA Astrophysics Data System (ADS)

    Ezgi Guvercin Isik, Sezim; Ozgun Konca, A.; Karabulut, Hayrullah

    2016-04-01

    We studied the mechanisms and spatiotemporal distribution of the aftershocks of the Mw7.1 Van Earthquake, in Eastern Turkey. The 2011 Van Earthquake occurred on a E-W trending blind thrust fault in Eastern Turkey which is under N-S compression due to convergence of the Arabian plate toward the Eurasia. In this study, we relocated and studied the mechanisms of the M3.5-5.5 aftershocks from regional Pnl and surface waves using the "Cut and Paste" algorithm of Zhu and Helmberger (1996). Our results reveal that the aftershocks in the first day following the mainshock are in the vicinity of the co-seismic slip and have mostly thrust mechanism consistent with the mainshock. In the following day, a second cluster of activity at the northeast termination of the fault ( North of Lake Erçek) has started. These aftershocks have approximately N-S lineation and left lateral source mechanisms. The aftershocks surrounding the mainshock rupture are deeper (>20 km) than the aftershocks triggered on the north (<15km). We also observe strike slip earthquakes on the south of the mainshock. Both of delayed activities (north of the mainshock and south of the mainshock) are consistent with the Coulomb stress increase due to slip on the mainshock. We propose that the Van Fault is truncated by two strike-slip faults at each end, which has determined the along-strike rupture extent of the 2011 mainshock.

  2. Aftershock seismicity and tectonic setting of the 16 September 2015 Mw 8.3 Illapel earthquake, Central Chile

    NASA Astrophysics Data System (ADS)

    Lange, Dietrich; Geersen, Jacob; Barrientos, Sergio; Moreno, Marcos; Grevemeyer, Ingo; Contreras-Reyes, Eduardo; Kopp, Heidrun

    2016-06-01

    Powerful subduction zone earthquakes rupture thousands of square kilometers along continental margins but at certain locations earthquake rupture terminates. To date detailed knowledge of the parameters that govern seismic rupture and aftershocks is still incomplete. On 16 September 2015 the Mw. 8.3 Illapel earthquake ruptured a 200 km long stretch of the Central Chilean subduction zone, triggering a tsunami and causing significant damage. Here we analyze the temporal and spatial pattern of the co-seismic rupture and aftershocks in relation to the tectonic setting in the earthquake area. Aftershocks cluster around the area of maximum coseismic slip, in particular in lateral and downdip direction. During the first 24 hours after the mainshock, aftershocks migrated in both lateral directions with velocities of approximately 2.5 and 5 km/h. At the southern rupture boundary aftershocks cluster around individual subducted seamounts that are related to the downthrusting Juan Fernández Ridge. In the northern part of the rupture area aftershocks separate into an upper cluster (above 25 km depth) and a lower cluster (below 35 km depth). This dual seismic-aseismic transition in downdip direction is also observed in the interseismic period suggesting that it may represent a persistent feature for the Central Chilean subduction zone.

  3. Aftershocks of the 2010 Mw 7.2 El Mayor-Cucapah earthquake revealcomplex faulting in the Yuha Desert, California

    USGS Publications Warehouse

    Kroll, K.; Cochran, Elizabeth S.; Richards-Dinger, K.; Sumy, Danielle

    2013-01-01

    We detect and precisely locate over 9500 aftershocks that occurred in the Yuha Desert region during a 2 month period following the 4 April 2010 Mw 7.2 El Mayor-Cucapah (EMC) earthquake. Events are relocated using a series of absolute and relative relocation procedures that include Hypoinverse, Velest, and hypoDD. Location errors are reduced to ~40 m horizontally and ~120 m vertically.Aftershock locations reveal a complex pattern of faulting with en echelon fault segments trending toward the northwest, approximately parallel to the North American-Pacific plate boundary and en echelon, conjugate features trending to the northeast. The relocated seismicity is highly correlated with published surface mapping of faults that experienced triggered surface slip in response to the EMC main shock. Aftershocks occurred between 2 km and 11 km depths, consistent with previous studies of seismogenic thickness in the region. Three-dimensional analysis reveals individual and intersecting fault planes that are limited in their along-strike length. These fault planes remain distinct structures at depth, indicative of conjugate faulting, and do not appear to coalesce onto a throughgoing fault segment. We observe a complex spatiotemporal migration of aftershocks, with seismicity that jumps between individual fault segments that are active for only a few days to weeks. Aftershock rates are roughly consistent with the expected earthquake production rates of Dieterich (1994). The conjugate pattern of faulting and nonuniform aftershock migration patterns suggest that strain in the Yuha Desert is being accommodated in a complex manner.

  4. Aftershock seismicity and tectonic setting of the 2015 September 16 Mw 8.3 Illapel earthquake, Central Chile

    NASA Astrophysics Data System (ADS)

    Lange, Dietrich; Geersen, Jacob; Barrientos, Sergio; Moreno, Marcos; Grevemeyer, Ingo; Contreras-Reyes, Eduardo; Kopp, Heidrun

    2016-08-01

    Powerful subduction zone earthquakes rupture thousands of square kilometres along continental margins but at certain locations earthquake rupture terminates. To date, detailed knowledge of the parameters that govern seismic rupture and aftershocks is still incomplete. On 2015 September 16, the Mw 8.3 Illapel earthquake ruptured a 200 km long stretch of the Central Chilean subduction zone, triggering a tsunami and causing significant damage. Here, we analyse the temporal and spatial pattern of the coseismic rupture and aftershocks in relation to the tectonic setting in the earthquake area. Aftershocks cluster around the area of maximum coseismic slip, in particular in lateral and downdip direction. During the first 24 hr after the main shock, aftershocks migrated in both lateral directions with velocities of approximately 2.5 and 5 km hr-1. At the southern rupture boundary, aftershocks cluster around individual subducted seamounts that are related to the downthrusting Juan Fernández Ridge. In the northern part of the rupture area, aftershocks separate into an upper cluster (above 25 km depth) and a lower cluster (below 35 km depth). This dual seismic-aseismic transition in downdip direction is also observed in the interseismic period suggesting that it may represent a persistent feature for the Central Chilean subduction zone.

  5. Properties of foreshocks and aftershocks of the nonconservative self-organized critical Olami-Feder-Christensen model.

    PubMed

    Helmstetter, Agnès; Hergarten, Stefan; Sornette, Didier

    2004-10-01

    Following Phys. Rev. Lett. 88, 238501 (2002)] who discovered aftershocks and foreshocks in the Olami-Feder-Christensen (OFC) discrete block-spring earthquake model, we investigate to what degree the simple toppling mechanism of this model is sufficient to account for the clustering of real seismicity in time and space. We find that synthetic catalogs generated by the OFC model share many properties of real seismicity at a qualitative level: Omori's law (aftershocks) and inverse Omori's law (foreshocks), increase of the number of aftershocks and of the aftershock zone size with the mainshock magnitude. There are, however, significant quantitative differences. The number of aftershocks per mainshock in the OFC model is smaller than in real seismicity, especially for large mainshocks. We find that foreshocks in the OFC catalogs can be in large part described by a simple model of triggered seismicity, such as the epidemic-type aftershock sequence (ETAS) model. But the properties of foreshocks in the OFC model depend on the mainshock magnitude, in qualitative agreement with the critical earthquake model and in disagreement with real seismicity and with the ETAS model.

  6. The aftershock sequence of the 2015 April 25 Gorkha-Nepal earthquake

    NASA Astrophysics Data System (ADS)

    Adhikari, L. B.; Gautam, U. P.; Koirala, B. P.; Bhattarai, M.; Kandel, T.; Gupta, R. M.; Timsina, C.; Maharjan, N.; Maharjan, K.; Dahal, T.; Hoste-Colomer, R.; Cano, Y.; Dandine, M.; Guilhem, A.; Merrer, S.; Roudil, P.; Bollinger, L.

    2015-12-01

    The M 7.8 2015 April 25 Gorkha earthquake devastated the mountainous southern rim of the High Himalayan range in central Nepal. The main shock was followed by 553 earthquakes of local magnitude greater than 4.0 within the first 45 days. In this study, we present and qualify the bulletin of the permanent National Seismological Centre network to determine the spatio-temporal distribution of the aftershocks. The Gorkha sequence defines a ˜140-km-long ESE trending structure, parallel to the mountain range, abutting on the presumed extension of the rupture plane of the 1934 M 8.4 earthquake. In addition, we observe a second seismicity belt located southward, under the Kathmandu basin and in the northern part of the Mahabarat range. Many aftershocks of the Gorkha earthquake sequence have been felt by the 3 millions inhabitants of the Kathmandu valley.

  7. Implications of mainshock-aftershocks interactions during the 2013 Ebreichsdorf sequence, Austria

    NASA Astrophysics Data System (ADS)

    Tary, Jean-Baptiste; Apoloner, Maria-Theresia; Bokelmann, Götz

    2015-04-01

    The Vienna basin is a pull-apart basin located at the contact between the Alpine arc and the Eurasian plate, with the Eastern Alps to the West, the Western Carpathian to the East, the Bohemian massif to the North, and the Pannonian basin to the South. The southern border of this basin, called the Vienna Basin Fault System (VBFS), is accommodating part of the extrusion of the Pannonian basin (~1-2 mm/yr) due to the convergence between the Adriatic microplate and the Eurasian plate. The VBFS is a sinistral strike-slip fault and one of the most active fault in Austria. Along the VBFS, the seismicity is mainly concentrated in separate clusters with a spacing of approximately 20 km. In 2000 and 2013, two sequences constituted by two main shocks and 20-30 aftershocks occurred in one of these clusters located close to Ebreichsdorf, approximately 30 km south of Vienna. We focus here on the sequence of 2013 whose earthquakes were relocated using the double-difference method. The two main shocks, with local magnitudes of 4.2 and very similar focal mechanisms (N63, sinistral strike-slip), seem to be almost collocated. The aftershocks are located mainly to the northwest and at shallower depths compared with the main shocks. In order to better understand the relationships between the two main shocks and their aftershocks, we use two simple models of Coulomb failure stress to investigate possible coseismic static stress transfer between the main shocks and the aftershocks: the constant apparent friction model and the isotropic poroelastic model. The Coulomb failure stress change at the location of most aftershocks is positive but under 0.01 MPa. Aftershock triggering due to coseismic static stress is then unlikely. On the other hand, two other mechanisms could drive this sequence i.e., rapid non-linear pore pressure diffusion along the fault plane or aseismic slip. Given inter-event distances and times of ~0.5-1 km and hours to days, respectively, a high hydraulic diffusivity of

  8. No evidence of magnitude clustering in an aftershock sequence of nano- and picoseismicity.

    PubMed

    Davidsen, Jörn; Kwiatek, Grzegorz; Dresen, Georg

    2012-01-20

    One of the hallmarks of our current understanding of seismicity as highlighted by the epidemic-type-aftershock sequence model is that the magnitudes of earthquakes are independent of one another and can be considered as randomly drawn from the Gutenberg-Richter distribution. This assumption forms the basis of many approaches for forecasting seismicity rates and hazard assessment. Recently, it has been suggested that the assumption of independent magnitudes is not valid. It was subsequently argued that this conclusion was not supported by the original earthquake data from California. One of the main challenges is the lack of completeness of earthquake catalogs. Here, we study an aftershock sequence of nano- and picoseismicity as observed at the Mponeng mine, for which the issue of incompleteness is much less pronounced. We show that this sequence does not exhibit any significant evidence of magnitude correlations.

  9. Real-time forecast of aftershocks from a single seismic station signal

    NASA Astrophysics Data System (ADS)

    Lippiello, E.; Cirillo, A.; Godano, G.; Papadimitriou, E.; Karakostas, V.

    2016-06-01

    The evaluation of seismic hazard in the hours following large earthquakes is strongly affected by biases due to difficulties in determining earthquake location. This leads to the huge incompleteness of instrumental catalogs. Here we show that if, on the one hand, the overlap of aftershock coda waves hides many small events, on the other hand, it leads to a well-determined empirical law controlling the decay of the amplitude of the seismic signal at a given site. The fitting parameters of this law can be related to those controlling the temporal decay of the aftershock number, and it is then possible to obtain short-term postseismic occurrence probability from a single recorded seismic signal. We therefore present a novel procedure which, without requiring earthquake location, produces more accurate and almost real-time forecast, in a site of interest, directly from the signal of a seismic station installed at that site.

  10. Distribution of the largest event in the critical epidemic-type aftershock-sequence model

    NASA Astrophysics Data System (ADS)

    Vere-Jones, David; Zhuang, Jiancang

    2008-10-01

    This Brief Report corrects and extends the results of Zhuang and Ogata [Phys. Rev. E 73, 046134 (2006)] on the asymptotic behavior of the largest event in the epidemic-type aftershock-sequence model for earthquake occurrence. We show that, in the special case that the underlying branching process is critical, there exists a previously unnoticed mode of behavior, which occurs when the expected family size grows relatively slowly.

  11. Urban seismology - Northridge aftershocks recorded by multi-scale arrays of portable digital seismographs

    USGS Publications Warehouse

    Meremonte, M.; Frankel, A.; Cranswick, E.; Carver, D.; Worley, D.

    1996-01-01

    We deployed portable digital seismographs in the San Fernando Valley (SFV), the Los Angeles basin (LAB), and surrounding hills to record aftershocks of the 17 January 1994 Northridge California earthquake. The purpose of the deployment was to investigate factors relevant to seismic zonation in urban areas, such as site amplification, sedimentary basin effects, and the variability of ground motion over short baselines. We placed seismographs at 47 sites (not all concurrently) and recorded about 290 earthquakes with magnitudes up to 5.1 at five stations or more. We deployed widely spaced stations for profiles across the San Fernando Valley, as well as five dense arrays (apertures of 200 to 500 m) in areas of high damage, such as the collapsed Interstate 10 overpass, Sherman Oaks, and the collapsed parking garage at CalState Northridge. Aftershock data analysis indicates a correlation of site amplification with mainshock damage. We found several cases where the site amplification depended on the azimuth of the aftershock, possibly indicating focusing from basin structures. For the parking garage array, we found large ground-motion variabilities (a factor of 2) over 200-m distances for sites on the same mapped soil unit. Array analysis of the aftershock seismograms demonstrates that sizable arrivals after the direct 5 waves consist of surface waves traveling from the same azimuth as that of the epicenter. These surface waves increase the duration of motions and can have frequencies as high as about 4 Hz. For the events studied here, we do not observe large arrivals reflected from the southern edge of the San Fernando Valley.

  12. Distribution of the largest event in the critical epidemic-type aftershock-sequence model.

    PubMed

    Vere-Jones, David; Zhuang, Jiancang

    2008-10-01

    This Brief Report corrects and extends the results of Zhuang and Ogata [Phys. Rev. E 73, 046134 (2006)] on the asymptotic behavior of the largest event in the epidemic-type aftershock-sequence model for earthquake occurrence. We show that, in the special case that the underlying branching process is critical, there exists a previously unnoticed mode of behavior, which occurs when the expected family size grows relatively slowly.

  13. Seismological aspects of the 27 June 2015 Gulf of Aqaba earthquake and its sequence of aftershocks

    NASA Astrophysics Data System (ADS)

    Abd el-aal, Abd el-aziz Khairy; Badreldin, Hazem

    2016-07-01

    On 27 June 2015, a moderate earthquake with magnitude Mb 5.2 struck the Gulf of Aqaba near Nuweiba City. This event was instrumentally recorded by the Egyptian National Seismic Network (ENSN) and many other international seismological centres. The event was felt in all the cities on the Gulf of Aqaba, as well as Suez City, Hurghada City, the greater Cairo Metropolitan Area, Israel, Jordan and the north-western part of Saudi Arabia. No casualties were reported, however. Approximately 95 aftershocks with magnitudes ranging from 0.7 to 4.2 were recorded by the ENSN following the mainshock. In the present study, the source characteristics of both the mainshock and the aftershocks were estimated using the near-source waveform data recorded by the very broadband stations of the ENSN, and these were validated by the P-wave polarity data from short period stations. Our analysis reveals that an estimated seismic moment of 0.762 × 1017 Nm was released, corresponding to a magnitude of Mw 5.2, a focal depth of 14 km, a fault radius of 0.72 km and a rupture area of approximately 1.65 km2. Monitoring the sequence of aftershocks reveals that they form a cluster around the mainshock and migrated downwards in focal depth towards the west. We compared the results we obtained with the published results from the international seismological centres. Our results are more realistic and accurate, in particular with respect to the epicenteral location, magnitude and fault plane solution which are in accordance with the hypocentre distribution of the aftershocks.

  14. Identification of a major segment boundary between two megathrust subduction zone earthquakes from aftershock seismicity

    NASA Astrophysics Data System (ADS)

    Sobiesiak, M.; Victor, P.; Eggert, S.

    2009-04-01

    Aftershock seismicity is commonly used to characterize the extent of rupture planes of megathrust earthquakes. From unique datasets, covering the two adjacent fault planes of the Mw 8.0, 1995, Antofagasta and the Mw 7.7, 2007, Tocopilla earthquakes, we were able to identify a segment boundary (SB), located beneath Mejillones Peninsula. This segment boundary hosted the onset of the Antofagasta rupture and constituted the end of the Tocopilla rupture plane. The data recorded during the mission of the German Task Force for Earthquakes after the 2007 Tocopilla earthquake is supporting our observations regarding the northern part of the SB. 34 seismological stations registered the aftershocks from November 2007 until May 2008. First hypocenter determinations show that the aftershock sequences of both events meet along this E-W oriented segment boundary. The segment boundary is furthermore conformed by the historic record of megathrust events. Evidence for long term persistency of this SB comes from geological observations as differential uplift rates across the boundary and different fault patterns. Geomorpholocical analysis defines a topographic anomaly ~ 20 km wide and oriented along strike the SB..The main shock hypocenter determinations (NEIC, local network, ISC) which are related to the start of the rupture are all located in this zone. The SB is further characterized by intermediate b-values derived from a spatial b-value study of the Antofagasta fault plane and hosts several elongated clusters of aftershock seismicity. A detailed study of the focal mechanism solutions in one of these clusters showed a number of aligned strike slip events with one E-W striking nodal plane having a strike angle which is similar to the angle of subduction obliquity of the oceanic Nazca plate in this area. In further investigations we will search for detailed information on the nature and dynamics of processes along such a segment boundary, their meaning for the initiation of large

  15. Delineating complex spatiotemporal distribution of earthquake aftershocks: an improved Source-Scanning Algorithm

    NASA Astrophysics Data System (ADS)

    Liao, Yen-Che; Kao, Honn; Rosenberger, Andreas; Hsu, Shu-Kun; Huang, Bor-Shouh

    2012-06-01

    Conventional earthquake location methods depend critically on the correct identification of seismic phases and their arrival times from seismograms. Accurate phase picking is particularly difficult for aftershocks that occur closely in time and space, mostly because of the ambiguity of correlating the same phase at different stations. In this study, we introduce an improved Source-Scanning Algorithm (ISSA) for the purpose of delineating the complex distribution of aftershocks without time-consuming and labour-intensive phase-picking procedures. The improvements include the application of a ground motion analyser to separate P and S waves, the automatic adjustment of time windows for 'brightness' calculation based on the scanning resolution and a modified brightness function to combine constraints from multiple phases. Synthetic experiments simulating a challenging scenario are conducted to demonstrate the robustness of the ISSA. The method is applied to a field data set selected from the ocean-bottom-seismograph records of an offshore aftershock sequence southwest of Taiwan. Although visual inspection of the seismograms is ambiguous, our ISSA analysis clearly delineates two events that can best explain the observed waveform pattern.

  16. Aftershocks of the western Argentina (Caucete) earthquake of 23 November 1977: some tectonic implications

    USGS Publications Warehouse

    Langer, C.J.; Bollinger, G.A.

    1988-01-01

    An aftershock survey, using a network of eight portable and two permanent seismographs, was conducted for the western Argentina (Caucete) earthquake (MS 7.3) of November 23, 1977. Monitoring began December 6, almost 2 weeks after the main shock and continued for 11 days. The data set includes 185 aftershock hypocenters that range in the depth from near surface to more than 30 km. The spatial distribution of those events occupied a volume of about 100 km long ??50 km wide ??30 km thick. The volumnar nature of the aftershock distribution is interpreted to be a result of a bimodal distribution of foci that define east- and west-dipping planar zones. Efforts to select which of those zones was associated with the causal faulting include special attention to the determination of the mainshock focal depth and dislocation theory modeling of the coseismic surface deformation in the epicentral region. Our focal depth (25-35 km) and modeling studies lead us to prefer an east-dipping plane as causal. A previous interpretation by other investigators used a shallower focal depth (17 km) and similar modeling calculations in choosing a west-dipping plane. Our selection of the east-dipping plane is physically more appealing because it places fault initiation at the base of the crustal seismogenic layer (rather than in the middle of that layer) which requires fault propagation to be updip (rather than downdip). ?? 1988.

  17. Long aftershock sequences within continents and implications for earthquake hazard assessment.

    PubMed

    Stein, Seth; Liu, Mian

    2009-11-01

    One of the most powerful features of plate tectonics is that the known plate motions give insight into both the locations and average recurrence interval of future large earthquakes on plate boundaries. Plate tectonics gives no insight, however, into where and when earthquakes will occur within plates, because the interiors of ideal plates should not deform. As a result, within plate interiors, assessments of earthquake hazards rely heavily on the assumption that the locations of small earthquakes shown by the short historical record reflect continuing deformation that will cause future large earthquakes. Here, however, we show that many of these recent earthquakes are probably aftershocks of large earthquakes that occurred hundreds of years ago. We present a simple model predicting that the length of aftershock sequences varies inversely with the rate at which faults are loaded. Aftershock sequences within the slowly deforming continents are predicted to be significantly longer than the decade typically observed at rapidly loaded plate boundaries. These predictions are in accord with observations. So the common practice of treating continental earthquakes as steady-state seismicity overestimates the hazard in presently active areas and underestimates it elsewhere. PMID:19890328

  18. Can current New Madrid seismicity be explained as a decaying aftershock sequence?

    NASA Astrophysics Data System (ADS)

    Page, M. T.; Hough, S. E.; Felzer, K. R.

    2012-12-01

    It has been suggested that continuing seismicity in the New Madrid, central U.S. region is primarily composed of the continuing long-lived aftershock sequence of the 1811-1812 sequence, and thus cannot be taken as an indication of present-day strain accrual in the region. We examine historical and instrumental seismicity in the New Madrid region to determine if such a model is feasible given 1) the observed protracted nature of past New Madrid sequences, with multiple mainshocks with apparently similar magnitudes; 2) the rate of historically documented early aftershocks from the 1811-1812 sequence; and 3) plausible mainshock magnitudes and aftershock-productivity parameters. We use ETAS modeling to search for sub-critical sets of direct Omori parameters that are consistent with all of these datasets, given a realistic consideration of their uncertainties, and current seismicity in the region. The results of this work will help to determine whether or not future sequences are likely to be clusters of events like those in the past, a key issue for earthquake response planning.

  19. Long aftershock sequences within continents and implications for earthquake hazard assessment.

    PubMed

    Stein, Seth; Liu, Mian

    2009-11-01

    One of the most powerful features of plate tectonics is that the known plate motions give insight into both the locations and average recurrence interval of future large earthquakes on plate boundaries. Plate tectonics gives no insight, however, into where and when earthquakes will occur within plates, because the interiors of ideal plates should not deform. As a result, within plate interiors, assessments of earthquake hazards rely heavily on the assumption that the locations of small earthquakes shown by the short historical record reflect continuing deformation that will cause future large earthquakes. Here, however, we show that many of these recent earthquakes are probably aftershocks of large earthquakes that occurred hundreds of years ago. We present a simple model predicting that the length of aftershock sequences varies inversely with the rate at which faults are loaded. Aftershock sequences within the slowly deforming continents are predicted to be significantly longer than the decade typically observed at rapidly loaded plate boundaries. These predictions are in accord with observations. So the common practice of treating continental earthquakes as steady-state seismicity overestimates the hazard in presently active areas and underestimates it elsewhere.

  20. Applying Error Diagram for Evaluating Spatial Forecasting Model of Large Aftershocks

    NASA Astrophysics Data System (ADS)

    Shebalin, Peter; Sergey, Baranov

    2016-04-01

    Difficulty of use in practice the forecasting result formulated in probability terms is well known in statistical seismology. Small values of probability of earthquake occurrence cannot be directly used for decision making to reduce losses due to seismic hazard. In this research we suggest a technique for applying Molchan's error diagram to evaluate a model of seismic hazard forecasting and make practical recommendation, applied specifically to the hazard after large earthquakes. We illustrate the suggested technique by example of evaluating retrospective forecast of an area where one can expect strong aftershock (M6+). The forecast model is based on data for 12 hours after the mainshock. We found an optimal variant among many tested by minimizing the rate of missed targets (strong aftershock) and the rate of alarm space as a loss function. Analyzing the error diagram, we suggest these three forecast strategies: "soft", "neutral", and 'hard", giving different size of the alarm area, where one may expect strong aftershocks. The suggested technique can be used for making decision at various conditions to reduce losses due to seismic hazard after a strong earthquake. This research was carried out at the expense of the Russian Science Foundation (Project Nu 16-17-00093).

  1. Main shock and aftershock records of the 1999 Izmit and Duzce, Turkey earthquakes

    USGS Publications Warehouse

    Celebi, M.; Akkar, Sinan; Gulerce, U.; Sanli, A.; Bundock, H.; Salkin, A.

    2001-01-01

    The August 17, 1999 Izmit (Turkey) earthquake (Mw=7.4) will be remembered as one of the largest earthquakes of recent times that affected a large urban environment (U.S. Geological Survey, 1999). This significant event was followed by many significant aftershocks and another main event (Mw=7.2) that occurred on November 12, 1999 near Duzce (Turkey). The shaking that caused the widespread damage and destruction was recorded by a handful of accelerographs (~30) in the earthquake area operated by different networks. The characteristics of these records show that the recorded peak accelerations, shown in Figure 1, even those from near field stations, are smaller than expected (Çelebi, 1999, 2000). Following this main event, several organizations from Turkey, Japan, France and the USA deployed temporary accelerographs and other aftershock recording hardware. Thus, the number of recording stations in the earthquake affected area was quadrupled (~130). As a result, as seen in Figure 2, smaller magnitude aftershocks yielded larger peak accelerations, indicating that because of the sparse networks, recording of larger motions during the main shock of August 17, 1999 were possibly missed.

  2. Spatial/Temporal interdependence of aftershocks following the 10/31/2001 M5.1 Anza Earthquake

    NASA Astrophysics Data System (ADS)

    Kilb, D.; Martynov, V.; Vernon, F. L.

    2004-12-01

    On 10/31/2001, a M5.1 earthquake occurred in the middle of the ANZA network (7 24-bit broadband stations were within 20 km of the epicenter) that spans the San Jacinto fault zone in southern California. A high pass filter (f > 1.0 Hz) was used to identify seismic arrival times of the aftershocks and in turn determine the aftershock locations. In this way, we cataloged 599 events (0< M < 2.5) in the initial 2 hours of this sequence and 4500 aftershocks within the first 2 months, complete to M ≈ 0.0. Here, we study three different temporal/spatial features found in these data. (1) Initially we suspected earthquakes within the region of the mainshock had a bimodal distribution of earthquake magnitudes (peaks at M=0.1 and M=1.5); however, we found this distribution was an artifact of the spatial recording capabilities of small magnitude aftershocks. (2) In the original aftershock locations we found two linear voids in seismicity (trends ˜N45W and ˜N45E) in the primary aftershock cluster forming an X pattern. This is not likely caused by the number of significant digits in the location algorithm because these voids do not follow individual latitude or longitude lines, nor is this likely due to recording inaccuracies because the network coverage of the region is more than optimal. We are investigating other causes of these voids. (3) In the broadband data, we found only one detectable aftershock in the first 2 minutes of the continuous waveforms; yet on the short period records at one of the closest stations, TRO, we can identify an additional event at 15 seconds into the sequence. To quantify our detection capabilities, we estimate when aftershocks of different magnitudes can be identified within the mainshock coda. We are fairly confident that \\> M 1.5 events 45 seconds or longer after the mainshock should be detectable, which suggests that the lack of seismicity in the 45 second-2.0 minute range is potentially real. This non-zero lag-time between the mainshock

  3. Aftershock Seismicity of the 27 February 2010 Mw 8.8 Maule Earthquake Rupture Zone

    NASA Astrophysics Data System (ADS)

    Lange, D.; Tilmann, F. J.; Barrientos, S. E.; Bataille, K.; Beck, S. L.; Bernard, P.; Campos, J. A.; Comte, D.; Haberland, C. A.; Heit, B.; Methe, P.; Peyrat, S.; Rietbrock, A.; Roecker, S.; Schurr, B.; Vilotte, J.

    2010-12-01

    On 27 February 2010 the Mw 8.8 Maule earthquake in Central Chile ruptured a well known seismic gap, which last broke in 1835. Shortly after the mainshock Chilean agencies (UC Santiago, UC Concepción) and the international seismological community (USA (IRIS), France (IPGP), UK (University of Liverpool), Germany (GFZ)) installed a total of 142 portable seismic stations along the whole rupture zone in order to capture the aftershock activity. Here, we present the aftershock distribution based on automatic detection algorithms and picking engines (MPX; STA/LTA) which will be calibrated with a subset of manually picked events. Initial processing of 70 days of continuous data (20 March until 29 May 2010) from IRIS and GFZ stations resulted in the detection of well over 30,000 events. Of these, we consider a higher quality subset of 12,824 hypocentres based on more than 12 automatically picked P arrivals. Because picking errors can be large for the smaller arrivals, the depths of located events are not always reliable, particularly far from the coast. Nevertheless, a few first order features can be identified: 1.) A pronounced cluster of seismicity is apparent at 25-35 km depth and 50-120 km perpendicular distance from the trench (with some NS variation). 2.) A secondary band of seismicity can be identified at 40-50 km depth and ~150-160 km perpendicular trench distance and between 34° and 37°S. Although the secondary band lies along the continuation of the primary one, it is clearly separated from it by a gap with sparse seismicity. It is not yet possible to state whether these events occurred on the plate interface or in the downgoing plate. 3.) Intense crustal seismicity is found in the region of Pichilemu. This region hosted the strongest aftershock (Mw=6.9), a normal faulting event with NW strike. The aftershocks extend from the plate interface to the surface and are aligned on a NNW-SSE oriented band in map view. 4.) An isolated shallow cluster of crustal

  4. The Aftershock Analyses of 27 February 2010 Chile M=8.8 Mega Earthquake

    NASA Astrophysics Data System (ADS)

    Lee, C.-S.; Klingelhoefer, F.; Gutscher, M.; Miller, M.; Gallardo, V.

    2012-04-01

    In 1960, the biggest earthquake (M=9.5), the human ever recorded event, occurred in south Chile. Subsequently several mega earthquake (M >8) occurred, including the M=8.8 earthquake in 2010. This reflects that an incomplete release of tectonic energy exists in the Chile subduction system. The west coast of Chile is a long convergence plate boundary between the Nazca and the South American plate. The Nazca Plate subducts beneath the South American Plate toward the northeast with a convergence rate of about 6.5 cm/year, accumulating the stress in the lower part of the subducted plate to some extent resulting in destructive ruptures. On 27 February 2010, the Maule mega earthquake (M=8.8) occurred offshore central Chile. The epicenter (35.9° S, 72.73° W) is located at 115 km, NE of Concepción, the second biggest city in Chile. The main shock was a thrust-type subduction earthquake where the Nazca Plate subducted into the South America Plate (the Chile subduction system). The focal depth of main shock is 35 km which caused more than 500-km long rupture in the accretionary prism and produced a destructive tsunami of more than 20 m. It killed several hundreds of people and damaged countless buildings. Even up to today, aftershocks and volcanic activities continue to occur in this region. During May-August of last year, we shipped 20 OBSs to Chile and conducted two aftershock surveys in the tsunami-affected area. The OBSs recorded more than 4,000 aftershock events, magnitude from M=6.0 to 1.0. Results show that the aftershock data were concentrated into two masses: the landward side of the paleo-accretionary prism and the seaward side of the subducting plate, leaving a "white zone" in the frontal accretionary prisms. Both data sets consistently indicate the same result. The angle between the paleo-accretionary prism and the subduction plate seems to be greater than that of the frontal-accretionary prism. We suggest that the greater of the splay fault angle the higher

  5. Focal Depth of the WenChuan Earthquake Aftershocks from modeling of Seismic Depth Phases

    NASA Astrophysics Data System (ADS)

    Luo, Y.; Zeng, X.; Chong, J.; Ni, S.; Chen, Y.

    2008-12-01

    After the 05/12/2008 great WenChuan earthquake in Sichuan Province of China, tens of thousands earthquakes occurred with hundreds of them stronger than M4. Those aftershocks provide valuable information about seismotectonics and rupture processes for the mainshock, particularly accurate spatial distribution of aftershocks is very informational for determining rupture fault planes. However focal depth can not be well resolved just with first arrivals recorded by relatively sparse network in Sichuan Province, therefore 3D seismicity distribution is difficult to obtain though horizontal location can be located with accuracy of 5km. Instead local/regional depth phases such as sPmP, sPn, sPL and teleseismic pP,sP are very sensitive to depth, and be readily modeled to determine depth with accuracy of 2km. With reference 1D velocity structure resolved from receiver functions and seismic refraction studies, local/regional depth phases such as sPmP, sPn and sPL are identified by comparing observed waveform with synthetic seismograms by generalized ray theory and reflectivity methods. For teleseismic depth phases well observed for M5.5 and stronger events, we developed an algorithm in inverting both depth and focal mechanism from P and SH waveforms. Also we employed the Cut and Paste (CAP) method developed by Zhao and Helmberger in modeling mechanism and depth with local waveforms, which constrains depth by fitting Pnl waveforms and the relative weight between surface wave and Pnl. After modeling all the depth phases for hundreds of events , we find that most of the M4 earthquakes occur between 2-18km depth, with aftershocks depth ranging 4-12km in the southern half of Longmenshan fault while aftershocks in the northern half featuring large depth range up to 18km. Therefore seismogenic zone in the northern segment is deeper as compared to the southern segment. All the aftershocks occur in upper crust, given that the Moho is deeper than 40km, or even 60km west of the

  6. Mobile Goes Mainstream

    ERIC Educational Resources Information Center

    Eisele-Dyrli, Kurt

    2011-01-01

    Mobile learning--the use of mobile devices for educational purposes by students--is rapidly moving from an experimental initiative by a few innovative districts over the last five years to a broadly accepted concept in K12. The latest research and surveys, results of pilot programs, and analysis of trends in both public education and the broader…

  7. Automatic Classification of Extensive Aftershock Sequences Using Empirical Matched Field Processing

    NASA Astrophysics Data System (ADS)

    Gibbons, Steven J.; Harris, David B.; Kværna, Tormod; Dodge, Douglas A.

    2013-04-01

    The aftershock sequences that follow large earthquakes create considerable problems for data centers attempting to produce comprehensive event bulletins in near real-time. The greatly increased number of events which require processing can overwhelm analyst resources and reduce the capacity for analyzing events of monitoring interest. This exacerbates a potentially reduced detection capability at key stations, due the noise generated by the sequence, and a deterioration in the quality of the fully automatic preliminary event bulletins caused by the difficulty in associating the vast numbers of closely spaced arrivals over the network. Considerable success has been enjoyed by waveform correlation methods for the automatic identification of groups of events belonging to the same geographical source region, facilitating the more time-efficient analysis of event ensembles as opposed to individual events. There are, however, formidable challenges associated with the automation of correlation procedures. The signal generated by a very large earthquake seldom correlates well enough with the signals generated by far smaller aftershocks for a correlation detector to produce statistically significant triggers at the correct times. Correlation between events within clusters of aftershocks is significantly better, although the issues of when and how to initiate new pattern detectors are still being investigated. Empirical Matched Field Processing (EMFP) is a highly promising method for detecting event waveforms suitable as templates for correlation detectors. EMFP is a quasi-frequency-domain technique that calibrates the spatial structure of a wavefront crossing a seismic array in a collection of narrow frequency bands. The amplitude and phase weights that result are applied in a frequency-domain beamforming operation that compensates for scattering and refraction effects not properly modeled by plane-wave beams. It has been demonstrated to outperform waveform correlation as a

  8. Constraints on Dynamic Triggering from very Short term Microearthquake Aftershocks at Parkfield

    NASA Astrophysics Data System (ADS)

    Ampuero, J.; Rubin, A.

    2004-12-01

    The study of microearthquakes helps bridge the gap between laboratory experiments and data from large earthquakes, the two disparate scales that have contributed so far to our understanding of earthquake physics. Although they are frequent, microearthquakes are difficult to analyse. Applying high precision relocation techniques, Rubin and Gillard (2000) observed a pronounced asymmetry in the spatial distribution of the earliest and nearest aftershocks of microearthquakes along the San Andreas fault (they occur more often to the NW of the mainshock). It was suggested that this could be related to the velocity contrast across the fault. Preferred directivity of dynamic rupture pulses running along a bimaterial interface (to the SE in the case of the SAF) is expected on theoretical grounds. Our numerical simulations of crack-like rupture on such interfaces show a pronounced asymmetry of the stress histories beyond the rupture ends, and suggest two possible mechanisms for the observed asymmetry: First, that it results from an asymmmetry in the static stress field following arrest of the mainshock (closer to failure to the NW), or second, that it is due to a short-duration tensile pulse that propagates to the SE, which could reduce the number of aftershocks to the SE by dynamic triggering of any nucleation site close enough to failure to have otherwise produced an aftershock. To distinguish betwen these mechanisms we need observations of dynamic triggering in microseismicity. For small events triggered at a distance of some mainshock radii, triggering time scales are so short that seismograms of both events overlap. To detect the occurrence of compound events and very short term aftershocks in the HRSN Parkfield archived waveforms we have developed an automated search algorithm based on empirical Green's function (EGF) deconvolution. Optimal EGFs are first selected by the coherency of the cross-component convolution with respect to the target event. Then Landweber

  9. The Mobile Manual Arts Unit in South-West Queensland. Priority Country Area Program Evaluation Series: Report No. 11.

    ERIC Educational Resources Information Center

    Fowler, Clifford F.; Peters, Joanne

    Begun in 1978 to bring manual arts experience to children in Queensland's "disadvantaged country areas," the Mobile Manual Arts Unit by the end of the 1980 school year had visited 16 separate locations, involving 25 different schools. A total of 727 students had participated (out of a target population of 992 pupils) and a total of 259 contact…

  10. Mississippi Labor Mobility Demonstration Project--Relocating the Unemployed: Evaluation and Policy Implications for a National Program.

    ERIC Educational Resources Information Center

    Speight, John F.; And Others

    The report provides a detailed review of the seven and one-half year Mississippi Labor Mobility Project, STAR, Inc., whose operations and research concerned the utility and feasibility of subsidizing worker relocation assistance to the unemployed/underemployed poor for the purposes of improving their economic and social opportunities. Almost 2,500…

  11. ACTS mobile SATCOM experiments

    NASA Technical Reports Server (NTRS)

    Abbe, Brian S.; Frye, Robert E.; Jedrey, Thomas C.

    1993-01-01

    Over the last decade, the demand for reliable mobile satellite communications (satcom) for voice, data, and video applications has increased dramatically. As consumer demand grows, the current spectrum allocation at L-band could become saturated. For this reason, NASA and the Jet Propulsion Laboratory are developing the Advanced Communications Technology Satellites (ACTS) mobile terminal (AMT) and are evaluating the feasibility of K/Ka-band (20/30 GHz) mobile satcom to meet these growing needs. U.S. industry and government, acting as co-partners, will evaluate K/Ka-band mobile satcom and develop new technologies by conducting a series of applications-oriented experiments. The ACTS and the AMT testbed will be used to conduct these mobile satcom experiments. The goals of the ACTS Mobile Experiments Program and the individual experiment configurations and objectives are further presented.

  12. Mobile satellite service for Canada

    NASA Technical Reports Server (NTRS)

    Sward, David

    1988-01-01

    The Mobile Satellite (MSAT) system and a special program designed to provide interim mobile satellite services (IMSS) during the construction phase of MSAT are described. A mobile satellite system is a key element in extending voice and and data telecommunications to all Canadians.

  13. Full waveform modelling using the VERCE platform - application to aftershock seismicity in the Chile subduction zone

    NASA Astrophysics Data System (ADS)

    Garth, Thomas; Rietbrock, Andreas; Hicks, Steve; Fuenzalida Velasco, Amaya; Casarotti, Emanuele; Spinuso, Alessandro

    2015-04-01

    The VERCE platform is an online portal that allows full waveform simulations to be run for any region where a suitable velocity model exists. We use this facility to simulate the waveforms from aftershock earthquakes from the 2014 Pisagua earthquake, and 2010 Maule earthquake that occurred at the subduction zone mega thrust in Northern and Central Chile respectively. Simulations are performed using focal mechanisms from both global earthquake catalogues, and regional earthquake catalogues. The VERCE platform supports specFEM Cartesian, and simulations are run using meshes produced by CUBIT. The full waveform modelling techniques supported on the VERCE platform are used to test the validity of a number of subduction zone velocity models from the Chilean subduction zone. For the Maule earthquake we use a 2D and 3D travel time tomography model of the rupture area (Hicks et al. 2011; 2014). For the Pisagua earthquake we test a 2D/3D composite velocity model based on tomographic studies of the region (e.g. Husen et al. 2000, Contreyes-Reyes et al. 2012) and slab1.0 (Hayes et al. 2012). Focal mechanisms from the cGMT catalogue and local focal mechanisms calculated using ISOLA (e.g. Agurto et al. 2012) are used in the simulations. The waveforms produced are directly compared to waveforms recorded on the temporary deployment for the Maule earthquake aftershocks, and waveforms recorded on the IPOC network for the Pisagua earthquake aftershocks. This work demonstrates how the VERCE platform allows waveforms from the full 3D simulations to be easily produced, allowing us to quantify the validity of both the velocity model and the source mechanisms. These simulations therefore provide an independent test of the velocity models produced synthetically and by travel time tomography studies. Initial results show that the waveform is reasonably well reproduced in the 0.05 - 0.25 frequency band using a refined 3D travel time tomography, and locally calculated focal mechanisms.

  14. An Autonomous System for Grouping Events in a Developing Aftershock Sequence

    SciTech Connect

    Harris, D. B.; Dodge, D. A.

    2011-03-22

    We describe a prototype detection framework that automatically clusters events in real time from a rapidly unfolding aftershock sequence. We use the fact that many aftershocks are repetitive, producing similar waveforms. By clustering events based on correlation measures of waveform similarity, the number of independent event instances that must be examined in detail by analysts may be reduced. Our system processes array data and acquires waveform templates with a short-term average (STA)/long-term average (LTA) detector operating on a beam directed at the P phases of the aftershock sequence. The templates are used to create correlation-type (subspace) detectors that sweep the subsequent data stream for occurrences of the same waveform pattern. Events are clustered by association with a particular detector. Hundreds of subspace detectors can run in this framework a hundred times faster than in real time. Nonetheless, to check the growth in the number of detectors, the framework pauses periodically and reclusters detections to reduce the number of event groups. These groups define new subspace detectors that replace the older generation of detectors. Because low-magnitude occurrences of a particular signal template may be missed by the STA/LTA detector, we advocate restarting the framework from the beginning of the sequence periodically to reprocess the entire data stream with the existing detectors. We tested the framework on 10 days of data from the Nevada Seismic Array (NVAR) covering the 2003 San Simeon earthquake. One hundred eighty-four automatically generated detectors produced 676 detections resulting in a potential reduction in analyst workload of up to 73%.

  15. Estimating seismic site response in Christchurch City (New Zealand) from dense low-cost aftershock arrays

    USGS Publications Warehouse

    Kaiser, Anna E.; Benites, Rafael A.; Chung, Angela I.; Haines, A. John; Cochran, Elizabeth S.; Fry, Bill

    2011-01-01

    The Mw 7.1 September 2010 Darfield earthquake, New Zealand, produced widespread damage and liquefaction ~40 km from the epicentre in Christchurch city. It was followed by the even more destructive Mw 6.2 February 2011 Christchurch aftershock directly beneath the city’s southern suburbs. Seismic data recorded during the two large events suggest that site effects contributed to the variations in ground motion observed throughout Christchurch city. We use densely-spaced aftershock recordings of the Darfield earthquake to investigate variations in local seismic site response within the Christchurch urban area. Following the Darfield main shock we deployed a temporary array of ~180 low-cost 14-bit MEMS accelerometers linked to the global Quake-Catcher Network (QCN). These instruments provided dense station coverage (spacing ~2 km) to complement existing New Zealand national network strong motion stations (GeoNet) within Christchurch city. Well-constrained standard spectral ratios were derived for GeoNet stations using a reference station on Miocene basalt rock in the south of the city. For noisier QCN stations, the method was adapted to find a maximum likelihood estimate of spectral ratio amplitude taking into account the variance of noise at the respective stations. Spectral ratios for QCN stations are similar to nearby GeoNet stations when the maximum likelihood method is used. Our study suggests dense low-cost accelerometer aftershock arrays can provide useful information on local-scale ground motion properties for use in microzonation. Preliminary results indicate higher amplifications north of the city centre and strong high-frequency amplification in the small, shallower basin of Heathcote Valley.

  16. An aeronautical mobile satellite experiment

    NASA Technical Reports Server (NTRS)

    Jedrey, T. C.; Dessouky, K. I.; Lay, N. E.

    1990-01-01

    The various activities and findings of a NASA/FAA/COMSAT/INMARSAT collaborative aeronautical mobile satellite experiment are detailed. The primary objective of the experiment was to demonstrate and evaluate an advanced digital mobile satellite terminal developed at the Jet Propulsion Laboratory under the NASA Mobile Satellite Program. The experiment was a significant milestone for NASA/JPL, since it was the first test of the mobile terminal in a true mobile satellite environment. The results were also of interest to the general mobile satellite community because of the advanced nature of the technologies employed in the terminal.

  17. Development and application of a specially designed heating system for temperature-programmed high-performance liquid chromatography using subcritical water as the mobile phase.

    PubMed

    Teutenberg, T; Goetze, H-J; Tuerk, J; Ploeger, J; Kiffmeyer, T K; Schmidt, K G; Kohorst, W gr; Rohe, T; Jansen, H-D; Weber, H

    2006-05-01

    A specially designed heating system for temperature-programmed HPLC was developed based on experimental measurements of eluent temperature inside a stainless steel capillary using a very thin thermocouple. The heating system can be operated at temperatures up to 225 degrees C and consists of a preheating, a column heating and a cooling unit. Fast cycle times after a temperature gradient can be realized by an internal silicone oil bath which cools down the preheating and column heating unit. Long-term thermal stability of a polybutadiene-coated zirconium dioxide column has been evaluated using a tubular oven in which the column was placed. The packing material was stable after 50h of operation at 185 degrees C. A mixture containing four steroids was separated at ambient conditions using a mobile phase of 25% acetonitrile:75% deionized water and a mobile phase of pure deionized water at 185 degrees C using the specially designed heating system and the PBD column. Analysis time could be drastically reduced from 17 min at ambient conditions and a flow rate of 1 mL/min to only 1.2 min at 185 degrees C and a flow rate of 5 mL/min. At these extreme conditions, no thermal mismatch was observed and peaks were not distorted, thus underlining the performance of the developed heating system. Temperature programming was performed by separating cytostatic and antibiotic drugs with a temperature gradient using only water as the mobile phase. In contrast to an isocratic elution of this mixture at room temperature, overall analysis time could be reduced two-fold from 20 to 10 min. PMID:16530210

  18. Precise aftershock distribution of the 2011 off the Pacific coast of Tohoku Earthquake revealed by an ocean-bottom seismometer network

    NASA Astrophysics Data System (ADS)

    Shinohara, Masanao; Machida, Yuya; Yamada, Tomoaki; Nakahigashi, Kazuo; Shinbo, Takashi; Mochizuki, Kimihiro; Murai, Yoshio; Hino, Ryota; Ito, Yoshihiro; Sato, Toshinori; Shiobara, Hajime; Uehira, Kenji; Yakiwara, Hiroshi; Obana, Koichiro; Takahashi, Narumi; Kodaira, Shuichi; Hirata, Kenji; Tsushima, Hiroaki; Iwasaki, Takaya

    2012-12-01

    The 2011 off the Pacific coast of Tohoku Earthquake occurred at the plate boundary between the Pacific plate and the landward plate on March 11, 2011, and had a magnitude of 9. Many aftershocks occurred following the mainshock. Obtaining a precise aftershock distribution is important for understanding the mechanism of earthquake generation. In order to study the aftershock activity of this event, we carried out extensive sea-floor aftershock observations using more than 100 ocean-bottom seismometers just after the mainshock. A precise aftershock distribution for approximately three months over the whole source area was obtained from the observations. The aftershocks form a plane dipping landward over the whole area, nevertheless the epicenter distribution is not uniform. Comparing seismic velocity structures, there is no aftershock along the plate boundary where a large slip during the mainshock is estimated. Activity of aftershocks in the landward plate in the source region was high and normal fault-type, and strike-slip-type, mechanisms are dominant. Within the subducting oceanic plate, most earthquakes have also a normal fault-type, or strike-slip-type, mechanism. The stress fields in and around the source region change as a result of the mainshock.

  19. Distribution and migration of aftershocks of the 2010 Mw 7.4 Ogasawara Islands intraplate normal-faulting earthquake related to a fracture zone in the Pacific plate

    NASA Astrophysics Data System (ADS)

    Obana, Koichiro; Takahashi, Tsutomu; No, Tetsuo; Kaiho, Yuka; Kodaira, Shuichi; Yamashita, Mikiya; Sato, Takeshi; Nakamura, Takeshi

    2014-04-01

    describe the aftershocks of a Mw 7.4 intraplate normal-faulting earthquake that occurred 150 km east Ogasawara (Bonin) Islands, Japan, on 21 December 2010. It occurred beneath the outer trench slope of the Izu-Ogasawara trench, where the Pacific plate subducts beneath the Philippine Sea plate. Aftershock observations using ocean bottom seismographs (OBSs) began soon after the earthquake and multichannel seismic reflection surveys were conducted across the aftershock area. Aftershocks were distributed in a NW-SE belt 140 km long, oblique to the N-S trench axis. They formed three subparallel lineations along a fracture zone in the Pacific plate. The OBS observations combined with data from stations on Chichi-jima and Haha-jima Islands revealed a migration of the aftershock activity. The first hour, which likely outlines the main shock rupture, was limited to an 80 km long area in the central part of the subsequent aftershock area. The first hour activity occurred mainly around, and appears to have been influenced by, nearby large seamounts and oceanic plateau, such as the Ogasawara Plateau and the Uyeda Ridge. Over the following days, the aftershocks expanded beyond or into these seamounts and plateau. The aftershock distribution and migration suggest that crustal heterogeneities related to a fracture zone and large seamounts and oceanic plateau in the incoming Pacific plate affected the rupture of the main shock. Such preexisting structures may influence intraplate normal-faulting earthquakes in other regions of plate flexure prior to subduction.

  20. Quit4baby: Results From a Pilot Test of a Mobile Smoking Cessation Program for Pregnant Women

    PubMed Central

    2015-01-01

    Background Text messaging (short message service, SMS) programs have been shown to be effective in helping adult smokers quit smoking. This study describes the results of a pilot test of Quit4baby, a smoking cessation text messaging program for pregnant smokers that was adapted from Text2quit. Objective The study aimed to demonstrate the feasibility and acceptability of Quit4baby for women currently enrolled in Text4baby, a perinatal health text messaging program. Methods Pregnant women enrolled in Text4baby and who were current smokers or had quit within the last 4 weeks (n=20) were enrolled in Quit4baby. Those under the age of 18, not pregnant, not current smokers, those using nicotine replacement therapy, and those not interested in participating were ineligible. Participants were surveyed at baseline and at 2 and 4 weeks postenrollment. Results Most participants responded to the program favorably. Highly rated aspects included the content of the program, skills taught within the program, and encouragement and social support provided by the program. Participants reported that the program was helpful in quitting, that the program gave good ideas on quitting, and that they would recommend the program to a friend. Suggestions for improvement included increasing the message dose and making the quitpal more interactive. Conclusions This pilot test provides support for the feasibility and acceptability of Quit4baby. Future studies are needed to assess whether Quit4baby is effective for smoking cessation during pregnancy. PMID:25650765

  1. Earthquake source parameters for the 2010 January Haiti main shock and aftershock sequence

    NASA Astrophysics Data System (ADS)

    Nettles, Meredith; Hjörleifsdóttir, Vala

    2010-10-01

    Previous analyses of geological and geodetic data suggest that the obliquely compressive relative motion across the Caribbean-North America plate boundary in Hispaniola is accommodated through strain partitioning between near-vertical transcurrent faults on land and low-angle thrust faults offshore. In the Dominican Republic, earthquake focal-mechanism geometries generally support this interpretation. Little information has been available about patterns of seismic strain release in Haiti, however, due to the small numbers of moderate-to-large earthquakes occurring in western Hispaniola during the modern instrumental era. Here, we analyse the damaging MW = 7.0 earthquake that occurred near Port au Prince on 2010 January 12 and aftershocks occurring in the four months following this event, to obtain centroid-moment-tensor (CMT) solutions for 50 earthquakes with magnitudes as small as MW = 4.0. While the 2010 January main shock exhibited primarily strike-slip motion on a steeply dipping nodal plane (strike=250°, dip=71° and rake=22°), we find that nearly all of the aftershocks show reverse-faulting motion, typically on high-angle (30°-45°) nodal planes. Two small aftershocks (MW 4.5 and 4.6), located very close to the main shock epicentre, show strike-slip faulting with geometries similar to the main shock. One aftershock located off the south coast of Haiti shows low-angle thrust faulting. We also examine earthquakes occurring in this region from 1977-2009 successful analysis of four such events provides evidence for both strike-slip and reverse faulting. The pattern of seismic strain release in southern Haiti thus indicates that partitioning of plate motion between transcurrent and reverse structures extends far west within Hispaniola. While we see limited evidence for low-angle underthrusting offshore, most reverse motion appears to occur on high-angle fault structures adjacent to the Enriquillo fault. Our results highlight the need to incorporate seismogenic

  2. Source and Aftershock Analysis of a Large Deep Earthquake in the Tonga Flat Slab

    NASA Astrophysics Data System (ADS)

    Cai, C.; Wiens, D. A.; Warren, L. M.

    2013-12-01

    The 9 November 2009 (Mw 7.3) deep focus earthquake (depth = 591 km) occurred in the Tonga flat slab region, which is characterized by limited seismicity but has been imaged as a flat slab in tomographic imaging studies. In addition, this earthquake occurred immediately beneath the largest of the Fiji Islands and was well recorded by a temporary array of 16 broadband seismographs installed in Fiji and Tonga, providing an excellent opportunity to study the source mechanism of a deep earthquake in a partially aseismic flat slab region. We determine the positions of main shock hypocenter, its aftershocks and moment release subevents relative to the background seismicity using a hypocentroidal decomposition relative relocation method. We also investigate the rupture directivity by measuring the variation of rupture durations at different azimuth [e.g., Warren and Silver, 2006]. Arrival times picked from the local seismic stations together with teleseismic arrival times from the International Seismological Centre (ISC) are used for the relocation. Teleseismic waveforms are used for directivity study. Preliminary results show this entire region is relatively aseismic, with diffuse background seismicity distributed between 550-670 km. The main shock happened in a previously aseismic region, with only 1 small earthquake within 50 km during 1980-2012. 11 aftershocks large enough for good locations all occurred within the first 24 hours following the earthquake. The aftershock zone extends about 80 km from NW to SE, covering a much larger area than the mainshock rupture. The aftershock distribution does not correspond to the main shock fault plane, unlike the 1994 March 9 (Mw 7.6) Fiji-Tonga earthquake in the steeply dipping, highly seismic part of the Tonga slab. Mainshock subevent locations suggest a sub-horizontal SE-NW rupture direction. However, the directivity study shows a complicated rupture process which could not be solved with simple rupture assumption. We will

  3. Using the USGS Seismic Risk Web Application to estimate aftershock damage

    USGS Publications Warehouse

    McGowan, Sean M.; Luco, Nicolas

    2014-01-01

    The U.S. Geological Survey (USGS) Engineering Risk Assessment Project has developed the Seismic Risk Web Application to combine earthquake hazard and structural fragility information in order to calculate the risk of earthquake damage to structures. Enabling users to incorporate their own hazard and fragility information into the calculations will make it possible to quantify (in near real-time) the risk of additional damage to structures caused by aftershocks following significant earthquakes. Results can quickly be shared with stakeholders to illustrate the impact of elevated ground motion hazard and earthquake-compromised structural integrity on the risk of damage during a short-term, post-earthquake time horizon.

  4. Geotechnical effects of the 2015 magnitude 7.8 Gorkha, Nepal, earthquake and aftershocks

    USGS Publications Warehouse

    Moss, Robb E S; Thompson, Eric; Kieffer, D Scott; Tiwari, Binod; Hashash, Youssef M A; Acharya, Indra; Adhikari, Basanta; Asimaki, Domniki; Clahan, Kevin B.; Collins, Brian D.; Dahal, Sachindra; Jibson, Randall W.; Khadka, Diwakar; Macdonald, Amy; Madugo, Chris L M; Mason, H Benjamin; Pehlivan, Menzer; Rayamajhi, Deepak; Uprety, Sital

    2015-01-01

    This article summarizes the geotechnical effects of the 25 April 2015 M 7.8 Gorkha, Nepal, earthquake and aftershocks, as documented by a reconnaissance team that undertook a broad engineering and scientific assessment of the damage and collected perishable data for future analysis. Brief descriptions are provided of ground shaking, surface fault rupture, landsliding, soil failure, and infrastructure performance. The goal of this reconnaissance effort, led by Geotechnical Extreme Events Reconnaissance, is to learn from earthquakes and mitigate hazards in future earthquakes.

  5. Variation of b and p values from aftershocks sequences along the Mexican subduction zone and their relation to plate characteristics

    NASA Astrophysics Data System (ADS)

    Ávila-Barrientos, L.; Zúñiga, F. R.; Rodríguez-Pérez, Q.; Guzmán-Speziale, M.

    2015-11-01

    Aftershock sequences along the Mexican subduction margin (between coordinates 110ºW and 91ºW) were analyzed by means of the p value from the Omori-Utsu relation and the b value from the Gutenberg-Richter relation. We focused on recent medium to large (Mw > 5.6) events considered susceptible of generating aftershock sequences suitable for analysis. The main goal was to try to find a possible correlation between aftershock parameters and plate characteristics, such as displacement rate, age and segmentation. The subduction regime of Mexico is one of the most active regions of the world with a high frequency of occurrence of medium to large events and plate characteristics change along the subduction margin. Previous studies have observed differences in seismic source characteristics at the subduction regime, which may indicate a difference in rheology and possible segmentation. The results of the analysis of the aftershock sequences indicate a slight tendency for p values to decrease from west to east with increasing of plate age although a statistical significance is undermined by the small number of aftershocks in the sequences, a particular feature distinctive of the region as compared to other world subduction regimes. The b values show an opposite, increasing trend towards the east even though the statistical significance is not enough to warrant the validation of such a trend. A linear regression between both parameters provides additional support for the inverse relation. Moreover, we calculated the seismic coupling coefficient, showing a direct relation with the p and b values. While we cannot undoubtedly confirm the hypothesis that aftershock generation depends on certain tectonic characteristics (age, thickness, temperature), our results do not reject it thus encouraging further study into this question.

  6. Simultaneous estimation of b-values and detection rates of earthquakes for the application to aftershock probability forecasting

    NASA Astrophysics Data System (ADS)

    Katsura, K.; Ogata, Y.

    2004-12-01

    Reasenberg and Jones [Science, 1989, 1994] proposed the aftershock probability forecasting based on the joint distribution [Utsu, J. Fac. Sci. Hokkaido Univ., 1970] of the modified Omori formula of aftershock decay and Gutenberg-Richter law of magnitude frequency, where the respective parameters are estimated by the maximum likelihood method [Ogata, J. Phys. Earth, 1983; Utsu, Geophys Bull. Hokkaido Univ., 1965, Aki, Bull. Earthq. Res. Inst., 1965]. The public forecast has been implemented by the responsible agencies in California and Japan. However, a considerable difficulty in the above procedure is that, due to the contamination of arriving seismic waves, detection rate of aftershocks is extremely low during a period immediately after the main shock, say, during the first day, when the forecasting is most critical for public in the affected area. Therefore, for the forecasting of a probability during such a period, they adopt a generic model with a set of the standard parameter values in California or Japan. For an effective and realistic estimation, I propose to utilize the statistical model introduced by Ogata and Katsura [Geophys. J. Int., 1993] for the simultaneous estimation of the b-values of Gutenberg-Richter law together with detection-rate (probability) of earthquakes of each magnitude-band from the provided data of all detected events, where the both parameters are allowed for changing in time. Thus, by using all detected aftershocks from the beginning of the period, we can estimate the underlying modified Omori rate of both detected and undetected events and their b-value changes, taking the time-varying missing rates of events into account. The similar computation is applied to the ETAS model for complex aftershock activity or regional seismicity where substantial missing events are expected immediately after a large aftershock or another strong earthquake in the vicinity. Demonstrations of the present procedure will be shown for the recent examples

  7. Stress evolution following the 1999 Chi-Chi, Taiwan, earthquake: Consequences for afterslip, relaxation, aftershocks and departures from Omori decay

    USGS Publications Warehouse

    Chan, C.-H.; Stein, R.S.

    2009-01-01

    We explore how Coulomb stress transfer and viscoelastic relaxation control afterslip and aftershocks in a continental thrust fault system. The 1999 September 21 Mw = 7.6 Chi-Chi shock is typical of continental ramp-d??collement systems throughout the world, and so inferences drawn from this uniquely well-recorded event may be widely applicable. First, we find that the spatial and depth distribution of aftershocks and their focal mechanisms are consistent with the calculated Coulomb stress changes imparted by the coseismic rupture. Some 61 per cent of the M ??? 2 aftershocks and 83 per cent of the M ??? 4 aftershocks lie in regions for which the Coulomb stress increased by ???0.1 bars, and there is a 11-12 per cent gain in the percentage of aftershocks nodal planes on which the shear stress increased over the pre-Chi Chi control period. Second, we find that afterslip occurred where the calculated coseismic stress increased on the fault ramp and d??collement, subject to the condition that friction is high on the ramp and low on the d??collement. Third, viscoelastic relaxation is evident from the fit of the post-seismic GPS data on the footwall. Fourth, we find that the rate of seismicity began to increase during the post-seismic period in an annulus extending east of the main rupture. The spatial extent of the seismicity annulus resembles the calculated ???0.05-bar Coulomb stress increase caused by viscoelastic relaxation and afterslip, and we find a 9-12 per cent gain in the percentage of focal mechanisms with >0.01-bar shear stress increases imparted by the post-seismic afterslip and relaxation in comparison to the control period. Thus, we argue that post-seismic stress changes can for the first time be shown to alter the production of aftershocks, as judged by their rate, spatial distribution, and focal mechanisms. ?? Journal compilation ?? 2009 RAS.

  8. Stress loading from viscous flow in the lower crust and triggering of aftershocks following the 1994 Northridge, California, earthquake

    USGS Publications Warehouse

    Deng, J.; Hudnut, K.; Gurnis, M.; Hauksson, E.

    1999-01-01

    Following the M(w) 6.7 Northridge earthquake, significant postseismic displacements were resolved with GPS. Using a three-dimensional viscoelastic model, we suggest that this deformation is mainly driven by viscous flow in the lower crust. Such flow can transfer stress to the upper crust and load the rupture zone of the main shock at a decaying rate. Most aftershocks within the rupture zone, especially those that occurred after the first several weeks of the main shock, may have been triggered by continuous stress loading from viscous flow. The long-term decay time of aftershocks (about 2 years) approximately matches the decay of viscoelastic loading, and thus is controlled by the viscosity of the lower crust. Our model provides a physical interpretation of the observed correlation between aftershock decay rate and surface heat flow.Following the Mw 6.7 Northridge earthquake, significant postseismic displacements were resolved with GPS. Using a three-dimensional viscoelastic model, we suggest that this deformation is mainly driven by viscous flow in the lower crust. Such flow can transfer stress to the upper crust and load the rupture zone of the main shock at a decaying rate. Most aftershocks within the rupture zone, especially those that occurred after the first several weeks of the main shock, may have been triggered by continuous stress loading from viscous flow. The long-term decay time of aftershocks (about 2 years) approximately matches the decay of viscoelastic loading, and thus is controlled by the viscosity of the lower crust. Our model provides a physical interpretation of the observed correlation between aftershock decay rate and surface heat flow.

  9. Triggering of tsunamigenic aftershocks from large strike-slip earthquakes: Analysis of the November 2000 New Ireland earthquake sequence

    NASA Astrophysics Data System (ADS)

    Geist, Eric L.; Parsons, Tom

    2005-10-01

    The November 2000 New Ireland earthquake sequence started with a Mw = 8.0 left-lateral main shock on 16 November and was followed by a series of aftershocks with primarily thrust mechanisms. The earthquake sequence was associated with a locally damaging tsunami on the islands of New Ireland and nearby New Britain, Bougainville, and Buka. Results from numerical tsunami-propagation models of the main shock and two of the largest thrust aftershocks (Mw > 7.0) indicate that the largest tsunami was caused by an aftershock located near the southeastern termination of the main shock, off the southern tip of New Ireland (Aftershock 1). Numerical modeling and tide gauge records at regional and far-field distances indicate that the main shock also generated tsunami waves. Large horizontal displacements associated with the main shock in regions of steep bathymetry accentuated tsunami generation for this event. Most of the damage on Bougainville and Buka Islands was caused by focusing and amplification of tsunami energy from a ridge wave between the source region and these islands. Modeling of changes in the Coulomb failure stress field caused by the main shock indicate that Aftershock 1 was likely triggered by static stress changes, provided the fault was on or synthetic to the New Britain interplate thrust as specified by the Harvard CMT mechanism. For other possible focal mechanisms of Aftershock 1 and the regional occurrence of thrust aftershocks in general, evidence for static stress change triggering is not as clear. Other triggering mechanisms such as changes in dynamic stress may also have been important. The 2000 New Ireland earthquake sequence provides evidence that tsunamis caused by thrust aftershocks can be triggered by large strike-slip earthquakes. Similar tectonic regimes that include offshore accommodation structures near large strike-slip faults are found in southern California, the Sea of Marmara, Turkey, along the Queen Charlotte fault in British Columbia

  10. Educational Equality or Social Mobility: The Value Conflict between Preservice Teachers and the Free Teacher Education Program in China

    ERIC Educational Resources Information Center

    Wang, Dan; Gao, Manman

    2013-01-01

    In 2007, the Chinese government piloted the Free Teacher Education (FTE) program in the top normal universities with the aim to enlist high-quality young graduates to join the teaching profession and to improve education in underdeveloped rural regions. However, a conflict has arisen as FTE students enrolled in the program are reluctant to work in…

  11. Adapting a Database of Text Messages to a Mobile-Based Weight Loss Program: The Case of the Middle East

    PubMed Central

    Behih, Nawal; Shahzad, Maahd; Anggraini, Aysha

    2014-01-01

    Obesity has become a worldwide epidemic. Qatar, a rapidly developing country in the Middle East, has seen a sharp increase in the prevalence of obesity. The increase can be attributed to several reasons, including sedentary lifestyles imposed by a harsh climate and the introduction of Western fast food. Mobile technologies have been used and studied as a technology to support individuals' weight loss. The authors have developed a mobile application that implements three strategies drawn from proven theories of behavioral change. The application is localized to the cultural context of its proposed users. The objective of this paper is to present a method through which we adapted the messaging content of a weight loss application to the context of its users while retaining an effective degree of automation. The adaptation addressed body image, eating and physical exercise habits, and regional/cultural needs. The paper discusses how surveying potential users can be used to build a profile of a target population, find common patterns, and then develop a database of text messages. The text messages are automated and sent to the users at specific times of day, as suggested by the survey results. PMID:24511311

  12. The variability of PSV response spectra across a dense array deployed during the Northridge aftershock sequence

    USGS Publications Warehouse

    Field, E.H.; Hough, S.E.

    1997-01-01

    This study addresses the variability of pseudo-velocity response spectra across an array deployed on stiff soil in the San Fernando Valley during the Northridge (Mw 6.7) aftershock sequence. The separation between stations ranged from 0.5 to 5 km, and the aftershock magnitudes ranged from 2.3 to 4.0. We find that 95-percent of observed response spectra are within a factor of 1.9 to 2.6 of the network average. Statistically significant relative amplification factors were found for some of the sites, but the variability of observed response spectra is not significantly reduced by correcting for these effects. This implies that microzonation efforts on less than 5-km distance scales are not warranted at these types of sites. We also found a distance dependence for the response-spectral variability between neighboring sites. 95-percent are within a factor of ???2.3 at 0.5 km, increasing to 95-percent within a factor of ???4.2 at 5 km. No frequency dependence in these values could be resolved. Additional work is needed to examine the influence of other factors such as earthquake magnitude.

  13. Signature of Fault Healing in an Aftershock Sequence? The 2008 Wenchuan Earthquake

    NASA Astrophysics Data System (ADS)

    Zhang, Shengfeng; Wu, Zhongliang; Jiang, Changsheng

    2016-01-01

    We analyzed the aftershock sequence of the 2008 Wenchuan earthquake from May 12, 2008 to May 12, 2013 using the earthquake catalog of the China Earthquake Networks Center (CENC). In the analysis performed, we took under consideration the temporary variation in the completeness of the earthquake catalog just after the Wenchuan mainshock. The cutoff completeness magnitude from May 12 to June 27, 2008 was above 3.0 due to the impact of the earthquake sequence on the seismological observatory practice. It was observed that the b value has an increasing trend from June 27, 2008 to late April 2009, while since May 2009, the b value has remained stable. If these characteristics were associated with the possible signature of fault healing, the `apparent healing time' could be pinpointed by this measure as around 1 year. Due to two strong asperities present on the rupture of the Wenchuan mainshock, the aftershock zone can be divided into two segments, namely the north and the south segment. The b values of the two segments seem to show different trends of temporal variation. The main contribution of the increasing trend comes from the south segment, or the `initiation segment' of the main rupture.

  14. Including foreshocks and aftershocks in time-independent probabilistic seismic hazard analyses

    USGS Publications Warehouse

    Boyd, Oliver S.

    2012-01-01

    Time‐independent probabilistic seismic‐hazard analysis treats each source as being temporally and spatially independent; hence foreshocks and aftershocks, which are both spatially and temporally dependent on the mainshock, are removed from earthquake catalogs. Yet, intuitively, these earthquakes should be considered part of the seismic hazard, capable of producing damaging ground motions. In this study, I consider the mainshock and its dependents as a time‐independent cluster, each cluster being temporally and spatially independent from any other. The cluster has a recurrence time of the mainshock; and, by considering the earthquakes in the cluster as a union of events, dependent events have an opportunity to contribute to seismic ground motions and hazard. Based on the methods of the U.S. Geological Survey for a high‐hazard site, the inclusion of dependent events causes ground motions that are exceeded at probability levels of engineering interest to increase by about 10% but could be as high as 20% if variations in aftershock productivity can be accounted for reliably.

  15. Mobile screening mammography for the corporate customer.

    PubMed

    Kettlehake, J; Malott, J C

    1988-01-01

    While the concept of mobile imaging services is not new, mobile screening mammography has recently gained a great deal of attention, and several mobile breast screening programs are in operation throughout the United States. This article describes the development of a mobile breast screening program designed to attract corporations' employees as its primary source of participants. The design of the program, corporate concerns and operational issues are discussed as well as the findings of its first year of operation.

  16. Implementing a National Tractor Safety Program: Using "Whole System in a Room" to Mobilize Partners and Implement Solutions.

    PubMed

    Tinc, Pamela J; Ayers, Paul; May, John J; Purschwitz, Mark A; Park, Samantha; Bayes, Barbara; Sorensen, Julie

    2016-01-01

    Fatalities due to tractor overturns have long plagued the U.S. farm community. Constituting 20% of agricultural fatalities, tractor overturns contribute significantly to high rates of fatal injuries. In the past, many efforts have been directed toward reducing tractor overturns, with one successful US-based program offering rebates to farmers who retrofit their tractors with rollover protective structures (ROPS). In an effort to expand the program, the National Tractor Safety Coalition was formed. This coalition hosted a "Whole System in the Room" workshop to bring 50 stakeholders together. During this workshop, participants worked together to identify a common vision for the future of tractor safety and ROPS programs and commit to action. At the close of the workshop, coalition members set out to begin work on 100 short- and long-term commitments to begin implementing a National ROPS Rebate Program. PMID:26788905

  17. Gone Mobile? (Mobile Libraries Survey 2010)

    ERIC Educational Resources Information Center

    Thomas, Lisa Carlucci

    2010-01-01

    Librarians, like patrons and researchers, are caught between traditional library service models and the promise of evolving information technologies. In recent years, professional conferences have strategically featured programs and presentations geared toward building a mobile agenda and adapting or adopting services to meet new demands of mobile…

  18. Determination of the Fault Plane of the 2013 Santa Cruz Earthquake, Bolivia, Through Relative Location of Aftershocks

    NASA Astrophysics Data System (ADS)

    Rivadeneyra Vera, J. C.; Assumpcao, M.

    2015-12-01

    The Central Andes of southern Bolivia is a highly seismic region due to the faults present in this area which eventually could generate earthquakes up to 8.5 Mw. Nevertheless most of them are shallow and have low magnitude. In 2013, an earthquake of 5.0 Mw ocurred in Santa Cruz de la Sierra, it was followed by five aftershocks in the two months after the mainshock. Distances between epicenters of the aftershocks and the mainshock are up to 34 km, which is greater than expected for an earthquake of this magnitude. Additionaly the uncertainty of the epicenters is around 20 km; this scenario is not suitable for studies looking to determine the seismogenic fault orientation. Using data from South American stations of the international network of the Incorporated Research Institutions dor Seismology (IRIS) and the relative location technique, that uses the surface waves (usually the clearest wave in noisy sismograms), the epicenters of five aftershocks of the Santa Cruz series were determinated in relation the mainshock. This method enabled to achieve epicentral locations with uncertainties smaller than 2 km, distances between the aftershocks and the mainshock are up to 7 km, in accordance with the magnitude of the earthquake. The result of the relative location showed a N - S trend of the epicenters in agreement with the location and orientation of the Mandeyapecua fault, the largest reverse fault in Bolivia. Key words: Relative location, Surface waves

  19. Long aftershock sequences in North China and Central US: implications for hazard assessment in mid-continents

    NASA Astrophysics Data System (ADS)

    Liu, Mian; Luo, Gang; Wang, Hui; Stein, Seth

    2014-02-01

    Because seismic activity within mid-continents is usually much lower than that along plate boundary zones, even small earthquakes can cause widespread concerns, especially when these events occur in the source regions of previous large earthquakes. However, these small earthquakes may be just aftershocks that continue for decades or even longer. The recent seismicity in the Tangshan region in North China is likely aftershocks of the 1976 Great Tangshan earthquake. The current earthquake sequence in the New Madrid seismic zone in central United States, which includes a cluster of M ~ 7.0 events in 1811-1812 and a number of similar events in the past millennium, is believed to result from recent fault reactivation that releases pre-stored strain energy in the crust. If so, this earthquake sequence is similar to aftershocks in that the rates of energy release should decay with time and the sequence of earthquakes will eventually end. We use simple physical analysis and numerical simulations to show that the current sequence of large earthquakes in the New Madrid fault zone is likely ending or has ended. Recognizing that mid-continental earthquakes have long aftershock sequences and complex spatiotemporal occurrences are critical to improve hazard assessments.

  20. Aftershocks are well aligned with the background stress field, contradicting the hypothesis of highly-heterogeneous crustal stress

    USGS Publications Warehouse

    Hardebeck, Jeanne L.

    2010-01-01

    It has been proposed that the crustal stress field contains small-length-scale heterogeneity of much larger amplitude than the uniform background stress. This model predicts that earthquake focal mechanisms should reflect the loading stress rather than the uniform background stress. So, if the heterogeneous stress hypothesis is correct, focal mechanisms before and after a large earthquake should align with the tectonic loading and the earthquake-induced static stress perturbation, respectively. However, I show that the off-fault triggered aftershocks of the 1992 M7.3 Landers, California, earthquake align with the same stress field as the pre-Landers mechanisms. The aftershocks occurred on faults that were well oriented for failure in the pre-Landers stress field and then loaded by the Landers-induced static stress change. Aftershocks in regions experiencing a 0.05 to 5 MPa coseismic differential stress change align with the modeled Landers-induced static stress change, implying that they were triggered by the stress perturbation. Contrary to the heterogeneous stress hypothesis, these triggered aftershocks are also well aligned with the pre-Landers stress field obtained from inverting the pre-Landers focal mechanisms. Therefore, the inverted pre-Landers stress must represent the persistent background stress field. Earthquake focal mechanisms provide an unbiased sample of the spatially coherent background stress field, which is large relative to any small-scale stress heterogeneity. The counterexample provided by the Landers earthquake is strong evidence that the heterogeneous stress model is not widely applicable.

  1. Kinematic rupture process of the 2007 Tocopilla earthquake and its main aftershocks from teleseismic and strong-motion data

    NASA Astrophysics Data System (ADS)

    Peyrat, S.; Madariaga, R.; Buforn, E.; Campos, J.; Asch, G.; Vilotte, J. P.

    2010-09-01

    We study a large Mw = 7.6 earthquake that occurred on 2007 November 14 in the Northern Chile seismic gap near the city of Tocopilla. Using a variety of seismic data we show that this earthquake ruptured only the lower part of the interplate seismic zone and generated a series of plate interface aftershocks. Two large aftershocks on 2007 November 15 ruptured the interplate zone oceanwards of the Mejillones Peninsula, a major geographical feature in the Antofagasta region. On 2007 December 16, a large Mw = 6.8 aftershock, that occurred near the southern bottom of the fault plane of the main event, is shown to be a slab-push earthquake located inside the subducted Nazca Plate and triggered by along slab compression. Aftershocks of this event demonstrate that it occurred on an almost vertical fault. The Tocopilla earthquake took place just after the installation of a new seismological network by Chilean, German and French researchers. The accelerometric data combined with far field seismic data provide a quite complete and consistent view of the rupture process. The earthquake broke a long (130 km) and narrow (about 30-50 km) zone of the plate interface just above the transition zone. Using a non-linear kinematic inversion method, we determined that rupture occurred on two well-defined patches of roughly elliptical shape. We discuss the consequences of this event for models of gap filling earthquakes in Chile proposed in the 1970s.

  2. GIS-based 3D modeling and visualization of the Mw7.7, 2007, Tocopilla aftershocks

    NASA Astrophysics Data System (ADS)

    Eggert, S.; Sobiesiak, M.

    2009-04-01

    The November 14, 2007 Mw 7.7 earthquake nucleated on the west coast of northern Chile about 40 km east of the city of Tocopilla. It took place in the southern part of the of a large seismic gap namely, the Iquique subduction zone segment which is supposed to be at the end of its seismic cycle. The Tocopilla fault plane appears to be the northern continuation of the Mw 8.0, 1995 Antofagasta earthquake. We present a complex 3D model of the rupture area including first hypocenter localizations of aftershocks following the event. The data was recorded during a mission of the German Task Force for Earthquakes after the 2007 Tocopilla earthquake. 34 seismic stations were recording the aftershocks from November 2007 until May 2008. In general, subduction zones have a complex structure where most of the volumes examined are characterized by strong variations in physical and material parameters and are far away from a homogeneously layered half space. Therefore, 3D representation of the geophysical and geological conditions to be found are of great importance to understand such a subduction environment. Using ArcScene as a three-dimensional modeling tool gives us the possibility to visualize the aftershock distribution along the subducting slab and identify clear structures and clusters within the data set. Furthermore we combine the 2007 Tocopilla data set with the 1995 Antofagasta aftershocks which provides a new, three-dimensional insight into the segment boundary of these two events.

  3. Aftershock distribution as a constraint on the geodetic model of coseismic slip for the 2004 Parkfield earthquake

    USGS Publications Warehouse

    Bennington, Ninfa; Thurber, Clifford; Feigl, Kurt; ,

    2011-01-01

    Several studies of the 2004 Parkfield earthquake have linked the spatial distribution of the event’s aftershocks to the mainshock slip distribution on the fault. Using geodetic data, we find a model of coseismic slip for the 2004 Parkfield earthquake with the constraint that the edges of coseismic slip patches align with aftershocks. The constraint is applied by encouraging the curvature of coseismic slip in each model cell to be equal to the negative of the curvature of seismicity density. The large patch of peak slip about 15 km northwest of the 2004 hypocenter found in the curvature-constrained model is in good agreement in location and amplitude with previous geodetic studies and the majority of strong motion studies. The curvature-constrained solution shows slip primarily between aftershock “streaks” with the continuation of moderate levels of slip to the southeast. These observations are in good agreement with strong motion studies, but inconsistent with the majority of published geodetic slip models. Southeast of the 2004 hypocenter, a patch of peak slip observed in strong motion studies is absent from our curvature-constrained model, but the available GPS data do not resolve slip in this region. We conclude that the geodetic slip model constrained by the aftershock distribution fits the geodetic data quite well and that inconsistencies between models derived from seismic and geodetic data can be attributed largely to resolution issues.

  4. A High School-Collegiate Outreach Program in Chemistry and Biology Delivering Modern Technology in a Mobile Van

    NASA Astrophysics Data System (ADS)

    Craney, Chris; Mazzeo, April; Lord, Kaye

    1996-07-01

    During the past five years the nation's concern for science education has expanded from a discussion about the future supply of Ph.D. scientists and its impact on the nation's scientific competitiveness to the broader consideration of the science education available to all students. Efforts to improve science education have led many authors to suggest greater collaboration between high school science teachers and their college/university colleagues. This article reviews the experience and outcomes of the Teachers + Occidental = Partnership in Science (TOPS) van program operating in the Los Angeles Metropolitan area. The program emphasizes an extensive ongoing staff development, responsiveness to teachers' concerns, technical and on-site support, and sustained interaction between participants and program staff. Access to modern technology, including computer-driven instruments and commercial data analysis software, coupled with increased teacher content knowledge has led to empowerment of teachers and changes in student interest in science. Results of student and teacher questionnaires are reviewed.

  5. A Guided Online and Mobile Self-Help Program for Individuals With Eating Disorders: An Iterative Engagement and Usability Study

    PubMed Central

    Dimopoulos, Christina N; Flaschberger, Edith; Saffran, Kristina; Kruger, Jenna F; Garlock, Lindsay; Wilfley, Denise E; Taylor, Craig B; Jones, Megan

    2016-01-01

    Background Numerous digital health interventions have been developed for mental health promotion and intervention, including eating disorders. Efficacy of many interventions has been evaluated, yet knowledge about reasons for dropout and poor adherence is scarce. Most digital health intervention studies lack appropriate research design and methods to investigate individual engagement issues. User engagement and program usability are inextricably linked, making usability studies vital in understanding and improving engagement. Objective The aim of this study was to explore engagement and corresponding usability issues of the Healthy Body Image Program—a guided online intervention for individuals with body image concerns or eating disorders. The secondary aim was to demonstrate the value of usability research in order to investigate engagement. Methods We conducted an iterative usability study based on a mixed-methods approach, combining cognitive and semistructured interviews as well as questionnaires, prior to program launch. Two separate rounds of usability studies were completed, testing a total of 9 potential users. Thematic analysis and descriptive statistics were used to analyze the think-aloud tasks, interviews, and questionnaires. Results Participants were satisfied with the overall usability of the program. The average usability score was 77.5/100 for the first test round and improved to 83.1/100 after applying modifications for the second iteration. The analysis of the qualitative data revealed five central themes: layout, navigation, content, support, and engagement conditions. The first three themes highlight usability aspects of the program, while the latter two highlight engagement issues. An easy-to-use format, clear wording, the nature of guidance, and opportunity for interactivity were important issues related to usability. The coach support, time investment, and severity of users’ symptoms, the program’s features and effectiveness, trust

  6. Foreshocks and aftershocks of Pisagua 2014 earthquake: time and space evolution of megathrust event.

    NASA Astrophysics Data System (ADS)

    Fuenzalida Velasco, Amaya; Rietbrock, Andreas; Wollam, Jack; Thomas, Reece; de Lima Neto, Oscar; Tavera, Hernando; Garth, Thomas; Ruiz, Sergio

    2016-04-01

    The 2014 Pisagua earthquake of magnitude 8.2 is the first case in Chile where a foreshock sequence was clearly recorded by a local network, as well all the complete sequence including the mainshock and its aftershocks. The seismicity of the last year before the mainshock include numerous clusters close to the epicentral zone (Ruiz et al; 2014) but it was on 16th March that this activity became stronger with the Mw 6.7 precursory event taking place in front of Iquique coast at 12 km depth. The Pisagua earthquake arrived on 1st April 2015 breaking almost 120 km N-S and two days after a 7.6 aftershock occurred in the south of the rupture, enlarging the zone affected by this sequence. In this work, we analyse the foreshocks and aftershock sequence of Pisagua earthquake, from the spatial and time evolution for a total of 15.764 events that were recorded from the 1st March to 31th May 2015. This event catalogue was obtained from the automatic analyse of seismic raw data of more than 50 stations installed in the north of Chile and the south of Peru. We used the STA/LTA algorithm for the detection of P and S arrival times on the vertical components and then a method of back propagation in a 1D velocity model for the event association and preliminary location of its hypocenters following the algorithm outlined by Rietbrock et al. (2012). These results were then improved by locating with NonLinLoc software using a regional velocity model. We selected the larger events to analyse its moment tensor solution by a full waveform inversion using ISOLA software. In order to understand the process of nucleation and propagation of the Pisagua earthquake, we also analysed the evolution in time of the seismicity of the three months of data. The zone where the precursory events took place was strongly activated two weeks before the mainshock and remained very active until the end of the analysed period with an important quantity of the seismicity located in the upper plate and having

  7. A Crustal Structure Study of the Southern Ryukyu Subduction Zone by Using the Aftershock Data

    NASA Astrophysics Data System (ADS)

    Cho, Y.; Lin, J.; Lee, C.

    2011-12-01

    The region along the Ryukyu subduction zone is known as a tsunami disaster zone. The biggest tsunami (85 m) of Japan history was recorded in the Ishigaki Island, Ryukyu, in 1771. The paleo-tsunami events show that it has a frequency of about 150 years. This thread makes the Ryukyu subduction zone as a concerned field for the earthquake studies. However, due to the long distance from the east coast of Taiwan, this is an area out of the effective earthquake detection zone from the Central Weather Bureau network. A main shock of M = 6.9 occurred near the Ishigaki Island in 2009 August 17. After this event, we quickly deployed the OBS and found many aftershocks with the magnitude greater than 5.0. The main shock was 240 km, NE direction from the Hualien city, Taiwan. If a tsunami occurred, it took only less than 15 minutes to arrive the coast. From the recorded data, we picked the P- and S-wave using the 1-D module (iasp91). There were 1500 recorded events during those time range, and most of the earthquakes were located around the Nanao Basin. Based on this, we study the southern Ryukyu subduction zone structure by using the results from focal mechanism solution. From the earthquake relocation it shows that two main groups of aftershocks. They tend in northwest - southeast with a left-lateral strike-slip fault. The left-lateral strike-slip fault is the main structures that link with the splay faults at the southern Ryukyu Trench. The stability and extension of the splay faults are one of the major concerns for the occurrence of mega earthquake. More than 500-km long of the splay fault, such as that in the Indonesia, Chile and Japan subduction zones, has attacked by mega earthquakes in the recent years. The second group of those aftershocks was located in the Gagua Ridge near the Ryukyu Trench. This group may represent the ridge structure relate to the Taitung canyon fault. The front of Ryukyu Trench was being as a locked subduction zone where it is easily to

  8. The Seismic Aftershock Monitoring System (SAMS) for OSI - Experiences from IFE14

    NASA Astrophysics Data System (ADS)

    Gestermann, Nicolai; Sick, Benjamin; Häge, Martin; Blake, Thomas; Labak, Peter; Joswig, Manfred

    2016-04-01

    An on-site inspection (OSI) is the third of four elements of the verification regime of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The sole purpose of an OSI is to confirm whether a nuclear weapon test explosion or any other nuclear explosion has been carried out in violation of the treaty and to gather any facts which might assist in identifying any possible violator. It thus constitutes the final verification measure under the CTBT if all other available measures are not able to confirm the nature of a suspicious event. The Provisional Technical Secretariat (PTS) carried out the Integrated Field Exercise 2014 (IFE14) in the Dead Sea Area of Jordan from 3 November to 9. December 2014. It was a fictitious OSI whose aim was to test the inspection capabilities in an integrated manner. The technologies allowed during an OSI are listed in the Treaty. The aim of the Seismic Aftershock Monitoring System (SAMS) is to detect and localize aftershocks of low magnitudes of the triggering event or collapses of underground cavities. The locations of these events are expected in the vicinity of a possible previous explosion and help to narrow down the search area within an inspection area (IA) of an OSI. The success of SAMS depends on the main elements, hardware, software, deployment strategy, the search logic and not least the effective use of personnel. All elements of SAMS were tested and improved during the Built-Up Exercises (BUE) which took place in Austria and Hungary. IFE14 provided more realistic climatic and hazardous terrain conditions with limited resources. Significant variations in topography of the IA of IFE14 in the mountainous Dead Sea Area of Jordan led to considerable challenges which were not expected from experiences encountered during BUE. The SAMS uses mini arrays with an aperture of about 100 meters and with a total of 4 elements. The station network deployed during IFE14 and results of the data analysis will be presented. Possible aftershocks of

  9. A Study of the Feasibility of a Health Occupations Career Mobility Program for Oklahoma. A Final Report.

    ERIC Educational Resources Information Center

    Ward, Sharon K.; And Others

    The purpose of the study was to develop a formal, organized, widely agreed upon and accepted program for assuring the most effective and efficient advancement of persons interested in expanding their competencies and responsibilities in health occupations. Information was collected via personal interviews, mail questionnaires, and telephone…

  10. From a Knowledge Container to a Mobile Learning Platform: What RULA Learned from the Laptop Lending Program

    ERIC Educational Resources Information Center

    Wang, Weina; Dermody, Kelly; Burgess, Colleen; Wang, Fangmin

    2014-01-01

    Technology lending has proven to be one of the most popular services that the Ryerson University Library and Archives (RULA) has offered in the past few years. Given the number of commuting digital natives comprising our student body, the library wanted to know how these students were using our current laptop loan program and how this service…

  11. International Student Mobility Programs and Effects on Student Teachers' Perceptions and Beliefs about Education and Their Role as Future Educators

    ERIC Educational Resources Information Center

    Richardson, Rachel; Munday, Jennifer

    2013-01-01

    The aim of this study was to examine the value and benefits obtained from a semester length academic exchange for Australian early childhood teacher education students in equivalent programs in selected European sites. The data obtained from interviews conducted in this qualitative study indicate that students involved in the international…

  12. The 25 March 1993 Scotts Mills, Oregon, earthquake and aftershock sequence: Spatial distribution, focal mechanisms, and the mount angel fault

    USGS Publications Warehouse

    Thomas, G.C.; Crosson, R.S.; Carver, D.L.; Yelin, T.S.

    1996-01-01

    The 25 March 1993 ML = 5.7 crustal earthquake near Scotts Mills, Oregon, was the largest earthquake to occur in the Pacific Northwest in over a decade. The mainshock was located at 45.033?? N, 122.586?? W and at a depth of about 15.1 km, based on arrival time data from the short-period Pacific Northwest Seismograph Network. Beginning about 12 h after the mainshock, investigators from the U.S. Geological Survey deployed 22 digital seismographs to record aftershocks. Using data from the temporary and permanent stations, we analyzed a subset of 50 after-shocks with quality locations. Hypocenters of these aftershocks lie on a northwesttrending steeply dipping plane (strike 290 ?? 10??, dipping 60 ?? 5?? to the north-northeast), in agreement with the preferred slip plane of the mainshock focal mechanism solution (strike 294??, dipping 58?? to the north-northeast). The planar structure defined by the aftershock locations may be a southeast continuation of the Mount Angel Fault, a reverse fault identified from both surface and subsurface evidence. The mapped southeast extent of the Mount Angel Fault is located less than 10 km west of the Scotts Mills epicentral region. In addition, the mainshock focal mechanism solution, with a combination of reverse motion and right-lateral strike slip, has a geometry and sense of motion consistent with the Mount Angel Fault. While aftershock focal mechanisms are varied, P axes are consistently oriented in a subhorizontal north-south direction. This earthquake sequence, together with the geological and geophysical evidence for the Mount Angel Fault, suggests a significant crustal earthquake hazard for this region of northwest Oregon.

  13. Teleseismic Body Wave Analysis for the 27 September 2003 Altai, Earthquake (Mw7.4) and Large Aftershocks

    NASA Astrophysics Data System (ADS)

    Gomez-Gonzalez, J. M.; Mellors, R.

    2007-05-01

    We investigate the kinematics of the rupture process for the September 27, 2003, Mw7.3, Altai earthquake and its associated large aftershocks. This is the largest earthquake striking the Altai mountains within the last 50 years, which provides important constraints on the ongoing tectonics. The fault plane solution obtained by teleseismic body waveform modeling indicated a predominantly strike-slip event (strike=130, dip=75, rake 170), Scalar moment for the main shock ranges from 0.688 to 1.196E+20 N m, a source duration of about 20 to 42 s, and an average centroid depth of 10 km. Source duration would indicate a fault length of about 130 - 270 km. The main shock was followed closely by two aftershocks (Mw5.7, Mw6.4) occurred the same day, another aftershock (Mw6.7) occurred on 1 October , 2003. We also modeled the second aftershock (Mw6.4) to asses geometric similarities during their respective rupture process. This aftershock occurred spatially very close to the mainshock and possesses a similar fault plane solution (strike=128, dip=71, rake=154), and centroid depth (13 km). Several local conditions, such as the crustal model and fault geometry, affect the correct estimation of some source parameters. We perfume a sensitivity evaluation of several parameters, including centroid depth, scalar moment and source duration, based on a point and finite source modeling. The point source approximation results are the departure parameters for the finite source exploration. We evaluate the different reported parameters to discard poor constrained models. In addition, deformation data acquired by InSAR are also included in the analysis.

  14. Mammography-based screening program: preliminary results from a first 2-year round in a Brazilian region using mobile and fixed units

    PubMed Central

    2012-01-01

    Background Breast cancer is the most frequently diagnosed cancer and the leading cause of cancer deaths among women worldwide. The use of mobile mammography units to offer screening to women living in remote areas is a rational strategy to increase the number of women examined. This study aimed to evaluate results from the first 2 years of a government-organized mammography screening program implemented with a mobile unit (MU) and a fixed unit (FU) in a rural county in Brazil. The program offered breast cancer screening to women living in Barretos and the surrounding area. Methods Based on epidemiologic data, 54 238 women, aged 40 to 69 years, were eligible for breast cancer screening. The study included women examined from April 1, 2003 to March 31, 2005. The chi-square test and Bonferroni correction analyses were used to evaluate the frequencies of tumors and the importance of clinical parameters and tumor characteristics. Significance was set at p < 0.05. Results Overall, 17 964 women underwent mammography. This represented 33.1% of eligible women in the area. A mean of 18.6 and 26.3 women per day were examined in the FU and MU, respectively. Seventy six patients were diagnosed with breast cancer (41 (54%) in the MU). This represented 4.2 cases of breast cancer per 1000 examinations. The number of cancers detected was significantly higher in women aged 60 to 69 years than in those aged 50 to 59 years (p < 0.001) or 40 to 49 years (p < 0.001). No difference was observed between women aged 40 to 49 years and those aged 50 to 59 years (p = 0.164). The proportion of tumors in the early (EC 0 and EC I) and advanced (CS III and CS IV) stages of development were 43.4% and 15.8%, respectively. Conclusions Preliminary results indicate that this mammography screening program is feasible for implementation in a rural Brazilian territory and favor program continuation. PMID:23031787

  15. Grand Junction projects office mixed-waste treatment program, VAC*TRAX mobile treatment unit process hazards analysis

    SciTech Connect

    Bloom, R.R.

    1996-04-01

    The objective of this report is to demonstrate that a thorough assessment of the risks associated with the operation of the Rust Geotech patented VAC*TRAX mobile treatment unit (MTU) has been performed and documented. The MTU was developed to treat mixed wastes at the US Department of Energy (DOE) Albuquerque Operations Office sites. The MTU uses an indirectly heated, batch vacuum dryer to thermally desorb organic compounds from mixed wastes. This process hazards analysis evaluated 102 potential hazards. The three significant hazards identified involved the inclusion of oxygen in a process that also included an ignition source and fuel. Changes to the design of the MTU were made concurrent with the hazard identification and analysis; all hazards with initial risk rankings of 1 or 2 were reduced to acceptable risk rankings of 3 or 4. The overall risk to any population group from operation of the MTU was determined to be very low; the MTU is classified as a Radiological Facility with low hazards.

  16. The Gorkha earthquake of April 25, 2015 in Nepal: Tectonic position, aftershock process, and possibilities of forecasting the evolution of seismic situation

    NASA Astrophysics Data System (ADS)

    Rogozhin, E. A.; Lutikov, A. I.; Sobisevich, L. E.; Shen, To; Kanonidi, K. Kh.

    2016-07-01

    The characteristics of the foci for the main shock and strongest aftershocks of the Gorkha earthquake of April 25, 2015 in Nepal are described. The macroseismic data and examples of seismic dislocations are discussed. The progression of the release of seismic energy by the aftershock process is analyzed. The data for the geophysical and seismological precursors of the main shock and the strongest aftershock of May 12, 2015 are presented. These data allowed us to formulate the short-term forecast of this event.

  17. Exploring the limits of waveform correlation event detection as applied to three earthquake aftershock sequences.

    SciTech Connect

    Resor, Megan E.; Carr, Dorthe Bame; Young, Christopher John

    2010-05-01

    Swarms of earthquakes and/or aftershock sequences can dramatically increase the level of seismicity in a region for a period of time lasting from days to months, depending on the swarm or sequence. Such occurrences can provide a large amount of useful information to seismologists. For those who monitor seismic events for possible nuclear explosions, however, these swarms/sequences are a nuisance. In an explosion monitoring system, each event must be treated as a possible nuclear test until it can be proven, to a high degree of confidence, not to be. Seismic events recorded by the same station with highly correlated waveforms almost certainly have a similar location and source type, so clusters of events within a swarm can quickly be identified as earthquakes. We have developed a number of tools that can be used to exploit the high degree of waveform similarity expected to be associated with swarms/sequences. Dendro Tool measures correlations between known events. The Waveform Correlation Detector is intended to act as a detector, finding events in raw data which correlate with known events. The Self Scanner is used to find all correlated segments within a raw data steam and does not require an event library. All three techniques together provide an opportunity to study the similarities of events in an aftershock sequence in different ways. To comprehensively characterize the benefits and limits of waveform correlation techniques, we studied 3 aftershock sequences, using our 3 tools, at multiple stations. We explored the effects of station distance and event magnitudes on correlation results. Lastly, we show the reduction in detection threshold and analyst workload offered by waveform correlation techniques compared to STA/LTA based detection. We analyzed 4 days of data from each aftershock sequence using all three methods. Most known events clustered in a similar manner across the toolsets. Up to 25% of catalogued events were found to be a member of a cluster. In

  18. Foreshocks and aftershocks of strong earthquakes in the light of catastrophe theory

    NASA Astrophysics Data System (ADS)

    Guglielmi, A. V.

    2015-04-01

    In this review, general ideas and specific results from catastrophe theory and the theory of critical phenomena are applied to the analysis of strong earthquakes. Aspects given particular attention are the sharp rise in the fluctuation level, the increased reactivity of dynamical systems in the near-threshold region, and other anomalous phenomena similar to critical opalescence. Given the lack of a sufficiently complete theory of earthquakes, this appears to be a valid approach to the analysis of observations. The study performed brought out some nontrivial properties of a strong-earthquake source that manifest themselves both before and after the main rupture discontinuity forms at the mainshock. In the course of the analysis of the foreshocks and aftershocks, such concepts as the round-the-world seismic echo, the cumulative effect of converging surface waves on the epicentral zone, and global seismicity modulation by Earth's free oscillations are introduced. Further research in this field is likely to be interesting and promising.

  19. The study of recent seismicity in the aftershock area of Neftegorsk earthquake using waveform cross correlation

    NASA Astrophysics Data System (ADS)

    Kitov, Ivan; Turuntaev, Sergey; Konovalov, Alexei; Stepnov, Andrey

    2016-04-01

    Unusually long duration of seismic activity (more than 20 years) was observed in the aftershock area of the 1995 Neftegorsk, Sakhalin, Russia catastrophic earthquake (Ms=7.6). To study the phenomena, we have processed seismic data from 130 events occurred within that area as measured between 2006 and 2015. In order to improve the accuracy of relative location and magnitude estimation of these events we have applied new techniques based on waveform cross correlation. We use 7 three-component (3-C) seismic stations which detected most of these events. Three-component waveform templates were prepared for these stations from those events which had signals with SNR>5 at vertical channels. The events with 3 and more templates are used as master-events for waveform cross correlation. Overall, the re-estimated location and magnitudes demonstrate higher precisions and are used for the statistical analysis and numerical modelling of seismo-tectonic regime within the studied zone.

  20. Applications of the predictability of the Coherent Noise Model to aftershock sequences

    NASA Astrophysics Data System (ADS)

    Christopoulos, Stavros-Richard; Sarlis, Nicholas

    2014-05-01

    A study [1] of the coherent noise model [2-4] in natural time [5-7] has shown that it exhibits predictability. Interestingly, one of the predictors suggested [1] for the coherent noise model can be generalized and applied to the case of (real) aftershock sequences. The results obtained [8] so far are beyond chance. Here, we apply this approach to several aftershock sequences of strong earthquakes with magnitudes Mw ≥6.9 in Indonesia, California and Greece, including the Mw9.2 earthquake that occurred on 26 December 2004 in Sumatra. References. [1] N. V. Sarlis and S.-R. G. Christopoulos, Predictability of the coherent-noise model and its applications, Physical Review E, 85, 051136, 2012. [2] M.E.J. Newman, Self-organized criticality, evolution and the fossil extinction record, Proc. R. Soc. London B, 263, 1605-1610, 1996. [3] M. E. J. Newman and K. Sneppen, Avalanches, scaling, and coherent noise, Phys. Rev. E, 54, 6226-6231, 1996. [4] K. Sneppen and M. Newman, Coherent noise, scale invariance and intermittency in large systems, Physica D, 110, 209 - 222. [5] P. Varotsos, N. Sarlis, and E. Skordas, Spatiotemporal complexity aspects on the interrelation between Seismic Electric Signals and seismicity, Practica of Athens Academy, 76, 294-321, 2001. [6] P.A. Varotsos, N.V. Sarlis, and E.S. Skordas, Long-range correlations in the electric signals that precede rupture, Phys. Rev. E, 66, 011902, 2002. [7] Varotsos P. A., Sarlis N. V. and Skordas E. S., Natural Time Analysis: The new view of time. Precursory Seismic Electric Signals, Earthquakes and other Complex Time-Series (Springer-Verlag, Berlin Heidelberg) 2011. [8] N. V. Sarlis and S.-R. G. Christopoulos, "Visualization of the significance of Receiver Operating Characteristics based on confidence ellipses", Computer Physics Communications, http://dx.doi.org/10.1016/j.cpc.2013.12.009

  1. The 11 April 2012 east Indian Ocean earthquake triggered large aftershocks worldwide.

    PubMed

    Pollitz, Fred F; Stein, Ross S; Sevilgen, Volkan; Bürgmann, Roland

    2012-10-11

    Large earthquakes trigger very small earthquakes globally during passage of the seismic waves and during the following several hours to days, but so far remote aftershocks of moment magnitude M ≥ 5.5 have not been identified, with the lone exception of an M = 6.9 quake remotely triggered by the surface waves from an M = 6.6 quake 4,800 kilometres away. The 2012 east Indian Ocean earthquake that had a moment magnitude of 8.6 is the largest strike-slip event ever recorded. Here we show that the rate of occurrence of remote M ≥ 5.5 earthquakes (>1,500 kilometres from the epicentre) increased nearly fivefold for six days after the 2012 event, and extended in magnitude to M ≤ 7. These global aftershocks were located along the four lobes of Love-wave radiation; all struck where the dynamic shear strain is calculated to exceed 10(-7) for at least 100 seconds during dynamic-wave passage. The other M ≥ 8.5 mainshocks during the past decade are thrusts; after these events, the global rate of occurrence of remote M ≥ 5.5 events increased by about one-third the rate following the 2012 shock and lasted for only two days, a weaker but possibly real increase. We suggest that the unprecedented delayed triggering power of the 2012 earthquake may have arisen because of its strike-slip source geometry or because the event struck at a time of an unusually low global earthquake rate, perhaps increasing the number of nucleation sites that were very close to failure.

  2. The 11 April 2012 east Indian Ocean earthquake triggered large aftershocks worldwide.

    PubMed

    Pollitz, Fred F; Stein, Ross S; Sevilgen, Volkan; Bürgmann, Roland

    2012-10-11

    Large earthquakes trigger very small earthquakes globally during passage of the seismic waves and during the following several hours to days, but so far remote aftershocks of moment magnitude M ≥ 5.5 have not been identified, with the lone exception of an M = 6.9 quake remotely triggered by the surface waves from an M = 6.6 quake 4,800 kilometres away. The 2012 east Indian Ocean earthquake that had a moment magnitude of 8.6 is the largest strike-slip event ever recorded. Here we show that the rate of occurrence of remote M ≥ 5.5 earthquakes (>1,500 kilometres from the epicentre) increased nearly fivefold for six days after the 2012 event, and extended in magnitude to M ≤ 7. These global aftershocks were located along the four lobes of Love-wave radiation; all struck where the dynamic shear strain is calculated to exceed 10(-7) for at least 100 seconds during dynamic-wave passage. The other M ≥ 8.5 mainshocks during the past decade are thrusts; after these events, the global rate of occurrence of remote M ≥ 5.5 events increased by about one-third the rate following the 2012 shock and lasted for only two days, a weaker but possibly real increase. We suggest that the unprecedented delayed triggering power of the 2012 earthquake may have arisen because of its strike-slip source geometry or because the event struck at a time of an unusually low global earthquake rate, perhaps increasing the number of nucleation sites that were very close to failure. PMID:23023131

  3. Constraints on recent earthquake source parameters, fault geometry and aftershock characteristics in Oklahoma

    NASA Astrophysics Data System (ADS)

    McNamara, D. E.; Benz, H.; Herrmann, R. B.; Bergman, E. A.; McMahon, N. D.; Aster, R. C.

    2014-12-01

    In late 2009, the seismicity of Oklahoma increased dramatically. The largest of these earthquakes was a series of three damaging events (Mw 4.8, 5.6, 4.8) that occurred over a span of four days in November 2011 near the town of Prague in central Oklahoma. Studies suggest that these earthquakes were induced by reactivation of the Wilzetta fault due to the disposal of waste water from hydraulic fracturing ("fracking") and other oil and gas activities. The Wilzetta fault is a northeast trending vertical strike-slip fault that is a well known structural trap for oil and gas. Since the November 2011 Prague sequence, thousands of small to moderate (M2-M4) earthquakes have occurred throughout central Oklahoma. The most active regions are located near the towns of Stillwater and Medford in north-central Oklahoma, and Guthrie, Langston and Jones near Oklahoma City. The USGS, in collaboration with the Oklahoma Geological Survey and the University of Oklahoma, has responded by deploying numerous temporary seismic stations in the region in order to record the vigorous aftershock sequences. In this study we use data from the temporary seismic stations to re-locate all Oklahoma earthquakes in the USGS National Earthquake Information Center catalog using a multiple-event approach known as hypo-centroidal decomposition that locates earthquakes with decreased uncertainty relative to one another. Modeling from this study allows us to constrain the detailed geometry of the reactivated faults, as well as source parameters (focal mechanisms, stress drop, rupture length) for the larger earthquakes. Preliminary results from the November 2011 Prague sequence suggest that subsurface rupture lengths of the largest earthquakes are anomalously long with very low stress drop. We also observe very high Q (~1000 at 1 Hz) that explains the large felt areas and we find relatively low b-value and a rapid decay of aftershocks.

  4. Multiple event location analysis of aftershock sequences in the Pannonian basin

    NASA Astrophysics Data System (ADS)

    Bekesi, Eszter; Sule, Balint; Bondar, Istvan

    2016-04-01

    Accurate seismic event location is crucial to understand tectonic processes such as crustal faults that are most commonly investigated by studying seismic activity. Location errors can be significantly reduced using multiple event location methods. We applied the double difference method to relocate the earthquake occurred near Oroszlány and its 200 aftershocks to identify the geometry of the related fault. We used the extended ISC location algorithm, iLoc to determine the absolute single event locations for the Oroszlány aftershock sequence and applied double difference algorithm on the new hypocenters. To improve location precision, we added differential times from waveform cross-correlation to the multiple event location process to increase the accuracy of arrival time readings. We also tested the effect of various local 1-D velocity models on the results. We compared hypoDD results of bulletin and iLoc hypocenters to investigate the effect of initial hypocenter parameters on the relocation process. We show that hypoDD collapses the initial, rather diffuse locations into a smaller cluster and the vertical cross-sections show sharp images of seismicity. Unsurprisingly, the combined use of catalog and cross-correlation data sets provides the more accurate locations. Some of the relocated events in the cluster are ground truth quality with a location accuracy of 5 km or better. Having achieved accurate locations for the event cluster we are able to resolve the fault plane ambiguity in the moment tensor solutions and determine the accurate strike of the fault.

  5. Seismicity analysis of the Kachchh aftershock zone and tectonic implication for 26 Jan 2001 Bhuj earthquake

    NASA Astrophysics Data System (ADS)

    Bhatt, Kaushalendra Mangal; Hördt, Andreas; Kumar, Santosh

    2009-02-01

    We have carried out a detailed analysis of seismicity in the vicinity of the 26 Jan 2001 Bhuj earthquake (Mw 7.7). From the depth sections of 24 parallel profiles, and from the b-value cross section, we claim the existence of a hidden fault which conjugates to the major rupture fault (i.e. North Wagad Fault) of the 2001 Bhuj earthquake. The proximity of the intersection of these faults to the focus suggests a close association Bhuj main shock generation. A circular pattern in the profiles also provides evidence for the existence of an intrusive, consistent with earlier findings from gravity-magnetic modeling and tomography studies. The location of the fault intersection within the intrusive support a model where both play a significant role in the earthquake generation. The intersection of the conjugate faults acts as a stress concentrator, while their presence within a big pluton possibly will facilitate the stress amplification. This mechanism might explain the occurrence of two Mw = 7.7 earthquakes in a relatively short time span of 182 years in the Kachchh rift. The b-value cross section displays high and low b-value patches along the two intersecting faults. This suggests a model of a faulted block that consists of two kinds of segment, the locked and the unlocked. Locked segments do not easily participate in creeping and therefore generate strong magnitude aftershocks (M > 3) while unlocked segments easily creep and result in only weak aftershocks (M < 3). The different fault segments with weak and strong magnitude gathers will result in high and low b-values, respectively.

  6. The 11 April 2012 east Indian Ocean earthquake triggered large aftershocks worldwide

    USGS Publications Warehouse

    Pollitz, Fred F.; Stein, Ross S.; Sevilgen, Volkan; Burgmann, Roland

    2012-01-01

    Large earthquakes trigger very small earthquakes globally during passage of the seismic waves and during the following several hours to days1, 2, 3, 4, 5, 6, 7, 8, 9, 10, but so far remote aftershocks of moment magnitude M≥5.5 have not been identified11, with the lone exception of an M=6.9 quake remotely triggered by the surface waves from an M=6.6 quake 4,800 kilometres away12. The 2012 east Indian Ocean earthquake that had a moment magnitude of 8.6 is the largest strike-slip event ever recorded. Here we show that the rate of occurrence of remote M≥5.5 earthquakes (>1,500 kilometres from the epicentre) increased nearly fivefold for six days after the 2012 event, and extended in magnitude to M≥7. These global aftershocks were located along the four lobes of Love-wave radiation; all struck where the dynamic shear strain is calculated to exceed 10-7 for at least 100 seconds during dynamic-wave passage. The other M≥8.5 mainshocks during the past decade are thrusts; after these events, the global rate of occurrence of remote M≥5.5 events increased by about one-third the rate following the 2012 shock and lasted for only two days, a weaker but possibly real increase. We suggest that the unprecedented delayed triggering power of the 2012 earthquake may have arisen because of its strike-slip source geometry or because the event struck at a time of an unusually low global earthquake rate, perhaps increasing the number of nucleation sites that were very close to failure.

  7. Utility of a Three-Dimensional Interactive Augmented Reality Program for Balance and Mobility Rehabilitation in the Elderly: A Feasibility Study

    PubMed Central

    Im, Dal Jae; Ku, Jeunghun; Kim, Yeun Joon; Cho, Sangwoo; Cho, Yun Kyung; Lim, Teo; Lee, Hye Sun; Kim, Hyun Jung

    2015-01-01

    Objective To improve lower extremity function and balance in elderly persons, we developed a novel, three-dimensional interactive augmented reality system (3D ARS). In this feasibility study, we assessed clinical and kinematic improvements, user participation, and the side effects of our system. Methods Eighteen participants (age, 56-76 years) capable of walking independently and standing on one leg were recruited. The participants received 3D ARS training during 10 sessions (30-minute duration each) for 4 weeks. Berg Balance Scale (BBS) and the Timed Up and Go (TUG) scores were obtained before and after the exercises. Outcome performance variables, including response time and success rate, and kinematic variables, such as hip and knee joint angle, were evaluated after each session. Results Participants exhibited significant clinical improvements in lower extremity balance and mobility following the intervention, as shown by improved BBS and TUG scores (p<0.001). Consistent kinematic improvements in the maximum joint angles of the hip and knee were observed across sessions. Outcome performance variables, such as success rate and response time, improved gradually across sessions, for each exercise. The level of participant interest also increased across sessions (p<0.001). All participants completed the program without experiencing any adverse effects. Conclusion Substantial clinical and kinematic improvements were observed after applying a novel 3D ARS training program, suggesting that this system can enhance lower extremity function and facilitate assessments of lower extremity kinematic capacity. PMID:26161353

  8. Mobile-ip Aeronautical Network Simulation Study

    NASA Technical Reports Server (NTRS)

    Ivancic, William D.; Tran, Diepchi T.

    2001-01-01

    NASA is interested in applying mobile Internet protocol (mobile-ip) technologies to its space and aeronautics programs. In particular, mobile-ip will play a major role in the Advanced Aeronautic Transportation Technology (AATT), the Weather Information Communication (WINCOMM), and the Small Aircraft Transportation System (SATS) aeronautics programs. This report presents the results of a simulation study of mobile-ip for an aeronautical network. The study was performed to determine the performance of the transmission control protocol (TCP) in a mobile-ip environment and to gain an understanding of how long delays, handoffs, and noisy channels affect mobile-ip performance.

  9. Aftershocks of the 2010 Mw 7.4 Bonin Islands normal-faulting earthquake: Implication for deformation of the Pacific Plate

    NASA Astrophysics Data System (ADS)

    Obana, K.; Takahashi, T.; No, T.; Kaiho, Y.; Kodaira, S.; Yamashita, M.; Sato, T.; Noguchi, N.; Nakamura, T.

    2011-12-01

    A Mw 7.4 normal-faulting earthquake occurred 150 km east of Chichi-jima Island, Bonin Islands, Japan on December 21, 2010 (UTC). This is an earthquake occurred within the Pacific plate beneath the outer trench-slope region along the Izu-Ogasawara (Bonin) trench, where the Pacific plate subducts beneath the Philippine Sea plate. According to Japan Meteorological Agency (JMA), the associated tsunami was observed over a wide area along the Pacific coast of Japan. Normal faulting earthquakes in outer trench-slope region are a result of the bending of the incoming/subducting oceanic plates. The bending-related normal faults cutting the oceanic plate are likely associated with hydration of the oceanic plate prior to subduction [e.g., Ranero et al., 2003]. The normal faulting earthquakes can be a key to understand deformation and resulting hydration of the oceanic plate. That is also important for consideration of tsunami generation in shallow outer trench-slope region. Aftershock observation of the 2010 Bonin Islands earthquake were conducted by R/V Kairei of Japan Agency for Marine-Earth Science and Technology (JAMSTEC) using ocean bottom seismographs (OBSs). First OBS was deployed in the source area on December 25, 2010 and retrieved on January 7, 2011. Other 4 OBSs were deployed on January 6 and 7 and retrieved on March 11 and 12, 2011. Overall aftershocks distributed in a 130 km long area extended in a NW-SE direction although Izu-Bonin trench extends N-S direction in this area. Most of the aftershocks were located at depths shallower than 30 km, corresponding to the oceanic crust and the uppermost mantle of the Pacific plate. The aftershocks show a complicated distribution. In the central part of the aftershock area, aftershocks formed three subparallel lines with roughly 15 km intervals oriented NW-SE direction. In the southeastern part of the aftershock area away from the trench, the aftershocks distributed along ESE-WNW direction. We estimated aftershock

  10. The 3-D aftershock distribution of three recent M5~5.5 earthquakes in the Anza region,California

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Wdowinski, S.; Lin, G.

    2011-12-01

    The San Jacinto fault zone (SJFZ) exhibits the highest level of seismicity compared to other regions in southern California. On average, it produces four earthquakes per day, most of them at depth of 10-17 km. Over the past decade, an increasing seismic activity occurred in the Anza region, which included three M5~5.5 events and their aftershock sequences. These events occurred in 2001, 2005, and 2010. In this research we map the 3-D distribution of these three events to evaluate their rupture geometry and better understand the unusual deep seismic pattern along the SJFZ, which was termed "deep creep" (Wdowinski, 2009). We relocated 97,562 events from 1981 to 2011 in Anza region by applying the Source-Specific Station Term (SSST) method (Lin et al., 2006) and used an accurate 1-D velocity model derived from 3-D model of Lin et al (2007) and used In order to separate the aftershock sequence from background seismicity, we characterized each of the three aftershock sequences using Omori's law. Preliminary results show that all three sequences had a similar geometry of deep elongated aftershock distribution. Most aftershocks occurred at depth of 10-17 km and extended over a 70 km long segments of the SJFZ, centered at the mainshock hypocenters. A comparative study of other M5~5.5 mainshocks and their aftershock sequences in southern California reveals very different geometrical pattern, suggesting that the three Anza M5~5.5 events are unique and can be indicative of "deep creep" deformation processes. Reference 1.Lin, G.and Shearer,P.M.,2006, The COMPLOC earthquake location package,Seism. Res. Lett.77, pp.440-444. 2.Lin, G. and Shearer, P.M., Hauksson, E., and Thurber C.H.,2007, A three-dimensional crustal seismic velocity model for southern California from a composite event method,J. Geophys.Res.112, B12306, doi: 10.1029/ 2007JB004977. 3.Wdowinski, S. ,2009, Deep creep as a cause for the excess seismicity along the San Jacinto fault, Nat. Geosci.,doi:10.1038/NGEO684.

  11. Application of Subspace Detection to the 6 November 2011 M5.6 Prague, Oklahoma Aftershock Sequence

    NASA Astrophysics Data System (ADS)

    McMahon, N. D.; Benz, H.; Johnson, C. E.; Aster, R. C.; McNamara, D. E.

    2015-12-01

    Subspace detection is a powerful tool for the identification of small seismic events. Subspace detectors improve upon single-event matched filtering techniques by using multiple orthogonal waveform templates whose linear combinations characterize a range of observed signals from previously identified earthquakes. Subspace detectors running on multiple stations can significantly increasing the number of locatable events, lowering the catalog's magnitude of completeness and thus providing extraordinary detail on the kinematics of the aftershock process. The 6 November 2011 M5.6 earthquake near Prague, Oklahoma is the largest earthquake instrumentally recorded in Oklahoma history and the largest earthquake resultant from deep wastewater injection. A M4.8 foreshock on 5 November 2011 and the M5.6 mainshock triggered tens of thousands of detectable aftershocks along a 20 km splay of the Wilzetta Fault Zone known as the Meeker-Prague fault. In response to this unprecedented earthquake, 21 temporary seismic stations were deployed surrounding the seismic activity. We utilized a catalog of 767 previously located aftershocks to construct subspace detectors for the 21 temporary and 10 closest permanent seismic stations. Subspace detection identified more than 500,000 new arrival-time observations, which associated into more than 20,000 locatable earthquakes. The associated earthquakes were relocated using the Bayesloc multiple-event locator, resulting in ~7,000 earthquakes with hypocentral uncertainties of less than 500 m. The relocated seismicity provides unique insight into the spatio-temporal evolution of the aftershock sequence along the Wilzetta Fault Zone and its associated structures. We find that the crystalline basement and overlying sedimentary Arbuckle formation accommodate the majority of aftershocks. While we observe aftershocks along the entire 20 km length of the Meeker-Prague fault, the vast majority of earthquakes were confined to a 9 km wide by 9 km deep

  12. 3D imaging of crustal structure under the Piedmont province in central Virginia, from reflection RVSP processing of aftershock recordings from the August 23, 2011 Virginia earthquake

    NASA Astrophysics Data System (ADS)

    Quiros, D. A.; Brown, L. D.; Cabolova, A.; Davenport, K. K.; Hole, J. A.; Mooney, W. D.

    2013-12-01

    Aftershocks from the magnitude Mw 5.8 August 23, 2011, central Virginia earthquake were recorded using an unusually dense array of seismometers in what has been termed an AIDA (Aftershock Imaging with Dense Arrays) deployment. Over 200 stations were deployed in the epicentral region of this event to a) more precisely determine hypocentral locations, b) more accurately define velocity structure in the aftershock zone, c) characterize propagation characteristics of the crust in the area, and d) image geologic structures in the hypocentral volume with reflection techniques using aftershocks as sources. The AIDA-Virginia experiment successfully recorded a large number of aftershocks from which local tomographic velocity estimates and accurate hypocentral locations were obtained. These results facilitated the use of aftershocks as sources for reflection imaging. In this study we demonstrate how earthquake sources recorded by surface arrays can be treated using the imaging techniques associated with Vertical Seismic Profiling (VSP), in particular a variant known as Reverse VSP (RVSP). The central VSP processing algorithms used for this study are VSP normal moveout (VSPnmo) and VSP-to-Common Reflection Point (CRP). Applying these techniques to individual aftershocks from the Virginia experiment results in 3D reflection images of structural complexity in the immediate vicinity of the aftershocks. The most prominent feature observed on these 3D images is a strong moderately east-dipping reflector at a depth of approximately 6 to 8 km that directly underlies, and is continuous beneath, the more steeply dipping aftershock zone. We interpret this reflector as part of a complex imbricate thrust sequence associated with Paleozoic convergence during the Appalachian orogeny. Its apparent continuity beneath the fault zone implied by the aftershock's hypocenters suggests that this inferred fault zone has little or no cumulative offset, supporting the speculation that this event

  13. The 2012 August 11 MW 6.5, 6.4 Ahar-Varzghan earthquakes, NW Iran: aftershock sequence analysis and evidence for activity migration

    NASA Astrophysics Data System (ADS)

    Rezapour, Mehdi

    2016-02-01

    The Ahar-Varzghan doublet earthquakes with magnitudes MW 6.5 and 6.4 occurred on 2012 August 11 in northwest Iran and were followed by many aftershocks. In this paper, we analyse ˜5 months of aftershocks of these events. The Ahar-Varzghan earthquakes occurred along complex faults and provide a new constraint on the earthquake hazard in northwest Iran. The general pattern of relocated aftershocks defines a complex seismic zone covering an area of approximately 25 × 10 km2. The Ahar-Varzghan aftershock sequence shows a secondary activity which started on November 7, approximately 3 months after the main shocks, with a significant increase in activity, regarding both number of events and their magnitude. This stage was characterized by a seismic zone that propagated to the west of the main shocks. The catalogue of aftershocks for the doublet earthquake has a magnitude completeness of Mc 2.0. A below-average b-value for the Ahar-Varzghan sequence indicates a structural heterogeneity in the fault plane and the compressive stress state of the region. Relocated aftershocks occupy a broad zone clustering east-west with near-vertical dip which we interpret as the fault plane of the first of the doublet main shocks (MW 6.5). The dominant depth range of the aftershocks is from 3 to about 20 km, and the focal depths decrease toward the western part of the fault. The aftershock activity has its highest concentration in the eastern and middle parts of the active fault, and tapers off toward the western part of the active fault segment, indicating mainly a unilateral rupture toward west.

  14. A case study of two M~5 mainshocks in Anza, California: Is the footprint of an aftershock sequence larger than we think?

    USGS Publications Warehouse

    Fritts, Karen R.; Kilb, Debi

    2009-01-01

    It has been traditionally held that aftershocks occur within one to two fault lengths of the mainshock. Here we demonstrate that this perception has been shaped by the sensitivity of seismic networks. The 31 October 2001 Mw 5.0 and 12 June 2005 Mw 5.2 Anza mainshocks in southern California occurred in the middle of the densely instrumented ANZA seismic network and thus were unusually well recorded. For the June 2005 event, aftershocks as small as M 0.0 could be observed stretching for at least 50 km along the San Jacinto fault even though the mainshock fault was only ∼4.5 km long. It was hypothesized that an observed aseismic slipping patch produced a spatially extended aftershock-triggering source, presumably slowing the decay of aftershock density with distance and leading to a broader aftershock zone. We find, however, the decay of aftershock density with distance for both Anza sequences to be similar to that observed elsewhere in California. This indicates there is no need for an additional triggering mechanism and suggests that given widespread dense instrumentation, aftershock sequences would routinely have footprints much larger than currently expected. Despite the large 2005 aftershock zone, we find that the probability that the 2005 Anza mainshock triggered the M 4.9 Yucaipa mainshock, which occurred 4.2 days later and 72 km away, to be only 14%±1%. This probability is a strong function of the time delay; had the earthquakes been separated by only an hour, the probability of triggering would have been 89%.

  15. IUD discontinuation rates, switching behavior, and user satisfaction: findings from a retrospective analysis of a mobile outreach service program in Pakistan

    PubMed Central

    Azmat, Syed Khurram; Hameed, Waqas; Mustafa, Ghulam; Hussain, Wajahat; Ahmed, Aftab; Bilgrami, Mohsina

    2013-01-01

    Background In Pakistan, the uptake rate for the intrauterine device (IUD) is very low at 2.5%. The most popular modern contraceptive methods in Pakistan are female sterilization and use of condoms. The Marie Stopes Society established its mobile outreach service delivery program with the aim of increasing use of modern quality contraceptive services, including the long-term reversible IUD, by women living in hard-to-reach areas. The present study attempts to assess IUD discontinuation rates and associated factors, including switching behavior and level of satisfaction with this type of service delivery. Methods Using a cross-sectional approach, we contacted 681 women who had received an IUD from the Marie Stopes Society mobile outreach program during July and August 2009. Successful interviews were conducted with 639 of these women using a structured questionnaire. The data were analyzed with Stata 11.2 using simple descriptive Chi-square and Cox proportional techniques. Results Analysis revealed that 19.4% (95% confidence interval 16.3–22.5) of the women discontinued use of their IUD at 10 months and, of these women, the majority (69.4%) cited side effects as the main reason for discontinuation. Other factors, such as geographical catchment province, age of the woman, history of contraceptive use before IUD insertion, and side effects following insertion of the device, were found to be significantly associated with IUD. Amongst the women who had their IUD removed, 56.5% did not switch to any other contraceptive method, while 36.3% switched to either short-term or traditional methods, such as withdrawal, rhythm, and folk methods. Degree of satisfaction with the device was also significantly associated with discontinuation. Conclusion Early discontinuation and not switching to another contraceptive method increases the risk of unplanned pregnancy. Health care workers should be trained in managing clients’ concerns about the IUD to prevent discontinuation and

  16. Increasing lengths of aftershock zones with depths of moderate-size earthquakes on the San Jacinto Fault suggests triggering of deep creep in the middle crust

    NASA Astrophysics Data System (ADS)

    Meng, Xiaofeng; Peng, Zhigang

    2016-01-01

    Recent geodetic studies along the San Jacinto Fault (SJF) in southern California revealed a shallower locking depth than the seismogenic depth outlined by microseismicity. This disagreement leads to speculations that creeping episodes drive seismicity in the lower part of the seismogenic zone. Whether deep creep occurs along the SJF holds key information on how fault slips during earthquake cycle and potential seismic hazard imposed to southern California. Here we apply a matched filter technique to 10 M > 4 earthquake sequences along the SJF since 2000 and obtain more complete earthquake catalogues. We then systematic investigate spatio-temporal evolutions of these aftershock sequences. We find anomalously large aftershock zones for earthquakes occurred below the geodetically inferred locking depth (i.e. 11-12 km), while aftershock zones of shallower main shocks are close to expectations from standard scaling relationships. Although we do not observe clear migration of aftershocks, most aftershock zones do expand systematically with logarithmic time since the main shock. All the evidences suggest that aftershocks near or below the locking depth are likely driven by deep creep following the main shock. The presence of a creeping zone below 11-12 km may have significant implications on the maximum sizes of events in this region.

  17. Shape of the plate interface near the Mejillones Peninsula in Northern Chile inferred from high resolution relocation of Tocopilla aftershocks

    NASA Astrophysics Data System (ADS)

    Fuenzalida, A.; Schurr, B.; Lancieri, M.; Madariaga, R. I.

    2011-12-01

    The 14 November, Mw 7.8 2007 Tocopilla earthquake broke the southern part of seismic gap of northern Chile. The earthquake broke a rupture area 130 km by 30km along the deep plate interface between the Nazca and South American plates.The aftershock of this event were very well recorded by the IPOC (GFZ-IPGP-DGF) and Task Force networks (GFZ). Since the IPOC network was installed before the main Tocopilla earthquake we could locate the first two weeks of aftershocks with low accuracy.The first two weeks of aftershocks were characterised by a strong seismicity in the southern area starting with two big events of Mw 6.8 and 6.3 one day after the Tocopilla earthquake. On 29 November 2007 a Task Force (TF) Network of 20 short period instruments was installed by the GFZ team in the area of the Mejillones Peninsula. On 16 December a large Mw 6.8 slab push event took place at the center of this network. This event broke the oceanic crust of the subducted Nazca plate.(see Ruiz and Madariaga, this meeting). We have analysed in detail the TF data from its installation to 20 December. Hypocentral locations of the sequence were computed by automatic identification of the aftershocks and careful hand made readings of the arrival times of P and S phases for each seismogram. In a first study, we used the the nonlinear location software,NonLinLoc of Anthony Lomax using both a 1D model proposed by Husen from the study of earlier events in the region and the 2D model proposed by Patzwall et al from seismic profiles across the Mejillones Peninsula. We find that aftershocks were located along a thin, clearly defined zone that we interpret as the plate interface. As expected events situated off-shore of the Mejillones peninsula are less well located by Nonlinloc although our results suggest that several of these events occurred above the plate interface in the South American wedge. In a second step we relocated 850 events using the HypoDD method of Waldhauser et al with time delays

  18. Private Schools. Goin' Mobile.

    ERIC Educational Resources Information Center

    Miller, Laura

    1995-01-01

    To give children of migrant farm workers an academic boost, teachers at one Roman Catholic elementary school became mobile, following them to their destinations and offering a sense of stability to the Mexican and Mexican American students. The program integrates Mexican culture and Spanish language and provides outreach to families. (SM)

  19. The impact of static stress change, dynamic stress change, and the background stress on aftershock focal mechanisms

    USGS Publications Warehouse

    Hardebeck, Jeanne L.

    2014-01-01

    The focal mechanisms of earthquakes in Southern California before and after four M ≥ 6.7 main shocks provide insight into how fault systems respond to stress and changes in stress. The main shock static stress changes have two observed impacts on the seismicity: changing the focal mechanisms in a given location to favor those aligned with the static stress change and changing the spatial distribution of seismicity to favor locations where the static stress change aligns with the background stress. The aftershock focal mechanisms are significantly aligned with the static stress changes for absolute stress changes of ≥ 0.02 MPa, for up to ~20 years following the main shock. The dynamic stress changes have similar, although smaller, effects on the local focal mechanisms and the spatial seismicity distribution. Dynamic stress effects are best observed at long periods (30–60 s) and for metrics based on repeated stress cycling in the same direction. This implies that dynamic triggering operates, at least in part, through cyclic shear stress loading in the direction of fault slip. The background stress also strongly controls both the preshock and aftershock mechanisms. While most aftershock mechanisms are well oriented in the background stress field, 10% of aftershocks are identified as poorly oriented outliers, which may indicate limited heterogeneity in the postmain shock stress field. The fault plane orientations of the outliers are well oriented in the background stress, while their slip directions are not, implying that the background stress restricts the distribution of available fault planes.

  20. Double-difference Relocation of the Aftershocks of the Tecomán, Colima, Mexico Earthquake of 22 January 2003

    NASA Astrophysics Data System (ADS)

    Andrews, Vanessa; Stock, Joann; Ramírez Vázquez, Carlos Ariel; Reyes-Dávila, Gabriel

    2011-08-01

    On 22 January 2003, the M w = 7.6 Tecomán earthquake struck offshore of the state of Colima, Mexico, near the diffuse triple junction between the Cocos, Rivera, and North American plates. Three-hundred and fifty aftershocks of the Tecomán earthquake with magnitudes between 2.6 and 5.8, each recorded by at least 7 stations, are relocated using the double difference method. Initial locations are determined using P and S readings from the Red Sismológica Telemétrica del Estado de Colima (RESCO) and a 1-D velocity model. Because only eight RESCO stations were operating immediately following the Tecomán earthquake, uncertainties in the initial locations and depths are fairly large, with average uncertainties of 8.0 km in depth and 1.4 km in the north-south and east-west directions. Events occurring between 24 January and 31 January were located using not only RESCO phase readings but also additional P and S readings from 11 temporary stations. Average uncertainties decrease to 0.8 km in depth, 0.3 km in the east-west direction, and 0.7 km in the north-south direction for events occurring while the temporary stations were deployed. While some preliminary studies of the early aftershocks suggested that they were dominated by shallow events above the plate interface, our results place the majority of aftershocks along the plate interface, for a slab dipping between approximately 20° and 30°. This is consistent with the slab positions inferred from geodetic studies. We do see some upper plate aftershocks that may correspond to forearc fault zones, and faults inland in the upper plate, particularly among events occurring more than 3 months after the mainshock.

  1. Detailed velocity ratio mapping during the aftershock sequence as a tool to monitor the fluid activity within the fault plane

    NASA Astrophysics Data System (ADS)

    Bachura, Martin; Fischer, Tomáš

    2016-11-01

    The rheological properties of Earth materials are expressed by their seismic velocities and VP /VS ratio, which is easily obtained by the Wadati method. Its double-difference version based on cross-correlated waveforms enables focusing on very local structures and allows tracking, monitoring and analysing the fluid activity along faults. We applied the method to three 2014 mainshock-aftershock sequences in the West Bohemia/Vogtland (Czech Republic) earthquake swarm area and found pronounced VP /VS variations in time and space for different clusters of events located on a steeply dipping fault zone at depths ranging from 7 to 11 km. Each cluster reflects the spatial distribution of earthquakes along the fault plane but also the temporal evolution of the activity. Low values of VP /VS ratio down to 1.59 ± 0.02 were identified in the deeper part of the fault zone whereas higher values up to 1.73 ± 0.01 were estimated for clusters located on a shallower segment of the fault. Temporally the low VP /VS values are associated with the early aftershocks, while the higher VP /VS ratios are related only to later aftershocks. We interpret this behaviour as a result of saturation of the focal zone by compressible fluids: in the beginning the mainshock and early aftershocks driven by over-pressured fluids increased the porosity due to opening the fluid pathways. This process was associated with a decrease of the velocity ratio. In later stages the pressure and porosity decreased and the velocity ratio recovered to levels of 1.73, typical for a Poissonian medium and Earth's crust.

  2. Exponential decline of aftershocks of the M7.9 1868 great Kau earthquake, Hawaii, through the 20th century

    USGS Publications Warehouse

    Klein, F.W.; Wright, Tim

    2008-01-01

    The remarkable catalog of Hawaiian earthquakes going back to the 1820s is based on missionary diaries, newspaper accounts, and instrumental records and spans the great M7.9 Kau earthquake of April 1868 and its aftershock sequence. The earthquake record since 1868 defines a smooth curve complete to M5.2 of the declining rate into the 21st century, after five short volcanic swarms are removed. A single aftershock curve fits the earthquake record, even with numerous M6 and 7 main shocks and eruptions. The timing of some moderate earthquakes may be controlled by magmatic stresses, but their overall long-term rate reflects one of aftershocks of the Kau earthquake. The 1868 earthquake is, therefore, the largest and most controlling stress event in the 19th and 20th centuries. We fit both the modified Omori (power law) and stretched exponential (SE) functions to the earthquakes. We found that the modified Omori law is a good fit to the M ??? 5.2 earthquake rate for the first 10 years or so and the more rapidly declining SE function fits better thereafter, as supported by three statistical tests. The switch to exponential decay suggests that a possible change in aftershock physics may occur from rate and state fault friction, with no change in the stress rate, to viscoelastic stress relaxation. The 61-year exponential decay constant is at the upper end of the range of geodetic relaxation times seen after other global earthquakes. Modeling deformation in Hawaii is beyond the scope of this paper, but a simple interpretation of the decay suggests an effective viscosity of 1019 to 1020 Pa s pertains in the volcanic spreading of Hawaii's flanks. The rapid decline in earthquake rate poses questions for seismic hazard estimates in an area that is cited as one of the most hazardous in the United States.

  3. Distribution of the largest aftershocks in branching models of triggered seismicity: theory of the universal Båth law.

    PubMed

    Saichev, A; Sornette, D

    2005-05-01

    Using the epidemic-type aftershock sequence (ETAS) branching model of triggered seismicity, we apply the formalism of generating probability functions to calculate exactly the average difference between the magnitude of a mainshock and the magnitude of its largest aftershock over all generations. This average magnitude difference is found empirically to be independent of the mainshock magnitude and equal to 1.2, a universal behavior known as Båth's law. Our theory shows that Båth's law holds only sufficiently close to the critical regime of the ETAS branching process. Allowing for error bars +/- 0.1 for Båth's constant value around 1.2, our exact analytical treatment of Båth's law provides new constraints on the productivity exponent alpha and the branching ratio n: 0.9 approximately < alpha < or =1. We propose a method for measuring alpha based on the predicted renormalization of the Gutenberg-Richter distribution of the magnitudes of the largest aftershock. We also introduce the "second Båth law for foreshocks:" the probability that a main earthquake turns out to be the foreshock does not depend on its magnitude rho.

  4. The M 7.7 Tocopilla earthquake and its aftershock sequence: deployment of a Task Force local network

    NASA Astrophysics Data System (ADS)

    Sobiesiak, M.; Eggert, S.; Woith, H.; Grosser, H.; Peyrat, S.; Vilotte, J.; Medina, E.; Ruch, J.; Walter, T.; Victor, P.; Barrientos, S.; Gonzalez, G.

    2008-05-01

    After the November 14, 2007 Tocopilla earthquake in northern Chile, a local network of 20 short period seismic stations, 5 strong motion instruments, 6 GPS stations and 3 extensometers has been installed in the fault plane area between Tocopilla and Antofagasta by the German Task Force for earthquakes (GFZ Potsdam). The hydrogeology group of the TF sampled 20 thermal water sources in the area of the El Tatio geyser field, located about 170 km E of the epicentre. In collaboration with the IPG Paris, 4 broad band stations were deployed at the northern end of the fault plane between Tocopilla and Maria Elena. Major targets of the investigations of the aftershock sequence are the segment boundary between the 1995 Antofagasta earthquake and the recent Tocopilla event, stress transfer between both successively ruptured subduction zone segments, structural properties of the fault plane, possible consequences for the northern adjacent Iquique segment, and the influence of earthquake seismic waves on the El Tatio hydrothermal field. In our presentation we would like to show first results on the spatial distribution of the aftershocks and discuss these in relation to studies we have made on the Antofagasta aftershock sequence.

  5. Detailed source process of the 2007 Tocopilla earthquake and its main aftershocks

    NASA Astrophysics Data System (ADS)

    Peyrat, S.; Madariaga, R.; Buforn, E.; Meneses, G.; Campos, J.; Favreau, P.; Bernard, P.; Vilotte, J.

    2008-12-01

    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 teleseismic broadband and 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-CNRS, and of a digital strong- motion network operated by the University of Chile. The Tocopilla earthquake is the last large thrust subduction earthquake 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. The Tocopilla earthquake raises some disturbing questions: why this earthquake didn't extent further north ; what has been the role of the Mejillones peninsula in the south which seems to act as a barrier? We studied the detailed source process using the strong motion data available. The strong-motion data show clearly two S-waves arrivals, allowing the localization of two sources. The main shock started north of the segment close to Tocopilla. The rupture propagated southward. The second source was identified to start about 20 seconds later and located 50 km south from the hypocenter. The earthquake ruptured the interplate seismic zone over more than 150 km and generated several large aftershocks, mainly located south of the rupture area with the same focal mechanism, except for the largest one that took place on the 16 December. This event is a down-dip compressional event (slab push) placed down dip of the main interplate coupling zone at the southern end of the main event rupture zone. Finally in order to understand whether the northern gap has actually been reduced or not by the occurrence of the

  6. Electricomagnetic Coseismic signal associated with aftershock of Wenchuan Ms 8.0 earthquake

    NASA Astrophysics Data System (ADS)

    Tang, J.; Yan, Z.; Wang, L.; Dong, Z.; Guoze, Z.; Chen, X.; Qibin, X.; Wang, J.; Xu, G.

    2009-12-01

    The disastrous earthquake with magnitude Ms 8.0 had occurred in Wenchuan, Sichuan province at 14:28, May 12, 2008. Two sets MT system V5-2000 ware set up at Hanwang (HW) and Chouziba (CB) on May 22 and May 25 respectively in Wudu,Gansu province where is about 100 km away from Qingchang epicenter of aftershock zone. They are 3 km away from each other. The data recording with 24 Hz sampling rate had been done continuously except changing battery at 8:00 to 8:30 for 22 days and recorded many aftershocks events. 19 events were recorded at both measurement sites with magnitude bigger than Ms 4.0 in distance shorter than 120 km away from the observation sites during 22 days, including the biggest one Ms 6.4 in Qingchuan at 16:21, May 25. A seismometer with sampling rate 200 Hz was set up at Hanwang which is 2.5 km away from HW and 5.5 km from CB in order to compared electromagnetic wave variation. Both seismometer and MT system adopt GPS time service. It is easy to synchronize for both data. The coseismic signal obtained on all electric and magnetic field channels at both HW and CB site for most of events, but few events did not very significant on electric channels. We analysesed 120 seconds sampled data during event occurrence. The time series of both seismic wave and MT records show that co-seismic signals exist on all components of the magnetic and electric fields of two different sites, but that they begin with the arrival of seismic waves and not at the origin time of the earthquake. The most easily understood signals on all our sensors are always the co-seismic responses. These results are consistent with those of predecessor. It is very clear that co-seismic coseismic signals are not produced at the earthquake source, but rather are due to local effects of passing seismic waves. The visible co-seismic signal records the motion of the sensors in the earth’s magnetic field and also an electro-seismic component due to charge-separation induced by passage of the

  7. Continuity of the West Napa Fault Zone Inferred from Aftershock Recordings on Fault-Crossing Arrays

    NASA Astrophysics Data System (ADS)

    Catchings, R.; Goldman, M.; Slad, G. W.; Criley, C.; Chan, J. H.; Fay, R. P.; Fay, W.; Svitek, J. F.

    2014-12-01

    In an attempt to determine the continuity and lateral extent of the causative fault(s) of the 24 August 2014 Mw 6.0 Napa earthquake and possible interconnections with other mapped faults, we recorded aftershocks on three closely spaced (100 m) seismograph arrays that were positioned across the coseismic rupture zone and across mapped faults located north and south of coseismic rupture. Array 1 was located in northwest Napa, between Highway 29 and the intersection of Redwood and Mt. Veeder roads, array 2 was located southwest of Napa, ~1 km north of Cuttings Wharf, and array 3 was located south of San Pablo Bay, within the town of Alhambra. Our intent was to record high-amplitude guided waves that only travel within the causative fault zone and its extensions (Li and Vidale, 1996). Preliminary analysis of seismic data from an M 3.2 aftershock shows high-amplitude (up to 1 cm/s) seismic waves occurred on seismographs within 100 m of mapped surface ruptures and fault zones. Northwest of Napa, the high amplitudes along array 1 coincide with zones of structural damage and wide spread surface ground cracking, and along array 2 near Cuttings Wharf, the high amplitudes occur slightly east of surface ruptures seen along Los Amigas Road. We also observe relatively high-amplitude seismic waves across the Franklin Fault (array 3), approximately 32 km southeast of the mainshock epicenter; this observation suggests the West Napa and the Franklin faults may be continuous or connected. Existing fault maps show that the Franklin Fault extends at least 15 km southward to the Calaveras Fault zone and the West Napa Fault extends at least 25 km north of our array 1. Collectively, the mapped faults, surface ruptures, and guided waves suggest that the West Napa- Franklin Fault zone may extend more than 85 km before it merges with the Calaveras Fault. Assuming a continuous fault zone, the West Napa - Franklin Fault zone may be capable of generating a much larger magnitude earthquake that

  8. Testing the ability of different seismic detections approaches to monitor aftershocks following a moderate magnitude event.

    NASA Astrophysics Data System (ADS)

    Romero, Paula; Díaz, Jordi; Ruiz, Mario; Cantavella, Juan Vicente; Gomez-García, Clara

    2016-04-01

    The detection and picking of seismic events is a permanent concern for seismic surveying, in particular when dealing with aftershocks of moderate magnitude events. Many efforts have been done to find the balance between computer efficiency and the robustness of the detection methods. In this work, data recorded by a high density seismic network deployed following a 5.2 magnitude event located close to Albacete, SE Spain, is used to test the ability of classical and recently proposed detection methodologies. Two days after the main shock, occurred the 23th February, a network formed by 11 stations from ICTJA-CSIC and 2 stations from IGN were deployed over the region, with inter-station distances ranging between 5 and 10 km. The network remained in operation until April 6th, 2015 and allowed to manually identify up to 552 events with magnitudes from 0.2 to 3.5 located in an area of just 25 km2 inside the network limits. The detection methods here studied applied are the classical STA/LTA, a power spectral method, a detector based in the Benford's law and a waveform similarity method. The STA/LTA method, based in the comparison of background noise and seismic signal amplitudes, is taken as a reference to evaluate the results arising from the other approaches. The power spectral density method is based in the inspection of the characteristic frequency pattern associated to seismic events. The Benford's Law detector analyses the distribution of the first-digit of displacement count in the histogram of a seismic waveform, considering that only the windows containing seismic wave arrivals will match the logarithmic law. Finally, the waveform similarity method is based in the analysis of the normalized waveform amplitude, detecting those events with waveform similar to a previously defined master event. The aim of this contribution is to inspect the ability of the different approaches to accurately detect the aftershocks events for this kind of seismic crisis and to

  9. Short-term forecasting of aftershock sequences, microseismicity and swarms inside the Corinth Gulf continental rift

    NASA Astrophysics Data System (ADS)

    Segou, Margarita

    2014-05-01

    Corinth Gulf (Central Greece) is the fastest continental rift in the world with extension rates 11-15 mm/yr with diverse seismic deformation including earthquakes with M greater than 6.0, several periods of increased microseismic activity, usually lasting few months and possibly related with fluid diffusion, and swarm episodes lasting few days. In this study I perform a retrospective forecast experiment between 1995-2012, focusing on the comparison between physics-based and statistical models for short term time classes. Even though Corinth gulf has been studied extensively in the past there is still today a debate whether earthquake activity is related with the existence of either a shallow dipping structure or steeply dipping normal faults. In the light of the above statement, two CRS realization are based on resolving Coulomb stress changes on specified receiver faults, expressing the aforementioned structural models, whereas the third CRS model uses optimally-oriented for failure planes. The CRS implementation accounts for stress changes following all major ruptures with M greater than 4.5 within the testing phase. I also estimate fault constitutive parameters from modeling the response to major earthquakes at the vicinity of the gulf (Aσ=0.2, stressing rate app. 0.02 bar/yr). The generic ETAS parameters are taken as the maximum likelihood estimates derived from the stochastic declustering of the modern seismicity catalog (1995-2012) with minimum triggering magnitude M2.5. I test whether the generic ETAS can efficiently describe the aftershock spatio-temporal clustering but also the evolution of swarm episodes and microseismicity. For the reason above, I implement likelihood tests to evaluate the forecasts for their spatial consistency and for the total amount of predicted versus observed events with M greater than 3.0 in 10-day time windows during three distinct evaluation phases; the first evaluation phase focuses on the Aigio 1995 aftershock sequence (15

  10. Stress Triggering of Conjugate Normal Faulting: Late Aftershocks of the 1983 M 7.3 Borah Peak, Idaho Earthquake

    SciTech Connect

    Suzette J. Payne; James Zollweg; David Rodgers

    2004-06-01

    The 1984 Devil Canyon sequence was a late aftershock sequence of the 28 October 1983 Ms 7.3 Borah Peak, Idaho, earthquake. The sequence began on 22 August 1984 with the ML 5.8 Devil Canyon earthquake, which nucleated at a depth of 12.8 ± 0.7 km between the surface traces of two normal faults, the Challis segment of the Lost River fault and the Lone Pine fault. Two hundred thirty-seven aftershocks were recorded by a temporary array during a 3-week period. Their focal mechanisms and hypocenter distribution define a cross-sectional "V" pattern whose base corresponds to the ML 5.8 event, whose tips correspond to the exposed fault traces, and whose sides define two planar fault zones oriented N25°W, 75°SW (Challis fault segment) and N39°W, 58°NE (Lone Pine fault). This pattern describes a graben bounded by conjugate normal faults. Temporal aspects of the Devil Canyon sequence provide strong evidence that slip on conjugate normal faults occurs sequentially. Aftershocks occurred primarily along the Challis segment until the occurrence of the 8 September 1984 ML 5.0 earthquake along the Lone Pine fault, after which aftershocks primarily occurred along this fault. These observations are consistent with worldwide seismologic and geologic observations and with physical and numerical models of conjugate normal faulting. Aftershocks of the Devil Canyon sequence occurred immediately northwest of the ML 5.8 Devils Canyon earthquake, which itself was immediately northwest of the Thousand Springs segment of the Lost River fault (the fault that slipped in association with the Ms 7.3 Borah Peak earthquake). Coulomb failure stress analysis indicates that stress increases resulting from both the Borah Peak mainshock and Devil Canyon ML 5.8 earthquake were sufficient to induce failure on the Lone Pine fault. These space–time patterns suggest that conjugate normal faults may transfer stress or accommodate stress changes at the terminations of major normal faults in the Basin and

  11. Spatial stress variations in the aftershock sequence following the 2008 M6 earthquake doublet in the South Iceland Seismic Zone

    NASA Astrophysics Data System (ADS)

    Hensch, M.; Árnadóttir, Th.; Lund, B.; Brandsdóttir, B.

    2012-04-01

    The South Iceland Seismic Zone (SISZ) is an approximately 80 km wide E-W transform zone, bridging the offset between the Eastern Volcanic Zone and the Hengill triple junction to the west. The plate motion is accommodated in the brittle crust by faulting on many N-S trending right-lateral strike-slip faults of 2-5 km separation. Major sequences of large earthquakes (M>6) has occurred repeatedly in the SISZ since the settlement in Iceland more than thousand years ago. On 29th May 2008, two M6 earthquakes hit the western part of the SISZ on two adjacent N-S faults within a few seconds. The intense aftershock sequence was recorded by the permanent Icelandic SIL network and a promptly installed temporary network of 11 portable seismometers in the source region. The network located thousands of aftershocks during the following days, illuminating a 12-17 km long region along both major fault ruptures as well as several smaller parallel faults along a diffuse E-W trending region west of the mainshock area without any preceding main rupture. This episode is suggested to be the continuation of an earthquake sequence which started with two M6.5 and several M5-6 events in June 2000. The time delay between the 2000 and 2008 events could be due to an inflation episode in Hengill during 1993-1998, that potentially locked N-S strike slip faults in the western part of the SISZ. Around 300 focal solutions for aftershocks have been derived by analyzing P-wave polarities, showing predominantly strike-slip movements with occasional normal faulting components (unstable P-axis direction), which suggests an extensional stress regime as their driving force. A subsequent stress inversion of four different aftershock clusters reveals slight variations of the directions of the average σ3 axes. While for both southern clusters, including the E-W cluster, the σ3 axes are rather elongated perpendicular to the overall plate spreading axis, they are more northerly trending for shallower clusters

  12. Application of Mobile-ip to Space and Aeronautical Networks

    NASA Technical Reports Server (NTRS)

    Leung, Kent; Shell, Dan; Ivancic, William D.; Stewart, David H.; Bell, Terry L.; Kachmar, Brian A.

    2001-01-01

    The National Aeronautics and Space Administration (NASA) is interested in applying mobile Internet protocol (mobile-ip) technologies to its space and aeronautics programs. In particular, mobile-ip will play a major role in the Advanced Aeronautic Transportation Technology (AAT-F), the Weather Information Communication (WINCOMM), and the Small Aircraft Transportation System (SATS) aeronautics programs. This paper describes mobile-ip and mobile routers--in particular, the features, capabilities, and initial performance of the mobile router are presented. The application of mobile-router technology to NASA's space and aeronautics programs is also discussed.

  13. Inferring Aftershock Sequence Properties and Tectonic Structure Using Empirical Signal Detectors

    NASA Astrophysics Data System (ADS)

    Junek, William N.; Kværna, Tormod; Pirli, Myrto; Schweitzer, Johannes; Harris, David B.; Dodge, Douglas A.; Woods, Mark T.

    2015-02-01

    Seismotectonic studies of the 2008 Storfjorden aftershock sequence were limited to data acquired by the permanent, but sparse, regional seismic network in the Svalbard archipelago. Storfjorden's remote location and harsh polar environment inhibited deployment of temporary seismometers that would have improved observations of sequence events. The lack of good station coverage prevented the detection and computation of hypocenter locations of many low magnitude events (mb < 2.5) in the NORSAR analyst-reviewed bulletin. As a result, the fine structure of the sequence's space-time distribution was not captured. In this study, an autonomous event detection and clustering framework is employed to build a more complete catalog of Storfjorden events using data from the Spitsbergen (SPITS) array. The new catalog allows the spatiotemporal distribution of seismicity within the fjord to be studied in greater detail. Information regarding the location of active event clusters provides a means of inferring the tectonic structure within the fault zone. The distribution of active clusters and moment tensor solutions for the Storfjorden sequence suggests there are at least two different structures within the fjord: a NE-SW trending linear feature with oblique-normal to strike-slip faulting and E-W trending normal faults.

  14. The Hellenic Seismological Network of Crete (HSNC): validation and results of the 2013 aftershock sequences

    NASA Astrophysics Data System (ADS)

    Chatzopoulos, G.; Papadopoulos, I.; Vallianatos, F.

    2016-02-01

    The last century, the global urbanization has leaded the majority of population to move into big, metropolitan areas. Small areas on the Earth's surface are being built with tall buildings in areas close to seismogenic zones. Such an area of great importance is the Hellenic arc in Greece. Among the regions with high seismicity is Crete, located on the subduction zone of the Eastern Mediterranean plate underneath the Aegean plate. The Hellenic Seismological Network of Crete (HSNC) has been built to cover the need on continuous monitoring of the regional seismicity in the vicinity of the South Aegean Sea and Crete Island. In the present work, with the use of Z-map software the spatial variability of Magnitude of Completeness (Mc) is calculated from HSNC's manual analysis catalogue of events from the beginning of 2008 till the end of September 2015, supporting the good coverage of HSNC in the area surrounding Crete Island. Furthermore, we discuss the 2013 seismicity when two large earthquakes occurred in the vicinity of Crete Island. The two main shocks and their aftershock sequences have been relocated with the use of HYPOINVERSE earthquake location software. Finally, the quality of seismological stations is addressed using the standard PQLX software.

  15. Large-amplitude moho reflections (SmS) from Landers aftershocks, Southern California

    USGS Publications Warehouse

    Mori, J.; Helmberger, D.

    1996-01-01

    Closely spaced aftershocks of the 28 June 1992 Landers earthquake (Mw 7.3) were used to make event record sections that show the transverse components of 5 and SmS arrivals at a distance of 70 to 170 km. For the data recorded toward the north in the Mojave desert, large SmS phases are observed with amplitudes 2 to 5 times greater than the direct S. For similar distances to the south, the SmS arrival is comparable to or smaller than the S. Comparisons to synthetic seismograms indicate that the large-amplitude SmS phases are produced by the simple crustal structure of the Mojave desert that allows a large Moho reflection. In contrast, the more complex geologic structure to the south partitions the seismic energy into a more complicated set of seismic phases, so that the Moho reflection is diminished in amplitude. The large SmS phases observed in the Mojave enhance the overall ground motions by a factor of 2 to 3. This suggests that when damaging earthquakes occur in other regions of simple crustal structures, Moho reflections will produce amplified strong motions at distance ranges around 100 km depending on the local structure.

  16. Chapter D. The Loma Prieta, California, Earthquake of October 17, 1989 - Aftershocks and Postseismic Effects

    USGS Publications Warehouse

    Reasenberg, Paul A.

    1997-01-01

    While the damaging effects of the earthquake represent a significant social setback and economic loss, the geophysical effects have produced a wealth of data that have provided important insights into the structure and mechanics of the San Andreas Fault system. Generally, the period after a large earthquake is vitally important to monitor. During this part of the seismic cycle, the primary fault and the surrounding faults, rock bodies, and crustal fluids rapidly readjust in response to the earthquake's sudden movement. Geophysical measurements made at this time can provide unique information about fundamental properties of the fault zone, including its state of stress and the geometry and frictional/rheological properties of the faults within it. Because postseismic readjustments are rapid compared with corresponding changes occurring in the preseismic period, the amount and rate of information that is available during the postseismic period is relatively high. From a geophysical viewpoint, the occurrence of the Loma Prieta earthquake in a section of the San Andreas fault zone that is surrounded by multiple and extensive geophysical monitoring networks has produced nothing less than a scientific bonanza. The reports assembled in this chapter collectively examine available geophysical observations made before and after the earthquake and model the earthquake's principal postseismic effects. The chapter covers four broad categories of postseismic effect: (1) aftershocks; (2) postseismic fault movements; (3) postseismic surface deformation; and (4) changes in electrical conductivity and crustal fluids.

  17. Comparison of main-shock and aftershock fragility curves developed for New Zealand and US buildings

    USGS Publications Warehouse

    Uma, S.R.; Ryu, H.; Luco, N.; Liel, A.B.; Raghunandan, M.

    2011-01-01

    Seismic risk assessment involves the development of fragility functions to express the relationship between ground motion intensity and damage potential. In evaluating the risk associated with the building inventory in a region, it is essential to capture 'actual' characteristics of the buildings and group them so that 'generic building types' can be generated for further analysis of their damage potential. Variations in building characteristics across regions/countries largely influence the resulting fragility functions, such that building models are unsuitable to be adopted for risk assessment in any other region where a different set of building is present. In this paper, for a given building type (represented in terms of height and structural system), typical New Zealand and US building models are considered to illustrate the differences in structural model parameters and their effects on resulting fragility functions for a set of main-shocks and aftershocks. From this study, the general conclusion is that the methodology and assumptions used to derive basic capacity curve parameters have a considerable influence on fragility curves.

  18. Explanation of temporal clustering of tsunami sources using the epidemic-type aftershock sequence model

    USGS Publications Warehouse

    Geist, Eric L.

    2014-01-01

    Temporal clustering of tsunami sources is examined in terms of a branching process model. It previously was observed that there are more short interevent times between consecutive tsunami sources than expected from a stationary Poisson process. The epidemic‐type aftershock sequence (ETAS) branching process model is fitted to tsunami catalog events, using the earthquake magnitude of the causative event from the Centennial and Global Centroid Moment Tensor (CMT) catalogs and tsunami sizes above a completeness level as a mark to indicate that a tsunami was generated. The ETAS parameters are estimated using the maximum‐likelihood method. The interevent distribution associated with the ETAS model provides a better fit to the data than the Poisson model or other temporal clustering models. When tsunamigenic conditions (magnitude threshold, submarine location, dip‐slip mechanism) are applied to the Global CMT catalog, ETAS parameters are obtained that are consistent with those estimated from the tsunami catalog. In particular, the dip‐slip condition appears to result in a near zero magnitude effect for triggered tsunami sources. The overall consistency between results from the tsunami catalog and that from the earthquake catalog under tsunamigenic conditions indicates that ETAS models based on seismicity can provide the structure for understanding patterns of tsunami source occurrence. The fractional rate of triggered tsunami sources on a global basis is approximately 14%.

  19. The Constantine (northeast Algeria) earthquake of October 27, 1985: surface ruptures and aftershock study

    NASA Astrophysics Data System (ADS)

    Bounif, A.; Haessler, H.; Meghraoui, M.

    1987-10-01

    An earthquake of magnitude Ms = 6.0 (CSEM, Strasbourg) occurred at Constantine (Algeria) on 27 October 1985. This seismic event is the strongest felt in the Tellian Atlas since the El Asnam seismic crisis of October 10, 1980. A team from the Centre de Recherche d'Astronomie, d'Astrophysique et de Géophysique (CRAAG, Algeria), utilising 8 portable stations, registered the activity a few days after the main shock. The aftershocks follow a N045° direction, and show the existence of three ruptured segments. Cross sections display a remarkable vertical fault plane and suggest asperities in the rupture process. Surface breaks were found affecting Quaternary deposits. The principal segment is about 3.8 km long showing “enéchelon” cracks with left-lateral displacement while the main direction of the rupture is N055°. Although the vertical motion is small, the northwestern block shows a normal component of the main surface faulting, while the left-lateral displacement is about 10 cm. The strike-slip focal mechanism solution determined from the global seismic network and field observations are in good agreement.

  20. A Stochastic Estimate of Ground Motion at Oceano, California, for the M6.5 December 22, 2003, San Simeon Earthquake, Derived from Aftershock Recordings

    NASA Astrophysics Data System (ADS)

    di Alessandro, C.; Boatwright, J.

    2004-12-01

    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 M6.5 San Simeon earthquake. This station recorded 11 M\\> 2.8 aftershocks in almost eight weeks. We use these recordings, together with recordings of the main shock 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 a generalized spectral ratio analysis that averages the spectral ratios from both stations for all the co-recorded aftershocks. We test three aftershocks as Green's functions by comparing simulated and recorded acceleration amplitude spectra for the main shock at Park Hill and San Luis Obispo. Instead of deconvolving the aftershock recordings from the mainshock recordings to estimate a source-time function, we convolve the aftershock accelerograms with a stochastic operator to simulate the duration and phase of the mainshock accelerograms. These stochastic operators are determined as sets of delta functions whose delays are randomly generated from a gamma distribution with a shape parameter of 1. We choose the scale parameter by fitting Husid plots of the Park Hill and San Luis Obsipo mainshock accelerograms. This stochastic approach 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 main shock. Our realizations for the mainshock accelerogram at Oceano yield PGAs distributed as 28±4% g. We interpret these realizations as upper bounds for the actual ground motion because our analysis assumes that the ground behaved linearly, while the liquefaction and lateral spreading indicates that the ground behaved non-linearly. Geotechnical analysis of the site indicates that a PGA of 25% g would have initiated the liquefaction.

  1. Modeling Mobility

    NASA Astrophysics Data System (ADS)

    Berl, Andras

    In wireless networks, communication can take place based on an infrastructure (e.g. WLAN access point or GPRS base station) or it can take place in adhoc mode, where mobile devices are connected directly to each other and care for the routing by themselves (mobile ad-hoc networks). When such wireless networks are investigated and simulations are performed, it is often necessary to consider the movement of entities within the simulated environment.

  2. Some statistical features of the aftershock temporal behavior after the M7.4 Izmit earthquake of august 17, 1999 in Turkey

    NASA Astrophysics Data System (ADS)

    Gospodinov, D.; Fajtin, H.; Rangelov, B.; Marekova, E.

    2009-04-01

    An earthquake of magnitude Mw=7.4 struck 8 km. southeast of Izmit, Turkey at 3:02 AM local time on August 17, 1999. The earthquake occurred on one of the world's longest and best studied strike-slip (horizontal motion) faults - the east-west trending North Anatolian fault. Seismologists are not able to predict the timing and sizes of individual aftershocks but stochastic modeling allows determinationof probabilities for aftershocks and larger mainshocks duringintervals following the mainshock. The most widely applied stochastic model to depict aftershocks temporal distribution is the non- homogenous Poisson process with a decaying intensity, which follows the Modified Omori Formula (MOF) (Utsu, 1961). A more complex model, considering the triggering potential of each aftershock was developed by Ogata (1988) and it was named Epidemic Type Aftershock Sequence (ETAS) model. Gospodinov and Rotondi (2006) elaborated a Restricted Epidemic Type Aftershock Sequence (RETAS) model. The latter follows the general idea that only aftershocks stronger than some cut-off magnitude possess the capability to induce secondary aftershock activity. In this work we shall consider the Restricted Epidemic Type Aftershock Sequence (RETAS) model, for which the conditional intensity function turns out to be ‘ K0eα(Mi-M0)- λ (t|Ht) = + (t- ti + c)p ti < t Mi ≥ Mth (1) Here the summation occurs for all aftershocks with magnitude bigger than or equal to Mth, which took place before time. Leaving Mth to take all possible values, one can examine all RETAS model versions between the MOF and the ETAS model on the basis of the Akaike Information Criterion AIC (Akaike, 1974) AIC = - 2max log L+ 2k (2) where k is the number of parameters used in the model and logL is the logarithm of the likelihood function. Then for the model providing the best fit, we choose the one with the smallest AIC value. The purpose of this paper is to verify versions of the RETAS model (including the MOF and the

  3. Regulatory frameworks for mobile medical applications.

    PubMed

    Censi, Federica; Mattei, Eugenio; Triventi, Michele; Calcagnini, Giovanni

    2015-05-01

    A mobile application (app) is a software program that runs on mobile communication devices such as a smartphone. The concept of a mobile medical app has gained popularity and diffusion but its reference regulatory context has raised discussion and concerns. Theoretically, a mobile app can be developed and uploaded easily by any person or entity. Thus, if an app can have some effects on the health of the users, it is mandatory to identify its reference regulatory context and the applicable prescriptions.

  4. Modeling of Kashmir Aftershock Decay Based on Static Coulomb Stress Changes and Laboratory-Derived Rate-and-State Dependent Friction Law

    NASA Astrophysics Data System (ADS)

    Javed, F.; Hainzl, S.; Aoudia, A.; Qaisar, M.

    2016-05-01

    We model the spatial and temporal evolution of October 8, 2005 Kashmir earthquake's aftershock activity using the rate-and-state dependent friction model incorporating uncertainties in computed coseismic stress perturbations. We estimated the best possible value for frictional resistance " Aσ n", background seismicity rate " r" and coefficient of stress variation "CV" using maximum log-likelihood method. For the whole Kashmir earthquake sequence, we measure a frictional resistance Aσ n ~ 0.0185 MPa, r ~ 20 M3.7+ events/year and CV = 0.94 ± 0.01. The spatial and temporal forecasted seismicity rate of modeled aftershocks fits well with the spatial and temporal distribution of observed aftershocks that occurred in the regions with positive static stress changes as well as in the apparent stress shadow region. To quantify the effect of secondary aftershock triggering, we have re-run the estimations for 100 stochastically declustered catalogs showing that the effect of aftershock-induced secondary stress changes is obviously minor compared to the overall uncertainties, and that the stress variability related to uncertain slip model inversions and receiver mechanisms remains the major factor to provide a reasonable data fit.

  5. Analysis of rupture area of aftershocks caused by twin earthquakes (Case study: 11 April 2012 earthquakes of Aceh-North Sumatra)

    SciTech Connect

    Diansari, Angga Vertika Purwana, Ibnu; Subakti, Hendri

    2015-04-24

    The 11 April 2012 earthquakes off-shore Aceh-North Sumatra are unique events for the history of Indonesian earthquake. It is unique because that they have similar magnitude, 8.5 Mw and 8.1 Mw; close to epicenter distance, similar strike-slip focal mechanism, and occuring in outer rise area. The purposes of this research are: (1) comparing area of earthquakes base on models and that of calculation, (2) fitting the shape and the area of earthquake rupture zones, (3) analyzing the relationship between rupture area and magnitude of the earthquakes. Rupture area of the earthquake fault are determined by using 4 different formulas, i.e. Utsu and Seki (1954), Wells and Coppersmith (1994), Ellsworth (2003), and Christophersen and Smith (2000). The earthquakes aftershock parameters are taken from PGN (PusatGempabumiNasional or National Earthquake Information Center) of BMKG (Indonesia Agency Meteorology Climatology and Geophysics). The aftershock epicenters are plotted by GMT’s software. After that, ellipse and rectangular models of aftershock spreading are made. The results show that: (1) rupture areas were calculated using magnitude relationship which are larger than the the aftershock distributions model, (2) the best fitting model for that earthquake aftershock distribution is rectangular associated with Utsu and Seki (1954) formula, (3) the larger the magnitude of the earthquake, the larger area of the fault.

  6. 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.

  7. Did stress triggering cause the large off-fault aftershocks of the 25 March 1998 MW=8.1 Antarctic plate earthquake?

    USGS Publications Warehouse

    Toda, S.; Stein, R.S.

    2000-01-01

    The 1998 Antarctic plate earthquake produced clusters of aftershocks (MW ??? 6.4) up to 80 km from the fault rupture and up to 100 km beyond the end of the rupture. Because the mainshock occurred far from the nearest plate boundary and the nearest recorded earthquake, it is unusually isolated from the stress perturbations caused by other earthquakes, making it a good candidate for stress transfer analysis despite the absence of near-field observations. We tested whether the off-fault aftershocks lie in regions brought closer to Coulomb failure by the main rupture. We evaluated four published source models for the main rupture. In fourteen tests using different aftershocks sets and allowing the rupture sources to be shifted within their uncertainties, 6 were significant at ??? 99% confidence, 3 at > 95% confidence, and 5 were not significant (< 95% level). For the 9 successful tests, the stress at the site of the aftershocks was typically increased by 1-2 bars (0.1-0.2 MPa). Thus the Antarctic plate event, together with the 1992 MW=7.3 Landers and its MW=6.5 Big Bear aftershock 40 km from the main fault, supply evidence that small stress changes might indeed trigger large earthquakes far from the main fault rupture.

  8. Diversity of the 2014 Iquique's foreshocks and aftershocks: clues about the complex rupture process of a Mw 8.1 earthquake

    NASA Astrophysics Data System (ADS)

    León-Ríos, Sergio; Ruiz, Sergio; Maksymowicz, Andrei; Leyton, Felipe; Fuenzalida, Amaya; Madariaga, Raúl

    2016-03-01

    We study the foreshocks and aftershocks of the 1 April 2014 Iquique earthquake of Mw 8.1. Most of these events were recorded by a large digital seismic network that included the Northern Chile permanent network and up to 26 temporary broadband digital stations. We relocated and computed moment tensors for 151 events of magnitude Mw ≥ 4.5. Most of the foreshocks and aftershocks of the Iquique earthquake are distributed to the southwest of the rupture zone. These events are located in a band of about 50 km from the trench, an area where few earthquakes occur elsewhere in Chile. Another important group of aftershocks is located above the plate interface, similar to those observed during the foreshock sequence. The depths of these events were constrained by regional moment tensor (RMT) solutions obtained using the records of the dense broad band network. The majority of the foreshocks and aftershocks were associated to the interplate contact, with dip and strike angles in good agreement with the characteristics of horst and graben structures (>2000 m offset) typical of the oceanic Nazca Plate at the trench and in the outer rise region. We propose that the spatial distribution of foreshocks and aftershocks, and its seismological characteristics were strongly controlled by the rheological and tectonics conditions of the extreme erosive margin of Northern Chile.

  9. Wavefield polarization in seismograms of Darfield aftershocks: orthogonality relation with shear wave velocity anisotropy

    NASA Astrophysics Data System (ADS)

    Pischiutta, M.; Savage, M. K.; Rovelli, A.; Holt, R. A.; Syracuse, E. M.; Thurber, C. H.

    2012-12-01

    The Greendale fault was discovered after the 7.2 magnitude earthquake that occurred on September 4, 2010 at Darfield, New Zealand. It is a right-lateral strike slip fault that released an average slip of 2.5m during the main shock. In previous works, the presence of structure/stress induced anisotropy was investigated by analyzing the aftershocks recorded by 13 stations installed around the fault in the period September 2010 - January 2011. Near-parallel fast directions were observed for split shear waves at several stations close to the fault zone, interpreting the effect as related to aligned fault fabric. In order to assess whether the anisotropy of rock properties could also affect ground motion polarization, we compute the wavefield polarization in the horizontal plane using about 40 seismic events among those recorded during the deployment. We apply an approach based on the computation of horizontal-to-vertical spectral ratios (HVSRs) and the diagonalization of the covariance matrix. The distribution of instantaneous polarization angles computed throughout the seismograms consists of narrow rose diagrams with low standard deviation at stations in the fault zone, where predominant horizontal polarization varies from N78° to N122°. In contrast, stations outside the fault zone show very scattered rose diagrams with no preferential orientation. We compare the horizontal polarization directions with fast directions. We find a near-orthogonal relation for stations in the fault zone. The same relationship between polarization and anisotropy was found in previous studies in the Parkfield area and in the Val d'Agri Basin, where polarization also forms a high-angle with the main fracture fields. The same cause of shear wave splitting is therefore also responsible for a stiffness anisotropy that produces more efficient propagation of ground motions polarized orthogonally to the fault fabric.

  10. Magnitude-dependent epidemic-type aftershock sequences model for earthquakes

    NASA Astrophysics Data System (ADS)

    Spassiani, Ilaria; Sebastiani, Giovanni

    2016-04-01

    We propose a version of the pure temporal epidemic type aftershock sequences (ETAS) model: the ETAS model with correlated magnitudes. As for the standard case, we assume the Gutenberg-Richter law to be the probability density for the magnitudes of the background events. Instead, the magnitude of the triggered shocks is assumed to be probabilistically dependent on that of the relative mother events. This probabilistic dependence is motivated by some recent works in the literature and by the results of a statistical analysis made on some seismic catalogs [Spassiani and Sebastiani, J. Geophys. Res. 121, 903 (2016), 10.1002/2015JB012398]. On the basis of the experimental evidences obtained in the latter paper for the real catalogs, we theoretically derive the probability density function for the magnitudes of the triggered shocks proposed in Spassiani and Sebastiani and there used for the analysis of two simulated catalogs. To this aim, we impose a fundamental condition: averaging over all the magnitudes of the mother events, we must obtain again the Gutenberg-Richter law. This ensures the validity of this law at any event's generation when ignoring past seismicity. The ETAS model with correlated magnitudes is then theoretically analyzed here. In particular, we use the tool of the probability generating function and the Palm theory, in order to derive an approximation of the probability of zero events in a small time interval and to interpret the results in terms of the interevent time between consecutive shocks, the latter being a very useful random variable in the assessment of seismic hazard.

  11. Propagation of Coulomb stress uncertainties in physics-based aftershock models

    NASA Astrophysics Data System (ADS)

    Cattania, Camilla; Hainzl, Sebastian; Wang, Lifeng; Roth, Frank; Enescu, Bogdan

    2014-10-01

    Stress transfer between earthquakes is recognized as a fundamental mechanism governing aftershock sequences. A common approach to relate stress changes to seismicity rate changes is the rate-and-state constitutive law developed by Dieterich: these elements are the foundation of Coulomb-rate-and-state (CRS) models. Despite the successes of Coulomb hypothesis and of the rate-and-state formulation, such models perform worse than statistical models in an operational forecasting context: one reason is that Coulomb stress is subject to large uncertainties and intrinsic spatial heterogeneity. In this study, we characterize the uncertainties in Coulomb stress inherited from different physical quantities and assess their effect on CRS models. We use a Monte Carlo method and focus on the following aspects: the existence of multiple receiver faults; the stress heterogeneity within grid cells, due to their finite size; and errors inherited from the coseismic slip model. We study two well-recorded sequences from different tectonic settings: the Mw = 6.0 Parkfield and the Mw= 9.0 Tohoku earthquakes. We find that the existence of multiple receiver faults is the most important source of intrinsic stress heterogeneity, and CRS models perform significantly better when this variability is taken into account. The choice of slip model also generates large uncertainties. We construct an ensemble model based on published slip models and find that it outperforms individual models. Our findings highlight the importance of identifying sources of errors and quantifying confidence boundaries in the forecasts; moreover, we demonstrate that consideration of stress heterogeneity and epistemic uncertainty has the potential to improve the performance of operational forecasting models.

  12. Aftershock asymmetry/rupture directivity among central San Andreas fault microearthquakes

    NASA Astrophysics Data System (ADS)

    Rubin, Allan M.; Gillard, Dominique

    2000-08-01

    Using a waveform cross-correlation technique, we have obtained precise relative locations for nearly 75% of the Northern California Seismic Network catalog (4300 earthquakes) occurring between 1984 and 1997 along 50 km of the San Andreas fault. Errors in relative location are meters to tens of meters for events separated by tens to hundreds of meters. We find that consecutive earthquakes in the relocated catalog occur no closer than a distance approximately equal to the radius of the first rupture, as estimated from the moment-magnitude relationship of Abercrombie [1996] assuming a 10-MPa stress drop. When the relative position vectors between consecutive events are normalized by this distance and projected onto the fault surface, they define a hole whose shape suggests that typical microearthquakes are elongate in the mode II (slip-parallel) direction by several tens of percent. Moreover, of the 100 immediate aftershocks occurring closest to the mode II edges of the prior rupture, more than twice as many occur to the northwest than to the southeast. We interpret this asymmetry as resulting from the large contrast in material properties across the fault. Models of dynamic rupture between dissimilar media predict that ruptures in this region may run preferentially to the southeast, in the direction of motion of the lower-velocity material. If so, then the barriers that stop rupture fronts moving to the southeast should initially be farther from failure, on average, than the barriers that stop rupture fronts moving to the northwest. Once the rupture stops, the induced stress change is more symmetric but the fault remains farther from failure (on average) to the southeast. This interpretation receives some support from pulse width measurements on a localized set of 72 magnitude 0.6 to 3.6 earthquakes.

  13. Aftershock Recordings of Nenana Mt. and Denali Fault Earthquakes of 2002

    NASA Astrophysics Data System (ADS)

    Estes, S. A.; Stachnik, J.; Hansen, R. A.

    2003-12-01

    Recent large earthquakes (M6.7, M7.9) in central Alaska ruptured the Denali Fault in late 2002. This rare opportunity to study this complex fault system required a substantial effort to obtain quality seismic data through the installation of a temporary seismic network. Less than one month after the M7.9 earthquake on November 3, 2002 twenty-six temporary sites were installed within 100 km of the Denali Fault. Of these 26 stations, 12 were Guralp 5-TD strong motion accelerometers recording triggered signals based on site-specific STA/LTA parameters to flash memory. The remaining 14 sites contained broadband seismometers (Guralp 40T or Guralp 3T) recording continuously to Reftek 72A-08 digital acquisition systems with 16- or 24-bit digitization and stored on Reftek 72A-05 hard drives. Stations were visited about every three weeks and remained in operation until the end of June 2003. The success of data recovery was inhibited by faulty power systems and inoperative equipment in harsh, remote Alaskan conditions. Installation and maintenance of this temporary network was performed by Alaska Earthquake Information Center (AEIC) personnel, with equipment provided by AEIC, PASSCAL, and the USGS. Data collected from the Denali Fault temporary network proved indispensable for the location of over 16,000 aftershocks between October 23 and the end of November 2002. Subsequently, we expanded the permanent broadband array along the Denali Fault westward of the 2002 rupture zone. In addition, one of the temporary sites (HARP) has become permanent. Data from this expanded network is recorded in real-time.

  14. Magnitude-dependent epidemic-type aftershock sequences model for earthquakes.

    PubMed

    Spassiani, Ilaria; Sebastiani, Giovanni

    2016-04-01

    We propose a version of the pure temporal epidemic type aftershock sequences (ETAS) model: the ETAS model with correlated magnitudes. As for the standard case, we assume the Gutenberg-Richter law to be the probability density for the magnitudes of the background events. Instead, the magnitude of the triggered shocks is assumed to be probabilistically dependent on that of the relative mother events. This probabilistic dependence is motivated by some recent works in the literature and by the results of a statistical analysis made on some seismic catalogs [Spassiani and Sebastiani, J. Geophys. Res. 121, 903 (2016)10.1002/2015JB012398]. On the basis of the experimental evidences obtained in the latter paper for the real catalogs, we theoretically derive the probability density function for the magnitudes of the triggered shocks proposed in Spassiani and Sebastiani and there used for the analysis of two simulated catalogs. To this aim, we impose a fundamental condition: averaging over all the magnitudes of the mother events, we must obtain again the Gutenberg-Richter law. This ensures the validity of this law at any event's generation when ignoring past seismicity. The ETAS model with correlated magnitudes is then theoretically analyzed here. In particular, we use the tool of the probability generating function and the Palm theory, in order to derive an approximation of the probability of zero events in a small time interval and to interpret the results in terms of the interevent time between consecutive shocks, the latter being a very useful random variable in the assessment of seismic hazard.

  15. T-wave characteristics of a large dataset of Sumatra aftershocks

    NASA Astrophysics Data System (ADS)

    Okal, E.

    2009-12-01

    We examine a dataset of T phases recorded at the seismic station` on Diego Garcia from 217 aftershocks of the 2004 Sumatra earthquake, for which CMT solutions are available. Each record is analyzed through its T-Phase Energy Flux and parameter gamma, expressing the ratio of TPEF to seismic moment, as defined by Okal et al. [2003]; and its duration-amplitude discriminant D, as defined by Talandier and Okal [2001]. In addition, the slowness parameter THETA [Newman and Okal, 1998] is computed from worldwide datasets of short-period P waves for all events. While there is no direct correlation between gamma and THETA, we find an increasing maximum gamma for any given THETA, meaning that slow events cannot give rise to large T waves. The extreme northern part of the rupture area (North of 11 deg.N) generally features reduced TPEF, which may express unfavorable source conversion properties. With this exception, we find no correlation of gamma with epicentral location, focal mechanism, or time elapsed since the main shock. Nor can we identify any obvious influence of depth on gamma, bearing in mind that the computation of TPEF is performed in the 2-10 Hz range. Similarly, values of the discriminant D are scattered geographically, with focal mechanism and depth. Furthermore, there is no evident correlation between D and gamma, The main shock itself features relatively low, but not minimal, values of both gamma and D, which is in line with its character of slowness which was previously reported (e.g., from source tomography and normal mode studies). The absence of direct correlations between the various parameters measured probably expresses a profound heterogeneity at the level of the individual faults activated in the wake of the Sumatra event, particularly for those outside the fault plane, which were triggered by stress transfer.

  16. Magnitude-dependent epidemic-type aftershock sequences model for earthquakes.

    PubMed

    Spassiani, Ilaria; Sebastiani, Giovanni

    2016-04-01

    We propose a version of the pure temporal epidemic type aftershock sequences (ETAS) model: the ETAS model with correlated magnitudes. As for the standard case, we assume the Gutenberg-Richter law to be the probability density for the magnitudes of the background events. Instead, the magnitude of the triggered shocks is assumed to be probabilistically dependent on that of the relative mother events. This probabilistic dependence is motivated by some recent works in the literature and by the results of a statistical analysis made on some seismic catalogs [Spassiani and Sebastiani, J. Geophys. Res. 121, 903 (2016)10.1002/2015JB012398]. On the basis of the experimental evidences obtained in the latter paper for the real catalogs, we theoretically derive the probability density function for the magnitudes of the triggered shocks proposed in Spassiani and Sebastiani and there used for the analysis of two simulated catalogs. To this aim, we impose a fundamental condition: averaging over all the magnitudes of the mother events, we must obtain again the Gutenberg-Richter law. This ensures the validity of this law at any event's generation when ignoring past seismicity. The ETAS model with correlated magnitudes is then theoretically analyzed here. In particular, we use the tool of the probability generating function and the Palm theory, in order to derive an approximation of the probability of zero events in a small time interval and to interpret the results in terms of the interevent time between consecutive shocks, the latter being a very useful random variable in the assessment of seismic hazard. PMID:27176281

  17. Sequence-based Parameter Estimation for an Epidemiological Temporal Aftershock Forecasting Model using Markov Chain Monte Carlo Simulation

    NASA Astrophysics Data System (ADS)

    Jalayer, Fatemeh; Ebrahimian, Hossein

    2014-05-01

    Introduction The first few days elapsed after the occurrence of a strong earthquake and in the presence of an ongoing aftershock sequence are quite critical for emergency decision-making purposes. Epidemic Type Aftershock Sequence (ETAS) models are used frequently for forecasting the spatio-temporal evolution of seismicity in the short-term (Ogata, 1988). The ETAS models are epidemic stochastic point process models in which every earthquake is a potential triggering event for subsequent earthquakes. The ETAS model parameters are usually calibrated a priori and based on a set of events that do not belong to the on-going seismic sequence (Marzocchi and Lombardi 2009). However, adaptive model parameter estimation, based on the events in the on-going sequence, may have several advantages such as, tuning the model to the specific sequence characteristics, and capturing possible variations in time of the model parameters. Simulation-based methods can be employed in order to provide a robust estimate for the spatio-temporal seismicity forecasts in a prescribed forecasting time interval (i.e., a day) within a post-main shock environment. This robust estimate takes into account the uncertainty in the model parameters expressed as the posterior joint probability distribution for the model parameters conditioned on the events that have already occurred (i.e., before the beginning of the forecasting interval) in the on-going seismic sequence. The Markov Chain Monte Carlo simulation scheme is used herein in order to sample directly from the posterior probability distribution for ETAS model parameters. Moreover, the sequence of events that is going to occur during the forecasting interval (and hence affecting the seismicity in an epidemic type model like ETAS) is also generated through a stochastic procedure. The procedure leads to two spatio-temporal outcomes: (1) the probability distribution for the forecasted number of events, and (2) the uncertainty in estimating the

  18. Should Coulomb stress change calculations be used to forecast aftershocks and to influence earthquake probability estimates? (Invited)

    NASA Astrophysics Data System (ADS)

    Parsons, T.

    2009-12-01

    After a large earthquake, our concern immediately moves to the likelihood that another large shock could be triggered, threatening an already weakened building stock. A key question is whether it is best to map out Coulomb stress change calculations shortly after mainshocks to potentially highlight the most likely aftershock locations, or whether it is more prudent to wait until the best information is available. It has been shown repeatedly that spatial aftershock patterns can be matched with Coulomb stress change calculations a year or more after mainshocks. However, with the onset of rapid source slip model determinations, the method has produced encouraging results like the M=8.7 earthquake that was forecast using stress change calculations from 2004 great Sumatra earthquake by McCloskey et al. [2005]. Here, I look back at two additional prospective calculations published shortly after the 2005 M=7.6 Kashmir and 2008 M=8.0 Wenchuan earthquakes. With the benefit of 1.5-4 years of additional seismicity, it is possible to assess the performance of rapid Coulomb stress change calculations. In the second part of the talk, within the context of the ongoing Working Group on California Earthquake Probabilities (WGCEP) assessments, uncertainties associated with time-dependent probability calculations are convolved with uncertainties inherent to Coulomb stress change calculations to assess the strength of signal necessary for a physics-based calculation to merit consideration into a formal earthquake forecast. Conclusions are as follows: (1) subsequent aftershock occurrence shows that prospective static stress change calculations both for Kashmir and Wenchuan examples failed to adequately predict the spatial post-mainshock earthquake distributions. (2) For a San Andreas fault example with relatively well-understood recurrence, a static stress change on the order of 30 to 40 times the annual stressing rate would be required to cause a significant (90%) perturbation to the

  19. Shear Wave Splitting Intensity of the Maule, Chile Rupture Zone: Results from Teleseismic and Local Aftershock Datasets

    NASA Astrophysics Data System (ADS)

    Torpey, M. E.; Russo, R. M.; Chevrot, S.

    2015-12-01

    We calculated the shear wave splitting intensity (SI) of the Maule, Chile rupture zone (32°S-39°S) to constrain the seismic anisotropy of the region. Our data are from 80 of the temporary seismometers deployed as part of the IMAD (International Maule Aftershock Deployment) geophysical networks to capture the aftershocks of the Mw 8.8 megathrust event in 2010. We implemented the multichannel analysis method of Chevrot (2000) to measure the SI of 64 teleseismic SKS phases in addition to the fast orientations ϕ and splitting delays δt measured with the method of Silver & Chan (1991). To measure the SI of local aftershocks, we modified the method to allow for use of the upgoing S phase from local events in and above the Nazca slab after correcting for the initial event polarization. We compared our results with other measurement methods (Silver and Chan 1991, Wolfe and Silver 1998) that solve for splitting parameters to examine the robustness of the shear wave splitting intensity method, particularly for local datasets. The results we obtained using the splitting intensity method for the teleseismic data show an overall fast direction that is parallel to the absolute plate motion of the Nazca plate that is subducting beneath the South American plate. These results are consistent with the results we calculated using the Wolfe and Silver method. SI deriving from S waves that originate in the Nazca slab or deeper SA lithosphere are likely to reveal patterns of crustal fabric, and hence differ from the SI of the teleseismic shear waves.

  20. Source parameters and effects of bandwidth and local geology on high- frequency ground motions observed for aftershocks of the northeastern Ohio earthquake of 31 January 1986

    USGS Publications Warehouse

    Glassmoyer, G.; Borcherdt, R.D.

    1990-01-01

    A 10-station array (GEOS) yielded recordings of exceptional bandwidth (400 sps) and resolution (up to 96 dB) for the aftershocks of the moderate (mb???4.9) earthquake that occurred on 31 January 1986 near Painesville, Ohio. Nine aftershocks were recorded with seismic moments ranging between 9 ?? 1016 and 3 ?? 1019 dyne-cm (MW: 0.6 to 2.3). The aftershock recordings at a site underlain by ???8m of lakeshore sediments show significant levels of high-frequency soil amplification of vertical motion at frequencies near 8, 20 and 70 Hz. Viscoelastic models for P and SV waves incident at the base of the sediments yield estimates of vertical P-wave response consistent with the observed high-frequency site resonances, but suggest additional detailed shear-wave logs are needed to account for observed S-wave response. -from Authors

  1. On the relationship between lower magnitude thresholds and bias in epidemic-type aftershock sequence parameter estimates

    NASA Astrophysics Data System (ADS)

    Schoenberg, Frederic Paik; Chu, Annie; Veen, Alejandro

    2010-04-01

    Modern earthquake catalogs are often described using spatial-temporal point process models such as the epidemic-type aftershock sequence (ETAS) models of Ogata (1998). Earthquake catalogs often have issues of incompleteness and other inaccuracies for earthquakes of magnitude below a certain threshold, and such earthquakes are typically removed prior to fitting a point process model. This paper investigates the bias in the parameters in ETAS models introduced by the removal of the smallest events. It is shown that in the case of most of the ETAS parameters, the bias increases approximately exponentially as a function of the lower magnitude cutoff.

  2. RETAS Stochastic Model to Study Aftershock Rate Decay of the Denali Fault M7.9 Earthquake, November 3, 2002

    SciTech Connect

    Gospodinov, D. K.; Marekova, E. G.; Marinov, A. T.

    2007-04-23

    A RETAS model is used to analyze aftershock rate decay after the Denaly Fault earthquake with a main shock magnitude MS=7.9. We verify different variants of the RETAS model ranging from the limit case Mth = Mmain (main shock) to the case when Mth=Mo (lower magnitude cut-off). We first test the model on simulated data following the MOF (modified Omori formula) model. The results for the Denali Fault sequence reveal the best fit model to be RETAS with a triggering threshold Mth =3.2.

  3. Rupture Characteristics and Aftershocks of the July 15, 2003 Carlsberg `H' (Indian Ocean) Mw 7.6 Earthquake

    NASA Astrophysics Data System (ADS)

    Antolik, M.; Abercrombie, R. E.; Pan, J.; Ekstrom, G.

    2003-12-01

    The occurrence of a Mw 7.6 earthquake near the Carlsberg ridge (15 July, 2003) provides valuable information about earthquake rupture processes in oceanic lithosphere, which are not well understood, and the distributed deformation of the India-Australia plate. The earthquake had a strike-slip mechanism opposite to that of the transform faults on the ridge, and appears to have ruptured a fracture zone (designated as `H' by Royer et al., 1997) within the India-Australia composite plate. We examine the rupture characteristics of this earthquake using the full spectrum of seismic radiation. Inversion of the body waves indicates rapid rupture propagation toward the NE, away from the Carlsberg Ridge, for a distance of ˜200 km. The average rupture velocity is well constrained and is ˜3.6 km s-1. The total source duration is ˜60 s; however, nearly all of the moment release occurs in the last 30 s. The age of the lithosphere in the area of largest moment is release is 10-15 Ma. The body waves can be well fit with a simple rupture model and no jump of fracture zones is required, as has been suggested for some oceanic earthquakes (e.g., McGuire et al., 1996). The source process is very similar to the well-studied 1994 Mw 7.0 earthquake along the Romanche transform in the equatorial Atlantic (Abercrombie and Ekström, 2001). We also analyze the aftershock distribution using multiple-hypocenter relocation techniques and moment-tensor analysis using intermediate-period surface waves. Only 15 aftershocks (M > 4.5) are listed in the USGS catalog, which is typical of large oceanic earthquakes (e.g., Boettcher and Jordan, 2001). Moment tensors obtained from five of the aftershocks show a diversity of focal mechanisms. We interpret a cluster of aftershocks located at ˜1o S as representing extension which results from the stress field of the mainshock at the end of the rupture. This interpretation is consistent with the 200-km rupture length inferred from body waves. The focal

  4. Using aftershocks to Image the Subducting Pacific Plate in a Region of Deep Slow Slip, Hikurangi Margin, New Zealand

    NASA Astrophysics Data System (ADS)

    Jacobs, K. M.; Hirschberg, H.; Louie, J. N.; Savage, M. K.; Bannister, S. C.

    2014-12-01

    We present seismic migrations using aftershocks of two M>6 earthquakes as sources. The Southern Cook Strait earthquake sequence, beginning on 19 July 2013, included the 21 July M=6.5 and 16 August M=6.6 2013 earthquakes, which were the largest shallow earthquakes to strike the Wellington region since 1942. Following the two largest earthquakes we began the Seddon Earthquake Aftershock Structural Investigation (SEASI) and deployed a line of 21 seismometers stretching approximately 400 km along the strike of the Hikurangi subduction zone in order to use aftershocks to illuminate the structure of the subducted Pacific slab. The SEASI line ties into the SAHKE line, which was an array of up to 900 seismometers that recorded air gun and explosion shots in deployments from 2009-2011. The SAHKE project characterized the structures perpendicular to the strike of the subduction zone. Our results use the SAHKE line as a starting point and look for strike-parallel variations in the depth of the Moho and other structures. Previous studies have suggested potential changes along strike in this region, and deep slow slip events (> 35 km) are also observed north of Wellington, further indicating that variation in properties exists along slab strike. We have used 246 M > 3 earthquakes that occurred from September 2013 through January 2014 to create common receiver gathers. Multicomponent prestack depth migration of these receiver gathers, with operator antialiasing control and prestack coherency filtering, produces reflectivity sections using a 1-D velocity model derived from the SAHKE project. Relocation of aftershocks of the Seddon earthquakes using the deployment of a temporary array by New Zealand GeoNet facilitates the migration. An initial P-P migration shows a north-dipping reflector at 15-25 km depth under the earthquake sequence, and suggests the Moho at 20-25 km depth. From Wellington, a reflector dips very gently south from 25-35 km depth, which is probably the slab

  5. Fault Simulator with Dilatant Effects Used to Investigate Statistics of Foreshocks/Aftershocks, Including Magnitude Dependent Seismic Quiescence

    NASA Astrophysics Data System (ADS)

    Smith, D. E.; Sacks, S. I.; Rydelek, P. A.

    2011-12-01

    We add dilatant effects to a fault simulator to include physics consistent with observations of seismic quiescence. Using this simulator, we examine precursory and aftershock statistics of major events, changes in b-value, correlations between slip and static stress changes, changes in the in-plane focal mechanisms, and temporal decay of aftershocks. Seismic quiescence has been observed for a number major events including, 1982 Urakawa-Oki earthquake [Taylor et al., 1992], 1994 Hokkaido-Toho-Oki earthquake [Takanami et al., 1996], 1994 Northridge earthquake [Smith and Sacks, 2011], 1995 Kobe earthquake [Enescu et al., 2011], 1988 Spitak earthquake [Wysse and Martirosyan, 1998], and 2011 Tohoku earthquake [Katsumata, in press, 2011]. The physics of dilatancy theory [Nur, 1972; Whitcomb et al., 1973; Scholz et al., 1973], which we include in the simulator, is proposed as an explanation for seismic quiescence [Takanami et al., 1996; Scholz, 2000]. As the fault is loaded toward failure and the stress increases, if the stress is sufficiently high, the rock can begin to dilate. As dilation causes an increase in the rock volume, the pore pressure decreases, the effective normal stress increases, and the fault core strengthens [Rice, 1975]. Because the fault core supports more of the stress, the seismicity of the surrounding region will decrease as is observed. Over time (~2-20 years) the water will percolate back into the fault core from the surrounding region. The pore pressure in the fault core increases again, the normal stress decreases, and failure is encouraged. This dilatant effect on the fault core foreshocks, surrounding quiescence zone, and the aftershocks, can be studied by modifying the fault simulator of Sacks and Rydelek [1995]; Rydelek and Sacks [1996]. Based on simple physics: discrete patches, Coulomb failure, and redistribution of stresses on a specified fault geometry, this simulator (without dilatancy) has already been shown to reproduce Gutenberg

  6. Performance measurement of mobile manipulators

    NASA Astrophysics Data System (ADS)

    Bostelman, Roger; Hong, Tsai; Marvel, Jeremy

    2015-05-01

    This paper describes a concept for measuring the reproducible performance of mobile manipulators to be used for assembly or other similar tasks. An automatic guided vehicle with an onboard robot arm was programmed to repeatedly move to and stop at a novel, reconfigurable mobile manipulator artifact (RMMA), sense the RMMA, and detect targets on the RMMA. The manipulator moved a laser retroreflective sensor to detect small reflectors that can be reconfigured to measure various manipulator positions and orientations (poses). This paper describes calibration of a multi-camera, motion capture system using a 6 degree-of-freedom metrology bar and then using the camera system as a ground truth measurement device for validation of the reproducible mobile manipulator's experiments and test method. Static performance measurement of a mobile manipulator using the RMMA has proved useful for relatively high tolerance pose estimation and other metrics that support standard test method development for indexed and dynamic mobile manipulator applications.

  7. Geophysical data reveal the crustal structure of the Alaska Range orogen within the aftershock zone of the Mw 7.9 Denali fault earthquake

    USGS Publications Warehouse

    Fisher, M.A.; Ratchkovski, N.A.; Nokleberg, W.J.; Pellerin, L.; Glen, J.M.G.

    2004-01-01

    Geophysical information, including deep-crustal seismic reflection, magnetotelluric (MT), gravity, and magnetic data, cross the aftershock zone of the 3 November 2002 Mw 7.9 Denali fault earthquake. These data and aftershock seismicity, jointly interpreted, reveal the crustal structure of the right-lateral-slip Denali fault and the eastern Alaska Range orogen, as well as the relationship between this structure and seismicity. North of the Denali fault, strong seismic reflections from within the Alaska Range orogen show features that dip as steeply as 25?? north and extend downward to depths between 20 and 25 km. These reflections reveal crustal structures, probably ductile shear zones, that most likely formed during the Late Cretaceous, but these structures appear to be inactive, having produced little seismicity during the past 20 years. Furthermore, seismic reflections mainly dip north, whereas alignments in aftershock hypocenters dip south. The Denali fault is nonreflective, but modeling of MT, gravity, and magnetic data suggests that the Denali fault dips steeply to vertically. However, in an alternative structural model, the Denali fault is defined by one of the reflection bands that dips to the north and flattens into the middle crust of the Alaska Range orogen. Modeling of MT data indicates a rock body, having low electrical resistivity (>10 ??-m), that lies mainly at depths greater than 10 km, directly beneath aftershocks of the Denali fault earthquake. The maximum depth of aftershocks along the Denali fault is 10 km. This shallow depth may arise from a higher-than-normal geothermal gradient. Alternatively, the low electrical resistivity of deep rocks along the Denali fault may be associated with fluids that have weakened the lower crust and helped determine the depth extent of the after-shock zone.

  8. Preparation phase and consequences of a large earthquake: insights from foreshocks and aftershocks of the 2014 Mw 8.1 Iquique earthquake, Chile

    NASA Astrophysics Data System (ADS)

    Cesca, Simone; Grigoli, Francesco; Heimann, Sebastian; Dahm, Torsten

    2015-04-01

    The April 1, 2014, Mw 8.1 Iquique earthquake in Northern Chile, was preceded by an anomalous, extensive preparation phase. The precursor seismicity at the ruptured slab segment was observed sporadically several months before the main shock, with a significant increment in seismicity rates and observed magnitudes in the last three weeks before the main shock. The large dataset of regional recordings helped us to investigate the role of such precursor activity, comparing foreshock and aftershock seismicity to test models of rupture preparation and models of strain and stress rotation during an earthquake. We used full waveforms techniques to locate events, map the seismicity rate, derive source parameters, and assess spatiotemporal stress changes. Results indicate that the spatial distributions of foreshocks delineated the shallower part of the rupture areas of the main shock and its largest aftershock, and is well matching the spatial extension of the aftershocks. During the foreshock sequence, seismicity spatially is mainly localized in two clusters, separated by a region of high locking. The ruptures of mainshock and largest aftershock nucleate within these clusters and propagate to the locked region; the aftershocks are again localized in correspondence to the original spatial clusters, and the central region is locked again. More than 300 moment tensor inversions were performed, down to Mw 4.0, most of them corresponding to almost pure double couple thrust mechanisms, with a geometry consistent with the slab orientation. No significant differences are observed among thrust mechanisms in different areas, nor among thrust foreshocks and aftershocks. However, a new family of normal fault mechanisms appears after the main shock, likely affecting the shallow wedge structure in consequence of the increased extensional stress in this region. We infer a stress rotation after the main shock, as proposed for recent larger thrust earthquakes, which suggests that the April

  9. Stress shadows of the 2011 Mw=9.0 Tohoku-oki, Japan, earthquake: Suppressed aftershocks of the 2008 Mw=6.6 Iwate-Miyagi inland earthquake

    NASA Astrophysics Data System (ADS)

    Suzuki, Y.; Toda, S.

    2013-12-01

    Numerous papers of stress triggering have been published since 1990s. Among them, only a few studies have evidently shown that seismicity shut down or suppression associated with static Coulomb stress decrease (hereinafter 'stress shadow'). The reason only fewer reports exist is its restrictive conditions to detect stress shadow. To prove statistical significance, the following conditions are satisfied: (i) high seismicity rate before a disturbance, (ii) long elapsed time required since the disturbance, (iii) negative Coulomb stress on most of the pre-existing faults in the area. A preceding aftershocks before the disturbance is often used to satisfy the condition (i) (e.g. Toda and Stein, 2003). But one must strictly consider a temporal decay of aftershocks to fairly compare the post-disturbance rate with the pre-disturbance rate. To calibrate such potential bias, we employ the Epidemic-Type Aftershock Sequence (ETAS) model (Ogata, 1988) which can simulate the temporal decay and effect of secondary aftershocks. Here, we use the Japan Meteorological Agency (JMA) earthquake catalog from 2000 to June 2013 (depth≤25km) and examine any deviation of observed rate from theoretical seismicity predicted by the ETAS model after the 2011 Tohoku-oki earthquake. We here focus on aftershock areas of the 2008 Iwate-Miyagi inland earthquake (Mw 6.6), the 2003 North-Miyagi earthquake (Mw 6.0) and the 2010 Fukushima earthquake (Mw 5.5), all of which are mostly supposed to satisfy all the conditions. To detect seismicity rate change between before and after a stress perturbation, one must estimate the minimum magnitude of completeness (Mc) throughout the testing period. Based on a report of JMA (2012) and our own magnitude-frequency plots, we set Mc=3.0 in the Iwate-Miyagi inland earthquake and the North-Miyagi earthquake, and Mc=2.0 in the Fukushima earthquake regions. To rigorously define their aftershock zones, we calculate seismicity rate before (Rb) and after (Ra) their own

  10. The Mw 5.8 Mineral, Virginia, earthquake of August 2011 and aftershock sequence: constraints on earthquake source parameters and fault geometry

    USGS Publications Warehouse

    McNamara, Daniel E.; Benz, H.M.; Herrmann, Robert B.; Bergman, Eric A.; Earle, Paul; Meltzer, Anne; Withers, Mitch; Chapman, Martin

    2014-01-01

    The Mw 5.8 earthquake of 23 August 2011 (17:51:04 UTC) (moment, M0 5.7×1017  N·m) occurred near Mineral, Virginia, within the central Virginia seismic zone and was felt by more people than any other earthquake in United States history. The U.S. Geological Survey (USGS) received 148,638 felt reports from 31 states and 4 Canadian provinces. The USGS PAGER system estimates as many as 120,000 people were exposed to shaking intensity levels of IV and greater, with approximately 10,000 exposed to shaking as high as intensity VIII. Both regional and teleseismic moment tensor solutions characterize the earthquake as a northeast‐striking reverse fault that nucleated at a depth of approximately 7±2  km. The distribution of reported macroseismic intensities is roughly ten times the area of a similarly sized earthquake in the western United States (Horton and Williams, 2012). Near‐source and far‐field damage reports, which extend as far away as Washington, D.C., (135 km away) and Baltimore, Maryland, (200 km away) are consistent with an earthquake of this size and depth in the eastern United States (EUS). Within the first few days following the earthquake, several government and academic institutions installed 36 portable seismograph stations in the epicentral region, making this among the best‐recorded aftershock sequences in the EUS. Based on modeling of these data, we provide a detailed description of the source parameters of the mainshock and analysis of the subsequent aftershock sequence for defining the fault geometry, area of rupture, and observations of the aftershock sequence magnitude–frequency and temporal distribution. The observed slope of the magnitude–frequency curve or b‐value for the aftershock sequence is consistent with previous EUS studies (b=0.75), suggesting that most of the accumulated strain was released by the mainshock. The aftershocks define a rupture that extends between approximately 2–8 km in depth and 8–10 km along

  11. A preliminary study of the Santa Barbara, California, earthquake of August 13, 1978, and its major aftershocks

    USGS Publications Warehouse

    Lee, William Hung Kan; Johnson, C.E.; Henyey, T.L.; Yerkes, R.L.

    1978-01-01

    The ML5.1 Santa Barbara earthquake of August 13, 1978 occurred at lat 34 ? 22.2'N., long 119 ? 43.0' 4 km south of Santa Barbara, Calif. at a depth of 12.5 km in the northeast Santa Barbara Channel, part of the western Transverse Ranges geomorphic-structural province. This part of the province is characterized by seismically active, east-trending reverse faults and rates of coastal uplift that have averaged up to about 10 m/1000 years over the last 45,000 years. No surface rupture was detected onshore. Subsurface rupture propagated northwest from the main shock toward Goleta, 15 km west of Santa Barbara, where a maximum acceleration of 0.44 g was measured at ground level and extensive minor damage occurred; only minor injuries were reported. A fairly well-constrained fault-plane solution of the main shock and distribution of the aftershocks indicate that left-reverse-oblique slip occurred on west-northwest-trending, north-dipping reverse faults; inadequate dip control precludes good correlation with any one of several mapped faults. Had the earthquake been larger and rupture propagated to the southeast or a greater distance to the northwest, it could have posed a hazard to oilfield operations. The fault-plane solution and aftershock pattern closely fit the model of regional deformation and the solution closely resembles those of five previously mapped events located within a 15-km radius.

  12. Aftershocks Prediction In Italy: Estimation of Time-magnitude Distribution Model Parameters and Computation of Probabilities of Occurrence.

    NASA Astrophysics Data System (ADS)

    Lolli, B.; Gasperini, P.

    We analyzed the available instrumental catalogs of Italian earthquakes from 1960 to 1996 to compute the parameters of the time-magnitude distribution model proposed by Reasenberg e Jones (1989, 1994) and currently used to make aftershock predictions in California. We found that empirical corrections ranging from 0.3 (before 1976) to 0.5 magnitude units (between 1976 and 1980) are necessary to make the dataset ho- mogeneous over the entire period. The estimated model parameters result quite stable with respect to mainshock magnitude and sequence detection algorithm, while their spatial variations suggest that regional estimates might predict the behavior of future sequences better than ones computed by the whole Italian dataset. In order to improve the goodness of fit for sequences including multiple mainshocks (like the one occurred in Central Italy from September 1997 to May 1998) we developed a quasi epidemic model (QETAS) consisting of the superposition of a small number of Omori's pro- cesses originated by strong aftershocks. We found that the inclusion in the QETAS model of the shocks with magnitude larger than mainshock magnitude minus one (that are usually located and sized in near real-time by the observatories) improves significantly the ability of the algorithm to predict the sequence behaviors.

  13. Source Properties of Repeating Small Earthquakes in the Aftershock Zones of the 1999 Izmit and Duzce Earthquakes

    NASA Astrophysics Data System (ADS)

    Ben-Zion, Y.; Peng, Z.

    2006-12-01

    We estimate the source parameters of repeating small earthquakes in the aftershock zones of the 1999 Mw7.4 Izmit and Mw7.1 Duzce earthquakes. The analysis employs 36 sets of highly repeating earthquakes, ranging in size from M 0 to M 3.0, that occurred from August 1999 to February 2000 along the Karadere-Duzce segment of the north Anatolian fault [Peng and Ben-Zion, 2006]. A local PASSCAL network consisting of 10 short-period stations recorded the data. We compute spectra from each seismogram using a multitaper technique. We measure the difference between events by dividing the spectra of the each individual record to the average spectra at that station [Vidale et al., 1994]. Stable spectra ratios are obtained by stacking the ratios calculated from moving windows starting from the P waves to the S-coda waves [Imanishi and Ellsworth, 2006]. Next, we estimate the seismic potencies and corner frequencies for events in each cluster using a simple source model. The continuing work will focus on deriving static stress drops, apparent stresses and radiated energy of these repeating earthquakes. A comparison of the source properties of the repeating small earthquakes with those of large aftershocks and the Duzce main shock would allow us to examine whether there are systematic variations with location and/or size.

  14. Cumulative Coulomb Stress Triggering as an Explanation for the Canterbury (New Zealand) Aftershock Sequence: Initial Conditions Are Everything?

    NASA Astrophysics Data System (ADS)

    Bebbington, Mark; Harte, David; Williams, Charles

    2016-01-01

    Using 2 years of aftershock data and three fault-plane solutions for each of the initial M7.1 Darfield earthquake and the larger (M >6) aftershocks, we conduct a detailed examination of Coulomb stress transfer in the Canterbury 2010-2011 earthquake sequence. Moment tensor solutions exist for 283 of the events with M ≥ 3.6, while 713 other events of M ≥ 3.6 have only hypocentre and magnitude information available. We look at various methods for deciding between the two possible mechanisms for the 283 events with moment tensor solutions, including conformation to observed surface faulting, and maximum ΔCFF transfer from the Darfield main shock. For the remaining events, imputation methods for the mechanism including nearest-neighbour, kernel smoothing, and optimal plane methods are considered. Fault length, width, and depth are arrived at via a suite of scaling relations. A large (50-70 %) proportion of the faults considered were calculated to have initial loading in excess of the final stress drop. The majority of faults that accumulated positive ΔCFF during the sequence were `encouraged' by the main shock failure, but, on the other hand, of the faults that failed during the sequence, more than 50 % of faults appeared to have accumulated a negative ΔCFF from all preceding failures during the sequence. These results were qualitatively insensitive to any of the factors considered. We conclude that there is much unknown about how Coulomb stress triggering works in practice.

  15. Fractal structure and predictability of distances between consecutive events: an analysis of three seismic aftershock sequences in Southern California

    NASA Astrophysics Data System (ADS)

    Martinez, Maria-Dolors; Lana, Xavier; Monterrubio, Marisol; Serra, Carina

    2015-04-01

    Three series of distances between consecutive seismic events are analysed by means of mono- and multifractal techniques with the aim of quantifying the complexity of their physical mechanism and their predictability and predictive instability. These series are also simulated by means of fractional noise by taking into account their self-affine character, the dependence of their power spectra on frequency and the values of Hurst and Hausdorff exponents. The prediction of these series is also attempted by means of an autoregressive AR(p) process to estimate the p+1 distance depending on the previous p distances. The interevent distance series are derived from the aftershock sequences associated with Landers (Mw 7.3 June 28, 1992), Northridge (Mw 6.7 January 17, 1994) and Hector Mine (Mw 7.1 October 16, 1999) mainshocks. The seismic records are obtained from the Southern California Seismic Network (SCSN) catalogue. Aftershocks with Mw equalling to or exceeding 2.0 are considered in order to assure catalogue completeness.

  16. CHARACTERISTICS OF THE AFTERSHOCK SEQUENCE OF THE BORAH PEAK, IDAHO, EARTHQUAKE DETERMINED FROM DIGITAL RECORDINGS OF THE EVENTS.

    USGS Publications Warehouse

    Boatwright, John

    1985-01-01

    The U. S. Geological Survey, Menlo Park, deployed and maintained a network of twelve digital instruments over the 2 weeks following the October 28, 1983, Borah Peak, Idaho, earthquake. The network recorded 45 events with M greater than equivalent to 3. 0, and 6 events with M less than equivalent to 4. 0. The seismic moments of the aftershocks increase with increasing hypocentral depth below 12 km. The dynamic stress drops of the events do not show any systematic variation with depth, however. Most of the events with large stress drops are clustered in the northwest limb of the aftershock distribution; the average stress drop of the southern events is 31 plus or minus 16 bars, while the average stress drop of the events in the northwest limb is 77 plus or minus 52 bars. This clustering of events with large stress drops marks an apparent stress concentration, possibly associated with the arrest of the main shock rupture propagation by a fracture barrier at depth.

  17. The 1997 Umbria-Marche, Italy, Earthquake Sequence: A first look at the main shocks and aftershocks

    NASA Astrophysics Data System (ADS)

    Amato, A.; Azzara, R.; Chiarabba, C.; Cimini, G. B.; Cocco, M.; Di Bona, M.; Margheriti, L.; Mazza, S.; Mele, F.; Selvaggi, G.; Basili, A.; Boschi, E.; Courboulex, F.; Deschamps, A.; Gaffet, S.; Bittarelli, G.; Chiaraluce, L.; Piccinini, D.; Ripepe, M.

    A long sequence of earthquakes, six with magnitudes between 5 and 6, struck Central Italy starting on September 26, 1997, causing severe damages and loss of human lives. The seismogenic structure consists of a NW-SE elongated fault zone extending for about 40 km. The focal mechanisms of the largest shocks reveal normal faulting with NE-SW extension perpendicular to the trend of the Apennines, consistently with the Quaternary tectonic setting of the internal sector of the belt and with previous earthquakes in adjacent regions. Preliminary data on the main shocks and aftershocks show that extension in this region of the Apennines is accomplished by normal faults dipping at low angle (∼40°) to the southwest, and confined in the upper ∼8 km of the crust. These normal faults might have reactivated thrust planes of the Pliocene compressional tectonics. The aftershock distribution and the damage patterns also suggest that the three main shocks ruptured distinct 5 to 15 km-long fault segments, adjacent and slightly offset from one another.

  18. Site response for urban Los Angeles using aftershocks of the Northridge earthquake

    USGS Publications Warehouse

    Hartzell, S.; Leeds, A.; Frankel, A.; Michael, J.

    1996-01-01

    Ground-motion records from aftershocks of the 1994 Northridge earthquake are used to estimate site response in the urban Los Angeles area. Over 1300 shear-wave records from 61 sources and 90 sites are used in a linear inversion for source and site-response spectra. The methodology makes no assumptions about the shape of the source spectrum. To obtain a stable unique inverse, a Q model and geometrical spreading factor are assumed. In addition, the site response at a hardrock site is constrained to be approximately 1.0 with a kappa of 0.02. The site-response spectra compare favorably with the results of previous and on-going investigations in Los Angeles. A couple of first-order effects are lower site response in the surrounding mountains, dominated by Mesozoic and Tertiary rocks, and higher values in the San Fernando and Los Angeles Basins, containing surficial Pleistocene and Holocene alluvial deposits. Results show good correlation of high site-response spectral values with localized areas of severe damage (Interstate 10 collapse, Sherman Oaks, Northridge, Interstate 5/14 collapse). However, widespread trends in site response across the sedimentary basins are not obvious. The data suggest that site responses are lower near the southern margin of the San Fernando Valley for sources to the north, due to north-dipping sedimentary structures. But the general pattern of site response is characterized by high variability on length scales less than a kilometer. Variations of a factor of 2 in site response are observed over the length scale of 200 m and for the same surficial geologic unit. For some of the alluvial basin sites, surface-wave generation is a significant contributor to elevated site response at lower frequencies, below 2 Hz. The total damage pattern for the Northridge earthquake is influenced by strong source directivity to the north and strong local site effects. The correlation of weak-motion site-response estimates with areas of significant damage

  19. Shear Wave Splitting Analysis of Aftershocks of the 2013 Mw6.6 Lushan Earthquake, China

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Zhang, H.

    2013-12-01

    Shear wave splits into faster and slower shear waves that are nearly perpendicular when it travels through an anisotropic medium. There are two important parameters of shear wave splitting, one is the fast polarization direction of the fast shear wave and the other one is the time delay of the slow shear wave. The mechanisms for anisotropy in the upper crust can be divided into two categories. The first category is stress-induced anisotropy related to alignment of cracks in response to the in situ stress field. The second category is structural anisotropy associated with aligned planar features such as fault zone fabrics, sedimentary bedding planes and aligned minerals. We can characterize anisotropy around fault zone by shear wave splitting analysis. We used cross-correlation method for the shear wave splitting analysis. Since the faster shear wave and the slower shear wave are from the same source, they will correlate well after the time delay correction. We rotated two horizontal seismograms at a 10 increment of azimuth α from 00 to 1800. For each α, the cross-correlation coefficients between the two orthogonal seismograms are calculated for a range of time delays τ. When the absolute value of cross-correlation coefficient reaches a maximum, the corresponding values of α and τ are chosen as the fast polarization direction of the faster shear wave and the time delay of the slower shear wave, respectively. We chose 200 aftershocks observed at a temporary array consisting of 29 stations in the Lushan region. Shear wave arrivals were first picked for setting up the time window for the shear wave splitting analysis using the cross-correlation method. Because these 200 events are shallower than 20km, we can infer that the shear wave splitting is caused by crustal anisotropy. The rose diagram of the fast polarization directions of the fast shear waves showed two major directions. One is nearly parallel to the south-north trending fault system in this region, and

  20. April 25, 2015, Gorkha Earthquake, Nepal and Sequence of Aftershocks: Key Lessons

    NASA Astrophysics Data System (ADS)

    Guragain, R.; Dixit, A. M.; Shrestha, S. N.

    2015-12-01

    The Gorkha Earthquake of M7.8 hit Nepal on April 25, 2015 at 11:56 am local time. The epicenter of this earthquake was Barpak, Gorkha, 80 km northwest of Kathmandu Valley. The main shock was followed by hundreds of aftershocks including M6.6 and M6.7 within 48 hours and M7.3 on May 12, 2015. According to the Government of Nepal, a total of 8,686 people lost their lives, 16,808 people injured, over 500,000 buildings completely collapsed and more than 250,000 building partially damaged. The National Society for Earthquake Technology - Nepal (NSET), a not-for-profit civil society organization that has been focused on earthquake risk reduction in Nepal for past 21 years, conducted various activities to support people and the government in responding to the earthquake disaster. The activities included: i) assisting people and critical facility institutions to conduct rapid visual building damage assessment including the training; ii) information campaign to provide proper information regarding earthquake safety; iii) support rescue organizations on search and rescue operations; and iv) provide technical support to common people on repair, retrofit of damaged houses. NSET is also involved in carrying out studies related to earthquake damage, geotechnical problems, and causes of building damages. Additionally, NSET has done post-earthquake detail damage assessment of buildings throughout the affected areas. Prior to the earthquake, NSET has been working with several institutions to improve seismic performance of school buildings, private residential houses, and other critical structures. Such activities implemented during the past decade have shown the effectiveness of risk reduction. Retrofitted school buildings performed very well during the earthquake. Preparedness activities implemented at community levels have helped communities to respond immediately and save lives. Higher level of earthquake awareness achieved including safe behavior, better understanding of

  1. Typical Scenario of Preparation, Implementation, and Aftershock Sequence of a Large Earthquake

    NASA Astrophysics Data System (ADS)

    Rodkin, Mikhail

    2016-04-01

    We have tried here to construct and examine the typical scenario of a large earthquake occurrence. The Harvard seismic moment GCMT catalog was used to construct the large earthquake generalized space-time vicinity (LEGV) and to investigate the seismicity behavior in LEGV. LEGV was composed of earthquakes falling into the zone of influence of any of the considerable number (100, 300, or 1,000) of largest earthquakes. The LEGV construction is aimed to enlarge the available statistics, diminish a strong random component, and to reveal in result the typical features of pre- and post-shock seismic activity in more detail. In result of the LEGV construction the character of fore- and aftershock cascades was examined in more detail than it was possible without of the use of the LEGV approach. It was shown also that the mean earthquake magnitude tends to increase, and the b-values, mean mb/mw ratios, apparent stress values, and mean depth tend to decrease. Amplitudes of all these anomalies increase with an approach to a moment of the generalized large earthquake (GLE) as a logarithm of time interval from GLE occurrence. Most of the discussed anomalies agree well with a common scenario of development of instability. Besides of such precursors of common character, one earthquake-specific precursor was found. The revealed decrease of mean earthquake depth during large earthquake preparation testifies probably for the deep fluid involvement in the process. The revealed in LEGV typical features of development of shear instability agree well with results obtained in laboratory acoustic emission (AE) study. Majority of the revealed anomalies appear to have a secondary character and are connected mainly with an increase in a mean earthquake magnitude in LEGV. The mean magnitude increase was shown to be connected mainly with a decrease of a portion of moderate size events (Mw 5.0 - 5.5) in a closer GLE vicinity. We believe that this deficit of moderate size events hardly can be

  2. Mobile Customer Relationship Management and Mobile Security

    NASA Astrophysics Data System (ADS)

    Sanayei, Ali; Mirzaei, Abas

    The purpose of this study is twofold. First, in order to guarantee a coherent discussion about mobile customer relationship management (mCRM), this paper presents a conceptualization of mCRM delineating its unique characteristics because of Among the variety of mobile services, considerable attention has been devoted to mobile marketing and in particular to mobile customer relationship management services. Second, the authors discusses the security risks in mobile computing in different level(user, mobile device, wireless network,...) and finally we focus on enterprise mobile security and it's subgroups with a series of suggestion and solution for improve mobile computing security.

  3. A Transdisciplinary Training Program for Providing Seating Positioning and Mobility Intervention to Children with Developmental Disabilities Who Are 0-3 Years of Age.

    ERIC Educational Resources Information Center

    Sylvester, Lorrie; Shelden, M'Lisa

    The Oklahoma Assistive Technology Center was developed as an interagency collaborative effort, with one of its services being the delivery of positioning and mobility services to young children with developmental disabilities. The Center operates as an outpatient clinic and coordinates outreach services through two satellite centers in rural…

  4. Going mobile

    NASA Astrophysics Data System (ADS)

    Brus, Eric

    1987-12-01

    By 1990, all metropolitan areas in the U.S. and rural areas close to major cities or towns are expected to have cellular telephone service; 22 Canadian cities also feature cellular service. To supply mobile telecommunication services to sparsely-populated rural areas, a mobile satellite service (MSS) is now being developed. In this paper the projected possibilities of the MSS system are discussed, including a possibility that a piggyback-MSS payload be added to the GSTAR-4 satellite which is scheduled for a launch in 1988 or 1989; one in which some of the hardware from aborted direct-broadcast satellites would be used; and the possibility of building a new MSS satellite with large servicing capacity. Canada is planning to launch its own mobile satellite, MSAT, in the early 1990s. The MSS is expected to be 'generic', serving not only people on land but maritime and aeronautical users as well. It will also offer major benefits to truck and automobile drivers, making it possible for them to conduct business or to call for assistance from locations beyond the range of cellular systems.

  5. Mobile Autonomous Humanoid Assistant

    NASA Technical Reports Server (NTRS)

    Diftler, M. A.; Ambrose, R. O.; Tyree, K. S.; Goza, S. M.; Huber, E. L.

    2004-01-01

    A mobile autonomous humanoid robot is assisting human co-workers at the Johnson Space Center with tool handling tasks. This robot combines the upper body of the National Aeronautics and Space Administration (NASA)/Defense Advanced Research Projects Agency (DARPA) Robonaut system with a Segway(TradeMark) Robotic Mobility Platform yielding a dexterous, maneuverable humanoid perfect for aiding human co-workers in a range of environments. This system uses stereo vision to locate human team mates and tools and a navigation system that uses laser range and vision data to follow humans while avoiding obstacles. Tactile sensors provide information to grasping algorithms for efficient tool exchanges. The autonomous architecture utilizes these pre-programmed skills to form human assistant behaviors. The initial behavior demonstrates a robust capability to assist a human by acquiring a tool from a remotely located individual and then following the human in a cluttered environment with the tool for future use.

  6. Coulomb stress change for the normal-fault aftershocks triggered near the Japan Trench by the 2011 M w 9.0 Tohoku-Oki earthquake

    NASA Astrophysics Data System (ADS)

    Sato, Tamao; Hiratsuka, Shinya; Mori, Jim

    2012-12-01

    Coulomb stress triggering is examined using well-determined aftershock focal mechanisms and source models of the 2011 M w 9.0 off the Pacific coast of Tohoku Earthquake. We tested several slip distributions obtained by inverting onshore GPS-derived coseismic displacements under different a priori constraints on the initial fault parameters. The aftershock focal mechanisms are most consistent with the Coulomb stress change calculated for a slip distribution having a center of slip close to the trench. This demonstrates the capability of the Coulomb stress change to help constrain the slip distribution that is otherwise difficult to determine. Coulomb stress changes for normal-fault aftershocks near the Japan Trench are found to be strongly dependent on the slip on the shallow portion of the fault. This fact suggests the possibility that the slip on the shallow portion of the fault can be better constrained by combining information of the Coulomb stress change with other available data. The case of normal-fault aftershocks near some trench segment which are calculated to be negatively stressed shows such an example, suggesting that the actual slip on the shallow portion of the fault is larger than that inverted from GPS-derived coseismic displacements.

  7. Geophysical investigation of the Denali fault and Alaska Range orogen within the aftershock zone of the October-November 2002, M = 7.9 Denali fault earthquake

    USGS Publications Warehouse

    Fisher, M.A.; Nokleberg, W.J.; Ratchkovski, N.A.; Pellerin, L.; Glen, J.M.; Brocher, T.M.; Booker, J.

    2004-01-01

    The aftershock zone of the 3 November 2002, M = 7.9 earthquake that ruptured along the right-slip Denali fault in south-central Alaska has been investigated by using gravity and magnetic, magnetotelluric, and deep-crustal, seismic reflection data as well as outcrop geology and earthquake seismology. Strong seismic reflections from within the Alaska Range orogen north of the Denali fault dip as steeply as 25°N and extend to depths as great as 20 km. These reflections outline a relict crustal architecture that in the past 20 yr has produced little seismicity. The Denali fault is nonreflective, probably because this fault dips steeply to vertical. The most intriguing finding from geophysical data is that earthquake aftershocks occurred above a rock body, with low electrical resistivity (>10 Ω·m), that is at depths below ∼10 km. Aftershocks of the Denali fault earthquake have mainly occurred shallower than 10 km. A high geothermal gradient may cause the shallow seismicity. Another possibility is that the low resistivity results from fluids, which could have played a role in locating the aftershock zone by reducing rock friction within the middle and lower crust.

  8. Aftershock Triggering and Estimation of the Coulomb Stress Changes with Approach of Optimally Oriented Fault Planes: Examples of Some Contemporary Earthquakes in Turkey

    NASA Astrophysics Data System (ADS)

    Demirci, Alper

    2013-04-01

    The Coulomb Stress changes due to the some moderate and large earthquakes are shaped according to the orientations of reciever faults or weakness zones along the corresponding seismogenic zones. In some cases, the determination of the fault plane parameters (e.g. length, width, strike, dip) of the receiver faults are more difficult due to the tectonical complexity of the region. Therefore, in order to understand the aftershock distrubition in such areas Coulomb stress changes can be calculated under the assumption of optimally oriented fault planes which increases the spatial correlation between stress changes and aftershock distribution. In the scope of the present sutdy, aftershock distrubiton of some contemporary earthquakes in Turkey (Simav (Mw 5.8), May 2011; Van (Mw 7.0), Oct 2011 and Gulf of Fethiye (Mw 6.1), June 2012) and their coulomb stress changes were correlated. Fault plane parameters of these earthquakes which suggest three different types of focal mechanism were calculated using moment tensor inversion technique and aftershock location data in a period of 30 days for each corresponding events were taken from Kandilli Observatory and Earthquake Research Institute (KOERI) catalog. The focal mechanisms of the selected earthquakes represent normal, strike slip and thrust faulting for the earthquakes of Simav, Gulf of Fethite and Van, respectively. Coulomb Stress Changes were calculated using the open source Matlab based (Coulomb 3.3) codes. The calculations were performed by assuming Poisson's ratio and apparent friction coefficient to be 0.25 and 0.4, respectively. The coulomb stress variations were calculated at fixed depths for each event and aftershocks were selected as ±4 km for corresponding depths. Keeping in mind that the increase of static stress more than 0.5 bar can cause the triggered events in an area, the accordance rates of Coulomb stress changes and aftershock distribution under different tectonic regimes were disscussed. The accordance

  9. Aftershock distribution of a M 2.1 earthquake near a geologic structure boundary in a deep South African gold mine

    NASA Astrophysics Data System (ADS)

    Naoi, M.; Kwiatek, G.; Yabe, Y.; Philipp, J.; Nakatani, M.; Igarashi, T.

    2008-12-01

    We are operating a high-frequency (up to 200 kHz) seismic network at a depth of 3550 m in a deep South African gold mine (Nakatani et al. 2007). An earthquake of M 2.1 occurred within our network on December 27, 2007 (Yabe et al. 2008). In 150 hours following the event, our AE network detected approx. 20,000 events within 100 m from the center of the our network. This aftershock sequence obeys Omori"fs Law. In mines, the number of aftershocks is usually small, but this seems to be simply because vast majority of aftershocks are smaller than detection limit. During the same period, the seismic network of the mine (detection threshold approx. Mw -0.5) detected only nine earthquakes at most. If we assume GR law, comparison of the numbers of aftershocks detected by the both networks suggests that the detection threshold of our AE network is about M - 4. In the area, there is a vertically intruded rock structure made of solidified magma (PG dyke). Thickness is 20 ~ 30 m. This earthquake was expected to be induced by mining around this dyke in 2007 ~ 2008. The boundary position between the dyke and the host rock has been surveyed by the mine, using cores from many boreholes. In addition, our ultrasonic transmission tests have indicated that this contact is generally sharp and there is significant velocity contrast. Velocities within dyke and host rock were fairly uniform (Dyke Vp, Vs are 6.90 km/s, 3.92 km/s respectively, Host Rock Vp Vs are 6.00 km/s, 3.65 km/s respectively). The hypocenter of the M 2.1 earthquake is located within the dyke, not on the contact. The aftershocks lined up on a plane, 30 degrees off vertical; They do not seem to be on the boundary because the dip of the boundary is almost vertical. The distance between them and the closest station of our network was about 6 m. The upper end of aftershock distribution is not clear because of detection limit of our AE network. On the other hand, the downward distribution of the aftershocks seems to be

  10. The 2007 Tocopilla earthquake and its aftershock sequence - A subduction zone earthquake at the edge of the northern Chile seimic gap

    NASA Astrophysics Data System (ADS)

    Eggert, S.; Sobiesiak, M.; Shirzaei, M.

    2010-12-01

    On 14 November 2007 a large Mw 7.7 earthquake occurred in the region of Tocopilla in Northern Chile. The earthquake took place in the southern end of the Northern Chile seismic gap which is supposed to be at the end of its seismic cycle. Studying the event and its aftershock sequence will provide closer insight into the behavior of a subduction zone earthquake at the edge of a subduction zone segment. We present a comprehensive study of the rupture area combining seismic and geodetic data. The aftershock sequence following the earthquake was very well recorded by a local seismic network of 34 short period and broad band stations. The spatial distribution of the aftershock sequence shows a concentration of aftershocks around the north-western part of the Mejillones Peninsula and along the coast up to the Río Loa. The distribution into depth shows that the majority of the hypocenters are located along the subduction interface, reaching down to ~ 50 km depth. In the western part, the aftershock sequence splits into two branches, one heading towards the trench, the other bending into the crust in front of the Mejillones Peninsula. These seismic observations lead to the conclusion that the fault rupture propagated towards the south-west with a fault plane of about 150 km length leaving the shallow part in the north west probably unbroken. To better understand the behavior of the aftershock distribution we model the Coulomb stress transfer along the fault plane. The results show that stresses are increased in the southern part of the rupture area where we find a high concentration of aftershocks. This is consistent with the calculated energy release that shows two main patches along the plate interface rupturing from north to south. The 2007 Tocopilla earthquake is the first large event that occurred inside the Northern Chile seismic gap since the 1877 Iquique event. The rupture process stopped underneath the Mejillones Peninsula, a proposed segment boundary along the

  11. Complex faulting associated with the 22 December 2003 Mw 6.5 San Simeon California, earthquake, aftershocks and postseismic surface deformation

    USGS Publications Warehouse

    McLaren, M.K.; Hardebeck, J.L.; van der Elst, N.; Unruh, J.R.; Bawden, G.W.; Blair, J.L.

    2008-01-01

    We use data from two seismic networks and satellite interferometric synthetic aperture radar (InSAR) imagery to characterize the 22 December 2003 Mw 6.5 San Simeon earthquake sequence. Absolute locations for the mainshock and nearly 10,000 aftershocks were determined using a new three-dimensional (3D) seismic velocity model; relative locations were obtained using double difference. The mainshock location found using the 3D velocity model is 35.704?? N, 121.096?? W at a depth of 9.7 ?? 0.7 km. The aftershocks concentrate at the northwest and southeast parts of the aftershock zone, between the mapped traces of the Oceanic and Nacimiento fault zones. The northwest end of the mainshock rupture, as defined by the aftershocks, projects from the mainshock hypocenter to the surface a few kilometers west of the mapped trace of the Oceanic fault, near the Santa Lucia Range front and the > 5 mm postseismic InSAR imagery contour. The Oceanic fault in this area, as mapped by Hall (1991), is therefore probably a second-order synthetic thrust or reverse fault that splays upward from the main seismogenic fault at depth. The southeast end of the rupture projects closer to the mapped Oceanic fault trace, suggesting much of the slip was along this fault, or at a minimum is accommodating much of the postseismic deformation. InSAR imagery shows ???72 mm of postseismic uplift in the vicinity of maximum coseismic slip in the central section of the rupture, and ???48 and ???45 mm at the northwest and southeast end of the aftershock zone, respectively. From these observations, we model a ???30-km-long northwest-trending northeast-dipping mainshock rupture surface - called the mainthrust - which is likely the Oceanic fault at depth, a ???10-km-long southwest-dipping backthrust parallel to the mainthrust near the hypocenter, several smaller southwest-dipping structures in the southeast, and perhaps additional northeast-dipping or subvertical structures southeast of the mainshock plane

  12. Stress transferred by the 1995 Mw = 6.9 Kobe, Japan, shock: Effect on aftershocks and future earthquake probabilities

    USGS Publications Warehouse

    Toda, S.; Stein, R.S.; Reasenberg, P.A.; Dieterich, J.H.; Yoshida, A.

    1998-01-01

    The Kobe earthquake struck at the edge of the densely populated Osaka-Kyoto corridor in southwest Japan. We investigate how the earthquake transferred stress to nearby faults, altering their proximity to failure and thus changing earthquake probabilities. We find that relative to the pre-Kobe seismicity, Kobe aftershocks were concentrated in regions of calculated Coulomb stress increase and less common in regions of stress decrease. We quantify this relationship by forming the spatial correlation between the seismicity rate change and the Coulomb stress change. The correlation is significant for stress changes greater than 0.2-1.0 bars (0.02-0.1 MPa), and the nonlinear dependence of seismicity rate change on stress change is compatible with a state- and rate-dependent formulation for earthquake occurrence. We extend this analysis to future mainshocks by resolving the stress changes on major faults within 100 km of Kobe and calculating the change in probability caused by these stress changes. Transient effects of the stress changes are incorporated by the state-dependent constitutive relation, which amplifies the permanent stress changes during the aftershock period. Earthquake probability framed in this manner is highly time-dependent, much more so than is assumed in current practice. Because the probabilities depend on several poorly known parameters of the major faults, we estimate uncertainties of the probabilities by Monte Carlo simulation. This enables us to include uncertainties on the elapsed time since the last earthquake, the repeat time and its variability, and the period of aftershock decay. We estimate that a calculated 3-bar (0.3-MPa) stress increase on the eastern section of the Arima-Takatsuki Tectonic Line (ATTL) near Kyoto causes fivefold increase in the 30-year probability of a subsequent large earthquake near Kyoto; a 2-bar (0.2-MPa) stress decrease on the western section of the ATTL results in a reduction in probability by a factor of 140 to

  13. On the c-values of the off-fault aftershocks triggered by the 1995 Kobe earthquake, Japan

    NASA Astrophysics Data System (ADS)

    Sugaya, K.; Hiramatsu, Y.; Furumoto, M.; Katao, H.; Ogata, Y.

    2010-12-01

    The Omori-Utsu law is applicable not only to aftershocks in a source region but also to off-fault aftershocks triggered by the mainshock.In this study, we estimate the c-values using the maximum-likelihood method (Ogata, 1983) from the seismicity activation in the Tamba region induced by the coseismic static stress change due to the 1995 Kobe earthquake of M7.3, Japan. We use earthquakes (M≥1.8) shallower than 20 km from the JMA catalog and remove remarked clusters of the aftershock due to moderate earthquakes with the method of Reasenberg (1985). Our analyzed period is from the occurrence of the earthquake (17 January 1995) to December 1995. The obtained c-values in the divided subregions, near and far to the rupture zone, are 58.1 ± 26.1 days and 164.7 ± 98.0 days, respectively. This is consistent with the rate- and state-dependent friction law of Dieterich (1994) in that the c-values of induced off-fault seismicity are larger than those of the source region depending on the static stress change. We estimate Aσ and the stressing rate after the earthquake in the whole region with the average ΔCFS of 30 kPa (Hashimoto, 1995, 1997) using a grid search following Toda et al. (2005). The friction law’s parameters in the whole region are estimated to be 13.8 ~ 16.2 kPa/yr and 15.0 ~ 16.6 kPa at the stressing rate and Aσ, respectively. Furthermore, we estimate ΔCFSs in the two subregions using the stressing rate of 15.5 kPa/yr and Aσ of 15.5 kPa obtained above. The obtained ΔCFSs in the divided subregions, near and far to the rupture zone, are 39.9 ~ 43.4 kPa and 17.3 ~ 19.9 kPa, respectively. These are coincident with the distribution of ΔCFS drawn by using a geodetic fault model (Hashimoto et al., 1996).

  14. Aftershock Observation of the 22 June 2002 Changoureh-Avaj Earthquake (Mw 6.5), NW Iran

    NASA Astrophysics Data System (ADS)

    Hosseini, S.; Suzuki, S.; Fuji, Y.; Sadeghi, H.; Fatemi Aghda, S.

    2002-12-01

    Iran is located in Alps-Himalayan belt with a high seismicity. On 22 June 2002, a shallow earthquake (Mw6.5) occurred in northwest of Iran, latitude 35.67N and longitude 48.93E (NEIC), for about 225 km west of Tehran, the capital of Iran. This earthquake caused a lot of damages, 1466 wounded and 230 killed persons in the villages with adobe constructions. It is very important to study this earthquake not only for seismological interests but also for knowing fault activity around Tehran with about 7 million population. Taking instruments from Japan one month after the main shock, we installed seismographs in four temporal stations around the damaged area in order to observe aftershocks of this earthquake. The four stations were laid out as a triangle pattern with sides long about 20 km for getting the accurate hypocenters of aftershocks. We decided to put the central station of the triangle near surface fissures caused by the main shock because of no accurate hypocentral data of the mainshock. In each station we installed a high sensitive seismograph (Lennartz-LE3Dlite) with three components. And in one station we installed an acceleration seismograph (Akashi-JEP6A3) with three components. Seismic wave data were recorded in 100Hz sampling by using 16 bit digital recorders (Datamark- LSH8000SH-HD) with 2Gbyte hard disk card and GPS. We observed continuously from July 24 to 29 and succeeded getting good continuous data of all stations during about three days. We started to pick the P and S phase of each event observed in all stations and calculated hypocenter and magnitude of each event by using WIN software in Unix system. By processing of 113 aftershocks, we suggest that most of those epicenters distributed in a square with 25km side in the damaged area. By using NS vertical projection of the hypocenters we can imagine the reverse fault surface with 35 degrees dip to the south from 0 to 15 km depth. Our result is comparable with focal mechanism solutions of USGS and

  15. Characterization of Fault Networks and Diffusion of Aftershock Epicenters From Earthquake Catalogs: Fuzzy C-means Clustering and a Modified ETAS Model

    NASA Astrophysics Data System (ADS)

    Moulik, P.; Tiampo, K. F.

    2009-05-01

    The information on three-dimensional geometry as well as the identification of active fault segments is critical to our assessment of seismic risks. Numerical modeling of the aftershock locations, times and magnitudes are also crucial to characterize a fault zone. In this study, a pattern recognition technique based on the Fuzzy C- means clustering algorithm (Bezdek, 1981) is proposed to allow each earthquake to be associated with different fault segments. The spatial covariance tensor for each cluster and the associated earthquakes are used to find optimal anisotropic clusters and designate them as faults, similar to the OADC method (Ouillon et al., 2008). The location, size and orientation of the reconstructed faults segments are characterized using a fuzzy covariance matrix (Gustafson and Kessel, 1978). The output consists of a set of distinct fault segments along with the associated earthquakes at different fuzzy membership grades (Zadeh, 1965). A resultant matrix consists of the fuzzy membership grade for different earthquakes and corresponding faults segments specifying their degree of association with values from zero to one. The spatial distribution of earthquakes of different magnitudes and membership grades for a fault segment is incorporated in an anisotropic spatial kernel which characterizes the aftershock density at a distance vector in the ETAS model (Kagan and Knopoff, 1987; Ogata, 1988). An optimal spatio-temporal distribution of aftershocks is obtained for each fault segment without considering a priori distributions such as Gaussian or power law (Helmstetter et al., 2006; Helmstetter and Sornette, 2002). The model is tested on the aftershock sequence from the Denali, 2002 earthquake in Alaska and the fault reconstruction results compared with the known faults in the area. Therefore, a new method to incorporate the anisotropic nature of aftershock diffusion along with the reconstruction of fault networks from seismicity catalogs is formulated in

  16. Imaging the high-frequency energy radiation process of a main shock and its early aftershock sequence: The case of the 2008 Iwate-Miyagi Nairiku earthquake, Japan

    NASA Astrophysics Data System (ADS)

    Sawazaki, Kaoru; Enescu, Bogdan

    2014-06-01

    To understand the energy release process that operates at the end of the main shock rupture and start of the aftershock activity, we propose an inversion method that uses continuous high-frequency seismogram envelopes of the main shock and early aftershocks (i.e., events that occur at short times after the main shock). In our approach, the aftershock sequence is regarded as a continuous energy release process, rather than a discrete time series of events. To correct for the contribution of coda wave energy excited by multiple scattering, we use the theoretical envelope synthesized on the basis of the radiative transfer theory as a Green's function. The site amplification factors are corrected considering the conservation of energy flux and using the coda normalization method. The inverted temporal energy release rate for the 2008 MW 6.9 Iwate-Miyagi Nairiku earthquake, Japan, decays following t-1.1, at the lapse time t of 40-900 s after the main shock origin time. This exponent of the decay rate is similar to the p value of the modified Omori law. The amount of estimated energy release is consistent with that calculated from the magnitude listed in the aftershock catalog. Although the uncertainty is large, the location of large energy release at the lapse times of 40-900 s approximately overlaps to that of the aftershocks, which surrounds the large energy release area during the main shock faulting. The maxima of the energy release rate normalized by the average decay rate distributes following a power law, similar to the Gutenberg-Richter law.

  17. Description and performance of a digital mobile satellite terminal

    NASA Technical Reports Server (NTRS)

    Lay, N.; Jedrey, T.; Parkyn, J.; Divsalar, D.

    1990-01-01

    A major goal of the Mobile Satellite Experiment (MSAT-X) program at the Jet Propulsion Lab (JPL) is the development of an advanced digital terminal for use in land mobile satellite communication. The terminal has been developed to minimize the risk of applying advanced technologies to future commercial mobile satellite systems (MSS). Testing with existing L band satellites was performed in fixed, land mobile and aeronautical mobile environments. JPL's development and tests of its mobile terminal have demonstrated the viability of narrowband digital voice communications in a land mobile environment through geostationary satellites. This paper provides a consolidated description of the terminal architecture and the performance of its individual elements.

  18. Mobile Transporter

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Space Shuttle Atlantis, STS-110 mission, deployed this railcar, called the Mobile Transporter, and an initial 43-foot section of track, the S0 (S-zero) truss, preparing the International Space Station (ISS) for future spacewalks. The first railroad in space, the Mobile Transporter will allow the Station's robotic arm to travel up and down the finished truss for future assembly and maintenance. The 27,000-pound S0 truss is the first of 9 segments that will make up the Station's external framework that will eventually stretch 356 feet (109 meters), or approximately the length of a football field. The completed truss structure will hold solar arrays and radiators to provide power and cooling for additional international research laboratories from Japan and Europe that will be attached to the Station. The Space Shuttle Orbiter Atlantis, STS-110 mission, was launched April 8, 2002 and returned to Earth April 19, 2002. STS-110's Extravehicular Activity (EVA) marked the first use of the Station's robotic arm to maneuver spacewalkers around the Station.

  19. Earthquake dynamics. Supershear rupture in a M(w) 6.7 aftershock of the 2013 Sea of Okhotsk earthquake.

    PubMed

    Zhan, Zhongwen; Helmberger, Donald V; Kanamori, Hiroo; Shearer, Peter M

    2014-07-11

    Earthquake rupture speeds exceeding the shear-wave velocity have been reported for several shallow strike-slip events. Whether supershear rupture also can occur in deep earthquakes is unclear, because of their enigmatic faulting mechanism. Using empirical Green's functions in both regional and teleseismic waveforms, we observed supershear rupture during the 2013 moment magnitude (M(w)) 6.7 deep earthquake beneath the Sea of Okhotsk, an aftershock of the large deep earthquake (M(w) 8.3). The M(w) 6.7 event ruptured downward along a steeply dipping fault plane at an average speed of 8 kilometers per second, suggesting efficient seismic energy generation. Comparing it to the highly dissipative 1994 M(w) 8.3 Bolivia earthquake, the two events represent end members of deep earthquakes in terms of energy partitioning and imply that there is more than one rupture mechanism for deep earthquakes.

  20. Security of Mobile Agents on the Internet.

    ERIC Educational Resources Information Center

    Corradi, Antonio; Montanari, Rebecca; Stefanelli, Cesare

    2001-01-01

    Discussion of the Internet focuses on new programming paradigms based on mobile agents. Considers the security issues associated with mobile agents and proposes a security architecture composed of a wide set of services and components capable of adapting to a variety of applications, particularly electronic commerce. (Author/LRW)

  1. Next Step Mobile: Strategy, Services, & PRM

    ERIC Educational Resources Information Center

    Thomas, Lisa Carlucci

    2012-01-01

    As emerging information technologies have driven demand for new library communication channels, there has been increased interest in the use of mobile tools to promote interaction, expand outreach, market programs, and enhance the library experience. Libraries today are at widely different levels of mobile engagement, a gap poised to grow as…

  2. A quantitative study of the energy release in the aftershocks of the Bhuj earthquake, 2001, India, using Lg phase

    NASA Astrophysics Data System (ADS)

    Jayachandran, G.; Abdul Razak, M. M.; Prasad, A. G. V.; Unnikrishnan, E.

    2003-07-01

    The devastating earthquake on 26 January 2001 at Bhuj, India, resulted in large-scale death and destruction of properties of several million US dollars. The moment magnitude of the earthquake was 7.7 and its maximum focal intensity exceeded X in MM scale. The rate of aftershocks of this earthquake, recorded at Gauribidanur seismic array station (GBA), shows a monotonic decay with time superposed with oscillations. For the Indian continent the Lg phase is a prominent arrival at regional distances. The estimate of Lg amplitude is obtained by optimally fitting the Lg wave train to a exponential decay curve. The logarithm of these amplitudes and logarithm of root mean square (rms) value of actual amplitudes of the Lg are calibrated with USGS mb to create a local mbLg magnitude scale. The energy released from these aftershocks is calculated from the rms value of Lg phase. The plot of cumulative energy release with time follows the power law of the form t p, superposed with oscillations. The exponent of the power law, p, is estimated both by a time-window scanning method and by an interpolation method. The value of p is 0.434 for time-window scanning method and 0.432 for the interpolation method. The predominant periods found in the oscillatory part of the cumulative energy, obtained by differencing the observed from the power law fit, are 10.6, 7.9, 5.4, 4.6 and 3.5 h for time-window scanning method. The corresponding periods for interpolation method are 13.4, 11.5, 7.4, 4.2, 3.5, 2.6 and 2.4 h.

  3. The Aftershock Sequence of the 2008 Achaia, Greece, Earthquake: Joint Analysis of Seismicity Relocation and Persistent Scatterers Interferometry

    NASA Astrophysics Data System (ADS)

    Karakostas, Vassilis; Mirek, Katarzyna; Mesimeri, Maria; Papadimitriou, Eleftheria; Mirek, Janusz

    2016-08-01

    On 8 June 2008 an earthquake of Mw6.4 took place in the northwestern part of Peloponnese, Greece. The main shock was felt in a wide area and caused appreciable damage along the main rupture area and particularly at the antipodal of the main shock epicenter fault edge, implying strongly unilateral rupture and stopping phase effects. Abundant aftershocks were recorded within an area of ~50 km in length in the period 8 June 2008-end of 2014, by a sufficient number of stations that secure location accuracy because the regional network is adequately dense in the area. All the available phases from seismological stations in epicentral distances up to 140 km until the end of 2014 were used for relocation with the double difference technique and waveform cross-correlation. A quite clear 3-D representation is obtained for the aftershock zone geometry and dimensions, revealing the main rupture and the activated adjacent fault segments. SAR data are processed using Stanford Method for Persistent Scatterers (StaMPS) and a surface deformation map constructed based on PS point displacement for the coseismic period. A variable slip model, with maximum slip of ~1.0 m located at the lower part of the rupture plane, is suggested and used for calculating the deformation field which was found in adequate agreement with geodetic measurements. With the same slip model the static stress changes were calculated evidencing possible triggering of the neighboring faults that were brought closer to failure. The data availability allowed monitoring the temporal variation of b values that after a continuous increase in the first 5 days, returned and stabilized to 1.0-1.1 in the following years. The fluctuation duration is considered as the equivalent time for fault healing, which appeared very short but in full accordance with the cessation of onto-fault seismicity.

  4. Mobile shearography

    NASA Astrophysics Data System (ADS)

    Kalms, Michael; Jueptner, Werner

    2005-04-01

    By reason of their sensitivity, accuracy and non-contact as well as non-destructive characteristics, modern optical methods such as digital speckle shearography have found an increasing interest for NDT applications on the factory floor. With new carbon filter technologies and other lightweight constructions in aircraft and automotive manufacturing, adapted examination designs and especially developed testing methods are necessary. Shearography as a coherent optical method has been widely accepted as an useful NDT tool. It is a robust interferometric method to determine locations with maximum stress on various material structures. However, limitations of this technique can be found in the bulky equipment components, the interpretation of the complex sherographic result images and at the work with non-cooperative surfaces (dark absorber, bright shining reflectors). We report a mobile shearography system that was especially designed for investigations at aircraft and automotive constructions.

  5. Property Taxes and Elderly Mobility

    PubMed Central

    Shan, Hui

    2009-01-01

    The 2000–05 housing market boom in the U.S. has caused sharp increases in residential property taxes. Housing-rich but income-poor elderly homeowners often complain about rising tax burdens, and anecdotal evidence suggests that some move to reduce their tax burden. There has been little systematic analysis, however, of the link between property tax levels and the mobility rate of elderly homeowners. This paper investigates this link using household-level panel data from the Health and Retirement Study (HRS) and a newly collected data set on state-provided property tax relief programs. These relief programs generate variation in effective property tax burdens that is not due solely to arguably endogenous local community choices about taxes and expenditure programs. The findings provide evidence suggesting that higher property taxes raise mobility among elderly homeowners. The point estimates from instrumental variable estimation using relief programs to generate instruments suggest that a $100 increase in annual property taxes is associated with a 0.73 percentage point increase in the two-year mobility rate for homeowners over the age of 50. This is an eight percent increase from the baseline two-year mobility rate of nine percent. These results are robust to alternative specifications. PMID:20161617