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Sample records for earthquakes occur frequently

  1. Receptor Editing Occurs Frequently during Normal B Cell Development

    PubMed Central

    Retter, Marc W.; Nemazee, David

    1998-01-01

    Allelic exclusion is established in development through a feedback mechanism in which the assembled immunoglobulin (Ig) suppresses further V(D)J rearrangement. But Ig expression sometimes fails to prevent further rearrangement. In autoantibody transgenic mice, reactivity of immature B cells with autoantigen can induce receptor editing, in which allelic exclusion is transiently prevented or reversed through nested light chain gene rearrangement, often resulting in altered B cell receptor specificity. To determine the extent of receptor editing in a normal, non-Ig transgenic immune system, we took advantage of the fact that λ light chain genes usually rearrange after κ genes. This allowed us to analyze κ loci in IgMλ+ cells to determine how frequently in-frame κ genes fail to suppress λ gene rearrangements. To do this, we analyzed recombined VκJκ genes inactivated by subsequent recombining sequence (RS) rearrangement. RS rearrangements delete portions of the κ locus by a V(D)J recombinase-dependent mechanism, suggesting that they play a role in receptor editing. We show that RS recombination is frequently induced by, and inactivates, functionally rearranged κ loci, as nearly half (47%) of the RS-inactivated VκJκ joins were in-frame. These findings suggest that receptor editing occurs at a surprisingly high frequency in normal B cells. PMID:9763602

  2. Loss of BAP1 Expression Occurs Frequently in Intrahepatic Cholangiocarcinoma.

    PubMed

    Andrici, Juliana; Goeppert, Benjamin; Sioson, Loretta; Clarkson, Adele; Renner, Marcus; Stenzinger, Albrecht; Tayao, Michael; Watson, Nicole; Farzin, Mahtab; Toon, Christopher W; Smith, Ross C; Mittal, Anubhav; Samra, Jaswinder S; Hugh, Thomas J; Chou, Angela; Lawlor, Rita T; Weichert, Wilko; Schirmacher, Peter; Sperandio, Nicola; Ruzzenente, Andrea; Scarpa, Aldo; Gill, Anthony J

    2016-01-01

    BRCA1-associated protein 1 (BAP1) is a deubiquitinating enzyme that functions as a tumor suppressor gene. Double hit BAP1 inactivation has been reported in a range of tumor types, including intrahepatic cholangiocarcinoma (ICC), sometimes in association with germline mutation.We performed immunohistochemistry for BAP1 on a well-characterized cohort of 211 ICC patients undergoing surgical resection with curative intent at 3 institutions based in 3 different countries. The median age at diagnosis was 65 years (range, 36.5-86) and 108 (51%) were men. Negative staining for BAP1 (defined as completely absent nuclear staining in the presence of positive internal controls in nonneoplastic cells) occurred in 55 ICCs (26%). BAP1 loss predicted a strong trend toward improved median survival of 40.80 months (95% CI, 28.14-53.46) versus 24.87 months (95% CI, 18.73-31.01), P = 0.059). In a multivariate model including age, sex, BAP1 status, tumor stage, tumor grade, lymphovascular invasion, and tumor size, female sex was associated with improved survival (hazard ratio [HR] 0.54; 95% CI, 0.34-0.85), while advanced tumor stage and lymphovascular invasion (HR 1.89; 95% CI, 1.09-3.28) correlated with decreased survival. In a multivariate analysis, high grade tumors were associated with BAP1 loss (odds ratio [OR] 3.32; 95% CI, 1.29-8.55), while lymphatic invasion was inversely associated with BAP1 loss (OR 0.36; 95% CI, 0.13-0.99).In conclusion, we observed a trend toward improved prognosis in ICC associated with absent expression of BAP1 and an association of BAP1 loss with higher histological grade and absent lymphatic invasion. Female sex was associated with improved survival while advanced tumor stage and lymphatic invasion were associated with decreased survival. PMID:26765459

  3. Loss of BAP1 Expression Occurs Frequently in Intrahepatic Cholangiocarcinoma

    PubMed Central

    Andrici, Juliana; Goeppert, Benjamin; Sioson, Loretta; Clarkson, Adele; Renner, Marcus; Stenzinger, Albrecht; Tayao, Michael; Watson, Nicole; Farzin, Mahtab; Toon, Christopher W.; Smith, Ross C.; Mittal, Anubhav; Samra, Jaswinder S.; Hugh, Thomas J.; Chou, Angela; Lawlor, Rita T.; Weichert, Wilko; Schirmacher, Peter; Sperandio, Nicola; Ruzzenente, Andrea; Scarpa, Aldo; Gill, Anthony J.

    2016-01-01

    Abstract BRCA1-associated protein 1 (BAP1) is a deubiquitinating enzyme that functions as a tumor suppressor gene. Double hit BAP1 inactivation has been reported in a range of tumor types, including intrahepatic cholangiocarcinoma (ICC), sometimes in association with germline mutation. We performed immunohistochemistry for BAP1 on a well-characterized cohort of 211 ICC patients undergoing surgical resection with curative intent at 3 institutions based in 3 different countries. The median age at diagnosis was 65 years (range, 36.5–86) and 108 (51%) were men. Negative staining for BAP1 (defined as completely absent nuclear staining in the presence of positive internal controls in nonneoplastic cells) occurred in 55 ICCs (26%). BAP1 loss predicted a strong trend toward improved median survival of 40.80 months (95% CI, 28.14–53.46) versus 24.87 months (95% CI, 18.73–31.01), P = 0.059). In a multivariate model including age, sex, BAP1 status, tumor stage, tumor grade, lymphovascular invasion, and tumor size, female sex was associated with improved survival (hazard ratio [HR] 0.54; 95% CI, 0.34–0.85), while advanced tumor stage and lymphovascular invasion (HR 1.89; 95% CI, 1.09–3.28) correlated with decreased survival. In a multivariate analysis, high grade tumors were associated with BAP1 loss (odds ratio [OR] 3.32; 95% CI, 1.29–8.55), while lymphatic invasion was inversely associated with BAP1 loss (OR 0.36; 95% CI, 0.13–0.99). In conclusion, we observed a trend toward improved prognosis in ICC associated with absent expression of BAP1 and an association of BAP1 loss with higher histological grade and absent lymphatic invasion. Female sex was associated with improved survival while advanced tumor stage and lymphatic invasion were associated with decreased survival. PMID:26765459

  4. Do characteristic earthquakes occur at intermediate-depths?

    NASA Astrophysics Data System (ADS)

    Papadopoulos, G. A.

    2010-12-01

    The characteristic earthquake model predicts that faults or fault segments tend to generate essentially same size earthquakes having a relatively narrow range of magnitudes near the maximum. The model makes no assumptions about recurrence. Some important implications: (1) on individual faults and fault segments the earthquake occurrence does not follow a log linear G-R relationship that is dominated by the characteristic event, (b) G-R has a low b-value in the moderate-magnitude range, (c) estimates of the likelihood of large earthquake occurrence based on extrapolation of the frequency of occurrence of small earthquakes may be subject to considerable error. Observations in favour of the model were made in several seismotectonic settings around the globe involving shallow and subduction earthquakes. However, other studies on earthquake statistics and observations about the fault behavior indicated patterns of rather uncharacteristic earthquakes. Characteristic earthquakes of intermediate depth (CEID) were not reported so far. Such a type of earthquakes were investigated in the Hellenic Arc, South Aegean Sea, with two independent sets of evidence. In the first, couples of individual large earthquakes occurring in the same intermediate-depth nest were examined, while the second is based on the G-R relation for the entire descending lithospheric slab. On 11 August 1903 and on 8 January 2006 two large earthquakes occurred at the same intermediate-depth (h~70 km) source near Kythira Is, SW Aegean Sea, sharing nearly the same size with Mw of 6.7±0.2 and 6.9, respectively, which are the maximum measured for instrumental intermediate-depth earthquakes in the SW Aegean Sea. The pattern of macroseismic intensity was impressively identical for the two earthquakes, with the maximum intensity observed in the Mitata village of Kythira. For equal epicentral distances high intensities were felt towards the Hellenic Arc and the Mediterranean Sea, while low intensities were felt towards the Aegean marginal sea. This may reflect same pattern of energy radiation and same mode of faulting. From the examination of historical documentary sources and instrumental records it results that candidate earthquake couples of the CEID type were the large earthquakes of 28 March 1846 and 24 June 1870 as well as the large earthquakes of 12 October 1856 and 26 June 1926 in the SE Aegean Sea. However, such a conclusion is unstable since the magnitude determination of the three historical events is quite uncertain. G-R relationships for several segments of the Hellenic Arc showed that deviations from linearity for shallow seismicity could be explained by the characteristic earthquake model (Papadopoulos et al., JGR, 1993, EPS, 2003). CIED-type earthquakes were investigated in the Hellenic Arc by constructing G-R (magnitude-frequency) diagrams for instrumental seismicity data sets with earthquakes of intermediate-depth. Preliminary results showed deviation from the log linear relation that is dominated by the characteristic event in the upper magnitude range, and that the G-R relationship has a low b-value in the moderate-magnitude range. I conclude that the occurrence of characteristic earthquakes at intermediate depths is very likely.

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

    PubMed

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

    2012-06-29

    The scarcity of long geological records of major earthquakes, on different types of faults, makes testing hypotheses of regular versus random or clustered earthquake recurrence behavior difficult. We provide a fault-proximal major earthquake record spanning 8000 years on the strike-slip Alpine Fault in New Zealand. Cyclic stratigraphy at Hokuri Creek suggests that the fault ruptured to the surface 24 times, and event ages yield a 0.33 coefficient of variation in recurrence interval. We associate this near-regular earthquake recurrence with a geometrically simple strike-slip fault, with high slip rate, accommodating a high proportion of plate boundary motion that works in isolation from other faults. We propose that it is valid to apply time-dependent earthquake recurrence models for seismic hazard estimation to similar faults worldwide. PMID:22745426

  6. Could a Sumatra-like megathrust earthquake occur in the south Ryukyu subduction zone?

    NASA Astrophysics Data System (ADS)

    Lin, Jing-Yi; Sibuet, Jean-Claude; Hsu, Shu-Kun; Wu, Wen-Nan

    2014-12-01

    A comparison of the geological and geophysical environments between the Himalaya-Sumatra and Taiwan-Ryukyu collision-subduction systems revealed close tectonic similarities. Both regions are characterized by strongly oblique convergent processes and dominated by similar tectonic stress regimes. In the two areas, the intersections of the oceanic fracture zones with the subduction systems are characterized by trench-parallel high free-air gravity anomaly features in the fore-arcs and the epicenters of large earthquakes were located at the boundary between the positive and negative gravity anomalies. These event distributions and high-gravity anomalies indicate a strong coupling degree of the intersection area, which was probably induced by a strong resistance of the fracture features during the subduction. Moreover, the seismicity distribution in the Ryukyu area was very similar to the pre-seismic activity pattern of the 2004 Sumatra event. That is, thrust-type earthquakes with a trench-normal P-axis occurred frequently along the oceanward side of the mainshock, whereas only a few thrust earthquakes occurred along the continentward side. Therefore, the aseismic area located west of 128°E in the western Ryukyu subduction zone could have resulted from the strong plate locking effect beneath the high gravity anomaly zone. By analogy with the tectonic environment of the Sumatra subduction zone, the occurrence of a potential Sumatra-like earthquake in the south Ryukyu arc is highly likely and the rupture will mainly propagate continentward to fulfill the region of low seismicity (approximately 125° E to 129° E; 23° N to 26.5° N), which may generate a hazardous tsunami.

  7. Frequent excitations of T waves by earthquakes in the South Mariana Arc

    NASA Astrophysics Data System (ADS)

    Chen, Po-Fei; Chen, Kai-Xun; Cheng, Hui-Yun

    2015-02-01

    We used broadband stations in Taiwan and on the Ryukyu Arc islands to investigate T waves induced by earthquakes in the Izu-Bonin-Mariana subduction zone. Of the 48 earthquakes that took place in 2005, 17 earthquakes exhibited T-wave signals consistent with predicted arrival times at stations. Of theses T-excited events, 13 were located in the South Mariana Arc, where the isobaths exhibit strong concave curvature, and were predominantly of normal faulting type. The energies of observed T waves were used quantitatively to evaluate the relative efficiency of receiver-side acoustic-elastic conversions by Gamma calculations. Results show that the steep slopes of offshore bathymetry together with nearly perpendicular angles of back azimuth relative to local isobaths are suitable conditions for T waves observations. In 2010, two clusters of repeated moderate earthquakes in the north and south ends of the Mariana Arc displayed stark contrasts in terms of T-wave excitations despite their normal faulting type. Examining of this discrepancy indicate that a specific curvature together with a specific radiation pattern accounts for the frequent excitations of T waves from shallow earthquakes in the South Mariana Arc.

  8. Earthquakes

    MedlinePlus

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

  9. Prospects for larger or more frequent earthquakes in the los angeles metropolitan region.

    PubMed

    Dolan, J F; Sieh, K; Rockwell, T K; Yeats, R S; Shaw, J; Suppe, J; Huftile, G J; Gath, E M

    1995-01-13

    Far too few moderate earthquakes have occurred within the Los Angeles, California, metropolitan region during the 200-year-long historic period to account for observed strain accumulation, indicating that the historic era represents either a lull between clusters of moderate earthquakes or part of a centuries-long interseismic period between much larger (moment magnitude, M(w), 7.2 to 7.6) events. Geologic slip rates and relations between moment magnitude, average coseismic slip, and rupture area show that either of these hypotheses is possible, but that the latter is the more plausible of the two. The average time between M(w) 7.2 to 7.6 earthquakes from a combination of six fault systems within the metropolitan area was estimated to be about 140 years. PMID:17791339

  10. House pareidolia occurs more frequently than face pareidolia in peripheral vision.

    PubMed

    Lu, Zhengang; Goold, Jessica; Meng, Ming

    2015-01-01

    Human observers sometimes falsely perceive patterns in random images as significant. This phenomenon of pareidolia is frequently reported for seeing faces in particular. On the other hand, the visual system of humans is thought to be hardwired and specially tuned to process faces due to the social significance of faces. If the visual system is highly sensitive to differentiate faces and non-faces, falsely perceiving a face in random images should be very rare. Previous neuroimaging studies have shown fovea preference for face representation (Levy et al., 2001; Malach, Levy, and Hasson, 2002). A recent study, using centrally presented noise patterns, further revealed face-related activation in the right fusiform face area when participants perceived face pareidolia versus letter pareidolia (Liu et al., 2014). However, it remains possible that sensitivity to discriminate faces and non-faces is poor in peripheral vision, leading to face pareidolia may appear to occur more frequently than other types of pareidolia. To test this hypothesis, we presented noise patterns randomly in the left or right visual field, and asked participants to report whether they saw a face or a house. In 80% of the trials, random noise patterns were shown. Whereas in only 10% of the trials a degraded face image was blended with a noise pattern and shown to participants; in the rest 10% of the trails a degraded house image was blended with a noise pattern and shown to participants. Surprisingly, for the random noise trials, participants reported seeing significantly more house pareidolia than face pareidolia. Taking response bias into account, participants were more sensitive for detecting faces than houses even in peripheral vision. No significant differences were found between the left and right hemifields. These results question the notion that human observers naturally tended to falsely "see" face patterns in random images. Meeting abstract presented at VSS 2015. PMID:26326394

  11. Mortality-based Quantification of Injury Severity for Frequently Occurring Motor Vehicle Crash Injuries.

    PubMed

    Weaver, Ashley A; Barnard, Ryan T; Kilgo, Patrick D; Martin, R Shayn; Stitzel, Joel D

    2013-01-01

    The study purpose was to develop mortality-based metrics of injury severity for frequent motor vehicle crash (MVC) injuries. Injury severity was quantified with mortality-based metrics for 240 injuries comprising the top 95% most frequently occurring AIS 2+ injuries in the National Automotive Sampling System - Crashworthiness Data System (NASS-CDS) 2000-2011. Mortality risk ratios (MRRs) were computed by dividing the number of deaths by occurrences for each of the 240 injuries using National Trauma Data Bank Research Data System (NTDB-RDS) MVC cases. MRRMAIS was computed using only patients with a maximum AIS (MAIS) equal to the AIS severity of a given injury. Each injury had an associated MRR and MRRMAIS which ranged from zero (0% mortality representing low severity) to one (100% or universal mortality representing high severity). Injuries with higher MRR and MRRMAIS values are considered more severe because they resulted in a greater proportion of deaths among injured patients. The results illustrated an overall positive trend between AIS severity and the MRR and MRRMAIS values as expected, but showed large variations in MRR and MRRMAIS for some injuries of the same AIS severity. Mortality differences up to 83% (MRR) and 54% (MRRMAIS) were observed for injuries of the same AIS severity. The MRR-based measures of injury severity indicate that some lower AIS severity injuries may result in as many deaths as higher AIS severity injuries. This data-driven determination of injury severity using MRR and MRRMAIS provides a supplement or an alternative to AIS severity classification. PMID:24406961

  12. Assessment of infants with peripherally inserted central catheters: Part 1. Detecting the most frequently occurring complications.

    PubMed

    Pettit, Janet

    2002-12-01

    Inserting, maintaining, and monitoring vascular access are integral components of neonatal care. Advances in vascular access technology have led to the insertion of peripherally inserted central catheters (PICC) to provide stable venous access for early and aggressive parenteral nutrition. Medications that are irritating or damaging, or those with a high osmolality or a nonphysiologic pH, can also be safely administered into the central venous system. The need for repeated peripheral intravenous attempts, as well as the associated pain and physiologic instability, are virtually eliminated once a PICC line is placed. Complications related to PICCs may occur at any phase of therapy: during insertion, while indwelling, or after discontinuing the line. The risk factors associated with PICCs are distinctly different from peripheral intravenous lines because of their long dwell time, central placement, and potential to migrate. Part 1 of Focus on the Physical offers a review of the relevant anatomy of the vascular system and a discussion of the appropriate sites for catheter tip placement. Guidelines for a systematic physical assessment, along with recommendations for standardized PICC documentation, are provided. A review of the signs and symptoms of more frequently occurring complications, such as catheter occlusion and bloodstream infections, is presented to enhance awareness of PICC-specific complications in the neonate and to expedite early detection and treatment. Part 2 of this series will focus on systematic assessment for less common complications such as catheter migration, dislodgement, breakage, and thrombosis, as well as the life-threatening complications of pleural and pericardial effusion. PMID:12881943

  13. PTSD: how frequently should the symptoms occur? The effect on epidemiologic research.

    PubMed

    Karam, E G; Noujeim, J C; Saliba, S E; Chami, A H; Abi Rached, S

    1996-10-01

    The definition of posttraumatic stress disorder (PTSD), like most other psychiatric disorders, relies on descriptive methodology; the formulation of the criteria needed to establish a diagnosis is based on clinical and research findings. We used our data from a community study in Beirut, Lebanon to look at the effect that the frequency of occurrence of individual PTSD symptoms might have on the total PTSD prevalence. We found that the prevalence of PTSD decreased by half if symptoms were required to have occurred at least twice per week. This phenomenon was true whether we considered war or nonwar traumata and was true for the DSM-III-R and the DSM-IV definitions of PTSD. PMID:8902756

  14. Frequent surface rupturing earthquakes along the Carrizo section of the San Andreas Fault since A.D. 1250.

    NASA Astrophysics Data System (ADS)

    Akciz, S. O.; Grant Ludwig, L.; Arrowsmith, J.; Zielke, O.

    2008-12-01

    Paleoseismological investigations of the San Andreas Fault (SAF) in the Carrizo Plain have greatly influenced general models of fault behavior and our understanding of seismic hazard in southern California. Interpretations from seven new excavations across the SAF at the Bidart Fan site in the Carrizo Plain contradict the widely accepted hypothesis that this section of the fault ruptures relatively infrequently and only during large earthquakes with large (~8 m) offsets. Our new paleoseismic data indicate that the Carrizo section of the southern SAF has ruptured six times since ~A.D. 1250. The most recent earthquake, event A, was the 1857 Fort Tejon earthquake. The penultimate earthquake, event B, occurred sometime after A.D. 1620 and not sometime between A.D. 1405 and A.D. 1510, as previously thought. Four earthquakes, events C, D, E and F, occurred between A.D. 1250 and A.D. 1640. Our findings are similar to the new results from the Frazier Mountain site (worked conducted by Scharer and colleagues about 100 km southeast), which indicate 4-5 earthquakes since A.D. 1400. These new data from the northern section of the southern SAF indicate that since about A.D. 1250, the Carrizo section has failed more regularly and more often than previously thought. Additional paleoseismological investigations are needed to expand the record of the past earthquakes and determine the slip associated with each. This information will better constrain the past SAF rupture pattern-an essential element in the assessment of its future behavior.

  15. Identification of symptom domains in ulcerative colitis that occur frequently during flares and are responsive to changes in disease activity

    PubMed Central

    Joyce, Joel C; Waljee, Akbar K; Khan, Tahira; Wren, Patricia A; Dave, Maneesh; Zimmermann, Ellen M; Wang, Sijian; Zhu, Ji; Higgins, Peter DR

    2008-01-01

    Background Ulcerative colitis disease activity is determined by measuring symptoms and signs. Our aim was to determine which symptom domains are frequent and responsive to change in the evaluation of disease activity, which are those defined by three criteria: 1) they occur frequently during flares; 2) they improve during effective therapy for ulcerative colitis; and 3) they resolve during remission. Methods Twenty-eight symptom domains, 16 from standard indices and 12 novel domains identified by ulcerative colitis patient focus groups, were evaluated. Sixty subjects with ulcerative colitis were surveyed, rating each symptom on the three criteria with a 100 mm Visual Analogue Scale. Frequent and responsive symptoms were defined a priori as those whose median Visual Analogue Scale rating for all 3 criteria was significantly greater than 50. Results Thirteen of the 28 symptom domains were identified as both frequent in ulcerative colitis flares and responsive to changes in disease activity. Seven of these 13 symptom domains were novel symptoms derived from ulcerative colitis patient focus groups including stool mucus, tenesmus, fatigue, rapid postprandial bowel movements, and inability to differentiate liquid or gas from solid stool when rectal urgency occurs. Ten of the 16 symptom domains from standard indices were either infrequent or unresponsive to changes in disease activity. Conclusion Only some of the symptoms of ulcerative colitis that are important to patients are included in standard indices, and several symptoms currently measured are not frequent or responsive to change in ulcerative colitis patients. Development of survey measures of these symptom domains could significantly improve the assessment of disease activity in ulcerative colitis. PMID:18803870

  16. Structural damages observed in state buildings after Simav/Turkey earthquake occurred on 19 May 2011

    NASA Astrophysics Data System (ADS)

    Tama, Y. S.

    2012-08-01

    Different levels of damages occurred in state buildings, especially in educational facilities, during the Simav earthquake (ML=5.7) on 19 May 2011. A site survey was carried out in the area after the earthquake, where six state buildings were examined in detail. The results of the survey showed that main reasons for the formation of damages in these buildings are the use of low strength concrete, insufficient reinforcement, inappropriate detailing, and low-quality workmanship. The investigated buildings were also evaluated by P25-rapid assessment method. The method demonstrates that two of the buildings in question are in "high risk band"; the other two fall into "detailed evaluation band", and the rest are in the "low risk band". This figure also matches with the damages observed in the site survey.

  17. Seismogenesis of the lower crustal intraplate earthquakes occurring in Kachchh, Gujarat, India

    NASA Astrophysics Data System (ADS)

    Mandal, Prantik; Pandey, O. P.

    2011-08-01

    Large intraplate continental earthquakes like the 1811-12 New Madrid (M w ⩾ 8.0) and the 2001 Bhuj (Mw7.7) were highly destructive because they occurred in strong crust, but the mechanisms underlying their seismogenesis are not understood. Here we show, using local earthquake velocity tomography, and joint inversion of receiver functions and surface wave group velocity dispersion that the crust and uppermost mantle beneath the 2001 Bhuj earthquake region of western India is far more complex than hitherto known through previous studies. A new image of the crust and underlying mantle lithosphere indicates the presence of a 18-km thick high velocity (Vp: 7.15-8.11 km/s) differentiated crustal and mantle magmatic layer above a hot and thin lithosphere (only 70 km) in the epicentral region of 2001 Bhuj earthquake. This magmatic layer begins at the depth of 24 km and continues down to 42 km depth. Below this region, brittle-ductile transition reaches as deep as the Moho (˜34 km) due to the possible presence of olivine rich mafic magma. Our 1-D velocity structure envisages an initial phase of plume activity (Deccan plume at 65 m.y. ago) resulting in basaltic magma in the eclogitic layers at sub-lithospheric levels, wherein they were subjected to crystallization under ultra-high pressure conditions. Our study also delineates an updoming of Moho (˜4-7 km) as well as asthenosphere (˜6-10 km) below the Kachchh rift zone relative to surrounding areas, suggesting the presence of a confined body of partial melts below the lithosphere-asthenosphere boundary. Restructuring of this warm and thin lithosphere may have been caused due to rifting (at 184 and 88 m.y. ago) and tholeiitic and alkalic volcanism related to the Deccan Traps K/T boundary event (at 65 m.y. ago). Recent study of isotopic ratios proposed that the alkalic basalts found in Kachchh are generated from a CO 2 rich lherzolite partial melts in the asthenosphere that ascended along deep lithospheric rift faults into the lithosphere. It appears that such kind of crust-mantle structure, deepening of brittle-ductile transition and a high input of volatiles containing CO 2 emanating from mantle control the seismogenesis of lower crustal earthquakes in the Kachchh continental rift zone.

  18. Long-Term Prediction of Large Earthquakes: When Does Quasi-Periodic Behavior Occur?

    NASA Astrophysics Data System (ADS)

    Sykes, L. R.

    2003-12-01

    I argue that the prediction of large earthquakes for time scales of a few decades is possible for a number of fault segments along transform and subduction plate boundaries. A key parameter in ascertaining if forecasting is feasible is the size of the coefficient of variation, CV, the standard deviation of inter-event times of large earthquakes that rupture all or most of a given fault segment divided by T, the average repeat time. I address only large events, ones that rupture all or most of the downdip width of the seismogenic zone where velocity-weakening behavior occurs. Historic and paleoseismic data indicate that the segment that ruptured in the great 1946 Nankaido, Japan, earthquake broke 9 times in the previous 1060 years yielding T=118 years and CV=0.16. The adjacent zone that broke in 1944 exhibits similar behavior as does the Copper River delta, the site of 8 paleoseismic events dated by Plafker and Rubin (1994) above the rupture zone of the 1964 Alaska earthquake. Lindh (preceding abstract) finds that many fault segments in California have similar small values of CV. Paleoseismic data for inter-event times at Pallet Creek and Wrightwood, however, indicate a large CV. Those sites at situated along the San Andreas fault near the end of the 1857 rupture zone where slip was much smaller than in the Carrizo plain, rupture in large events to the northwest and southeast overlap and deformation is multibranched as plate motion is transferred in part to the San Jacinto fault. Plate boundary slip is confined to narrow zones along the 1944 and 1946 segments of the Nankai trough but is more diffuse in the Tokai-Suruga Bay region where the Izu Peninsula is colliding with the rest of Honshu and repeat times appear to be longer (and CV perhaps is larger). Dates of uplifted terraces likely give repeat times of inter-plate thrust events that are too long and large estimates of CV since imbricate faults within the upper plate that generate terraces do not rupture in every great earthquake. The 2002 Working Group on large earthquakes in the San Francisco Bay region followed Ellsworth et al. (1999) in adopting much larger values of CV for several critical fault segments and underestimating their likelihood of rupture in the next 30 years. The Working Group also gives considerable weight to a Poisson model, which is in conflict with both renewal processes involving slow stress accumulation and with values of CV near 0.2. The failure of the Parkfield prediction has greatly influenced views in the U.S. about long-term forecasts. The model of the repeated breaking of a single asperity is incorrect since past Parkfield shocks of about magnitude 6 likely did not rupture the same part of the San Andreas fault.

  19. T cell responses in early-stage melanoma patients occur frequently and are not associated with humoral response.

    PubMed

    Pfirschke, Christina; Gebhardt, Christoffer; Zrnig, Inka; Pritsch, Maria; Eichmller, Stefan B; Jger, Dirk; Enk, Alexander; Beckhove, Philipp

    2015-11-01

    Endogenous tumor-specific T cells are detectable in patients with different tumor types including malignant melanoma (MM). They can control tumor growth, have impact on patient survival and correlate with improved clinical response to immune checkpoint therapy. Thus, they may represent a potent biomarker for respective treatment decisions. So far, major target antigens of endogenous MM-reactive T cells have not been determined systematically. Instead, autoantibodies are discussed as surrogate parameter for MM-specific T cells. Throughout a period of more than 60 days after tumor resection, we therefore determined in 38 non-metastasized primary MM patients and in healthy individuals by IFN? ELISpot and bead-based fluorescent multiplex assay major target antigens of spontaneous T cell and humoral responses using a broad panel of MM antigens and assessed the presence and suppressive impact of MM-reactive regulatory T cells (Tregs). We show that MM-reactive T cells are frequent in MM patients, transiently increase after tumor removal and are mostly directed against Melan-A/MART-1, Tyrosinase, NA17-A and p53. MM-specific Tregs were only detected in few patients and inhibited MM-reactive T cells particularly early after tumor resection. Tumor-specific autoantibodies occurred in most patients, but did not correlate with T cell responses. Thus, endogenous antibodies may not be reliable surrogate parameters of MM-reactive T cells. PMID:26160687

  20. Large submarine earthquakes occurred worldwide, 1 year period (June 2013 to June 2014), - contribution to the understanding of tsunamigenic potential

    NASA Astrophysics Data System (ADS)

    Omira, R.; Vales, D.; Marreiros, C.; Carrilho, F.

    2015-03-01

    This paper is a contribution to a better understanding of tsunamigenic potential from large submarine earthquakes. Here, we analyse the tsunamigenic potential of large earthquakes occurred worldwide with magnitudes around Mw 7.0 and greater, during a period of 1 year, from June 2013 to June 2014. The analysis involves earthquake model evaluation, tsunami numerical modelling, and sensors' records analysis in order to confirm the generation or not of a tsunami following the occurrence of an earthquake. We also investigate and discuss the sensitivity of tsunami generation to the earthquake parameters recognized to control the tsunami occurrence, including the earthquake magnitude, focal mechanism and fault rupture depth. A total of 23 events, with magnitudes ranging from Mw 6.7 to Mw 8.1 and hypocenter depths varying from 10 up to 585 km, have been analyzed in this study. Among them, 52% are thrust faults, 35% are strike-slip faults, and 13% are normal faults. Most analyzed events have been occurred in the Pacific Ocean. This study shows that about 39% of the analyzed earthquakes caused tsunamis that were recorded by different sensors with wave amplitudes varying from few centimetres to about 2 m. Some of them caused inundations of low-lying coastal areas and significant damages in harbours. On the other hand, tsunami numerical modeling shows that some of the events, considered as non-tsunamigenic, might trigger small tsunamis that were not recorded due to the absence of sensors in the near-field areas. We also find that the tsunami generation is mainly dependent of the earthquake focal mechanism and other parameters such as the earthquake hypocenter depth and the magnitude. The results of this study can help on the compilation of tsunami catalogs.

  1. Earthquakes

    USGS Publications Warehouse

    Shedlock, Kaye M.; Pakiser, Louis Charles

    1998-01-01

    One of the most frightening and destructive phenomena of nature is a severe earthquake and its terrible aftereffects. An earthquake is a sudden movement of the Earth, caused by the abrupt release of strain that has accumulated over a long time. For hundreds of millions of years, the forces of plate tectonics have shaped the Earth as the huge plates that form the Earth's surface slowly move over, under, and past each other. Sometimes the movement is gradual. At other times, the plates are locked together, unable to release the accumulating energy. When the accumulated energy grows strong enough, the plates break free. If the earthquake occurs in a populated area, it may cause many deaths and injuries and extensive property damage. Today we are challenging the assumption that earthquakes must present an uncontrollable and unpredictable hazard to life and property. Scientists have begun to estimate the locations and likelihoods of future damaging earthquakes. Sites of greatest hazard are being identified, and definite progress is being made in designing structures that will withstand the effects of earthquakes.

  2. ANALYSIS OF LABOUR ACCIDENTS OCCURRING IN DISASTER RESTORATION WORK FOLLOWING THE NIIGATA CHUETSU EARTHQUAKE (2004) AND THE NIIGATA CHUETSU-OKI EARTHQUAKE (2007)

    NASA Astrophysics Data System (ADS)

    Itoh, Kazuya; Noda, Masashi; Kikkawa, Naotaka; Hori, Tomohito; Tamate, Satoshi; Toyosawa, Yasuo; Suemasa, Naoaki

    Labour accidents in disaster-relief and disaster restoration work following the Niigata Chuetsu Earthquake (2004) and the Niigata Chuetsu-oki Earthquake (2007) were analysed and characterised in order to raise awareness of the risks and hazards in such work. The Niigata Chuetsu-oki Earthquake affected houses and buildings rather than roads and railways, which are generally disrupted due to landslides or slope failures caused by earthquakes. In this scenario, the predominant type of accident is a "fall to lower level," which increases mainly due to the fact that labourers are working to repair houses and buildings. On the other hand, landslides and slope failures were much more prevalent in the Niigata Chuetsu Earthquake, resulting in more accidents occurring in geotechnical works rather than in construction works. Therefore, care should be taken in preventing "fall to lower level" accidents associated with repair work on the roofs of low-rise houses, "cut or abrasion" accidents due to the demolition of damaged houses and "caught in or compressed by equipment" accidents in road works and water and sewage works.

  3. Linking fossil reefs with earthquakes: Geologic insight to where induced seismicity occurs in Alberta

    NASA Astrophysics Data System (ADS)

    Schultz, Ryan; Corlett, Hilary; Haug, Kristine; Kocon, Ken; MacCormack, Kelsey; Stern, Virginia; Shipman, Todd

    2016-03-01

    Recently, a significant increase in North American, midcontinent earthquakes has been associated with contemporaneous development of petroleum resources. Despite the proliferation of drilling throughout sedimentary basins worldwide, earthquakes are only induced at a small fraction of wells. In this study, we focus on cases of induced seismicity where high-resolution data are available in the central Western Canada Sedimentary Basin. Our regional comparison of induced earthquake depths suggests basement-controlled tectonics. Complementary to these findings, hypocenters of induced seismicity clusters coincide with the margins of Devonian carbonate reefs. We interpret this spatial correspondence as the result of geographically biased activation potential, possibly as a consequence of reef nucleation preference to paleobathymetric highs associated with Precambrian basement tectonics. This finding demonstrates the importance of geologic/tectonic factors to earthquake induction, in addition to industrial operational parameters. In fact, the observation of induced seismicity silhouetting deep fossil reef systems may be a useful tool to identify future regions with increased seismogenic potential.

  4. Variations of the electromagnetic field that preceded the Peruvian M7.0 earthquake occurred on September 25, 2013

    NASA Astrophysics Data System (ADS)

    Cataldi, Daniele; Cataldi, Gabriele; Straser, Valentino

    2014-05-01

    Through this work we want to highlight the existence of strong electromagnetic emission in the ELF band that preceded the M7, 0 earthquake occurred in Peru on September 25, 2013 at 16:42:42 UTC. The electromagnetic activity data were provided by the monitoring station of Radio Emissions Project (Cecchina, Albano Laziale, Rome, Italy). The monitoring of electromagnetic field takes place 24H24, 7 days on 7, through a prototype of a ELF radio receiver (gain = 57dB) connected to a loop antenna with diameter of 1x1 meters (square section) and contains 25 turns. The antenna is oriented at 306° NW. The data on M7, 0 earthquakes were provided by USGS. The monitoring station has detected intense impulsive emissions starting from 13:55 UTC until, approximately, to 16:40 UTC. These emissions have a very high intensity and have shown just a few hours before the M7.0 earthquake. Seeing as have not been registered radio emission of this intensity for more than 24 before, we think that these signals can be associated with the Peruvian earthquake. Radio emissions with these characteristics have been recorded many times by the monitoring station of Radio Emissions Project, and in all cases have preceded of some hours the M6+ seismic events occurred on a global scale. Key words: Earthquake prediction, ELF, Seismic Electromagnetic Precursor (SEP), Seismic Geomagnetic Precursor (SGP), Geomagnetic emissions.

  5. Long-Term RST Analysis of Anomalous TIR Sequences in Relation with Earthquakes Occurred in Greece in the Period 2004-2013

    NASA Astrophysics Data System (ADS)

    Eleftheriou, Alexander; Filizzola, Carolina; Genzano, Nicola; Lacava, Teodosio; Lisi, Mariano; Paciello, Rossana; Pergola, Nicola; Vallianatos, Filippos; Tramutoli, Valerio

    2016-01-01

    Real-time integration of multi-parametric observations is expected to accelerate the process toward improved, and operationally more effective, systems for time-Dependent Assessment of Seismic Hazard (t-DASH) and earthquake short-term (from days to weeks) forecast. However, a very preliminary step in this direction is the identification of those parameters (chemical, physical, biological, etc.) whose anomalous variations can be, to some extent, associated with the complex process of preparation for major earthquakes. In this paper one of these parameters (the Earth's emitted radiation in the Thermal InfraRed spectral region) is considered for its possible correlation with M ≥ 4 earthquakes occurred in Greece in between 2004 and 2013. The Robust Satellite Technique (RST) data analysis approach and Robust Estimator of TIR Anomalies (RETIRA) index were used to preliminarily define, and then to identify, significant sequences of TIR anomalies (SSTAs) in 10 years (2004-2013) of daily TIR images acquired by the Spinning Enhanced Visible and Infrared Imager on board the Meteosat Second Generation satellite. Taking into account the physical models proposed for justifying the existence of a correlation among TIR anomalies and earthquake occurrences, specific validation rules (in line with the ones used by the Collaboratory for the Study of Earthquake Predictability—CSEP—Project) have been defined to drive a retrospective correlation analysis process. The analysis shows that more than 93 % of all identified SSTAs occur in the prefixed space-time window around ( M ≥ 4) earthquake's time and location of occurrence with a false positive rate smaller than 7 %. Molchan error diagram analysis shows that such a correlation is far to be achievable by chance notwithstanding the huge amount of missed events due to frequent space/time data gaps produced by the presence of clouds over the scene. Achieved results, and particularly the very low rate of false positives registered on a so long testing period, seems already sufficient (at least) to qualify TIR anomalies (identified by RST approach and RETIRA index) among the parameters to be considered in the framework of a multi-parametric approach to t-DASH.

  6. Source Mechanisms of Recent Earthquakes occurred in the Fethiye-Rhodes Basin and Anaximander Seamounts (SW Turkey)

    NASA Astrophysics Data System (ADS)

    Yolsal-Çevikbilen, Seda; Taymaz, Tuncay

    2015-04-01

    Understanding the active tectonics of southern Turkey involves integrating earthquake source parameters with the regional tectonics. In this respect, seismological studies have played important roles in deciphering tectonic deformations and existing stress accumulations in the region. This study is concerned with the source mechanism parameters and spatio-temporal finite-fault slip distributions of recent earthquakes occurred along the Pliny-Strabo Trench (PST), which constitutes the eastern part of the Hellenic subduction zone in the Eastern Mediterranean Sea Region, and along the Fethiye-Burdur Fault Zone (SW Turkey). The study area is located at the junction of the Hellenic and Cyprus arcs along which the African plate plunges northwards beneath the Aegean Sea and the Anatolian block. Bathymetry and topography including large-scale tectonic structures such as the Rhodes Basin, Anaximander Seamounts, the Florence Rise, the Isparta Angle, the Taurus Mountains, and Kyrenia Range also reflect the tectonic complexities in the region. In this study, we performed point-source inversions by using teleseismic long-period P- and SH- and broad-band P-waveforms recorded by the Federation of Digital Seismograph Networks (FDSN) and the Global Digital Seismograph Network (GDSN) stations. We obtained source mechanism parameters and finite-fault slip distributions of recent Fethiye-Rhodes earthquakes (Mw ≥ 5.0) by comparing the shapes and amplitudes of long period P- and SH-waveforms, recorded in the distance range of 30 - 90 degrees, with synthetic waveforms. We further obtained rupture histories of the earthquakes to determine the fault area (fault length and width), maximum displacement, rupture duration and stress drop. Inversion results exhibit that recent earthquakes show left-lateral strike-slip faulting mechanisms with relatively deeper focal depths (h > 40 km) consistent with tectonic characteristics of the region, for example, the June 10, 2012 Fethiye earthquake (Mw: 5.9) can clearly be correlated with the left-lateral Fethiye-Burdur Fault Zone in SW Turkey.

  7. PCDH10 promoter hypermethylation is frequent in most histologic subtypes of mature lymphoid malignancies and occurs early in lymphomagenesis.

    PubMed

    Narayan, Gopeshwar; Xie, Dongxu; Freddy, Allen J; Ishdorj, Ganchimeg; Do, Catherine; Satwani, Prakash; Liyanage, Hema; Clark, Lorraine; Kisselev, Sergey; Nandula, Subhadra V; Scotto, Luigi; Alobeid, Bachir; Savage, David; Tycko, Benjamin; O'Connor, Owen A; Bhagat, Govind; Murty, Vundavalli V

    2013-11-01

    PCDH10 is epigenetically inactivated in multiple tumor types; however, studies in mature lymphoid malignancies are limited. Here, we have investigated the presence of promoter hypermethylation of the PCDH10 gene in a large cohort of well-characterized subsets of lymphomas. PCDH10 promoter hypermethylation was identified by methylation-specific PCR in 57 to 100% of both primary B- and T-cell lymphoma specimens and cell lines. These findings were further validated by Sequenom Mass-array analysis. Promoter hypermethylation was also identified in 28.6% cases of reactive follicular hyperplasia, more commonly occurring in states of immune deregulation and associated with rare presence of clonal karyotypic aberrations, suggesting that PCDH10 methylation occurs early in lymphomagenesis. PCDH10 expression was down regulated via promoter hypermethylation in T- and B-cell lymphoma cell lines. The transcriptional down-regulation resulting from PCDH10 methylation could be restored by pharmacologic inhibition of DNA methyltransferases in cell lines. Both T- and B-cell lymphoma cell lines harboring methylation-mediated inactivation of PCDH10 were resistant to doxorubicin treatment, suggesting that hypermethylation of this gene might contribute to chemotherapy response. PMID:23929756

  8. Tension crack characteristics of surface ruptures of 2 strong earthquakes recently occurred along reverse faults in China

    NASA Astrophysics Data System (ADS)

    Liu, Mingjun; Dai, Aopeng; Zhang, Feng

    2014-05-01

    Field investigations show that there are some tension cracks in the surface ruptures of 2 strong earthquakes recently occurred along reverse faults with strike-slip component in China. Yushu Ms7.1 earthquake occurred on April 14, 2010 in Qinghai, China produced a ~65 km long co-seismic surface rupture with a strike of 310°, which is distributed along Ganzi-Yushu fault that is a reverse fault with strike-slip component in the Qinghai—Tibetan Plateau. The surface rupture of Yushu Ms7.1 earthqake consists of shear, transtensional cracks, transpressional cracks, tension cracks and mole tracks. Some tension cracks occur on the top of small uplifts and the cracking course is from surface to undergound for some tension cracks are shallow. The small uplifts are actually anticlines produced by a regional and deep compressional stress field, but there is a local tensional stress field on the top of the anticlines. Lushan Ms7.0 earthquake on 20 April 20, 2013 in Sichuan, China occurred on the southern segment of the Longmenshan fault zone with a NE strike which is also a reverse fault zone with strike-slip component, but only a co-seismic surface rupture 80m long with a NW strike was found without any NE-striking surface rupture found. The surface rupture shows the form of tension cracks on a top of a small uplift. There are two sets of fresh striation on the surface rupture plane, the striation with larger plunge angles usually only remains above the range 10-20cm below the ground surface, which is covered by the striation with smaller plunging angles. The comprehensive analysis shows that the surface rupture during the Ms7.0 Lushan earthquake at first experienced thrusting, then sinistral strike-slip, and tension cracking at last. In general, some tension cracks of the surface ruptures from Yushu Ms7.1 earthquake on April 14, 2010 and Lushan Ms7.0 earthquake on 20 April 2013 may be produced by the local tensional stress field, but they also reflect the regional and deep compressional stress environment. The work is sponsored by National Natural Science Foundation of China (Grant No. 41174078) and China Spark Program of seismological science and technology (Grant No.XH12068).

  9. Sensitization of skin mast cells with IgE antibodies to Culicoides allergens occurs frequently in clinically healthy horses.

    PubMed

    Wagner, Bettina; Miller, William H; Erb, Hollis N; Lunn, D Paul; Antczak, Douglas F

    2009-11-15

    IgE antibodies are mediators of mast cell degranulation during allergic diseases. The binding of IgE to its high-affinity IgE receptor on mast cell surfaces is called "sensitization" and precedes the development of clinical allergy. Previously, intradermal injection of anti-IgE or the anti-IgG(T) antibody CVS40 induced immediate skin reactions in horses. This suggested that both IgE and IgG(T) sensitize equine skin mast cells. Here, we investigated sensitization to allergen and with IgE or IgG(T) in clinically healthy horses of different age groups. In addition, immediate skin reactions to Culicoides were determined by intradermal testing in non-allergic horses. A total of 14% of the young horses 1-3 years old and 38% of the adult animals showed skin reaction to Culicoides allergen extract. Sensitization with IgE and IgG(T) was evaluated in skin mast cells and peripheral blood basophils to determine whether sensitization with IgG(T) preceded that with IgE in young horses. Anti-IgE stimulated immediate skin reactions in 18 of 21 young horses, but only 7 of them reacted to the anti-IgG(T) antibody CVS40. The equine IgG(T) fraction is composed of IgG3 and IgG5. We used several newly developed monoclonal antibodies to IgG3 and IgG5 for intradermal testing to improve our understanding about the mast cell reaction induced by the anti-IgG(T) antibody CVS40. None of these antibodies induced a skin reaction in young or adult horses. To determine sensitization with IgE in neonates and foals at 6 and 12 weeks of age an in vitro histamine release assay was performed using peripheral blood cells. The histamine concentration released by anti-IgE stimulation from foal basophils increased between birth and 12 weeks of age, while almost no histamine release was observed after anti-IgG(T) treatment of the cells. In summary, IgE was the major immunoglobulin involved in the sensitization of mast cells and basophils in horses at various ages. IgG(T) antibodies did not play a major role in the activation of mast cells or basophils in young horses and their role in the sensitization of adult horses remains unclear. Sensitization to Culicoides allergen in the absence of clinical disease was frequently found in horses of all age groups. Because many clinically healthy horses developed skin reactions to this allergen, sensitization results are useful to diagnose Culicoides-induced allergy only in horses with allergic conditions. PMID:19836083

  10. Earthquakes.

    ERIC Educational Resources Information Center

    Pakiser, Louis C.

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

  11. Earthquakes.

    ERIC Educational Resources Information Center

    Walter, Edward J.

    1977-01-01

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

  12. Combining Seismic Arrays to Image Detailed Rupture Properties of Large Earthquakes: Evidence for Frequent Triggering of Multiple Faults

    NASA Astrophysics Data System (ADS)

    Ishii, M.; Kiser, E.

    2010-12-01

    Imaging detailed rupture characteristics using the back-projection method, which time-reverses waveforms to their source, has become feasible in recent years due to the availability of data from large aperture arrays with dense station coverage. In contrast to conventional techniques, this method can quickly and indiscriminately provide the spatio-temporal details of rupture propagation. Though many studies have utilized the back-projection method with a single regional array, the limited azimuthal coverage often leads to skewed resolution. In this study, we enhance the imaging power by combining data from two arrays, i.e., the Transportable Array (TA) in the United States and the High Sensitivity Seismographic Network (Hi-net) in Japan. This approach suppresses artifacts and achieves good lateral resolution by improving distance and azimuthal coverage while maintaining waveform coherence. We investigate four large events using this method: the August 15, 2007 Pisco, Peru earthquake, the September 12, 2007 Southern Sumatra earthquake, the September 29, 2009 Samoa Islands earthquake, and the February 27, 2010 Maule, Chile earthquake. In every case, except the Samoa Islands event, the distance of one of the arrays from the epicenter requires us to use the direct P wave and core phases in the back-projection. One of the common features of the rupture characteristics obtained from the back-projection analysis is spatio-temporal rupture discontinuities, or discrete subevents. Both the size of the gaps and the timing between subevents suggest that multiple segments are involved during giant earthquakes, and that they trigger slip on other faults. For example, the 2009 Samoa Islands event began with a rupture propagating north for about 15 seconds followed by a much larger rupture that originated 30 km northwest of the terminus of the first event and propagated back toward the southeast. The involvement of multiple rupture segments with different slip characteristics suggest that large earthquakes are more complex compared to smaller events.

  13. Earthquakes

    ERIC Educational Resources Information Center

    Roper, Paul J.; Roper, Jere Gerard

    1974-01-01

    Describes the causes and effects of earthquakes, defines the meaning of magnitude (measured on the Richter Magnitude Scale) and intensity (measured on a modified Mercalli Intensity Scale) and discusses earthquake prediction and control. (JR)

  14. Earthquakes

    MedlinePlus

    ... National Science Foundation National Institute of Standards and Technology Publications If you require more information about any of these topics, the following resources may be helpful. America’s PrepareAthon! How to Prepare for Earthquakes Earthquake Preparedness: ...

  15. Solar wind ion density variations that preceded the M6+ earthquakes occurring on a global scale between 3 and 15 September 2013

    NASA Astrophysics Data System (ADS)

    Cataldi, Gabriele; Cataldi, Daniele; Straser, Valentino

    2015-04-01

    Between 3 and 15 September 2013 on Earth were recorded nine M6+ earthquakes: Canada M6,1 earthquake occurred on 3 September at 20:19 UTC; Japan M6,5 earthquake occurred on 4 September at 00:18 UTC; Canada M6,0 earthquake occurred on 4 September at 00:23 UTC; Alaska M6,5 earthquake occurred on 4 September at 02:32 UTC; Alaska M6,0 earthquake occurred on 4 September at 06:27 UTC; Northern Mid-Atlantic Ridge M6,0 earthquake occurred on 5 September at 04:01 UTC; Guatemala M6,4 earthquake occurred on 7 September at 00:13 UTC; Central East Pacific Rise M6,1 earthquake occurred on 11 September at 12:44 UTC; Alaska M6,1 earthquake occurred on 15 September at 16:21 UTC. The authors analyzed the modulation of solar wind ion density during the period from 1 to 18 September 2013 to determine whether the nine earthquakes were preceded by a variations of the solar wind ion density and for testing a method to be applied in the future also for the prediction of tsunami. The data on ion density used to realize the correlation study are represented by: solar wind ion density variation detected by ACE (Advanced Composition Explorer) Satellite, in orbit near the L1 Lagrange point, at 1.5 million of km from Earth, in direction of the Sun. The instrument used to perform the measurement of the solar wind ion density is the Electron, Proton, and Alpha Monitor (EPAM) instrument, equipped on the ACE Satellite. To conduct the study, the authors have taken in consideration the variation of the solar wind protons density that have these characteristics: differential proton flux 1060-1900 keV (p/cm^2-sec-ster-MeV); differential proton flux 761-1220 keV (p/cm^2-sec-ster-MeV); differential proton flux 310-580 keV (p/cm^2-sec-ster-MeV) and differential proton flux 115-195 keV (p/cm^2-sec-ster-MeV). This data set has been marked with the times (time markers) of M6+ earthquakes occurred on a global scale (the data on M6+ seismic activity are provided in real time by USGS, INGV and the CSEM) between 3 and 15 September 2013. The result of the analysis showed that the nine M6+ earthquakes occurred on a global scale in the time period taken as a reference, were preceded by a significant variation of the solar wind proton density to which was superimposed on a coronal mass ejection (CME) that reached the Earth on September 1, 2013 at 09:19 UTC (± 6 hours, iSWA data). The CME event preceded the first earthquake taken in reference (Canada M6,1 earthquake occurred on September 3 at 20:19 UTC) of about 59 hours.

  16. Location and source properties for the earthquake sequence occurred in the Western Getic Depression (Romania), December 2011 - January 2012

    NASA Astrophysics Data System (ADS)

    Borleanu, Felix; Popescu, Emilia; Diaconescu, Mihai; Radulian, Mircea

    2013-04-01

    A crustal earthquake sequence (40 earthquakes detected and located between 30 December 2011and 10 January 2012) was recently reported in the weastern part of the Getic Depression (about 20 km east from the Tg-Jiu city). The main shock, occurred on January 1, 2012, 23:57 (45.04, 23.56, h=14 km, MD = 4.5) was preceded by 7 foreshocks (MD less than 3.6) within 65-hour interval. The largest aftershocks of magnitude 4.0 and 3.9 occurred within the first 30-minute interval. Seismic source properties are determined using multiple approaches: empirical Green's functions (EGF) deconvolution, spectral ratios technique and acceleration spectra analysis. For EGF and spectral ratios application, we selected co-located foreshocks and aftershocks (2.1 ≤ MD ≤ 4.0) in association to the main event (MD = 4.5). Two different methods were used to calculate the focal mechanism: a method using the polarities of Pg and Pn waves and the other one representing the waveform inversion of moment tensors. Our analysis reveals distinct features, such as the alignment of the foreshocks and aftershocks along a NW-SE direction. The focal mechanisms computed for the three largest events using both techniques are similar, showing a rupture plane in the same NW-SE direction. The relative location of the main shock indicates a unilateral rupture, from SE toward NW. In parallel, source parameters are retrieved from the analysis of the accelerometer spectra. The resulted source time functions are similar from one station to the other, suggesting negligible source directivity effects for the study events. The shape of the deconvolved source time function for the main shock of 1 January 2012 indicates a homogeneous rupture process in the focus.

  17. Large submarine earthquakes that occurred worldwide in a 1-year period (June 2013 to June 2014) - a contribution to the understanding of tsunamigenic potential

    NASA Astrophysics Data System (ADS)

    Omira, R.; Vales, D.; Marreiros, C.; Carrilho, F.

    2015-10-01

    This paper is a contribution to a better understanding of the tsunamigenic potential of large submarine earthquakes. Here, we analyze the tsunamigenic potential of large earthquakes which have occurred worldwide with magnitudes around Mw = 7.0 and greater during a period of 1 year, from June 2013 to June 2014. The analysis involves earthquake model evaluation, tsunami numerical modeling, and sensors' records analysis in order to confirm the generation of a tsunami (or lack thereof) following the occurrence of an earthquake. We also investigate and discuss the sensitivity of tsunami generation to the earthquake parameters recognized to control tsunami occurrence, including the earthquake location, magnitude, focal mechanism and fault rupture depth. Through this analysis, we attempt to understand why some earthquakes trigger tsunamis and others do not, and how the earthquake source parameters are related to the potential of tsunami generation. We further discuss the performance of tsunami warning systems in detecting tsunamis and disseminating the alerts. A total of 23 events, with magnitudes ranging from Mw = 6.7 to Mw = 8.1, have been analyzed. This study shows that about 39 % of the analyzed earthquakes caused tsunamis that were recorded by different sensors with wave amplitudes varying from a few centimeters to about 2 m. Tsunami numerical modeling shows good agreement between simulated waveforms and recorded waveforms, for some events. On the other hand, simulations of tsunami generation predict that some of the events, considered as non-tsunamigenic, caused small tsunamis. We find that most generated tsunamis were caused by shallow earthquakes (depth < 30 km) and thrust faults that took place on/near the subduction zones. The results of this study can help the development of modified and improved versions of tsunami decision matrixes for various oceanic domains.

  18. Fusarium musae infected banana fruits as potential source of human fusariosis: May occur more frequently than we might think and hypotheses about infection

    PubMed Central

    Triest, David; Piérard, Denis; De Cremer, Koen; Hendrickx, Marijke

    2016-01-01

    ABSTRACT The banana fruit infecting fungus Fusarium musae was originally known as a distinct population within Fusarium verticillioides. However, recently, Fusarium musae was installed as a separate species and the first cases of human infection associated with Fusarium musae were found. In this article, we report an additional survey indicating that human pathogenic Fusarium musae infections may occur more frequently than we might think. Moreover, we evaluate the hypotheses on how infection can be acquired. A first hypothesis is that banana fruits act as carriers of Fusarium musae spores and thereby be the source of human infection with Fusarium musae. Acquisition is likely to be caused through contact with Fusarium musae contaminated banana fruits, either being imported or after traveling of the patient to a banana-producing country. An alternative hypothesis is that Fusarium musae is not only present on banana fruits, but also on other plant hosts or environmental sources. PMID:27195070

  19. Earthquake!

    ERIC Educational Resources Information Center

    Hernandez, Hildo

    2000-01-01

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

  20. IDH mutations occur frequently in Chinese glioma patients and predict longer survival but not response to concomitant chemoradiotherapy in anaplastic gliomas.

    PubMed

    Qi, Song-Tao; Yu, Lei; Lu, Yun-Tao; Ou, Yang-Hui; Li, Zhi-Yong; Wu, Lan-Xiao; Yao, Fei

    2011-12-01

    Mutations in the isocitrate dehydrogenase 1 and 2 genes (IDH1 and IDH2) appear to occur frequently and selectively in gliomas. Our aim was to assess whether IDH mutations are common in Chinese glioma patients and whether the mutations predict good response to concomitant chemoradiotherapy. In this study IDH1 and IDH2 mutations were detected in a series of 203 gliomas. IDH1 mutations were present in 75 of the 203 cases (36.9%) while IDH2 mutations in 5 of the 203 cases (2.5%). No tumor was mutated in both IDH1 and IDH2. IDH1/2 mutations were associated with prolonged overall survival in the whole series of patients exclusive of pilocytic astrocytoma (P<0.001), WHO grade Ⅱ patients who received no adjuvant therapy after surgery (P=0.014) and WHO grade Ⅲ patients who received concomitant chemoradiotherapy (standard schedule) after surgery (P=0.033). Furthermore, there was no correlation between IDH1/2 mutations and reponse to concomitant chemoradiotherapy in anaplastic gliomas. Our results suggest that IDH1 mutations also occur freuqently in Chinese glioma patients but the frequency of IDH1 mutations is below the findings reported by North American and European groups. Furthermore, we confirm the prognostic significance of IDH1/2 mutations in gliomas, but the mutations cannot predict a favorable response to concomitant chemoradiotherapy in anaplastic gliomas. PMID:21874255

  1. Solar wind proton density variations that preceded the M6+ earthquakes occurring on a global scale between 17 and 20 April 2014

    NASA Astrophysics Data System (ADS)

    Cataldi, Gabriele; Cataldi, Daniele; Straser, Valentino

    2015-04-01

    Between 17 and 20 April 2014 on Earth were recorded six M6+ earthquakes: Balleny Islands region M6,2 earthquake occurred on 17 April at 15:06 UTC; Solomon Islands M6,1 earthquake occurred on 18 April at 04:13 UTC; Mexico M7,2 earthquake occurred on 18 April at 14:27 UTC; Papua New Guinea M6,6 earthquake occurred on 19 April at 01:04 UTC; Papua New Guinea M7,5 earthquake occurred on 19 April at 13:28 UTC; Papua New Guinea M6,2 earthquake occurred on 20 April at 00:15 UTC. The authors analyzed the modulation of solar wind ion density during the period from 14 to 23 April 2014 to determine whether the six earthquakes were preceded by a variations of the solar wind ion density and for testing a method to be applied in the future also for the prediction of tsunami. The data on ion density used to realize the correlation study are represented by: solar wind ion density variation detected by ACE (Advanced Composition Explorer) Satellite, in orbit near the L1 Lagrange point, at 1.5 million of km from Earth, in direction of the Sun. The instrument used to perform the measurement of the solar wind ion density is the Electron, Proton, and Alpha Monitor (EPAM) instrument, equipped on the ACE Satellite. To conduct the study, the authors have taken in consideration the variation of the solar wind protons density that have these characteristics: differential proton flux 1060-1900 keV (p/cm^2-sec-ster-MeV); differential proton flux 761-1220 keV (p/cm^2-sec-ster-MeV); differential proton flux 310-580 keV (p/cm^2-sec-ster-MeV) and differential proton flux 115-195 keV (p/cm^2-sec-ster-MeV). This data set has been marked with the time data (time markers) of M6+ earthquakes occurred on a global scale between 17 and 20 April 2014 (the data on M6+ seismic activity are provided in real time by USGS, INGV and CSEM). The result of the analysis showed that the six M6+ earthquakes occurred on a global scale in the time period taken as a reference, were preceded by a significant variation of the solar wind proton density started on April 17, 2014, approximately at 01:00 UTC. The beginning of this increase preceded the first seismic event taken in reference (Balleny Islands region M6,2 earthquake occurred on April 17 at 15:06 UTC) of about 14 hours.

  2. The reasons why the M9 earthquake in the northeastern Japan subduction zone could not be anticipated and why it really occurred

    NASA Astrophysics Data System (ADS)

    Matsuzawa, T.; Iio, Y.

    2011-12-01

    The M9 Tohoku earthquake on 11 March 2011 had a great impact on the seismologists all over the world. This is because the northeastern Japan subduction zone was one of the most investigated subduction zones and the interplate coupling there was thought to be too weak to generate M9 earthquakes. The bases of the judgment of weak coupling are as follows: (1) The portion of the Pacific plate subducting beneath the subduction zone is older than 100 my, which is older than most of the other ocean floors in the world. Note that although some researchers have casted doubt on the relationship between the M9 potential and plate convergence rate and back-arc spreading proposed by Ruff and Kanamori (1980) after the 2004 M9 Sumatra-Andaman earthquake (e.g., McCaffrey, 2007, 2008; Stein and Okal, 2007), the dependency on the age of the oceanic plate had not been rejected. (2) Around 100 year geodetic survey shows dilatational areal strain is dominant in Tohoku (northeastern Honshu, Japan) (Hashimoto, 1990; Ishikawa and Hashimoto, 1999), indicating all the 'locked' areas on the plate boundary might be loosened by M7 earthquakes occurring with repeating intervals of several tens of years. (3) Although the analyses of GPS (e.g., Suwa et al., 2006) and small repeating earthquake data (Uchida and Matsuzawa, 2011) indicate a large 'locked' area off southern Tohoku, the data in the late 2000s show large portions of the locked area seemed to be released by large earthquakes of M6-7 and their afterslip. (4) The activity of moderate-sized earthquakes there is the highest in Japan. (5) Large interplate earthquakes with M6 or larger are usually followed by large afterslip whose scalar moment is sometimes as large as that of the seismic slip of the main shock. Moreover, Hasegawa et al. (2011) shows that the stress on the plate boundary was not large according to the stress rotation after the M9 earthquake. All of these observations indicate that the plate boundary was not strongly locked over 100 years. Then why did the M9 earthquake really occur there? The reason is still under the debate. One of the probable explanations is that the plate boundary had been weakly coupled but the slip of the M9 earthquake was exceptionally large releasing total stress on the boundary. The Pacific plate descending beneath Tohoku is old and cold but the inclination of the plate is less than around 30 degrees and interplate earthquakes can occur as deep as 60 km because the plate is very cold. The shallow subduction angle and deep sesimogenic limit causesd the seismogenic plate boundary as wide as more than 200 km, which was large enough to accumulate slip deficit of more than 20m without large stress increase (Iio et al., 2011). Most of the aftershocks occurring in the hanging plate are of normal fault type (Asano et al., 2011) indicating the seismic slip of the M9 earthquake was overshot (Ide et al., 2011), which might be caused by thermal pressurization of pore fluid (Mitsui and Iio, 2011).

  3. Moment tensor inversion for two micro-earthquakes occurring inside the Háje gas storage facilities, Czech Republic

    NASA Astrophysics Data System (ADS)

    Benetatos, Christoforos; Málek, Jiří; Verga, Francesca

    2013-04-01

    Broadband data from the Příbram seismological network was used to investigate the source of two earthquakes, with magnitudes M w = 0.2 and 0.4 respectively, occurring in the period of October-November 2009 in the Háje natural gas storage area (Czech Republic). Both events were located inside the limits of the storage area and at depths similar to those of the underground caverns where the gas is stored. We applied an inversion technique using the software ISOLA for moment tensor retrieval in order to assess the source process of both events and recognize whether a significant isotropic component existed that could be interpreted as a possible cavern collapse. We also performed an uncertainty analysis so as to confirm the reliability of the focal mechanism solutions and we controlled the consistency between the inverted focal mechanisms and those calculated using the P-waves first motions. Our results showed that the nodal plane orientation, the centroid depth, and the magnitude remained stable. Furthermore, we calculated synthetic waveforms for collapse-type ruptures and compared them with the original records. The match between the synthetic and the original data was very poor supporting the interpretation of the shear character of the events. The combination of the inversion results, which indicated significant double-couple components and of the synthetic tests, which supported the inexistence of an isotropic component at the source, led to the conclusion that the possibility of rocks falling from the ceiling of the caverns or a cavern collapse is highly unlikely.

  4. On the behavior of site effects in central Mexico (the Mexican volcanic belt - MVB), based on records of shallow earthquakes that occurred in the zone between 1998 and 2011

    NASA Astrophysics Data System (ADS)

    Clemente-Chavez, A.; Zúñiga, F. R.; Lermo, J.; Figueroa-Soto, A.; Valdés, C.; Montiel, M.; Chavez, O.; Arroyo, M.

    2014-06-01

    The Mexican volcanic belt (MVB) is a seismogenic zone that transects the central part of Mexico with an east-west orientation. The seismic risk and hazard of this seismogenic zone has not been studied in detail due to the scarcity of instrumental data as well as because seismicity in the continental regime of central Mexico is not too frequent. However, it is known that there are precedents of large earthquakes (Mw > 6.0) that have taken place in this zone. The valley of Mexico City (VM) is the sole zone, within the MVB, that has been studied in detail. Studies have mainly focused on the ground amplification during large events such as the 1985 subduction earthquake that occurred off coast of Michoacán. The purpose of this article is to analyze the behavior of site effects in the MVB zone based on records of shallow earthquakes (data not reported before) that occurred in the zone between 1998 and 2011. We present a general overview of site effects in the MVB, a classification of the stations in order to reduce the uncertainty in the data when obtaining attenuation parameters in future works, as well as some comparisons between the information presented here and that presented in previous studies. A regional evaluation of site effects and Fourier acceleration spectrum (FAS) shape was estimated based on 80 records of 22 shallow earthquakes within the MVB zone. Data of 25 stations were analyzed. Site effects were estimated by using the horizontal-to-vertical spectral ratio (HVSR) methodology. The results show that seismic waves are less amplified in the northeast sites of the MVB with respect to the rest of the zone and that it is possible to classify two groups of stations: (1) stations with negligible site amplification (NSA) and (2) stations with significant site amplification (SSA). Most of the sites in the first group showed small (<3) amplifications while the second group showed amplifications ranging from 4 to 6.5 at frequencies of about 0.35, 0.75, 15 and 23 Hz. With these groups of stations, average levels of amplification were contrasted for the first time with those caused by the subduction zone earthquakes. With respect to the FAS shapes, most of them showed similarities at similar epicentral distances. Finally, some variations of site effects were found when compared to those obtained in previous studies on different seismicity regions. These variations were attributed to the location of the source. These aspects help to advance the understanding about the amplification behavior and of the expected seismic risk on central Mexico due to large earthquakes within the MVB seismogenic zone.

  5. Earthquake.

    PubMed

    Cowen, A R; Denney, J P

    1994-04-01

    On January 25, 1 week after the most devastating earthquake in Los Angeles history, the Southern California Hospital Council released the following status report: 928 patients evacuated from damaged hospitals. 805 beds available (136 critical, 669 noncritical). 7,757 patients treated/released from EDs. 1,496 patients treated/admitted to hospitals. 61 dead. 9,309 casualties. Where do we go from here? We are still waiting for the "big one." We'll do our best to be ready when Mother Nature shakes, rattles and rolls. The efforts of Los Angeles City Fire Chief Donald O. Manning cannot be overstated. He maintained department command of this major disaster and is directly responsible for implementing the fire department's Disaster Preparedness Division in 1987. Through the chief's leadership and ability to forecast consequences, the city of Los Angeles was better prepared than ever to cope with this horrendous earthquake. We also pay tribute to the men and women who are out there each day, where "the rubber meets the road." PMID:10133439

  6. PRE SEISMIC ANOMALIES REVEALED IN THE AREA WHERE THE ABRUZZO EARTHQUAKE (M = 6.3) OCCURRED ON APRIL 6, 2009

    NASA Astrophysics Data System (ADS)

    Biagi, P. F.; Castellana, L.; Maggipinto, T.; Ermini, A.

    2009-12-01

    Since 1996, the intensity of CLT (f=189 kHz, Sicily, Italy), MCO (f=216 kHz, France) and CZE (f=270 kHz, Czech Republic) broadcast signals has been collected with a ten minutes sampling rate by a receiver operating in a place located about 13 km far from the epicenter of the Abruzzo earthquake (M=6.3, April 6, 2009). During March 2009, the old receiver was substituted with a new one for measuring, with one minute sampling rate, the intensity of five VLF signals and five LF signals radiated by transmitters located in different zone of Europe. Two of the previous transmitters are included among them. In the period March 31-April 1 the intensity of the MCO radio signal dropped and this drop was observed only in this signal. The possibility that the drop was connected to problems in the transmitter or in the receiver was investigated and excluded. So, the drop indicates a defocusing of the radiated signal. Since none particular meteorological situation along the path transmitter-receiver happened, the defocusing must be related to other causes. The possibility that it is a precursor of the Abruzzo earthquake is presented. Beside, the flow rate of a natural spring located in the same place of the receiver is being sampled from 1992. During September-October 2008 the flow rate was abnormal with respect to all the previous periods. Also this anomaly takes the shape of a precursor of the Abruzzo earthquake. Probably, it is mainly related to the seismic sequence that started in the zone in the middle of January 2009 and that lasted up to the earthquake.

  7. Investigation of geomagnetic field and hydro-geochemical precursors of several earthquakes occurred in the territory of Armenia and Iran

    NASA Astrophysics Data System (ADS)

    Yenanov, M.; Vardanyan, G.; Adibekyan, M.

    The seismic regime observations in the territory of Armenia are performed permanently on the seven geomagnetic and seven geochemical observation stations. The full T-vector and the gases, macro-components, micro-components and some parameters are daily investigated. All the regime geomagnetic field and geo-chemical observations are accompanied with metrological works on all the stages. All observation stations and drills are located in the zones of active faults. Selected location of observation stations and drills allows observing the geomagnetic and geochemical reaction on the earthquakes not only in the territory of Armenia but also in the territory of Turkey, Georgia, Azerbaijan and Iran. The relation between the change of geomagnetic full T-vector time series field and micro- and macro-components in underground waters and the process of strong seismic events preparing is well studied. A large amount of pre-, co-, and post-seismic anomalies of physical and chemical parameters of underground waters are defined, also defined the geomagnetic field peculiarities in the investigating area. With the aim to current seismic hazard assessment in the territory of Armenia and adjacent regions the research of geomagnetic and geochemical data was carried out and earthquake precursors had been distinguished. In this paper the techniques of data processing and results of analysis of geomagnetic field peculiarities and hydro-geochemical earthquake precursors.

  8. Unexpectedly frequent occurrence of very small repeating earthquakes (-5.1 ≤ Mw ≤ -3.6) in a South African gold mine: Implications for monitoring intraplate faults

    NASA Astrophysics Data System (ADS)

    Naoi, Makoto; Nakatani, Masao; Igarashi, Toshihiro; Otsuki, Kenshiro; Yabe, Yasuo; Kgarume, Thabang; Murakami, Osamu; Masakale, Thabang; Ribeiro, Luiz; Ward, Anthony; Moriya, Hirokazu; Kawakata, Hironori; Nakao, Shigeru; Durrheim, Raymond; Ogasawara, Hiroshi

    2015-12-01

    We observed very small repeating earthquakes with -5.1 ≤ Mw ≤ -3.6 on a geological fault at 1 km depth in a gold mine in South Africa. Of the 851 acoustic emissions that occurred on the fault during the 2 month analysis period, 45% were identified as repeaters on the basis of waveform similarity and relative locations. They occurred steadily at the same location with similar magnitudes, analogous to repeaters at plate boundaries, suggesting that they are repeat ruptures of the same asperity loaded by the surrounding aseismic slip (background creep). Application of the Nadeau and Johnson (1998) empirical formula (NJ formula), which relates the amount of background creep and repeater activity and is well established for plate boundary faults, to the present case yielded an impossibly large estimate of the background creep. This means that the presently studied repeaters were produced more efficiently, for a given amount of background creep, than expected from the NJ formula. When combined with an independently estimated average stress drop of 16 MPa, which is not particularly high, it suggests that the small asperities of the presently studied repeaters had a high seismic coupling (almost unity), in contrast to one physical interpretation of the plate boundary repeaters. The productivity of such repeaters, per unit background creep, is expected to increase strongly as smaller repeaters are considered (∝ Mo -1/3 as opposed to Mo -1/6 of the NJ formula), which may be usable to estimate very slow creep that may occur on intraplate faults.

  9. On the behavior of site effects in Central Mexico (the Mexican Volcanic Belt - MVB), based on records of shallow earthquakes that occurred in the zone between 1998 and 2011

    NASA Astrophysics Data System (ADS)

    Clemente-Chavez, A.; Zúñiga, F. R.; Lermo, J.; Figueroa-Soto, A.; Valdés, C.; Montiel, M.; Chavez, O.; Arroyo, M.

    2013-11-01

    The Mexican Volcanic Belt (MVB) is a seismogenic zone that transects the central part of Mexico with an east-west orientation. The risk and hazard seismic of this seismogenic zone has not been studied at detail due to the scarcity of instrumental data as well as because seismicity in the continental regimen of Central Mexico is not too frequent, however, it is known that there are precedents of large earthquakes (Mw > 6.0) that have taken place in this zone. The Valley of Mexico City (VM) is the sole zone, within the MVB, which has been studied in detail; mainly focusing on the ground amplification during large events such as the 1985 subduction earthquake that occurred in Michoacan. The purpose of this article is to analyze the behavior of site effects in the MVB zone based on records of shallow earthquakes (data not reported before) that occurred in the zone between 1998 and 2011. We present a general overview of site effects on the MVB, a classification of the stations in order to reduce the uncertainty in the data to obtain attenuation parameters in future works, and some comparisons between the information presented here and that presented in previous studies. A regional evaluation of site effects and Fourier Acceleration Spectrum (FAS) shape was estimated based on 80 records of 22 shallow earthquakes within the MVB zone. Data of 25 stations were analyzed. Site effects were estimated by using the Horizontal-to-Vertical Spectral Ratio (HVSR) methodology. The results show that seismic waves are less amplified in the northeast sites of the MVB with respect to the rest of the zone and that it is possible to classify two groups of stations: (1) stations with Negligible Site Amplification (NSA) and (2) stations with Significant Site Amplification (SSA). Most of the sites in the first group showed small (< 3) amplifications while the second group showed amplifications ranging from 4 to 6.5 at frequencies of about 0.35, 0.75, 15 and 23 Hz. With these groups of stations, average levels of amplification were contrasted for the first time with those caused by the subduction zone earthaquakes. With respect to the FAS shapes, most of them showed similarities at similar epicentral distances. Finally, some variations of site effects were found when compared to those obtained in previous studies on different seismicity regions. These variations were attributed to the location of the source. These aspects help to advance the understanding about the amplification behavior and of the expected seismic risk on the Central Mexico due to large earthquakes within the MVB seismogenic zone.

  10. Biased hypermutation occurred frequently in a gene inserted into the IC323 recombinant measles virus during its persistence in the brains of nude mice

    SciTech Connect

    Otani, Sanae; Ayata, Minoru; Takeuchi, Kaoru; Takeda, Makoto; Shintaku, Haruo; Ogura, Hisashi

    2014-08-15

    Measles virus (MV) is the causative agent of measles and its neurological complications, subacute sclerosing panencephalitis (SSPE) and measles inclusion body encephalitis (MIBE). Biased hypermutation in the M gene is a characteristic feature of SSPE and MIBE. To determine whether the M gene is the preferred target of hypermutation, an additional transcriptional unit containing a humanized Renilla reniformis green fluorescent protein (hrGFP) gene was introduced into the IC323 MV genome, and nude mice were inoculated intracerebrally with the virus. Biased hypermutation occurred in the M gene and also in the hrGFP gene when it was inserted between the leader and the N gene, but not between the H and L gene. These results indicate that biased hypermutation is usually found in a gene whose function is not essential for viral proliferation in the brain and that the location of a gene in the MV genome can affect its mutational frequency. - Highlights: • Wild-type MV can cause persistent infections in nude mice. • Biased hypermutation occurred in the M gene. • Biased hypermutation occurred in an inessential gene inserted between the leader and the N gene.

  11. Temporal and Spatial Evolution of Anisotropic Parameters before and after the Earthquake Occurred in the San Andreas Fault

    NASA Astrophysics Data System (ADS)

    SHI, Y.; Liu, L.; Gao, Y.

    2013-12-01

    Shear-wave splitting (SWS) due to stress-aligned anisotropy have been widely observed and extensively used to determine the stress state or material property anisotropy in the shallow crust. It is generally accepted that the polarization of the fast shear-wave indicates the orientation of the aligned micro-cracks in the rock, and the time-delays of slow shear-wave splitting estimate the density of micro-cracks, and bring with information of stress accumulation and temporal variation in the crust. However, the temporal and spatial characteristic of crustal anisotropy is very constrained by the limited distributions of stations and seismicity. In addition, the strict requirement of shear-wave window and the availability of high-quality events literally restrict the crustal anisotropy research. The seismic wave's propagation, as an effective method, is used for geological structure research, but also for the analysis of rock properties. At present, the most widely used simulation approach for seismic anisotropy study is the adoption of transversely isotropic medium. Whereas the realistic complex crustal anisotropic structure of typical activated regions cannot be explained at first order by the transversely isotropic medium. The earth media, especially in certain active tectonic deformation zones, can be regarded as inhomogeneous with directivities under the action of local stress field. It is equivalent to take that anisotropy medium as directive heterogeneity. In this research, anisotropic medium be regarded as the directional arrangement of molecular scale heterogeneity and be described by heterogeneous medium in a large scale. We use the isotropic PSTD algorithm to conduct the simulation. Through numerical simulation with PSTD technique, we get the anisotropic characteristics in the equivalency of the inhomogeneous medium, which build by the correlation length and variation of radon velocity. The San Andreas Fault (SAF) is one of the most renowned faults in the world due to the 1906 San Francisco earthquake. The SWS research at the vicinity of the Parkfield of SAF show the orientations of fast shear-wave for stations on the main fault associated with the strike main fault. In addition, outside of the fault zone, the orientations of fast shear wave are preferentially oriented parallel to the orientation of regional principle compressive stress. In the study, based on the distribution of crustal anisotropy parameter by analyzing SWS from local earthquake data prior to and following the 28 September 2004 Parkfield M6.0 earthquakes as the priori information, arranging each isotropic media unit as a complex structure with the constraint of velocity structure and geometry of the faults, we construct a complex anisotropic model and simulate the characteristic of wave's propagation in this model. Finally, comparing the anisotropic characteristic of simulated seismic wave with the observed seismic wave, we get a more accurate and reasonable variety characteristics of anisotropic parameters, and then we will discuss the temporal and spatial evolution of anisotropic parameters before and after the before and after the big earthquake.

  12. TERT PROMOTER MUTATIONS OCCUR FREQUENTLY IN GLIOMAS AND A SUBSET OF TUMORS DERIVED FROM CELLS WITH LOW RATES OF SELF-RENEWAL

    PubMed Central

    Yan, Hai; Killela, P.J.; Reitman, Z.J.; Jiao, Y.; Bettegowda, C.; Agrawal, N.; Diaz, L.A.; Friedman, A.H.; Friedman, H.; Gallia, G.L.; Giovanella, B.C.; Grollman, A.P.; He, T.C.; He, Y.; Hruban, R.H.; Jallo, G.I.; Mandahl, N.; Meeker, A.K.; Mertens, F.; Netto, G.J.; Rasheed, B.A.; Riggins, G.J.; Rosenquist, T.A.; Schiffman, M.; Shih, IeM; Theodorescu, D.; Torbenson, M.S.; Velculescu, V.E.; Wang, T.L.; Wentzensen, N.; Wood, L.D.; Zhang, M.; Healy, P.; Yang, R.; Diplas, B.; Wang, Z.H.; Greer, P.; Zhu, H.S.; Wang, C.; Carpenter, A.; Herndon, J.E.; McLendon, R.E.; Kinzler, K.W.; Vogelstein, B.; Papadopoulos, N.; Bigner, D.D.

    2014-01-01

    BACKGROUND: Malignant cells must maintain their telomeres, but genetic mechanisms responsible for telomere maintenance in tumors have only recently been discovered. In particular, mutations of the telomere binding proteins alpha thalassemia/mental retardation syndrome X-linked (ATRX) or death-domain associated protein (DAXX) have been shown to underlie a telomere maintenance mechanism not involving telomerase (alternative lengthening of telomeres), and point mutations in the promoter of the telomerase reverse transcriptase (TERT) gene increase telomerase expression and have been shown to occur in melanomas. METHODS: To further define the tumor types in which TERT plays a role, we surveyed 1,230 tumors of 60 different types. We also analyzed the relationship between median overall survival (OS) of patients with IDH1/2 and TERT promoter mutations in a panel of 473 adult gliomas with the hypothesis that genetic signatures capable of distinguishing among several types of gliomas could be established providing clinically relevant information that can serve as an adjunct to histopathological diagnosis. RESULTS: We found that tumors could be divided into types with low and high frequencies of TERT promoter mutations. The nine TERT-high tumor types almost always originated in tissues with relatively low rates of self renewal, including melanomas, liposarcomas, hepatocellular carcinomas, urothelial carcinomas, squamous cell carcinomas of the tongue, medulloblastomas, and subtypes of gliomas. TERT and ATRX mutations were mutually exclusive, suggesting that these two genetic mechanisms confer equivalent selective growth advantages. We found that mutations in the TERT promoter occurred in 74.2% of glioblastomas (GBM), but occurred in a minority of Grade II-III astrocytomas (18.2%). In contrast, IDH1/2 mutations were observed in 78.4% of Grade II-III astrocytomas, but were uncommon in primary GBM. In oligodendrogliomas, TERT promoter and IDH1/2 mutations co-occurred in 79% of cases. Patients whose Grade III-IV gliomas exhibit TERT promoter mutations alone predominately have primary GBMs associated with poor median OS rates (11.5 months). Patients whose gliomas exhibit IDH1/2 mutations alone predominately have astrocytic morphologies and exhibit a median OS of 57 months while patients whose tumors exhibit both TERT promoter and IDH1/2 mutations predominately exhibit oligodendroglial morphologies and exhibit median OS of 125 months. CONCLUSIONS: In addition to their implications for understanding the relationship between telomeres and tumorigenesis, TERT mutations provide a biomarker that may aid in the classification and prognostication of brain tumors. SECONDARY CATEGORY: Tumor Biology.

  13. Solar wind proton density variations that preceded the M6,1 earthquake occurred in New Caledonia on November 10, 2014

    NASA Astrophysics Data System (ADS)

    Cataldi, Gabriele; Cataldi, Daniele; Straser, Valentino

    2015-04-01

    This work analyzed the modulation of the solar wind proton density variation that preceded the M6,1 earthquake occurred in New Caledonia on November 10, 2014 at 10:04:21 UTC. The purpose of the study has been to verify the existence of a correlation between solar activity and the earthquake and for testing a method to be applied in the future also for the prediction of tsunami. The ionic data used to realize the correlation study are represented by: solar wind ion density variation detected by ACE (Advanced Composition Explorer) Satellite, in orbit near the L1 Lagrange point, at 1.5 million of km from Earth, in direction of the Sun. The instrument used to perform the measurement of the solar wind ion density is the Electron, Proton, and Alpha Monitor (EPAM) instrument, equipped on the ACE Satellite. To conduct the study, the authors have taken in consideration the variation of the solar wind protons density that have these characteristics: differential proton flux 1060-1900 keV (p/cm^2-sec-ster-MeV); differential proton flux 761-1220 keV (p/cm^2-sec-ster-MeV); differential proton flux 310-580 keV (p/cm^2-sec-ster-MeV) and differential proton flux 115-195 keV (p/cm^2-sec-ster-MeV). The sample data used to conduct the study refers the period going from 7 to 10 November 2014. The data on the M6,1 earthquake are provided in real time by the USGS (United States Geological Survey). The data analysis revealed that the M6,1 earthquake occurred in New Caledonia on November 10, 2014 at 10:04:21 UTC, was preceded by a solar coronal mass ejection (CME) that reached Earth at 19:31:04 UTC (± 6 hours, ISWA data) on November 9, 2014. The CME event produced an increase of solar wind ion density that preceded the earthquakes of about 14.5 hours.

  14. Earthquake prediction

    SciTech Connect

    Ma, Z.; Fu, Z.; Zhang, Y.; Wang, C.; Zhang, G.; Liu, D.

    1989-01-01

    Mainland China is situated at the eastern edge of the Eurasian seismic system and is the largest intra-continental region of shallow strong earthquakes in the world. Based on nine earthquakes with magnitudes ranging between 7.0 and 7.9, the book provides observational data and discusses successes and failures of earthquake prediction. Derived from individual earthquakes, observations of various phenomena and seismic activities occurring before and after earthquakes, led to the establishment of some general characteristics valid for earthquake prediction.

  15. A pre seismic radio anomaly revealed in the area where the Abruzzo earthquake (M=6.3) occurred on 6 April 2009

    NASA Astrophysics Data System (ADS)

    Biagi, P. F.; Castellana, L.; Maggipinto, T.; Loiacono, D.; Schiavulli, L.; Ligonzo, T.; Fiore, M.; Suciu, E.; Ermini, A.

    2009-09-01

    On 6 April 2009 a strong (Mw=6.3) earthquake occurred in the Abruzzo region (central Italy). Since 1996, the intensity of CLT (f=189 kHz, Sicily, Italy), MCO (f=216 kHz, France) and CZE (f=270 kHz, Czech Republic) broadcast signals has been collected with a ten minutes sampling rate by a receiver operating in a place located about 13 km far from the epicenter. During March 2009, the old receiver was substituted with a new one able to measure, with one minute sampling rate, the intensity of five VLF signals and five LF signals radiated by transmitters located in different zones of Europe. The MCO and CZE transmitters mentioned above are included among them. From 31 March to 1 April the intensity of the MCO radio signal dropped and this drop was observed only in this signal. The possibility that the drop was connected to problems in the transmitter or in the receiver was investigated and excluded. So, the drop indicates a defocusing of the radiated signal. Since no particular meteorological situation along the path transmitter-receiver happened, the defocusing must be related to other causes, and a possibility is presented that it is a precursor of the Abruzzo earthquake.

  16. Hidden earthquakes

    SciTech Connect

    Stein, R.S.; Yeats, R.S.

    1989-06-01

    Seismologists generally look for earthquakes to happen along visible fault lines, e.g., the San Andreas fault. The authors maintain that another source of dangerous quakes has been overlooked: the release of stress along a fault that is hidden under a fold in the earth's crust. The paper describes the differences between an earthquake which occurs on a visible fault and one which occurs under an anticline and warns that Los Angeles greatest earthquake threat may come from a small quake originating under downtown Los Angeles, rather than a larger earthquake which occurs 50 miles away at the San Andreas fault.

  17. A possible scenario for earlier occurrence of the next Nankai earthquake due to triggering by an earthquake at Hyuga-nada, off southwest Japan

    NASA Astrophysics Data System (ADS)

    Hyodo, Mamoru; Hori, Takane; Kaneda, Yoshiyuki

    2016-01-01

    Several recent large-scale earthquakes including the 2011 Tohoku earthquake ( M w 9.0) in northeastern Japan and the 2014 Iquique earthquake ( M w 8.1) in northern Chile were associated with foreshock activities ( M w > 6). The detailed mechanisms between these large earthquakes and the preceding smaller earthquakes are still unknown; however, to plan for disaster mitigation against the anticipated great Nankai Trough earthquakes, in this study, possible scenarios after M w 7-class earthquakes that frequently occur near the focal region of the Nankai Trough are examined through quasi-dynamic modeling of seismic cycles. By assuming that simulated Nankai Trough earthquakes recur as two alternative earthquakes with variations in magnitudes ( M w 8.7-8.4) and recurrence intervals (178-143 years), we systematically examine the effect of the occurrence timing of the M w 7 Hyuga-nada earthquake on the western extension of the source region of Nankai Trough earthquakes on the assumed Nankai Trough seismic cycles. We find that in the latter half of a seismic cycle preceding a large Nankai Trough earthquake, an immature Nankai earthquake tends to be triggered within several years after the occurrence of a Hyuga-nada earthquake, then Tokai (Tonankai) earthquakes occur with maximum time lags of several years. The combined magnitudes of the triggered Nankai and subsequent Tokai (Tonankai) earthquakes become gradually larger with later occurrence of the Hyuga-nada earthquake, while the rupture timings between the Nankai and Tokai (Tonankai) earthquakes become smaller. The triggered occurrence of an immature Nankai Trough earthquake could delay the expected larger Nankai Trough earthquake to the next seismic cycle. Our results indicate that triggering can explain the variety and complexity of historical Nankai Trough earthquakes. Moreover, for the next anticipated event, countermeasures should include the possibility of a triggered occurrence of a Nankai Trough earthquake by an M w 7 Hyuga-nada earthquake.

  18. Subionospheric VLF/LF radio waves propagation characteristics before, during and after the Sofia, Bulgaria Mw=5.6 earthquake occurred on 22 May 2012

    NASA Astrophysics Data System (ADS)

    Moldovan, Iren Adelina; Emilian Toader, Victorin; Nenovski, Petko; Biagi, Pier Francesco; Maggipinto, Tommaso; Septimiu Moldovan, Adrian; Ionescu, Constantin

    2013-04-01

    In 2009, INFREP, a network of VLF (20-60 kHz) and LF (150-300 kHz) radio receivers, was put into operation in Europe having as principal goal, the study of disturbances produced by the earthquakes on the propagation properties of these signals. On May 22nd, 2012 an earthquake with Mw=567 occurred in Bulgaria, near Sofia, inside the "sensitive" area of the INFREP VLF/LF electromagnetic network. The data collected on different frequencies, during April-May 2012 were studied using different methods of analysis: daily correlation methods, spectral approaches and terminator time techniques, in order to find out possible connections between the seismic activity and the subionospheric propagation properties of radio waves. The studies were performed with the help of a specially designed LabVIEW application, which accesses the VLF/LF receiver through internet. This program opens the receiver's web-page and automatically retrieves the list of data files to synchronize the user-side data with the receiver's data. Missing zipped files are also automatically downloaded. The application performs primary, statistical correlation and spectral analysis, appends daily files into monthly and annual files and performs 3D colour-coded maps with graphic representations of VLF and LF signals' intensities versus the minute-of-the-day and the day-of-the-month, facilitating a near real-time observation of VLF and LF electromagnetic waves' propagation. Another feature of the software is the correlation of the daily recorded files for the studied frequencies by overlaying the 24 hours radio activity and taking into account the sunrise and sunset. Data are individually processed (spectral power, correlations, differentiation, filtered using bandpass, lowpass, highpass). JTFA spectrograms (Cone-Shaped Distribution CSD, Gabor, Wavelet, short-time Fourier transform STFT, Wigner-Ville Distribution WVD, Choi-Williams Distribution CWD) are used, too.

  19. Safety and survival in an earthquake

    USGS Publications Warehouse

    U.S. Geological Survey

    1969-01-01

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

  20. Urban Earthquakes - Reducing Building Collapse Through Education

    NASA Astrophysics Data System (ADS)

    Bilham, R.

    2004-12-01

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

  1. Self-similar rupture implied by scaling properties of volcanic earthquakes occurring during the 2004-2008 eruption of Mount St. Helens, Washington

    USGS Publications Warehouse

    Harrington, Rebecca M.; Kwiatek, Grzegorz; Moran, Seth C.

    2015-01-01

    We analyze a group of 6073 low-frequency earthquakes recorded during a week-long temporary deployment of broadband seismometers at distances of less than 3 km from the crater at Mount St. Helens in September of 2006. We estimate the seismic moment (M0) and spectral corner frequency (f0) using a spectral ratio approach for events with a high signal-to-noise (SNR) ratio that have a cross-correlation coefficient of 0.8 or greater with at least five other events. A cluster analysis of cross-correlation values indicates that the group of 421 events meeting the SNR and cross-correlation criteria forms eight event families that exhibit largely self-similar scaling. We estimate the M0 and f0 values of the 421 events and calculate their static stress drop and scaled energy (ER/M0) values. The estimated values suggest self-similar scaling within families, as well as between five of eight families (i.e.,  and  constant). We speculate that differences in scaled energy values for the two families with variable scaling may result from a lack of resolution in the velocity model. The observation of self-similar scaling is the first of its kind for such a large group of low-frequency volcanic tectonic events occurring during a single active dome extrusion eruption.

  2. Self-similar rupture implied by scaling properties of volcanic earthquakes occurring during the 2004-2008 eruption of Mount St. Helens, Washington

    NASA Astrophysics Data System (ADS)

    Harrington, Rebecca M.; Kwiatek, Grzegorz; Moran, Seth C.

    2015-07-01

    We analyze a group of 6073 low-frequency earthquakes recorded during a week-long temporary deployment of broadband seismometers at distances of less than 3 km from the crater at Mount St. Helens in September of 2006. We estimate the seismic moment (M0) and spectral corner frequency (f0) using a spectral ratio approach for events with a high signal-to-noise (SNR) ratio that have a cross-correlation coefficient of 0.8 or greater with at least five other events. A cluster analysis of cross-correlation values indicates that the group of 421 events meeting the SNR and cross-correlation criteria forms eight event families that exhibit largely self-similar scaling. We estimate the M0 and f0 values of the 421 events and calculate their static stress drop and scaled energy (ER/M0) values. The estimated values suggest self-similar scaling within families, as well as between five of eight families (i.e., M0∝f0-3 and ER/M0∝ constant). We speculate that differences in scaled energy values for the two families with variable scaling may result from a lack of resolution in the velocity model. The observation of self-similar scaling is the first of its kind for such a large group of low-frequency volcanic tectonic events occurring during a single active dome extrusion eruption.

  3. Spectral-decomposition techniques for the identification of radon anomalies temporally associated with earthquakes occurring in the UK in 2002 and 2008

    NASA Astrophysics Data System (ADS)

    Crockett, R. G. M.; Gillmore, G. K.

    2010-06-01

    During the second half of 2002, the University of Northampton Radon Research Group operated two continuous hourly-sampling radon detectors 2.25 km apart in the English East Midlands. This period included the Dudley earthquake (ML=5, 22 September 2002). Also, at various periods during 2008 the Group has operated other pairs of continuous hourly-sampling radon detectors similar distances apart in the same region. One such period included the Market Rasen earthquake (ML=5.2, 27 February 2008). Windowed cross-correlation of the paired time-series was used to identify simultaneous short-duration anomalies. In the 2002 data, only two periods of significant cross-correlation were observed, each corresponding temporally to a UK earthquake, one to the Dudley earthquake and the other to a smaller earthquake in the English Channel (ML=3, 26 August 2002). In the 2008 data, cross-correlation initially revealed little evidence of simultaneous short-duration anomalies but cross-correlation of data de-noised and de-trended using Empirical Mode Decomposition (EMD) revealed clear simultaneous short-duration anomalies which correspond temporally to the Market Rasen earthquake.

  4. Earthquake Facts

    MedlinePlus

    ... and have smaller magnitudes than earthquakes on the Earth. It appears they are related to the tidal stresses associated with the varying distance between the Earth and Moon. They also occur at great depth, ...

  5. Threat of an earthquake right under the capital in Japan

    USGS Publications Warehouse

    Rikitake, T.

    1990-01-01

    Tokyo, Japan's capital, has been enjoying a seismically quiet period following the 1923 Kanto earthquake of magnitude 7.9 that killed more than 140,000 people. Such a quiet period seems likely to be a repetition of the 80-year quiescence after the great 1703 Genroku earthquake of magntidue 8.2 that occurred in an epicentral area adjacent to that of the 1923 Kanto earthquake. In 1784, seismic activity immediately under the capital area revived with occasional occurrence of magnitude 6 to 7 shocks. Earthquakes of this class tended to occur more frequently as time went on and they eventually culminated in the 1923 Kanto earthquake. As more than 60 years have passed since the Kanto earthquake, we may well expect another revival of activity immediately under the capital area. 

  6. Non-double-couple mechanism of moderate earthquakes occurred in Lower Siang region of Arunachal Himalaya: Evidence of factors affecting non-DC

    NASA Astrophysics Data System (ADS)

    Kumar, Rohtash; Gupta, S. C.; Kumar, Arjun

    2015-02-01

    Moment Tensor solutions of 104 earthquakes which were observed at local distances in Lower Siang region of Arunachal Himalaya have been estimated using ISOLA code. The magnitude range of analyzed earthquakes lies between 1.8 (Mw) and 5.3 (Mw). Out of 104 earthquakes, only 32 events are having good data. The signal noise ratio of these 32 events is greater than 6 with magnitude greater than 2.5. All possible sources of non-DC such as, noise present in the data, depth of the source, low azimuthal coverage of the event and non-DC as a part of real earthquake source process are examined. The study reveals that non-DC is highly dependent on the source depth as comparatively shallow events shows high CLVD%. The CLVD is also highly affected by the noise present in the data. Another factor is the magnitude of the event. The high magnitude event shows quite high DC%. So the source mechanisms of high magnitude events are double couple (DC).

  7. Significant earthquakes on the Enriquillo fault system, Hispaniola, 1500-2010: Implications for seismic hazard

    USGS Publications Warehouse

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

    2012-01-01

    Historical records indicate frequent seismic activity along the north-east Caribbean plate boundary over the past 500 years, particularly on the island of Hispaniola. We use accounts of historical earthquakes to assign intensities and the intensity assignments for the 2010 Haiti earthquakes to derive an intensity attenuation relation for Hispaniola. The intensity assignments and the attenuation relation are used in a grid search to find source locations and magnitudes that best fit the intensity assignments. Here we describe a sequence of devastating earthquakes on the Enriquillo fault system in the eighteenth century. An intensity magnitude MI 6.6 earthquake in 1701 occurred near the location of the 2010 Haiti earthquake, and the accounts of the shaking in the 1701 earthquake are similar to those of the 2010 earthquake. A series of large earthquakes migrating from east to west started with the 18 October 1751 MI 7.4–7.5 earthquake, probably located near the eastern end of the fault in the Dominican Republic, followed by the 21 November 1751 MI 6.6 earthquake near Port-au-Prince, Haiti, and the 3 June 1770 MI 7.5 earthquake west of the 2010 earthquake rupture. The 2010 Haiti earthquake may mark the beginning of a new cycle of large earthquakes on the Enriquillo fault system after 240 years of seismic quiescence. The entire Enriquillo fault system appears to be seismically active; Haiti and the Dominican Republic should prepare for future devastating earthquakes.

  8. Seismic ACROSS Transmitter Installed at Morimachi above the Subducting Philippine Sea Plate for the Test Monitoring of the Seismogenic Zone of Tokai Earthquake not yet to Occur

    NASA Astrophysics Data System (ADS)

    Kunitomo, T.; Kumazawa, M.; Masuda, T.; Morita, N.; Torii, T.; Ishikawa, Y.; Yoshikawa, S.; Katsumata, A.; Yoshida, Y.

    2008-12-01

    Here we report the first seismic monitoring system in active and constant operation for the wave propagation characteristics in tectonic region just above the subducting plate driving the coming catastrophic earthquakes. Developmental works of such a system (ACROSS; acronym for Accurately Controlled, Routinely Operated, Signal System) have been started in 1994 at Nagoya University and since 1996 also at TGC (Tono Geoscience Center) of JAEA promoted by Hyogoken Nanbu Earthquakes (1995 Jan.17, Mj=7.3). The ACROSS is a technology system including theory of signal and data processing based on the brand new concept of measurement methodology of Green function between a signal source and observation site. The works done for first generation system are reported at IWAM04 and in JAEA report (Kumazawa et al.,2007). The Meteorological Research Institute of JMA has started a project of test monitoring of Tokai area in 2004 in corporation with Shizuoka University to realize the practical use of the seismic ACROSS for earthquake prediction researches. The first target was set to Tokai Earthquake not yet to take place. The seismic ACROSS transmitter was designed so as to be appropriate for the sensitive monitoring of the deep active fault zone on the basis of the previous technology elements accumulated so far. The ground coupler (antenna) is a large steel-reinforced concrete block (over 20m3) installed in the basement rocks in order to preserve the stability. Eccentric moment of the rotary transmitter is 82 kgm at maximum, 10 times larger than that of the first generation. Carrier frequency of FM signal for practical use can be from 3.5 to 15 Hz, and the signal phase is accurately controlled by a motor with vector inverter synchronized with GPS clock with a precision of 10-4 radian or better. By referring to the existing structure model in this area (Iidaka et al., 2003), the site of the transmitting station was chosen at Morimachi so as to be appropriate for detecting the reflected wave from an anticipated fault plane of Tokai Earthquake, the boundary between Eurasian lithosphere and the subducting Philippine Sea Plate. Further several trials of new transmission protocol and also remote control are being made for the transmitter network of the next generation. The whole system appears working well as reported by Yoshida et al. (2008, This meeting).

  9. Earthquake clusters in Corinth Rift

    NASA Astrophysics Data System (ADS)

    Mesimeri, Maria; Papadimitriou, Eleftheria; Karakostas, Vasilios; Tsaklidis, George

    2013-04-01

    Clusters commonly occur as main shock-aftershock (MS-AS) sequences but also as earthquake swarms, which are empirically defined as an increase in seismicity rate above the background rate without a clear triggering main shock earthquake. Earthquake swarms occur in a variety of different environments and might have a diversity of origins, characterized by a high b-value in their magnitude distribution. The Corinth Rift, which was selected as our target area, appears to be the most recent extensional structure, with a likely rate of fault slip of about 1cm/yr and opening of 7mm/yr. High seismic activity accommodates the active deformation with frequent strong (M≥6.0) events and several seismic excitations without a main shock with clearly discriminative magnitude. Identification of earthquake clusters that occurred in this area in last years and investigation of their spatio-temporal distribution is attempted, with the application of known declustering algorithms, aiming to associate their occurrence with certain patterns in seismicity behavior. The earthquake catalog of the National Hellenic Seismological Network is used, and a certain number of clusters were extracted from the dataset, with the MS-AS sequences being distinguished from earthquake swarms. Spatio-temporal properties of each subset were analyzed in detail, after determining the respective completeness magnitude. 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 statistical physics - Application to the geodynamic system of the Hellenic Arc, SEISMO FEAR HELLARC".

  10. STUDY ON EARTHQUAKE DAMAGE IN DUCTILE IRON PIPE JOINT

    NASA Astrophysics Data System (ADS)

    Kumaki, Yoshihiro; Miyajima, Masakatsu

    In recent year, most of water pipe damages caused by earthquakes have been reported by pull out at joint. Ductile iron pipe are classified as mechanical type for earthquake-proof or non-earthquake-proof joint and slip-on type for non-e-proof joint. The earthquake proof joint never been damaged in the past earthquakes but the damage for another types of joint occurred frequently. Since the type of joint depends on the manufaction age and pipe diameter. Therefore, it could be estimated the relation between the damage rate and joint type. This paper focused on this issue. The resistance force against pull out at joint was clarified by the experiments and the results are discussed. Finally the earthquake adaptability for the different joint types is proposed.

  11. Tectonic earthquakes of anthropogenic origin

    NASA Astrophysics Data System (ADS)

    Adushkin, V. V.

    2016-03-01

    The enhancement of seismicity induced by industrial activity in Russia in the conditions of present-day anthropization is noted. In particular, the growth in the intensity and number of strong tectonic earthquakes with magnitudes M ≥ 3 (seismic energy 109 J) due to human activity is revealed. These man-made tectonic earthquakes have started to occur in the regions of the East European Platform which were previously aseismic. The development of such seismicity is noted in the areas of intense long-term mineral extraction due to the increasing production depth and extended mining and production. The mechanisms and generation conditions of man-made tectonic earthquakes in the anthropogenically disturbed medium with the changed geodynamical and fluid regime is discussed. The source zones of these shallow-focus tectonic earthquakes of anthropogenic origin are formed in the setting of stress state rearrangement under anthropogenic loading both near these zones and at a significant distance from them. This distance is determined by the tectonic structure of the rock mass and the character of its energy saturation, in particular, by the level of the formation pressure or pore pressure. These earthquakes occur at any time of the day, have a triggered character, and are frequently accompanied by catastrophic phenomena in the underground mines and on the surface due to the closeness to the source zones.

  12. Winnetka deformation zone: Surface expression of coactive slip on a blind fault during the Northridge earthquake sequence, California. Evidence that coactive faulting occurred in the Canoga Park, Winnetka, and Northridge areas during the 17 January 1994, Northridge, California earthquake

    SciTech Connect

    Cruikshank, K.M.; Johnson, A.M.; Fleming, R.W.; Jones, R.L.

    1996-12-31

    Measurements of normalized length changes of streets over an area of 9 km{sup 2} in San Fernando Valley of Los Angeles, California, define a distinctive strain pattern that may well reflect blind faulting during the 1994 Northridge earthquake. Strain magnitudes are about 3 {times} 10{sup {minus}4}, locally 10{sup {minus}3}. They define a deformation zone trending diagonally from near Canoga Park in the southwest, through Winnetka, to near Northridge in the northeast. The deformation zone is about 4.5 km long and 1 km wide. The northwestern two-thirds of the zone is a belt of extension of streets, and the southeastern one-third is a belt of shortening of streets. On the northwest and southeast sides of the deformation zone the magnitude of the strains is too small to measure, less than 10{sup {minus}4}. Complete states of strain measured in the northeastern half of the deformation zone show that the directions of principal strains are parallel and normal to the walls of the zone, so the zone is not a strike-slip zone. The magnitudes of strains measured in the northeastern part of the Winnetka area were large enough to fracture concrete and soils, and the area of larger strains correlates with the area of greater damage to such roads and sidewalks. All parts of the pattern suggest a blind fault at depth, most likely a reverse fault dipping northwest but possibly a normal fault dipping southeast. The magnitudes of the strains in the Winnetka area are consistent with the strains produced at the ground surface by a blind fault plane extending to depth on the order of 2 km and a net slip on the order of 1 m, within a distance of about 100 to 500 m of the ground surface. The pattern of damage in the San Fernando Valley suggests a fault segment much longer than the 4.5 km defined by survey data in the Winnetka area. The blind fault segment may extend several kilometers in both directions beyond the Winnetka area. This study of the Winnetka area further supports observations that a large earthquake sequence can include rupture along both a main fault and nearby faults with quite different senses of slip. Faults near the main fault that approach the ground surface or cut the surface in an area have the potential of moving coactively in a major earthquake. Movement on such faults is associated with significant damage during an earthquake. The fault that produced the main Northridge shock and the faults that moved coactively in the Northridge area probably are parts of a large structure. Such interrelationships may be key to understanding earthquakes and damage caused by tectonism.

  13. Mapping of earthquakes vulnerability area in Papua

    NASA Astrophysics Data System (ADS)

    Muhammad Fawzy Ismullah, M.; Massinai, Muh. Altin

    2016-05-01

    Geohazard is a geological occurrence which may lead to a huge loss for human. A mitigation of these natural disasters is one important thing to be done properly in order to reduce the risks. One of the natural disasters that frequently occurs in the Papua Province is the earthquake. This study applies the principle of Geospatial and its application for mapping the earthquake-prone area in the Papua region. It uses earthquake data, which is recorded for 36 years (1973-2009), fault location map, and ground acceleration map of the area. The earthquakes and fault map are rearranged into an earthquake density map, as well as an earthquake depth density map and fault density map. The overlaid data of these three maps onto ground acceleration map are then (compiled) to obtain an earthquake unit map. Some districts area, such as Sarmi, Nabire, and Dogiyai, are identified by a high vulnerability index. In the other hand, Waropen, Puncak, Merauke, Asmat, Mappi, and Bouven Digoel area shows lower index. Finally, the vulnerability index in other places is detected as moderate.

  14. Poly-A binding protein-1 localization to a subset of TDP-43 inclusions in amyotrophic lateral sclerosis occurs more frequently in patients harboring an expansion in C9orf72.

    PubMed

    McGurk, Leeanne; Lee, Virginia M; Trojanowksi, John Q; Van Deerlin, Vivianna M; Lee, Edward B; Bonini, Nancy M

    2014-09-01

    Amyotrophic lateral sclerosis (ALS) is an adult-onset motor neuron disease in which the loss of spinal cord motor neurons leads to paralysis and death within a few years of clinical disease onset. In almost all cases of ALS, transactive response DNA binding protein of 43 kDa (TDP-43) forms cytoplasmic neuronal inclusions. A second causative gene for a subset of ALS is fused in sarcoma, an RNA binding protein that also forms cytoplasmic inclusions in spinal cord motor neurons. Poly-A binding protein-1 (PABP-1) is a marker of stress granules (i.e. accumulations of proteins and RNA indicative of translational arrest in cells under stress). We report on the colocalization of PABP-1 to both TDP-43 and fused-in-sarcoma inclusions in 4 patient cohorts: ALS without a mutation, ALS with an intermediate polyglutamine repeat expansion in ATXN2, ALS with a GGGGCC hexanucleotide repeat expansion in C9orf72, and ALS with basophilic inclusion body disease. Notably, PABP-1 colocalization to TDP-43 was twice as frequent in ALS with C9orf72 expansions compared to ALS with no mutation. This study highlights PABP-1 as a protein that is important to the pathology of ALS and indicates that the proteomic profile of TDP-43 inclusions in ALS may differ depending on the causative genetic mutation. PMID:25111021

  15. Tracking Earthquake Cascades

    NASA Astrophysics Data System (ADS)

    Jordan, T. H.

    2011-12-01

    In assessing their risk to society, earthquakes are best characterized as cascades that can propagate from the natural environment into the socio-economic (built) environment. Strong earthquakes rarely occur as isolated events; they usually cluster in foreshock-mainshock-aftershock sequences, seismic swarms, and extended sequences of large earthquakes that propagate along major fault systems. These cascades are regulated by stress-mediated interactions among faults driven by tectonic loading. Within these cascades, each large event can itself cause a chain reaction in which the primary effects of faulting and ground shaking induce secondary effects, including tsunami, landslides, liquefaction, and set off destructive processes within the built environment, such as fires and radiation leakage from nuclear plants. Recent earthquakes have demonstrated how the socio-economic effects of large earthquakes can reverberate for many years. To reduce earthquake risk and improve the resiliency of communities to earthquake damage, society depends on five geotechnologies for tracking earthquake cascades: long-term probabilistic seismic hazard analysis (PSHA), short-term (operational) earthquake forecasting, earthquake early warning, tsunami warning, and the rapid production of post-event information for response and recovery (see figure). In this presentation, I describe how recent advances in earthquake system science are leading to improvements in this geotechnology pipeline. In particular, I will highlight the role of earthquake simulations in predicting strong ground motions and their secondary effects before and during earthquake cascades

  16. Deep earthquakes

    SciTech Connect

    Frohlich, C.

    1989-01-01

    Earthquakes are often recorded at depths as great as 650 kilometers or more. These deep events mark regions where plates of the earth's surface are consumed in the mantle. But the earthquakes themselves present a conundrum: the high pressures and temperatures at such depths should keep rock from fracturing suddenly and generating a tremor. This paper reviews the research on this problem. Almost all deep earthquakes conform to the pattern described by Wadati, namely, they generally occur at the edge of a deep ocean and define an inclined zone extending from near the surface to a depth of 600 kilometers of more, known as the Wadati-Benioff zone. Several scenarios are described that were proposed to explain the fracturing and slipping of rocks at this depth.

  17. A 2000-year record of migrating earthquakes in North China: Implications for earthquake hazards in continental interiors

    NASA Astrophysics Data System (ADS)

    Liu, Mian; Stein, Seth; Wang, Hui

    2010-05-01

    Plate tectonic theory provides a good sense of where to expect future large earthquakes on plate boundaries, and of the average time between them. However, no comparable model applies in continental interiors, where damaging earthquakes often pop up in unexpected places. This is well illustrated by the 2000-year record of earthquakes in North China, where large earthquakes are frequent and have migrated between fault systems. No large (M>7) events repeated on the same fault segment during this period. Paleoseismic records show episodic large earthquakes with long gaps in between, as have been reported in other mid-continents. We propose that the spatial migration is intrinsic to mid-continental earthquakes. Using a simple conceptual model, we show that in continental interiors slow tectonic loading is accommodated collectively by a complex system of interacting faults. Failure of one fault affects the entire system, and large earthquakes may shut off one fault and activate another. These processes are fundamentally different from those at plate boundaries where earthquakes are concentrated along the plate boundary faults, and steady-state relative plate motion loads the boundary faults rapidly at constant rates so earthquakes are quasi-periodic. The spatial migration and episodic occurrence of mid-continental earthquakes, and their long aftershock sequences that can extend for hundreds of years, explain why in continental interiors past seismicity can be poor indicators of the sites of future large earthquakes. Consequently, seismic hazard assessment based on the assumption of quasi-periodic earthquakes may fail, as illustrated by the unexpected 2008 Wenchuan earthquake that occurred on a fault that showed little seismicity in the past millennium.

  18. Upper-Plate Earthquake Swarms Remotely Triggered by the 2012 Mw-7.6 Nicoya Earthquake, Costa Rica

    NASA Astrophysics Data System (ADS)

    Linkimer, L.; Arroyo, I. G.; Montero Pohly, W. K.; Rojas, W.

    2013-05-01

    Remotely triggered seismicity that takes place at distances greater than 1-2 fault lengths appears to be a frequent phenomenon after large earthquakes, including damaging upper-plate 5.0-to-6.0 magnitude earthquakes in Costa Rica after the large (Mw > 7.0) inter-plate earthquakes in 1983, 1990, and 1991. On September 5, 2012, an inter-plate 7.6-Mw earthquake struck the Nicoya Peninsula, triggering upper-plate seismicity in the interior of Costa Rica. In this study, we analyze the largest earthquake swarms that took place during the first five months after the Nicoya earthquake. These swarms occurred at distances of 200 to 300 km from the Nicoya source region in three different tectonic settings: the Calero Island near the Costa Rica-Nicaragua border in the backarc Caribbean region, the Cartago area in the central part of Costa Rica near the active volcanic arc, and the San Vito area in the Costa Rica-Panama border region, at the southern flank of the Talamanca Cordillera, an inactive portion of the magmatic arc. The Calero swarm with 64 2.0-to-4.2 Mw earthquakes took place from September 22 to October 9, 2012. The earthquake pattern suggests a smaller-scale fault as a possible source even though this swarm is located along the inland projection of the Hess Escarpment. The Cartago swarm with 284 2.0-to-3.7 Mw earthquakes occurred from September 5 to October 5, 2012. The location and left-lateral solution of the largest event focal mechanism suggest that the Aguacaliente fault, which caused the deadliest earthquake in Costa Rican history on May 4, 1910 (Ms 6.4), is the source of some of this triggered seismicity. The San Vito earthquake swarm with 30 2.0-to-4.5 Mw earthquakes occurred between December 9, 2012 and January 28, 2013. These earthquakes occurred in the vicinity of the San Vito and Agua Buena faults, which are located along the inland projection of the Panama Fracture Zone. Documenting remotely triggered earthquakes may provide us with insight into the physics of the earthquake cycle, and may greatly improve seismic hazards assessment by illuminating active structures within the interior of Costa Rica and by pointing to where the next earthquake might be located.

  19. Earthquake history of Oklahoma

    USGS Publications Warehouse

    von Hake, C. A.

    1976-01-01

    The strongest and most widely felt earthquake in Oklahoma occured on April 9, 1952. The intensity VII (Modified Mercalli Scale) tremor was felt over 362,000 sqaure kilometres. A second intensity VII earthquake, felt over a very small area, occurred in October 1956. In addition, 15 other shocks, intensity V or VI, have originated within Oklahoma. 

  20. Earthquake Prediction and Forecasting

    NASA Astrophysics Data System (ADS)

    Jackson, David D.

    Prospects for earthquake prediction and forecasting, and even their definitions, are actively debated. Here, "forecasting" means estimating the future earthquake rate as a function of location, time, and magnitude. Forecasting becomes "prediction" when we identify special conditions that make the immediate probability much higher than usual and high enough to justify exceptional action. Proposed precursors run from aeronomy to zoology, but no identified phenomenon consistently precedes earthquakes. The reported prediction of the 1975 Haicheng, China earthquake is often proclaimed as the most successful, but the success is questionable. An earthquake predicted to occur near Parkfield, California in 19885 years has not happened. Why is prediction so hard? Earthquakes start in a tiny volume deep within an opaque medium; we do not know their boundary conditions, initial conditions, or material properties well; and earthquake precursors, if any, hide amongst unrelated anomalies. Earthquakes cluster in space and time, and following a quake earthquake probability spikes. Aftershocks illustrate this clustering, and later earthquakes may even surpass earlier ones in size. However, the main shock in a cluster usually comes first and causes the most damage. Specific models help reveal the physics and allow intelligent disaster response. Modeling stresses from past earthquakes may improve forecasts, but this approach has not yet been validated prospectively. Reliable prediction of individual quakes is not realistic in the foreseeable future, but probabilistic forecasting provides valuable information for reducing risk. Recent studies are also leading to exciting discoveries about earthquakes.

  1. Toxic Peptides Occur Frequently in Pergid and Argid Sawfly Larvae

    PubMed Central

    Boevé, Jean-Luc; Rozenberg, Raoul; Shinohara, Akihiko; Schmidt, Stefan

    2014-01-01

    Toxic peptides containing D-amino acids are reported from the larvae of sawfly species. The compounds are suspected to constitute environmental contaminants, as they have killed livestock grazing in areas with congregations of such larvae, and related larval extracts are deleterious to ants. Previously, two octapeptides (both called lophyrotomin) and three heptapeptides (pergidin, 4-valinepergidin and dephosphorylated pergidin) were identified from three species in the family Pergidae and one in Argidae. Here, the hypothesis of widespread occurrence of these peptides among sawflies was tested by LC-MS analyses of single larvae from eight pergid and 28 argid species, plus nine outgroup species. At least two of the five peptides were detected in most sawfly species, whereas none in any outgroup taxon. Wherever peptides were detected, they were present in each examined specimen of the respective species. Some species show high peptide concentrations, reaching up to 0.6% fresh weight of 4-valinepergidin (1.75 mg/larva) in the pergid Pterygophorus nr turneri. All analyzed pergids in the subfamily Pterygophorinae contained pergidin and 4-valinepergidin, all argids in Arginae contained pergidin and one of the two lophyrotomins, whereas none of the peptides was detected in any Perginae pergid or Sterictiphorinae argid (except in Schizocerella pilicornis, which contained pergidin). Three of the four sawfly species that were previously known to contain toxins were reanalyzed here, resulting in several, often strong, quantitative and qualitative differences in the chemical profiles. The most probable ecological role of the peptides is defense against natural enemies; the poisoning of livestock is an epiphenomenon. PMID:25121515

  2. Maximum Earthquake Magnitude Assessments by Japanese Government Committees (Invited)

    NASA Astrophysics Data System (ADS)

    Satake, K.

    2013-12-01

    The 2011 Tohoku earthquake (M 9.0) was the largest earthquake in Japanese history and such a gigantic earthquake was not foreseen around Japan. After the 2011 disaster, various government committees in Japan have discussed and assessed the maximum credible earthquake size around Japan, but their values vary without definite consensus. I will review them with earthquakes along the Nankai Trough as an example. The Central Disaster Management Council, under Cabinet Office, set up a policy for the future tsunami disaster mitigation. The possible future tsunamis are classified into two levels: L1 and L2. The L2 tsunamis are the largest possible tsunamis with low frequency of occurrence, for which saving people's lives is the first priority with soft measures such as tsunami hazard maps, evacuation facilities or disaster education. The L1 tsunamis are expected to occur more frequently, typically once in a few decades, for which hard countermeasures such as breakwater must be prepared. The assessments of L1 and L2 events are left to local governments. The CDMC also assigned M 9.1 as the maximum size of earthquake along the Nankai trough, then computed the ground shaking and tsunami inundation for several scenario earthquakes. The estimated loss is about ten times the 2011 disaster, with maximum casualties of 320,000 and economic loss of 2 trillion dollars. The Headquarters of Earthquake Research Promotion, under MEXT, was set up after the 1995 Kobe earthquake and has made long-term forecast of large earthquakes and published national seismic hazard maps. The future probability of earthquake occurrence, for example in the next 30 years, was calculated from the past data of large earthquakes, on the basis of characteristic earthquake model. The HERP recently revised the long-term forecast of Naknai trough earthquake; while the 30 year probability (60 - 70 %) is similar to the previous estimate, they noted the size can be M 8 to 9, considering the variability of past earthquakes. The Nuclear Regulation Authority, established in 2012, makes independent decisions based on the latest scientific knowledge. They assigned maximum credible earthquake magnitude of 9.6 for Nankai an Ryukyu troughs, 9.6 for Kuirl-Japan trench, and 9.2 for Izu-Bonin trench.

  3. Earthquakes and Schools

    ERIC Educational Resources Information Center

    National Clearinghouse for Educational Facilities, 2008

    2008-01-01

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

  4. Disaster triggers disaster: Earthquake triggering by tropical cyclones

    NASA Astrophysics Data System (ADS)

    Wdowinski, S.; Tsukanov, I.

    2011-12-01

    Three recent devastating earthquakes, the 1999 M=7.6 Chi-Chi (Taiwan), 2010 M=7.0 Leogane (Haiti), 2010 M=6.4 Kaohsiung (Taiwan), and additional three moderate size earthquakes (6occurred in tropical mountainous areas shortly after very wet tropical cyclones (hurricane or typhoon) hit the very same area. The most familiar example is Haiti, which was hit during the late summer of 2008 by two hurricanes and two tropical storms (Fay, Gustav, Hanna and Ike) within 25 days. A year an a half after this very wet hurricane season, the 2010 Leogane earthquake occurred in the mountainous Haiti's southern peninsula and caused the death of more than 300,000 people. The other cases are from Taiwan, which is characterized by a high seismicity level and frequent typhoon landfall. The three wettest typhoons in Taiwan's past 50 years were Morakot (in 2009, with 2885 mm or rain), Flossie (1969, 2162 mm) and Herb (1996, 1987 mm)[Lin et al., 2010]. Each of this three very wet storms was followed by one or two main-shock M>6 earthquake that occurred in the central mountainous area of Taiwan within three years after the typhoon. The 2009 Morakot typhoon was followed by 2009 M=6.2 Nantou and 2010 M=6.4 Kaohsiung earthquakes; the 1969 Flossie typhoon was followed by an M=6.3 earthquake in 1972; and the 1996 Herb typhoon by the 1998 M=6.2 Rueyli and 1999 M=7.6 Chi-Chi earthquakes. The earthquake catalog of Taiwan lists only two other M>6 main-shocks that occurred in Taiwan's central mountainous belt, one of them was in 1964 only four months after the wet Typhoon Gloria poured heavy rain in the same area. We suggest that the close proximity in time and space between wet tropical cyclones and earthquakes reflects a physical link between the two hazard types in which these earthquakes were triggered by rapid erosion induced by tropical cyclone's heavy rain. Based on remote sensing observations, meshfree finite element modeling, and Coulomb failure stress analysis, we show that the erosion induced by very wet cyclones increased the failure stresses at the hypocenters' depth by 300-1500 Pa, which ultimately triggered these earthquakes. Our findings are supported by a statistical analysis indicating a very low probability (1-5%) for a random earthquake occurrence process to form the observed typhoon-earthquake temporal distribution.

  5. Earthquake swarms on Mount Erebus, Antarctica

    NASA Astrophysics Data System (ADS)

    Kaminuma, Katsutada; Baba, Megumi; Ueki, Sadato

    1986-12-01

    Mount Erebus (3794 m), located on Ross Island in McMurdo Sound, is one of the few active volcanoes in Antartica. A high-sensitivity seismic network has been operated by Japanese and US parties on and around the Volcano since December, 1980. The results of these observations show two kinds of seismic activity on Ross Island: activity concentrated near the summit of Mount Erebus associated with Strombolian eruptions, and micro-earthquake activity spread through Mount Erebus and the surrounding area. Seismicity on Mount Erebus has been quite high, usually exceeding 20 volcanic earthquakes per day. They frequently occur in swarms with daily counts exceeding 100 events. Sixteen earthquake swarms with more than 250 events per day were recorded by the seismic network during the three year period 1982-1984, and three notable earthquake swarms out of the sixteen were recognized, in October, 1982 (named 82-C), March-April, 1984 (84-B) and July, 1984 (84-F). Swarms 84-B and 84-F have a large total number of earthquakes and large Ishimoto-Iida's "m"; hence these two swarms are presumed to constitute on one of the precursor phenomena to the new eruption, which took place on 13 September, 1984, and lasted a few months.

  6. Earthquake history of Wisconsin

    USGS Publications Warehouse

    von Hake, C. A.

    1978-01-01

    Only one earthquake of intensity V on the Modified Mercalli Intensity Scale (MM) or greater has occurred within Wisconsin during historic times. Some shocks originating in Illinois, Michigan, Missouri, Ohio, and Canada have been felt. 

  7. Earthquake history of Tennessee

    USGS Publications Warehouse

    von Hake, C. A.

    1977-01-01

     The western part of the State was shaken strongly by the New Madrid, Mo., earthquakes of 1811-12 and by earthquakes in 1843 and 1895. The area has also experienced minor shocks. Additional activity has occurred in the eastern part of the State, near the North Carolina border. Forty shocks of intensity V (Modified Mercalli scale) or greater have been cataloged as occurring within the State. Many other earthquakes centered in bordering States have affected points in Tennessee. The following summary covers only hose shocks of intensity VI or greater. 

  8. Defeating Earthquakes

    NASA Astrophysics Data System (ADS)

    Stein, R. S.

    2012-12-01

    The 2004 M=9.2 Sumatra earthquake claimed what seemed an unfathomable 228,000 lives, although because of its size, we could at least assure ourselves that it was an extremely rare event. But in the short space of 8 years, the Sumatra quake no longer looks like an anomaly, and it is no longer even the worst disaster of the Century: 80,000 deaths in the 2005 M=7.6 Pakistan quake; 88,000 deaths in the 2008 M=7.9 Wenchuan, China quake; 316,000 deaths in the M=7.0 Haiti, quake. In each case, poor design and construction were unable to withstand the ferocity of the shaken earth. And this was compounded by inadequate rescue, medical care, and shelter. How could the toll continue to mount despite the advances in our understanding of quake risk? The world's population is flowing into megacities, and many of these migration magnets lie astride the plate boundaries. Caught between these opposing demographic and seismic forces are 50 cities of at least 3 million people threatened by large earthquakes, the targets of chance. What we know for certain is that no one will take protective measures unless they are convinced they are at risk. Furnishing that knowledge is the animating principle of the Global Earthquake Model, launched in 2009. At the very least, everyone should be able to learn what his or her risk is. At the very least, our community owes the world an estimate of that risk. So, first and foremost, GEM seeks to raise quake risk awareness. We have no illusions that maps or models raise awareness; instead, earthquakes do. But when a quake strikes, people need a credible place to go to answer the question, how vulnerable am I, and what can I do about it? The Global Earthquake Model is being built with GEM's new open source engine, OpenQuake. GEM is also assembling the global data sets without which we will never improve our understanding of where, how large, and how frequently earthquakes will strike, what impacts they will have, and how those impacts can be lessened by our actions. Using these global datasets will help to make the model as uniform as possible. The model must be built by scientists in the affected countries with GEM's support, augmented by their insights and data. The model will launch in 2014; to succeed it must be open, international, independent, and continuously tested. But the mission of GEM is not just the likelihood of ground shaking, but also gaging the economic and social consequences of earthquakes, which greatly amplify the losses. For example, should the municipality of Istanbul retrofit schools, or increase its insurance reserves and recovery capacity? Should a homeowner in a high-risk area move or strengthen her building? This is why GEM is a public-private partnership. GEM's fourteen public sponsors and eight non-governmental organization members are standing for the developing world. To extend GEM into the financial world, we draw upon the expertise of companies. GEM's ten private sponsors have endorsed the acquisition of public knowledge over private gain. In a competitive world, this is a courageous act. GEM is but one link in a chain of preparedness: from earth science and engineering research, through groups like GEM, to mitigation, retrofit or relocate decisions, building codes and insurance, and finally to prepared hospitals, schools, and homes. But it is a link that our community can make strong.

  9. Millenary Mw > 9.0 earthquakes required by geodetic strain in the Himalaya

    NASA Astrophysics Data System (ADS)

    Stevens, V. L.; Avouac, J.-P.

    2016-02-01

    The Himalayan arc produced the largest known continental earthquake, the Mw ≈ 8.7 Assam earthquake of 1950, but how frequently and where else in the Himalaya such large-magnitude earthquakes occur is not known. Paleoseismic evidence for coseismic ruptures at the front of the Himalaya with 15 to 30 m of slip suggests even larger events in medieval times, but this inference is debated. Here we estimate the frequency and magnitude of the largest earthquake in the Himalaya needed so that the moment released by seismicity balances the deficit of moment derived from measurements of geodetic strain. Assuming one third of the moment buildup is released aseismically and the earthquakes roughly follow a Gutenberg-Richter distribution, we find that Mw > 9.0 events are needed with a confidence level of at least 60% and must return approximately once per 800 years on average.

  10. Pliocene to Recent Tectonic Activity of the Reşadiye Peninsula and the Relationship Between the Recent Earthquakes Occurred in the Gulf of Gökova: Preliminary Results.

    NASA Astrophysics Data System (ADS)

    Kahraman, Burcu; Özsayın, Erman; Üner, Serkan; Dirik, Kadir

    2013-04-01

    The E-W trending Reşadiye peninsula located at the southwestern part of the Anatolian Plate is an important horst developed between Gökova and Hisarönü Grabens. NW-trending the Datça Graben is the prominent structure comprising on the Reşadiye peninsula and records the significant fingerprints of palaeogeographical and kinematical characteristics from Pliocene to recent. The Datça Graben is controlled by NW-trending the Karaköy fault in the south and E-W trending the Kızlan fault in the north. Basement rocks of the graben are composed of ophiolitic rocks of the Lycian Nappes and Jurassic marine carbonates. The basinfill initiates with Early Pliocene Kızılaǧaç formation consisting conglomerates and continues with transgressive sequence (Yıldırımlı formation) composed of conglomerates, sandstones and marls with ignimbrite intercalations. Late Pliocene age was attributed to this formation based on the gastropoda and pelecypoda fauna according to previous studies. These units are unconformably overlain by Quaternary Karaköy formation consisting red blocky conglomerates. Pyroclastics of Quaternary age (161 ka) cover the older units. Alluvium, alluvial fan deposits and terrace deposits are the youngest units of the study area. To state the tectonic evolution of the Datça Graben, bedding planes and palaeostress analysis of the fault-slip data were used. The palaeostress analyses of the Kızlan fault clearly represent N-S tensional stress regime with pure normal fault characteristics. Due to the thick colluvium and alluvial fans, any fault-slip data were collected from the Karaköy fault. Considering the same stress regime is viable for the southwestern margin of the graben, fault planes ought to have normal fault characteristics with minor strike-slip component. SW-dipping bedding planes and SW-bearing palaeocurrent measurements show that Karaköy fault occurred before the Kızlan fault and the basin was first formed as a half-graben during Early Pliocene and continued till Late Pliocene. As the Kızlan fault juxtaposes the Kızılaǧaç and Yıldırımlı formations, Late Pliocene age is attributed to the fault. Focal mechanism solutions of recent earthquakes occurred in the Gökova Bay show N-S extension which is compatible with the palaeostress analyses of the Kızlan fault. This situation represents the ongoing activity along the northern margin of the Datça Graben.

  11. History of significant earthquakes in the Parkfield area

    USGS Publications Warehouse

    Bakun, W.H.

    1988-01-01

    Seismicity on the San Andreas fault near Parkfield occurs in a tectonic section that differs markedly from neighboring sections along the San Andreas to the northwest and to the southeast. Northwest of the Parkfield section, small shocks (magnitudes of less than 4) do occur frequently, but San Andreas movement occurs predominantly as aseismic fault creep; shocks of magnitude 6 and larger are unknown, and little, if any, strain is accumulating. In contrast, very few small earthquakes and no aseismic slip have been observed on the adjacent section to the southeast, the Cholame section, which is considered to be locked, in as much as it apparently ruptures exclusively in large earthquakes (magnitudes greater than 7), most recently during the great Fort Tejon earthquake of 1857. The Parkfield section is thus a transition zone between two sections having different modes of fault failure. In fact, the regularity of significant earthquakes at Parkfield since 1857 may be due to the nearly constant slip rate pattern on the adjoining fault sections. Until the magnitude 6.7 Coalinga earthquake on May 2, 1983, 40 kilmoeters northeast of Parkfield, the Parkfield section had been relatively free of stress changes due to nearby shocks; the effect of the Coalinga shock on the timing of the next Parkfield shock is not known. 

  12. Earthquake history of Wyoming

    USGS Publications Warehouse

    von Hake, C. A.

    1978-01-01

    Forty-five earthquakes of moderate intensity (V or greater) on the Modified Mercalli Intensity Scale (MM) and extent have originated in Wyoming from 1894 to 1976. Many shocks have occurred in Yellowstone National Park, including an intensity VII event in June 1975. the 1959 Hebgen Lake, Mont., earthquake, centered just west of the park, was felt (MM VII) in northwestern Wyoming. Many aftershocks from this earthquake were reported in Yellowstone Park (MM V-VI) through December 1959, and numerous shocks of lesser intensities continued through 1963. 

  13. Landslides caused by earthquakes.

    USGS Publications Warehouse

    Keefer, D.K.

    1984-01-01

    Data from 40 historical world-wide earthquakes were studied to determine the characteristics, geologic environments, and hazards of landslides caused by seismic events. This sample was supplemented with intensity data from several hundred US earthquakes to study relations between landslide distribution and seismic parameters. Correlations between magnitude (M) and landslide distribution show that the maximum area likely to be affected by landslides in a seismic event increases from approximately 0 at M = 4.0 to 500 000 km2 at M = 9.2. Each type of earthquake-induced landslide occurs in a particular suite of geologic environments. -from Author

  14. Earthquake history of Nebraska

    USGS Publications Warehouse

    von Hake, C. A.

    1974-01-01

    Nebraska is in a region of moderate seismicity occasionally punctuated by rather strong earthquakes. Most of the State is seismic risk zone 1, with a small part in the southeast corner in risk zone 2. the first significant earthquake felt in Nebraska occurred in 1867, the year that statehood was achieved. the tremor occurred on April 24, 1867, and was apparently centered near Lawrence, Kansas. It affected an area estimated at 780,000 km2 including much of Nebraska. Since 1867, at least seven earthquakes of intensity V or greater have originated within Nebraska's boundaries. Several strong earthquakes centered in neighboring States have also been felt over limited portions of Nebraska. None of these caused damage. 

  15. Volcanic earthquake swarms at Mt. Erebus, Antarctica

    NASA Astrophysics Data System (ADS)

    Kaminuma, Katsutada; Ueki, Sadato; Juergen, Kienle

    1985-04-01

    Mount Erebus is an active volcano in Antarctica located on Ross Island. A convecting lava lake occupies the summit crater of Mt. Erebus. Since December 1980 the seismic activity of Mt. Erebus has been continuously monitored using a radio-telemetered network of six seismic stations. The seismic activity observed by the Ross Island network during the 1982-1983 field season shows that: (1)Strombolian eruptions occur frequently at the Erebus summit lava lake at rates of 2-5 per day; (2)centrally located earthquakes map out a nearly vertical, narrow conduit system beneath the lava lake; (3)there are other source regions of seismicity on Ross Island, well removed from Mt. Erebus proper. An intense earthquake swarm recorded in October 1982 near Abbott Peak, 10 km northwest of the summit of Mt. Erebus, and volcanic tremor accompanying the swarm, may have been associated with new dike emplacement at depth.

  16. 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 here are caused by the stress accumulation due to aseismic slip outside asperity. We consider that a spatial complementary distribution between similar earthquakes in aftershocks and asperity is a characteristic of inland earthquakes. Acknowledgements: We thank the group for the aftershock observations of the 2007 Noto Hanto Earthquake, ERI, Univ. of Tokyo, DPRI, Kyoto Univ., JMA, and NIED for providing the waveform data of aftershocks of the 2007 Noto Hanto Earthquake. We thank the group for the dense aftershock observations of the 2000 Western Tottori Earthquake for providing the waveform data of aftershocks of the 2000 Western Tottori Earthquake. We are grateful to Takashi Iwata, Haruko Sekiguchi, Haruo Horikawa and Manabu Hashimoto for providing their result.

  17. Hidden Earthquakes.

    ERIC Educational Resources Information Center

    Stein, Ross S.; Yeats, Robert S.

    1989-01-01

    Points out that large earthquakes can take place not only on faults that cut the earth's surface but also on blind faults under folded terrain. Describes four examples of fold earthquakes. Discusses the fold earthquakes using several diagrams and pictures. (YP)

  18. Upper-Plate Earthquake Swarms Remotely Triggered by the 2012 Mw-7.6 Nicoya Earthquake, Costa Rica

    NASA Astrophysics Data System (ADS)

    Linkimer, L.; Arroyo, I. G.; Montero Pohly, W. K.; Lücke, O. H.

    2013-12-01

    Remotely triggered seismicity that takes place at distances greater than 1-2 fault lengths appears to be a frequent phenomenon after large earthquakes, including damaging upper-plate 5.0-to-6.0 magnitude earthquakes in Costa Rica after the large (Mw greater than 7.0) inter-plate earthquakes in 1941, 1950, 1983, 1990, and 1991. On 5 of September 2012, an inter-plate 7.6-Mw earthquake struck the Nicoya Peninsula, triggering upper-plate seismicity in the interior of Costa Rica again. The number of upper plate-earthquakes outside the Nicoya source region that were recorded by the National Seismological Network (RSN: UCR-ICE) for the six-month period after the Nicoya event was two times higher than that number of upper plate-earthquakes during the six months before it happened. We analyze the three largest upper-plate earthquake swarms that took place during the first six months after the Nicoya event. We relocate the epicenters using a double difference algorithm with a 1D velocity model (HypoDD) and using a probabilistic method with a 3D velocity model (NonLinLoc). Additionally we compute first motion focal mechanisms for the largest events. The three swarms analyzed occurred at distances of 170 to 350 km from the Nicoya source region in three different tectonic settings: the Cartago area in the central part of Costa Rica near the active volcanic arc (approximately 170 km from the source region), the Calero Island near the Costa Rica-Nicaragua border in the backarc Caribbean region (approximately 220 km), and the San Vito area in the Costa Rica-Panama border region, at the southern flank of the Talamanca Cordillera, an inactive portion of the magmatic arc (approximately 300 km). The Cartago swarm with 95 1.8-to-4.1 Mw earthquakes occurred from September 5 to October 31, 2012. The location and left-lateral solution of the largest event suggest that the Aguacaliente fault, which caused the deadliest earthquake in Costa Rican history on May 4, 1910 (Ms 6.4), is the source of some of this triggered seismicity. Moreover, seismicity patterns suggest activity on the Navarro, Queveri, Rio Macho, and Ochomogo Faults. The Calero swarm with 70 2.5-to-4.2 Mw earthquakes took place from September 22 to October 2, 2012. The earthquake pattern suggests a possible extension of the Hess Escarpment inland. The San Vito earthquake swarm with 21 2.3-to-4.5 Mw earthquakes occurred between October 14, 2012 and January 28, 2013. These earthquakes occurred mainly in the region between the North-South oriented San Vito and Sereno-Alturas Faults, which are located along the inland projection of the Panama Fracture Zone. Documenting remotely triggered earthquakes may provide us with insights into the physics of the earthquake cycle, and may greatly improve seismic hazards assessment by illuminating active structures within the interior of Costa Rica and by pointing to where the next upper-plate earthquakes might be located.

  19. Earthquake faulting in subduction zones: insights from fault rocks in accretionary prisms

    NASA Astrophysics Data System (ADS)

    Ujiie, Kohtaro; Kimura, Gaku

    2014-12-01

    Subduction earthquakes on plate-boundary megathrusts accommodate most of the global seismic moment release, frequently resulting in devastating damage by ground shaking and tsunamis. As many earthquakes occur in deep-sea regions, the dynamics of earthquake faulting in subduction zones is poorly understood. However, the Integrated Ocean Drilling Program (IODP) Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) and fault rock studies in accretionary prisms exhumed from source depths of subduction earthquakes have greatly improved our understanding of earthquake faulting in subduction zones. Here, we review key advances that have been made over the last decade in the studies of fault rocks and in laboratory experiments using fault zone materials, with a particular focus on the Nankai Trough subduction zone and its on-land analog, the Shimanto accretionary complex in Japan. New insights into earthquake faulting in subduction zones are summarized in terms of the following: (1) the occurrence of seismic slip along velocity-strengthening materials both at shallow and deep depths; (2) dynamic weakening of faults by melt lubrication and fluidization, and possible factors controlling coseismic deformation mechanisms; (3) fluid-rock interactions and mineralogical and geochemical changes during earthquakes; and (4) geological and experimental aspects of slow earthquakes.

  20. Earthquake precursory events around epicenters and local active faults

    NASA Astrophysics Data System (ADS)

    Valizadeh Alvan, H.; Mansor, S. B.; Haydari Azad, F.

    2013-05-01

    The chain of underground events which are triggered by seismic activities and physical/chemical interactions prior to a shake in the earth's crust may produce surface and above surface phenomena. During the past decades many researchers have been carried away to seek the possibility of short term earthquake prediction using remote sensing data. Currently, there are several theories about the preparation stages of earthquakes most of which stress on raises in heat and seismic waves as the main signs of an impending earthquakes. Their differences only lie in the secondary phenomena which are triggered by these events. In any case, with the recent advances in remote sensing sensors and techniques now we are able to provide wider, more accurate monitoring of land, ocean and atmosphere. Among all theoretical factors, changes in Surface Latent Heat Flux (SLHF), Sea & Land Surface Temperature (SST & LST) and surface chlorophyll-a are easier to record from earth observing satellites. SLHF is the amount of energy exchange in the form of water vapor between the earth's surface and atmosphere. Abnormal variations in this factor have been frequently reported as an earthquake precursor during the past years. The accumulated stress in the earth's crust during the preparation phase of earthquakes is said to be the main cause of temperature anomalies weeks to days before the main event and subsequent shakes. Chemical and physical interactions in the presence of underground water lead to higher water evaporation prior to inland earthquakes. In case of oceanic earthquakes, higher temperature at the ocean beds may lead to higher amount of Chl-a on the sea surface. On the other hand, it has been also said that the leak of Radon gas which occurs as rocks break during earthquake preparation causes the formation of airborne ions and higher Air Temperature (AT). We have chosen to perform a statistical, long-term, and short-term approach by considering the reoccurrence intervals of past shakes, mapping foreshocks and aftershocks, and following changes in the above-mentioned precursors prior to past earthquake instances all over the globe. Our analyses also encompass the geographical location and extents of local and regional faults which are considered as important factors during earthquakes. The co-analysis of direct and indirect observation for precursory events is considered as a promising method for possible future successful earthquake predictions. With proper and thorough knowledge about the geological setting, atmospheric factors and geodynamics of the earthquake-prone regions we will be able to identify anomalies due to seismic activity in the earth's crust.

  1. Space-time model for repeating earthquakes and analysis of recurrence intervals on the San Andreas Fault near Parkfield, California

    NASA Astrophysics Data System (ADS)

    Nomura, Shunichi; Ogata, Yosihiko; Nadeau, Robert M.

    2014-09-01

    We propose a stochastic model for characteristically repeating earthquake sequences to estimate the spatiotemporal change in static stress loading rate. These earthquakes recur by a cyclic mechanism where stress at a hypocenter is accumulated by tectonic forces until an earthquake occurs that releases the accumulated stress to a basal level. Renewal processes are frequently used to describe this repeating earthquake mechanism. Variations in the rate of tectonic loading due to large earthquakes and aseismic slip transients, however, introduce nonstationary effects into the repeating mechanism that result in nonstationary trends in interevent times, particularly for smaller-magnitude repeating events which have shorter interevent times. These trends are also similar among repeating earthquake sites having similar hypocenters. Therefore, we incorporate space-time structure represented by cubic B-spline functions into the renewal model and estimate their coefficient parameters by maximizing the integrated likelihood in a Bayesian framework. We apply our model to 31 repeating earthquake sequences including 824 events on the Parkfield segment of the San Andreas Fault and estimate the spatiotemporal transition of the loading rate on this segment. The result gives us details of the change in tectonic loading caused by an aseismic slip transient in 1993, the 2004 Parkfield M6 earthquake, and other nearby or remote seismic activities. The degree of periodicity of repeating event recurrence intervals also shows spatial trends that are preserved in time even after the 2004 Parkfield earthquake when time scales are normalized with respect to the estimated loading rate.

  2. Living with earthquakes - development and usage of earthquake-resistant construction methods in European and Asian Antiquity

    NASA Astrophysics Data System (ADS)

    Kázmér, Miklós; Major, Balázs; Hariyadi, Agus; Pramumijoyo, Subagyo; Ditto Haryana, Yohanes

    2010-05-01

    Earthquakes are among the most horrible events of nature due to unexpected occurrence, for which no spiritual means are available for protection. The only way of preserving life and property is applying earthquake-resistant construction methods. Ancient Greek architects of public buildings applied steel clamps embedded in lead casing to hold together columns and masonry walls during frequent earthquakes in the Aegean region. Elastic steel provided strength, while plastic lead casing absorbed minor shifts of blocks without fracturing rigid stone. Romans invented concrete and built all sizes of buildings as a single, unflexible unit. Masonry surrounding and decorating concrete core of the wall did not bear load. Concrete resisted minor shaking, yielding only to forces higher than fracture limits. Roman building traditions survived the Dark Ages and 12th century Crusader castles erected in earthquake-prone Syria survive until today in reasonably good condition. Concrete and steel clamping persisted side-by-side in the Roman Empire. Concrete was used for cheap construction as compared to building of masonry. Applying lead-encased steel increased costs, and was avoided whenever possible. Columns of the various forums in Italian Pompeii mostly lack steel fittings despite situated in well-known earthquake-prone area. Whether frequent recurrence of earthquakes in the Naples region was known to inhabitants of Pompeii might be a matter of debate. Seemingly the shock of the AD 62 earthquake was not enough to apply well-known protective engineering methods throughout the reconstruction of the city before the AD 79 volcanic catastrophe. An independent engineering tradition developed on the island of Java (Indonesia). The mortar-less construction technique of 8-9th century Hindu masonry shrines around Yogyakarta would allow scattering of blocks during earthquakes. To prevent dilapidation an intricate mortise-and-tenon system was carved into adjacent faces of blocks. Only the outermost layer was treated this way, the core of the shrines was made of simple rectangular blocks. The system resisted both in-plane and out-of-plane shaking quite well, as proven by survival of many shrines for more than a millennium, and by fracturing of blocks instead of displacement during the 2006 Yogyakarta earthquake. Systematic use or disuse of known earthquake-resistant techniques in any one society depends on the perception of earthquake risk and on available financial resources. Earthquake-resistant construction practice is significantly more expensive than regular construction. Perception is influenced mostly by short individual and longer social memory. If earthquake recurrence time is longer than the preservation of social memory, if damaging quakes fade into the past, societies commit the same construction mistakes again and again. Length of the memory is possibly about a generation's lifetime. Events occurring less frequently than 25-30 years can be readily forgotten, and the risk of recurrence considered as negligible, not worth the costs of safe construction practices. (Example of recurring flash floods in Hungary.) Frequent earthquakes maintain safe construction practices, like the Java masonry technique throughout at least two centuries, and like the Fachwerk tradition on Modern Aegean Samos throughout 500 years of political and technological development. (OTKA K67583)

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    Last October 21st marked the 140th anniversary of the M6.8 1868 Hayward Earthquake, the last damaging earthquake on the southern Hayward Fault. This anniversary was used to help publicize the seismic hazards associated with the fault because: (1) the past five such earthquakes on the Hayward Fault occurred about 140 years apart on average, and (2) the Hayward-Rodgers Creek Fault system is the most likely (with a 31 percent probability) fault in the Bay Area to produce a M6.7 or greater earthquake in the next 30 years. To promote earthquake awareness and preparedness, over 140 public and private agencies and companies and many individual joined the public-private nonprofit 1868 Hayward Earthquake Alliance (1868alliance.org). The Alliance sponsored many activities including a public commemoration at Mission San Jose in Fremont, which survived the 1868 earthquake. This event was followed by an earthquake drill at Bay Area schools involving more than 70,000 students. The anniversary prompted the Silver Sentinel, an earthquake response exercise based on the scenario of an earthquake on the Hayward Fault conducted by Bay Area County Offices of Emergency Services. 60 other public and private agencies also participated in this exercise. The California Seismic Safety Commission and KPIX (CBS affiliate) produced professional videos designed forschool classrooms promoting Drop, Cover, and Hold On. Starting in October 2007, the Alliance and the U.S. Geological Survey held a sequence of press conferences to announce the release of new research on the Hayward Fault as well as new loss estimates for a Hayward Fault earthquake. These included: (1) a ShakeMap for the 1868 Hayward earthquake, (2) a report by the U. S. Bureau of Labor Statistics forecasting the number of employees, employers, and wages predicted to be within areas most strongly shaken by a Hayward Fault earthquake, (3) new estimates of the losses associated with a Hayward Fault earthquake, (4) new ground motion simulations of a Hayward Fault earthquake, (5) a new USGS Fact Sheet about the earthquake and the Hayward Fault, (6) a virtual tour of the 1868 earthquake, and (7) a new online field trip guide to the Hayward Fault using locations accessible by car and public transit. Finally, the California Geological Survey and many other Alliance members sponsored the Third Conference on Earthquake Hazards in the East Bay at CSU East Bay in Hayward for the three days following the 140th anniversary. The 1868 Alliance hopes to commemorate the anniversary of the 1868 Hayward Earthquake every year to maintain and increase public awareness of this fault, the hazards it and other East Bay Faults pose, and the ongoing need for earthquake preparedness and mitigation.

  4. Frequently Asked Questions and Answers on Smallpox

    MedlinePlus

    ... Biorisk reduction Frequently asked questions and answers on smallpox What is smallpox? Does it occur naturally? How ... protected? What is WHO doing now? What is smallpox? Smallpox is an ancient disease caused by the ...

  5. Education for Earthquake Disaster Prevention in the Tokyo Metropolitan Area

    NASA Astrophysics Data System (ADS)

    Oki, S.; Tsuji, H.; Koketsu, K.; Yazaki, Y.

    2008-12-01

    Japan frequently suffers from all types of disasters such as earthquakes, typhoons, floods, volcanic eruptions, and landslides. In the first half of this year, we already had three big earthquakes and heavy rainfall, which killed more than 30 people. This is not just for Japan but Asia is the most disaster-afflicted region in the world, accounting for about 90% of all those affected by disasters, and more than 50% of the total fatalities and economic losses. One of the most essential ways to reduce the damage of natural disasters is to educate the general public to let them understand what is going on during those desasters. This leads individual to make the sound decision on what to do to prevent or reduce the damage. The Ministry of Education, Culture, Sports, Science and Technology (MEXT), therefore, offered for public subscription to choose several model areas to adopt scientific education to the local elementary schools, and ERI, the Earthquake Research Institute, is qualified to develop education for earthquake disaster prevention in the Tokyo metropolitan area. The tectonic setting of this area is very complicated; there are the Pacific and Philippine Sea plates subducting beneath the North America and the Eurasia plates. The subduction of the Philippine Sea plate causes mega-thrust earthquakes such as the 1703 Genroku earthquake (M 8.0) and the 1923 Kanto earthquake (M 7.9) which had 105,000 fatalities. A magnitude 7 or greater earthquake beneath this area is recently evaluated to occur with a probability of 70 % in 30 years. This is of immediate concern for the devastating loss of life and property because the Tokyo urban region now has a population of 42 million and is the center of approximately 40 % of the nation's activities, which may cause great global economic repercussion. To better understand earthquakes in this region, "Special Project for Earthquake Disaster Mitigation in Tokyo Metropolitan Area" has been conducted mainly by ERI. It is a 4-year project to develop a high-density network with 400 sites at local elementary schools. We start our education project by using the real seismograms observed at their own schoolyards, putting emphasis on the reality and causality of earthquake disasters. In this presentation, we report some of the educational demonstrations and science experiments for the school kids and their parents.

  6. Intraslab earthquakes: dehydration of the Cascadia slab.

    PubMed

    Preston, Leiph A; Creager, Kenneth C; Crosson, Robert S; Brocher, Thomas M; Trehu, Anne M

    2003-11-14

    We simultaneously invert travel times of refracted and wide-angle reflected waves for three-dimensional compressional-wave velocity structure, earthquake locations, and reflector geometry in northwest Washington state. The reflector, interpreted to be the crust-mantle boundary (Moho) of the subducting Juan de Fuca plate, separates intraslab earthquakes into two groups, permitting a new understanding of the origins of intraslab earthquakes in Cascadia. Earthquakes up-dip of the Moho's 45-kilometer depth contour occur below the reflector, in the subducted oceanic mantle, consistent with serpentinite dehydration; earthquakes located down-dip occur primarily within the subducted crust, consistent with the basalt-to-eclogite transformation. PMID:14615535

  7. Intrastab Earthquakes: Dehydration of the Cascadia Slab

    USGS Publications Warehouse

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

    2003-01-01

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

  8. Upper-Plate Seismicity Remotely Triggered by the 2012 Mw-7.6 Nicoya Earthquake, Costa Rica

    NASA Astrophysics Data System (ADS)

    Linkimer, L.; Arroyo, I. G.; Montero Pohly, W. K.; Lücke, O. H.

    2014-12-01

    Remotely triggered seismicity that takes place at distances greater than 1-2 fault lengths appears to be a frequent phenomenon after large earthquakes, including examples in Costa Rica after the large (Mw > 7.0) inter-plate earthquakes in 1941, 1950, 1983, 1990, and 1991. On September 5, 2012, an inter-plate 7.6-Mw earthquake struck the Nicoya Peninsula, triggering upper-plate seismicity in the interior of Costa Rica. In this study, we analyze the largest earthquakes and earthquake swarms that took place during the first nine months after the Nicoya earthquake. These swarms occurred at distances of 150 to 450 km from the Nicoya source region in different tectonic settings: the Calero Island near the Costa Rica-Nicaragua border in the backarc Caribbean region, the Sixaola region near the Costa Rica-Panama border in the backarc Caribbean region, the Cartago area in the central part of Costa Rica near the active volcanic arc, and the San Vito area in the Costa Rica-Panama border region, at the southern flank of the Talamanca Cordillera in an inactive portion of the magmatic arc. The Calero swarm with 70 2.0-to-4.2 Mw earthquakes took place from September 22 to October 9, 2012. The earthquake pattern suggests a smaller-scale fault as a possible source, which is located along the inland projection of the Hess Escarpment. The Cartago swarm with 284 1.8-to-4.1 Mw earthquakes occurred from September 5 to October 31, 2012. The focal mechanism solutions suggest that strike-slip faulting predominates in this region, consistent with neotectonic observations. The San Vito earthquake swarm with 30 2.3-to-4.5 Mw earthquakes occurred between October 14, 2012 and January 28, 2013. These earthquakes occurred in the vicinity of north-south striking faults, which are located along the inland projection of the Panama Fracture Zone. The largest earthquake (5.6 Mw) occurred on the Sixaola region on 27 of May, 2013. The focal mechanism solution suggests a thrust fault that correlates with the North Panama Deformed Belt. Documenting remotely triggered earthquakes may greatly improve seismic hazards assessment by illuminating active structures within the interior of Costa Rica.

  9. Earthquake prediction

    NASA Technical Reports Server (NTRS)

    Turcotte, Donald L.

    1991-01-01

    The state of the art in earthquake prediction is discussed. Short-term prediction based on seismic precursors, changes in the ratio of compressional velocity to shear velocity, tilt and strain precursors, electromagnetic precursors, hydrologic phenomena, chemical monitors, and animal behavior is examined. Seismic hazard assessment is addressed, and the applications of dynamical systems to earthquake prediction are discussed.

  10. Earthquake Hazards.

    ERIC Educational Resources Information Center

    Donovan, Neville

    1979-01-01

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

  11. Triggering of repeated earthquakes

    NASA Astrophysics Data System (ADS)

    Sobolev, G. A.; Zakrzhevskaya, N. A.; Sobolev, D. G.

    2016-03-01

    Based on the analysis of the world's earthquakes with magnitudes M ≥ 6.5 for 1960-2013, it is shown that they cause global-scale coherent seismic oscillations which most distinctly manifest themselves in the period interval of 4-6 min during 1-3 days after the event. After these earthquakes, a repeated shock has an increased probability to occur in different seismically active regions located as far away as a few thousand km from the previous event, i.e., a remote interaction of seismic events takes place. The number of the repeated shocks N( t) decreases with time, which characterizes the memory of the lithosphere about the impact that has occurred. The time decay N( t) can be approximated by the linear, exponential, and powerlaw dependences. No distinct correlation between the spatial locations of the initial and repeated earthquakes is revealed. The probable triggering mechanisms of the remote interaction between the earthquakes are discussed. Surface seismic waves traveling several times around the Earth's, coherent oscillations, and global source are the most preferable candidates. This may lead to the accumulation and coalescence of ruptures in the highly stressed or weakened domains of a seismically active region, which increases the probability of a repeated earthquake.

  12. Earthquake precursory events around epicenters and local active faults; the cases of two inland earthquakes in Iran

    NASA Astrophysics Data System (ADS)

    Valizadeh Alvan, H.; Mansor, S.; Haydari Azad, F.

    2012-12-01

    The possibility of earthquake prediction in the frame of several days to few minutes before its occurrence has stirred interest among researchers, recently. Scientists believe that the new theories and explanations of the mechanism of this natural phenomenon are trustable and can be the basis of future prediction efforts. During the last thirty years experimental researches resulted in some pre-earthquake events which are now recognized as confirmed warning signs (precursors) of past known earthquakes. With the advances in in-situ measurement devices and data analysis capabilities and the emergence of satellite-based data collectors, monitoring the earth's surface is now a regular work. Data providers are supplying researchers from all over the world with high quality and validated imagery and non-imagery data. Surface Latent Heat Flux (SLHF) or the amount of energy exchange in the form of water vapor between the earth's surface and atmosphere has been frequently reported as an earthquake precursor during the past years. The accumulated stress in the earth's crust during the preparation phase of earthquakes is said to be the main cause of temperature anomalies weeks to days before the main event and subsequent shakes. Chemical and physical interactions in the presence of underground water lead to higher water evaporation prior to inland earthquakes. On the other hand, the leak of Radon gas occurred as rocks break during earthquake preparation causes the formation of airborne ions and higher Air Temperature (AT) prior to main event. Although co-analysis of direct and indirect observation for precursory events is considered as a promising method for future successful earthquake prediction, without proper and thorough knowledge about the geological setting, atmospheric factors and geodynamics of the earthquake-prone regions we will not be able to identify anomalies due to seismic activity in the earth's crust. Active faulting is a key factor in identification of the source and propagation of seismic waves. In many cases, active faults are capable of buildup and sudden release of tectonic stress. Hence, monitoring the active fault systems near epicentral regions of past earthquakes would be a necessity. In this paper, we try to detect possible anomalies in SLHF and AT during two moderate earthquakes of 6 - 6.5 M in Iran and explain the relationships between the seismic activities prior to these earthquake and active faulting in the area. Our analysis shows abnormal SLHF 5~10 days before these earthquakes. Meaningful anomalous concentrations usually occurred in the epicentral area. On the other hand, spatial distributions of these variations were in accordance with the local active faults. It is concluded that the anomalous increase in SLHF shows great potential in providing early warning of a disastrous earthquake, provided that there is a better understanding of the background noise due to the seasonal effects and climatic factors involved. Changes in near surface air temperature along nearby active faults, one or two weeks before the earthquakes, although not as significant as SLHF changes, can be considered as another earthquake indicator.

  13. Seismology: Remote-controlled earthquakes

    NASA Astrophysics Data System (ADS)

    Hayes, Gavin

    2016-04-01

    Large earthquakes cause other quakes near and far. Analyses of quakes in Pakistan and Chile suggest that such triggering can occur almost instantaneously, making triggered events hard to detect, and potentially enhancing the associated hazards.

  14. Earthquakes in Stable Continental Crust.

    ERIC Educational Resources Information Center

    Johnston, Arch C.; Kanter, Lisa R.

    1990-01-01

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

  15. Analog earthquakes

    SciTech Connect

    Hofmann, R.B.

    1995-09-01

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

  16. Earthquake damage to schools

    USGS Publications Warehouse

    McCullough, Heather

    1994-01-01

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

  17. Modern Earthquake Hazard Assessments in Afghanistan: A USGS Training Course

    NASA Astrophysics Data System (ADS)

    Garthwaite, M.; Mooney, W. D.; Medlin, J.; Holzer, T.; McGarr, A.; Bohannon, R.

    2007-12-01

    Afghanistan is located in a tectonically active region at the western extent of the Indo-Asian collision zone, where ongoing deformation has generated rugged mountainous terrain, and where large earthquakes occur frequently. These earthquakes can cause damage, not only from strong ground shaking and surface rupture, but also from liquefaction and extensive landsliding. The M=6.1 earthquake of March 25, 2002 highlighted the vulnerability of Afghan communities to such hazards, and resulted in at least 1000 fatalities. This training course in modern earthquake hazard assessments is an integral part of the international effort to provide technical assistance to Afghanistan using an "end-to-end" approach. This approach involves providing assistance in all stages of hazard assessment, from identifying earthquakes, to disseminating information on mitigation strategies to the public. The purpose of this training course, held December 2-6, 2006 at the Afghan Geological Survey in Kabul, was to provide a solid background in the relevant seismological and geological methods for preparing for future earthquakes. With this information, participants may now be expected to educate other members of the Afghan community. In addition, they are better prepared to conduct earthquake hazard assessments and to build the capabilities of the Afghan Geological Survey. The training course was taught using a series of Power Point lectures, with all lectures being presented in English and translated into Dari, one of the two main languages of Afghanistan. The majority of lecture slides were also annotated in both English and Dari. Lectures were provided to the students in both hardcopy and digital formats. As part of the on-going USGS participation in the program, additional training sessions are planned in the subjects of field geology, modern concepts in Earth science, mineral resource assessments and applied geophysics.

  18. Road Damage from 2008 Great Sichuan Earthquake in China

    The May 12, 2008, Great Sichuan Earthquake, also called the Wenchuan Earthquake, occurred at 14:28 local time, in Sichuan Province, China. The earthquake magnitudes were Mw = 7.9 (USGS), Ms = 8.0 (Chinese Earthquake Administration). The epicenter was 80 km west-northwest of Chengdu, the capital city...

  19. Boulder from 2008 Great Sichuan Earthquake in China

    The May 12, 2008, Great Sichuan Earthquake, also called the Wenchuan Earthquake, occurred at 14:28 local time, in Sichuan Province, China. The earthquake magnitudes were Mw = 7.9 (USGS), Ms = 8.0 (Chinese Earthquake Administration). The epicenter was 80 km west-northwest of Chengdu, the capital city...

  20. Damage from 2008 Great Sichuan Earthquake in China

    The May 12, 2008, Great Sichuan Earthquake, also called the Wenchuan Earthquake, occurred at 14:28 local time, in Sichuan Province, China. The earthquake magnitudes were Mw = 7.9 (USGS), Ms = 8.0 (Chinese Earthquake Administration). The epicenter was 80 km west-northwest of Chengdu, the capital city...

  1. Earthquake Drill using the Earthquake Early Warning System at an Elementary School

    NASA Astrophysics Data System (ADS)

    Oki, Satoko; Yazaki, Yoshiaki; Koketsu, Kazuki

    2010-05-01

    Japan frequently suffers from many kinds of disasters such as earthquakes, typhoons, floods, volcanic eruptions, and landslides. On average, we lose about 120 people a year due to natural hazards in this decade. Above all, earthquakes are noteworthy, since it may kill thousands of people in a moment like in Kobe in 1995. People know that we may have "a big one" some day as long as we live on this land and that what to do; retrofit houses, appliance heavy furniture to walls, add latches to kitchen cabinets, and prepare emergency packs. Yet most of them do not take the action, and result in the loss of many lives. It is only the victims that learn something from the earthquake, and it has never become the lore of the nations. One of the most essential ways to reduce the damage is to educate the general public to be able to make the sound decision on what to do at the moment when an earthquake hits. This will require the knowledge of the backgrounds of the on-going phenomenon. The Ministry of Education, Culture, Sports, Science and Technology (MEXT), therefore, offered for public subscription to choose several model areas to adopt scientific education to the local elementary schools. This presentation is the report of a year and half courses that we had at the model elementary school in Tokyo Metropolitan Area. The tectonic setting of this area is very complicated; there are the Pacific and Philippine Sea plates subducting beneath the North America and the Eurasia plates. The subduction of the Philippine Sea plate causes mega-thrust earthquakes such as the 1923 Kanto earthquake (M 7.9) making 105,000 fatalities. A magnitude 7 or greater earthquake beneath this area is recently evaluated to occur with a probability of 70 % in 30 years. This is of immediate concern for the devastating loss of life and property because the Tokyo urban region now has a population of 42 million and is the center of approximately 40 % of the nation's activities, which may cause great global economic repercussion. We provide the school kids with the "World Seismicity Map" to let them realize that earthquake disasters take place unequally. Then we let the kids jump in front of the seismometer with projecting the real-time data to the wall. Grouped kids contest the largest amplitude by carefully considering how to jump high but nail the landing with their teammates. Their jumps are printed out via portable printer and compared with the real earthquake which occurred even 600km away but still huge when printed out in the same scale. Actually, a magnitude 7 earthquake recorded 600km away needs an A0 paper when scaled with a jump of 10 kids printed in an A4 paper. They've got to understand what to do not to be killed with the great big energy. We also offer earthquake drills using the Earthquake Early Warning System (EEW System). An EEW System is officially introduced in 2007 by JMA (Japan Meteorological Agency) to issue prompt alerts to provide several to several ten seconds before S-wave arrives. When hearing the alarm, school kids think fast to find a place to protect themselves. It is not always when they are in their classrooms but in the chemical lab, music room which does not have any desks to protect them, or in the PE class. Then in the science class, we demonstrate how the EEW System works. A 8m long wave propagation device made with spindles connected with springs is used to visualize the P- and S-waves. In the presentation, we would like to show the paper materials and sufficient movies.

  2. How Frequently Are Elementary Students Writing?

    ERIC Educational Resources Information Center

    Sunflower, Cherlyn; Crawford, Leslie W.

    A study examined elementary school writing instruction to determine (1) how frequently students are writing, (2) when in the curriculum writing occurs, and (3) in what forms the writing occurs. Data were collected in 75 elementary classrooms in 25 midwestern schools during a 15-day period. The data deviated little from what D. Graves reported in…

  3. Complex earthquake rupture and local tsunamis

    USGS Publications Warehouse

    Geist, E.L.

    2002-01-01

    In contrast to far-field tsunami amplitudes that are fairly well predicted by the seismic moment of subduction zone earthquakes, there exists significant variation in the scaling of local tsunami amplitude with respect to seismic moment. From a global catalog of tsunami runup observations this variability is greatest for the most frequently occuring tsunamigenic subduction zone earthquakes in the magnitude range of 7 < Mw < 8.5. Variability in local tsunami runup scaling can be ascribed to tsunami source parameters that are independent of seismic moment: variations in the water depth in the source region, the combination of higher slip and lower shear modulus at shallow depth, and rupture complexity in the form of heterogeneous slip distribution patterns. The focus of this study is on the effect that rupture complexity has on the local tsunami wave field. A wide range of slip distribution patterns are generated using a stochastic, self-affine source model that is consistent with the falloff of far-field seismic displacement spectra at high frequencies. The synthetic slip distributions generated by the stochastic source model are discretized and the vertical displacement fields from point source elastic dislocation expressions are superimposed to compute the coseismic vertical displacement field. For shallow subduction zone earthquakes it is demonstrated that self-affine irregularities of the slip distribution result in significant variations in local tsunami amplitude. The effects of rupture complexity are less pronounced for earthquakes at greater depth or along faults with steep dip angles. For a test region along the Pacific coast of central Mexico, peak nearshore tsunami amplitude is calculated for a large number (N = 100) of synthetic slip distribution patterns, all with identical seismic moment (Mw = 8.1). Analysis of the results indicates that for earthquakes of a fixed location, geometry, and seismic moment, peak nearshore tsunami amplitude can vary by a factor of 3 or more. These results indicate that there is substantially more variation in the local tsunami wave field derived from the inherent complexity subduction zone earthquakes than predicted by a simple elastic dislocation model. Probabilistic methods that take into account variability in earthquake rupture processes are likely to yield more accurate assessments of tsunami hazards.

  4. Tectonic controls on earthquake size distribution and seismicity rate: slab buoyancy and slab bending

    NASA Astrophysics Data System (ADS)

    Nishikawa, T.; Ide, S.

    2014-12-01

    There are clear variations in maximum earthquake magnitude among Earth's subduction zones. These variations have been studied extensively and attributed to differences in tectonic properties in subduction zones, such as relative plate velocity and subducting plate age [Ruff and Kanamori, 1980]. In addition to maximum earthquake magnitude, the seismicity of medium to large earthquakes also differs among subduction zones, such as the b-value (i.e., the slope of the earthquake size distribution) and the frequency of seismic events. However, the casual relationship between the seismicity of medium to large earthquakes and subduction zone tectonics has been unclear. Here we divide Earth's subduction zones into over 100 study regions following Ide [2013] and estimate b-values and the background seismicity rate—the frequency of seismic events excluding aftershocks—for subduction zones worldwide using the maximum likelihood method [Utsu, 1965; Aki, 1965] and the epidemic type aftershock sequence (ETAS) model [Ogata, 1988]. We demonstrate that the b-value varies as a function of subducting plate age and trench depth, and that the background seismicity rate is related to the degree of slab bending at the trench. Large earthquakes tend to occur relatively frequently (lower b-values) in shallower subduction zones with younger slabs, and more earthquakes occur in subduction zones with deeper trench and steeper dip angle. These results suggest that slab buoyancy, which depends on subducting plate age, controls the earthquake size distribution, and that intra-slab faults due to slab bending, which increase with the steepness of the slab dip angle, have influence on the frequency of seismic events, because they produce heterogeneity in plate coupling and efficiently inject fluid to elevate pore fluid pressure on the plate interface. This study reveals tectonic factors that control earthquake size distribution and seismicity rate, and these relationships between seismicity and tectonic properties may be useful for seismic risk assessment.

  5. Anthropogenic Triggering of Large Earthquakes

    NASA Astrophysics Data System (ADS)

    Mulargia, Francesco; Bizzarri, Andrea

    2014-08-01

    The physical mechanism of the anthropogenic triggering of large earthquakes on active faults is studied on the basis of experimental phenomenology, i.e., that earthquakes occur on active tectonic faults, that crustal stress values are those measured in situ and, on active faults, comply to the values of the stress drop measured for real earthquakes, that the static friction coefficients are those inferred on faults, and that the effective triggering stresses are those inferred for real earthquakes. Deriving the conditions for earthquake nucleation as a time-dependent solution of the Tresca-Von Mises criterion applied in the framework of poroelasticity yields that active faults can be triggered by fluid overpressures < 0.1 MPa. Comparing this with the deviatoric stresses at the depth of crustal hypocenters, which are of the order of 1-10 MPa, we find that injecting in the subsoil fluids at the pressures typical of oil and gas production and storage may trigger destructive earthquakes on active faults at a few tens of kilometers. Fluid pressure propagates as slow stress waves along geometric paths operating in a drained condition and can advance the natural occurrence of earthquakes by a substantial amount of time. Furthermore, it is illusory to control earthquake triggering by close monitoring of minor ``foreshocks'', since the induction may occur with a delay up to several years.

  6. Anthropogenic Triggering of Large Earthquakes

    PubMed Central

    Mulargia, Francesco; Bizzarri, Andrea

    2014-01-01

    The physical mechanism of the anthropogenic triggering of large earthquakes on active faults is studied on the basis of experimental phenomenology, i.e., that earthquakes occur on active tectonic faults, that crustal stress values are those measured in situ and, on active faults, comply to the values of the stress drop measured for real earthquakes, that the static friction coefficients are those inferred on faults, and that the effective triggering stresses are those inferred for real earthquakes. Deriving the conditions for earthquake nucleation as a time-dependent solution of the Tresca-Von Mises criterion applied in the framework of poroelasticity yields that active faults can be triggered by fluid overpressures < 0.1 MPa. Comparing this with the deviatoric stresses at the depth of crustal hypocenters, which are of the order of 1–10 MPa, we find that injecting in the subsoil fluids at the pressures typical of oil and gas production and storage may trigger destructive earthquakes on active faults at a few tens of kilometers. Fluid pressure propagates as slow stress waves along geometric paths operating in a drained condition and can advance the natural occurrence of earthquakes by a substantial amount of time. Furthermore, it is illusory to control earthquake triggering by close monitoring of minor “foreshocks”, since the induction may occur with a delay up to several years. PMID:25156190

  7. Charles Darwin's earthquake reports

    NASA Astrophysics Data System (ADS)

    Galiev, Shamil

    2010-05-01

    As it is the 200th anniversary of Darwin's birth, 2009 has also been marked as 170 years since the publication of his book Journal of Researches. During the voyage Darwin landed at Valdivia and Concepcion, Chile, just before, during, and after a great earthquake, which demolished hundreds of buildings, killing and injuring many people. Land was waved, lifted, and cracked, volcanoes awoke and giant ocean waves attacked the coast. Darwin was the first geologist to observe and describe the effects of the great earthquake during and immediately after. These effects sometimes repeated during severe earthquakes; but great earthquakes, like Chile 1835, and giant earthquakes, like Chile 1960, are rare and remain completely unpredictable. This is one of the few areas of science, where experts remain largely in the dark. Darwin suggested that the effects were a result of ‘ …the rending of strata, at a point not very deep below the surface of the earth…' and ‘…when the crust yields to the tension, caused by its gradual elevation, there is a jar at the moment of rupture, and a greater movement...'. Darwin formulated big ideas about the earth evolution and its dynamics. These ideas set the tone for the tectonic plate theory to come. However, the plate tectonics does not completely explain why earthquakes occur within plates. Darwin emphasised that there are different kinds of earthquakes ‘...I confine the foregoing observations to the earthquakes on the coast of South America, or to similar ones, which seem generally to have been accompanied by elevation of the land. But, as we know that subsidence has gone on in other quarters of the world, fissures must there have been formed, and therefore earthquakes...' (we cite the Darwin's sentences following researchspace. auckland. ac. nz/handle/2292/4474). These thoughts agree with results of the last publications (see Nature 461, 870-872; 636-639 and 462, 42-43; 87-89). About 200 years ago Darwin gave oneself airs by the problems which began to discuss only during the last time. Earthquakes often precede volcanic eruptions. According to Darwin, the earthquake-induced shock may be a common mechanism of the simultaneous eruptions of the volcanoes separated by long distances. In particular, Darwin wrote that ‘… the elevation of many hundred square miles of territory near Concepcion is part of the same phenomenon, with that splashing up, if I may so call it, of volcanic matter through the orifices in the Cordillera at the moment of the shock;…'. According to Darwin the crust is a system where fractured zones, and zones of seismic and volcanic activities interact. Darwin formulated the task of considering together the processes studied now as seismology and volcanology. However the difficulties are such that the study of interactions between earthquakes and volcanoes began only recently and his works on this had relatively little impact on the development of geosciences. In this report, we discuss how the latest data on seismic and volcanic events support the Darwin's observations and ideas about the 1835 Chilean earthquake. The material from researchspace. auckland. ac. nz/handle/2292/4474 is used. We show how modern mechanical tests from impact engineering and simple experiments with weakly-cohesive materials also support his observations and ideas. On the other hand, we developed the mathematical theory of the earthquake-induced catastrophic wave phenomena. This theory allow to explain the most important aspects the Darwin's earthquake reports. This is achieved through the simplification of fundamental governing equations of considering problems to strongly-nonlinear wave equations. Solutions of these equations are constructed with the help of analytic and numerical techniques. The solutions can model different strongly-nonlinear wave phenomena which generate in a variety of physical context. A comparison with relevant experimental observations is also presented.

  8. Nisqually, Washington Intraplate Earthquake

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Hofmeister, R.

    2001-05-01

    On February 28, 2001, the M6.8 Nisqually earthquake shook the Pacific Northwest. This intraplate event occurred within the subducting Juan de Fuca plate along the Cascadia margin. Although the damage was less than observed at most large urban earthquakes, serious damage was found in Olympia, Seattle, and Tacoma. To better serve Oregon public safety needs, DOGAMI and others surveyed the Puget Sound damage to expand our technical understanding of seismic ground response, building and lifeline behavior, and secondary hazards (landslides and liquefaction). Damage was observed in structures and areas that, for the most part, would be predicted to be vulnerable. These included: old buildings (URMs), old lifelines (4th Ave bridge in Olympia), areas with poor soil conditions (Harbor Island, Seattle; Sunset Lake, Tumwater), and steep slopes (Salmon Beach; Burien). Damage types included: structural, nonstructural, contents, lifelines, landslides, liquefaction, lateral spreading, sand boils, and settlement. In several notable places, seismic-induced ground failures significantly increased the damage. Estimated costs developed from HAZUS evaluations ranged from \\2 billion to \\3.9 billion. Historic intraplate earthquakes in the Puget Sound region, including the 1949 M7.1, 1965 M6.5, and 1999 M5.9, were not accompanied by significant aftershock events or associated with earthquake sequences. However, a recent El Salvador earthquake sequence suggests there may be particular cases of increased seismicity following large intraplate events, with implications for post-earthquake response and mitigation. The January 13, 2001 M7.6 El Salvador intraplate earthquake was followed by a M6.6 crustal event February 13, 2001 and a M5.4 intraplate event February 28, 2001.

  9. The CATDAT damaging earthquakes database

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

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

  10. Earthquake Analysis.

    ERIC Educational Resources Information Center

    Espinoza, Fernando

    2000-01-01

    Indicates the importance of the development of students' measurement and estimation skills. Analyzes earthquake data recorded at seismograph stations and explains how to read and modify the graphs. Presents an activity for student evaluation. (YDS)

  11. Cutaneous Leishmaniasis in Bam: A Comparative Evaluation of Pre- and Post-Earthquake Years (1999–2008)

    PubMed Central

    Sharifi, I; Nakhaei, N; Aflatoonian, MR; Parizi, M Hakimi; Fekri, AR; Safizadeh, H; Shirzadi, MR; Gooya, MM; Khamesipour, A; Nadim, A

    2011-01-01

    Background: The recent devastating earthquake of December 26 in Bam, 2003 created various risk factors; caused a sharp increase in incidence of anthroponotic cutaneous leishmaniasis (ACL) cases and reached to an epidemic proportion. The objective of this study was to evaluate the status of ACL cases five years before the earthquake compared to the cases occurred five years after the earthquake (1999–2008). Methods: Status of disease was assessed retrospectively for the five years before the earthquake and prospectively for the five years after the earthquake. Identification was confirmed by smear and polymerase chain reaction (PCR). Results: The mean annual incidence of ACL for the period from 1999 to 2003 was 1.9 per 1000 comparing to post earthquake period, which was 7.6 per 1000. Most of the infection was in individuals of <20 years, more frequently in females before the earthquake, whilst in contrast, there was a progressive rise in the number of cases, significantly in male individuals of >20 years (P< 0.0001) in post earthquake era. The anatomical distribution of lesions considerably changed during the two periods. Most of the cases were limited to three zones within the city prior to the earthquake, whereas it was spread throughout different zones after the earthquake. PCR indicated that the CL was due to Leishmania tropica in the city. Conclusion: The results strongly suggest that in natural disasters such as earthquakes various precipitating factors in favor of disease will be created, which in turn provide a suitable condition for propagation of the vector and the transmission of the parasite. PMID:23113072

  12. Earthquake Simulator Finds Tremor Triggers

    SciTech Connect

    Johnson, Paul

    2015-03-27

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

  13. Testing an earthquake prediction algorithm

    USGS Publications Warehouse

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

    1997-01-01

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

  14. Earthquake watch

    USGS Publications Warehouse

    Hill, M.

    1976-01-01

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

  15. Groundwater Ion Content Precursors of Strong Earthquakes in Kamchatka (Russia)

    NASA Astrophysics Data System (ADS)

    Biagi, P. F.; Ermini, A.; Kingsley, S. P.; Khatkevich, Y. M.; Gordeev, E. I.

    The Kamchatka peninsula, located in the far east of Russia, is a geologically active margin where the Pacific plate subducts beneath the North American and Eurasia plates. This area is characterised by frequent and strong seismic activity (magnitudes reaching 8.6) and epicentres are generally distributed offshore along the eastern coast of the peninsula. For many years, hydrogeochemicals have been sampled with a mean interval of three days to measure the most common ions in the groundwater of five deep wells in the southern area of the Kamchatka peninsula. In the last decade, five earthquakes with M > 6.5 have occurred at distances less than 250 km from these wells. These earthquakes were powerful enough for them to be considered as potential originators of precursors. In order to reveal possible precursors of these earthquakes, we analysed the groundwater ion contents. The quasi-periodic annual variation was filtered out, together with other slow trends, and then we smoothed out the high frequency fluctuations that arise from errors in a single measurement. When examining the data, we labelled each signal with an amplitude greater than three times the standard deviation as an irregularity and we made a first attempt at defining an anomaly as an irregularity occurring simultaneously in more than one parameter at each well. In a second definition we used the existence of an irregularity occurring simultaneously in each ion at more than one well. Then, on the basis of past results worldwide and the time interval between the earthquakes observed, we chose 158 days as the maximum temporal window between a possible anomaly and the subsequent earthquake. With the first anomaly definition we identified 6 anomalies with 4 possible successes and 2 failures. For the five earthquakes considered capable of producing precursors we obtained precursors in three cases. With the second anomaly definition we identified 10 anomalies with 7 possible successes and 3 failures and we obtained precursors in four of the five earthquakes. A schematic model explaining aspects of the complex relationship linking earthquakes and ion content anomalies is also presented.

  16. Unforecasted earthquake and forgotten tsunamis: Lessons from 2011 Tohoku event

    NASA Astrophysics Data System (ADS)

    Satake, K.

    2011-12-01

    The 11 March Tohoku earthquake was the largest (M~9) earthquake in Japan's history. Historical data indicated that large (M<8) earthquakes have repeated in Miyagi-oki since 1793 with an average recurrence interval of 37 years. Because the most recent event occurred in 1978, the probability of an earthquake in the next 30 years was forecasted as 99 %, the highest number of such a long-term forecast around Japan. The March event, however, was not a characteristic type as repeated in the last few centuries, but the size and spatial extent far exceeded the forecast. Very few seismologists anticipated such a gigantic earthquake would occur around Japan. The March earthquake caused about 20,000 fatalities, mostly from its tsunami. Such devastating tsunami was not the first one in Japan. The Sanriku coast, a sawtooth-shaped submerging coast of northern Tohoku, has suffered from damaging tsunamis in the last century. The 1960 Chilean tsunami was about 3 to 5 m high, and caused about 120 fatalities. The 1933 Sanriku tsunami caused up to 20 m tsunami and about 3,000 fatalities. The 1896 Sanriku tsunami caused more than 30 m tsunami with 22,000 fatalities. The 2011 tsunami heights and fatalities were roughly comparable to those from the 1896 tsunami. To the south of Sanriku coast around Sendai, the coastlines are simpler and characterized by flat plains. While the above historic tsunamis were not high on Sendai plain, a historical document and recent geological studies of tsunami deposits have shown that AD 869 Jogan tsunami caused several km of tsunami inundation and a thousand fatalities, very similar to the 2011 tsunami. However, tsunami hazard maps were constructed for the characteristic earthquake with high probability. On March 11, the tsunami warning message was issued by Japan Meteorological Agency (JMA) within 3 minutes of the earthquake. The rupture process of the giant earthquake took a few minutes to complete, hence the estimated earthquake size for the tsunami warning was underestimated. The tsunami arrival time and coastal heights calculated for an earthquake of M 7.9 were announced with tsunami warning message. When a few meters of tsunami was detected on offshore tsunami gauges, JMA upgraded the tsunami warning level, but this information did not reach all the coastal residents particularly at heavily damaged area. The March earthquake and tsunami disaster left many lessons. (1) the long-term forecast should consider prehistoric paleoseismological data, even if historical data for centuries are available, (2) tsunami hazard maps may need to be prepared for infrequent gigantic earthquakes as well as more frequent smaller-sized earthquakes, (3) the past tsunami disaster must be remembered and transmitted to next generation, and (4) upgrading tsunami warning level in emergency situation is rather difficult.

  17. Frequently Asked Questions about Rotavirus

    MedlinePlus

    ... Humanitarian Award Maxwell Finland Award for Scientific Achievement John P. Utz Leadership Award Dr. Charles Mérieux Award ... rotavirus, including: Frequent, watery diarrhea (often foul-smelling, green or brown) Frequent vomiting Fever Abdominal pain The ...

  18. Predicted Surface Displacements for Scenario Earthquakes in the San Francisco Bay Region

    USGS Publications Warehouse

    Murray-Moraleda, Jessica R.

    2008-01-01

    In the immediate aftermath of a major earthquake, the U.S. Geological Survey (USGS) will be called upon to provide information on the characteristics of the event to emergency responders and the media. One such piece of information is the expected surface displacement due to the earthquake. In conducting probabilistic hazard analyses for the San Francisco Bay Region, the Working Group on California Earthquake Probabilities (WGCEP) identified a series of scenario earthquakes involving the major faults of the region, and these were used in their 2003 report (hereafter referred to as WG03) and the recently released 2008 Uniform California Earthquake Rupture Forecast (UCERF). Here I present a collection of maps depicting the expected surface displacement resulting from those scenario earthquakes. The USGS has conducted frequent Global Positioning System (GPS) surveys throughout northern California for nearly two decades, generating a solid baseline of interseismic measurements. Following an earthquake, temporary GPS deployments at these sites will be important to augment the spatial coverage provided by continuous GPS sites for recording postseismic deformation, as will the acquisition of Interferometric Synthetic Aperture Radar (InSAR) scenes. The information provided in this report allows one to anticipate, for a given event, where the largest displacements are likely to occur. This information is valuable both for assessing the need for further spatial densification of GPS coverage before an event and prioritizing sites to resurvey and InSAR data to acquire in the immediate aftermath of the earthquake. In addition, these maps are envisioned to be a resource for scientists in communicating with emergency responders and members of the press, particularly during the time immediately after a major earthquake before displacements recorded by continuous GPS stations are available.

  19. Effects of acoustic waves on stick-slip in granular media and implications for earthquakes

    USGS Publications Warehouse

    Johnson, P.A.; Savage, H.; Knuth, M.; Gomberg, J.; Marone, C.

    2008-01-01

    It remains unknown how the small strains induced by seismic waves can trigger earthquakes at large distances, in some cases thousands of kilometres from the triggering earthquake, with failure often occurring long after the waves have passed. Earthquake nucleation is usually observed to take place at depths of 10-20 km, and so static overburden should be large enough to inhibit triggering by seismic-wave stress perturbations. To understand the physics of dynamic triggering better, as well as the influence of dynamic stressing on earthquake recurrence, we have conducted laboratory studies of stick-slip in granular media with and without applied acoustic vibration. Glass beads were used to simulate granular fault zone material, sheared under constant normal stress, and subject to transient or continuous perturbation by acoustic waves. Here we show that small-magnitude failure events, corresponding to triggered aftershocks, occur when applied sound-wave amplitudes exceed several microstrain. These events are frequently delayed or occur as part of a cascade of small events. Vibrations also cause large slip events to be disrupted in time relative to those without wave perturbation. The effects are observed for many large-event cycles after vibrations cease, indicating a strain memory in the granular material. Dynamic stressing of tectonic faults may play a similar role in determining the complexity of earthquake recurrence. ??2007 Nature Publishing Group.

  20. Effects of acoustic waves on stick-slip in granular media and implications for earthquakes.

    PubMed

    Johnson, Paul A; Savage, Heather; Knuth, Matt; Gomberg, Joan; Marone, Chris

    2008-01-01

    It remains unknown how the small strains induced by seismic waves can trigger earthquakes at large distances, in some cases thousands of kilometres from the triggering earthquake, with failure often occurring long after the waves have passed. Earthquake nucleation is usually observed to take place at depths of 10-20 km, and so static overburden should be large enough to inhibit triggering by seismic-wave stress perturbations. To understand the physics of dynamic triggering better, as well as the influence of dynamic stressing on earthquake recurrence, we have conducted laboratory studies of stick-slip in granular media with and without applied acoustic vibration. Glass beads were used to simulate granular fault zone material, sheared under constant normal stress, and subject to transient or continuous perturbation by acoustic waves. Here we show that small-magnitude failure events, corresponding to triggered aftershocks, occur when applied sound-wave amplitudes exceed several microstrain. These events are frequently delayed or occur as part of a cascade of small events. Vibrations also cause large slip events to be disrupted in time relative to those without wave perturbation. The effects are observed for many large-event cycles after vibrations cease, indicating a strain memory in the granular material. Dynamic stressing of tectonic faults may play a similar role in determining the complexity of earthquake recurrence. PMID:18172496

  1. California earthquake history

    USGS Publications Warehouse

    Toppozada, T.; Branum, D.

    2004-01-01

    This paper presents an overview of the advancement in our knowledge of California's earthquake history since ??? 1800, and especially during the last 30 years. We first review the basic statewide research on earthquake occurrences that was published from 1928 through 2002, to show how the current catalogs and their levels of completeness have evolved with time. Then we review some of the significant new results in specific regions of California, and some of what remains to be done. Since 1850, 167 potentially damaging earthquakes of M ??? 6 or larger have been identified in California and its border regions, indicating an average rate of 1.1 such events per year. Table I lists the earthquakes of M ??? 6 to 6.5 that were also destructive since 1812 in California and its border regions, indicating an average rate of one such event every ??? 5 years. Many of these occurred before 1932 when epicenters and magnitudes started to be determined routinely using seismographs in California. The number of these early earthquakes is probably incomplete in sparsely populated remote parts of California before ??? 1870. For example, 6 of the 7 pre-1873 events in table I are of M ??? 7, suggesting that other earthquakes of M 6.5 to 6.9 occurred but were not properly identified, or were not destructive. The epicenters and magnitudes (M) of the pre-instrumental earthquakes were determined from isoseismal maps that were based on the Modified Mercalli Intensity of shaking (MMI) at the communities that reported feeling the earthquakes. The epicenters were estimated to be in the regions of most intense shaking, and values of M were estimated from the extent of the areas shaken at various MMI levels. MMI VII or greater shaking is the threshold of damage to weak buildings. Certain areas in the regions of Los Angeles, San Francisco, and Eureka were each shaken repeatedly at MMI VII or greater at least six times since ??? 1812, as depicted by Toppozada and Branum (2002, fig. 19).

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

    USGS Publications Warehouse

    2007 Working Group on California Earthquake Probabilities

    2008-01-01

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

  3. Major Existence of Very Low Frequency Earthquakes in Background Seismicity Along Subduction Zone of South-western Japan

    NASA Astrophysics Data System (ADS)

    Ishihara, Y.

    2003-12-01

    The condense, high quality and equalized broadband seismic network provided us to recognize the variety of seismic sources. The active volcanoes excite seismic waves with various frequency characteristics. Some cases show the long period seismic waves greater than 10 sec associates with volcanic activities. The tectonic seismic events originated at the close to trench zone are frequently lack of high frequency, greater than 1 Hz, seismic wave component. Meanwhile, the many low frequency earthquakes and tremors whose sources are not explicated are occurred in lower crust and subcrustal region. The subduction zone of Philippine Sea plate in south-western Japan is actively genetic area of low frequency earthquake group. The broadband seismic array of Japan region observed unknown long period ground motions. The seismograms are higher amplitude between 10 and 30 sec period than ground noise level. The earthquake JMA and USGS catalogues don_ft list about these long period seismograms. The arrival order of wave packet means that these events locate subduction zone around Japan. The hypocenters of unknown events are estimated by arrival times of vertical peak amplitude using the assumption that the ground motion dominates Rayleigh wave. The more detailed determination of major events is performed by combined technique for moment tensor inversion and grid search. The moment magnitude of uncatalogued event is greater than 3.5 because of the detection limitation. The largest event is distributed to about 4.5 Mw level and special event is greater than 5.0. The frequency characteristics show that source time is 7 to 20 sec by comparison with synthetic seismograms. We call these uncatalogued events _gvery low frequency earthquake_h. The hypocenters are located to two kinds of zones along the Philippine Sea subducting plate in south-western Japan. The one zone is very close to the trough. The seismicity listed by earthquake catalogues is low level in the zone and hypocenters are distributed in island arc side. The very low frequency earthquakes occur in outer area of seismic generation zone. The other zone is coincided with extended zone generating low frequency seismic events. Very low frequency earthquake occurs intermittently in limited area. Frequently, activity increases for some days and swarm type activity generates occasionally. To evaluate integrated seismicity for anomalous events, same class magnitude, greater than 3.0, events occurred in same and surrounding area are picked up from JMA earthquake catalogue. The analysis shows that seismicity of very low frequency earthquakes is comparative with one of normal earthquakes in background activity. We concluded that very low frequency earthquake is one of factors playing seismically important role.

  4. Earthquake history of South Carolina

    USGS Publications Warehouse

    von Hake, C. A.

    1976-01-01

    An estimated $23 million damage was caused by one of the great earthquakes in United States history in 1886. Charleston, S.C, and nearby cities suffered most of the damage, although points as far as 160 km away were strongly shaken. Many of the 20 earthquakes of intensity V or greater (Modified Mercalli scale) that centered within South Carolina occurred near Charleston. A 1924 shock in the western part of the State was felt over 145,000 km2. Several earthquakes outside the State borders were felt strongly in South Carolina. 

  5. Large historical earthquakes and tsunamis in a very active tectonic rift: the Gulf of Corinth, Greece

    NASA Astrophysics Data System (ADS)

    Triantafyllou, Ioanna; Papadopoulos, Gerassimos

    2014-05-01

    The Gulf of Corinth is an active tectonic rift controlled by E-W trending normal faults with an uplifted footwall in the south and a subsiding hangingwall with antithetic faulting in the north. Regional geodetic extension rates up to about 1.5 cm/yr have been measured, which is one of the highest for tectonic rifts in the entire Earth, while seismic slip rates up to about 1 cm/yr were estimated. Large earthquakes with magnitudes, M, up to about 7 were historically documented and instrumentally recorded. In this paper we have compiled historical documentation of earthquake and tsunami events occurring in the Corinth Gulf from the antiquity up to the present. The completeness of the events reported improves with time particularly after the 15th century. The majority of tsunamis were caused by earthquake activity although the aseismic landsliding is a relatively frequent agent for tsunami generation in Corinth Gulf. We focus to better understand the process of tsunami generation from earthquakes. To this aim we have considered the elliptical rupture zones of all the strong (M≥ 6.0) historical and instrumental earthquakes known in the Corinth Gulf. We have taken into account rupture zones determined by previous authors. However, magnitudes, M, of historical earthquakes were recalculated from a set of empirical relationships between M and seismic intensity established for earthquakes occurring in Greece during the instrumental era of seismicity. For this application the macroseismic field of each one of the earthquakes was identified and seismic intensities were assigned. Another set of empirical relationships M/L and M/W for instrumentally recorded earthquakes in the Mediterranean region was applied to calculate rupture zone dimensions; where L=rupture zone length, W=rupture zone width. The rupture zones positions were decided on the basis of the localities of the highest seismic intensities and co-seismic ground failures, if any, while the orientation of the maximum axis of the ellipse was determined by following the local fault trends. The tsunami size was calculated in terms of tsunami intensity in the 12-point scale of Papadopoulos-Imamura. We investigated empirical correlations between (i) the tsunami intensity and earthquake magnitude, (ii) the frequency of earthquakes and the frequency of tsunamis, as well as (iii) between the maximum tsunami inundation and the position of the earthquake rupture zone. We discuss our results as for their importance for the development of a tsunami decision matrix in the particular area of Corinth Gulf, an issue which is of interest from the point of view of tsunami early warning.

  6. What caused a large number of fatalities in the Tohoku earthquake?

    NASA Astrophysics Data System (ADS)

    Ando, M.; Ishida, M.; Nishikawa, Y.; Mizuki, C.; Hayashi, Y.

    2012-04-01

    The Mw9.0 earthquake caused 20,000 deaths and missing persons in northeastern Japan. 115 years prior to this event, there were three historical tsunamis that struck the region, one of which is a "tsunami earthquake" resulted with a death toll of 22,000. Since then, numerous breakwaters were constructed along the entire northeastern coasts and tsunami evacuation drills were carried out and hazard maps were distributed to local residents on numerous communities. However, despite the constructions and preparedness efforts, the March 11 Tohoku earthquake caused numerous fatalities. The strong shaking lasted three minutes or longer, thus all residents recognized that this is the strongest and longest earthquake that they had been ever experienced in their lives. The tsunami inundated an enormous area at about 560km2 over 35 cities along the coast of northeast Japan. To find out the reasons behind the high number of fatalities due to the March 11 tsunami, we interviewed 150 tsunami survivors at public evacuation shelters in 7 cities mainly in Iwate prefecture in mid-April and early June 2011. Interviews were done for about 30min or longer focused on their evacuation behaviors and those that they had observed. On the basis of the interviews, we found that residents' decisions not to evacuate immediately were partly due to or influenced by earthquake science results. Below are some of the factors that affected residents' decisions. 1. Earthquake hazard assessments turned out to be incorrect. Expected earthquake magnitudes and resultant hazards in northeastern Japan assessed and publicized by the government were significantly smaller than the actual Tohoku earthquake. 2. Many residents did not receive accurate tsunami warnings. The first tsunami warning were too small compared with the actual tsunami heights. 3. The previous frequent warnings with overestimated tsunami height influenced the behavior of the residents. 4. Many local residents above 55 years old experienced the 1960 Chile tsunami, which was significantly smaller than that of the 11 March tsunami. This sense of "knowing" put their lives at high risk. 5. Some local residents believed that with the presence of a breakwater, only slight flooding would occur. 6. Many people did not understand why tsunami is created under the sea. Therefore, relation of earthquake and tsunami is not quite linked to many people. These interviews made it clear that many deaths resulted because current technology and earthquake science underestimated tsunami heights, warning systems failed, and breakwaters were not strong or high enough. However, even if these problems occur in future earthquakes, better knowledge regarding earthquakes and tsunami hazards could save more lives. In an elementary school when children have fresh brain, it is necessary for them to learn the basic mechanism of tsunami generation.

  7. USGS Training in Afghanistan: Modern Earthquake Hazards Assessments

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

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

  8. Deep Tremor as a Focus of Earthquake Forecasting Research

    NASA Astrophysics Data System (ADS)

    Beroza, G. C.

    2007-12-01

    The discovery of deep tremor has opened a new window into fault-zone processes and offers new possibilities for earthquake forecasting research. Locales where deep tremor has been extensively documented to date include the Nankai Trough, Cascadia, and Central California, which are all areas with considerable seismic potential. Deep tremor is observed to accompany slow slip, such that the combined phenomena have come to be known as episodic tremor and slip (ETS). The emerging view is that deep tremor is the seismic signature of slow slip that occurs episodically on the down-dip extension of seismogenic faults. The amount of slip in these slow slip episodes is approximately equal to the amount of slip that would have been accumulated during the time since the last ETS episode. This suggests that the tremor source may outline the down-dip edge of the locked, seismogenic zone, with the down-dip transition zone locked between ETS episodes, and relaxed during them. Thus, on faults on which tremor occurs, it should be possible to map precisely the down-dip extent of the locked zone, which is often a major source of uncertainty in assessing earthquake potential. Tremor may also prove useful for time-dependent earthquake forecasting. Due to it's strategic location, and episodic nature, deep episodic transients will accelerate stress accumulation on adjacent, shallower, locked portions of faults, which should in turn increase the likelihood of a large earthquake. Thus, tremor is a potentially important forecasting tool, though it might lead to only modest probability gains. With frequent tremor episodes, and infrequent large earthquakes, it will be difficult to test this hypothesis. A more fruitful approach may be to monitor the variation of micro-earthquake activity with respect to deep tremor, and perhaps to examine historical seismic data retrospectively for seismic tremor near the time of large earthquakes. The potential promise of this newly discovered phenomenon argues for enhanced monitoring in areas where tremor is known to occur, and in places where it is likely to occur, based on our understanding of the factors that control tremor occurrence.

  9. Hazard Assessment and Early Warning of Tsunamis: Lessons from the 2011 Tohoku earthquake

    NASA Astrophysics Data System (ADS)

    Satake, K.

    2012-12-01

    The March 11, 2011 Tohoku earthquake (M 9.0) was the largest earthquake in Japanese history, and was the best recorded subduction-zone earthquakes in the world. In particular, various offshore geophysical observations revealed large horizontal and vertical seafloor movements, and the tsunami was recorded on high-quality, high-sampling gauges. Analysis of such tsunami waveforms shows a temporal and spatial slip distribution during the 2011 Tohoku earthquake. The fault rupture started near the hypocenter and propagated into both deep and shallow parts of the plate interface. Very large, ~25 m, slip off Miyagi on the deep part of plate interface corresponds to an interplate earthquake of M 8.8, the location and size similar to 869 Jogan earthquake model, and was responsible for the large tsunami inundation in Sendai and Ishinomaki plains. Huge slip, more than 50 m, occurred on the shallow part near the trench axis ~3 min after the earthquake origin time. This delayed shallow rupture (M 8.8) was similar to the 1896 "tsunami earthquake," and was responsible for the large tsunami on the northern Sanriku coast, measured at ~100 km north of the largest slip. Thus the Tohoku earthquake can be decomposed into an interplate earthquake and the triggered "tsunami earthquake." The Japan Meteorological Agency issued tsunami warning 3 minutes after the earthquake, and saved many lives. However, their initial estimation of tsunami height was underestimated, because the earthquake magnitude was initially estimated as M 7.9, hence the computed tsunami heights were lower. The JMA attempts to improve the tsunami warning system, including technical developments to estimate the earthquake size in a few minutes by using various and redundant information, to deploy and utilize the offshore tsunami observations, and to issue a warning based on the worst case scenario if a possibility of giant earthquake exists. Predicting a trigger of another large earthquake would still be a challenge. Tsunami hazard assessments or long-term forecast of earthquakes have not considered such a triggering or simultaneous occurrence of different types of earthquakes. The large tsunami at the Fukushima nuclear power station was due to the combination of the deep and shallow slip. Disaster prevention for low-frequency but large-scale hazard must be considered. The Japanese government established a general policy to for two levels: L1 and L2. The L2 tsunamis are the largest possible tsunamis with low frequency of occurrence, but cause devastating disaster once they occur. For such events, saving people's lives is the first priority and soft measures such as tsunami hazard maps, evacuation facilities or disaster education will be prepared. The L1 tsunamis are expected to occur more frequently, typically once in a few decades, for which hard countermeasures such as breakwater must be prepared to protect lives and properties of residents as well as economic and industrial activities.

  10. Some clinical characteristics of children who survived the Marmara earthquakes.

    PubMed

    Demir, Turkay; Demir, Demet Eralp; Alkas, Leyla; Copur, Mazlum; Dogangun, Burak; Kayaalp, Levent

    2010-02-01

    The Marmara earthquakes occurred in the Marmara Region (North West) of Turkey in 1999 and resulted in a death toll of approximately 20,000. This paper investigates the relationships between diagnoses and certain variables in children who developed emotional and/or behavioral disturbances in the aftermath of the Marmara earthquakes and were subsequently seen at a child psychiatry outpatient clinic. The variables evaluated are gender, age, the location where the earthquake was experienced, and the degree of losses, bodily injuries, and damage to the residence. Medical records of 321 children and adolescents ranging in age from 2 to 15 years who presented at the clinic due to problems associated with the earthquake between August 1999 and February 2000 were reviewed. Of the patients, 25.5% were diagnosed with post-traumatic stress disorder (PTSD), 16.5% with acute stress disorder (ASD) and 38% with adjustment disorder. No relationship is found between gender and diagnosis. Younger age groups tended to be diagnosed with adjustment disorder. Those who had lost relatives, friends or neighbors were more frequently diagnosed with ASD or PTSD. The same was true for children whose residence was heavily damaged. Children and adolescents constitute the age group that is most severely affected by natural disasters and display significant emotional-behavioral disturbances. The frequency of ASD and PTSD found in our study is considerably high. Although rarely mentioned in the literature, adjustment disorder appears to be one of the most common reactions of children to trauma. PMID:19639383

  11. What Can Sounds Tell Us About Earthquake Interactions?

    NASA Astrophysics Data System (ADS)

    Aiken, C.; Peng, Z.

    2012-12-01

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

  12. Earthquake Scaling, Simulation and Forecasting

    NASA Astrophysics Data System (ADS)

    Sachs, Michael Karl

    Earthquakes are among the most devastating natural events faced by society. In 2011, just two events, the magnitude 6.3 earthquake in Christcurch New Zealand on February 22, and the magnitude 9.0 Tohoku earthquake off the coast of Japan on March 11, caused a combined total of $226 billion in economic losses. Over the last decade, 791,721 deaths were caused by earthquakes. Yet, despite their impact, our ability to accurately predict when earthquakes will occur is limited. This is due, in large part, to the fact that the fault systems that produce earthquakes are non-linear. The result being that very small differences in the systems now result in very big differences in the future, making forecasting difficult. In spite of this, there are patterns that exist in earthquake data. These patterns are often in the form of frequency-magnitude scaling relations that relate the number of smaller events observed to the number of larger events observed. In many cases these scaling relations show consistent behavior over a wide range of scales. This consistency forms the basis of most forecasting techniques. However, the utility of these scaling relations is limited by the size of the earthquake catalogs which, especially in the case of large events, are fairly small and limited to a few 100 years of events. In this dissertation I discuss three areas of earthquake science. The first is an overview of scaling behavior in a variety of complex systems, both models and natural systems. The focus of this area is to understand how this scaling behavior breaks down. The second is a description of the development and testing of an earthquake simulator called Virtual California designed to extend the observed catalog of earthquakes in California. This simulator uses novel techniques borrowed from statistical physics to enable the modeling of large fault systems over long periods of time. The third is an evaluation of existing earthquake forecasts, which focuses on the Regional Earthquake Likelihood Models (RELM) test: the first competitive test of earthquake forecasts in California.

  13. Investigations of Anomalous Earthquakes at Active Volcanoes

    NASA Astrophysics Data System (ADS)

    Shuler, Ashley Elizabeth

    This dissertation investigates the link between volcanic unrest and the occurrence of moderate-to-large earthquakes with a specific type of focal mechanism. Vertical compensated-linear-vector-dipole (vertical-CLVD) earthquakes have vertical pressure or tension axes and seismic radiation patterns that are inconsistent with the double-couple model of slip on a planar fault. Prior to this work, moderate-to-large vertical-CLVD earthquakes were known to be geographically associated with volcanic centers, and vertical-CLVD earthquakes were linked to a tsunami in the Izu-Bonin volcanic arc and a subglacial fissure eruption in Iceland. Vertical-CLVD earthquakes are some of the largest and most anomalous earthquakes to occur in volcanic systems, yet their physical mechanisms remain controversial largely due to the small number of observations. Five vertical-CLVD earthquakes with vertical pressure axes are identified near Nyiragongo volcano in the Democratic Republic of the Congo. Three earthquakes occur within days of a fissure eruption at Nyiragongo, and two occur several years later in association with the refilling of the lava lake in the summit crater of the volcano. Detailed study of these events shows that the earthquakes have slower source processes than tectonic earthquakes with similar magnitudes and locations. All five earthquakes are interpreted as resulting from slip on inward-dipping ring-fault structures located above deflating shallow magma chambers. The Nyiragongo study supports the interpretation that vertical-CLVD earthquakes may be causally related to dynamic physical processes occurring inside the edifices or magmatic plumbing systems of active volcanoes. Two seismicity catalogs from the Global Centroid Moment Tensor (CMT) Project are used to search for further examples of shallow earthquakes with robust vertical-CLVD focal mechanisms. CMT solutions for approximately 400 target earthquakes are calculated and 86 vertical-CLVD earthquakes are identified near active volcanoes. Together with the Nyiragongo study, this work increases the number of well-studied vertical-CLVD earthquakes from 14 to 101. Vertical-CLVD earthquakes have focal depths in the upper ˜10 km of the Earth's crust, and ˜80% have centroid locations within 30 km of an active volcanic center. Vertical-CLVD earthquakes are observed near several different types of volcanoes in a variety of geographic and tectonic settings, but most vertical-CLVD earthquakes are observed near basaltic-to-andesitic stratovolcanoes and submarine volcanoes in subduction zones. Vertical-CLVD earthquakes are linked to tsunamis, volcanic earthquake swarms, effusive and explosive eruptions, and caldera collapse, and approximately 70% are associated with documented volcanic eruptions or episodes of volcanic unrest. Those events with vertical pressure axes typically occur after volcanic eruptions initiate, whereas events with vertical tension axes commonly occur before the start of volcanic unrest. Both types of vertical-CLVD earthquakes have longer source durations than tectonic earthquakes of the same magnitude. The isotropic and pure vertical-CLVD components of the moment tensor cannot be independently resolved using our long-period seismic dataset. As a result, several physical mechanisms can explain the retrieved deviatoric vertical-CLVD moment tensors, including dip-slip motion on ring faults, volume exchange between two reservoirs, the opening and closing of tensile cracks, and volumetric sources. An evaluation of these mechanisms is performed using constraints obtained from detailed studies of individual vertical-CLVD earthquakes. Although no single physical mechanism can explain all of the characteristics of vertical-CLVD earthquakes, a ring-faulting model consisting of slip on inward- or outward-dipping ring faults triggered by the inflation or deflation of a shallow magma chamber can account for their seismic radiation patterns and source durations, as well as their temporal relationships with volcanic unrest. The observation that most vertical-CLVD earthquakes are associated with volcanoes with caldera structures supports this interpretation.

  14. Earthquake history of Nevada

    USGS Publications Warehouse

    von Hake, C. A.

    1974-01-01

    Since 1852, more than 30 shocks of intensity VI or greater (Modified Mercalli scale) have occurred in western Nevada. At least three of these were classified as intensity X. In addition, seven earthquakes (intensity VI or greater) were centered in the eastern part of the State. Almost 2,000 other shocks have been cataloged in the nearly 125-year period of historical records. Thus, Nevada ranks among the most seismically active States. 

  15. Frequent Itemset Hiding Algorithm Using Frequent Pattern Tree Approach

    ERIC Educational Resources Information Center

    Alnatsheh, Rami

    2012-01-01

    A problem that has been the focus of much recent research in privacy preserving data-mining is the frequent itemset hiding (FIH) problem. Identifying itemsets that appear together frequently in customer transactions is a common task in association rule mining. Organizations that share data with business partners may consider some of the frequent…

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2011-10-01

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

  18. Earthquakes and plate tectonics.

    USGS Publications Warehouse

    Spall, H.

    1982-01-01

    Earthquakes occur at the following three kinds of plate boundary: ocean ridges where the plates are pulled apart, margins where the plates scrape past one another, and margins where one plate is thrust under the other. Thus, we can predict the general regions on the earth's surface where we can expect large earthquakes in the future. We know that each year about 140 earthquakes of magnitude 6 or greater will occur within this area which is 10% of the earth's surface. But on a worldwide basis we cannot say with much accuracy when these events will occur. The reason is that the processes in plate tectonics have been going on for millions of years. Averaged over this interval, plate motions amount to several mm per year. But at any instant in geologic time, for example the year 1982, we do not know, exactly where we are in the worldwide cycle of strain build-up and strain release. Only by monitoring the stress and strain in small areas, for instance, the San Andreas fault, in great detail can we hope to predict when renewed activity in that part of the plate tectonics arena is likely to take place. -from Author

  19. Earthquake Testing

    NASA Technical Reports Server (NTRS)

    1979-01-01

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

  20. The physics of an earthquake

    NASA Astrophysics Data System (ADS)

    McCloskey, John

    2008-03-01

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

  1. Predecessors of the giant 1960 Chile earthquake.

    PubMed

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

    2005-09-15

    It is commonly thought that the longer the time since last earthquake, the larger the next earthquake's slip will be. But this logical predictor of earthquake size, unsuccessful for large earthquakes on a strike-slip fault, fails also with the giant 1960 Chile earthquake of magnitude 9.5 (ref. 3). Although the time since the preceding earthquake spanned 123 years (refs 4, 5), the estimated slip in 1960, which occurred on a fault between the Nazca and South American tectonic plates, equalled 250-350 years' worth of the plate motion. Thus the average interval between such giant earthquakes on this fault should span several centuries. Here we present evidence that such long intervals were indeed typical of the last two millennia. We use buried soils and sand layers as records of tectonic subsidence and tsunami inundation at an estuary midway along the 1960 rupture. In these records, the 1960 earthquake ended a recurrence interval that had begun almost four centuries before, with an earthquake documented by Spanish conquistadors in 1575. Two later earthquakes, in 1737 and 1837, produced little if any subsidence or tsunami at the estuary and they therefore probably left the fault partly loaded with accumulated plate motion that the 1960 earthquake then expended. PMID:16163355

  2. Predecessors of the giant 1960 Chile earthquake

    USGS Publications Warehouse

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

    2005-01-01

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

  3. Earthquake tectonics

    SciTech Connect

    Steward, R.F. )

    1991-02-01

    Earthquakes release a tremendous amount of energy into the subsurface in the form of seismic waves. The seismic wave energy of the San Francisco 1906 (M = 8.2) earthquake was equivalent to over 8 billion tons of TNT (3.3 {times} 10{sup 19} joules). Four basic wave types are propagated form seismic sources, two non-rotational and two rotational. As opposed to the non-rotational R and SH waves, the rotational compressional (RC) and rotational shear (RS) waves carry the bulk of the energy from a seismic source. RC wavefronts propagate in the subsurface and refract similarly to P waves, but are considerably slower. RC waves are critically refracted beneath the air surface interface at velocities less than the velocity of sound in air because they refract at the velocity of sound in air minus the retrograde particle velocity at the top of the wave. They propagate at tsunami waves in the open ocean, and produce loud sounds on land that are heard by humans and animals during earthquakes. The energy of the RS wave dwarfs that of the P, SH, and even the RC wave. The RS wave is the same as what is currently called the S wave in earthquake seismology, and produces both folding and strike-slip faulting at considerable distances from the epicenter. RC and RS waves, propagated during earthquakes from the Santa Ynez fault and a right-slip fault on trend with the Red Mountain fault, produced the Santa Ynez Mountains in California beginning in the middle Pliocene and continuing until the present.

  4. Mapping Tectonic Stress Using Earthquakes

    SciTech Connect

    Arnold, Richard; Townend, John; Vignaux, Tony

    2005-11-23

    An earthquakes occurs when the forces acting on a fault overcome its intrinsic strength and cause it to slip abruptly. Understanding more specifically why earthquakes occur at particular locations and times is complicated because in many cases we do not know what these forces actually are, or indeed what processes ultimately trigger slip. The goal of this study is to develop, test, and implement a Bayesian method of reliably determining tectonic stresses using the most abundant stress gauges available - earthquakes themselves.Existing algorithms produce reasonable estimates of the principal stress directions, but yield unreliable error bounds as a consequence of the generally weak constraint on stress imposed by any single earthquake, observational errors, and an unavoidable ambiguity between the fault normal and the slip vector.A statistical treatment of the problem can take into account observational errors, combine data from multiple earthquakes in a consistent manner, and provide realistic error bounds on the estimated principal stress directions.We have developed a realistic physical framework for modelling multiple earthquakes and show how the strong physical and geometrical constraints present in this problem allow inference to be made about the orientation of the principal axes of stress in the earth's crust.

  5. Two models for earthquake forerunners

    USGS Publications Warehouse

    Mjachkin, V.I.; Brace, W.F.; Sobolev, G.A.; Dieterich, J.H.

    1975-01-01

    Similar precursory phenomena have been observed before earthquakes in the United States, the Soviet Union, Japan, and China. Two quite different physical models are used to explain these phenomena. According to a model developed by US seismologists, the so-called dilatancy diffusion model, the earthquake occurs near maximum stress, following a period of dilatant crack expansion. Diffusion of water in and out of the dilatant volume is required to explain the recovery of seismic velocity before the earthquake. According to a model developed by Soviet scientists growth of cracks is also involved but diffusion of water in and out of the focal region is not required. With this model, the earthquake is assumed to occur during a period of falling stress and recovery of velocity here is due to crack closure as stress relaxes. In general, the dilatancy diffusion model gives a peaked precursor form, whereas the dry model gives a bay form, in which recovery is well under way before the earthquake. A number of field observations should help to distinguish between the two models: study of post-earthquake recovery, time variation of stress and pore pressure in the focal region, the occurrence of pre-existing faults, and any changes in direction of precursory phenomena during the anomalous period. ?? 1975 Birkha??user Verlag.

  6. Utilizing Changes in Repeating Earthquakes to Monitor Evolving Processes and Structure Before and During Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    Hotovec-Ellis, Alicia

    Repeating earthquakes are two or more earthquakes that share the same source location and source mechanism, which results in the earthquakes having highly similar waveforms when recorded at a seismic instrument. Repeating earthquakes have been observed in a wide variety of environments: from fault systems (such as the San Andreas and Cascadia subduction zone), to hydrothermal areas and volcanoes. Volcano seismologists are particularly concerned with repeating earthquakes, as they have been observed at volcanoes along the entire range of eruptive style and are often a prominent feature of eruption seismicity. The behavior of repeating earthquakes sometimes changes with time, which possibly reflects subtle changes in the mechanism creating the earthquakes. In Chapter 1, we document an example of repeating earthquakes during the 2009 eruption of Redoubt volcano that became increasingly frequent with time, until they blended into harmonic tremor prior to several explosions. We interpreted the source of the earthquakes as stick-slip on a fault near the conduit that slipped increasingly often as the explosion neared in response to the build-up of pressure in the system. The waveforms of repeating earthquakes may also change, even if the behavior does not. We can quantify changes in waveform using the technique of coda wave interferometry to differentiate between changes in source and medium. In Chapters 2 and 3, we document subtle changes in the coda of repeating earthquakes related to small changes in the near-surface velocity structure at Mount St. Helens before and during its eruption in 2004. Velocity changes have been observed prior to several volcanic eruptions, are thought to occur in response to volumetric strain and the opening or closing of cracks in the subsurface. We compared continuous records of velocity change against other geophysical data, and found that velocities at Mount St. Helens change in response to snow loading, fluid saturation, shaking from large distant earthquakes, shallow pressurization, and possibly lava extrusion. Velocity changes at Mount St. Helens are a complex mix of many different effects, and other complementary data are required to interpret the signal.

  7. The next new Madrid earthquake

    SciTech Connect

    Atkinson, W.

    1988-01-01

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

  8. Advances in Earthquake Prediction Research and the June 2000 Earthquakes in Iceland

    NASA Astrophysics Data System (ADS)

    Stefansson, R.

    2006-12-01

    In June 2000, two earthquakes with magnitude 6.6 (Ms) occurred in the central part of the South Iceland seismic zone (SISZ). Earthquakes in this region have, according to historical information, in some cases caused collapse of the majority of houses in areas encompassing 1,000 square kilometers in this relatively densely populated farming region. Because large earthquakes were expected to occur soon, much attention was given to preparedness in the region and for the last two decades it has been the subject of multi- national, mainly European, co-operation in earthquake prediction research and in the development of a high- level micro-earthquake system: the SIL system. Despite intensive surface fissuring caused by the earthquakes and measured accelerations reaching 0.8 g, the earthquakes in 2000 caused no serious injuries and no structural collapse. The relatively minor destruction led to more optimism regarding the safety of living in the area. But it also lead to some optimism about the significance of earthquake prediction research. Both earthquakes had a long-term prediction and the second of the two earthquakes had a short- term warning about place, size and immediacy. In this presentation, I will describe the warnings that were given ahead of the earthquakes. Also, I will reconsider these warnings in light of new results from multi-national earthquake prediction research in Iceland. This modeling work explains several observable patterns caused by crustal process ahead of large earthquakes. Micro-seismic observations and modeling show that, in conditions prevailing in the Icelandic crust, fluids can be carried upward from the brittle-ductile boundary in response to strain, bringing high, near- lithostatic pore pressures into the brittle crust, preparing a region for the release of a large earthquake; monitoring this process will enable long- and short- term earthquakes warnings.

  9. Long Period Earthquakes Beneath California's Young and Restless Volcanoes

    NASA Astrophysics Data System (ADS)

    Pitt, A. M.; Dawson, P. B.; Shelly, D. R.; Hill, D. P.; Mangan, M.

    2013-12-01

    The newly established USGS California Volcano Observatory has the broad responsibility of monitoring and assessing hazards at California's potentially threatening volcanoes, most notably Mount Shasta, Medicine Lake, Clear Lake Volcanic Field, and Lassen Volcanic Center in northern California; and Long Valley Caldera, Mammoth Mountain, and Mono-Inyo Craters in east-central California. Volcanic eruptions occur in California about as frequently as the largest San Andreas Fault Zone earthquakes-more than ten eruptions have occurred in the last 1,000 years, most recently at Lassen Peak (1666 C.E. and 1914-1917 C.E.) and Mono-Inyo Craters (c. 1700 C.E.). The Long Valley region (Long Valley caldera and Mammoth Mountain) underwent several episodes of heightened unrest over the last three decades, including intense swarms of volcano-tectonic (VT) earthquakes, rapid caldera uplift, and hazardous CO2 emissions. Both Medicine Lake and Lassen are subsiding at appreciable rates, and along with Clear Lake, Long Valley Caldera, and Mammoth Mountain, sporadically experience long period (LP) earthquakes related to migration of magmatic or hydrothermal fluids. Worldwide, the last two decades have shown the importance of tracking LP earthquakes beneath young volcanic systems, as they often provide indication of impending unrest or eruption. Herein we document the occurrence of LP earthquakes at several of California's young volcanoes, updating a previous study published in Pitt et al., 2002, SRL. All events were detected and located using data from stations within the Northern California Seismic Network (NCSN). Event detection was spatially and temporally uneven across the NCSN in the 1980s and 1990s, but additional stations, adoption of the Earthworm processing system, and heightened vigilance by seismologists have improved the catalog over the last decade. LP earthquakes are now relatively well-recorded under Lassen (~150 events since 2000), Clear Lake (~60 events), Mammoth Mountain (~320 events), and Long Valley Caldera (~40 events). LP earthquakes are notably absent under Mount Shasta. With the exception of Long Valley Caldera where LP earthquakes occur at depths of ≤5 km, hypocenters are generally between 15-25 km. The rates of LP occurrence over the last decade have been relatively steady within the study areas, except at Mammoth Mountain, where years of gradually declining LP activity abruptly increased after a swarm of unusually deep (20 km) VT earthquakes in October 2012. Epicenter locations relative to the sites of most recent volcanism vary across volcanic centers, but most LP earthquakes fall within 10 km of young vents. Source models for LP earthquakes often involve the resonance of fluid-filled cracks or nonlinear flow of fluids along irregular cracks (reviewed in Chouet and Matoza, 2013, JVGR). At mid-crustal depths the relevant fluids are likely to be low-viscosity basaltic melt and/or exsolved CO2-rich volatiles (Lassen, Clear Lake, Mammoth Mountain). In the shallow crust, however, hydrothermal waters/gases are likely involved in the generation of LP seismicity (Long Valley Caldera).

  10. America's faulty earthquake plans

    SciTech Connect

    Rosen, J

    1989-10-01

    In this article, the author discusses the liklihood of major earthquakes in both the western and eastern United States as well as the level of preparedness of each region of the U.S. for a major earthquake. Current technology in both earthquake-resistance design and earthquake detection is described. Governmental programs for earthquake hazard reduction are outlined and critiqued.

  11. Earthquakes triggered by fluid extraction

    USGS Publications Warehouse

    Segall, P.

    1989-01-01

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

  12. Scabies: Frequently Asked Questions (FAQs)

    MedlinePlus

    ... CDC.gov . Parasites - Scabies Parasites Home Share Compartir Scabies Frequently Asked Questions (FAQs) On this Page What ... has scabies, should I treat myself? What is scabies? Scabies is an infestation of the skin by ...

  13. Luzon earthquake strongest in 90 years

    NASA Astrophysics Data System (ADS)

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

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

    USGS Publications Warehouse

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

    2011-01-01

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

  15. Earthquakes at North Atlantic passive margins

    SciTech Connect

    Gregersen, S. ); Basham, P.W. )

    1989-01-01

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

  16. Evidence for Ancient Mesoamerican Earthquakes

    NASA Astrophysics Data System (ADS)

    Kovach, R. L.; Garcia, B.

    2001-12-01

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

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    PubMed

    Satake, Kenji

    2015-10-28

    Great (M∼8) earthquakes repeatedly occur along the subduction zones around Japan and cause fault slip of a few to several metres releasing strains accumulated from decades to centuries of plate motions. Assuming a simple 'characteristic earthquake' model that similar earthquakes repeat at regular intervals, probabilities of future earthquake occurrence have been calculated by a government committee. However, recent studies on past earthquakes including geological traces from giant (M∼9) earthquakes indicate a variety of size and recurrence interval of interplate earthquakes. Along the Kuril Trench off Hokkaido, limited historical records indicate that average recurrence interval of great earthquakes is approximately 100 years, but the tsunami deposits show that giant earthquakes occurred at a much longer interval of approximately 400 years. Along the Japan Trench off northern Honshu, recurrence of giant earthquakes similar to the 2011 Tohoku earthquake with an interval of approximately 600 years is inferred from historical records and tsunami deposits. Along the Sagami Trough near Tokyo, two types of Kanto earthquakes with recurrence interval of a few hundred years and a few thousand years had been recognized, but studies show that the recent three Kanto earthquakes had different source extents. Along the Nankai Trough off western Japan, recurrence of great earthquakes with an interval of approximately 100 years has been identified from historical literature, but tsunami deposits indicate that the sizes of the recurrent earthquakes are variable. Such variability makes it difficult to apply a simple 'characteristic earthquake' model for the long-term forecast, and several attempts such as use of geological data for the evaluation of future earthquake probabilities or the estimation of maximum earthquake size in each subduction zone are being conducted by government committees. PMID:26392616

  19. Mitigating mass movement caused by earthquakes and typhoons: a case study of central Taiwan

    NASA Astrophysics Data System (ADS)

    Lin, Jiun-Chuan

    2013-04-01

    Typhoons caused huge damages to Taiwan at the average of 3.8 times a year in the last 100 years, according to Central Weather Bureau data. After the Chi-Chi earthquake of 1999 at the magnitude of Richard Scale 7.3, typhoons with huge rainfall would cause huge debris flow and deposits at river channels. As a result of earthquakes, loose debris falls and flows became significant hazards in central Taiwan. Analysis of rainfall data and data about the sites of slope failure show that damage from natural hazards was enhanced in the last 20 years, as a result of the Chi-Chi earthquake. There are three main types of mass movement in Central Taiwan: landslides, debris flows and gully erosion. Landslides occurred mainly along hill slopes and river channel banks. Many dams, check dams, housing structures and even river channels can be raised to as high as 60 meters as a result of stacking up floating materials of landslides. Debris flows occurred mainly through typhoon periods and activated ancient debris deposition. New gullies were thus developed from deposits loosened and shaken up by earthquakes. Extreme earthquakes and typhoon events occurred frequently in the last 20 years. This paper analyzes the geological and geomorphologic background for the precarious areas and typhoons in central Taiwan, to make a systematic understanding of mass movement harzards. The mechanism and relations of debris flows and rainfall data in central Taiwan are analyzed. Ways for mitigating mass movement threats are also proposed in this paper. Keywords: mass movement, earthquakes, typhoons, hazard mitigation, central Ta

  20. Earthquake Swarms Near the Northern End of the Calaveras Fault

    NASA Astrophysics Data System (ADS)

    Walter, S.; Schwartz, D.

    2008-12-01

    The Calaveras fault splays off the San Andreas fault near the Pinnacles National Monument in central California and extends northward over 160 km into the San Francisco Bay area where it apparently ends near the town of Danville. While the southern and central Calaveras creep at a high rate of about 14 mm/yr and produce frequent small and moderate earthquakes, the northern Calaveras fault is basically locked with only minor creep and little or no seismicity. The northern Calaveras has not produced a large earthquake in over 300 years. Earthquake probability estimates for the Calaveras fault are 10-11% for a M6.7 or larger within the next 30 years, with the highest probability on the northern Calaveras. The San Ramon Valley adjacent to the northern Calaveras fault is the locus of earthquake swarm activity in the Bay Area. Five notable swarms have occurred there during the past 35 years. These swarms: 1) are primarily located to the east and northeast of the Calaveras in a section of crust bounded on the east by the Mt. Diablo blind thrust and the Concord-Green Valley fault ; 2) do not exhibit a mainshock-aftershock pattern as the largest event may occur later in the sequence; 3) have depths limited to about 8 km, and 4) are not aligned with the dominant NW-SE trend of most faults in the Bay Area and in at least two cases trend orthogonally to the Calaveras fault. The most well developed of these swarms was the Alamo swarm that began in April, 1990 and produced 351 earthquakes over 42 days. It included four M4 events, two of which occurred later in the sequence. The swarm defined a linear fault patch nearly 6 km long extending east-northeast from the northern end of the Calaveras fault, with seismicity between depths of 5-9 km. Left-lateral, strike-slip focal mechanisms for the larger events aligned well with the trend of the swarm. The earthquake swarm activity in the San Ramon Valley reflects deformation of a structurally complex block responding to the transfer of slip from the Calaveras to the Concord-Green Valley fault.

  1. Intraplate triggered earthquakes: Observations and interpretation

    USGS Publications Warehouse

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

    2003-01-01

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

  2. Identified EM Earthquake Precursors

    NASA Astrophysics Data System (ADS)

    Jones, Kenneth, II; Saxton, Patrick

    2014-05-01

    Many attempts have been made to determine a sound forecasting method regarding earthquakes and warn the public in turn. Presently, the animal kingdom leads the precursor list alluding to a transmission related source. By applying the animal-based model to an electromagnetic (EM) wave model, various hypotheses were formed, but the most interesting one required the use of a magnetometer with a differing design and geometry. To date, numerous, high-end magnetometers have been in use in close proximity to fault zones for potential earthquake forecasting; however, something is still amiss. The problem still resides with what exactly is forecastable and the investigating direction of EM. After a number of custom rock experiments, two hypotheses were formed which could answer the EM wave model. The first hypothesis concerned a sufficient and continuous electron movement either by surface or penetrative flow, and the second regarded a novel approach to radio transmission. Electron flow along fracture surfaces was determined to be inadequate in creating strong EM fields, because rock has a very high electrical resistance making it a high quality insulator. Penetrative flow could not be corroborated as well, because it was discovered that rock was absorbing and confining electrons to a very thin skin depth. Radio wave transmission and detection worked with every single test administered. This hypothesis was reviewed for propagating, long-wave generation with sufficient amplitude, and the capability of penetrating solid rock. Additionally, fracture spaces, either air or ion-filled, can facilitate this concept from great depths and allow for surficial detection. A few propagating precursor signals have been detected in the field occurring with associated phases using custom-built loop antennae. Field testing was conducted in Southern California from 2006-2011, and outside the NE Texas town of Timpson in February, 2013. The antennae have mobility and observations were noted for recurrence, duration, and frequency response. At the Southern California field sites, one loop antenna was positioned for omni-directional reception and also detected a strong First Schumann Resonance; however, additional Schumann Resonances were absent. At the Timpson, TX field sites, loop antennae were positioned for directional reception, due to earthquake-induced, hydraulic fracturing activity currently conducted by the oil and gas industry. Two strong signals, one moderately strong signal, and approximately 6-8 weaker signals were detected in the immediate vicinity. The three stronger signals were mapped by a biangulation technique, followed by a triangulation technique for confirmation. This was the first antenna mapping technique ever performed for determining possible earthquake epicenters. Six and a half months later, Timpson experienced two M4 (M4.1 and M4.3) earthquakes on September 2, 2013 followed by a M2.4 earthquake three days later, all occurring at a depth of five kilometers. The Timpson earthquake activity now has a cyclical rate and a forecast was given to the proper authorities. As a result, the Southern California and Timpson, TX field results led to an improved design and construction of a third prototype antenna. With a loop antenna array, a viable communication system, and continuous monitoring, a full fracture cycle can be established and observed in real-time. In addition, field data could be reviewed quickly for assessment and lead to a much more improved earthquake forecasting capability. The EM precursors determined by this method appear to surpass all prior precursor claims, and the general public will finally receive long overdue forecasting.

  3. The Most Frequent English Homonyms

    ERIC Educational Resources Information Center

    Parent, Kevin

    2012-01-01

    This article distinguishes homonymy, homophony, homography and polysemy, and provides a list of the most frequent homonyms using corpus-derived data. For most of the homonyms, the most common meaning accounts for 90% or more of the total uses of the form. The pedagogical and research implications of these findings are discussed. (Contains 5…

  4. Earthquake history of New Mexico

    USGS Publications Warehouse

    von Hake, C. A.

    1975-01-01

    Most of New Mexico's historical seismcity has been concentrated in the Rio Grande Valley between Socorro and Albuquerque. About half of the earthquakes of intensity V or greater (Modified Mercalli intensity) that occurred in teh State between 1868 and 1973 were centered in this region. 

  5. Why so few? Landslides triggered by the 2002 Denali earthquake, Alaska

    NASA Astrophysics Data System (ADS)

    Gorum, Tolga; Korup, Oliver; van Westen, Cees J.; van der Meijde, Mark; Xu, Chong; van der Meer, Freek D.

    2014-07-01

    The 2002 Mw 7.9 Denali Fault earthquake, Alaska, provides an unparalleled opportunity to investigate in quantitative detail the regional hillslope mass-wasting response to strong seismic shaking in glacierized terrain. We present the first detailed inventory of ?1580 coseismic slope failures, out of which some 20% occurred above large valley glaciers, based on mapping from multi-temporal remote sensing data. We find that the Denali earthquake produced at least one order of magnitude fewer landslides in a much narrower corridor along the fault ruptures than empirical predictions for an M ?8 earthquake would suggest, despite the availability of sufficiently steep and dissected mountainous topography prone to frequent slope failure. In order to explore potential controls on the reduced extent of regional coseismic landsliding we compare our data with inventories that we compiled for two recent earthquakes in periglacial and formerly glaciated terrain, i.e. at Yushu, Tibet (Mw 6.9, 2010), and Aysn Fjord, Chile (2007 Mw 6.2). Fault movement during these events was, similarly to that of the Denali earthquake, dominated by strike-slip offsets along near-vertical faults. Our comparison returns very similar coseismic landslide patterns that are consistent with the idea that fault type, geometry, and dynamic rupture process rather than widespread glacier cover were among the first-order controls on regional hillslope erosional response in these earthquakes. We conclude that estimating the amount of coseismic hillslope sediment input to the sediment cascade from earthquake magnitude alone remains highly problematic, particularly if glacierized terrain is involved.

  6. Earthquake swarms reveal submarine magma unrest induced by distant mega-earthquakes: Andaman Sea region

    NASA Astrophysics Data System (ADS)

    Špičák, Aleš; Vaněk, Jiří

    2016-02-01

    Little is known about earthquake-triggered magma intrusions or eruptions of submarine volcanoes. The analysis of teleseismic earthquake occurrence performed in this study offers a tool to address such enigmatic and inaccessible processes. In the past ten years, the Andaman Sea region repeatedly became a site of shallow earthquake swarms that followed distant mega-earthquakes by days to weeks. The MW 9.1 December 26, 2004 Sumatra-Andaman earthquake was followed by two earthquake swarms about 600 km northward in the Andaman Sea region, delayed by 30 and 35 days, respectively. Earthquakes of one of these seismic episodes, the extensive January 2005 earthquake swarm, migrated laterally at a rate of about 0.25 km per hour during the swarm evolution. The strong Indian Ocean MW 8.6 and 8.2 April 11, 2012 earthquake doublet west of Northern Sumatra was followed by an earthquake swarm approximately 800 km northward in the Andaman Sea region, delayed by 13 days. All the three swarms that followed the 2004 and 2012 mega-earthquakes occurred beneath distinct seamounts and seafloor ridges. Based on the observations of migration of earthquakes during the swarm and swarm occurrence beneath distinct highs at the seafloor, we conclude that these earthquake swarms probably resulted as a consequence of magma unrest induced by static and/or dynamic stress changes following the distant mega-earthquakes. Repeated occurrence of such a phenomenon suggests that the arc magma reservoirs beneath the Andaman Sea have recently reached some form of criticality and are vulnerable to even small stress changes. The Andaman seafloor could thus become a site of submarine volcanic eruptions in near future and deserves close attention of Earth scientists.

  7. Meeting focuses on catastrophic Asian earthquakes

    NASA Astrophysics Data System (ADS)

    Gupta, Harsh K.

    The International Association of Seismology and Physics of the Earth's Interior (IAS-PEI) and the Asian Seismological Commission met August 1-3, 1996, in Tangshan, China. Twenty years ago, Tangshan was destroyed by the century's worst earthquake, which killed an estimated 243,000 people.It was the first meeting of the Asian Seismological Commission (ASC), a group formed in 1995 by the IASPEI umbrella, to improve understanding of geological processes in Asia and to mitigate earthquake disasters. Because of its widespread seismic activity, the vast, populated territory of Asia has more catastrophic earthquakes than other regions of the world (see Figure 1). During the period from 1892 to 1992, 50 percent of the world's major earthquakes (magnitude greater than 8) occurred in Asia and the Southern Pacific region. Economic losses of more than $100 billion from the most recent major Asian earthquake that occurred in Kobe, Japan, in early 1995, make Kobe the most expensive earthquake in the world. In September 1993, the Latur earthquake in the stable shield region of southern India claimed 10,000 lives, and although of only 6.1 magnitude, was the deadliest stable continental region earthquake.

  8. Earthquake hazards on the cascadia subduction zone.

    PubMed

    Heaton, T H; Hartzell, S H

    1987-04-10

    Large subduction earthquakes on the Cascadia subduction zone pose a potential seismic hazard. Very young oceanic lithosphere (10 million years old) is being subducted beneath North America at a rate of approximately 4 centimeters per year. The Cascadia subduction zone shares many characteristics with subduction zones in southern Chile, southwestern Japan, and Colombia, where comparably young oceanic lithosphere is also subducting. Very large subduction earthquakes, ranging in energy magnitude (M(w)) between 8 and 9.5, have occurred along these other subduction zones. If the Cascadia subduction zone is also storing elastic energy, a sequence of several great earthquakes (M(w) 8) or a giant earthquake (M(w) 9) would be necessary to fill this 1200-kilometer gap. The nature of strong ground motions recorded during subduction earthquakes of M(w) less than 8.2 is discussed. Strong ground motions from even larger earthquakes (M(w) up to 9.5) are estimated by simple simulations. If large subduction earthquakes occur in the Pacific Northwest, relatively strong shaking can be expected over a large region. Such earthquakes may also be accompanied by large local tsunamis. PMID:17789780

  9. Earthquake hazards on the cascadia subduction zone

    SciTech Connect

    Heaton, T.H.; Hartzell, S.H.

    1987-04-10

    Large subduction earthquakes on the Cascadia subduction zone pose a potential seismic hazard. Very young oceanic lithosphere (10 million years old) is being subducted beneath North America at a rate of approximately 4 centimeters per year. The Cascadia subduction zone shares many characteristics with subduction zones in southern Chile, southwestern Japan, and Colombia, where comparably young oceanic lithosphere is also subducting. Very large subduction earthquakes, ranging in energy magnitude (M/sub w/) between 8 and 9.5, have occurred along these other subduction zones. If the Cascadia subduction zone is also storing elastic energy, a sequence of several great earthquakes (M/sub w/ 8) or a giant earthquake (M/sub w/ 9) would be necessary to fill this 1200-kilometer gap. The nature of strong ground motions recorded during subduction earthquakes of M/sub w/ less than 8.2 is discussed. Strong ground motions from even larger earthquakes (M/sub w/ up to 9.5) are estimated by simple simulations. If large subduction earthquakes occur in the Pacific Northwest, relatively strong shaking can be expected over a large region. Such earthquakes may also be accompanied by large local tsunamis. 35 references, 6 figures.

  10. Observed Weather Satellite Thermal IR Responses Prior to Earthquakes

    NASA Astrophysics Data System (ADS)

    Bryant, N. A.; Zobrist, A. L.; Logan, L. L.; Freund, F.; Nishenko, S.

    2002-12-01

    A number of observers claim to have seen thermal anomalies prior to earthquakes, but subsequent analysis by others have failed to produce similar findings. It was the purpose of this study to determine if thermal anomalies could be found in association with known earthquakes by systematically co-registering weather satellite images at the sub-pixel level and then determining if statistically significant responses had occurred prior to an event. Earthquakes associated with plate movement (strike-slip and thrust faulting), rather than volcanism, were to be considered. A new set of automatic co-registration procedures were developed for this task to accommodate all properties particular to weather satellite observations taken at night. Spacecraft and sensor ephemeris and the horizontal displacement due to elevation were all factored in, and final adjustment for minor satellite deviations (related to roll, pitch, and yaw) were made by using image-to-image tiepoint correlations. Reliance upon visual clues in an image (frequently the subject of debate in the past) is not required. The technique relies on the general condition where ground cools after sunset. The technique applies best to the use of the geosynchronous weather satellites (GOES, Meteosat, and GMS), where images are taken every thirty minutes. Use of the geosynchronous satellites also reduces the potential for miscalculation of trends due to weather front movement or local cloud/fog formation. The polar orbiting satellites have better resolution (1km vs 5km) and better signal-to-noise, but only acquire images twice during an evening, thereby making trend analysis difficult. Case studies investigated to date include the Hector Mine California and Ikrit Turkey earthquakes of 1999, and the Bhuj India quake of 2001. The result of the new analytic procedures has been the observance of apparent heating trends close to epicenters in satellite data acquisitions a few hours prior to an earthquake. When observations along known fault-lines showed a much-reduced `temperature' decline through the evening, or in some cases an actual `temperature' increase, an earthquake occurred. This result may indicate mid-infrared luminescence associated with crustal deformation(Freund, 2002), rather than heat emission. Other events are currently under investigation using the methods developed.

  11. Reactivation of an oblique transfer fault during the Chi-Chi earthquake

    NASA Astrophysics Data System (ADS)

    Rau, R.; Byrne, T.; Lee, Y.

    2008-12-01

    Recognition of buried, deep-seated fault zones is important in earthquake potential assessment because such structures are often blind or have little surface expression, yet they may be hazardous once activated. We examine seismicity between 1991 and 2003 along one of the 1999 M 7.6 Chi-Chi earthquake aftershock regions south of the Chi-Chi source zone to study the reactivation of a previously unrecognized structure within the Taiwan arc-continent collision zone. More than 6000 M > 3 Chi-Chi aftershocks up to August 2003 occurred both on and off the Chi-Chi rupture zone, which terminates in the south by a NNW-SSE- trending cluster of earthquakes dominated by left-lateral focal mechanisms, hereafter called Luliao seismic sequence. We use earthquake locations resulting from the 3D tomographic inversion and compute earthquake fault-plane solutions using P wave first motions and SH/P amplitude ratios. We found that thrust, normal and strike-slip events occur in all timeframes, but during Chi-Chi (and about 6 months after) left- lateral mechanisms much more frequent. For the general kinematic patterns, thrust faults dominantly occur in two areas - northern and southern ends of the cluster, and are generally consistent with the surface geology. Normal fault mechanisms occur throughout the Luliao seismic zone and consistently show south- southwest extension on high-angle fault planes. The geometry and kinematics of these structures are also consistent with geologic patterns - mapped normal faults trend east-southeast, suggesting that the seismicity records one phase of the geologic history. Strike-slip mechanisms form well-defined curvilinear map trace suggesting a single regional-scale structure. The limited evidence for surface displacements, however, suggests that the fault is blind or that the fault has had a more limited slip history. We consider the possibility that the Luliao seismic zone reactivated an older structure possibly inherited from the colliding Chinese continental margin.

  12. Earthquake occurrence and effects.

    PubMed

    Adams, R D

    1990-01-01

    Although earthquakes are mainly concentrated in zones close to boundaries of tectonic plates of the Earth's lithosphere, infrequent events away from the main seismic regions can cause major disasters. The major cause of damage and injury following earthquakes is elastic vibration, rather than fault displacement. This vibration at a particular site will depend not only on the size and distance of the earthquake but also on the local soil conditions. Earthquake prediction is not yet generally fruitful in avoiding earthquake disasters, but much useful planning to reduce earthquake effects can be done by studying the general earthquake hazard in an area, and taking some simple precautions. PMID:2347628

  13. Earthquake and Tsunami booklet based on two Indonesia earthquakes

    NASA Astrophysics Data System (ADS)

    Hayashi, Y.; Aci, M.

    2014-12-01

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

  14. The 8 February 1843 Lesser Antilles Earthquake: A "Missing" Great Earthquake

    NASA Astrophysics Data System (ADS)

    Hough, S. E.

    2012-12-01

    The seismic potential of the Lesser Antilles subduction zone and the adjacent Puerto Rico trench remains a matter of debate. The central arc of the Lesser Antilles subduction zone is currently accumulating elastic strain at a rate slower than the plate motion (Manaker et al., 2008), and a recent study concludes that no major subduction zone earthquake has occurred along the Puerto Rico trench during the 500-year historical record (tenBrink et al., 2012). The 8 February 1843 earthquake is the largest historical event on the Lesser Antilles arc. A recent study estimated a preferred magnitude of 8.5 based on near-field macroseismic effects (Feuillet et al., 2011), but the generally accepted value has been 7.5-8. A consideration of the regional and far-field macroseismic effects reveals a felt distribution comparable to those of recent great (Mw ≥ 9.0) earthquakes. Credible archival accounts provide compelling evidence that the earthquake was felt throughout a wide region of the eastern United States, as far north as New York City. The event was also felt at three locations in South America, and in Bermuda. A modest tsunami is described by two witnesses; two other accounts describe uplift of a stone wharf in Antigua, and along the northern coast of Guadaloupe . The distribution and character of intensities in the near field of any earthquake will reflect the complexity of the source; the pattern of high- and low-frequency radiation from the 2011 Tohoku, Japan, earthquake, demonstrates that these patterns can be complex for great earthquakes. For the 1843 earthquake, the far-field intensity distribution provides a stronger constraint on magnitude. The observations support the inference of a high (M≥8.5) magnitude, and significant moment release towards or possibly around the northern corner of the Lesser Antilles Arc. Possible modern analogs for such an event can be identified, including the Mw8.6 2005 Nias earthquake and the 11 April 2012 Mw8.6 strike-slip earthquake off Sumatra. Further re-examination of the global catalog of earthquakes during the historical era suggests that the magnitudes of some great historical earthquakes have been underestimated, with approximately half of all Mw≥8.5 earthquakes missing or underestimated in the 19th century. Since very large magnitudes are generally inferred for historical earthquakes based on tsunami wave heights, magnitudes would tend to be underestimated for deeper subduction earthquakes that generated small tsunamis, earthquakes that produced tsunamis that were not documented, and strike-slip earthquakes such as the 11 April 2012 Sumatra event. The 1843 Lesser Antilles earthquake emerges as a prime candidate for a "missing" great earthquake.

  15. Development of Tools for the Rapid Assessment of Landslide Potential in Areas Exposed to Intense Storms, Earthquakes, and Other Triggering Mechanisms

    NASA Astrophysics Data System (ADS)

    Highland, Lynn

    2014-05-01

    Landslides frequently occur in connection with other types of hazardous phenomena such as earthquake or volcanic activity and intense rainstorms. Strong shaking, for example, often triggers extensive landslides in mountainous areas, which can then complicate response and compound socio-economic impacts over shaking losses alone. The U.S. Geological Survey (USGS) is exploring different ways to add secondary hazards to its Prompt Assessment of Global Earthquakes for Response (PAGER) system, which has been developed to deliver rapid earthquake impact and loss assessments following significant global earthquakes. The PAGER team found that about 22 percent of earthquakes with fatalities have deaths due to secondary causes, and the percentage of economic losses they incur has not been widely studied, but is probably significant. The current approach for rapid assessment and reporting of the potential and distribution of secondary earthquake-induced landslides involves empirical models that consider ground acceleration, slope, and rock-strength. A complementary situational awareness tool being developed is a region-specific landslide database for the U.S. The latter will be able to define, in a narrative form, the landslide types (debris flows, rock avalanches, shallow versus deep) that generally occur in each area, along with the type of soils, geology and meteorological effects that could have a bearing on soil saturation, and thus susceptibility. When a seismic event occurs in the U.S. and the PAGER system generates web-based earthquake information, these landslide narratives will simultaneously be made available, which will help in the assessment of the nature of landslides in that particular region. This landslide profile database could also be applied to landslide events that are not triggered by earthquake shaking, in conjunction with National Weather Service Alerts and other landslide/debris-flow alerting systems. Currently, prototypes are being developed for both the slope-based and the narrative assessment of landslide susceptibility and hazard.

  16. Earthquake research needed in California

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    According to an analysis by a group of seismologists and tectonophysicists from the Lamont-Doherty Geological Observatory of Columbia University and the Seismological Laboratory of the California Institute of Technology, there is an imperative need for extensive studies of the San Andreas fault system throughout its extent within the state of California. Although there is considerable controversy surrounding the question of which segment of the San Andreas system may produce the next earthquake, C.B. Raleigh, K. Sieh, L.R. Sykes, and D.L. Anderson report that it is conceivable that the entire fault in southern California could rupture at once. (Science, Sept. 17, 1982).The fears that a major earthquake may occur at anytime in southern California are based on numerous statistical factors underlying the idea that The longer it's been since the last big one, the sooner the next one will be. The timing of earthquakes along active seismic zones, particularly those that coincide with plate boundaries, seems to be directly related to the amount of displacement generated since the last such earthquake at the same location. For example, the recurrence rate of about 150 years for great earthquakes along the San Andreas fault in southern California and the displacement rate of about 3 cm per year for the segment of the last earthquake from Cholame Valley to Cajon Pass in 1857 suggest that the next such large event may occur in the near future. On this basis Raleigh et al. (Science, sup.) conclude that Both observations mark the San Andreas fault north and east of Los Angeles as a mature seismic gap and the prime candidate for producing southern California's next great earthquake. The expected consequences are described as appalling and as having a potential for severe losses of life and property from such a great earthquake The worst case, cited in a report issued by the National Security Council through the Federal Emergency Management Administration in 1980 for an earthquake magnitude of M=7.5 in southern California near Long Beach, could cause the loss of 20,000 lives and $69 billion in property damages.

  17. Estimating Casualties for Large Earthquakes Worldwide Using an Empirical Approach

    USGS Publications Warehouse

    Jaiswal, Kishor; Wald, David J.; Hearne, Mike

    2009-01-01

    We developed an empirical country- and region-specific earthquake vulnerability model to be used as a candidate for post-earthquake fatality estimation by the U.S. Geological Survey's Prompt Assessment of Global Earthquakes for Response (PAGER) system. The earthquake fatality rate is based on past fatal earthquakes (earthquakes causing one or more deaths) in individual countries where at least four fatal earthquakes occurred during the catalog period (since 1973). Because only a few dozen countries have experienced four or more fatal earthquakes since 1973, we propose a new global regionalization scheme based on idealization of countries that are expected to have similar susceptibility to future earthquake losses given the existing building stock, its vulnerability, and other socioeconomic characteristics. The fatality estimates obtained using an empirical country- or region-specific model will be used along with other selected engineering risk-based loss models for generation of automated earthquake alerts. These alerts could potentially benefit the rapid-earthquake-response agencies and governments for better response to reduce earthquake fatalities. Fatality estimates are also useful to stimulate earthquake preparedness planning and disaster mitigation. The proposed model has several advantages as compared with other candidate methods, and the country- or region-specific fatality rates can be readily updated when new data become available.

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

    USGS Publications Warehouse

    Wheeler, Russell L.

    2014-01-01

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

  19. Major earthquake shakes northern Pakistan

    NASA Astrophysics Data System (ADS)

    Kumar, Mohi

    A magnitude 7.6 earthquake that shook the western Himalayas on 8 October killed at least 23,000 in Pakistan and 1,400 in India, injured more than 50,000 people, and left more 2.5 million people homeless across the Kashmir region. The official death toll could exceed 30,000, placing this among most deadly earthquakes to have ever occurred on the Indian subcontinent.Scientists warn that, given the lack of development and poor construction in the area, future earthquakes in more densely populated areas could be devastating. David Simpson, president of the Incorporated Research Institutes for Seismology, said the 8 October quake ‘was a terrible disaster, but not to the level of what could happen in the future. This is yet again another warning message of things to come.”

  20. Earthquake history of the United States

    USGS Publications Warehouse

    Coffman, Jerry L., (Edited By); Von Hake, Carl A.; Stover, Carl W.

    1982-01-01

    This publication is a history of the prominent earthquakes in the United States from historical times through 1970. It supersedes all previous editions with the same or similar titles (see page ii) and, in addition to updating earthquake listings through 1970, contains several additions and corrections to previous issues. It also brings together under a common cover earthquake data previously listed in two separate reports: Earthquake History of the United States, Part I, Stronger Earthquakes of the United States (Exclusive of California and Western Nevada) and Earthquake History of the United States, Part II, Stronger Earthquakes of California and Western Nevada. Another addition to this publication is the inclusion of a section describing earthquakes in the Puerto Rico region. For the purpose of listing and describing earthquakes, the United States has been divided into nine regions: (1) Northeastern Region, which includes New England and New York activity and observations of the principal earthquakes of eastern Canada; (2) Eastern Region, including the central Appalachian seismic region activity and the area near Charleston, S.C.; (3) Central Region, which consists of the area between the region just described and the Rocky Mountains; (4) Western Mountain Region, which includes all remaining states except those on the Pacific coast; (5) Washington and Oregon; (6) Alaska; (7) Hawaii; (8) Puerto Rico; and (9) California and Western Nevada. This arrangement has been made chiefly with reference to the natural seismic divisions. It also is a convenient arrangement because there are only three states where there is an important division of earthquake activity: In Tennessee, there are quite distinct areas at opposite ends of the state that fall into different regions. Only central and eastern Nevada are included in the Western Mountain Region, as the activity of the western part is closely associated with that of California. Some earthquake activity has occurred in the part of Texas located in the Western Mountain Region. The map facing page 1 shows locations of all earthquakes in the regions that follow. A small map showing the area covered by each region immediately precedes the résumé of each chapter (except for the Alaska, Puerto Rico, and Hawaii regions). The seismic risk map below was developed in January 1969 for the conterminous United States by Dr. S. T. Algermissen of NOAA's Environmental Research Laboratories. Subject to revision as continuing research warrants, it is an updated edition of a map divides the United States into four zones: Zone 0, areas with no reasonable expectancy of earthquake damage; Zone 1, expected minor damage; Zone 2, expected moderate damage; and Zone 3, major destructive earthquakes may occur.

  1. Material contrast does not predict earthquake rupture propagation direction

    USGS Publications Warehouse

    Harris, R.A.; Day, S.M.

    2005-01-01

    Earthquakes often occur on faults that juxtapose different rocks. The result is rupture behavior that differs from that of an earthquake occurring on a fault in a homogeneous material. Previous 2D numerical simulations have studied simple cases of earthquake rupture propagation where there is a material contrast across a fault and have come to two different conclusions: 1) earthquake rupture propagation direction can be predicted from the material contrast, and 2) earthquake rupture propagation direction cannot be predicted from the material contrast. In this paper we provide observational evidence from 70 years of earthquakes at Parkfield, CA, and new 3D numerical simulations. Both the observations and the numerical simulations demonstrate that earthquake rupture propagation direction is unlikely to be predictable on the basis of a material contrast. Copyright 2005 by the American Geophysical Union.

  2. Assessing the risk of earthquakes in the eastern United States

    SciTech Connect

    Not Available

    1981-09-01

    Although earthquakes in the U.S. are generally considered California's problem, a number of major earthquakes have struck the central and eastern United States. The last damaging earthquake in the eastern U.S. occurred in 1886, near Charleston, SC, killing 60 people and causing extensive damage in Charleston. During the winter of 1811-12, three major earthquakes occurred near New Madrid in southeastern Missouri. Because the area, at that time, was sparsely populated, casualties were not extensive, but the quakes caused damage and ground shaking over an area 20 times larger than that for the 1906 San Francisco earthquake. Because of these earthquakes and others, the potential for damaging earthquakes in the eastern U.S. is real, and this was the subject of a recent meeting of geologists, seismologists, and engineers in Knoxville, TN, in September 1981. The highlights of their discussions are presented in this article.

  3. Japanese Encephalitis: Frequently Asked Questions

    MedlinePlus

    ... The disease can progress to inflammation of the brain (encephalitis) and is often accompanied by seizures. Coma and paralysis occur in some cases. Top of Page How is Japanese encephalitis diagnosed? Diagnosis is based on a combination of clinical signs ...

  4. Izmit, Turkey 1999 Earthquake Interferogram

    NASA Technical Reports Server (NTRS)

    2001-01-01

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

  5. Fault failure with moderate earthquakes

    USGS Publications Warehouse

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

    1987-01-01

    High resolution strain and tilt recordings were made in the near-field of, and prior to, the May 1983 Coalinga earthquake (ML = 6.7, ?? = 51 km), the August 4, 1985, Kettleman Hills earthquake (ML = 5.5, ?? = 34 km), the April 1984 Morgan Hill earthquake (ML = 6.1, ?? = 55 km), the November 1984 Round Valley earthquake (ML = 5.8, ?? = 54 km), the January 14, 1978, Izu, Japan earthquake (ML = 7.0, ?? = 28 km), and several other smaller magnitude earthquakes. These recordings were made with near-surface instruments (resolution 10-8), with borehole dilatometers (resolution 10-10) and a 3-component borehole strainmeter (resolution 10-9). While observed coseismic offsets are generally in good agreement with expectations from elastic dislocation theory, and while post-seismic deformation continued, in some cases, with a moment comparable to that of the main shock, preseismic strain or tilt perturbations from hours to seconds (or less) before the main shock are not apparent above the present resolution. Precursory slip for these events, if any occurred, must have had a moment less than a few percent of that of the main event. To the extent that these records reflect general fault behavior, the strong constraint on the size and amount of slip triggering major rupture makes prediction of the onset times and final magnitudes of the rupture zones a difficult task unless the instruments are fortuitously installed near the rupture initiation point. These data are best explained by an inhomogeneous failure model for which various areas of the fault plane have either different stress-slip constitutive laws or spatially varying constitutive parameters. Other work on seismic waveform analysis and synthetic waveforms indicates that the rupturing process is inhomogeneous and controlled by points of higher strength. These models indicate that rupture initiation occurs at smaller regions of higher strength which, when broken, allow runaway catastrophic failure. ?? 1987.

  6. Naturally occurring chemical carcinogens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural products are chemicals found in nature which have unique pharmacological effects. Humans are exposed to many of these bioactive naturally occurring chemicals via the air breathed, the water drunk and the food eaten. Exposure also occurs in clinical settings. Naturally occurring chemicals ...

  7. Pore-fluid migration and the timing of the 2005 M8.7 Nias earthquake

    USGS Publications Warehouse

    Hughes, K.L.H.; Masterlark, Timothy; Mooney, W.D.

    2011-01-01

    Two great earthquakes have occurred recently along the Sunda Trench, the 2004 M9.2 Sumatra-Andaman earthquake and the 2005 M8.7 Nias earthquake. These earthquakes ruptured over 1600 km of adjacent crust within 3 mo of each other. We quantitatively present poroelastic deformation analyses suggesting that postseismic fluid flow and recovery induced by the Sumatra-Andaman earthquake advanced the timing of the Nias earthquake. Simple back-slip simulations indicate that the megapascal (MPa)-scale pore-pressure recovery is equivalent to 7 yr of interseismic Coulomb stress accumulation near the Nias earthquake hypocenter, implying that pore-pressure recovery of the Sumatra-Andaman earthquake advanced the timing of the Nias earthquake by ~7 yr. That is, in the absence of postseismic pore-pressure recovery, we predict that the Nias earthquake would have occurred in 2011 instead of 2005. ?? 2011 Geological Society of America.

  8. Oklahoma's recent earthquakes and saltwater disposal.

    PubMed

    Walsh, F Rall; Zoback, Mark D

    2015-06-01

    Over the past 5 years, parts of Oklahoma have experienced marked increases in the number of small- to moderate-sized earthquakes. In three study areas that encompass the vast majority of the recent seismicity, we show that the increases in seismicity follow 5- to 10-fold increases in the rates of saltwater disposal. Adjacent areas where there has been relatively little saltwater disposal have had comparatively few recent earthquakes. In the areas of seismic activity, the saltwater disposal principally comes from "produced" water, saline pore water that is coproduced with oil and then injected into deeper sedimentary formations. These formations appear to be in hydraulic communication with potentially active faults in crystalline basement, where nearly all the earthquakes are occurring. Although most of the recent earthquakes have posed little danger to the public, the possibility of triggering damaging earthquakes on potentially active basement faults cannot be discounted. PMID:26601200

  9. Parallelization of the Coupled Earthquake Model

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  10. Numerical Simulation of Earthquake Generation Cycles before and after the 2011 Tohoku-Oki Earthquake in Northeast Japan

    NASA Astrophysics Data System (ADS)

    Nakata, R.; Ariyoshi, K.; Hyodo, M.; Hori, T.

    2014-12-01

    Along the Japan Trench, M7 class earthquakes have occurred in the past. Among them, earthquakes off the coast of Miyagi prefecture have occurred with recurrence intervals of approximately 30-40 years. The M 7.2 earthquake in 2005 is the latest before 2011. On 11 March 2011, the M 9.0 great interplate earthquake occurred off the coast of the Tohoku district (including Miyagi). Currently, it has been passed for more than three years since the M 9.0 earthquake. Post-seismic deformation has continued today, and Off-Miyagi earthquake has not occurred yet. We numerically simulated cycles for occurrences of seismic and aseismic events along the Japan Trench with the 3D geometry of the Pacific plate using the aging law, which is a type of rate- and state-dependent friction law. We evaluated simulation results achieved using different values of frictional parameters with respect to characteristics such as the slip history and crustal deformation before the Tohoku-Oki earthquake. Before the Tohoku-Oki earthquake, two slow slip events (SSEs) were observed on 2008 and 2011. The M=7.3 largest foreshock occurred on March 9 [Ito et al., 2013]. Source areas of the mainshock, the foreshock, and the SSEs are in the updip area of the Off-Miyagi earthquakes and post-seismic slip of the M9 earthquake. By now, we have approximately reproduced some characteristics of observed slips by using several sets of frictional parameter values. In our simulations, M=7.0-7.6 foreshock occurred 0.4~7 days before the mainshock (M=8.6-9.0). And the foreshock occurred within 10 years after the M=7.2-7.3 earthquake at Off-Miyagi. In these models, time interval between the mainshock and the first Off-Miyagi earthquake after the great earthquake tend to be shorter than the average recurrence interval of the past. This tendency was observed at Indonesia. Two M7 class earthquakes occurred before (2002) and after (2008) the 2004 Sumatra earthquake (M9.1). The source regions were at the south end of the rupture zone of the 2004 earthquake and the north end of the rupture zone of the 2005 Nias Island earthquake (M8.6) [Shearer & Burgmann, 2010]. We are now improving our model to reproduce other characteristics. Based on some of the reasonable results achieved, we will discuss possible scenarios for spatial-temporal evolution of slip after M9 class earthquakes.

  11. Unusual low-angle normal fault earthquakes after the 2011 Tohoku-oki megathrust earthquake

    NASA Astrophysics Data System (ADS)

    Yagi, Yuji; Okuwaki, Ryo; Enescu, Bogdan; Fukahata, Yukitoshi

    2015-06-01

    A few low-angle normal fault earthquakes at approximately the depth of the plate interface, with a strike nearly parallel to the trench axis, were detected immediately after the 2011 Tohoku-oki earthquake. After that, however, no such normal fault events have been observed until the occurrence of the 2014 M W 6.6 Fukushima-oki earthquake. Here we analyze the teleseismic body waveforms of the 2014 Fukushima-oki earthquake. We first compare the observed teleseismic body waves of the 2014 Fukushima-oki earthquake with those of the largest previous low-angle normal fault aftershock ( M W 6.6), which occurred on 12 March 2011, and then estimate the centroid depth and moment tensor solution of the 2014 Fukushima-oki earthquake. The teleseismic body waves and moment tensor solution of the 2014 Fukushima-oki earthquake are similar to those of the 2011 normal fault aftershock, which suggests that the 2014 Fukushima-oki earthquake occurred at a similar depth and had a similar mechanism to that of the 2011 aftershock. We detected five low-angle normal fault aftershocks at approximately the depth of the plate interface, with a strike nearly parallel to the trench axis, and confirmed that all of them except for the 2014 Fukushima-oki earthquake occurred within 17 days after the mainshock. The occurrence of these low-angle normal fault events is likely to reflect the reversal of shear stress due to overshooting of slip during the 2011 Tohoku-oki earthquake. We speculate that a fast but heterogeneous recovery of stress state at the plate interface may explain why these events preferentially occurred immediately after the megathrust event, while one of them occurred with a significant delay. In order to better understand the characteristics of stress state in the crust, we have to carefully observe the ongoing seismic activity around this region.

  12. Slow earthquakes coincident with episodic tremors and slow slip events.

    PubMed

    Ito, Yoshihiro; Obara, Kazushige; Shiomi, Katsuhiko; Sekine, Shutaro; Hirose, Hitoshi

    2007-01-26

    We report on the very-low-frequency earthquakes occurring in the transition zone of the subducting plate interface along the Nankai subduction zone in southwest Japan. Seismic waves generated by very-low-frequency earthquakes with seismic moment magnitudes of 3.1 to 3.5 predominantly show a long period of about 20 seconds. The seismicity of very-low-frequency earthquakes accompanies and migrates with the activity of deep low-frequency tremors and slow slip events. The coincidence of these three phenomena improves the detection and characterization of slow earthquakes, which are thought to increase the stress on updip megathrust earthquake rupture zones. PMID:17138867

  13. Continuing megathrust earthquake potential in Chile after the 2014 Iquique earthquake

    USGS Publications Warehouse

    Hayes, Gavin P.; Herman, Matthew W.; Barnhart, William D.; Furlong, Kevin P.; Riquelme, Sebástian; Benz, Harley M.; Bergman, Eric; Barrientos, Sergio; Earle, Paul; Samsonov, Sergey

    2014-01-01

    The seismic gap theory identifies regions of elevated hazard based on a lack of recent seismicity in comparison with other portions of a fault. It has successfully explained past earthquakes (see, for example, ref. 2) and is useful for qualitatively describing where large earthquakes might occur. A large earthquake had been expected in the subduction zone adjacent to northern Chile which had not ruptured in a megathrust earthquake since a M ~8.8 event in 1877. On 1 April 2014 a M 8.2 earthquake occurred within this seismic gap. Here we present an assessment of the seismotectonics of the March–April 2014 Iquique sequence, including analyses of earthquake relocations, moment tensors, finite fault models, moment deficit calculations and cumulative Coulomb stress transfer. This ensemble of information allows us to place the sequence within the context of regional seismicity and to identify areas of remaining and/or elevated hazard. Our results constrain the size and spatial extent of rupture, and indicate that this was not the earthquake that had been anticipated. Significant sections of the northern Chile subduction zone have not ruptured in almost 150 years, so it is likely that future megathrust earthquakes will occur to the south and potentially to the north of the 2014 Iquique sequence.

  14. Continuing megathrust earthquake potential in Chile after the 2014 Iquique earthquake

    NASA Astrophysics Data System (ADS)

    Hayes, Gavin P.; Herman, Matthew W.; Barnhart, William D.; Furlong, Kevin P.; Riquelme, Sebstian; Benz, Harley M.; Bergman, Eric; Barrientos, Sergio; Earle, Paul S.; Samsonov, Sergey

    2014-08-01

    The seismic gap theory identifies regions of elevated hazard based on a lack of recent seismicity in comparison with other portions of a fault. It has successfully explained past earthquakes (see, for example, ref. 2) and is useful for qualitatively describing where large earthquakes might occur. A large earthquake had been expected in the subduction zone adjacent to northern Chile, which had not ruptured in a megathrust earthquake since a M ~8.8 event in 1877. On 1 April 2014 a M 8.2 earthquake occurred within this seismic gap. Here we present an assessment of the seismotectonics of the March-April 2014 Iquique sequence, including analyses of earthquake relocations, moment tensors, finite fault models, moment deficit calculations and cumulative Coulomb stress transfer. This ensemble of information allows us to place the sequence within the context of regional seismicity and to identify areas of remaining and/or elevated hazard. Our results constrain the size and spatial extent of rupture, and indicate that this was not the earthquake that had been anticipated. Significant sections of the northern Chile subduction zone have not ruptured in almost 150 years, so it is likely that future megathrust earthquakes will occur to the south and potentially to the north of the 2014 Iquique sequence.

  15. Continuing megathrust earthquake potential in Chile after the 2014 Iquique earthquake.

    PubMed

    Hayes, Gavin P; Herman, Matthew W; Barnhart, William D; Furlong, Kevin P; Riquelme, Sebstian; Benz, Harley M; Bergman, Eric; Barrientos, Sergio; Earle, Paul S; Samsonov, Sergey

    2014-08-21

    The seismic gap theory identifies regions of elevated hazard based on a lack of recent seismicity in comparison with other portions of a fault. It has successfully explained past earthquakes (see, for example, ref.2) and is useful for qualitatively describing where large earthquakes might occur. A large earthquake had been expected in the subduction zone adjacent to northern Chile, which had not ruptured in a megathrust earthquake since a M?8.8 event in 1877. On 1 April 2014 a M8.2 earthquake occurred within this seismic gap. Here we present an assessment of the seismotectonics of the March-April 2014 Iquique sequence, including analyses of earthquake relocations, moment tensors, finite fault models, moment deficit calculations and cumulative Coulomb stress transfer. This ensemble of information allows us to place the sequence within the context of regional seismicity and to identify areas of remaining and/or elevated hazard. Our results constrain the size and spatial extent of rupture, and indicate that this was not the earthquake that had been anticipated. Significant sections of the northern Chile subduction zone have not ruptured in almost 150 years, so it is likely that future megathrust earthquakes will occur to the south and potentially to the north of the 2014 Iquique sequence. PMID:25119028

  16. Recommendations on frequently encountered relief requests

    SciTech Connect

    Hartley, R.S.; Ransom, C.B.

    1992-01-01

    This paper is based on the review of a large database of requests for relief from enservice testing (1ST) requirements for pumps and valves. From the review, the paper identifies areas where enhancements to either the relief request process or the applicable test codes can improve IST of pumps and valves. Certain types of requests occur frequently. The paper examines some frequent requests and considers possible changes to the requirements to determine if the frequent requests can be eliminated. Recommended changes and their bases will be discussed. IST of safety-related pumps and valves at commercial nuclear power plants is done according to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (the Code), Section XI. Because of the design and function of some safety systems in nuclear plants, performing Code testing of certain pumps and valves is impractical or a hardship without a compensating increase in the level of safety. Deviations from the Code are allowed by law, as reviewed and approved by the United States Nuclear Regulatory Commission (NRC), through the relief request process. Because of similarities in plant design and system function, many problems encountered in testing components are similar from plant to plant. Likewise, there are often common problems associated with test methods or equipment. Therefore, many relief requests received by the NRC from various plants are similar. Identifying and addressing the root causes for these common requests will greatly improve IST.

  17. Recommendations on frequently encountered relief requests

    SciTech Connect

    Hartley, R.S.; Ransom, C.B.

    1992-09-01

    This paper is based on the review of a large database of requests for relief from enservice testing (1ST) requirements for pumps and valves. From the review, the paper identifies areas where enhancements to either the relief request process or the applicable test codes can improve IST of pumps and valves. Certain types of requests occur frequently. The paper examines some frequent requests and considers possible changes to the requirements to determine if the frequent requests can be eliminated. Recommended changes and their bases will be discussed. IST of safety-related pumps and valves at commercial nuclear power plants is done according to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (the Code), Section XI. Because of the design and function of some safety systems in nuclear plants, performing Code testing of certain pumps and valves is impractical or a hardship without a compensating increase in the level of safety. Deviations from the Code are allowed by law, as reviewed and approved by the United States Nuclear Regulatory Commission (NRC), through the relief request process. Because of similarities in plant design and system function, many problems encountered in testing components are similar from plant to plant. Likewise, there are often common problems associated with test methods or equipment. Therefore, many relief requests received by the NRC from various plants are similar. Identifying and addressing the root causes for these common requests will greatly improve IST.

  18. Issues on the Japanese Earthquake Hazard Evaluation

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    The 2011 Great East Japan Earthquake forced the policy of counter-measurements to earthquake disasters, including earthquake hazard evaluations, to be changed in Japan. Before the March 11, Japanese earthquake hazard evaluation was based on the history of earthquakes that repeatedly occurs and the characteristic earthquake model. The source region of an earthquake was identified and its occurrence history was revealed. Then the conditional probability was estimated using the renewal model. However, the Japanese authorities changed the policy after the megathrust earthquake in 2011 such that the largest earthquake in a specific seismic zone should be assumed on the basis of available scientific knowledge. According to this policy, three important reports were issued during these two years. First, the Central Disaster Management Council issued a new estimate of damages by a hypothetical Mw9 earthquake along the Nankai trough during 2011 and 2012. The model predicts a 34 m high tsunami on the southern Shikoku coast and intensity 6 or higher on the JMA scale in most area of Southwest Japan as the maximum. Next, the Earthquake Research Council revised the long-term earthquake hazard evaluation of earthquakes along the Nankai trough in May 2013, which discarded the characteristic earthquake model and put much emphasis on the diversity of earthquakes. The so-called 'Tokai' earthquake was negated in this evaluation. Finally, another report by the CDMC concluded that, with the current knowledge, it is hard to predict the occurrence of large earthquakes along the Nankai trough using the present techniques, based on the diversity of earthquake phenomena. These reports created sensations throughout the country and local governments are struggling to prepare counter-measurements. These reports commented on large uncertainty in their evaluation near their ends, but are these messages transmitted properly to the public? Earthquake scientists, including authors, are involved in the discussion of these issues as committee members. However, we are wondering if the basis of these reports is scientifically appropriate. For example, there is no established method to evaluate the maximum size of earthquake, whose record is not known, in a specific area, but the committee made an estimate for the Nankai trough by extrapolating available knowledge. The Japanese policy makers further requested the probability of occurrence of such an event, which the committee had to decline because of the lack of knowledge. This example shows that Japanese earthquake scientists sometimes are involved in an important decision-making and are urged to go beyond the limit of earthquake science. We consider this difficult situation is formed on the basis of the history of the Japanese earthquake science and the 'myth of flawless of science' in the government and society, who often ask for a simple answer. Open discussion with people from other fields of science, such as social and human sciences, and the public would be an effective solution for the public to understand the complexity of the problems and to encourage appropriate counter-measures.

  19. Megathrust earthquakes in Central Chile: What is next after the Maule 2010 earthquake?

    NASA Astrophysics Data System (ADS)

    Madariaga, R.

    2013-05-01

    The 27 February 2010 Maule earthquake occurred in a well identified gap in the Chilean subduction zone. The event has now been studied in detail using both far-field, near field seismic and geodetic data, we will review this information gathered so far. The event broke a region that was much longer along strike than the gap left over from the 1835 Concepcion earthquake, sometimes called the Darwin earthquake because he was in the area when the earthquake occurred and made many observations. Recent studies of contemporary documents by Udias et al indicate that the area broken by the Maule earthquake in 2010 had previously broken by a similar earthquake in 1751, but several events in the magnitude 8 range occurred in the area principally in 1835 already mentioned and, more recently on 1 December 1928 to the North and on 21 May 1960 (1 1/2 days before the big Chilean earthquake of 1960). Currently the area of the 2010 earthquake and the region immediately to the North is undergoing a very large increase in seismicity with numerous clusters of seismicity that move along the plate interface. Examination of the seismicity of Chile of the 18th and 19th century show that the region immediately to the North of the 2010 earthquake broke in a very large megathrust event in July 1730. this is the largest known earthquake in central Chile. The region where this event occurred has broken in many occasions with M 8 range earthquakes in 1822, 1880, 1906, 1971 and 1985. Is it preparing for a new very large megathrust event? The 1906 earthquake of Mw 8.3 filled the central part of the gap but it has broken again on several occasions in 1971, 1973 and 1985. The main question is whether the 1906 earthquake relieved enough stresses from the 1730 rupture zone. Geodetic data shows that most of the region that broke in 1730 is currently almost fully locked from the northern end of the Maule earthquake at 34.5°S to 30°S, near the southern end of the of the Mw 8.5 Atacama earthquake of 11 November 1922. This regions needs special surveillance.

  20. [Evidence-based medicine: a discussion of the most frequently occurring criticisms].

    PubMed

    Hannes, K; Aertgeerts, B; Schepers, R; Goedhuys, J; Buntinx, F

    2005-09-01

    Since the introduction of evidence-based medicine (EBM) into the field of health care in the early nineties some major criticisms have appeared in scientific literature. One of the most commonly heard objections to EBM is loss of therapeutic freedom. However even with the advent of EBM the physician continues to look for solutions that are tailored to the patient. The available evidence is often inadequate, there are many inconsistencies and contradictions in the research material and the published outcomes are distorted by publication bias. There is resistance to the opinion that randomized clinical trials (RCTs) provide the best foundations on which to build clinical policies. There must always be room for views expressed in other types of study. EBM is primarily for academics and does not take clinical expertise into account. However as the results of scientific research are becoming increasingly available to a wider public, patients are able to challenge the decisions made by their health-care practitioners and push them to provide the motivation for their decisions. Many health-care practitioners have commented that they always have to take the results of scientific research into account. One strength of EBM in this is the transparent manner in which the overview of the literature develops and the systematic approach to results from scientific study. After all, there is insufficient evidence that the EBM process works effectively and that it therefore improves patient care. It is true to say that patients who receive treatment of which the efficacy has been proven experience better treatment results than other patients. Setting up a definitive randomized study to answer this question would be difficult if not impossible. EBM is an aid to support clinical decision making. The development of principles on which to base this way of thinking and acting and the quest for suitable research designs and the most objective research results in order to be able to answer all the questions posed by caregivers, is not yet complete. EBM is just one of the weapons in the armoury of the caregiver in the battle for the optimal provision. PMID:16171109

  1. THE PERIOD OF LIFE AT WHICH INFECTION FROM TUBERCULOSIS OCCURS MOST FREQUENTLY

    PubMed Central

    Knopf, S. Adolphus

    1916-01-01

    This paper not only contains Doctor Knopf's own valuable conclusions upon the subject presented, but it is also a compendium of the opinions which Doctor Knopf has secured from a number of other eminent physicians. PMID:18009535

  2. Frog Swarms: Earthquake Precursors or False Alarms?

    PubMed Central

    Grant, Rachel A.; Conlan, Hilary

    2013-01-01

    Simple Summary Media reports linking unusual animal behaviour with earthquakes can potentially create false alarms and unnecessary anxiety among people that live in earthquake risk zones. Recently large frog swarms in China and elsewhere have been reported as earthquake precursors in the media. By examining international media reports of frog swarms since 1850 in comparison to earthquake data, it was concluded that frog swarms are naturally occurring dispersal behaviour of juveniles and are not associated with earthquakes. However, the media in seismic risk areas may be more likely to report frog swarms, and more likely to disseminate reports on frog swarms after earthquakes have occurred, leading to an apparent link between frog swarms and earthquakes. Abstract In short-term earthquake risk forecasting, the avoidance of false alarms is of utmost importance to preclude the possibility of unnecessary panic among populations in seismic hazard areas. Unusual animal behaviour prior to earthquakes has been reported for millennia but has rarely been scientifically documented. Recently large migrations or unusual behaviour of amphibians have been linked to large earthquakes, and media reports of large frog and toad migrations in areas of high seismic risk such as Greece and China have led to fears of a subsequent large earthquake. However, at certain times of year large migrations are part of the normal behavioural repertoire of amphibians. News reports of “frog swarms” from 1850 to the present day were examined for evidence that this behaviour is a precursor to large earthquakes. It was found that only two of 28 reported frog swarms preceded large earthquakes (Sichuan province, China in 2008 and 2010). All of the reported mass migrations of amphibians occurred in late spring, summer and autumn and appeared to relate to small juvenile anurans (frogs and toads). It was concluded that most reported “frog swarms” are actually normal behaviour, probably caused by juvenile animals migrating away from their breeding pond, after a fruitful reproductive season. As amphibian populations undergo large fluctuations in numbers from year to year, this phenomenon will not occur on a yearly basis but will depend on successful reproduction, which is related to numerous climatic and geophysical factors. Hence, most large swarms of amphibians, particularly those involving very small frogs and occurring in late spring or summer, are not unusual and should not be considered earthquake precursors. In addition, it is likely that reports of several mass migration of small toads prior to the Great Sichuan Earthquake in 2008 were not linked to the subsequent M = 7.9 event (some occurred at a great distance from the epicentre), and were probably co-incidence. Statistical analysis of the data indicated frog swarms are unlikely to be connected with earthquakes. Reports of unusual behaviour giving rise to earthquake fears should be interpreted with caution, and consultation with experts in the field of earthquake biology is advised. PMID:26479746

  3. Surface displacements in the 1906 san francisco and 1989 loma prieta earthquakes.

    PubMed

    Segall, P; Lisowski, M

    1990-11-30

    The horizontal displacements accompanying the 1906 San Francisco earthquake and the 1989 Loma Prieta earthquake are computed from geodetic survey measurements. The 1906 earthquake displacement field is entirely consistent with right-lateral strike slip on the San Andreas fault. In contrast, the 1989 Loma Prieta earthquake exhibited subequal components of strike slip and reverse faulting. This result, together with other seismic and geologic data, may indicate that the two earthquakes occurred on two different fault planes. PMID:17829210

  4. Surface displacements in the 1906 San Francisco and 1989 Loma Prieta Earthquakes

    SciTech Connect

    Segall, P. Geological Survey, Menlo Park, CA ); Lisowski, M. )

    1990-11-30

    The horizontal displacements accompanying the 1906 San Francisco earthquake and the 1989 Loma Prieta earthquake are computed from geodetic survey measurements. The 1906 earthquake displacement field is entirely consistent with right-lateral strike slip on the San Andreas fault. In contrast, the 1989 Loma Prieta earthquake exhibited subequal components of strike slip and reverse faulting. This result, together with other seismic and geologic data, may indicate that the two earthquakes occurred on two different fault planes.

  5. Surface displacements in the 1906 San Francisco and 1989 Loma Prieta earthquakes

    USGS Publications Warehouse

    Segall, P.; Lisowski, M.

    1990-01-01

    The horizontal displacements accompanying the 1906 San Francisco earthquake and the 1989 Loma Prieta earthquake are computed from geodetic survey measurements. The 1906 earthquake displacement field is entirely consistent with right-lateral strike slip on the San Andreas fault. In contrast, the 1989 Loma Prieta earthquake exhibited subequal components of strike slip and reverse faulting. This result, together with other seismic and geologic data, may indicate that the two earthquakes occurred on two different fault planes.

  6. Napa Earthquake impact on water systems

    NASA Astrophysics Data System (ADS)

    Wang, J.

    2014-12-01

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

  7. Loss estimation of Membramo earthquake

    NASA Astrophysics Data System (ADS)

    Damanik, R.; Sedayo, H.

    2016-05-01

    Papua Tectonics are dominated by the oblique collision of the Pacific plate along the north side of the island. A very high relative plate motions (i.e. 120 mm/year) between the Pacific and Papua-Australian Plates, gives this region a very high earthquake production rate, about twice as much as that of Sumatra, the western margin of Indonesia. Most of the seismicity occurring beneath the island of New Guinea is clustered near the Huon Peninsula, the Mamberamo region, and the Bird's Neck. At 04:41 local time(GMT+9), July 28th 2015, a large earthquake of Mw = 7.0 occurred at West Mamberamo Fault System. The earthquake focal mechanism are dominated by northwest-trending thrust mechanisms. GMPE and ATC vulnerability curve were used to estimate distribution of damage. Mean of estimated losses was caused by this earthquake is IDR78.6 billion. We estimated insurance loss will be only small portion in total general due to deductible.

  8. Catalog of significant historical earthquakes in the Central United States

    USGS Publications Warehouse

    Bakun, W.H.; Hopper, M.G.

    2004-01-01

    We use Modified Mercalli intensity assignments to estimate source locations and moment magnitude M for eighteen 19th-century and twenty early- 20th-century earthquakes in the central United States (CUS) for which estimates of M are otherwise not available. We use these estimates, and locations and M estimated elsewhere, to compile a catelog of significant historical earthquakes in the CUS. The 1811-1812 New Madrid earthquakes apparently dominated CUS seismicity in the first two decades of the 19th century. M5-6 earthquakes occurred in the New Madrid Seismic Zone in 1843 and 1878, but none have occurred since 1878. There has been persistent seismic activity in the Illinois Basin in southern Illinois and Indiana, with M > 5.0 earthquakes in 1895, 1909, 1917, 1968, and 1987. Four other M > 5.0 CUS historical earthquakes have occurred: in Kansas in 1867, in Nebraska in 1877, in Oklahoma in 1882, and in Kentucky in 1980.

  9. Earthquakes - Volcanoes (Causes - Forecast - Counteraction)

    NASA Astrophysics Data System (ADS)

    Tsiapas, Elias

    2013-04-01

    Earthquakes and volcanoes are caused by: 1)Various liquid elements (e.g. H20, H2S, S02) which emerge from the pyrosphere and are trapped in the space between the solid crust and the pyrosphere (Moho discontinuity). 2)Protrusions of the solid crust at the Moho discontinuity (mountain range roots, sinking of the lithosphere's plates). 3)The differential movement of crust and pyrosphere. The crust misses one full rotation for approximately every 100 pyrosphere rotations, mostly because of the lunar pull. The above mentioned elements can be found in small quantities all over the Moho discontinuity, and they are constantly causing minor earthquakes and small volcanic eruptions. When large quantities of these elements (H20, H2S, SO2, etc) concentrate, they are carried away by the pyrosphere, moving from west to east under the crust. When this movement takes place under flat surfaces of the solid crust, it does not cause earthquakes. But when these elements come along a protrusion (a mountain root) they concentrate on its western side, displacing the pyrosphere until they fill the space created. Due to the differential movement of pyrosphere and solid crust, a vacuum is created on the eastern side of these protrusions and when the aforementioned liquids overfill this space, they explode, escaping to the east. At the point of their escape, these liquids are vaporized and compressed, their flow accelerates, their temperature rises due to fluid friction and they are ionized. On the Earth's surface, a powerful rumbling sound and electrical discharges in the atmosphere, caused by the movement of the gasses, are noticeable. When these elements escape, the space on the west side of the protrusion is violently taken up by the pyrosphere, which collides with the protrusion, causing a major earthquake, attenuation of the protrusions, cracks on the solid crust and damages to structures on the Earth's surface. It is easy to foresee when an earthquake will occur and how big it is going to be, when we know the record of specific earthquakes and the routes they have followed towards the East. For example, to foresee an earthquake in the Mediterranean region, we take starting point earthquakes to Latin America (0°-40°).The aforementioned elements will reach Italy in an average time period of 49 days and Greece in 53 days. The most reliable preceding phenomenon to determine the epicenter of an earthquake is the rise of the crust's temperature at the area where a large quantity of elements is concentrated, among other phenomena that can be detected either by instruments or by our senses. When there is an active volcano along the route between the area where the "starting-point" earthquake occurred and the area where we expect the same elements to cause a new earthquake, it is possible these elements will escape through the volcano's crater, carrying lava with them. We could contribute to that end, nullifying earthquakes that might be triggered by these elements further to the east, by using manmade resources, like adequate quantities of explosives at the right moment.

  10. EARTHQUAKES - VOLCANOES (Causes - Forecast - Counteraction)

    NASA Astrophysics Data System (ADS)

    Tsiapas, Elias

    2014-05-01

    Earthquakes and volcanoes are caused by: 1)Various liquid elements (e.g. H20, H2S, S02) which emerge from the pyrosphere and are trapped in the space between the solid crust and the pyrosphere (Moho discontinuity). 2)Protrusions of the solid crust at the Moho discontinuity (mountain range roots, sinking of the lithosphere's plates). 3)The differential movement of crust and pyrosphere. The crust misses one full rotation for approximately every 100 pyrosphere rotations, mostly because of the lunar pull. The above mentioned elements can be found in small quantities all over the Moho discontinuity, and they are constantly causing minor earthquakes and small volcanic eruptions. When large quantities of these elements (H20, H2S, SO2, etc) concentrate, they are carried away by the pyrosphere, moving from west to east under the crust. When this movement takes place under flat surfaces of the solid crust, it does not cause earthquakes. But when these elements come along a protrusion (a mountain root) they concentrate on its western side, displacing the pyrosphere until they fill the space created. Due to the differential movement of pyrosphere and solid crust, a vacuum is created on the eastern side of these protrusions and when the aforementioned liquids overfill this space, they explode, escaping to the east. At the point of their escape, these liquids are vaporized and compressed, their flow accelerates, their temperature rises due to fluid friction and they are ionized. On the Earth's surface, a powerful rumbling sound and electrical discharges in the atmosphere, caused by the movement of the gasses, are noticeable. When these elements escape, the space on the west side of the protrusion is violently taken up by the pyrosphere, which collides with the protrusion, causing a major earthquake, attenuation of the protrusions, cracks on the solid crust and damages to structures on the Earth's surface. It is easy to foresee when an earthquake will occur and how big it is going to be, when we know the record of specific earthquakes and the routes they have followed towards the East. For example, to foresee an earthquake in the Mediterranean region, we take starting point earthquakes to Latin America (0°-40°).The aforementioned elements will reach Italy in an average time period of 49 days and Greece in 53 days. The most reliable preceding phenomenon to determine the epicenter of an earthquake is the rise of the crust's temperature at the area where a large quantity of elements is concentrated, among other phenomena that can be detected either by instruments or by our senses. When there is an active volcano along the route between the area where the "starting-point" earthquake occurred and the area where we expect the same elements to cause a new earthquake, it is possible these elements will escape through the volcano's crater, carrying lava with them. We could contribute to that end, nullifying earthquakes that might be triggered by these elements further to the east, by using manmade resources, like adequate quantities of explosives at the right moment.

  11. Earthquakes - Volcanoes (Causes - Forecast - Counteraction)

    NASA Astrophysics Data System (ADS)

    Tsiapas, Elias

    2015-04-01

    Earthquakes and volcanoes are caused by: 1) Various liquid elements (e.g. H20, H2S, S02) which emerge from the pyrosphere and are trapped in the space between the solid crust and the pyrosphere (Moho discontinuity). 2) Protrusions of the solid crust at the Moho discontinuity (mountain range roots, sinking of the lithosphere's plates). 3) The differential movement of crust and pyrosphere. The crust misses one full rotation for approximately every 100 pyrosphere rotations, mostly because of the lunar pull. The above mentioned elements can be found in small quantities all over the Moho discontinuity, and they are constantly causing minor earthquakes and small volcanic eruptions. When large quantities of these elements (H20, H2S, SO2, etc) concentrate, they are carried away by the pyrosphere, moving from west to east under the crust. When this movement takes place under flat surfaces of the solid crust, it does not cause earthquakes. But when these elements come along a protrusion (a mountain root) they concentrate on its western side, displacing the pyrosphere until they fill the space created. Due to the differential movement of pyrosphere and solid crust, a vacuum is created on the eastern side of these protrusions and when the aforementioned liquids overfill this space, they explode, escaping to the east. At the point of their escape, these liquids are vaporized and compressed, their flow accelerates, their temperature rises due to fluid friction and they are ionized. On the Earth's surface, a powerful rumbling sound and electrical discharges in the atmosphere, caused by the movement of the gasses, are noticeable. When these elements escape, the space on the west side of the protrusion is violently taken up by the pyrosphere, which collides with the protrusion, causing a major earthquake, attenuation of the protrusions, cracks on the solid crust and damages to structures on the Earth's surface. It is easy to foresee when an earthquake will occur and how big it is going to be, when we know the record of specific earthquakes and the routes they have followed towards the East. For example, to foresee an earthquake in the Mediterranean region, we take starting point earthquakes to Latin America (0°-40°).The aforementioned elements will reach Italy in an average time period of 49 days and Greece in 53 days. The most reliable preceding phenomenon to determine the epicenter of an earthquake is the rise of the crust's temperature at the area where a large quantity of elements is concentrated, among other phenomena that can be detected either by instruments or by our senses. When there is an active volcano along the route between the area where the "starting-point" earthquake occurred and the area where we expect the same elements to cause a new earthquake, it is possible these elements will escape through the volcano's crater, carrying lava with them. We could contribute to that end, nullifying earthquakes that might be triggered by these elements further to the east, by using manmade resources, like adequate quantities of explosives at the right moment.

  12. Multiple asperity model for earthquake prediction

    USGS Publications Warehouse

    Wyss, M.; Johnston, A.C.; Klein, F.W.

    1981-01-01

    Large earthquakes often occur as multiple ruptures reflecting strong variations of stress level along faults. Dense instrument networks with which the volcano Kilauea is monitored provided detailed data on changes of seismic velocity, strain accumulation and earthquake occurrence rate before the 1975 Hawaii 7.2-mag earthquake. During the ???4 yr of preparation time the mainshock source volume had separated into crustal volumes of high stress levels embedded in a larger low-stress volume, showing respectively high- and low-stress precursory anomalies. ?? 1981 Nature Publishing Group.

  13. Randomness of megathrust earthquakes implied by rapid stress recovery after the Japan earthquake

    NASA Astrophysics Data System (ADS)

    Tormann, Thessa; Enescu, Bogdan; Woessner, Jochen; Wiemer, Stefan

    2015-02-01

    Constraints on the recurrence times of subduction zone earthquakes are important for seismic hazard assessment and mitigation. Models of such megathrust earthquakes often assume that subduction zones are segmented and earthquakes occur quasi-periodically owing to constant tectonic loading. Here we analyse the occurrence of small earthquakes compared to larger ones--the b-values--on a 1,000-km-long section of the subducting Pacific Plate beneath central and northern Japan since 1998. We find that the b-values vary spatially and mirror the tectonic regime. For example, high b-values, indicative of low stress, occur in locations characterized by deep magma chambers and low b-values, or high stress, occur where the subducting and overriding plates are strongly coupled. There is no significant variation in the low b-values to suggest the plate interface is segmented in a way that might limit potential ruptures. Parts of the plate interface that ruptured during the 2011 Tohoku-oki earthquake were highly stressed in the years leading up to the earthquake. Although the stress was largely released during the 2011 rupture, we find that the stress levels quickly recovered to pre-quake levels within just a few years. We conclude that large earthquakes may not have a characteristic location, size or recurrence interval, and might therefore occur more randomly distributed in time.

  14. Earthquake rate and magnitude distributions of great earthquakes for use in global forecasts

    NASA Astrophysics Data System (ADS)

    Kagan, Yan Y.; Jackson, David D.

    2016-04-01

    We have obtained new results in the statistical analysis of global earthquake catalogs with special attention to the largest earthquakes, and we examined the statistical behavior of earthquake rate variations. These results can serve as an input for updating our recent earthquake forecast, known as the "Global Earthquake Activity Rate 1" model (GEAR1), which is based on past earthquakes and geodetic strain rates. The GEAR1 forecast is expressed as the rate density of all earthquakes above magnitude 5.8 within 70 km of sea level everywhere on earth at 0.1 by 0.1 degree resolution, and it is currently being tested by the Collaboratory for Study of Earthquake Predictability. The seismic component of the present model is based on a smoothed version of the Global Centroid Moment Tensor (GCMT) catalog from 1977 through 2013. The tectonic component is based on the Global Strain Rate Map, a "General Earthquake Model" (GEM) product. The forecast was optimized to fit the GCMT data from 2005 through 2012, but it also fit well the earthquake locations from 1918 to 1976 reported in the International Seismological Centre-Global Earthquake Model (ISC-GEM) global catalog of instrumental and pre-instrumental magnitude determinations. We have improved the recent forecast by optimizing the treatment of larger magnitudes and including a longer duration (1918-2011) ISC-GEM catalog of large earthquakes to estimate smoothed seismicity. We revised our estimates of upper magnitude limits, described as corner magnitudes, based on the massive earthquakes since 2004 and the seismic moment conservation principle. The new corner magnitude estimates are somewhat larger than but consistent with our previous estimates. For major subduction zones we find the best estimates of corner magnitude to be in the range 8.9 to 9.6 and consistent with a uniform average of 9.35. Statistical estimates tend to grow with time as larger earthquakes occur. However, by using the moment conservation principle that equates the seismic moment rate with the tectonic moment rate inferred from geodesy and geology, we obtain a consistent estimate of the corner moment largely independent of seismic history. These evaluations confirm the above-mentioned corner magnitude value. The new estimates of corner magnitudes are important both for the forecast part based on seismicity as well as the part based on geodetic strain rates. We examine rate variations as expressed by annual earthquake numbers. Earthquakes larger than magnitude 6.5 obey the Poisson distribution. For smaller events the negative-binomial distribution fits much better because it allows for earthquake clustering.

  15. Research on earthquake prediction from infrared cloud images

    NASA Astrophysics Data System (ADS)

    Fan, Jing; Chen, Zhong; Yan, Liang; Gong, Jing; Wang, Dong

    2015-12-01

    In recent years, the occurrence of large earthquakes is frequent all over the word. In the face of the inevitable natural disasters, the prediction of the earthquake is particularly important to avoid more loss of life and property. Many achievements in the field of predict earthquake from remote sensing images have been obtained in the last few decades. But the traditional prediction methods presented do have the limitations of can't forecast epicenter location accurately and automatically. In order to solve the problem, a new predicting earthquakes method based on extract the texture and emergence frequency of the earthquake cloud is proposed in this paper. First, strengthen the infrared cloud images. Second, extract the texture feature vector of each pixel. Then, classified those pixels and converted to several small suspected area. Finally, tracking the suspected area and estimate the possible location. The inversion experiment of Ludian earthquake show that this approach can forecast the seismic center feasible and accurately.

  16. A Statistical Analysis of Lunisolar-Earthquake Connections

    NASA Astrophysics Data System (ADS)

    Rüegg, Christian Michael-André

    2012-11-01

    Despite over a century of study, the relationship between lunar cycles and earthquakes remains controversial and difficult to quantitatively investigate. Perhaps as a consequence, major earthquakes around the globe are frequently followed by "prediction claim", using lunar cycles, that generate media furore and pressure scientists to provide resolute answers. The 2010-2011 Canterbury earthquakes in New Zealand were no exception; significant media attention was given to lunar derived earthquake predictions by non-scientists, even though the predictions were merely "opinions" and were not based on any statistically robust temporal or causal relationships. This thesis provides a framework for studying lunisolar earthquake temporal relationships by developing replicable statistical methodology based on peer reviewed literature. Notable in the methodology is a high accuracy ephemeris, called ECLPSE, designed specifically by the author for use on earthquake catalogs and a model for performing phase angle analysis.

  17. In search of earthquake-related hydrologic and chemical changes along Hayward Fault

    USGS Publications Warehouse

    King, C.-Y.; Basler, D.; Presser, T.S.; Evans, William C.; White, L.D.; Minissale, A.

    1994-01-01

    Flow and chemical measurements have been made about once a month, and more frequently when required, since 1976 at two springs in Alum Rock Park in eastern San Jose, California, and since 1980 at two shallow wells in eastern Oakland in search of earthquake-related changes. All sites are on or near the Hayward Fault and are about 55 km apart. Temperature, electric conductivity, and water level or flow rate were measured in situ with portable instruments. Water samples were collected for later chemical and isotopic analyses in the laboratory. The measured flow rate at one of the springs showed a long-term decrease of about 40% since 1987, when a multi-year drought began in California. It also showed several increases that lasted a few days to a few months with amplitudes of 2.4 to 8.6 times the standard deviations above the background rate. Five of these increases were recorded shortly after nearby earthquakes of magnitude 5.0 or larger, and may have resulted from unclogging of the flow path and increase of permeability caused by strong seismic shaking. Two other flow increases were possibly induced by exceptionally heavy rainfalls. The water in both wells showed seasonal temperature and chemical variations, largely in response to rainfall. In 1980 the water also showed some clear chemical changes unrelated to rainfall that lasted a few months; these changes were followed by a magnitude 4 earthquake 37 km away. The chemical composition at one of the wells and at the springs also showed some longer-term variations that were not correlated with rainfall but possibly correlated with the five earthquakes mentioned above. These correlations suggest a common tectonic origin for the earthquakes and the anomalies. The last variation at the affected well occurred abruptly in 1989, shortly before a magnitude 5.0 earthquake 54 km away. ?? 1993.

  18. The Cascadia Subduction Zone and related subduction systems: seismic structure, intraslab earthquakes and processes, and earthquake hazards

    USGS Publications Warehouse

    Kirby, Stephen H.; Wang, Kelin; Dunlop, Susan

    2002-01-01

    The following report is the principal product of an international workshop titled “Intraslab Earthquakes in the Cascadia Subduction System: Science and Hazards” and was sponsored by the U.S. Geological Survey, the Geological Survey of Canada and the University of Victoria. This meeting was held at the University of Victoria’s Dunsmuir Lodge, Vancouver Island, British Columbia, Canada on September 18–21, 2000 and brought 46 participants from the U.S., Canada, Latin America and Japan. This gathering was organized to bring together active research investigators in the science of subduction and intraslab earthquake hazards. Special emphasis was given to “warm-slab” subduction systems, i.e., those systems involving young oceanic lithosphere subducting at moderate to slow rates, such as the Cascadia system in the U.S. and Canada, and the Nankai system in Japan. All the speakers and poster presenters provided abstracts of their presentations that were a made available in an abstract volume at the workshop. Most of the authors subsequently provided full articles or extended abstracts for this volume on the topics that they discussed at the workshop. Where updated versions were not provided, the original workshop abstracts have been included. By organizing this workshop and assembling this volume, our aim is to provide a global perspective on the science of warm-slab subduction, to thereby advance our understanding of internal slab processes and to use this understanding to improve appraisals of the hazards associated with large intraslab earthquakes in the Cascadia system. These events have been the most frequent and damaging earthquakes in western Washington State over the last century. As if to underscore this fact, just six months after this workshop was held, the magnitude 6.8 Nisqually earthquake occurred on February 28th, 2001 at a depth of about 55 km in the Juan de Fuca slab beneath the southern Puget Sound region of western Washington. The Governor’s Office of the State of Washington estimated damage at more than US$2 billion, making it among the costliest earthquakes in U.S. history.

  19. Earthquake swarms in South America

    NASA Astrophysics Data System (ADS)

    Holtkamp, S. G.; Pritchard, M. E.; Lohman, R. B.

    2011-10-01

    We searched for earthquake swarms in South America between 1973 and 2009 using the global Preliminary Determination of Epicenters (PDE) catalogue. Seismicity rates vary greatly over the South American continent, so we employ a manual search approach that aims to be insensitive to spatial and temporal scales or to the number of earthquakes in a potential swarm. We identify 29 possible swarms involving 5-180 earthquakes each (with total swarm moment magnitudes between 4.7 and 6.9) within a range of tectonic and volcanic locations. Some of the earthquake swarms on the subduction megathrust occur as foreshocks and delineate the limits of main shock rupture propagation for large earthquakes, including the 2010 Mw 8.8 Maule, Chile and 2007 Mw 8.1 Pisco, Peru earthquakes. Also, subduction megathrust swarms commonly occur at the location of subduction of aseismic ridges, including areas of long-standing seismic gaps in Peru and Ecuador. The magnitude-frequency relationship of swarms we observe appears to agree with previously determined magnitude-frequency scaling for swarms in Japan. We examine geodetic data covering five of the swarms to search for an aseismic component. Only two of these swarms (at Copiapó, Chile, in 2006 and near Ticsani Volcano, Peru, in 2005) have suitable satellite-based Interferometric Synthetic Aperture Radar (InSAR) observations. We invert the InSAR geodetic signal and find that the ground deformation associated with these swarms does not require a significant component of aseismic fault slip or magmatic intrusion. Three swarms in the vicinity of the volcanic arc in southern Peru appear to be triggered by the Mw= 8.5 2001 Peru earthquake, but predicted static Coulomb stress changes due to the main shock were very small at the swarm locations, suggesting that dynamic triggering processes may have had a role in their occurrence. Although we identified few swarms in volcanic regions, we suggest that particularly large volcanic swarms (those that could be detected using the PDE catalogue) occur in areas of infrequent eruption and may be related to large regional fault zones.

  20. The Nankai Trough earthquake tsunamis in Korea: numerical studies of the 1707 Hoei earthquake and physics-based scenarios

    NASA Astrophysics Data System (ADS)

    Kim, SatByul; Saito, Tatsuhiko; Fukuyama, Eiichi; Kang, Tae-Seob

    2016-04-01

    Historical documents in Korea and China report abnormal waves in the sea and rivers close to the date of the 1707 Hoei earthquake, which occurred in the Nankai Trough, off southwestern Japan. This indicates that the tsunami caused by the Hoei earthquake might have reached Korea and China, which suggests a potential hazard in Korea from large earthquakes in the Nankai Trough. We conducted tsunami simulations to study the details of tsunamis in Korea caused by large earthquakes. Our results showed that the Hoei earthquake (Mw 8.8) tsunami reached the Korean Peninsula about 200 min after the earthquake occurred. The maximum tsunami height was ~0.5 m along the Korean coast. The model of the Hoei earthquake predicted a long-lasting tsunami whose highest peak arrived 600 min later after the first arrival near the coastline of Jeju Island. In addition, we conducted tsunami simulations using physics-based scenarios of anticipated earthquakes in the Nankai subduction zone. The maximum tsunami height in the scenarios (Mw 8.5-8.6) was ~0.4 m along the Korean coast. As a simple evaluation of larger possible tsunamis, we increased the amount of stress released by the earthquake by a factor of two and three, resulting in scenarios for Mw 8.8 and 8.9 earthquakes, respectively. The tsunami height increased by 0.1-0.4 m compared to that estimated by the Hoei earthquake.

  1. Evidence of cumulative offset along the inland Itozawa fault possibly triggered by the past M9 Tohoku, Japan, megathrust earthquakes revealed from a borehole survey

    NASA Astrophysics Data System (ADS)

    Niwa, Y.; Toda, S.; Omata, M.; Mori, Y.

    2013-12-01

    The gigantic Mw 9.0 11 March 2011 Tohoku earthquake suddenly changed the overriding inland area from a compressional stress to an extensional stress regime and then triggered massive seismic swarms in the coastal Fukushima region. The Fukushima-ken-hamadori earthquake on 11 April 2011 (hereinafter, Iwaki earthquake), which was the largest inland off-fault aftershock of the Tohoku earthquake, ruptured the two previously mapped normal faults, the Yunodake fault and the Itozawa fault (Toda and Tsutsumi, BSSA, 2013). The Iwaki earthquake implies that the past gigantic megathrust earthquakes, if they exist, might have frequently triggered slip on similar normal faults including the Itozawa and Yunodake faults themselves. Ideally, collecting all the paleoseismic records from all the normal faults would give us the history of the past M9 class megathrust events and an average inter-event time. Among the series of surveys including paleoseismic trenches (e.g., Toda and Tsutsumi, 2013), we conducted a borehole survey across the central part of the Itozawa fault (Shionohira, Iwaki City), where the maximum vertical displacement 2.1 m was measured. In both upthrown and downthrown sides, extracted core samples expose bedrock conglomerate, fluvial sand and gravel deposits, and artificial fill, from lower to upper, in ascending order. Only in downthrown side, an organic-rich fine layer overlays fluvial deposit, indicating environmental changes from river channel to marsh or pond. We found evidence for cumulative vertical displacement on the top of pre-2011 artificial fill (1.7 m), river channel gravel layer (2.5 m), and bedrock (3.4 m). On the basis of sudden environmental changes from river to pond observed after the Iwaki earthquake due to subsided upstream area (Toda and Tsutsumi, 2013), we interpret that change in sedimentary facies from fluvial gravel to marsh or pond organic layer in the downthrown side corresponds to one of the past surface-rupturing earthquakes. Radiocarbon age yielded from the organic-rich unit suggests that one of the pre-2011 surface rupturing earthquakes occurred about 50,000 years ago. The amount of vertical displacement at one of the pre-2011 earthquakes (ca. 0.8 m) is significantly smaller than displacement at the Iwaki earthquake. Together with large coseismic slip at the 2011 event, it implies that the characteristic earthquake model cannot be simply applied to the faults largely influenced or directly triggered by huge megathrust earthquakes nearby.

  2. Children and the San Fernando earthquake

    USGS Publications Warehouse

    Howard, S. J.

    1980-01-01

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

  3. Assessing Earthquake Risks in the Pacific Northwest

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2014-10-01

    Megaquakes, which are subduction earthquakes with magnitudes of 8 or greater, occur about every 500 years on average along the Cascadia Subduction Zone in the Pacific Northwest. The earthquakes and related tsunamis can cause enormous damage. However, they may not be the most urgent seismic threat in the region, according to John Clague, a professor and expert on natural hazards at Simon Fraser University (SFU) in British Columbia.

  4. Source processes of the 1949 Olympia, Washington and other Cascadia intraslab earthquakes

    NASA Astrophysics Data System (ADS)

    Ichinose, G. A.; Somerville, P. G.; Thio, H.

    2004-12-01

    Cascadia intraslab earthquakes have occurred frequently including in 1949 (M 7), 1965 (M 6.9), and 2001 (Mw 6.8) and the hazard they pose is equal to other seismic sources for time scales relevant to retrofitting (50%PE in 75 yrs). Reexamination of historical earthquakes and analysis of broadband seismograms from new earthquakes improves strong motion prediction more than stochastic scenarios and provides a better understanding in how stress is released in the subducting slab relative to external tectonic forces and local dehydration. Reanalysis of the 1949 Olympia earthquake using digitized seismograms collected by Barker and Langston [1987], Wiest et al. [2004], long-period WWSSN data from College, Alaska, Bogotá, Columbia, and Pasadena, California, has yielded a normal-slip mechanism that fits all the available data with ˜ E-W extensional-axis. This mechanism better resembles those from previous Puget Sound intraslab earthquakes. The earthquake ruptured southward along a plane with 170\\deg strike and 70\\deg dip. The hypocenter depth is 60 km with a total Mo of 1.9\\times1026 dyne-cm (Mw 6.78). We inverted teleseismic body waves to determine the mechanism and rupture pattern in space and time using a time-domain iterative inversion process. We limited the number of unknowns by assuming only 2 subevents and performed a grid search on the remaining variables including hypocenter depth, rupture direction, subevent rise time and rupture velocity. A rise time of 3 s best fits the frequency content of the waveforms but there is no resolution of rupture velocity with this dataset so we assume 3.5 km/s. The total moment is typically lower because of stricter model assumptions and the use of band limited data. The amplitudes from the Pasadena 1-90 s Benioff records indicate a higher Mw ˜ 6.8 when compared to those from the 2001 Nisqually earthquake convolved with a similar response. We show from similar analyses of this and other intraslab earthquakes that they have significantly smaller asperity areas relative to other types of earthquakes with the same seismic moment originally identified by Asano et al. [2003] and Ichinose et al. [2004].

  5. Speeding earthquake disaster relief

    USGS Publications Warehouse

    Mortensen, Carl; Donlin, Carolyn; Page, Robert A.; Ward, Peter

    1995-01-01

    In coping with recent multibillion-dollar earthquake disasters, scientists and emergency managers have found new ways to speed and improve relief efforts. This progress is founded on the rapid availability of earthquake information from seismograph networks.

  6. Earthquakes for Kids

    MedlinePlus

    ... Education FAQ Earthquake Glossary For Kids Prepare Google Earth/KML Files Earthquake Summary Posters Photos Publications Share ... for Education FAQ EQ Glossary For Kids Google Earth/KML Files EQ Summary Posters Photos Publications Monitoring ...

  7. Earthquakes: hydrogeochemical precursors

    USGS Publications Warehouse

    Ingebritsen, Steven E.; Manga, Michael

    2014-01-01

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

  8. [Osmolality of frequently consumed beverages].

    PubMed

    Dini, Elizabeth; De Abreu, Jorge; López, Emeris

    2004-12-01

    The objective of this work was to determine the osmolality of beverages frequently consumed by children and adolescents due to the scarce information available in our country. The samples were grouped as follows: milks; refreshments; beverages based on fruits, vegetables, cereals, and tubers; sport drinks; energizing drinks; oral rehydrating solutions; reconstituted drinks and infusions. A vapor pressure digital osmometer was used, five samples of each beverage from different lots were analyzed. Four osmolality determinations were made on each sample and the average of such values was calculated. When the variation coefficient of the osmolality measurements of the five samples was higher than 10%, five additional samples were analyzed. As many samples as possible were used with breast milk in the time period of the study. Osmolality averages, standard deviation, and the osmolality confidence intervals (95% reliability) were calculated. The osmolality (mmol/kg) of breast milk and that of cow milk were between 273 and 389; refreshments, white, black and flavored colas, and malts ranged between 479-811; and soda and light drinks: 44-62; fresh fruit and commercial drinks (coconut, peach, apple, orange, pear, pineapple, grape, plum, tamarind): 257-1152 and light juices: 274; sports beverages: 367; energizing drinks: 740; drinks based on vegetables and cereals: 213-516; oral rehydrating solutions: 236-397; reconstituted drinks: 145; infusions: 25. Beverages with adequate osmolality levels for children were: milks, light refreshments, soda, fresh and light juices, oral rehydrating, soy, and reconstituted drinks and infusions. PMID:15602899

  9. Combined GPS and InSAR models of postseismic deformation from the Northridge Earthquake

    NASA Technical Reports Server (NTRS)

    Donnellan, A.; Parker, J. W.; Peltzer, G.

    2002-01-01

    Models of combined Global Positioning System and Interferometric Synthetic Aperture Radar data collected in the region of the Northridge earthquake indicate that significant afterslip on the main fault occurred following the earthquake.

  10. Automatic recognition of seismic intensity based on RS and GIS: a case study in Wenchuan Ms8.0 earthquake of China.

    PubMed

    Zhang, Qiuwen; Zhang, Yan; Yang, Xiaohong; Su, Bin

    2014-01-01

    In recent years, earthquakes have frequently occurred all over the world, which caused huge casualties and economic losses. It is very necessary and urgent to obtain the seismic intensity map timely so as to master the distribution of the disaster and provide supports for quick earthquake relief. Compared with traditional methods of drawing seismic intensity map, which require many investigations in the field of earthquake area or are too dependent on the empirical formulas, spatial information technologies such as Remote Sensing (RS) and Geographical Information System (GIS) can provide fast and economical way to automatically recognize the seismic intensity. With the integrated application of RS and GIS, this paper proposes a RS/GIS-based approach for automatic recognition of seismic intensity, in which RS is used to retrieve and extract the information on damages caused by earthquake, and GIS is applied to manage and display the data of seismic intensity. The case study in Wenchuan Ms8.0 earthquake in China shows that the information on seismic intensity can be automatically extracted from remotely sensed images as quickly as possible after earthquake occurrence, and the Digital Intensity Model (DIM) can be used to visually query and display the distribution of seismic intensity. PMID:24688445

  11. Automatic Recognition of Seismic Intensity Based on RS and GIS: A Case Study in Wenchuan Ms8.0 Earthquake of China

    PubMed Central

    Zhang, Yan; Su, Bin

    2014-01-01

    In recent years, earthquakes have frequently occurred all over the world, which caused huge casualties and economic losses. It is very necessary and urgent to obtain the seismic intensity map timely so as to master the distribution of the disaster and provide supports for quick earthquake relief. Compared with traditional methods of drawing seismic intensity map, which require many investigations in the field of earthquake area or are too dependent on the empirical formulas, spatial information technologies such as Remote Sensing (RS) and Geographical Information System (GIS) can provide fast and economical way to automatically recognize the seismic intensity. With the integrated application of RS and GIS, this paper proposes a RS/GIS-based approach for automatic recognition of seismic intensity, in which RS is used to retrieve and extract the information on damages caused by earthquake, and GIS is applied to manage and display the data of seismic intensity. The case study in Wenchuan Ms8.0 earthquake in China shows that the information on seismic intensity can be automatically extracted from remotely sensed images as quickly as possible after earthquake occurrence, and the Digital Intensity Model (DIM) can be used to visually query and display the distribution of seismic intensity. PMID:24688445

  12. Active tectonics and earthquake sources in the epicentral area of the 1857 Basilicata earthquake (southern Italy)

    NASA Astrophysics Data System (ADS)

    Cello, G.; Tondi, E.; Micarelli, L.; Mattioni, L.

    2003-09-01

    The 1857 Basilicata earthquake (Imax=XI MCS; Me=6.9) is one of the most destructive events that occurred in peninsular Italy; shaking effects and ground breaks were recorded over a large area extending from the Vallo di Diano (Campania) to the Val d'Agri (Basilicata) for a length of about 60 km and with a width of more than 10 km. Within this seismogenic belt, only another strong earthquake, with maximum intensities in the range of X MCS (Me=6.4), occurred in 1561. In the epicentral area of the 1857 earthquake, two regional fault systems (i.e. the Val d'Agri and the Vallo di Diano fault systems) offset the main features of the southern Apennines fold and thrust belt; both systems show evidence of activity during Pleistocene times. The Vallo di Diano Fault System (DIFS) includes mostly NW-SE and WNW-ESE trending faults displaying long-term displacements of a few hundred meters; slip data from the latter faults record a kinematic transition from almost pure normal motion to dextral/oblique motion, whereas the NW-SE oriented faults are mostly dominated by normal/transtensional (sinistral) motion. The Val d'Agri Fault System (VAFS) is characterized by fault zones of different size; it is a kinematically coherent system including roughly N120 trending left-lateral strike-slip faults and N090-N100 trending left-lateral transtensional faults. Inversion of fault slip data indicates that the stress field conditions responsible for the genesis and evolution of the two fault systems are quite different, with ?1 being: (1) sub-horizontal and WSW-ENE trending, in the case of the VAFS, and (2) sub-vertical, in the case of the DIFS. However, the two fault systems are characterized by a roughly N-S oriented extension, and by R-values indicating that ?1? ?2>> ?3. This suggests the possibility that, in these areas, permutations between the principal maximum and intermediate axes of the stress ellipsoid may have frequently occurred during the faulting process. In this paper, we present new data for both the VAFS and DIFS and discuss the inferred modes of interaction between the two fault systems; this, in turn, suggests possible implications for seismic hazard analyses (SHA) in this sector of the southern Apennines.

  13. Land subsidence of clay deposits after the Tohoku-Pacific Ocean Earthquake

    NASA Astrophysics Data System (ADS)

    Yasuhara, K.; Kazama, M.

    2015-11-01

    Extensive infrastructure collapse resulted from the cataclysmic earthquake that struck off the eastern coast of Japan on 11 March 2011 and from its consequent gigantic tsunami, affecting not only the Tohoku region but also the Kanto region. Among the geological and geotechnical processes observed, land subsidence occurring in both coastal and inland areas and from Tohoku to Kanto is an extremely important issue that must be examined carefully. This land subsidence is classifiable into three categories: (i) land sinking along the coastal areas because of tectonic movements, (ii) settlement of sandy deposits followed by liquefaction, and (iii) long-term post-earthquake recompression settlement in soft clay caused by dissipation of excess pore pressure. This paper describes two case histories of post-earthquake settlement of clay deposits from among the three categories of ground sinking and land subsidence because such settlement has been frequently overlooked in numerous earlier earthquakes. Particularly, an attempt is made to propose a methodology for predicting such settlement and for formulating remedial or responsive measures to mitigate damage from such settlement.

  14. Re-evaluation Of The Shallow Seismicity On Mt Etna Applying Probabilistic Earthquake Location Algorithms.

    NASA Astrophysics Data System (ADS)

    Tuve, T.; Mostaccio, A.; Langer, H. K.; di Grazia, G.

    2005-12-01

    A recent research project carried out together with the Italian Civil Protection concerns the study of amplitude decay laws in various areas on the Italian territory, including Mt Etna. A particular feature of seismic activity is the presence of moderate magnitude earthquakes causing frequently considerable damage in the epicentre areas. These earthquakes are supposed to occur at rather shallow depth, no more than 5 km. Given the geological context, however, these shallow earthquakes would origin in rather weak sedimentary material. In this study we check the reliability of standard earthquake location, in particular with respect to the calculated focal depth, using standard location methods as well as more advanced approaches such as the NONLINLOC software proposed by Lomax et al. (2000) using it with its various options (i.e., Grid Search, Metropolis-Gibbs and Oct-Tree) and 3D velocity model (Cocina et al., 2005). All three options of NONLINLOC gave comparable results with respect to hypocenter locations and quality. Compared to standard locations we note a significant improve of location quality and, in particular a considerable difference of focal depths (in the order of 1.5 - 2 km). However, we cannot find a clear bias towards greater or lower depth. Further analyses concern the assessment of the stability of locations. For this purpose we carry out various Monte Carlo experiments perturbing travel time reading randomly. Further investigations are devoted to possible biases which may arise from the use of an unsuitable velocity model.

  15. Does Geothermal Energy Production Cause Earthquakes in the Geysers Region of Northern California?

    NASA Astrophysics Data System (ADS)

    Grove, K.; Bailey, C.; Sotto, M.; Yu, M.; Cohen, M.

    2003-12-01

    The Geysers region is located in Sonoma County, several hours north of San Francisco. At this location, hot magma beneath the surface heats ground water and creates steam that is used to make electricity. Since 1997, 8 billion gallons of treated wastewater have been injected into the ground, where the water becomes hot and increases the amount of thermal energy that can be produced. Frequent micro-earthquakes (up to magnitude 4.5) occur in the region and seem to be related to the geothermal energy production. The region is mostly uninhabited, except for several small towns such as Anderson Springs, where people have been extremely concerned about potential damage to their property. The energy companies are planning to double the amount of wastewater injected into the ground and to increase their energy production. Geothermal energy is important because it is better for the environment than burning coal, oil, or gas. Air and water pollution, which have negative impacts on living things, are reduced compared to power plants that generate electricity by burning fossil fuels. We have studied the frequency and magnitude of earthquakes that have occurred in the region since the early 1970s and that are occurring today. We used software to analyze the earthquakes and to look for patterns related to water injection and energy production. We are interested in exploring ways that energy production can be continued without having negative impacts on the people in the region.

  16. Remote monitoring of the earthquake cycle using satellite radar interferometry

    NASA Astrophysics Data System (ADS)

    Wright, Tim J.

    2002-12-01

    The earthquake cycle is poorly understood. Earthquakes continue to occur on previously unrecognized faults. Earthquake prediction seems impossible. These remain the facts despite nearly 100 years of intensive study since the earthquake cycle was first conceptualized. Using data acquired from satellites in orbit 800 km above the Earth, a new technique, radar interferometry (InSAR), has the potential to solve these problems. For the first time, detailed maps of the warping of the Earth's surface during the earthquake cycle can be obtained with a spatial resolution of a few tens of metres and a precision of a few millimetres. InSAR does not need equipment on the ground or expensive field campaigns, so it can gather crucial data on earthquakes and the seismic cycle from some of the remotest areas of the planet. In this article, I review some of the remarkable observations of the earthquake cycle already made using radar interferometry and speculate on breakthroughs that are tantalizingly close.

  17. 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.

  18. Possible seasonality in large deep-focus earthquakes

    NASA Astrophysics Data System (ADS)

    Zhan, Zhongwen; Shearer, Peter M.

    2015-09-01

    Large deep-focus earthquakes (magnitude > 7.0, depth > 500 km) have exhibited strong seasonality in their occurrence times since the beginning of global earthquake catalogs. Of 60 such events from 1900 to the present, 42 have occurred in the middle half of each year. The seasonality appears strongest in the northwest Pacific subduction zones and weakest in the Tonga region. Taken at face value, the surplus of northern hemisphere summer events is statistically significant, but due to the ex post facto hypothesis testing, the absence of seasonality in smaller deep earthquakes, and the lack of a known physical triggering mechanism, we cannot rule out that the observed seasonality is just random chance. However, we can make a testable prediction of seasonality in future large deep-focus earthquakes, which, given likely earthquake occurrence rates, should be verified or falsified within a few decades. If confirmed, deep earthquake seasonality would challenge our current understanding of deep earthquakes.

  19. A Decade of Giant Earthquakes - What does it mean?

    SciTech Connect

    Wallace, Terry C. Jr.

    2012-07-16

    On December 26, 2004 the largest earthquake since 1964 occurred near Ache, Indonesia. The magnitude 9.2 earthquake and subsequent tsunami killed a quarter of million people; it also marked the being of a period of extraordinary seismicity. Since the Ache earthquake there have been 16 magnitude 8 earthquakes globally, including 2 this last April. For the 100 years previous to 2004 there was an average of 1 magnitude 8 earthquake every 2.2 years; since 2004 there has been 2 per year. Since magnitude 8 earthquakes dominate global seismic energy release, this period of seismicity has seismologist rethinking what they understand about plate tectonics and the connectivity between giant earthquakes. This talk will explore this remarkable period of time and its possible implications.

  20. Redefining Earthquakes and the Earthquake Machine

    ERIC Educational Resources Information Center

    Hubenthal, Michael; Braile, Larry; Taber, John

    2008-01-01

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

  1. Redefining Earthquakes and the Earthquake Machine

    ERIC Educational Resources Information Center

    Hubenthal, Michael; Braile, Larry; Taber, John

    2008-01-01

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

  2. New earthquake catalog reexamines Hawaii's seismic history

    NASA Astrophysics Data System (ADS)

    Wright, Thomas L.; Klein, Fred W.

    On April 2,1868, an earthquake of magnitude 7.9 occurred beneath the southern part of the island of Hawaii. The quake, which was felt throughout all of the Hawaiian Islands, had a Modified Mercalli (MM) intensity of XII near its source.The destruction caused by a quake that large is nearly complete. A landslide triggered by the quake buried a small village, killing 31 people, and a tsunami that swept over coastal settlements added to the death toll.We know as much as we do about this and other early earthquakes thanks to detailed records kept by Hawaiian missionaries, including the remarkable diary maintained by the Lyman family that documented every earthquake felt at their home in Hilo between 1833 and 1917 [Wyss et al., 1992].Our analysis of these and other historical records indicates that Hawaii was at least as intensely seismic in the 19th century and first half of the 20th century as in its more recent past, with 26 M ≥6.0 earthquakes occurring from 1823 to 1903 and 20 M ≥6.0 earthquakes from 1904 to 1959. Just five M ≥6.0 earthquakes occurred from 1960 to 1999. The potential damage caused by a repeat of some of the larger historic events could be catastrophic today

  3. New earthquake catalog reexamines Hawaii's seismic history

    USGS Publications Warehouse

    Wright, Thomas L.; Klein, Fred W.

    2000-01-01

    On April 2,1868, an earthquake of magnitude 7.9 occurred beneath the southern part of the island of Hawaii. The quake, which was felt throughout all of the Hawaiian Islands, had a Modified Mercalli (MM) intensity of XII near its source.The destruction caused by a quake that large is nearly complete. A landslide triggered by the quake buried a small village, killing 31 people, and a tsunami that swept over coastal settlements added to the death toll. We know as much as we do about this and other early earthquakes thanks to detailed records kept by Hawaiian missionaries, including the remarkable diary maintained by the Lyman family that documented every earthquake felt at their home in Hilo between 1833 and 1917 [Wyss et al., 1992].Our analysis of these and other historical records indicates that Hawaii was at least as intensely seismic in the 19th century and first half of the 20th century as in its more recent past, with 26 M ≥6.0 earthquakes occurring from 1823 to 1903 and 20 M ≥6.0 earthquakes from 1904 to 1959. Just five M ≥6.0 earthquakes occurred from 1960 to 1999. The potential damage caused by a repeat of some of the larger historic events could be catastrophic today.

  4. Earthquake Prognosis With Applied Microseism.

    NASA Astrophysics Data System (ADS)

    Ahmedov, N.; Nagiyev, A.

    Earthquakes are the most dangerous natural catastrophy in terms of numerous casualties, amount of damages, areal coverage and difficulties associated with a need to provide secure measures. Inability to forecast these events makes the situation worse due to the following circumstances:-their buried focuses are invisible in the subsurface, they occur suddenly as a thunder, and some tens of the seconds later they leave devastated areas and casualties of tens of thousands of people. Currently earthquake forecausting is actually absolutely inefficient. Microseism application is one of the possible ways to forecast earthquakes. These small oscillation of up-going low-ampitude, irregular wawes observed on seismograms are refered to as microseism. Having been different from earhquakes itself, they are continuous, that is, have no origin coordinate on time axis. Their occurence is associated with breakers observed along shorelines, strong wind and hurricane patterns and so on. J.J.Linch has discovered a new tool to monitor hurricane motion trend over the seas with applied microseism recorded at ad hocstations. Similar to these observations it became possible to monitor the formation of the earthquake focuses based on correlation between low-frequency horizontal ahannels'N-S and E-W components. Microseism field and preceding abnormal variations monitoring data derived from "Cherepaha" 3M and 6/12 device enable to draw out some systematic trend in amplitude/frecuency domain. This relationship observed in a certain frequency range made it possible to define the generation of earthquake focuses with regard to the monitoring station. This variation trend was observed while Turkish and Iranian events happened during 1990,1992, and 1997. It is suggested to be useful to verify these effects in other regions to further correlate available data and work out common forecausting criteria.

  5. Anomalous Schumann resonance observed in China, possibly associated with Honshu, Japan Earthquake

    NASA Astrophysics Data System (ADS)

    Ouyang, X. Y.; Zhang, X. M.; Shen, X. H.; Miao, Y. Q.

    2012-04-01

    Schumann resonance (hereafter SR) occurs in the cavity between the Earth and the ionosphere, and it is originated by the global lightning activities [1]. Some recent publications showed that anomalous SR phenomena may occur before major earthquakes [2-4]. Considering good prospects for the application of SR in Earthquake monitoring, we have established four observatories in Yunnan province, a region with frequent seismicity in the southwest of China. Our instruments can provide three components of magnetic field in 0-30 Hz, including BNS(North-South component), BEW(East-West component) and BV (Vertical component). The sample frequency is 100 Hz. In this research, we use high quality data recorded at Yongsheng observatory (geographic coordinates: 26.7° N, 100.77°E) to analyze SR phenomena to find out anomalous effects possibly related with the Ms9.0 Earthquake (epicenter: 38.297° N, 142.372° E) near the east coast of Honshu, Japan on 11 March 2011. We select the data 15 days before and after the earthquake. SR in BNS and SR in BEWappear different in background characteristics. Frequencies of four SR modes in BNSare generally higher than that in BEW. Amplitude of SR in BNSis strong at around 05:00 LT, 15:00 LT and 23:00 LT of the day, while amplitude of SR in BEW is just intense around 16:00 LT, corresponding to about 08:00 UT. Because American, African and Asian thunderstorm centers play their dominant roles respectively in the intervals of 21:00UT±1h, 15:00UT±1h and 08:00UT±1h [1, 3], we can see that SR in BEWis most sensitive to signals from Asian center and SR in BNS is in good response to three centers. SR in BNS and SR in BEW have presented different features in the aspect of anomalous effects related with earthquakes. BEW component gives us a clear picture of anomalous SR phenomena, which are characterized by increase in amplitude of four SR modes and increase in frequency at first SR mode several days before the earthquake. The amplitude of four SR modes began to increase four days before Honshu earthquake (7th March). And this continued to the day of the earthquake (11th March). Then it fell to the usual intensity after the earthquake (12th March). The frequency at first SR mode in BEW unconventionally exceeded the first mode frequency in BNS with an enhancement of 0.7 Hz on 8th and 9th March. We did not find similar anomalous effects in BNS. The anomalous effects in BEW may be caused by interference between direct path from Asian center to the observatory and disturbed path scattered by the perturbation in the ionosphere over Honshu. More detailed analysis is going on. 1. Nickolaenko A P and Hayakawa M, Resonances in the Earth-ionosphere cavity. 2002: Kluwer Academic Pub. 2. Hayakawa M, Ohta K, Nickolaenko A P, et al. Anomalous effect in Schumann resonance phenomena observed in Japan, possibly associated with the Chi-chi earthquake in Taiwan. Annales geophysicae,2005. pp. 1335-1346. 3. Hayakawa M, Nickolaenko A P, Sekiguchi M, et al., Anomalous ELF phenomena in the Schumann resonance band as observed at Moshiri (Japan) in possible association with an earthquake in Taiwan. Nat. Hazards Earth Syst. Sci, 2008. 8(6): p. 1309-1316. 4. Ohta K, Izutsu J, and Hayakawa M, Anomalous excitation of Schumann resonances and additional anomalous resonances before the 2004 Mid-Niigata prefecture earthquake and the 2007 Noto Hantou Earthquake. Physics and Chemistry of the Earth, Parts A/B/C, 2009. 34(6-7): p. 441-448.

  6. Earthquake and Schools. [Videotape].

    ERIC Educational Resources Information Center

    Federal Emergency Management Agency, Washington, DC.

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

  7. Real Earthquakes, Real Learning

    ERIC Educational Resources Information Center

    Schomburg, Aaron

    2003-01-01

    One teacher took her class on a year long earthquake expedition. The goal was to monitor the occurrences of real earthquakes during the year and mark their locations with push pins on a wall-sized world map in the hallway outside the science room. The purpose of the project was to create a detailed picture of the earthquakes that occurred…

  8. Children's Ideas about Earthquakes

    ERIC Educational Resources Information Center

    Simsek, Canan Lacin

    2007-01-01

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

  9. Frequent Hemodialysis Fistula Infectious Complications

    PubMed Central

    Lok, Charmaine E.; Sontrop, Jessica M.; Faratro, Rose; Chan, Christopher T.; Zimmerman, Deborah Lynn

    2014-01-01

    Background Few studies have examined if infectious arteriovenous access complications vary with the cannulation technique and whether this is modified by dialysis frequency. We compared the infection rate between fistulas cannulated using buttonhole versus stepladder techniques for patients treated with short daily (SDH) or nocturnal hemodialysis at home (NHD). We also compared patients receiving conventional intermittent hemodialysis (CIHD) using stepladder cannulation. Methods Data were prospectively collected from 631 patients dialyzed with a fistula from 2001 to 2010 (Toronto and Ottawa, Canada). We compared the person-time incidence rate of bacteremia and local fistula infections using the exact binomial test. Results Forty-six (7.3%) patients received SDH (?5 sessions/week, 2-4 h/session), 128 (20.3%) NHD (?4 sessions/week, ?5 h/session) and 457 (72%) CIHD (3 sessions/week, ?4 h/session). Fifty percent of SDH and 72% of NHD patients used the buttonhole technique. There were 39 buttonhole-related bacteremias (rate: 0.196/1,000 fistula days) and at least 2 local buttonhole site infections. Staphylococcus aureus accounted for 85% of the bacteremias. There were 5 (13%) infection-related hospitalizations and 3 (10%) serious metastatic infections, including fistula loss. In comparison, there was 1 possible fistula-related infection in CIHD during follow-up (rate: 0.002/1,000 fistula days). Conclusions The rate of buttonhole-related infections was high among patients on frequent hemodialysis and more than 50 times greater than that among patients on CIHD with the stepladder technique. Most bacteremias were due to S. aureus with serious consequences. The risks and benefits of buttonhole cannulation require individual consideration with careful monitoring, prophylaxis and management. PMID:25473405

  10. Probing failure susceptibilities of earthquake faults using small-quake tidal correlations.

    PubMed

    Brinkman, Braden A W; LeBlanc, Michael; Ben-Zion, Yehuda; Uhl, Jonathan T; Dahmen, Karin A

    2015-01-01

    Mitigating the devastating economic and humanitarian impact of large earthquakes requires signals for forecasting seismic events. Daily tide stresses were previously thought to be insufficient for use as such a signal. Recently, however, they have been found to correlate significantly with small earthquakes, just before large earthquakes occur. Here we present a simple earthquake model to investigate whether correlations between daily tidal stresses and small earthquakes provide information about the likelihood of impending large earthquakes. The model predicts that intervals of significant correlations between small earthquakes and ongoing low-amplitude periodic stresses indicate increased fault susceptibility to large earthquake generation. The results agree with the recent observations of large earthquakes preceded by time periods of significant correlations between smaller events and daily tide stresses. We anticipate that incorporating experimentally determined parameters and fault-specific details into the model may provide new tools for extracting improved probabilities of impending large earthquakes. PMID:25625338

  11. Earthquake location in island arcs

    USGS Publications Warehouse

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

    1982-01-01

    A comprehensive data set of selected teleseismic P-wave arrivals and local-network P- and S-wave arrivals from large earthquakes occurring at all depths within a small section of the central Aleutians is used to examine the general problem of earthquake location in island arcs. Reference hypocenters for this special data set are determined for shallow earthquakes from local-network data and for deep earthquakes from combined local and teleseismic data by joint inversion for structure and location. The high-velocity lithospheric slab beneath the central Aleutians may displace hypocenters that are located using spherically symmetric Earth models; the amount of displacement depends on the position of the earthquakes with respect to the slab and on whether local or teleseismic data are used to locate the earthquakes. Hypocenters for trench and intermediate-depth events appear to be minimally biased by the effects of slab structure on rays to teleseismic stations. However, locations of intermediate-depth events based on only local data are systematically displaced southwards, the magnitude of the displacement being proportional to depth. Shallow-focus events along the main thrust zone, although well located using only local-network data, are severely shifted northwards and deeper, with displacements as large as 50 km, by slab effects on teleseismic travel times. Hypocenters determined by a method that utilizes seismic ray tracing through a three-dimensional velocity model of the subduction zone, derived by thermal modeling, are compared to results obtained by the method of joint hypocenter determination (JHD) that formally assumes a laterally homogeneous velocity model over the source region and treats all raypath anomalies as constant station corrections to the travel-time curve. The ray-tracing method has the theoretical advantage that it accounts for variations in travel-time anomalies within a group of events distributed over a sizable region of a dipping, high-velocity lithospheric slab. In application, JHD has the practical advantage that it does not require the specification of a theoretical velocity model for the slab. Considering earthquakes within a 260 km long by 60 km wide section of the Aleutian main thrust zone, our results suggest that the theoretical velocity structure of the slab is presently not sufficiently well known that accurate locations can be obtained independently of locally recorded data. Using a locally recorded earthquake as a calibration event, JHD gave excellent results over the entire section of the main thrust zone here studied, without showing a strong effect that might be attributed to spatially varying source-station anomalies. We also calibrated the ray-tracing method using locally recorded data and obtained results generally similar to those obtained by JHD. ?? 1982.

  12. Operational earthquake forecasting can enhance earthquake preparedness

    USGS Publications Warehouse

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

    2014-01-01

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

  13. 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. PMID:25013073

  14. Frequent Video Game Players Resist Perceptual Interference

    PubMed Central

    Berard, Aaron V.; Cain, Matthew S.; Watanabe, Takeo; Sasaki, Yuka

    2015-01-01

    Playing certain types of video games for a long time can improve a wide range of mental processes, from visual acuity to cognitive control. Frequent gamers have also displayed generalized improvements in perceptual learning. In the Texture Discrimination Task (TDT), a widely used perceptual learning paradigm, participants report the orientation of a target embedded in a field of lines and demonstrate robust over-night improvement. However, changing the orientation of the background lines midway through TDT training interferes with overnight improvements in overall performance on TDT. Interestingly, prior research has suggested that this effect will not occur if a one-hour break is allowed in between the changes. These results have suggested that after training is over, it may take some time for learning to become stabilized and resilient against interference. Here, we tested whether frequent gamers have faster stabilization of perceptual learning compared to non-gamers and examined the effect of daily video game playing on interference of training of TDT with one background orientation on perceptual learning of TDT with a different background orientation. As a result, we found that non-gamers showed overnight performance improvement only on one background orientation, replicating previous results with the interference in TDT. In contrast, frequent gamers demonstrated overnight improvements in performance with both background orientations, suggesting that they are better able to overcome interference in perceptual learning. This resistance to interference suggests that video game playing not only enhances the amplitude and speed of perceptual learning but also leads to faster and/or more robust stabilization of perceptual learning. PMID:25807394

  15. Precursory seismicity associated with frequent, large ice avalanches on Iliamna Volcano, Alaska, USA

    USGS Publications Warehouse

    Caplan-Auerbach, Jacqueline; Huggel, C.

    2007-01-01

    Since 1994, at least six major (volume>106 m3) ice and rock avalanches have occurred on Iliamna volcano, Alaska, USA. Each of the avalanches was preceded by up to 2 hours of seismicity believed to represent the initial stages of failure. Each seismic sequence begins with a series of repeating earthquakes thought to represent slip on an ice-rock interface, or between layers of ice. This stage is followed by a prolonged period of continuous ground-shaking that reflects constant slip accommodated by deformation at the glacier base. Finally the glacier fails in a large avalanche. Some of the events appear to have entrained large amounts of rock, while others comprise mostly snow and ice. Several avalanches initiated from the same source region, suggesting that this part of the volcano is particularly susceptible to failure, possibly due to the presence of nearby fumaroles. Although thermal conditions at the time of failure are not well constrained, it is likely that geothermal energy causes melting at the glacier base, promoting slip and culminating in failure. The frequent nature and predictable failure sequence of Iliamna avalanches makes the volcano an excellent laboratory for the study of ice avalanches. The prolonged nature of the seismic signal suggests that warning may one day be given for similar events occurring in populated regions.

  16. Loma Prieta earthquake, October 17, 1989, Santa Cruz County, California

    SciTech Connect

    McNutt, S.

    1990-01-01

    On Tuesday, October 17, 1989 at 5:04 p.m. Pacific Daylight Time, a magnitude 7.1 earthquake occurred on the San Andreas fault 10 miles northeast of Santa Cruz. This earthquake was the largest earthquake to occur in the San Francisco Bay area since 1906, and the largest anywhere in California since 1952. The earthquake was responsible for 67 deaths and about 7 billion dollars worth of damage, making it the biggest dollar loss natural disaster in United States history. This article describes the seismological features of the earthquake, and briefly outlines a number of other geologic observations made during study of the earthquake, its aftershocks, and its effects. Much of the information in this article was provided by the U.S. Geological Survey (USGS).

  17. Frog Swarms: Earthquake Precursors or False Alarms?

    PubMed

    Grant, Rachel A; Conlan, Hilary

    2013-01-01

    In short-term earthquake risk forecasting, the avoidance of false alarms is of utmost importance to preclude the possibility of unnecessary panic among populations in seismic hazard areas. Unusual animal behaviour prior to earthquakes has been reported for millennia but has rarely been scientifically documented. Recently large migrations or unusual behaviour of amphibians have been linked to large earthquakes, and media reports of large frog and toad migrations in areas of high seismic risk such as Greece and China have led to fears of a subsequent large earthquake. However, at certain times of year large migrations are part of the normal behavioural repertoire of amphibians. News reports of "frog swarms" from 1850 to the present day were examined for evidence that this behaviour is a precursor to large earthquakes. It was found that only two of 28 reported frog swarms preceded large earthquakes (Sichuan province, China in 2008 and 2010). All of the reported mass migrations of amphibians occurred in late spring, summer and autumn and appeared to relate to small juvenile anurans (frogs and toads). It was concluded that most reported "frog swarms" are actually normal behaviour, probably caused by juvenile animals migrating away from their breeding pond, after a fruitful reproductive season. As amphibian populations undergo large fluctuations in numbers from year to year, this phenomenon will not occur on a yearly basis but will depend on successful reproduction, which is related to numerous climatic and geophysical factors. Hence, most large swarms of amphibians, particularly those involving very small frogs and occurring in late spring or summer, are not unusual and should not be considered earthquake precursors. In addition, it is likely that reports of several mass migration of small toads prior to the Great Sichuan Earthquake in 2008 were not linked to the subsequent M = 7.9 event (some occurred at a great distance from the epicentre), and were probably co-incidence. Statistical analysis of the data indicated frog swarms are unlikely to be connected with earthquakes. Reports of unusual behaviour giving rise to earthquake fears should be interpreted with caution, and consultation with experts in the field of earthquake biology is advised. PMID:26479746

  18. Sichuan Earthquake in China

    NASA Technical Reports Server (NTRS)

    2008-01-01

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

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

  19. A cross section of the Los Angeles Area: Seismically active fold and thrust belt, The 1987 Whittier Narrows earthquake, and earthquake hazard

    NASA Astrophysics Data System (ADS)

    Davis, Thomas L.; Namson, Jay; Yerkes, Robert F.

    1989-07-01

    Retrodeformable cross sections across the Los Angeles area interpret the Pliocene to Quaternary deformation to be a developing basement-involved fold and thrust belt. The fold and thrust belt is seismically active as evidenced by the 1987 Whittier Narrows earthquake (ML = 5.9) and the 1971 San Fernando earthquake (MW = 6.6). The structural geology of the Los Angeles area is dominated by three major compressional uplift trends: (1) the Palos Verdes anticlinorium and western shelf, (2) the Santa Monica Mountains anticlinorium, and (3) the Verdugo Mountains-San Rafael Hills and the San Gabriel Mountains. These trends result from major thrust ramps off a detachment(s) at 10-15 km depth. Thrusts of the Verdugo Mountains-San Rafael Hills and the San Gabriel Mountains reach the surface; the other two uplifts are associated with blind thrusts. Compressional seismicity is concentrated along these thrust ramps. The 1987 Whittier Narrows earthquake probably occurred on the Elysian Park thrust which underlies the Santa Monica Mountains anticlinorium. The thrust interpretation accounts for the geometry of the anticlinorium, the seismological characteristics of the earthquake, and the geometry of coseismic uplift. The earthquake and aftershocks occurred within a structurally complex, narrow zone of Miocene and Pliocene northwest trending faults that cross the anticlinorium at a high angle. These northwest trending faults are interpreted to be reactivated faults now behaving as tears in the Elysian Park thrust and not the result of active right-lateral deformation extending into the Whittier Narrows area. Our analysis suggests the Whittier Narrows earthquake sequence occurred within a structurally weakened zone along the Elysian Park thrust. We also suggest that the Whittier fault is not an important Quaternary structure and may not be seismogenic. The regional cross section is a nonunique solution, and other possible solutions are considered. Multiple solutions arise from the presence of two intersecting compressional belts in the Los Angeles area: the Transverse Ranges and the northern Peninsular Ranges. The belts may be due to one or more regional detachments and the northern Peninsular Ranges may be northeast or southwest vergent. The deformed top of the crystalline basement along the regional cross section requires a minimum of 15.0 km of north-south convergence between the Palos Verdes Hills and the San Andreas fault regardless of the structural solution. Restoration of our cross section solution requires 21.4 km of north-south convergence on top of the crystalline basement (including 6.4 km of slip continuing offshore to make structures of the continental borderland) and 29.7 km of convergence on the basal detachment. Geologic relationships suggest major shortening started between early and late Pliocene time (2.2-4.0 Ma) which yields a minimum convergence rate of 3.8-6.8 mm/yr between the Palos Verdes Hills and the San Andreas fault. Convergence rates for our solution range from 5.4 to 13.5 mm/yr between the edge of the continental borderland and the San Andreas fault. Slip rate estimates for the Elysian Park thrust along the eastern portion of the Santa Monica Mountains anticlinorium are 2.5-5.2 mm/yr. If the 1987 Whittier Narrows earthquake is the characteristic earthquake along the 170-km-long anticlinorium, then recurrence intervals are estimated to be 5.6-12.1 years. This recurrence is higher than the historic seismic record along the Santa Monica Mountains anticlinorium and suggests that (1) our slip rates are too high, (2) some crustal shortening is taken up aseismically, and/or (3) earthquakes larger than the 1987 Whittier Narrows earthquake will occur along the anticlinorium, but less frequently.

  20. Earthquake Stress Transfer within Continents: Migrating Earthquakes and Long Aftershock Sequences

    NASA Astrophysics Data System (ADS)

    Stein, S. A.; Liu, M.; Wang, H.

    2009-12-01

    Stress transfer after large earthquakes has different effects within continental plate interiors than at plate boundaries. These differences explain why the spatio-temporal patterns of earthquakes in the two environments are so different given that the physics of fault rupture is essentially the same. At plate boundaries, steady plate motion reloads faults quickly after large earthquakes. This tectonic reloading soon dominates all other stress effects including those due to earthquakes on other faults. As a result, fault segments produce quasi-periodic earthquakes. In contrast, after a large mid-continental earthquake, stress reaccumulates very slowly - if at all - on the fault that broke. Instead, the resulting stress changes can give rise to earthquakes on other faults that have been quiescent for a long time. As a result, continental seismicity is often episodic, temporally clustered, and migrate between faults over thousands of years. A striking example of this variability is in North China, where large (M>7) earthquakes have been frequent, but not a single one repeated in the same place since 1300 A.D. For similar reasons, aftershock sequences within continents can last hundreds of years. Aftershocks result from changes of stress and fault properties induced by the main shock. At a plate boundary, steady plate motion quickly reloads the fault after a large earthquake and overwhelms the effects of the main shock. Within continents, however, the faults are reloaded much more slowly, allowing aftershocks to continue much longer. The observed aftershock sequence lengths are consistent with a simple model based on rate-and-state fault friction that predicts that the length of aftershock sequences varies inversely with the fault loading rate. Recognizing the migration of large earthquakes and long aftershock sequences is crucial for seismic hazard assessment within continents. Because many small earthquakes are probably aftershocks, their locations are unlikely to indicate the timing or the locations of future large earthquakes. Moreover, because in the short term much of the seismic hazard results from aftershocks, which can be damaging, these aftershocks should not be removed in attempts to infer earthquake recurrence. In the longer term, relying unduly on recent seismicity to predict the locations of future large earthquakes will overestimate the hazard in some places and lead to surprises elsewhere.

  1. The effects of earthquake measurement concepts and magnitude anchoring on individuals' perceptions of earthquake risk

    USGS Publications Warehouse

    Celsi, R.; Wolfinbarger, M.; Wald, D.

    2005-01-01

    The purpose of this research is to explore earthquake risk perceptions in California. Specifically, we examine the risk beliefs, feelings, and experiences of lay, professional, and expert individuals to explore how risk is perceived and how risk perceptions are formed relative to earthquakes. Our results indicate that individuals tend to perceptually underestimate the degree that earthquake (EQ) events may affect them. This occurs in large part because individuals' personal felt experience of EQ events are generally overestimated relative to experienced magnitudes. An important finding is that individuals engage in a process of "cognitive anchoring" of their felt EQ experience towards the reported earthquake magnitude size. The anchoring effect is moderated by the degree that individuals comprehend EQ magnitude measurement and EQ attenuation. Overall, the results of this research provide us with a deeper understanding of EQ risk perceptions, especially as they relate to individuals' understanding of EQ measurement and attenuation concepts. ?? 2005, Earthquake Engineering Research Institute.

  2. Crowdsourced earthquake early warning

    PubMed Central

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

    2015-01-01

    Earthquake early warning (EEW) can reduce harm to people and infrastructure from earthquakes and tsunamis, but it has not been implemented in most high earthquake-risk regions because of prohibitive cost. Common consumer devices such as smartphones contain low-cost versions of the sensors used in EEW. Although less accurate than scientific-grade instruments, these sensors are globally ubiquitous. Through controlled tests of consumer devices, simulation of an Mw (moment magnitude) 7 earthquake on California’s Hayward fault, and real data from the Mw 9 Tohoku-oki earthquake, we demonstrate that EEW could be achieved via crowdsourcing. PMID:26601167

  3. Crowdsourced earthquake early warning.

    PubMed

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

    2015-04-01

    Earthquake early warning (EEW) can reduce harm to people and infrastructure from earthquakes and tsunamis, but it has not been implemented in most high earthquake-risk regions because of prohibitive cost. Common consumer devices such as smartphones contain low-cost versions of the sensors used in EEW. Although less accurate than scientific-grade instruments, these sensors are globally ubiquitous. Through controlled tests of consumer devices, simulation of an M w (moment magnitude) 7 earthquake on California's Hayward fault, and real data from the M w 9 Tohoku-oki earthquake, we demonstrate that EEW could be achieved via crowdsourcing. PMID:26601167

  4. Scaling of seismic memory with earthquake size

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

  5. Changes in Permeability Produced By Distant Earthquakes

    NASA Astrophysics Data System (ADS)

    Manga, M.; Wang, C. Y.; Shi, Z.

    2014-12-01

    Oscillations in stress, such as those created by earthquakes, can increase permeability and fluid mobility in geologic media. In natural systems, strain amplitudes as small as 10-6 can increase discharge in streams and springs, change the water level of wells, and enhance production from petroleum reservoirs. Enhanced permeability typically recovers to pre-stimulated values over a period of months to years. This presentation will review some of the observations that indicate that dynamic stresses produced by seismic waves change permeability. We use the response of a set of wells distributed throughout China to multiple large earthquakes to probe the relationship between earthquake-generated stresses and water-level changes in wells. We find that dynamic stresses dominate the responses at distances more than 1 fault length from the earthquake and that permeability changes may explain the water level changes. Regions with high deformation rates are most sensitive to seismic waves. We also consider the response of a large alluvial fan in Taiwan to the 1999 M7.5 Chi-Chi earthquake where there were sustained changes in groundwater temperature after the earthquake. Using groundwater flow models, we infer that permeability increased by an order of magnitude over horizontal scales of tens of km, and vertical scales of several km. Permeability returned to the pre-earthquake value over many months. As much as half the total transport in the fan occurs during the short time periods with enhanced permeability.

  6. Ice melting and earthquake suppression in Greenland

    NASA Astrophysics Data System (ADS)

    Olivieri, M.; Spada, G.

    2015-03-01

    It has been suggested that the Greenland ice sheet is the cause of earthquake suppression in the region. With few exceptions, the observed seismicity extends only along the continental margins of Greenland, which almost coincide with the ice sheet margin. This pattern has been put forward as further validation of the earthquake suppression hypothesis. In this review, new evidence in terms of ice melting, post-glacial rebound and earthquake occurrence is gathered and discussed to re-evaluate the connection between ice mass unloading and earthquake suppression. In Greenland, the spatio-temporal distribution of earthquakes indicates that seismicity is mainly confined to regions where the thick layer of ice is absent and where significant ice melting is presently occurring. A clear correlation between seismic activity and ice melting in Greenland is not found. However, earthquake locations and corresponding depth distributions suggest two distinct governing mechanisms: post-glacial rebound promotes moderate-size crustal earthquakes at Greenland's regional scale, while current ice melting promotes shallow low magnitude seismicity locally.

  7. The surface latent heat flux anomalies related to major earthquake

    NASA Astrophysics Data System (ADS)

    Jing, Feng; Shen, Xuhui; Kang, Chunli; Xiong, Pan; Hong, Shunying

    2011-12-01

    SLHF (Surface Latent Heat Flux) is an atmospheric parameter, which can describe the heat released by phase changes and dependent on meteorological parameters such as surface temperature, relative humidity, wind speed etc. There is a sharp difference between the ocean surface and the land surface. Recently, many studies related to the SLHF anomalies prior to earthquakes have been developed. It has been shown that the energy exchange enhanced between coastal surface and atmosphere prior to earthquakes can increase the rate of the water-heat exchange, which will lead to an obviously increases in SLHF. In this paper, two earthquakes in 2010 (Haiti earthquake and southwest of Sumatra in Indonesia earthquake) have been analyzed using SLHF data by STD (standard deviation) threshold method. It is shows that the SLHF anomaly may occur in interpolate earthquakes or intraplate earthquakes and coastal earthquakes or island earthquakes. And the SLHF anomalies usually appear 5-6 days prior to an earthquake, then disappear quickly after the event. The process of anomaly evolution to a certain extent reflects a dynamic energy change process about earthquake preparation, that is, weak-strong-weak-disappeared.

  8. Earthquake Observation through Groundwater Monitoring in South Korea

    NASA Astrophysics Data System (ADS)

    Piao, J.; Woo, N. C.

    2014-12-01

    According to previous researches, the influence of the some earthquakes can be detected by groundwater monitoring. Even in some countries groundwater monitoring is being used as an important tool to identify earthquake precursors and prediction measures. Thus, in this study we attempt to catch the anomalous changes in groundwater produced by earthquakes occurred in Korea through the National Groundwater Monitoring Network (NGMN). For observing the earthquake impacts on groundwater more effectively, from the National Groundwater Monitoring Network we selected 28 stations located in the five earthquake-prone zones in South Korea. And we searched the responses to eight earthquakes with M ≥2.5 which occurred in the vicinity of five earthquake-prone zones in 2012. So far, we tested the groundwater monitoring data (water-level, temperature and electrical conductivity). Those data have only been treated to remove barometric pressure changes. Then we found 29 anomalous changes, confirming that groundwater monitoring data can provide valuable information on earthquake effects. To identify the effect of the earthquake from mixture signals of water-level, other signals must be separated from the original data. Periodic signals will be separated from the original data using Fast Fourier Transform (FFT). After that we will attempt to separate precipitation effect, and determine if the anomalies were generated by earthquake or not.

  9. Intensity earthquake scenario (scenario event - a damaging earthquake with higher probability of occurrence) for the city of Sofia

    NASA Astrophysics Data System (ADS)

    Aleksandrova, Irena; Simeonova, Stela; Solakov, Dimcho; Popova, Maria

    2014-05-01

    Among the many kinds of natural and man-made disasters, earthquakes dominate with regard to their social and economical impact on the urban environment. Global seismic risk to earthquakes are increasing steadily as urbanization and development occupy more areas that a prone to effects of strong earthquakes. Additionally, the uncontrolled growth of mega cities in highly seismic areas around the world is often associated with the construction of seismically unsafe buildings and infrastructures, and undertaken with an insufficient knowledge of the regional seismicity peculiarities and seismic hazard. The assessment of seismic hazard and generation of earthquake scenarios is the first link in the prevention chain and the first step in the evaluation of the seismic risk. The earthquake scenarios are intended as a basic input for developing detailed earthquake damage scenarios for the cities and can be used in earthquake-safe town and infrastructure planning. The city of Sofia is the capital of Bulgaria. It is situated in the centre of the Sofia area that is the most populated (the population is of more than 1.2 mil. inhabitants), industrial and cultural region of Bulgaria that faces considerable earthquake risk. The available historical documents prove the occurrence of destructive earthquakes during the 15th-18th centuries in the Sofia zone. In 19th century the city of Sofia has experienced two strong earthquakes: the 1818 earthquake with epicentral intensity I0=8-9 MSK and the 1858 earthquake with I0=9-10 MSK. During the 20th century the strongest event occurred in the vicinity of the city of Sofia is the 1917 earthquake with MS=5.3 (I0=7-8 MSK). Almost a century later (95 years) an earthquake of moment magnitude 5.6 (I0=7-8 MSK) hit the city of Sofia, on May 22nd, 2012. In the present study as a deterministic scenario event is considered a damaging earthquake with higher probability of occurrence that could affect the city with intensity less than or equal to VIII. The usable and realistic ground motion maps for urban areas are generated: - either from the assumption of a "reference earthquake" - or directly, showing values of macroseimic intensity generated by a damaging, real earthquake. In the study, applying deterministic approach, earthquake scenario in macroseismic intensity ("model" earthquake scenario) for the city of Sofia is generated. The deterministic "model" intensity scenario based on assumption of a "reference earthquake" is compared with a scenario based on observed macroseimic effects caused by the damaging 2012 earthquake (MW5.6). The difference between observed (Io) and predicted (Ip) intensities values is analyzed.

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

    USGS Publications Warehouse

    Wheeler, Russell L.

    2014-01-01

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

  11. Earthquake forecasting and warning

    SciTech Connect

    Rikitake, T.

    1983-01-01

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

  12. Crustal earthquake triggering by modern great earthquakes on subduction zone thrusts

    NASA Astrophysics Data System (ADS)

    Gomberg, Joan; Sherrod, Brian

    2014-02-01

    Among the many questions raised by the recent abundance of great (M > 8.0) subduction thrust earthquakes is their potential to trigger damaging earthquakes on crustal faults within the overriding plate and beneath many of the world's densely populated urban centers. We take advantage of the coincident abundance of great earthquakes globally and instrumental observations since 1960 to assess this triggering potential by analyzing centroids and focal mechanisms from the centroid moment tensor catalog for events starting in 1976 and published reports about the M9.5 1960 Chile and M9.2 1964 Alaska earthquake sequences. We find clear increases in the rates of crustal earthquakes in the overriding plate within days following all subduction thrust earthquakes of M > 8.6, within about ±10° of the triggering event centroid latitude and longitude. This result is consistent with dynamic triggering of more distant increases of shallow seismicity rates at distances beyond ±10°, suggesting that dynamic triggering may be important within the near field too. Crustal earthquake rate increases may also follow smaller M > 7.5 subduction thrust events, but because activity typically occurs offshore in the immediately vicinity of the triggering rupture plane, it cannot be unambiguously attributed to sources within the overriding plate. These observations are easily explained in the context of existing earthquake scaling laws.

  13. Introduction to the special issue on the 2004 Parkfield earthquake and the Parkfield earthquake prediction experiment

    USGS Publications Warehouse

    Harris, R.A.; Arrowsmith, J.R.

    2006-01-01

    The 28 September 2004 M 6.0 Parkfield earthquake, a long-anticipated event on the San Andreas fault, is the world's best recorded earthquake to date, with state-of-the-art data obtained from geologic, geodetic, seismic, magnetic, and electrical field networks. This has allowed the preearthquake and postearthquake states of the San Andreas fault in this region to be analyzed in detail. Analyses of these data provide views into the San Andreas fault that show a complex geologic history, fault geometry, rheology, and response of the nearby region to the earthquake-induced ground movement. Although aspects of San Andreas fault zone behavior in the Parkfield region can be modeled simply over geological time frames, the Parkfield Earthquake Prediction Experiment and the 2004 Parkfield earthquake indicate that predicting the fine details of future earthquakes is still a challenge. Instead of a deterministic approach, forecasting future damaging behavior, such as that caused by strong ground motions, will likely continue to require probabilistic methods. However, the Parkfield Earthquake Prediction Experiment and the 2004 Parkfield earthquake have provided ample data to understand most of what did occur in 2004, culminating in significant scientific advances.

  14. Shallow moonquakes - How they compare with earthquakes

    NASA Technical Reports Server (NTRS)

    Nakamura, Y.

    1980-01-01

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

  15. Strong ground motion prediction using virtual earthquakes.

    PubMed

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

    2014-01-24

    Sedimentary basins increase the damaging effects of earthquakes by trapping and amplifying seismic waves. Simulations of seismic wave propagation in sedimentary basins capture this effect; however, there exists no method to validate these results for earthquakes that have not yet occurred. We present a new approach for ground motion prediction that uses the ambient seismic field. We apply our method to a suite of magnitude 7 scenario earthquakes on the southern San Andreas fault and compare our ground motion predictions with simulations. Both methods find strong amplification and coupling of source and structure effects, but they predict substantially different shaking patterns across the Los Angeles Basin. The virtual earthquake approach provides a new approach for predicting long-period strong ground motion. PMID:24458636

  16. Disturbances in equilibrium function after major earthquake

    PubMed Central

    Honma, Motoyasu; Endo, Nobutaka; Osada, Yoshihisa; Kim, Yoshiharu; Kuriyama, Kenichi

    2012-01-01

    Major earthquakes were followed by a large number of aftershocks and significant outbreaks of dizziness occurred over a large area. However it is unclear why major earthquake causes dizziness. We conducted an intergroup trial on equilibrium dysfunction and psychological states associated with equilibrium dysfunction in individuals exposed to repetitive aftershocks versus those who were rarely exposed. Greater equilibrium dysfunction was observed in the aftershock-exposed group under conditions without visual compensation. Equilibrium dysfunction in the aftershock-exposed group appears to have arisen from disturbance of the inner ear, as well as individual vulnerability to state anxiety enhanced by repetitive exposure to aftershocks. We indicate potential effects of autonomic stress on equilibrium function after major earthquake. Our findings may contribute to risk management of psychological and physical health after major earthquakes with aftershocks, and allow development of a new empirical approach to disaster care after such events. PMID:23087814

  17. Disturbances in equilibrium function after major earthquake

    NASA Astrophysics Data System (ADS)

    Honma, Motoyasu; Endo, Nobutaka; Osada, Yoshihisa; Kim, Yoshiharu; Kuriyama, Kenichi

    2012-10-01

    Major earthquakes were followed by a large number of aftershocks and significant outbreaks of dizziness occurred over a large area. However it is unclear why major earthquake causes dizziness. We conducted an intergroup trial on equilibrium dysfunction and psychological states associated with equilibrium dysfunction in individuals exposed to repetitive aftershocks versus those who were rarely exposed. Greater equilibrium dysfunction was observed in the aftershock-exposed group under conditions without visual compensation. Equilibrium dysfunction in the aftershock-exposed group appears to have arisen from disturbance of the inner ear, as well as individual vulnerability to state anxiety enhanced by repetitive exposure to aftershocks. We indicate potential effects of autonomic stress on equilibrium function after major earthquake. Our findings may contribute to risk management of psychological and physical health after major earthquakes with aftershocks, and allow development of a new empirical approach to disaster care after such events.

  18. Earthquake sources near Uturuncu Volcano

    NASA Astrophysics Data System (ADS)

    Keyson, L.; West, M. E.

    2013-12-01

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

  19. Forecasting the Next Great San Francisco Earthquake

    NASA Astrophysics Data System (ADS)

    Rundle, P.; Rundle, J. B.; Turcotte, D. L.; Donnellan, A.; Yakovlev, G.; Tiampo, K. F.

    2005-12-01

    The great San Francisco earthquake of 18 April 1906 and its subsequent fires killed more than 3,000 persons, and destroyed much of the city leaving 225,000 out of 400,000 inhabitants homeless. The 1906 earthquake occurred on a km segment of the San Andreas fault that runs from the San Juan Bautista north to Cape Mendocino and is estimated to have had a moment magnitude m ,l 7.9. Observations of surface displacements across the fault were in the range m. As we approach the 100 year anniversary of this event, a critical concern is the hazard posed by another such earthquake. In this talk we examine the assumptions presently used to compute the probability of occurrence of these earthquakes. We also present the results of a numerical simulation of interacting faults on the San Andreas system. Called Virtual California, this simulation can be used to compute the times, locations and magnitudes of simulated earthquakes on the San Andreas fault in the vicinity of San Francisco. Of particular importance are new results for the statistical distribution of interval times between great earthquakes, results that are difficult or impossible to obtain from a purely field-based approach. We find that our results are fit well under most circumstances by the Weibull statistical distribution, and we compute waiting times to future earthquakes based upon our simulation results. A contrasting approach to the same problem has been adopted by the Working Group on California Earthquake Probabilities, who use observational data combined with statistical assumptions to compute probabilities of future earthquakes.

  20. Source parameters of Ulsan, Korea offshore earthquake sequence in 2012

    NASA Astrophysics Data System (ADS)

    Park, Eun Hee; Park, Sun-Cheon; Jeon, Young Soo; Hwang, Eui-Hong; Lee, Chang Wook; Choi, Young-Jean

    2013-04-01

    Seismicity in Korea is known to be relatively low compared to China and Japan. But the seismicity seems to be relatively active historically, according to historical documents on earthquake. The magnitudes of historical earthquakes were estimated mostly to be about 4 - 6 and there were some events with magnitude over 6. Instrumental earthquakes recorded in 1978 - 2012 seem to be smaller than historical earthquakes, according to the report by the Korea Meteorological Administration (KMA). Their magnitudes are smaller than 4 in general. Although epicenters of instrumental earthquakes seem to be randomly distributed on the entire Korean Peninsula, Some earthquakes occur intensively in several specific areas in the East Sea and the easternregion of Jeju Island. Among these areas, we studied earthquake cluster zones in the East Sea. We installed portable seismographs (8 stations) in the eastern coast and ocean bottom seismometers (4 stations) in the East Sea to study micro-earthquake activity and geotectonics. Observation was carried out from October, 2011 to April, 2012. We detected about 60 micro-earthquakes occurred around the temporal stations during the observation period. Among the seismicity observed in the period, we analyzed 6 earthquakes sequentially occurred in the Ulsan offshore on February 19 - March 27, 2012. For analysis of Ulsan offshore earthquake sequence, we used various data sets, including permanent stations of KMA, temporary stations, and Broadband Seismograph Network (F-net) of the National Research Institute for Earth Science and Disaster Prevention (NIED). For the hypocenter determination, 1D velocity structure (Chang and Baag, 2006) and HYPOELLIPSE (Lahr, 1980) were used. The equation of Tsuboi (1954) was used for determination of magnitude. The epicenters of the earthquakes were distributed within 3 km and the focal depths were in the range of 13 - 17 km, meaning shallow events. Magnitudes were 2.0 - 3.2. The largest earthquake was M3.2 event occurred at 00:05 (UTC) on February 24, 2012. According to analysis of focal mechanism, this earthquake was oblique strike-slip fault event. Prior to the sequence, no earthquake occurred in this area, and the seismicity pattern of this sequence showed the characteristics of swarm behavior without obvious mainshock. To understand the characteristics of seismic acitivty in earthquake cluster zones in the East Sea, researches on swarm behavior may be needed.

  1. "Naturally occurring asbestos

    NASA Astrophysics Data System (ADS)

    Cagnard, F.; Lahondère, D.; Blein, O.; Lahfid, A.; Wille, G.

    2012-04-01

    The term asbestos refers to six silicate minerals from amphibole and serpentine groups. By definition, it consists in bundles of thin and flexible long fibers, with high-tensile strength, and chemical and heat resistance. In contrast to asbestos found within commercial products and mining, the specific term ''naturally occurring asbestos'' (NOA) refers to asbestiform minerals occurring within rocks or soils that can be released by human activities or weathering processes. The fact that the exposure to asbestos is related to lung pathologies is now widely demonstrated (e.g. asbestosis, mesothelioma and lung cancer). However, if health risks associated with exposure to NOA exist, they are not yet well documented. The crystallization of natural asbestos occurs in specific Mg-rich lithologies associated with peculiar structural and metamorphic conditions. By recognizing and combining such specific geologic criteria, the presence or the absence of asbestos in bedrock terrains can be reasonably predicted and maps of NOA hazard can be drawn. We present here new results of geological mapping and petrological study concerning the evaluation of the NOA hazard in the Alps and Corsica, in France. The three folds approach consists in (1) a determination of lithologies with potential NOA from a bibliographic compilation and extraction of target zones from a geological geodatabase (2) a geological mapping of the target zones followed by a petrological characterization of sampled asbestiform minerals in the laboratory (optical microscopy, TEM, SEM, and Raman spectroscopy technics), and (3) the drawing of the final map of NOA hazard, at regional-scale. Occurrence criteria can be retained as follows: 1. NOA are abundant in the internal zones of the Alps and Corsica, especially within ophiolitic complexes. Natural asbestos are mostly concentrated within ultramafic rocks but can also occur within basic lithologies such as Mg-metagabbros, metabasalts and meta-pillow-lavas, 2. Asbestos is commonly located within fractures, shear-bands or shear-planes, developed during late retrograde metamorphic history, 3. Tremolite-actinolite-type asbestos is abundant both in ultramafic and mafic rocks, 4. Natural asbestos occur in few places within the external zones of the Alps, especially within hercynian ophiolitic massifs or concentrated in late Alpine fractures affecting leptyno-amphibolic lithologies.

  2. Computer simulation of earthquakes

    NASA Technical Reports Server (NTRS)

    Cohen, S. C.

    1976-01-01

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

  3. Earthquake precursors: activation or quiescence?

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  4. The persistence of directivity in small earthquakes

    USGS Publications Warehouse

    Boatwright, J.

    2007-01-01

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

  5. The Likelihood of Major Global Earthquakes and the 2014 Napa Earthquake

    NASA Astrophysics Data System (ADS)

    Ejeta, M. Z.

    2014-12-01

    A previous study that analyzed global major earthquakes of magnitude 7.6 and above for the 1897 to 1977 period suggests that random occurrence of these earthquakes is very unlikely (Olsson 1982). Following an analysis of global major earthquakes of magnitude 7 and above for the 1901 to January 2010 period, a recent study attempts to show an association between major global earthquake and cyclic lunisolar alignment events (Ejeta 2011). The latter study suggests that the inverse square relationship in Newton's law of universal gravitation is likely to explain the physics behind the skewed occurrences of major earthquake events around these alignment events. Using random and non-random occurrence analysis, this paper will present the likelihoods of major global earthquakes since 1990 through September 2014 and how the magnitude 6.0 Napa earthquake of 2014 may be a particular realization of the observed association. Specifically, it will show that using the random occurrence approach, the average probability of occurrence on any day of the 396 major earthquakes recorded by the United States Geological Survey (USGS) during the selected period, which has 9,039 days, is about 4.4%. It will also show that based on the observed association, these events are skewed, with average probabilities of about 39% and 68%, respectively, towards one and two days within lunisolar alignment events recorded by the National Aeronautic and Space Administration (NASA) during the same period. Of the 396 major earthquake events during the selected period, 154 and 271 occurred, respectively, within one and two days of either new, first quarter, full, or last quarter moon days. This result suggests that a major earthquake event that occurred during this period was more likely than not to have occurred within two days of an alignment event. The magnitude 6.0 Napa earthquake of August 24, 2014, occurred within a day of the August 25, 2014, new moon day. This paper suggests that further research and insight is likely to increase this skewed probability and calls for a continued research into the likelihood of earthquakes and their global spatial distributions around known tectonic plates. It also poses the question of the impact that better awareness about this likelihood may have on the normal functioning of the built environment.

  6. Earthquake recurrence in the central Himalaya: Some outstanding issues

    NASA Astrophysics Data System (ADS)

    Chittenipattu, Rajendran; Rajendran, Kusala; John, Biju; Sanwal, Jaishri

    2013-04-01

    Evaluation of the historic and geologic data from the central Himalaya suggests that the region experienced many significant earthquakes in the past. However, many questions remain on the pattern of earthquake recurrence, style of deformation and causative structures. A major question is when the last great earthquake in the central Himalaya was. While the renewal time of earthquakes originating on the detachment fault might match the expectations of the seismic gap models, the subsidiary faults within the wedge may localize strain leading to earthquakes events that need not maintain any temporal relation with the plate boundary breaking earthquakes and leading to surface slip due to the favorable geometry of the ramps. Observed temporal and spatial clustering of earthquakes along the Himalaya, nature of surface rupture and the amplified slip reported from geological section associated with the paleo-earthquakes may result from the dual nature of seismic sources along the Himalaya. This fundamental difference in source zones may be the key to understanding the temporal and spatial clustering of earthquakes along the Himalaya. The class of earthquakes that originate on the duplex zone propagate vertically on the steeply dipping faults and leading to surface ruptures, as observed in the 2005 Kashmir earthquake, that showed a peak surface offset of 7 m. Archaeo-seismological evidence point to a great earthquake in the central Himalaya occurred sometime between AD 1000 and AD 1290, suggesting a temporal gap of >800 years for great earthquakes in the region. Our studies also suggest that the source zone of the 1803 earthquake can be located close to Uttarkashi, on the duplex zone. The possible out-sequence-events like the 1803 Garhwal earthquake apparently suggest that the duplex zone south of the MCT is equally, if not more, active and capable of generating large/great earthquakes in the central Himalaya rather than the Himalayan frontal thrusts.. The age determinations of the paleoliquefaction features from the alluvial plain in Bihar and Uttar Pradesh suggest that previous great earthquakes in the respective segments may have occurred about 1000 years ago. These dates have some correlation with previous studies on the active faults on the Nepal side. We will present the results of our recent investigations of the geological proxies in the Himalaya and the Gangetic alluvial Plains along with a critical evaluation of the previous studies and discuss our strategy to address some of the outstanding questions on the earthquake recurrence in the central Himalaya.

  7. Earthquake Recurrence and Slip Over the Past 4 - 5 events on the Southern Santa Cruz Mountains Section of the San Andreas Fault

    NASA Astrophysics Data System (ADS)

    Streig, A. R.; Dawson, T. E.; Weldon, R. J.

    2011-12-01

    The Santa Cruz Mountains section (SAS) of the San Andreas fault last ruptured during the 1906 earthquake, an event that ruptured about 470 km, from Point Arena to San Juan Bautista, California. Paleoseismic studies on the SAS at the Grizzly Flat (GF) and Arano Flat - Mill Creek (AF) paleoseismic sites provide evidence of 1906 surface deformation, but have yielded differing records of prehistoric surface-fault ruptures. GF is located 14 km northwest of the AF site and records one 17th Century earthquake dated between 1632-1659 (Schwartz et al., 1996). The record at AF site records a younger penultimate earthquake between AD 1711 - 1770, with a third event between AD 1660-1670 (Fumal, in review). The AF sites suggest nine earthquakes in the past ~1000 years, and an average recurrence interval of 105 years over the past 1,000 years (Fumal et al., 2003). The Hazel Dell site is located approximately 9.5 km north of AF, between the AF and GF sites. This site has yielded good evidence of the most recent earthquake the 1906 surface rupture (E1), and 3 to 4 earlier events, including new evidence for two mid 1800's earthquakes. Evidence for the penultimate event, E2, is expressed as upward fault terminations within a massive sand infilling a topographic low. This sand infilled a depression formed by the pre-penultimate earthquake, E3. We identified milled wood stratigraphically below the pre-penultimate earthquake horizon, which suggests that surface rupturing earthquakes E2 and E3 occurred after deposition of the milled wood stratigraphic unit. Lumber harvesting began in the area around 1832, which suggests that earthquakes E2 and E3 are historical. Based on the presence of milled wood, the stratigraphic record at Hazel Dell appears more complete during the early historical period than at the AF and GF sites. These new event data for the SAS suggest more frequent surface rupturing earthquakes within historical time than previously recognized. We present a preliminary short-term slip rate estimate from a buried gravel offset 18 m where it crosses the fault. A charcoal sample collected from the gravel yielded a modeled age of 718 to 973 AD ± 2σ. We estimate a maximum short term slip rate of 17 mm/yr, which agrees with the slip rate determined north on the Peninsula section of the San Andreas fault (Hall and others, 1999). If all data in this study are correct, the SAS may be characterized by a multi-modal behavior in how strain is released through time. One mode of strain release, is through large multi-segment earthquakes, with moderate magnitude earthquakes occurring in the period between. The 1906 earthquake was a large multi-segment earthquake that dominates the moment budget of the fault. During the period prior to 1906, analysis of the historic record suggests that the SAS was characterized by a second mode, characterized by moderate seismicity, with six M≥ 6 earthquakes between 1840 and 1899 (Toppozada and others, 2002), all located along the southern half of the segment near the Hazel Dell study area. The two mid 1800's earthquakes identified in this study at Hazel Dell support this second mode of moderate seismicity on the SAS.

  8. Iceberg capsize hydrodynamics and the source of glacial earthquakes

    NASA Astrophysics Data System (ADS)

    Kaluzienski, Lynn; Burton, Justin; Cathles, Mac

    2014-03-01

    Accelerated warming in the past few decades has led to an increase in dramatic, singular mass loss events from the Greenland and Antarctic ice sheets, such as the catastrophic collapse of ice shelves on the western antarctic peninsula, and the calving and subsequent capsize of cubic-kilometer scale icebergs in Greenland's outlet glaciers. The latter has been identified as the source of long-period seismic events classified as glacial earthquakes, which occur most frequently in Greenland's summer months. The ability to partially monitor polar mass loss through the Global Seismographic Network is quite attractive, yet this goal necessitates an accurate model of a source mechanism for glacial earthquakes. In addition, the detailed relationship between iceberg mass, geometry, and the measured seismic signal is complicated by inherent difficulties in collecting field data from remote, ice-choked fjords. To address this, we use a laboratory scale model to measure aspects of the post-fracture calving process not observable in nature. Our results show that the combination of mechanical contact forces and hydrodynamic pressure forces generated by the capsize of an iceberg adjacent to a glacier's terminus produces a dipolar strain which is reminiscent of a single couple seismic source.

  9. The Algerian earthquake of October 10, 1980 - a preliminary report.

    USGS Publications Warehouse

    Espinosa, A.F.

    1981-01-01

    The earthquake occurred at 1.25 pm local time and had a surface-wave magnitude of 7.3. The main event was followed by an aftershock 3 hours later with a magnitude of 6.0. The main earthquake epicenter was located 170 km from the capital, Algiers. -from Author

  10. Frequently Asked Questions about Bunion Surgery

    MedlinePlus

    ... Size Print Bookmark Frequently Asked Questions About Bunion Surgery Here are some frequently asked questions (FAQs) and ... best for you. 5. How can I avoid surgery? Sometimes observation of the bunion is all that's ...

  11. Controls of the Xiannvshan Fault on landslides and Reservoir induced earthquakes located at head area of the Three Gorges Reservoir

    NASA Astrophysics Data System (ADS)

    Shimei, Wang; Yeming, Zhang

    2015-04-01

    Landslides and reservoir induced earthquakes are two main types of geological disasters, which have serious influence on the Three Gorges Project. The Xiannvshan Fault is ten kilometers away from the Three Gorges Dam, and it has important control on landslides and earthquakes located at head area of the Three Gorges Reservoir. Data collected show that: (1) the fault stretch runs in northwest-west orientation with a total length of more than 80 kilometers, it north endpoint extends to the Yangtze River and Jiuwanxi Fault is one of its branches. The Xiannvshan Fault has a high level of activity with the average annual decline of 0.076mm in the west wall and the dextral sliding of 0.116mm. (2) Controls on landslides resulted from the Xiannvshan Fault lie in two aspects. One is a large of landslide accumulation bodies resulted from two collapse events, which are corresponded to the two intense faulting. The other is that the Xintan landslide occurred in 1982, which is resulted from the stress accumulation of the fault. (3) The Xiannvshan Fault is active. Three big earthquakes had been induced by the fault from 1959 to the time of impounding, of which one occurred at its southern endpoint, Panjiawan of Yidu, and was magnitude 5, one occurred at its northern section, Zhou Ping, and was magnitude 3.3, and another occurred at Huilongguan of Zigui with a magnitude 5.1. Earthquakes have been happening more frequently after the impoundment of the Three Gorges Reservoir or on the high water level than before. More than 40 earthquakes with magnitudes bigger than 3.3 were recorded after the impoundment, of which 4 ranged from 4.1 to 5.1 and occurred when the high water level was decreasing. Otherwise, most earthquakes centered on the northern endpoint of the fault, which indicates a characteristics of tectonic reservoir earthquake. This study, for the three gorges reservoir area landslide and seismic reservoir prediction is of great significance.

  12. Prediction of Future Great Earthquake Locations from Cumulative Stresses Released by Prior Earthquakes

    NASA Astrophysics Data System (ADS)

    Lee, J.; Hong, T. K.

    2014-12-01

    There are 17 great earthquakes with magnitude greater than or equal to 8.5 in the world since 1900. The great events cause significant damages to the humanity. The prediction of potential maximum magnitudes of earthquakes is important for seismic hazard mitigation. In this study, we calculate the Coulomb stress changes around the active plate margins for 507 events with magnitudes greater than 7.0 during 1976-2013 to estimate the cumulative stress releases. We investigate the spatio-temporal variations of ambient stress field from the cumulative Coulomb stress changes as a function of plate motion speed, plate age and dipping angle. It is observed that the largest stress drop occur in relatively high plate velocity in the convergent margins between Nazca and South American plates, between Pacific and North American plates, between Philippine Sea and Eurasian plates, and between Pacific and Australian plates. It is intriguing to note that the great earthquakes such as Tohoku-Oki earthquake and Maule earthquake occur in the highest plate velocity. On the other hand, the largest stress drop occur in the margins with relatively slow plate speeds such as the boundaries between Cocos and North American plates and between Indo-Australian and Eurasian plates. Earthquakes occur dominantly in the regions with positive Coulomb stress changes, suggesting that post-earthquakes are controlled by the stresses released from prior earthquakes. We find strong positive correlations between Coulomb stress changes and plate speeds. The observation suggests that large stress drop was controlled by high plate speed, suggesting possible prediction of potential maximum magnitudes of events.

  13. Fractal Dimension of Earthquakes From Relocated Seismicity

    NASA Astrophysics Data System (ADS)

    Nadaeau, R. M.

    2001-12-01

    Fractal dimension (D) describing the distribution of earthquakes has been shown to be a very useful parameter for understanding earthquakes on many levels. Estimates of D have been used to infer the state of stress in Earth's crust, the degree of predictability of earthquakes, scaling relationships for earthquake source parameters recurrence times and b-values, and for estimating kernels used in earthquake hazard estimation. Most estimates of D (D2 and Do) for earthquake distributions are based on earthquake epicentral (2-D) or hypocenters (3-D) locations from standard location catalogs derived using routine location methods. Location uncertainties using these methods are typically on the order of 1 km or more in both relative terms. Relative uncertainties can be viewed as the scatter of earthquakes from their true locations, and in 2 and 3 dimensions this property preferentially increases separation distances (offsets) between events. This imposes serious limitations on the accuracy with which D can be determined, since it limits the usable range of event separations and introduces a bias in D estimates towards larger values by diminishing the numbers of small offsets in favor of larger offsets. Location uncertainties can also mask second order effects in fractal structure such as log-periodic fluctuations indicative of discrete rescaling, hierarchal clustering, and lineations in earthquake quake distributions. In this study, various catalogs of relocated events derived using cross-correlation and double-difference techniques on earthquakes occurring along the SAF system in Central CA are used to estimate D (3-D) and the estimates are compared with those derived using corresponding routine catalogs and relocated catalogs with random scatter added. Implications of the results are discussed. Initial results indicate that D using relocated events is generally between 1 and 1.5, compared to 2 or greater using routine catalogs and relocated catalogs with 1 km of added scatter. The effect of masking second order fractal structure is also observed. The lower values of D suggest a lower stress criticality in Earth's crust in this region and greater predictability of earthquake occurrence. Lower D is also in accordance with scaling relationships derived using repeating earthquakes from this region.

  14. Implications for prediction and hazard assessment from the 2004 Parkfield earthquake.

    PubMed

    Bakun, W H; Aagaard, B; Dost, B; Ellsworth, W L; Hardebeck, J L; Harris, R A; Ji, C; Johnston, M J S; Langbein, J; Lienkaemper, J J; Michael, A J; Murray, J R; Nadeau, R M; Reasenberg, P A; Reichle, M S; Roeloffs, E A; Shakal, A; Simpson, R W; Waldhauser, F

    2005-10-13

    Obtaining high-quality measurements close to a large earthquake is not easy: one has to be in the right place at the right time with the right instruments. Such a convergence happened, for the first time, when the 28 September 2004 Parkfield, California, earthquake occurred on the San Andreas fault in the middle of a dense network of instruments designed to record it. The resulting data reveal aspects of the earthquake process never before seen. Here we show what these data, when combined with data from earlier Parkfield earthquakes, tell us about earthquake physics and earthquake prediction. The 2004 Parkfield earthquake, with its lack of obvious precursors, demonstrates that reliable short-term earthquake prediction still is not achievable. To reduce the societal impact of earthquakes now, we should focus on developing the next generation of models that can provide better predictions of the strength and location of damaging ground shaking. PMID:16222291

  15. Psychological Intervention in Primary Care After Earthquakes in Lorca, Spain

    PubMed Central

    Garriga, Ascensión; Egea, Carmen

    2015-01-01

    Objective: After the earthquakes that occurred in Lorca, Spain, on May 11, 2011, the regional mental health management employed 2 clinical psychologists for 6 months to provide care to people referred by primary care physicians. The objective was to address the expected increased demand for treatment of mental disorders, notably posttraumatic stress disorder (PTSD) and adjustment disorders. Method: Referred individuals were evaluated and treated according to a clinical protocol designed ad hoc from June 12, 2011, to November 30, 2011. The protocol provided a stepped intervention guided by clinical and psychometric assessment using “normalization” for those with no psychiatric diagnosis, brief group treatment for mild to moderate PTSD or adjustment disorders, individual treatment for more severe PTSD, and referral to the local mental health center for other mental health disorders. Standard adult and child scales to assess posttraumatic, depression, and anxiety symptoms and resilience were used at initial assessment to guide treatment allocation and repeated to assess outcome status. Psychologists also provided a clinical assessment of symptom resolution at the end of the study. Results: Rates of symptom resolution and improvements on all scales (PTSD, depression, anxiety, and resilience) demonstrated clinically and statistically significant improvement in all treatment groups (P = .000). Dropout was low. Medications were prescribed frequently to adults; no child received medication as a result of the earthquakes. No case of mental disorder related to the earthquakes was referred to the local mental health center during the 6 months of psychologist intervention. Conclusion:The structured intervention resulted in a high resolution of cases and low dropout, allowing treatment of a larger number of people with optimal frequency (weekly), devoting more time to the most severe cases and less to those moderately or mildly affected. PMID:26137356

  16. Naturally occuring mutagens.

    PubMed

    Clark, A M

    1976-01-01

    Naturally occurring mutagens have usually been discovered as a result of outbreaks of disease in agricultural livestock, or as a result of epidemiological studies of cancer of the liver in man. Subsequent work has then shown that the toxic agents responsible often have mutagenic properties. Examples are the pyrrolizidine alkaloids, cyasin, a range of mycotoxins produced by various fungi, and at least two unidentified toxic agents in bracken. Commonly the toxic agent itself does not show high biological activity, but after ingestion it is converted by metabolic processes into the active mutagen or carcinogen. Some of these toxic substances have been responsible for considerable losses of agricultural livestock and therefore are of economic significance. From the view-point of genetic hazards to man, the most significant compounds are probably the mycotoxins, e.g. aflatoxin, because of the common risk of fungal contamination of food, especially in tropical regions. No information is yet available on the effects of these mutagens on natural populations of animals. Plants containing the pyrrolizidine alkaloids are found in areas of Africa and the Middle East where plagues of the migratory locust occur. Although it is known that some of the alkaloids can induce chromosomal damage in grasshoppers, whether such damage ever becomes a significant factor under ecological conditions is not known. In some cases, insects have not only evolved resistance towards mutagenic alkaloids but have become dependent on them for certain purposes. The males of certain Danaid butterflies feed on plants containing pyrrolizidine alkaloids. After ingestion, the alkaloids are metabolised to dihydropyrrolizine derivatives, which are then secreted on special organs (hair pencils) and, following dissemination into the atmosphere, act as pheromones for the stimulation of mating behaviour. PMID:958226

  17. Earthquake at 40 feet

    USGS Publications Warehouse

    Miller, G. J.

    1976-01-01

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

  18. NCEER seminars on earthquakes

    USGS Publications Warehouse

    Pantelic, J.

    1987-01-01

    In May of 1986, the National Center for Earthquake Engineering Research (NCEER) in Buffalo, New York, held the first seminar in its new monthly forum called Seminars on Earthquakes. The Center's purpose in initiating the seminars was to educate the audience about earthquakes, to facilitate cooperation between the NCEER and visiting researchers, and to enable visiting speakers to learn more about the NCEER   

  19. Source parameters of a M4.8 and its accompanying repeating earthquakes off Kamaishi, NE Japan: Implications for the hierarchical structure of asperities and earthquake cycle

    USGS Publications Warehouse

    Uchida, N.; Matsuzawa, T.; Ellsworth, W.L.; Imanishi, K.; Okada, T.; Hasegawa, A.

    2007-01-01

    We determine the source parameters of a M4.9 ?? 0.1 'characteristic earthquake' sequence and its accompanying microearthquakes at ???50 km depth on the subduction plate boundary offshore of Kamaishi, NE Japan. The microearthquakes tend to occur more frequently in the latter half of the recurrence intervals of the M4.9 ?? 0.1 events. Our results show that the microearthquakes are repeating events and they are located not only around but also within the slip area for the 2001 M4.8 event. From the hierarchical structure of slip areas and smaller stress drops for the microearthquakes compared to the M4.8 event, we infer the small repeating earthquakes rupture relatively weak patches in and around the slip area for the M4.8 event and their activity reflects a stress concentration process and/or change in frictional property (healing) at the area. We also infer the patches for the M4.9 ?? 0.1 and other repeating earthquakes undergo aseismic slip during their interseismic period. Copyright 2007 by the American Geophysical Union.

  20. Absence of remotely triggered large earthquakes beyond the mainshock region

    USGS Publications Warehouse

    Parsons, T.; Velasco, A.A.

    2011-01-01

    Large earthquakes are known to trigger earthquakes elsewhere. Damaging large aftershocks occur close to the mainshock and microearthquakes are triggered by passing seismic waves at significant distances from the mainshock. It is unclear, however, whether bigger, more damaging earthquakes are routinely triggered at distances far from the mainshock, heightening the global seismic hazard after every large earthquake. Here we assemble a catalogue of all possible earthquakes greater than M 5 that might have been triggered by every M 7 or larger mainshock during the past 30 years. We compare the timing of earthquakes greater than M 5 with the temporal and spatial passage of surface waves generated by large earthquakes using a complete worldwide catalogue. Whereas small earthquakes are triggered immediately during the passage of surface waves at all spatial ranges, we find no significant temporal association between surface-wave arrivals and larger earthquakes. We observe a significant increase in the rate of seismic activity at distances confined to within two to three rupture lengths of the mainshock. Thus, we conclude that the regional hazard of larger earthquakes is increased after a mainshock, but the global hazard is not.

  1. The 2005 Tarapaca earthquake: a likely indirect trigger of the 2014 Iquique earthquake

    NASA Astrophysics Data System (ADS)

    Bie, Lidong; Ryder, Isabelle

    2015-04-01

    Static stress change has been proposed as an integral earthquake triggering mechanism. Here we investigate the effect of 2005 Tarapaca earthquake on the occurrence of the 2014 M8.1 Iquique earthquake from the static stress change triggering perspective. The 2005 Mw7.8 Tarapaca earthquake occurred ~200 km to east of the Iquique earthquake and was identified as a result of normal faulting on a west-dipping plane at depths between 90 and 115 km within the subducting slab of northern Chile (Delouis and Legrand, 2007). It is supposed that the induced coseismic stress could be gradually released by any nearby weak layers. Before calculating the Coulomb stress changes associated with the coseismic slip and postseismic processes, we first need to constrain the subduction zone rheological properties. We built a postseismic deformation rate map for the Tarapaca earthquake using 45 atmospheric noise corrected interferograms. The Envisat-recorded short-term postseismic deformation shows a broad pattern of uplift across the fault's surface projection. A semi-analytical three-dimensional model considering the vertical and horizontal rheological heterogeneities was tested with variable inputs to obtain a set of optimal rheological parameters. With the optimal rheological parameters as input, we then compute the static Coulomb stress change on the megathrust interface caused by the coseismic slip and viscoelastic relaxation (VER) processes of the Tarapaca earthquake. It is found that the coseismic rupture and most aftershocks of the Iquique earthquake locate in a zone with negative stress loading. However, calculation of Coulomb stress change on nodal planes of the M6.7 preshock shows a positive loading on the shallow dipping fault plane, which indicates a likely triggering effect on the preshock. Based on the understanding that the preshock triggered the mainshock, we suggest that the 2005 Tarapaca earthquake may act as an indirect trigger of the 2014 Iquique earthquake.

  2. On the reported magnetic precursor of the 1989 Loma Prieta earthquake

    USGS Publications Warehouse

    Thomas, J.N.; Love, J.J.; Johnston, M.J.S.

    2009-01-01

    Among the most frequently cited reports in the science of earthquake prediction is that by Fraser-Smith et al. (1990) and Bernardi et al. (1991). They found anomalous enhancement of magnetic-field noise levels prior to the 18 October 1989 Loma Prieta earthquake in the ultra-low-frequency range (0.0110-10.001 Hz) from a ground-based sensor at Corralitos, CA, just 7 km from the earthquake epicenter. In this analysis, we re-examine all of the available Corralitos data (21 months from January 1989 to October 1990) and the logbook kept during this extended operational period. We also examine 1.0-Hz (1-s) data collected from Japan, 0.0167-Hz (1-min) data collected from the Fresno, CA magnetic observatory, and the global Kp magnetic-activity index. The Japanese data are of particular importance since their acquisition rate is sufficient to allow direct comparison with the lower-frequency bands of the Corralitos data. We identify numerous problems in the Corralitos data, evident from both straightforward examination of the Corralitos data on their own and by comparison with the Japanese and Fresno data sets. The most notable problems are changes in the baseline noise levels occurring during both the reported precursory period and at other times long before and after the earthquake. We conclude that the reported anomalous magnetic noise identified by Fraser-Smith et al. and Bernardi et al. is not related to the Loma Prieta earthquake but is an artifact of sensor-system malfunction. ?? 2008 Elsevier B.V.

  3. Earthquakes, active faults, and geothermal areas in the imperial valley, california.

    PubMed

    Hill, D P; Mowinckel, P; Peake, L G

    1975-06-27

    A dense seismograph network in the Imperial Valley recorded a series of earthquake swarms along the Imperial and Brawley faults and a diffuse pattern of earthquakes along the San Jacinto fault. Two known geothermal areas are closely associated with these earthquake swarms. This seismicity pattern demonstrates that seismic slip is occurring along both the Imperial-Brawley and San Jacinto fault systems. PMID:17772600

  4. Earthquakes clustering based on the magnitude and the depths in Molluca Province

    NASA Astrophysics Data System (ADS)

    Wattimanela, H. J.; Pasaribu, U. S.; Indratno, S. W.; Puspito, A. N. T.

    2015-12-01

    In this paper, we present a model to classify the earthquakes occurred in Molluca Province. We use K-Means clustering method to classify the earthquake based on the magnitude and the depth of the earthquake. The result can be used for disaster mitigation and for designing evacuation route in Molluca Province.

  5. Earthquake nucleation by transient deformations caused by the M = 7.9 Denali, Alaska, earthquake

    NASA Astrophysics Data System (ADS)

    Gomberg, J.; Bodin, P.; Larson, K.; Dragert, H.

    2004-02-01

    The permanent and dynamic (transient) stress changes inferred to trigger earthquakes are usually orders of magnitude smaller than the stresses relaxed by the earthquakes themselves, implying that triggering occurs on critically stressed faults. Triggered seismicity rate increases may therefore be most likely to occur in areas where loading rates are highest and elevated pore pressures, perhaps facilitated by high-temperature fluids, reduce frictional stresses and promote failure. Here we show that the 2002 magnitude M = 7.9 Denali, Alaska, earthquake triggered widespread seismicity rate increases throughout British Columbia and into the western United States. Dynamic triggering by seismic waves should be enhanced in directions where rupture directivity focuses radiated energy, and we verify this using seismic and new high-sample GPS recordings of the Denali mainshock. These observations are comparable in scale only to the triggering caused by the 1992 M = 7.4 Landers, California, earthquake, and demonstrate that Landers triggering did not reflect some peculiarity of the region or the earthquake. However, the rate increases triggered by the Denali earthquake occurred in areas not obviously tectonically active, implying that even in areas of low ambient stressing rates, faults may still be critically stressed and that dynamic triggering may be ubiquitous and unpredictable.

  6. Earthquake nucleation by transient deformations caused by the M = 7.9 Denali, Alaska, earthquake

    USGS Publications Warehouse

    Gomberg, J.; Bodin, P.; Larson, K.; Dragert, H.

    2004-01-01

    The permanent and dynamic (transient) stress changes inferred to trigger earthquakes are usually orders of magnitude smaller than the stresses relaxed by the earthquakes themselves, implying that triggering occurs on critically stressed faults. Triggered seismicity rate increases may therefore be most likely to occur in areas where loading rates are highest and elevated pore pressures, perhaps facilitated by high-temperature fluids, reduce frictional stresses and promote failure. Here we show that the 2002 magnitude M = 7.9 Denali, Alaska, earthquake triggered wide-spread seismicity rate increases throughout British Columbia and into the western United States. Dynamic triggering by seismic waves should be enhanced in directions where rupture directivity focuses radiated energy, and we verify this using seismic and new high-sample GPS recordings of the Denali mainshock. These observations are comparable in scale only to the triggering caused by the 1992 M = 7.4 Landers, California, earthquake, and demonstrate that Landers triggering did not reflect some peculiarity of the region or the earthquake. However, the rate increases triggered by the Denali earthquake occurred in areas not obviously tectonically active, implying that even in areas of low ambient stressing rates, faults may still be critically stressed and that dynamic triggering may be ubiquitous and unpredictable.

  7. Integrated Simulation of Earthquake Generation and Ground Motion and Tsunami for Nankai Trough Megathrust Earthquakes

    NASA Astrophysics Data System (ADS)

    Todoriki, M.; Hyodo, M.; Hori, T.; Furumura, T.; Maeda, T.

    2014-12-01

    We have conducted an integrated simulation of earthquake generation and seismic ground motion and tsunami for realizing a realistic earthquake scenario for large earthquakes along the Nankai Trough in southwest Japan where large earthquakes have repeatedly occurred with the recurrence interval of 100-150 years. The understanding of diversity of the characteristics of the huge earthquakes and their seismic and tsunami hazards are quite important issue. Various earthquake cycle simulations have been recently performed to estimate the diversity of the patterns of the huge earthquakes in the trough and the possibility of the future earthquakes, where the fault rupture propagation process and the friction in a plate boundary are considered. Here, we integrated these two simulations by one-way weakly coupled approach; First we conduct the quasi-dynamic earthquake cycle simulation, then the resultant time-dependent heterogeneous slip histories on the plate boundary are smoothly connected to as inputs of the ground motion and tsunami simulation. As a trial of this approach, the integrated simulation was performed under the huge earthquake scenario with large fault rupture area very similar to the 1707 Hoei earthquake. The target volume of the latter simulation is 1,200 km (EW) x 1,000 km (NS) x 250 km (depth). The equations of motion for viscoelastic body were solved by finite-difference method with discretization of 0.5 km and 0.25 km in horizontal and vertical direction, respectively. For such large-scale simulation the K computer at the AICS, RIKEN was utilized with 2,400 CPUs. The computation time was approx. 1 hour for 80,000 time steps calculation. The results of the integrated simulation show that we successfully reproduced a series of phenomena from earthquake generation to seismic wave propagation, strong ground motion in land, and tsunami growth. Moreover, we confirmed seismic wave generation accompanied by the heterogeneous fault rupture propagation on the plate boundary and the features of the subsequent ground motion on earth surface. It is expected that the high-performance computing of the integrated system enables us to investigate diversity of the seismic and tsunami hazards of huge earthquakes in southwestern Japan as well as their complexity of earthquake generation itself based on physical models.

  8. Activated Very Low Frequency Earthquakes By the Slow Slip Events in the Ryukyu Subduction Zone

    NASA Astrophysics Data System (ADS)

    Nakamura, M.; Sunagawa, N.

    2014-12-01

    The Ryukyu Trench (RT), where the Philippine Sea plate is subducting, has had no known thrust earthquakes with a Mw>8.0 in the last 300 years. However, the rupture source of the 1771 tsunami has been proposed as an Mw > 8.0 earthquake in the south RT. Based on the dating of tsunami boulders, it has been estimated that large tsunamis occur at intervals of 150-400 years in the south Ryukyu arc (RA) (Araoka et al., 2013), although they have not occurred for several thousand years in the central and northern Ryukyu areas (Goto et al., 2014). To address the discrepancy between recent low moment releases by earthquakes and occurrence of paleo-tsunamis in the RT, we focus on the long-term activity of the very low frequency earthquakes (VLFEs), which are good indicators of the stress release in the shallow plate interface. VLFEs have been detected along the RT (Ando et al., 2012), which occur on the plate interface or at the accretionary prism. We used broadband data from the F-net of NIED along the RT and from the IRIS network. We applied two filters to all the raw broadband seismograms: a 0.02-0.05 Hz band-pass filter and a 1 Hz high-pass filter. After identification of the low-frequency events from the band-pass-filtered seismograms, the local and teleseismic events were removed. Then we picked the arrival time of the maximum amplitude of the surface wave of the VLFEs and determined the epicenters. VLFEs occurred on the RA side within 100 km from the trench axis along the RT. Distribution of the 6670 VLFEs from 2002 to 2013 could be divided to several clusters. Principal large clusters were located at 27.1-29.0N, 25.5-26.6N, and 122.1-122.4E (YA). We found that the VLFEs of the YA are modulated by repeating slow slip events (SSEs) which occur beneath south RA. The activity of the VLFEs increased to two times of its ordinary rate in 15 days after the onset of the SSEs. Activation of the VLFEs could be generated by low stress change of 0.02-20 kPa increase in Coulomb failure stress. The strain in the plate interface where the VLFEs occur frequently would be released by small change in stress. Cluster of the VLFEs is complementally to the historical tsunami source area and locked area. Continuous activity of VLFEs would release the stress patchily in the plate interface and give the constraint to the maximum size of large thrust earthquakes.

  9. Slow earthquake in Afghanistan detected by InSAR

    NASA Astrophysics Data System (ADS)

    Furuya, M.; Satyabala, S. P.

    2008-03-01

    The Chaman fault system forms a prominent ~900-km-long left-lateral transform plate boundary between the Indian and Eurasian plates in Afghanistan and Pakistan. Here we show satellite radar interferometry data that revealed an afterslip (or slow earthquake) signal following an earthquake of magnitude 5.0. This slow slip episode lasted for more than a year, and accompanied a widespread creep signal that occurred at least ~50 km along the fault. We detected no surface slip before the earthquake during the 1.5 years sampled by our data. This finding of long-lasting widespread afterslip demonstrates that the plate motion along the Chaman Fault is accommodated by slow slip episodes following moderate earthquakes, and suggests that a potential for magnitude 7-class earthquakes was significantly reduced. The duration and moment release of the detected afterslip do not fit the recently proposed scaling law for slow earthquakes.

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

    PubMed

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

    2014-01-01

    When an earthquake occurs, seismologists want to use recorded seismograms to infer its location, magnitude and source-focal mechanism as quickly as possible. If such information could be determined immediately, timely evacuations and emergency actions could be undertaken to mitigate earthquake damage. Current advanced methods can report the initial location and magnitude of an earthquake within a few seconds, but estimating the source-focal mechanism may require minutes to hours. Here we present an earthquake search engine, similar to a web search engine, that we developed by applying a computer fast search method to a large seismogram database to find waveforms that best fit the input data. Our method is several thousand times faster than an exact search. For an Mw 5.9 earthquake on 8 March 2012 in Xinjiang, China, the search engine can infer the earthquake's parameters in <1 s after receiving the long-period surface wave data. PMID:25472861

  11. Earthquake Hazard in the Heart of the Homeland

    USGS Publications Warehouse

    Gomberg, Joan; Schweig, Eugene

    2007-01-01

    Evidence that earthquakes threaten the Mississippi, Ohio, and Wabash River valleys of the Central United States abounds. In fact, several of the largest historical earthquakes to strike the continental United States occurred in the winter of 1811-1812 along the New Madrid seismic zone, which stretches from just west of Memphis, Tenn., into southern Illinois. Several times in the past century, moderate earthquakes have been widely felt in the Wabash Valley seismic zone along the southern border of Illinois and Indiana. Throughout the region, between 150 and 200 earthquakes are recorded annually by a network of monitoring instruments, although most are too small to be felt by people. Geologic evidence for prehistoric earthquakes throughout the region has been mounting since the late 1970s. But how significant is the threat? How likely are large earthquakes and, more importantly, what is the chance that the shaking they cause will be damaging?

  12. Are Earthquake Magnitudes Clustered?

    SciTech Connect

    Davidsen, Joern; Green, Adam

    2011-03-11

    The question of earthquake predictability is a long-standing and important challenge. Recent results [Phys. Rev. Lett. 98, 098501 (2007); ibid.100, 038501 (2008)] have suggested that earthquake magnitudes are clustered, thus indicating that they are not independent in contrast to what is typically assumed. Here, we present evidence that the observed magnitude correlations are to a large extent, if not entirely, an artifact due to the incompleteness of earthquake catalogs and the well-known modified Omori law. The latter leads to variations in the frequency-magnitude distribution if the distribution is constrained to those earthquakes that are close in space and time to the directly following event.

  13. Earthquake history of Oregon

    USGS Publications Warehouse

    von Hake, C. A.

    1976-01-01

    Although situated between two States (California and Washington) that have has many violent earthquakes, Oregon is noticeably less active seismically. the greatest damage experienced resulted from a major shock near Olympia, Wash., in 1949. During the short history record available (since 1841), 34 earthquakes of intensity V, Modified Mercalli Scale, or greater have centered within Oregon or near its borders. Only 13 of the earthquakes had an intensity above V, and many of the shocks were local. However, a 1936 earthquake in the eastern Oregon-Washington region caused extensive damage and was felt over an area of 272,000 square kilometers. 

  14. Earthquake Breccias (Invited)

    NASA Astrophysics Data System (ADS)

    Rowe, C. D.; Melosh, B. L.; Lamothe, K.; Schnitzer, V.; Bate, C.

    2013-12-01

    Fault breccias are one of the fundamental classes of fault rocks and are observed in many exhumed faults. Some breccias have long been assumed to form co-seismically, but textural or mechanistic evidence for the association with earthquakes has never been documented. For example, at dilational jogs in brittle faults, it is common to find small bodies of chaotic breccia in lenticular or rhombohedral voids bounded by main slip surfaces and linking segments. Sibson interpreted these 'implosion breccias' as evidence of wall rock fracturing during sudden unloading when the dilational jogs open during earthquake slip (Sibson 1985, PAGEOPH v. 124, n. 1, 159-175). However, the role of dynamic fracturing in forming these breccias has not been tested. Moreover, the criteria for identifying implosion breccia have not been defined - do all breccias in dilational jogs or step-overs represent earthquake slip? We are building a database of breccia and microbreccia textures to develop a strictly observational set of criteria for distinction of breccia texture classes. Here, we present observations from the right-lateral Pofadder Shear Zone, South Africa, and use our textural criteria to identify the relative roles of dynamic and quasi-static fracture patterns, comminution/grinding and attrition, hydrothermal alteration, dissolution, and cementation. Nearly 100% exposure in the hyper-arid region south of the Orange River allowed very detailed mapping of frictional fault traces associated with rupture events, containing one or more right-steps in each rupture trace. Fracture patterns characteristic of on- and off-fault damage associated with propagation of dynamic rupture are observed along straight segments of the faults. The wall rock fractures are regularly spaced, begin at the fault trace and propagate at a high angle to the fault, and locally branch into subsidiary fractures before terminating a few cm away. This pattern of fractures has been previously linked to dynamic fracture tip propagation in both field studies and analog experiments. In dilational jogs, these fractures interact and intersect the wall rock foliation to cut the wall rock into distinctive clast shapes and sizes, giving the breccia a characteristic texture that can be defined quantitatively by image analysis. Breccia clast morphology, size distribution and angularity are markers for dynamic fracture patterns. Older microbreccias are cemented, and interfingering grain boundaries between quartz in clasts and quartz in cement show that crystal plastic deformation of quartz has occurred after breccia cementation. These deformed breccias are cut by younger breccias, establishing cyclicity of brittle and ductile slip on the Pofadder Shear Zone. Our results distinguish between fault breccias that could have formed quasi-statically, and those that are the result of dynamic processes and therefore define a new tool for recognizing earthquakes in the rock record.

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

    USGS Publications Warehouse

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

    2012-01-01

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

  16. Landslides triggered by the earthquake

    SciTech Connect

    Harp, E.L.; Keefer, D.K.

    1990-01-01

    The May 2 earthquake triggered landslides numbering in the thousands. Most numerous were rockfalls and rockslides that occurred mainly on slopes steeper than 60{degree} within sandstone, siltstone, and shale units of Upper Cretaceous and Tertiary strata. Soil falls from cutbank slopes along streams were also numerous. Seven slumps in natural slopes were triggered, and minor liquefaction-induced lateral-spread failures occurred along Los Gatos Creek. Rockfalls and rockslides occurred as far as 34 km northwest, 15 km south, and 26 km southwest of the epicenter. There were few slope failures to the east of the epicenter, owing to the absence of steep slopes in that direction. Throughout the area affected, rockfalls and rockslides were concentrated on southwest-facing slopes; the failures on slopes facing in the southwest quadrant accounted for as much as 93% of all failures in some areas. Rockfalls and rockslides from ridge crests were predominantly from sandstone units. Along steeply incised canyons, however, failures in shale and siltstone units were also common. Small rockslides and soil slides occurred from cut slopes above oil-well pump pads in the oil fields; slumps were common in the outer parts of steep fill slopes of the pump pads. The distribution of seismically induced landslides throughout the entire earthquake-affected area was mapped from true-color airphotos taken on May 3, 1985.

  17. Naturally Occurring Food Toxins

    PubMed Central

    Dolan, Laurie C.; Matulka, Ray A.; Burdock, George A.

    2010-01-01

    Although many foods contain toxins as a naturally-occurring constituent or, are formed as the result of handling or processing, the incidence of adverse reactions to food is relatively low. The low incidence of adverse effects is the result of some pragmatic solutions by the US Food and Drug Administration (FDA) and other regulatory agencies through the creative use of specifications, action levels, tolerances, warning labels and prohibitions. Manufacturers have also played a role by setting limits on certain substances and developing mitigation procedures for process-induced toxins. Regardless of measures taken by regulators and food producers to protect consumers from natural food toxins, consumption of small levels of these materials is unavoidable. Although the risk for toxicity due to consumption of food toxins is fairly low, there is always the possibility of toxicity due to contamination, overconsumption, allergy or an unpredictable idiosyncratic response. The purpose of this review is to provide a toxicological and regulatory overview of some of the toxins present in some commonly consumed foods, and where possible, discuss the steps that have been taken to reduce consumer exposure, many of which are possible because of the unique process of food regulation in the United States. PMID:22069686

  18. Naturally occurring cardiac glycosides.

    PubMed

    Radford, D J; Gillies, A D; Hinds, J A; Duffy, P

    1986-05-12

    Cardiac glycoside poisoning from the ingestion of plants, particularly of oleanders, occurs with reasonable frequency in tropical and subtropical areas. We have assessed a variety of plant specimens for their cardiac glycoside content by means of radioimmunoassays with antibodies that differ in their specificity for cardiac glycosides. Significant amounts of immunoreactive cardiac glycoside were found to be present in the ornamental shrubs: yellow oleander (Thevetia peruviana); oleander (Nerium oleander); wintersweet (Carissa spectabilis); bushman's poison (Carissa acokanthera); sea-mango (Cerbera manghas); and frangipani (Plumeria rubra); and in the milkweeds: redheaded cotton-bush (Asclepias curassavica); balloon cotton (Asclepias fruiticosa); king's crown (Calotropis procera); and rubber vine (Cryptostegia grandifolia). The venom gland of the cane toad (Bufo marinus) also contained large quantities of cardiac glycosides. The competitive immunoassay method permits the rapid screening of specimens that are suspected to contain cardiac glycosides. Awareness of the existence of these plant and animal toxins and their dangers allows them to be avoided and poisoning prevented. The method is also useful for the confirmation of the presence of cardiac glycosides in serum in cases of poisoning. PMID:3086679

  19. A revised “earthquake report” questionaire

    USGS Publications Warehouse

    Stover, C.; Reagor, G.; Simon, R.

    1976-01-01

    The U.S geological Survey is responsible for conducting intensity and damage surveys following felt or destructive earthquakes in the United States. Shortly after a felt or damaging earthquake occurs, a canvass of the affected area is made. Specially developed questionnaires are mailed to volunteer observers located within the estimated felt area. These questionnaires, "Earthquake Reports," are filled out by the observers and returned to the Survey's National Earthquake Information Service, which is located in Colorado. They are then evaluated, and, based on answers to questions about physical effects seen or felt, each canvassed location is assigned to the various locations, they are plotted on an intensity distribution map. When all of the intensity data have been plotted, isoseismals can then be contoured through places where equal intensity was experienced. The completed isoseismal map yields a detailed picture of the earthquake, its effects, and its felt area. All of the data and maps are published quarterly in a U.S Geological Survey Circular series entitled "Earthquakes in the United States".  

  20. A century of induced earthquakes in Oklahoma?

    USGS Publications Warehouse

    Hough, Susan E.; Page, Morgan T.

    2015-01-01

    Seismicity rates have increased sharply since 2009 in the central and eastern United States, with especially high rates of activity in the state of Oklahoma. Growing evidence indicates that many of these events are induced, primarily by injection of wastewater in deep disposal wells. The upsurge in activity has raised two questions: What is the background rate of tectonic earthquakes in Oklahoma? How much has the rate varied throughout historical and early instrumental times? In this article, we show that (1) seismicity rates since 2009 surpass previously observed rates throughout the twentieth century; (2) several lines of evidence suggest that most of the significant earthquakes in Oklahoma during the twentieth century were likely induced by oil production activities, as they exhibit statistically significant temporal and spatial correspondence with disposal wells, and intensity measurements for the 1952 El Reno earthquake and possibly the 1956 Tulsa County earthquake follow the pattern observed in other induced earthquakes; and (3) there is evidence for a low level of tectonic seismicity in southeastern Oklahoma associated with the Ouachita structural belt. The 22 October 1882 Choctaw Nation earthquake, for which we estimate Mw 4.8, occurred in this zone.

  1. Long-term acceleration of aseismic slip preceding the Mw 9 Tohoku-oki earthquake: Constraints from repeating earthquakes

    NASA Astrophysics Data System (ADS)

    Mavrommatis, Andreas P.; Segall, Paul; Uchida, Naoki; Johnson, Kaj M.

    2015-11-01

    A decadal-scale deformation transient preceding the 2011 Mw 9 Tohoku-oki, Japan, earthquake was reported from continuous GPS data and interpreted as accelerating aseismic slip on the Japan Trench megathrust. Given the unprecedented nature of this transient, independent confirmation of accelerating slip is required. Here we show that changes in the recurrence intervals of repeating earthquakes on the Japan Trench megathrust in the period 1996 to 2011 are consistent with accelerating slip preceding the Tohoku-oki earthquake. All sequences of repeating earthquakes with statistically significant trends in recurrence interval (at 95% confidence) offshore south central Tohoku occurred at an accelerating rate. Furthermore, estimates of the magnitude of slip acceleration from repeating earthquakes are consistent with the completely independent geodetic estimates. From a joint inversion of the GPS and seismicity data, we infer that a substantial portion of the megathrust experienced accelerating slip, partly surrounding the eventual rupture zone of the Mw 9 earthquake.

  2. Clustered and transient earthquake sequences in mid-continents

    NASA Astrophysics Data System (ADS)

    Liu, M.; Stein, S. A.; Wang, H.; Luo, G.

    2012-12-01

    Earthquakes result from sudden release of strain energy on faults. On plate boundary faults, strain energy is constantly accumulating from steady and relatively rapid relative plate motion, so large earthquakes continue to occur so long as motion continues on the boundary. In contrast, such steady accumulation of stain energy does not occur on faults in mid-continents, because the far-field tectonic loading is not steadily distributed between faults, and because stress perturbations from complex fault interactions and other stress triggers can be significant relative to the slow tectonic stressing. Consequently, mid-continental earthquakes are often temporally clustered and transient, and spatially migrating. This behavior is well illustrated by large earthquakes in North China in the past two millennia, during which no single large earthquakes repeated on the same fault segments, but moment release between large fault systems was complementary. Slow tectonic loading in mid-continents also causes long aftershock sequences. We show that the recent small earthquakes in the Tangshan region of North China are aftershocks of the 1976 Tangshan earthquake (M 7.5), rather than indicators of a new phase of seismic activity in North China, as many fear. Understanding the transient behavior of mid-continental earthquakes has important implications for assessing earthquake hazards. The sequence of large earthquakes in the New Madrid Seismic Zone (NMSZ) in central US, which includes a cluster of M~7 events in 1811-1812 and perhaps a few similar ones in the past millennium, is likely a transient process, releasing previously accumulated elastic strain on recently activated faults. If so, this earthquake sequence will eventually end. Using simple analysis and numerical modeling, we show that the large NMSZ earthquakes may be ending now or in the near future.

  3. Seismic and Geodetic Investigation of the 1996-1998 Earthquake Swarm at Strandline Lake, Alaska

    NASA Astrophysics Data System (ADS)

    Kilgore, W.; Roman, D. C.; Power, J. A.; Hansen, R. A.; Biggs, J.

    2009-12-01

    Microearthquake (< M3.0) swarms occur frequently in volcanic environments, but do not always culminate in an eruption. Such non-eruptive swarms may be caused by stresses induced by magma intrusion, hydrothermal fluid circulation, or regional tectonic processes, such as slow-slip earthquakes. Strandline Lake, located 30 km northeast of Mount Spurr volcano in south-central Alaska, experienced a strong earthquake swarm between August 1996 and August 1998. The Alaska Volcano Observatory (AVO) catalog indicates that a total of 2,999 earthquakes were detected during the swarm period, with a maximum magnitude of Mw 3.1 and a depth range of 0-30 km below sea level (with the majority of catalog hypocenters located between 5-10 km BSL). The cumulative seismic moment of the swarm was 2.03e15 N m, equivalent to a cumulative magnitude of Mw 4.2. Because of the swarm's distance from the nearest Holocene volcanic vent, seismic monitoring was poor and gas and deformation data for the swarm period do not exist. However, combined waveforms from a dense seismic network on Mount Spurr and from several regional seismic stations allowed us to re-analyze the swarm earthquakes. We first developed a new 1-D velocity model for the Strandline Lake region by re-picking and inverting precise arrival times for 27 large Strandline Lake earthquakes. The new velocity model reduced the average RMS for these earthquakes from 0.16 to 0.11s, and the average horizontal and vertical location errors from 3.3 to 2.5 km and 4.7 to 3.0 km, respectively. Depths of the 27 earthquakes ranged from 10.5 to 22.1 km with an average depth of 16.6 km. A moderately high b-value of 1.33 was determined for the swarm period, possibly indicative of magmatic activity. However, a similarly high b-value of 1.25 was calculated for the background period. 28 well-constrained fault plane solutions for both swarm and background earthquakes indicate a diverse mixture of strike-slip, dip-slip, and reverse faulting beneath Strandline Lake. Finally, 8 Interferometric Synthetic Aperture Radar (InSAR) images spanning the swarm period unambiguously show no evidence of surface deformation. While a shallow volcanic intrusion appears to be an unlikely cause of the Strandline Lake swarm based on our new well-constrained earthquake depths and the absence of strong surface deformation, the depth range of 10.5 and 22.1 km for relocated earthquakes and the high degree of FPS heterogeneity for this swarm are similar to an earthquake swarm beneath Lake Tahoe, California in 2003 caused by a deep intrusion near the base of the crust (Smith et al, 2004, Science 305,1277-1280). This similarity suggests that a deep crustal magmatic intrusion could have occurred beneath the Strandline Lake area in 1997 and may have been responsible for the resulting microearthquake activity.

  4. Continuing Megathrust Earthquake Potential in northern Chile after the 2014 Iquique Earthquake Sequence

    NASA Astrophysics Data System (ADS)

    Hayes, G. P.; Herman, M. W.; Barnhart, W. D.; Furlong, K. P.; Riquelme, S.; Benz, H.; Bergman, E.; Barrientos, S. E.; Earle, P. S.; Samsonov, S. V.

    2014-12-01

    The seismic gap theory, which identifies regions of elevated hazard based on a lack of recent seismicity in comparison to other portions of a fault, has successfully explained past earthquakes and is useful for qualitatively describing where future large earthquakes might occur. A large earthquake had been expected in the subduction zone adjacent to northern Chile, which until recently had not ruptured in a megathrust earthquake since a M~8.8 event in 1877. On April 1 2014, a M 8.2 earthquake occurred within this northern Chile seismic gap, offshore of the city of Iquique; the size and spatial extent of the rupture indicate it was not the earthquake that had been anticipated. Here, we present a rapid assessment of the seismotectonics of the March-April 2014 seismic sequence offshore northern Chile, including analyses of earthquake (fore- and aftershock) relocations, moment tensors, finite fault models, moment deficit calculations, and cumulative Coulomb stress transfer calculations over the duration of the sequence. This ensemble of information allows us to place the current sequence within the context of historic seismicity in the region, and to assess areas of remaining and/or elevated hazard. Our results indicate that while accumulated strain has been released for a portion of the northern Chile seismic gap, significant sections have not ruptured in almost 150 years. These observations suggest that large-to-great sized megathrust earthquakes will occur north and south of the 2014 Iquique sequence sooner than might be expected had the 2014 events ruptured the entire seismic gap.

  5. The 2011 Tohoku earthquake (Mw 9.0) sequence and subduction dynamics in Western Pacific and East Asia

    NASA Astrophysics Data System (ADS)

    Zhao, Dapeng

    2015-02-01

    We review recent findings on the causal mechanism of the great 2011 Tohoku earthquake (Mw 9.0) sequence and related issues on seismic structure and subduction dynamics in Western Pacific and East Asia. High-resolution tomography revealed significant lateral heterogeneities in the interplate megathrust zone beneath the Tohoku, South Kuril and Southwest Japan forearc regions. Large megathrust earthquakes since 1900 generally occurred in or around high-velocity (high-V) patches in the megathrust zone, which may reflect asperities resulting from subducted seamounts, oceanic ridges and other topographic highs on the Pacific seafloor. In contrast, low-velocity (low-V) patches in the megathrust zone may contain more sediments and fluids, where the subducting oceanic plate and the overlying continental plate are less coupled or even decoupled. The nucleation of large crustal earthquakes in the Japan Islands, including the 11 April 2011 Iwaki earthquake (M 7.0) in SE Tohoku, is affected by arc magma and fluids resulting from slab dehydration. The Philippine Sea plate has subducted aseismically down to 430-460 km depth under East China Sea, Tsushima Strait and Japan Sea. A window in the aseismic Philippine Sea slab is detected, which may be caused by splitting of weak parts of the slab at the subducted ridges (e.g., Kyushu-Paula ridge) and hot upwelling in the mantle wedge above the Pacific slab. The intraplate volcanism in Northeast Asia is caused by hot and wet upwelling flows in the big mantle wedge above the stagnant Pacific slab in the mantle transition zone. Frequent generation of large deep earthquakes (>500 km depth) in the Pacific slab may supply additional fluids preserved in the slab to the mantle wedge under the Changbai volcano, making Changbai the largest and most active intraplate volcano in Northeast Asia. Fluids may be involved in nucleation and rupture processes of all types of earthquakes.

  6. OMG Earthquake! Can Twitter improve earthquake response?

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    The U.S. Geological Survey (USGS) is investigating how the social networking site Twitter, a popular service for sending and receiving short, public, text messages, can augment its earthquake response products and the delivery of hazard information. The goal is to gather near real-time, earthquake-related messages (tweets) and provide geo-located earthquake detections and rough maps of the corresponding felt areas. Twitter and other social Internet technologies are providing the general public with anecdotal earthquake hazard information before scientific information has been published from authoritative sources. People local to an event often publish information within seconds via these technologies. In contrast, depending on the location of the earthquake, scientific alerts take between 2 to 20 minutes. Examining the tweets following the March 30, 2009, M4.3 Morgan Hill earthquake shows it is possible (in some cases) to rapidly detect and map the felt area of an earthquake using Twitter responses. Within a minute of the earthquake, the frequency of “earthquake” tweets rose above the background level of less than 1 per hour to about 150 per minute. Using the tweets submitted in the first minute, a rough map of the felt area can be obtained by plotting the tweet locations. Mapping the tweets from the first six minutes shows observations extending from Monterey to Sacramento, similar to the perceived shaking region mapped by the USGS “Did You Feel It” system. The tweets submitted after the earthquake also provided (very) short first-impression narratives from people who experienced the shaking. Accurately assessing the potential and robustness of a Twitter-based system is difficult because only tweets spanning the previous seven days can be searched, making a historical study impossible. We have, however, been archiving tweets for several months, and it is clear that significant limitations do exist. The main drawback is the lack of quantitative information such as epicenter, magnitude, and strong-motion recordings. Without quantitative data, prioritization of response measures, including building and infrastructure inspection, are not possible. The main advantage of Twitter is speed, especially in sparsely instrumented areas. A Twitter based system potentially could provide a quick notification that there was a possible event and that seismographically derived information will follow. If you are interested in learning more, follow @USGSted on Twitter.

  7. Correlating precursory declines in groundwater radon with earthquake magnitude.

    PubMed

    Kuo, T

    2014-01-01

    Both studies at the Antung hot spring in eastern Taiwan and at the Paihe spring in southern Taiwan confirm that groundwater radon can be a consistent tracer for strain changes in the crust preceding an earthquake when observed in a low-porosity fractured aquifer surrounded by a ductile formation. Recurrent anomalous declines in groundwater radon were observed at the Antung D1 monitoring well in eastern Taiwan prior to the five earthquakes of magnitude (Mw ): 6.8, 6.1, 5.9, 5.4, and 5.0 that occurred on December 10, 2003; April 1, 2006; April 15, 2006; February 17, 2008; and July 12, 2011, respectively. For earthquakes occurring on the longitudinal valley fault in eastern Taiwan, the observed radon minima decrease as the earthquake magnitude increases. The above correlation has been proven to be useful for early warning local large earthquakes. In southern Taiwan, radon anomalous declines prior to the 2010 Mw 6.3 Jiasian, 2012 Mw 5.9 Wutai, and 2012 ML 5.4 Kaohsiung earthquakes were also recorded at the Paihe spring. For earthquakes occurring on different faults in southern Taiwan, the correlation between the observed radon minima and the earthquake magnitude is not yet possible. PMID:23550908

  8. EVIDENCE FOR THREE MODERATE TO LARGE PREHISTORIC HOLOCENE EARTHQUAKES NEAR CHARLESTON, S. C.

    USGS Publications Warehouse

    Weems, Robert E.; Obermeier, Stephen F.; Pavich, Milan J.; Gohn, Gregory S.; Rubin, Meyer; Phipps, Richard L.; Jacobson, Robert B.

    1986-01-01

    Earthquake-induced liquefaction features (sand blows), found near Hollywood, S. C. , have yielded abundant clasts of humate-impregnated sand and sparse pieces of wood. Radiocarbon ages for the humate and wood provide sufficient control on the timing of the earthquakes that produced the sand blows to indicate that at least three prehistoric liquefaction-producing earthquakes (m//b approximately 5. 5 or larger) have occurred within the last 7,200 years. The youngest documented prehistoric earthquake occurred around 800 A. D. A few fractures filled with virtually unweathered sand, but no large sand blows, can be assigned confidently to the historic 1886 Charleston earthquake.

  9. Modified-Fibonacci-Dual-Lucas method for earthquake prediction

    NASA Astrophysics Data System (ADS)

    Boucouvalas, A. C.; Gkasios, M.; Tselikas, N. T.; Drakatos, G.

    2015-06-01

    The FDL method makes use of Fibonacci, Dual and Lucas numbers and has shown considerable success in predicting earthquake events locally as well as globally. Predicting the location of the epicenter of an earthquake is one difficult challenge the other being the timing and magnitude. One technique for predicting the onset of earthquakes is the use of cycles, and the discovery of periodicity. Part of this category is the reported FDL method. The basis of the reported FDL method is the creation of FDL future dates based on the onset date of significant earthquakes. The assumption being that each occurred earthquake discontinuity can be thought of as a generating source of FDL time series The connection between past earthquakes and future earthquakes based on FDL numbers has also been reported with sample earthquakes since 1900. Using clustering methods it has been shown that significant earthquakes (<6.5R) can be predicted with very good accuracy window (+-1 day). In this contribution we present an improvement modification to the FDL method, the MFDL method, which performs better than the FDL. We use the FDL numbers to develop possible earthquakes dates but with the important difference that the starting seed date is a trigger planetary aspect prior to the earthquake. Typical planetary aspects are Moon conjunct Sun, Moon opposite Sun, Moon conjunct or opposite North or South Modes. In order to test improvement of the method we used all +8R earthquakes recorded since 1900, (86 earthquakes from USGS data). We have developed the FDL numbers for each of those seeds, and examined the earthquake hit rates (for a window of 3, i.e. +-1 day of target date) and for <6.5R. The successes are counted for each one of the 86 earthquake seeds and we compare the MFDL method with the FDL method. In every case we find improvement when the starting seed date is on the planetary trigger date prior to the earthquake. We observe no improvement only when a planetary trigger coincided with the earthquake date and in this case the FDL method coincides with the MFDL. Based on the MDFL method we present the prediction method capable of predicting global events or localized earthquakes and we will discuss the accuracy of the method in as far as the prediction and location parts of the method. We show example calendar style predictions for global events as well as for the Greek region using planetary alignment seeds.

  10. Earthquake casualty models within the USGS Prompt Assessment of Global Earthquakes for Response (PAGER) system

    USGS Publications Warehouse

    Jaiswal, Kishor; Wald, David J.; Earle, Paul; Porter, Keith A.; Hearne, Mike

    2011-01-01

    Since the launch of the USGS’s Prompt Assessment of Global Earthquakes for Response (PAGER) system in fall of 2007, the time needed for the U.S. Geological Survey (USGS) to determine and comprehend the scope of any major earthquake disaster anywhere in the world has been dramatically reduced to less than 30 min. PAGER alerts consist of estimated shaking hazard from the ShakeMap system, estimates of population exposure at various shaking intensities, and a list of the most severely shaken cities in the epicentral area. These estimates help government, scientific, and relief agencies to guide their responses in the immediate aftermath of a significant earthquake. To account for wide variability and uncertainty associated with inventory, structural vulnerability and casualty data, PAGER employs three different global earthquake fatality/loss computation models. This article describes the development of the models and demonstrates the loss estimation capability for earthquakes that have occurred since 2007. The empirical model relies on country-specific earthquake loss data from past earthquakes and makes use of calibrated casualty rates for future prediction. The semi-empirical and analytical models are engineering-based and rely on complex datasets including building inventories, time-dependent population distributions within different occupancies, the vulnerability of regional building stocks, and casualty rates given structural collapse.

  11. Amending and complicating Chile’s seismic catalog with the Santiago earthquake of 7 August 1580

    NASA Astrophysics Data System (ADS)

    Cisternas, Marco; Torrejón, Fernando; Gorigoitia, Nicolás

    2012-02-01

    Historical earthquakes of Chile's metropolitan region include a previously uncatalogued earthquake that occurred on 7 August 1580 in the Julian calendar. We found an authoritative account of this earthquake in a letter written four days later in Santiago and now archived in Spain. The letter tells of a destructive earthquake that struck Santiago and its environs. In its reported effects it surpassed the one in the same city in 1575, until now presumed to be the only earthquake in the first century of central Chile's written history. It is not yet possible to identify the source of the 1580 earthquake but viable candidates include both the plate boundary and Andean faults at shallows depths around Santiago. By occurring just five years after another large earthquake, the 1580 earthquake casts doubt on the completeness of the region's historical earthquake catalog and the periodicity of its large earthquakes. That catalog, based on eyewitness accounts compiled mainly by Alexander Perrey and Fernand Montessus de Ballore, tells of large Chile's metropolitan region earthquakes in 1575, 1647, 1730, 1822, 1906 and 1985. The addition of a large earthquake in 1580 implies greater variability in recurrence intervals and may also mean greater variety in earthquake sources.

  12. Tsunami history of an Oregon coastal lake reveals a 4600 yr record of great earthquakes on the Cascadia subduction zone

    USGS Publications Warehouse

    Kelsey, H.M.; Nelson, A.R.; Hemphill-Haley, E.; Witter, R.C.

    2005-01-01

    Bradley Lake, on the southern Oregon coastal plain, records local tsunamis and seismic shaking on the Cascadia subduction zone over the last 7000 yr. Thirteen marine incursions delivered landward-thinning sheets of sand to the lake from nearshore, beach, and dune environments to the west. Following each incursion, a slug of marine water near the bottom of the freshwater lake instigated a few-year-to-several-decade period of a brackish (??? 4??? salinity) lake. Four additional disturbances without marine incursions destabilized sideslopes and bottom sediment, producing a suspension deposit that blanketed the lake bottom. Considering the magnitude and duration of the disturbances necessary to produce Bradley Lake's marine incursions, a local tsunami generated by a great earthquake on the Cascadia subduction zone is the only accountable mechanism. Extreme ocean levels must have been at least 5-8 m above sea level, and the cumulative duration of each marine incursion must have been at least 10 min. Disturbances without marine incursions require seismic shaking as well. Over the 4600 yr period when Bradley Lake was an optimum tsunami recorder, tsunamis from Cascadia plate-boundary earthquakes came in clusters. Between 4600 and 2800 cal yr B.P., tsunamis occurred at the average frequency of ??? 3-4 every 1000 yr. Then, starting ???2800 cal yr B.P., there was a 930-1260 yr interval with no tsunamis. That gap was followed by a ???1000 yr period with 4 tsunamis. In the last millennium, a 670-750 yr gap preceded the A.D. 1700 earthquake and tsunami. The A.D. 1700 earthquake may be the first of a new cluster of plate-boundary earthquakes and accompanying tsunamis. Local tsunamis entered Bradley Lake an average of every 390 yr, whereas the portion of the Cascadia plate boundary that underlies Bradley Lake ruptured in a great earthquake less frequently, about once every 500 yr. Therefore, the entire length of the subduction zone does not rupture in every earthquake, and Bradley Lake has recorded earthquakes caused by rupture along the entire length of the Cascadia plate boundary as well as earthquakes caused by rupture of shorter segments of the boundary. The tsunami record from Bradley Lake indicates that at times, most recently ???1700 yr B.P., overlapping or adjoining segments of the Cascadia plate boundary ruptured within decades of each other. ?? 2005 Geological Society of America.

  13. Study of Low-Frequency Earth motions from Earthquakes and a Hurricane using a Modified Standard Seismometer

    NASA Astrophysics Data System (ADS)

    Peters, R. D.

    2004-12-01

    The modification of a WWSSN Sprengnether vertical seismometer has resulted in significantly improved performance at low frequencies. Instead of being used as a velocity detector as originally designed, the Faraday subsystem is made to function as an actuator to provide a type of force feedback. Added to the instrument to detect ground motions is an array form of the author's symmetric differential capacitive (SDC) sensor. The feedback circuit is not conventional, but rather is used to eliminate long-term drift by placing between sensor and actuator an operational amplifier integrator having a time constant of several thousand seconds. Signal to noise ratio at low frequencies is increased, since the modified instrument does not suffer from the 20dB/decade falloff in sensitivity that characterizes conventional force-feedback seismometers. A Hanning-windowed FFT algorithm is employed in the analysis of recorded earthquakes, including that of the very large Indonesia earthquake (M 7.9) of 25 July 2004. The improved low frequency response allows the study of the free oscillations of the Earth that accompany large earthquakes. Data will be provided showing oscillations with spectral components in the vicinity of 1 mHz, that frequently have been observed with this instrument to occur both before as well as after an earthquake. Additionally, microseisms and other interesting data will be shown from records collected by the instrument as Hurricane Charley moved across Florida and up the eastern seaboard.

  14. Earthquake history of Texas

    USGS Publications Warehouse

    von Hake, C. A.

    1977-01-01

    Seventeen earthquakes, intensity V or greater, have centered in Texas since 1882, when the first shock was reported. The strongest earthquake, a maximum intensity VIII, was in western Texas in 1931 and was felt over 1 165 000 km 2. Three shocks in the Panhandle region in 1925, 1936, and 1943 were widely felt. 

  15. Children's Beliefs about Earthquakes.

    ERIC Educational Resources Information Center

    Ross, Katharyn E. K.; Shuell, Thomas J.

    1993-01-01

    Summarizes the results of three related studies whose overall purpose was to determine elementary students' conceptions about earthquakes at two widely separated locations in the United States. Certain topics, such as the cause of earthquakes, seemed to cause difficulty for students. New definitional responses emerged in the studies that took…

  16. Earthquake Monitoring in Haiti

    Following the devastating 2010 Haiti earthquake, the USGS has been helping with earthquake awareness and monitoring in the country, with continued support from the U.S. Agency for International Development (USAID). This assistance has helped the Bureau des Mines et de l'Energie (BME) in Port-au-Prin...

  17. Intermediate- and long-term earthquake prediction.

    PubMed Central

    Sykes, L R

    1996-01-01

    Progress in long- and intermediate-term earthquake prediction is reviewed emphasizing results from California. Earthquake prediction as a scientific discipline is still in its infancy. Probabilistic estimates that segments of several faults in California will be the sites of large shocks in the next 30 years are now generally accepted and widely used. Several examples are presented of changes in rates of moderate-size earthquakes and seismic moment release on time scales of a few to 30 years that occurred prior to large shocks. A distinction is made between large earthquakes that rupture the entire downdip width of the outer brittle part of the earth's crust and small shocks that do not. Large events occur quasi-periodically in time along a fault segment and happen much more often than predicted from the rates of small shocks along that segment. I am moderately optimistic about improving predictions of large events for time scales of a few to 30 years although little work of that type is currently underway in the United States. Precursory effects, like the changes in stress they reflect, should be examined from a tensorial rather than a scalar perspective. A broad pattern of increased numbers of moderate-size shocks in southern California since 1986 resembles the pattern in the 25 years before the great 1906 earthquake. Since it may be a long-term precursor to a great event on the southern San Andreas fault, that area deserves detailed intensified study. Images Fig. 1 PMID:11607658

  18. Response of Sensitive Behaviors to Frequent Measurement

    PubMed Central

    2014-01-01

    We study the influence of frequent survey measurement on behavior. Widespread access to the Internet has made important breakthroughs in frequent measurement possible—potentially revolutionizing social science measurement of processes that change quickly over time. One key concern about using such frequent measurement is that it may influence the behavior being studied. We investigate this possibility using both a population-based experiment with random assignment to participation in a weekly journal for twelve months (versus no journal) and a large scale population-based journal-keeping study with weekly measurement for 30 months. Results reveal few of the measured behaviors are correlated with assignment to frequent measurement. Theoretical reasoning regarding the likely behavioral response to frequent measurement correctly predicts domains most vulnerable to this possibility. Overall, however, we found little evidence of behavioral response to frequent measurement. PMID:25432599

  19. Response of sensitive behaviors to frequent measurement.

    PubMed

    Axinn, William G; Jennings, Elyse A; Couper, Mick P

    2015-01-01

    We study the influence of frequent survey measurement on behavior. Widespread access to the Internet has made important breakthroughs in frequent measurement possible-potentially revolutionizing social science measurement of processes that change quickly over time. One key concern about using such frequent measurement is that it may influence the behavior being studied. We investigate this possibility using both a population-based experiment with random assignment to participation in a weekly journal for twelve months (versus no journal) and a large-scale, population-based, journal-keeping study with weekly measurement for 30 months. Results reveal few of the measured behaviors are correlated with assignment to frequent measurement. Theoretical reasoning regarding the likely behavioral response to frequent measurement correctly predicts domains most vulnerable to this possibility. Overall, however, we found little evidence of behavioral response to frequent measurement. PMID:25432599

  20. Retrospective stress-forecasting of earthquakes

    NASA Astrophysics Data System (ADS)

    Gao, Yuan; Crampin, Stuart

    2015-04-01

    Observations of changes in azimuthally varying shear-wave splitting (SWS) above swarms of small earthquakes monitor stress-induced changes to the stress-aligned vertical microcracks pervading the upper crust, lower crust, and uppermost ~400km of the mantle. (The microcracks are intergranular films of hydrolysed melt in the mantle.) Earthquakes release stress, and an appropriate amount of stress for the relevant magnitude must accumulate before each event. Iceland is on an extension of the Mid-Atlantic Ridge, where two transform zones, uniquely run onshore. These onshore transform zones provide semi-continuous swarms of small earthquakes, which are the only place worldwide where SWS can be routinely monitored. Elsewhere SWS must be monitored above temporally-active occasional swarms of small earthquakes, or in infrequent SKS and other teleseismic reflections from the mantle. Observations of changes in SWS time-delays are attributed to stress-induced changes in crack aspect-ratios allowing stress-accumulation and stress-relaxation to be identified. Monitoring SWS in SW Iceland in 1988, stress-accumulation before an impending earthquake was recognised and emails were exchanged between the University of Edinburgh (EU) and the Iceland Meteorological Office (IMO). On 10th November 1988, EU emailed IMO that a M5 earthquake could occur soon on a seismically-active fault plane where seismicity was still continuing following a M5.1 earthquake six-months earlier. Three-days later, IMO emailed EU that a M5 earthquake had just occurred on the specified fault-plane. We suggest this is a successful earthquake stress-forecast, where we refer to the procedure as stress-forecasting earthquakes as opposed to predicting or forecasting to emphasise the different formalism. Lack of funds has prevented us monitoring SWS on Iceland seismograms, however, we have identified similar characteristic behaviour of SWS time-delays above swarms of small earthquakes which have enabled us to retrospectively stress-forecasting ~17 earthquakes ranging in magnitude from a M1.7 swarm event in N Iceland, to the 1999 M7.7 Chi-Chi Earthquake in Taiwan, and the 2004 Mw9.2 Sumatra-Andaman Earthquake (SAE). Before SAE, the changes in SWS were observed at seismic stations in Iceland at a distance of ~10,500km the width of the Eurasian Plate, from Indonesia demonstrating the 'butterfly wings' sensitivity of the New Geophysics of a critically microcracked Earth. At that time, the sensitivity of the phenomena had not been recognised, and the SAE was not stress-forecast. These results have been published at various times in various formats in various journals. This presentation displays all the results in a normalised format that allows the similarities to be recognised, confirming that observations of SWS time-delays can stress-forecast the times, magnitudes, and in some circumstances fault-breaks, of impending earthquakes. Papers referring to these developments can be found in geos.ed.ac.uk/home/scrampin/opinion. Also see abstracts in EGU2015 Sessions: Crampin & Gao (SM1.1), Liu & Crampin (NH2.5), and Crampin & Gao (GD.1).

  1. A fluid-driven earthquake swarm on the margin of the Yellowstone caldera

    USGS Publications Warehouse

    Shelly, David R.; Hill, David P.; Massin, Frederick; Farrell, Jamie; Smith, Robert B.; Taira, Taka'aki

    2013-01-01

    Over the past several decades, the Yellowstone caldera has experienced frequent earthquake swarms and repeated cycles of uplift and subsidence, reflecting dynamic volcanic and tectonic processes. Here, we examine the detailed spatial-temporal evolution of the 2010 Madison Plateau swarm, which occurred near the northwest boundary of the Yellowstone caldera. To fully explore the evolution of the swarm, we integrated procedures for seismic waveform-based earthquake detection with precise double-difference relative relocation. Using cross-correlation of continuous seismic data and waveform templates constructed from cataloged events, we detected and precisely located 8710 earthquakes during the three-week swarm, nearly four times the number of events included in the standard catalog. This high-resolution analysis reveals distinct migration of earthquake activity over the course of the swarm. The swarm initiated abruptly on January 17, 2010 at about 10 km depth and expanded dramatically outward (both shallower and deeper) over time, primarily along a NNW-striking, ~55º ENE-dipping structure. To explain these characteristics, we hypothesize that the swarm was triggered by the rupture of a zone of confined high-pressure aqueous fluids into a pre-existing crustal fault system, prompting release of accumulated stress. The high-pressure fluid injection may have been accommodated by hybrid shear and dilatational failure, as is commonly observed in exhumed hydrothermally affected fault zones. This process has likely occurred repeatedly in Yellowstone as aqueous fluids exsolved from magma migrate into the brittle crust, and it may be a key element in the observed cycles of caldera uplift and subsidence.

  2. Demand surge following earthquakes

    USGS Publications Warehouse

    Olsen, Anna H.

    2012-01-01

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

  3. Earthquake history of Mississippi

    USGS Publications Warehouse

    von Hake, C. A.

    1974-01-01

    Since its admission into the Union in 1817, Mississippi has had only four earthquakes of intensity V or greater within its borders. Although the number of earthquakes known to have been centered within Mississippi's boundaries is small, the State has been affected by numerous shocks located in neighboring States. In 1811 and 1812, a series of great earthquakes near the New Madrid Missouri area was felt in Mississippi as far south as the gulf coast. The New Madrid series caused the banks of the Mississippi River to cave in as far as Vicksburg, mroe than 300 miles from the epicentral region. As a result of this great earthquake series, the northwest corner of Mississippi is in seismic risk zone 3, the highest risk zone. Expect for the new Madrid series, effects in Mississippi from earthquakes located outside of the State have been less than intensity V. 

  4. Earthquake history of Pennsylvania

    USGS Publications Warehouse

    von Hake, C. A.

    1976-01-01

    Record of early earthquakes in Northeastern United States provide limited information on effects in pennsylvania until 1737, 55 years after the first permanent settlement was established. A very severe earthquake that centered in the St.Lawrence River region in 1663 may have been felt in Pennsylvania, but historical accounts are not definite. Likewise, a damaging shock at Newbury, Mass., in 1727 probably affected towns in Pennsylvania. A strong earthquake on December 18, 1737, toppled chimneys at New York City and was reported felt at Boston, Mass., Philadelphia, Pa. and New Castle, Del. Other shocks with origins outside the State were felt in 1758, 1783, and 1791. Since 1800, when two earthquakes (March 17 and November 29) were reported as "severe" at Philadelphia, 16 tremors of intensity V or greater (Modified Mercalli Scale) have originated within the State. On November 11 and 14, 1840, sever earthquakes at Philadelphia were accompnaied by a great and unusual swell on the Delaware River. 

  5. Observing the Greatest Earthquakes

    NASA Astrophysics Data System (ADS)

    Atwater, Brian; Barrientos, Sergio; Cifuentes, Inís; Cisternas, Marco; Wang, Kelin

    2010-11-01

    AGU Chapman Conference on Giant Earthquakes and Their Tsunamis; Viña del Mar and Valparaíso, Chile, 16-20 May 2010 ; An AGU Chapman Conference commemorated the fiftieth anniversary of the 1960 M 9.5 Chile earthquake. Participants reexamined this earthquake, the largest ever recorded instrumentally, and compared it with Chile's February 2010 M 8.8 earthquake. They also addressed the giant earthquake potential of subduction zones worldwide and strategies for reducing losses due to tsunamis. The conference drew 96 participants from 18 countries, and it reached out to public audiences in Chile. Its program and abstracts are posted at http://www.agu.org/meetings/chapman/2010/acall/pdf/Scientific_Program.pdf.

  6. Modeling earthquake dynamics

    NASA Astrophysics Data System (ADS)

    Charpentier, Arthur; Durand, Marilou

    2015-07-01

    In this paper, we investigate questions arising in Parsons and Geist (Bull Seismol Soc Am 102:1-11, 2012). Pseudo causal models connecting magnitudes and waiting times are considered, through generalized regression. We do use conditional model (magnitude given previous waiting time, and conversely) as an extension to joint distribution model described in Nikoloulopoulos and Karlis (Environmetrics 19: 251-269, 2008). On the one hand, we fit a Pareto distribution for earthquake magnitudes, where the tail index is a function of waiting time following previous earthquake; on the other hand, waiting times are modeled using a Gamma or a Weibull distribution, where parameters are functions of the magnitude of the previous earthquake. We use those two models, alternatively, to generate the dynamics of earthquake occurrence, and to estimate the probability of occurrence of several earthquakes within a year or a decade.

  7. Protecting Your Family From Earthquakes-The Seven Steps to Earthquake Safety (in Spanish and English)

    USGS Publications Warehouse

    Developed by American Red Cross, Asian Pacific Fund, California Earthquake Authority, Governor's Office of Emergency Services, New America Media, U.S. Department of Homeland Security Federal Emergency Management Agency, and U.S. Geological Survey

    2007-01-01

    This book is provided here to share an important message on emergency preparedness. Historically, we have suffered earthquakes here in the San Francisco Bay Area that have caused severe hardship for residents and incredible damage to our cities. It is likely we will experience a severe earthquake within the next 30 years. Many of us come from other countries where we have experienced earth- quakes, so we believe that we understand them. However, the way we prepare for earthquakes in our home country may be different from the way it is necessary to prepare for earthquakes here. Very f w people die from collapsing buildings in the Bay Area because most structures are built to stand up to the shaking. But it is quite possible that your family will be without medical care or grocery stores and separated from one another for several days to weeks. It will ultimately be up to you to keep your family safe until help arrives, so we are asking you to join us in learning to take care of your family before, during, and after an earthquake. The first step is to read this book. Everyone in your family, children and adults, can learn how to prepare for an earthquake. Then take advantage of the American Red Cross Earthquake Preparedness training courses offered in your community. These preparedness courses are free, and also offered in Spanish and available to everyone in the community regardless of family history, leg al status, gender, or age. We encourage you to take one of these free training workshops. Look on the back cover for more information. Remember that an earthquake can occur without warning, and the only way that we can reduce the harm caused by earthquakes is to be prepared. Get Prepared!

  8. Earthquake fault superhighways

    NASA Astrophysics Data System (ADS)

    Robinson, D. P.; Das, S.; Searle, M. P.

    2010-10-01

    Motivated by the observation that the rare earthquakes which propagated for significant distances at supershear speeds occurred on very long straight segments of faults, we examine every known major active strike-slip fault system on land worldwide and identify those with long (> 100 km) straight portions capable not only of sustained supershear rupture speeds but having the potential to reach compressional wave speeds over significant distances, and call them "fault superhighways". The criteria used for identifying these are discussed. These superhighways include portions of the 1000 km long Red River fault in China and Vietnam passing through Hanoi, the 1050 km long San Andreas fault in California passing close to Los Angeles, Santa Barbara and San Francisco, the 1100 km long Chaman fault system in Pakistan north of Karachi, the 700 km long Sagaing fault connecting the first and second cities of Burma, Rangoon and Mandalay, the 1600 km Great Sumatra fault, and the 1000 km Dead Sea fault. Of the 11 faults so classified, nine are in Asia and two in North America, with seven located near areas of very dense populations. Based on the current population distribution within 50 km of each fault superhighway, we find that more than 60 million people today have increased seismic hazards due to them.

  9. The mass balance of earthquakes and earthquake sequences

    NASA Astrophysics Data System (ADS)

    Marc, O.; Hovius, N.; Meunier, P.

    2016-04-01

    Large, compressional earthquakes cause surface uplift as well as widespread mass wasting. Knowledge of their trade-off is fragmentary. Combining a seismologically consistent model of earthquake-triggered landsliding and an analytical solution of coseismic surface displacement, we assess how the mass balance of single earthquakes and earthquake sequences depends on fault size and other geophysical parameters. We find that intermediate size earthquakes (Mw 6-7.3) may cause more erosion than uplift, controlled primarily by seismic source depth and landscape steepness, and less so by fault dip and rake. Such earthquakes can limit topographic growth, but our model indicates that both smaller and larger earthquakes (Mw < 6, Mw > 7.3) systematically cause mountain building. Earthquake sequences with a Gutenberg-Richter distribution have a greater tendency to lead to predominant erosion, than repeating earthquakes of the same magnitude, unless a fault can produce earthquakes with Mw > 8 or more.

  10. Mental health training experiences among Haitian healthcare workers post-earthquake 2010

    PubMed Central

    Cianelli, R.; Wilkinson, C.; Mitchell, E.; Anglade, D.; Nicolas, G.; Mitrani, V.; Peragallo, N.

    2014-01-01

    Background After the 2010 earthquake in Haiti, the large number of persons with major limb damage, amputations, shock, trauma, anxiety and depression placed a severe strain on mental health (MH) services. Purpose This qualitative study describes the impact and acceptability of a Mental Health Training Program (MHTP) implemented in the north of Haiti after the earthquake. Methods A total of 113 healthcare workers (HCWs) participated in a training program designed to build local MH care capacity. The training curriculum draws on literature related to MH and the impact of the Haiti earthquake. Two focus groups were conducted with 16 HCWs; discussions centred on the personal and professional impact and acceptability of the training program. Discussion Results demonstrated that the MHTP changed the HCWs perceptions about MH issues and provided them with the knowledge and skills to respond to growing community MH needs. Acceptability of the MHTP was related to the content covered, to the delivery mode of the content and to the cultural appropriateness of the program. Conclusions Disasters of different types will continue to occur and to impact MH in communities around the world. MH training will allow nurses to quickly and effectively respond to disasters. A coordinated emergency plan that is subject to frequent review, rehearsal and evaluation is also essential. PMID:24251943

  11. A tectonic earthquake sequence preceding the April-May 1999 eruption of Shishaldin Volcano, Alaska

    USGS Publications Warehouse

    Moran, S.C.; Stihler, S.D.; Power, J.A.

    2002-01-01

    On 4 March 1999, a shallow ML 5.2 earthquake occurred beneath Unimak Island in the Aleutian Arc. This earthquake was located 10-15 km west of Shishaldin Volcano, a large, frequently active basaltic-andesite stratovolcano. A Strombolian eruption began at Shishaldin roughly 1 month after the mainshock, culminating in a large explosive eruption on 19 April. We address the question of whether or not the eruption caused the mainshock by computing the Coulomb stress change caused by an inflating dike on fault planes oriented parallel to the mainshock focal mechanism. We found Coulomb stress increases of ???0.1 MPa in the region of the mainshock, suggesting that magma intrusion prior to the eruption could have caused the mainshock. Satellite and seismic data indicate that magma was moving upwards beneath Shishaldin well before the mainshock. indicating that, in an overall sense, the mainshock cannot be said to have caused the eruption. However, observations of changes at the volcano following the mainshock and several large aftershocks suggest that the earthquakes may, in turn, have influenced the course of the eruption.

  12. Waveform Cross-Correlation for Improved North Texas Earthquake Locations

    NASA Astrophysics Data System (ADS)

    Phillips, M.; DeShon, H. R.; Oldham, H. R.; Hayward, C.

    2014-12-01

    In November 2013, a sequence of earthquakes began in Reno and Azle, TX, two communities located northwest of Fort Worth in an area of active oil and gas extraction. Only one felt earthquake had been reported within the area before the occurrence of probable injection-induced earthquakes at the Dallas-Fort Worth airport in 2008. The USGS National Earthquakes Information Center (NEIC) has reported 27 felt earthquakes in the Reno-Azle area through January 28, 2014. A temporary seismic network was installed beginning in December 2013 to acquire data to improve location and magnitude estimates and characterize the earthquake sequence. Here, we present high-resolution relative earthquake locations derived using differential time data from waveform cross-correlation. Cross-correlation is computed using the GISMO software suite and event relocation is done using double difference relocation techniques. Waveform cross-correlation of the local data indicates high (>70%) similarity between 4 major swarms of events lasting between 18 and 24 hours. These swarms are temporal zones of high event frequency; 1.4% of the time series data accounts for 42.1% of the identified local earthquakes. Local earthquakes are occurring along the Newark East Fault System, a NE-SW striking normal fault system previously thought inactive at depths between 2 and 8 km in the Ellenburger limestone formation and underlying Precambrian basement. Data analysis is ongoing and continued characterization of the associated fault will provide improved location estimates.

  13. Magnitude Dependent Seismic Quiescence of 2008 Wenchuan Earthquake

    NASA Astrophysics Data System (ADS)

    Suyehiro, K.; Sacks, S. I.; Takanami, T.; Smith, D. E.; Rydelek, P. A.

    2014-12-01

    The change in seismicity leading to the Wenchuan Earthquake in 2008 (Mw 7.9) has been studied by various authors based on statistics and/or pattern recognitions (Huang, 2008; Yan et al., 2009; Chen and Wang, 2010; Yi et al., 2011). We show, in particular, that the magnitude-dependent seismic quiescence is observed for the Wenchuan earthquake and that it adds to other similar observations. Such studies on seismic quiescence prior to major earthquakes include 1982 Urakawa-Oki earthquake (M 7.1) (Taylor et al., 1992), 1994 Hokkaido-Toho-Oki earthquake (Mw=8.2) (Takanami et al., 1996), 2011 Tohoku earthquake (Mw=9.0) (Katsumata, 2011). Smith and Sacks (2013) proposed a magnitude-dependent quiescence based on a physical earthquake model (Rydelek and Sacks, 1995) and demonstrated the quiescence can be reproduced by the introduction of "asperities" (dilantacy hardened zones). Actual observations indicate the change occurs in a broader area than the eventual earthquake fault zone. In order to accept the explanation, we need to verify the model as the model predicts somewhat controversial features of earthquakes such as the magnitude dependent stress drop at lower magnitude range or the dynamically appearing asperities and repeating slips in some parts of the rupture zone. We show supportive observations. We will also need to verify the dilatancy diffusion to be taking place. So far, we only seem to have indirect evidences, which need to be more quantitatively substantiated.

  14. Earthquakes and fault creep on the northern San Andreas fault

    USGS Publications Warehouse

    Nason, R.

    1979-01-01

    At present there is an absence of both fault creep and small earthquakes on the northern San Andreas fault, which had a magnitude 8 earthquake with 5 m of slip in 1906. The fault has apparently been dormant after the 1906 earthquake. One possibility is that the fault is 'locked' in some way and only produces great earthquakes. An alternative possibility, presented here, is that the lack of current activity on the northern San Andreas fault is because of a lack of sufficient elastic strain after the 1906 earthquake. This is indicated by geodetic measurements at Fort Ross in 1874, 1906 (post-earthquake), and 1969, which show that the strain accumulation in 1969 (69 ?? 10-6 engineering strain) was only about one-third of the strain release (rebound) in the 1906 earthquake (200 ?? 10-6 engineering strain). The large difference in seismicity before and after 1906, with many strong local earthquakes from 1836 to 1906, but only a few strong earthquakes from 1906 to 1976, also indicates a difference of elastic strain. The geologic characteristics (serpentine, fault straightness) of most of the northern San Andreas fault are very similar to the characteristics of the fault south of Hollister, where fault creep is occurring. Thus, the current absence of fault creep on the northern fault segment is probably due to a lack of sufficient elastic strain at the present time. ?? 1979.

  15. Interseismic Lithospheric Response of the Southern End of the Cascadia Subduction Zone Following the 1992 Cape Mendocino Earthquake

    NASA Astrophysics Data System (ADS)

    Vermeer, J.; Hemphill-Haley, M. A.

    2014-12-01

    The Cascadia subduction zone (CSZ) in the Pacific Northwest where the pacific plate is subducting beneath the North American plate may be capable of producing M 9 earthquakes. At its southern end, the CSZ terminates at the Mendocino triple junction in northern California, a region of frequent seismic activity. The 1992 M 7.1 Cape Mendocino earthquake caused up to 1.4 m of measured coseismic deformation and it is thought to have been rupture of the southern end of the CSZ. I will present static GPS monument relocation data and the positions of intertidal organisms to measure the interseismic crustal deformation in the 22 years since the 1992 event. This evidence for post- and interseismic lithospheric response may show whether the earthquake was due to rupture of the southern end of the CSZ or a subsidiary fault. Because the megathrust has higher strain rates than subsidiary faults, we expect that significant interseismic deformation should have occurred if the 1992 earthquake was on the subduction zone interface. It will also provide an estimate of whether post-seismic recovery has been occurring since that event. Although the coseismic deformation was well documented via leveling and Vertical Extent of Mortality (VEM) of sessile intertidal organisms, no post seismic work had been done to measure the interseismic deformation. This study utilizes high resolution GPS observation of established benchmarks compared with the leveling from 1992 to measure the vertical change. It also compares elevation of specific intertidal organism colonies to the elevation of living organisms following the 1992 uplift as a proxy for relative sea level change. Quantifying the interseismic deformation allows us to better understand the source of the earthquake and how the upper plate is responding to strain accumulation along the subduction zone. Significant interseismic deformation would indicate that the fault may be reloading quickly and the earthquake was likely associated with rupture of the megathrust, which has much higher strain rates than subsidiary faults. This, in turn, may suggest segmentation of the southern CSZ. Little interseismic deformation might indicate the 1992 earthquake occurred on a subsidiary fault and not the megathrust itself. Preliminary results indicate that there has been little interseismic deformation.

  16. Assessment of the earthquake forecasting approaches (case study: IRAN)

    NASA Astrophysics Data System (ADS)

    Hajizadeh, A.; Vaezi, N. F.

    2010-05-01

    An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. As well as we can say an earthquake is suddenly shaking in the ground. This is caused when rocks that are beneath the Earth's surface move and break. Scientists attempt to predict the earthquake by means of forecasting and using new technics such as GPS, InSAR, geology, knowledge of past earthquake patterns, gravimetry and etc. Earthquake forecasts declare that a temblor has a certain probability of occurring within a given time. These warnings help to governments, communities, industries and private companies to prepare for large earthquakes and conduct rescue operation and recovery efforts in the aftermath of destructive shocks. In this article we'll assess the forecasting approaches and compare their precision and other factors. Predict time of earthquake occurrence and case study in this paper are the results of this investigation. Since forewarned communities could take steps to evaluate, many of the injuries and deaths that would otherwise occur could be avoided if the government would implement this proposal. We have chosen Iran as the center of this investigation, because Iran is one of the most seismic countries. Key words: earthquake, forecasting, geodesy approaches, IRAN, precise, earth's crust

  17. Earthquake fluctuations in wells in New Jersey

    USGS Publications Warehouse

    Austin, Charles R.

    1960-01-01

    New Jersey is fortunate to be situated in a region that is relatively stable, geologically. For this reason scientists believe, on the basis of the best scientific evidence available, that the chances of New Jersey experiencing a major earthquake are very small. The last major earthquake on the east coast occurred at Charleston, S. C., in 1886. Minor shocks have been felt in New Jersey, however, from time to time. Reports of dishes being rattled or even of plaster in buildings being cracked are not uncommon. These minor disturbances are generally restricted to relatively small areas.

  18. Earthquakes induced by deep penetrating bombing?

    NASA Astrophysics Data System (ADS)

    Balassanian, Serguei Y.

    2005-11-01

    The data of M≥5 earthquakes occurred in one year before and after 4 deep penetrating bombs in the region within 500 km and 1 000 km from the shooting site are presented. The 4 bombs are those happened in 1999 Kosovo of Yugoslavia, the 1991 Baghdad of Iraq, the 2001 Tora Bora of Afghanistan, and the 2003 Kirkuk of Iraq, respectively. The data indicate that the deep penetrating bombs may have remotely triggered some earthquakes. The deep penetrating bombs in seismically active regions should be forbidden.

  19. Understanding interaction of small repeating earthquakes through models of rate-and-state faults

    NASA Astrophysics Data System (ADS)

    Chen, T.; Lui, K.; Lapusta, N.

    2012-12-01

    Due to their short recurrence times and known locations, small repeating earthquakes are widely used to study earthquake physics. Some of the repeating sequences are located close to each other and appear to interact. For example, the "San Francisco" (SF) and "Los Angeles" (LA) repeating sequences, which are targets of the San Andreas Fault Observatory at Depth (SAFOD), have a lateral separation of less than 70 m. The LA events tend to occur within 24 hours after the SF events, suggesting a triggering effect. Our goal is to study interaction of repeating earthquakes in the framework of rate-and-state fault models, in which repeating earthquakes occur on velocity-weakening patches embedded into a larger velocity-strengthening fault area. Such models can reproduce behavior of isolated repeating earthquake sequences, in particular, the scaling of their moment versus recurrence time and the response to accelerated postseismic creep (Chen and Lapusta, 2009; Chen et al., 2010). Our studies of the interaction of seismic events on two patches show that a variety of interesting behaviors. As expected based on intuition prior studies (e.g., Kato, JGR, 2004; Kaneko et al., Nature Geoscience, 2010), the two patches behave independently when they are far apart and rupture together if they are next to each other. In the intermediate range of distances, we observe triggering effects, with ruptures on the two patches clustering in time, but also other patterns, including supercycles that alternate between events that rupture a single asperity and events that rupture both asperities at the same time. When triggering occurs, smaller events tend to trigger larger events, since the nucleation of smaller events tends to be more frequent. To overcome such a pattern, and have larger events trigger smaller events as observed for the SF-LA interaction, the patch for the smaller event needs to be of the order of the nucleation size, so that the smaller event has difficulty nucleating by itself, without the external trigger. Our simulations show that, in addition to static and dynamic stress changes that a seismic event on one patch creates on the other patch, the interaction also occurs through accelerated post-seismic slip between the two patches. For a wide range of model parameters, such accelerated aseismic slip seems to be an important, and perhaps determining, factor, as triggered events nucleate shortly after the postseismic slip front created by the event on one patch reaches the other patch. We will report on the results of our current work aimed at quantifying the relative importance of the three triggering mechanisms and their effect on the degree of interaction.

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

    SciTech Connect

    Saragoni, G. Rodolfo

    2008-07-08

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

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

    NASA Astrophysics Data System (ADS)

    Saragoni, G. Rodolfo

    2008-07-01

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

  2. The 2014 M 6.0 South Napa Earthquake in the Context of the Earthquake Cycle in the San Francisco Bay Area

    NASA Astrophysics Data System (ADS)

    Jaume, S. C.

    2014-12-01

    The 2014 M 6.0 South Napa earthquake is the second M ≥ 5.5 earthquake to occur in the San Francisco Bay region since the 1989 M 7.0 Loma Prieta earthquake. This poster will examine how this earthquake fits into the earthquake history of the Bay region, which has shown considerable variation in the rate of moderate (M 5.5-6.5) earthquakes. A number of models have been developed to explain these changes in moderate earthquake rates, including the Accelerating Moment Release model (e.g., Sykes and Jaumé, Nature, 1990; Bufe and Varnes, J. Geophys. Res., 1993) and the Stress Shadow model (e.g., Harris and Simpson, J. Geophys. Res., 1998). In addition, various groups have made projections of future earthquake activity in the San Francisco Bay region, including the Working Group on California Earthquake Probabilities (Field et al., USGS OFR, 2008) and Bebbington et al. (PAGEOPH, 2010), utilizing different physical models for earthquake occurrence. In my poster I will compare and contrast these different views of seismicity in the Bay region and where the 2014 South Napa earthquake fits into them. In particular, I will explore what these different models imply for future moderate earthquake occurrence and hazards thereof.

  3. Cooperative earthquake research between the United States and the People's Republic of China

    SciTech Connect

    Russ, D.P.; Johnson, L.E.

    1986-01-01

    This paper describes cooperative research by scientists of the US and the People's Republic of China (PRC) which has resulted in important new findings concerning the fundamental characteristics of earthquakes and new insight into mitigating earthquake hazards. There have been over 35 projects cooperatively sponsored by the Earthquake Studies Protocol in the past 5 years. The projects are organized into seven annexes, including investigations in earthquake prediction, intraplate faults and earthquakes, earthquake engineering and hazards investigation, deep crustal structure, rock mechanics, seismology, and data exchange. Operational earthquake prediction experiments are currently being developed at two primary sites: western Yunnan Province near the town of Xiaguan, where there are several active faults, and the northeast China plain, where the devastating 1976 Tangshan earthquake occurred.

  4. Seismic characteristics of outer-rise earthquakes in the different seismic coupling subduction zones

    NASA Astrophysics Data System (ADS)

    Lee, Hsin-Hua; Lin, Jing-Yi

    2013-04-01

    Characterizing the seismogenic zone of major subduction plate boundaries provides us a possible to reduce large earthquakes hazard. In the past several decades, many scientists have analyzed various geophysical methods and datasets, such as seismic and geodetic ground motion data, historical tsunami deposits, aftershock distributions, and seafloor bathymetry, trying to understand the mechanisms behind great devastating earthquakes, and to estimate the probability of a major earthquake occurrence in the future. In this study, by using the global earthquake catalog (GCMT) from January 1, 1976 to December 31, 2011. We firstly re-examines the outer-rise earthquake model proposed by the Christensen (1988) at the subduction zones suggested to have different coupling levels. The compressive stress cumulated during the subducting processes are often reflected by the occurrence of compressional outer-rise earthquakes. Thus, in the region where the compressional outer-rise earthquakes take place without any corresponding large underthrusting earthquakes, the seismic potential is usually considered to be high. We re-examined the high seismic potential areas determined by this criteria in Christensen (1988) and confirm that the large underthrusting earthquakes did really occur in the 30 years following the appearance of compressional outer-rise events, such as in Tonga region in the vicinity of 20S, a Mw 8.3 large earthquake occurred in 2006. This result represents that the outer-rise earthquake model could be an indicator for the generation of large earthquakes along subduction zones. In addition, to have a more accurate estimation for the seismic potential, we discuss the relationship between the generation of earthquakes and the change of cumulative gravitational potential energy caused by earthquakes (ΔGPE) over time. Our result shows an acceleration of ΔGPE before large earthquakes. Our result also shows that the extensional outer-rise events for strong seismic coupling subduction zone only presented after the occurrence of earthquakes with magnitude larger than 8, for instance, after the 2012 March Mw 9.0 Tohoku, the 2010 February Mw 8.8 Chili and the 2006 November Mw8.3 Kamchatka earthquakes, which is consistent with the analysis performed by Christensen (1988). Based on our analysis, the outer rise earthquakes occur immediately after the main event which does not coincide with the result stating in Christensen (1988) that they occur in the 30 years after the earthquake. In addition, the duration of the extensional outer-rise earthquakes occurrence appears to be correlated with its magnitude. Meanwhile, for the earthquakes with magnitude smaller than 8, as well as in the weak coupling areas, this observation is not engaged.

  5. Earthquake engineering in Peru

    USGS Publications Warehouse

    Vargas, N.J

    1983-01-01

    During the last decade, earthquake engineering research in Peru has been carried out at the Catholic University of Peru and at the Universidad Nacional de Ingeniera (UNI). The Geophysical Institute (IGP) under the auspices of the Organization of American States (OAS) has initiated in Peru other efforts in regional seismic hazard assessment programs with direct impact to the earthquake engineering program. Further details on these programs have been reported by L. Ocola in the Earthquake Information Bulletin, January-February 1982, vol. 14, no. 1, pp. 33-38. 

  6. Earthquakes and emergence

    NASA Astrophysics Data System (ADS)

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

  7. Global observation of Omori-law decay in the rate of triggered earthquakes

    NASA Astrophysics Data System (ADS)

    Parsons, T.

    2001-12-01

    Triggered earthquakes can be large, damaging, and lethal as evidenced by the 1999 shocks in Turkey and the 2001 events in El Salvador. In this study, earthquakes with M greater than 7.0 from the Harvard CMT catalog are modeled as dislocations to calculate shear stress changes on subsequent earthquake rupture planes near enough to be affected. About 61% of earthquakes that occurred near the main shocks are associated with calculated shear stress increases, while ~39% are associated with shear stress decreases. If earthquakes associated with calculated shear stress increases are interpreted as triggered, then such events make up at least 8% of the CMT catalog. Globally, triggered earthquakes obey an Omori-law rate decay that lasts between ~7-11 years after the main shock. Earthquakes associated with calculated shear stress increases occur at higher rates than background up to 240 km away from the main-shock centroid. Earthquakes triggered by smaller quakes (foreshocks) also obey Omori's law, which is one of the few time-predictable patterns evident in the global occurrence of earthquakes. These observations indicate that earthquake probability calculations which include interactions from previous shocks should incorporate a transient Omori-law decay with time. In addition, a very simple model using the observed global rate change with time and spatial distribution of triggered earthquakes can be applied to immediately assess the likelihood of triggered earthquakes following large events, and can be in place until more sophisticated analyses are conducted.

  8. Influence of Solar Cycles on Earthquakes

    NASA Astrophysics Data System (ADS)

    Tavares, M.

    2011-12-01

    This research inspects possible influence of solar cycles on earthquakes through of statistical analyses. We also discussed the mechanism that would drive the occurrence of increasing of earthquakes during solar maxima. The study was based on worldwide earthquakes events during approximately four hundred years (1600-2010). The increase of earthquakes events followed the Maxima of Solar cycle, and also depends on the tectonic plate location. From 1600 until 1645 events increased during the Maxima in some of the tectonic plates as Pacific, Arabian and South America. The earthquakes analyzed during two grand solar minima, the Maunder (1645-1720) and the Dalton (1790-1820) showed a decrease in the number of earthquakes and the solar activity. It was observed during these minima a significant number of events at specific geological features. After the last minima (Dalton) the earthquakes pattern increased with solar maxima. The calculations showed that events increasing during solar maxima most in the Pacific, South America or Arabian until 1900. Since there were few records during these three centuries we needed additional analysis on modern data. We took the last four solar cycles events (1950-2010) and made similar calculations. The results agreed with the former calculations. It might be that the mechanism for the Sun-Earth connection relies on the solar wind speed. In both records (1600-1900) and (1950-2010) the results showed a significant increase in earthquakes events in some of the tectonic plates linked to solar maxima. The Solar wind energy striking the Earth's magnetosphere affects the entire environment because the pressure on the region increases and the magnetosphere shrinks sometimes four Earth's radii. This sudden compression causes earthquakes in specific plates. During the times of solar minima the pressure from the solar wind on the earth decreases, then the magnetosphere expands and earthquakes happen in a different pattern according to the geological feature on earth's surface less frequently. Solar driven events include coronal mass ejections (CME) and coronal holes, which are at a maximum during the descending phase of solar activity. The tectonic are important because there is heterogeneity in the crust and the tectonic stress depends on each region. The geo-effectiveness of solar wind from a coronal hole only depends on the position of the hole relative to the Earth and for the CMEs an additional factor is their velocity. The influence of these solar events could be detected from electromagnetic variations on the ground prior the earthquakes. The goal in this research was to show the solar events influenced the earthquakes and seismologic events following some special display and also how the Sun's activity played to make earthquakes increase. This paper discussed details of this mechanism, calculations and associated factors.

  9. Correlation of groundwater radon anomalies with earthquakes in the greater Palmdale bulge area

    SciTech Connect

    Teng, T.; Sun, L.; McRaney, J.K.

    1981-05-01

    Recent measurements in the Central Transverse Ranges of southern California suggest possible correlations of changes in groundwater radon content with occurences of nearby earthquakes. Since measurements began in 1974, three radon anomalies have been accompanied by subsequent nearby seismic events. Two of these anomalies were associated with moderate-sized earthquakes and one with a swarm. Within a 60-day window prior to the seismicity, groundwater radon increased in each case at sites close to the earthquake epicenters. Before the Big Bear earthquake of June 30, 1979 (M = 4.8), radon anomalies were found at three nearby monitoring sites. Groundwater radon content at one site near the January 1, 1979 Malibu earthquake (M = 5.0) showed negative as well as positive anomalies both prior to and following the earthquake. A radon anomaly occurred at a nearby spring prior to the fall 1976 Palmdale swarm. The observed pattern is similar to pre-earthquake anomalies reported from Russia, China, and Japan.

  10. Combining historical and geomorphological information to investigate earthquake induced landslides

    NASA Astrophysics Data System (ADS)

    Cardinali, M.; Ferrari, G.; Galli, M.; Guidoboni, E.; Guzzetti, F.

    2003-04-01

    Landslides are caused by many different triggers, including earthquakes. In Italy, a detailed new generation catalogue of information on historical earthquakes for the period 461 B.C to 1997 is available (Catalogue of Strong Italian Earthquakes from 461 B.C. to 1997, ING-SGA 2000). The catalogue lists 548 earthquakes and provides information on a total of about 450 mass-movements triggered by 118 seismic events. The information on earthquake-induced landslides listed in the catalogue was obtained through the careful scrutiny of historical documents and chronicles, but was rarely checked in the field. We report on an attempt to combine the available historical information on landslides caused by earthquakes with standard geomorphological techniques, including the interpretation of aerial photographs and field surveys, to better determine the location, type and distribution of seismically induced historical slope failures. We present four examples in the Central Apennines. The first example describes a rock slide triggered by the 1279 April 30 Umbria-Marche Apennines earthquake (Io = IX) at Serravalle, along the Chienti River (Central Italy). The landslide is the oldest known earthquake-induced slope failure in Italy. The second example describes the location of 2 large landslides triggered by the 1584 September 10 earthquake (Io = IX) at San Piero in Bagno, along the Savio River (Northern Italy). The landslides were subsequently largely modified by mass movements occurred on 1855 making the recognition of the original seismically induced failures difficult, if not impossible. In the third example we present the geographical distribution of the available information on landslide events triggered by 8 earthquakes in Central Valnerina, in the period 1703 to 1979. A comparison with the location of landslides triggered by the September-October 1997 Umbria-Marche earthquake sequence is presented. The fourth example describes the geographical distribution of the available information on landslides triggered by the great 1915 January 13 Marsica (Central Italy) earthquake (Io = XI) mostly along the Liri River valley. Problems encountered in matching the recent historical information with the local geomorphological setting are discussed. A critical analysis of the four studied examples allows general considerations on the advantages and limitations of a combined historical and geomorphological approach to investigate past earthquake induced landslides. Lastly, a preliminary analysis of the relationship between the earthquake intensity and the distance of the known slope failures to the triggering earthquake epicentres is presented, for the four investigated areas and for the entire catalogue of historical earthquakes.

  11. Interseismic deformation for normal fault earthquakes

    NASA Technical Reports Server (NTRS)

    Reilinger, Robert

    1987-01-01

    Comparison between the coseismic vertical deformation associated with normal fault earthquakes and permanent deformation indicated by geologic structure indicates that large deformation must occur during the period between earthquakes. When sufficient geodetic and geologic information is available it is possible to estimate the spatial character of this interseismic deformation. A case in point is the 1983 Borah Peak, Idaho earthquake. This normal fault earthquake produced roughly 5 times as much basin subsidence as it did uplift of the adjacent mountain ranges. In contrast, geophysical and geological observations show that the basin is roughly as deep as the bounding range is high. A similar normal fault event in the Basin and Range, the 1959 Hebgen Lake earthquake, was also accompanied by substantially larger subsidence than uplift. In this case, postseismic geodetic measurements show broad regional uplift with a spatial pattern which is roughly consistent with that proposed for the Borah Peak event. Modeling suggests that postseismic viscoelastic relaxation and strain accumulation in an elastic lithosphere overlying a viscoelastic asthenosphere are possible physical mechanisms to generate interseismic uplift. These mechanisms may be the contemporary expression of those processes responsible for the high elevation of the Basin and Range Province.

  12. Extending the ISC-GEM Global Earthquake Instrumental Catalogue

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  13. Northridge, CA Earthquake Damage

    The person in this image was a USGS employee at the time this was taken. Collection of USGS still images taken after the January 17, 1994 Northridge earthquake highlighting the damage to buildings and infrastructure....

  14. Earthquake history of Vermont

    USGS Publications Warehouse

    von Hake, C. A.

    1977-01-01

    Seven earthquakes of intensity V or greater on the Modified Mercalli Scale (MM) are known to have originated within Vermont. Many additional shocks centered in other New England States and Canada have been strongly felt in Vermont. 

  15. To capture an earthquake

    SciTech Connect

    Ellsworth, W.L. )

    1990-11-01

    An earthquake model based on the theory of plate tectonics is presented. It is assumed that the plates behave elastically in response to slow, steady motions and the strains concentrate within the boundary zone between the plates. When the accumulated stresses exceed the bearing capacity of the rocks, the rocks break, producing an earthquake and releasing the accumulated stresses. As the steady movement of the plates continues, strain begins to reaccumulate. The cycle of strain accumulation and release is modeled using the motion of a block, pulled across a rough surface by a spring. A model earthquake can be predicted by taking into account a precursory event or the peak spring force prior to slip as measured in previous cycles. The model can be applied to faults, e.g., the San Andreas fault, if the past earthquake history of the fault and the rate of strain accumulation are known.

  16. Nonlinear processes in earthquakes

    SciTech Connect

    Jones, E.M.; Frohlich, C.

    1998-12-31

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). Three-dimensional, elastic-wave-propagation calculations were performed to define the effects of near-source geologic structure on the degree to which seismic signals produced by earthquakes resemble {open_quotes}non-double-couple{close_quotes} sources. Signals from sources embedded in a subducting slab showed significant phase and amplitude differences compared with a {open_quotes}no-slab{close_quotes} case. Modifications to the LANL elastic-wave propagation code enabled improved simulations of path effects on earthquake and explosion signals. These simulations demonstrate that near-source, shallow, low-velocity basins can introduce earthquake-like features into explosion signatures through conversion of compressive (P-wave) energy to shear (S- and R-wave) modes. Earthquake sources simulated to date do not show significant modifications.

  17. On the origin of electrotelluric disturbances prior to an earthquake in Kalamata, Greece

    NASA Astrophysics Data System (ADS)

    Gershenzon, N.; Gokhberg, M.

    1993-08-01

    A long distance (200 km) electromagnetic signal occured at Keratea (near Athens), few days prior to the September 13th 1986, Kalamata earthquake. We suggest an explanation based on the fact that long range stress occuring before an earthquake should create local electrical potential gradients in heterogeneous ground at great distances. This could be a general explanation for the origin of electrical telluric signals appearing before an earthquake.

  18. Regular intervals between Hawaiian earthquakes: implications for predicting the next event

    SciTech Connect

    Wyss, M.

    1986-11-07

    During the years 1941 through 1983 five earthquake mainshocks of moderate magnitude occurred at regular intervals of 10.5 +/- 1.5 years within a 6-kilometer radius in Hawaii. It is proposed that these Kaoiki earthquakes will continue to occur at regular intervals because the strain accumulation rate and the strained volume remain constant. With appropriate instrumentation, it may be possible to refine predictions of subsequent Kaoiki earthquakes.

  19. The deep resistivity variation during water loading and unloading and induced earthquake in the Longtan reservoir, Guangxi Province,China

    NASA Astrophysics Data System (ADS)

    Zhan, Y.; Wang, L.; Wang, J.; Qiao, Q.

    2011-12-01

    Longtan reservoir is located in the northwest of Guangxi province in South China. The reservoir began to store water since 2006. Now the current generation has been completed. As the reservoir water level rise, earthquakes frequently happened, and the distribution of these earthquakes is concentrated in four clustering areas. In order to understand the relationship between reservoir earthquakes and reservoir water level change. Five times of magnetotelluric measurements were carried out during loading and unloading of the Longtan reservoir from 2009 to 2010. The surveys were conducted at 4 sites (Jiaobitun,Pingshang,Zhongliangping and Xiangyang sites)with a frequency band of 320Hz-1000s and The 4 sites were located in an earthquake clustering areas. Moreover along the two NW-trending Profiles, 34 MT sites had measured and the two MT profiles across the main reservoir earthquake-prone areas. Combined with the regional deep electrical structure, the analysis of measurements of the reservoir suggests that the five measured apparent resistivity values at the three sites Pingshang, Zhongliangping and Xiangyang, which bear same lithology, were roughly the same, with the minimum at the low frequency band less than 1 Hz when the water level of the reservoir was the highest. While the measured apparent resistivity values at the Jiaobitun site of distinct lithology was different from the other three sites, and did not change considerably during loading and unloading of the reservoir. It implies that the seepage behaviors of reservoir water depend on lithology and deep electric structure. When the lithology and deep electric structure are largely consistent, the water seepage is primarily controlled by the gravity weight of reservoir water. Among the sources of 4 earthquake clustering areas, three are located in the lower portion of the Permian(P1) and Carboniferous(C) strata with low resistivity, attributed to the induced events associated with water in karsts. The seismic event with the maximum magnitude occurred within the lower part of high-resistivity body, of which the width tapers downward. It is speculated that the earthquakes in this reservoir can be attributed to strain accumulation in the high-resistivity body due to the increase of water pressure after water storage and the water permeation. This study indicates that electromagnetic method can be utilized to study processes of reservoir water loading and unloading and water filtration, and the type, mechanism and setting of reservoir induced earthquakes. This research was supported by the "Eleventh Five-Year" national scientific and technological support projects (2008BAC38B033).

  20. Periodic slow slip triggers megathrust zone earthquakes in northeastern Japan

    NASA Astrophysics Data System (ADS)

    Uchida, Naoki; Iinuma, Takeshi; Nadeau, Robert M.; Bürgmann, Roland; Hino, Ryota

    2016-01-01

    Both aseismic and seismic slip accommodate relative motion across partially coupled plate-boundary faults. In northeastern Japan, aseismic slip occurs in the form of decelerating afterslip after large interplate earthquakes and as relatively steady slip on uncoupled areas of the subduction thrust. Here we report on a previously unrecognized quasi-periodic slow-slip behavior that is widespread in the megathrust zone. The repeat intervals of the slow slip range from 1 to 6 years and often coincide with or precede clusters of large [magnitude (M) ≥ 5] earthquakes, including the 2011 M 9 Tohoku-oki earthquake. These results suggest that inherently periodic slow-slip events result in periodic stress perturbations and modulate the occurrence time of larger earthquakes. The periodicity in the slow-slip rate has the potential to help refine time-dependent earthquake forecasts.

  1. Oklahoma’s recent earthquakes and saltwater disposal

    PubMed Central

    Walsh, F. Rall; Zoback, Mark D.

    2015-01-01

    Over the past 5 years, parts of Oklahoma have experienced marked increases in the number of small- to moderate-sized earthquakes. In three study areas that encompass the vast majority of the recent seismicity, we show that the increases in seismicity follow 5- to 10-fold increases in the rates of saltwater disposal. Adjacent areas where there has been relatively little saltwater disposal have had comparatively few recent earthquakes. In the areas of seismic activity, the saltwater disposal principally comes from “produced” water, saline pore water that is coproduced with oil and then injected into deeper sedimentary formations. These formations appear to be in hydraulic communication with potentially active faults in crystalline basement, where nearly all the earthquakes are occurring. Although most of the recent earthquakes have posed little danger to the public, the possibility of triggering damaging earthquakes on potentially active basement faults cannot be discounted. PMID:26601200

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

    PubMed Central

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

    2014-01-01

    When an earthquake occurs, seismologists want to use recorded seismograms to infer its location, magnitude and source-focal mechanism as quickly as possible. If such information could be determined immediately, timely evacuations and emergency actions could be undertaken to mitigate earthquake damage. Current advanced methods can report the initial location and magnitude of an earthquake within a few seconds, but estimating the source-focal mechanism may require minutes to hours. Here we present an earthquake search engine, similar to a web search engine, that we developed by applying a computer fast search method to a large seismogram database to find waveforms that best fit the input data. Our method is several thousand times faster than an exact search. For an Mw 5.9 earthquake on 8 March 2012 in Xinjiang, China, the search engine can infer the earthquake’s parameters in <1 s after receiving the long-period surface wave data. PMID:25472861

  3. An appraisal of aftershocks behavior for large earthquakes in Persia

    NASA Astrophysics Data System (ADS)

    Nemati, Majid

    2014-01-01

    This study focuses on the distribution of aftershocks in both location and magnitude for recent earthquakes in Iran. 43 Earthquakes are investigated, using data from the global International Seismological Center (ISC) seismic catalogue and from the regional earthquake catalogue of the Institute of Geophysics, University of Tehran (IGUT) between 1961-2006 and 2006-2012 respectively. We only consider the earthquakes with magnitude greater than 5.0. The majority of these events are intracontinental, occurring over four seismotectonic provinces across Iran. Processing aftershock sequences reported by both catalogues with cut-off magnitude of 2.5 and a sequence duration of 70 days, leads us to define a spatial horizontal area (A) occupied with the aftershocks as a function of mainshock magnitude (M) for Persian earthquakes: ISC: Log10(A) = 0.45MS + 0.23; IGUT: Log10(A) = 0.25MN + 1.7.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  5. Periodic slow slip triggers megathrust zone earthquakes in northeastern Japan.

    PubMed

    Uchida, Naoki; Iinuma, Takeshi; Nadeau, Robert M; Bürgmann, Roland; Hino, Ryota

    2016-01-29

    Both aseismic and seismic slip accommodate relative motion across partially coupled plate-boundary faults. In northeastern Japan, aseismic slip occurs in the form of decelerating afterslip after large interplate earthquakes and as relatively steady slip on uncoupled areas of the subduction thrust. Here we report on a previously unrecognized quasi-periodic slow-slip behavior that is widespread in the megathrust zone. The repeat intervals of the slow slip range from 1 to 6 years and often coincide with or precede clusters of large [magnitude (M) ≥ 5] earthquakes, including the 2011 M 9 Tohoku-oki earthquake. These results suggest that inherently periodic slow-slip events result in periodic stress perturbations and modulate the occurrence time of larger earthquakes. The periodicity in the slow-slip rate has the potential to help refine time-dependent earthquake forecasts. PMID:26823425

  6. Precise measurements help gauge Pacific Northwest's Earthquake potential

    NASA Astrophysics Data System (ADS)

    Miller, M. Meghan; Dragert, Herb; Endo, Elliot; Freymueller, Jeffrey T.; Goldfinger, Chris; Kelsey, Harvey M.; Humphreys, Eugene D.; Johnson, Daniel J.; McCaffrey, Robert; Oldow, John S.; Qamar, Anthony; Rubin, Charles M.

    Except for the recent rumblings of a few moderate earthquakes and the eruption of Mt. St. Helen's, all has been relatively quiet on the Pacific Northwestern front. The Cascades region in the Pacific Northwest, a sporadically active earthquake and volcanic zone, still has great seismic potential [Atwater, 1987], as comparisons with other subduction zones around the world have shown [Heaton and Kanamori, 1984]. Recent tsunami propagation models [Satake, 1996] and tree ring studies suggest that the last great Cascadia earthquake occurred in the winter of 1700 A.D. and had a magnitude of -8.9. The North Cascades or Wenatchee earthquake followed in 1872. With an estimated magnitude greater than 7, it was the largest earthquake in the written history of Washington and Oregon.

  7. Earthquake education in California

    USGS Publications Warehouse

    MacCabe, M. P.

    1980-01-01

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

  8. Head Lice: Treatment Frequently Asked Questions (FAQs)

    MedlinePlus

    ... Treatment FAQs Malathion FAQs Epidemiology & Risk Factors Disease Biology Diagnosis Treatment Prevention & Control Resources for Health Professionals ... Frequently Asked Questions (FAQs) Epidemiology & Risk Factors Disease Biology Diagnosis Treatment Prevention & Control Resources for Health Professionals ...

  9. Dengue/Severe Dengue Frequently Asked Questions

    MedlinePlus

    ... Feed Youtube Twitter Facebook Google + iTunes Play Store Dengue control Menu Dengue Control strategies Monitoring and evaluation Other arbo-viral diseases Research Information resources Dengue/Severe dengue frequently asked questions What is dengue ...

  10. Women and Diabetes: Frequently Asked Questions

    MedlinePlus

    ... A A A Listen En Español Women and Diabetes: Frequently Asked Questions Why are women with diabetes ... 05-book-italian-diabetes-cookbook.html More from diabetes.org Learn More: Behind the Drive - 2016-05- ...

  11. Simulating Earthquake Early Warning Systems in the Classroom as a New Approach to Teaching Earthquakes

    NASA Astrophysics Data System (ADS)

    D'Alessio, M. A.

    2010-12-01

    A discussion of P- and S-waves seems an ubiquitous part of studying earthquakes in the classroom. Textbooks from middle school through university level typically define the differences between the waves and illustrate the sense of motion. While many students successfully memorize the differences between wave types (often utilizing the first letter as a memory aide), textbooks rarely give tangible examples of how the two waves would "feel" to a person sitting on the ground. One reason for introducing the wave types is to explain how to calculate earthquake epicenters using seismograms and travel time charts -- very abstract representations of earthquakes. Even when the skill is mastered using paper-and-pencil activities or one of the excellent online interactive versions, locating an epicenter simply does not excite many of our students because it evokes little emotional impact, even in students located in earthquake-prone areas. Despite these limitations, huge numbers of students are mandated to complete the task. At the K-12 level, California requires that all students be able to locate earthquake epicenters in Grade 6; in New York, the skill is a required part of the Regent's Examination. Recent innovations in earthquake early warning systems around the globe give us the opportunity to address the same content standard, but with substantially more emotional impact on students. I outline a lesson about earthquakes focused on earthquake early warning systems. The introductory activities include video clips of actual earthquakes and emphasize the differences between the way P- and S-waves feel when they arrive (P arrives first, but is weaker). I include an introduction to the principle behind earthquake early warning (including a summary of possible uses of a few seconds warning about strong shaking) and show examples from Japan. Students go outdoors to simulate P-waves, S-waves, and occupants of two different cities who are talking to one another on cell phones. The culminating activity is for students to "design" an early warning system that will protect their school from nearby earthquakes. The better they design the system, the safer they will be. Each team of students receives a map of faults in the area and possible sites for real-time seismometer installation. Given a fixed budget, they must select the best sites for detecting a likely earthquake. After selecting their locations, teams face-off two-by-two in a tournament of simulated earthquakes. We created animations of a few simulated earthquakes for our institution and have plans to build a web-based version that will allow others to customize the location to their own location and facilitate the competition between teams. Earthquake early warning is both cutting-edge and has huge societal benefits. Instead of teaching our students how to locate epicenters after an earthquake has occurred, we can teach the same content standards while showing them that earthquake science can really save lives.

  12. Response of a 14-story Anchorage, Alaska, building in 2002 to two close earthquakes and two distant Denali fault earthquakes

    USGS Publications Warehouse

    Celebi, M.

    2004-01-01

    The recorded responses of an Anchorage, Alaska, building during four significant earthquakes that occurred in 2002 are studied. Two earthquakes, including the 3 November 2002 M7.9 Denali fault earthquake, with epicenters approximately 275 km from the building, generated long trains of long-period (>1 s) surface waves. The other two smaller earthquakes occurred at subcrustal depths practically beneath Anchorage and produced higher frequency motions. These two pairs of earthquakes have different impacts on the response of the building. Higher modes are more pronounced in the building response during the smaller nearby events. The building responses indicate that the close-coupling of translational and torsional modes causes a significant beating effect. It is also possible that there is some resonance occurring due to the site frequency being close to the structural frequency. Identification of dynamic characteristics and behavior of buildings can provide important lessons for future earthquake-resistant designs and retrofit of existing buildings. ?? 2004, Earthquake Engineering Research Institute.

  13. Potentially induced earthquakes in Oklahoma, USA: links between wastewater injection and the 2011 Mw 5.7 earthquake sequence

    USGS Publications Warehouse

    Keranen, Katie M.; Savage, Heather M.; Abers, Geoffrey A.; Cochran, Elizabeth S.

    2013-01-01

    Significant earthquakes are increasingly occurring within the continental interior of the United States, including five of moment magnitude (Mw) ≥ 5.0 in 2011 alone. Concurrently, the volume of fluid injected into the subsurface related to the production of unconventional resources continues to rise. Here we identify the largest earthquake potentially related to injection, an Mw 5.7 earthquake in November 2011 in Oklahoma. The earthquake was felt in at least 17 states and caused damage in the epicentral region. It occurred in a sequence, with 2 earthquakes of Mw 5.0 and a prolific sequence of aftershocks. We use the aftershocks to illuminate the faults that ruptured in the sequence, and show that the tip of the initial rupture plane is within ~200 m of active injection wells and within ~1 km of the surface; 30% of early aftershocks occur within the sedimentary section. Subsurface data indicate that fluid was injected into effectively sealed compartments, and we interpret that a net fluid volume increase after 18 yr of injection lowered effective stress on reservoir-bounding faults. Significantly, this case indicates that decades-long lags between the commencement of fluid injection and the onset of induced earthquakes are possible, and modifies our common criteria for fluid-induced events. The progressive rupture of three fault planes in this sequence suggests that stress changes from the initial rupture triggered the successive earthquakes, including one larger than the first.

  14. Injection-induced earthquakes

    USGS Publications Warehouse

    Ellsworth, William L.

    2013-01-01

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

  15. Injection-induced earthquakes.

    PubMed

    Ellsworth, William L

    2013-07-12

    Earthquakes in unusual locations have become an important topic of discussion in both North America and Europe, owing to the concern that industrial activity could cause damaging earthquakes. It has long been understood that earthquakes can be induced by impoundment of reservoirs, surface and underground mining, withdrawal of fluids and gas from the subsurface, and injection of fluids into underground formations. Injection-induced earthquakes have, in particular, become a focus of discussion as the application of hydraulic fracturing to tight shale formations is enabling the production of oil and gas from previously unproductive formations. Earthquakes can be induced as part of the process to stimulate the production from tight shale formations, or by disposal of wastewater associated with stimulation and production. Here, I review recent seismic activity that may be associated with industrial activity, with a focus on the disposal of wastewater by injection in deep wells; assess the scientific understanding of induced earthquakes; and discuss the key scientific challenges to be met for assessing this hazard. PMID:23846903

  16. Simulating Earthquakes for Science and Society: New Earthquake Visualizations Ideal for Use in Science Communication

    NASA Astrophysics Data System (ADS)

    de Groot, R. M.; Benthien, M. L.

    2006-12-01

    The Southern California Earthquake Center (SCEC) has been developing groundbreaking computer modeling capabilities for studying earthquakes. These visualizations were initially shared within the scientific community but have recently have gained visibility via television news coverage in Southern California. These types of visualizations are becoming pervasive in the teaching and learning of concepts related to earth science. Computers have opened up a whole new world for scientists working with large data sets, and students can benefit from the same opportunities (Libarkin &Brick, 2002). Earthquakes are ideal candidates for visualization products: they cannot be predicted, are completed in a matter of seconds, occur deep in the earth, and the time between events can be on a geologic time scale. For example, the southern part of the San Andreas fault has not seen a major earthquake since about 1690, setting the stage for an earthquake as large as magnitude 7.7 -- the "big one." Since no one has experienced such an earthquake, visualizations can help people understand the scale of such an event. Accordingly, SCEC has developed a revolutionary simulation of this earthquake, with breathtaking visualizations that are now being distributed. According to Gordin and Pea (1995), theoretically visualization should make science accessible, provide means for authentic inquiry, and lay the groundwork to understand and critique scientific issues. This presentation will discuss how the new SCEC visualizations and other earthquake imagery achieve these results, how they fit within the context of major themes and study areas in science communication, and how the efficacy of these tools can be improved.

  17. Fundamental questions of earthquake statistics, source behavior, and the estimation of earthquake probabilities from possible foreshocks

    USGS Publications Warehouse

    Michael, Andrew J.

    2012-01-01

    Estimates of the probability that an ML 4.8 earthquake, which occurred near the southern end of the San Andreas fault on 24 March 2009, would be followed by an M 7 mainshock over the following three days vary from 0.0009 using a Gutenberg–Richter model of aftershock statistics (Reasenberg and Jones, 1989) to 0.04 using a statistical model of foreshock behavior and long‐term estimates of large earthquake probabilities, including characteristic earthquakes (Agnew and Jones, 1991). I demonstrate that the disparity between the existing approaches depends on whether or not they conform to Gutenberg–Richter behavior. While Gutenberg–Richter behavior is well established over large regions, it could be violated on individual faults if they have characteristic earthquakes or over small areas if the spatial distribution of large‐event nucleations is disproportional to the rate of smaller events. I develop a new form of the aftershock model that includes characteristic behavior and combines the features of both models. This new model and the older foreshock model yield the same results when given the same inputs, but the new model has the advantage of producing probabilities for events of all magnitudes, rather than just for events larger than the initial one. Compared with the aftershock model, the new model has the advantage of taking into account long‐term earthquake probability models. Using consistent parameters, the probability of an M 7 mainshock on the southernmost San Andreas fault is 0.0001 for three days from long‐term models and the clustering probabilities following the ML 4.8 event are 0.00035 for a Gutenberg–Richter distribution and 0.013 for a characteristic‐earthquake magnitude–frequency distribution. Our decisions about the existence of characteristic earthquakes and how large earthquakes nucleate have a first‐order effect on the probabilities obtained from short‐term clustering models for these large events.

  18. Hidden Markov Modeling of Waiting Times in the 1985 Yellowstone Earthquake Swarm

    NASA Astrophysics Data System (ADS)

    Li, Yumei; Anderson-Sprecher, Richard

    2013-05-01

    Earthquake swarms occur in many regions of the world. The study of earthquake swarms is very limited, and most contributions are descriptive. In this paper we propose use of a hidden Markov model to estimate the distribution of waiting times for swarm earthquakes and apply this approach to the largest earthquake swarm in the history of the Yellowstone area. Hidden Markov modeling is superior to modeling using either single distributions or finite mixture distributions because of the heterogeneity of data and temporal dependencies in earthquake sequences.

  19. Polar motion, atmospheric angular momentum excitation and earthquakes - Correlations and significance

    NASA Technical Reports Server (NTRS)

    Preisig, Joseph R.

    1992-01-01

    Equatorial atmospheric angular momentum (AAM) excitation functions and polar motion excitation functions (derived by Kalman filtering Very Long Baseline Interferometry polar motion estimates) are compared with the times of 1984-mid-1988 large earthquakes (magnitude greater than or equal to 7.5). There is a moderate correlation between times of large earthquakes and peaks in polar motion excitation. A strong correlation exists between the times of large earthquakes and large peaks in equatorial AAM amplitude; such a correlation is evident for six out of the eight large earthquakes occurring over the studied time interval. The AAM results indicate potential for the temporal prediction of large/great earthquakes.

  20. Predicting earthquakes along the major plate tectonic boundaries in the Pacific

    USGS Publications Warehouse

    Spall, H.

    1978-01-01

    In an article in the last issue of the Earthquake Information Bulletin ("Earthquakes and Plate Tectonics," by Henry Spall), we saw how 90 percent of the world's earthquakes occur at the margins of the Earth's major crustal plates. however, when we look at the distribution of earthquakes in detail, we see that a number of nearly aseismic regions, or seismic gaps, can be found along the present-day plate boundaries. Why is this? And can we regard these areas as being more likely to be the sites for future larger earthquakes than those segments of the plate boundaries that have ruptured recently. 

  1. Slow earthquakes associated with fault healing on a serpentinized plate interface

    PubMed Central

    Katayama, Ikuo; Iwata, Mutsumi; Okazaki, Keishi; Hirauchi, Ken-ichi

    2013-01-01

    Slow earthquakes that occur at subduction zones are distinct from regular earthquakes in terms of their slip behavior. We consider this difference to relate to localized hydration reactions at the plate interface that influence the frictional properties. The results of laboratory friction experiments indicate that simulated serpentine faults are characterized by a low healing rate and large slip-weakening distance compared with unaltered dry fault patches. These results are consistent with the slip mechanism of slow earthquakes, indicating that a locally serpentinized plate interface could trigger slow earthquakes, assisted by pore pressure build-up, whereas unaltered dry patches that remain strongly coupled are potential sites of regular earthquakes.

  2. A primer to frequent itemset mining for bioinformatics

    PubMed Central

    Naulaerts, Stefan; Meysman, Pieter; Bittremieux, Wout; Vu, Trung Nghia; Vanden Berghe, Wim; Goethals, Bart

    2015-01-01

    Over the past two decades, pattern mining techniques have become an integral part of many bioinformatics solutions. Frequent itemset mining is a popular group of pattern mining techniques designed to identify elements that frequently co-occur. An archetypical example is the identification of products that often end up together in the same shopping basket in supermarket transactions. A number of algorithms have been developed to address variations of this computationally non-trivial problem. Frequent itemset mining techniques are able to efficiently capture the characteristics of (complex) data and succinctly summarize it. Owing to these and other interesting properties, these techniques have proven their value in biological data analysis. Nevertheless, information about the bioinformatics applications of these techniques remains scattered. In this primer, we introduce frequent itemset mining and their derived association rules for life scientists. We give an overview of various algorithms, and illustrate how they can be used in several real-life bioinformatics application domains. We end with a discussion of the future potential and open challenges for frequent itemset mining in the life sciences. PMID:24162173

  3. A primer to frequent itemset mining for bioinformatics.

    PubMed

    Naulaerts, Stefan; Meysman, Pieter; Bittremieux, Wout; Vu, Trung Nghia; Vanden Berghe, Wim; Goethals, Bart; Laukens, Kris

    2015-03-01

    Over the past two decades, pattern mining techniques have become an integral part of many bioinformatics solutions. Frequent itemset mining is a popular group of pattern mining techniques designed to identify elements that frequently co-occur. An archetypical example is the identification of products that often end up together in the same shopping basket in supermarket transactions. A number of algorithms have been developed to address variations of this computationally non-trivial problem. Frequent itemset mining techniques are able to efficiently capture the characteristics of (complex) data and succinctly summarize it. Owing to these and other interesting properties, these techniques have proven their value in biological data analysis. Nevertheless, information about the bioinformatics applications of these techniques remains scattered. In this primer, we introduce frequent itemset mining and their derived association rules for life scientists. We give an overview of various algorithms, and illustrate how they can be used in several real-life bioinformatics application domains. We end with a discussion of the future potential and open challenges for frequent itemset mining in the life sciences. PMID:24162173

  4. Cluster analysis of earthquake swarms - results from West Bohemia and South-West Iceland

    NASA Astrophysics Data System (ADS)

    Čermáková, Hana; Cesca, Simone; Horálek, Josef

    2015-04-01

    Earthquake swarms are specific type of seismic activity when strain energy is released in numerous mostly shallow earthquakes, which are missing a single large event; instead a few dominant earthquakes reach similar magnitudes so that smaller events are not associated with any identifiable mainshock. Earthquake swarms distinctively cluster in time and space and last from several hours to several months. They occur at boundaries of the lithospheric plates (interplate), within the plates (intraplate), and they are very often related to the volcanic areas, geothermal fields and ocean ridges. In our study we explored the behaviour of earthquake swarms within a tectonic plate, in a boundary of tectonic plates and in volcanic areas in order to understand why the energy is released successively by sequences of small events in contrast to mainshock-aftershock earthquakes. We used catalogue data from West Bohemia-Vogtland region (WB) situated within a tectonic plate, and three different tectonic basis in South-West Iceland (SWI), namely boundary of tectonic plates (Krísuvík), the edge of a zone where typically mainshock-aftershock earthquakes occur (Olfus, South Iceland Sesmic Zone) and the volcanic area (Hengill). In case of WB we analyzed two swarms, 2000 and 2008, which occurred on the same fault segments. We analyzed distribution of events in a view of a spatial metric obtained from relative locations and time metric (in case of WB and SWI), and a focal mechanism metric based on double couple (DC) solutions (in case of WB). For this purpose we used clustering method by Cesca et al. (2014). The results are strongly affected by the subjective choice of two parameters which describe the desired density of points to infer a cluster. For the tested applications, we repeated the clustering several times to decide the best combination of these parameters. The cluster analysis applied to the double-difference locations disclosed several separate clusters in each area investigated which indicates that in all such different tectonic environments the swarms activate a number of smaller fault segments rather than one main fault. The time clustering discovered several separate phases in time which are characterized by abrupt increase of activity in a view of number of events and their magnitude. In case of WB, both 2000 and 2008 swarms show the same pattern. One significant and several smaller clusters appeared by processing of locations. From the analysis based on focal mechanisms we obtained three main mechanisms (oblique-normal, oblique-thrust and thrust faulting). For 2008 we got one additional mechanism appearing on a fault segment which was not activated in 2000 (thrust faulting with different strike). Strikes and dips of the focal mechanisms correspond to geometry of fault segments which are identified by the clustering method applied to the locations. The main fault segment is characterized by the most frequent mechanism (oblique-normal with strike and dip of about 170° and 80°). However, in its northern part, on its edge and sometime even inside the segment focal mechanisms differ significantly. This supports an idea that earthquake swarms occur on short fault segments with heterogeneous stress. References: Cesca S, Sen AT, Dahm T (2014) "Seismicity monitoring by cluster analysis of moment tensors", Geophys. J. Int., 196 (3):1813-1826

  5. Acute Myocardial Infarction and Stress Cardiomyopathy following the Christchurch Earthquakes

    PubMed Central

    Chan, Christina; Elliott, John; Troughton, Richard; Frampton, Christopher; Smyth, David; Crozier, Ian; Bridgman, Paul

    2013-01-01

    Background Christchurch, New Zealand, was struck by 2 major earthquakes at 4:36am on 4 September 2010, magnitude 7.1 and at 12:51pm on 22 February 2011, magnitude 6.3. Both events caused widespread destruction. Christchurch Hospital was the region's only acute care hospital. It remained functional following both earthquakes. We were able to examine the effects of the 2 earthquakes on acute cardiac presentations. Methods Patients admitted under Cardiology in Christchurch Hospital 3 week prior to and 5 weeks following both earthquakes were analysed, with corresponding control periods in September 2009 and February 2010. Patients were categorised based on diagnosis: ST elevation myocardial infarction, Non ST elevation myocardial infarction, stress cardiomyopathy, unstable angina, stable angina, non cardiac chest pain, arrhythmia and others. Results There was a significant increase in overall admissions (p<0.003), ST elevation myocardial infarction (p<0.016), and non cardiac chest pain (p<0.022) in the first 2 weeks following the early morning September earthquake. This pattern was not seen after the early afternoon February earthquake. Instead, there was a very large number of stress cardiomyopathy admissions with 21 cases (95% CI 2.6–6.4) in 4 days. There had been 6 stress cardiomyopathy cases after the first earthquake (95% CI 0.44–2.62). Statistical analysis showed this to be a significant difference between the earthquakes (p<0.05). Conclusion The early morning September earthquake triggered a large increase in ST elevation myocardial infarction and a few stress cardiomyopathy cases. The early afternoon February earthquake caused significantly more stress cardiomyopathy. Two major earthquakes occurring at different times of day differed in their effect on acute cardiac events. PMID:23844213

  6. Statistical distributions of earthquake numbers: consequence of branching process

    NASA Astrophysics Data System (ADS)

    Kagan, Yan Y.

    2010-03-01

    We discuss various statistical distributions of earthquake numbers. Previously, we derived several discrete distributions to describe earthquake numbers for the branching model of earthquake occurrence: these distributions are the Poisson, geometric, logarithmic and the negative binomial (NBD). The theoretical model is the `birth and immigration' population process. The first three distributions above can be considered special cases of the NBD. In particular, a point branching process along the magnitude (or log seismic moment) axis with independent events (immigrants) explains the magnitude/moment-frequency relation and the NBD of earthquake counts in large time/space windows, as well as the dependence of the NBD parameters on the magnitude threshold (magnitude of an earthquake catalogue completeness). We discuss applying these distributions, especially the NBD, to approximate event numbers in earthquake catalogues. There are many different representations of the NBD. Most can be traced either to the Pascal distribution or to the mixture of the Poisson distribution with the gamma law. We discuss advantages and drawbacks of both representations for statistical analysis of earthquake catalogues. We also consider applying the NBD to earthquake forecasts and describe the limits of the application for the given equations. In contrast to the one-parameter Poisson distribution so widely used to describe earthquake occurrence, the NBD has two parameters. The second parameter can be used to characterize clustering or overdispersion of a process. We determine the parameter values and their uncertainties for several local and global catalogues, and their subdivisions in various time intervals, magnitude thresholds, spatial windows, and tectonic categories. The theoretical model of how the clustering parameter depends on the corner (maximum) magnitude can be used to predict future earthquake number distribution in regions where very large earthquakes have not yet occurred.

  7. Analysis of Landslides Triggered by October 2005, Kashmir Earthquake

    PubMed Central

    Mahmood, Irfan; Qureshi, Shahid Nadeem; Tariq, Shahina; Atique, Luqman; Iqbal, Muhammad Farooq

    2015-01-01

    Introduction: The October 2005, Kashmir earthquake main event was triggered along the Balakot-Bagh Fault which runs from Bagh to Balakot, and caused more damages in and around these areas. Major landslides were activated during and after the earthquake inflicting large damages in the area, both in terms of infrastructure and casualties. These landslides were mainly attributed to the minimum threshold of the earthquake, geology of the area, climatologic and geomorphologic conditions, mudflows, widening of the roads without stability assessment, and heavy rainfall after the earthquake. These landslides were mainly rock and debris falls. Hattian Bala rock avalanche was largest landslide associated with the earthquake which completely destroyed a village and blocked the valley creating a lake. Discussion: The present study shows that the fault rupture and fault geometry have direct influence on the distribution of landslides and that along the rupture zone a high frequency band of landslides was triggered. There was an increase in number of landslides due to 2005 earthquake and its aftershocks and that most of earthquakes have occurred along faults, rivers and roads. It is observed that the stability of landslide mass is greatly influenced by amplitude, frequency and duration of earthquake induced ground motion. Most of the slope failures along the roads resulted from the alteration of these slopes during widening of the roads, and seepages during the rainy season immediately after the earthquake. Conclusion: Landslides occurred mostly along weakly cemented and indurated rocks, colluvial sand and cemented soils. It is also worth noting that fissures and ground crack which were induced by main and after shock are still present and they pose a major potential threat for future landslides in case of another earthquake activity or under extreme weather conditions. PMID:26366324

  8. Magnitude 8.1 Earthquake off the Solomon Islands

    NASA Technical Reports Server (NTRS)

    2007-01-01

    On April 1, 2007, a magnitude 8.1 earthquake rattled the Solomon Islands, 2,145 kilometers (1,330 miles) northeast of Brisbane, Australia. Centered less than ten kilometers beneath the Earth's surface, the earthquake displaced enough water in the ocean above to trigger a small tsunami. Though officials were still assessing damage to remote island communities on April 3, Reuters reported that the earthquake and the tsunami killed an estimated 22 people and left as many as 5,409 homeless. The most serious damage occurred on the island of Gizo, northwest of the earthquake epicenter, where the tsunami damaged the hospital, schools, and hundreds of houses, said Reuters. This image, captured by the Landsat-7 satellite, shows the location of the earthquake epicenter in relation to the nearest islands in the Solomon Island group. Gizo is beyond the left edge of the image, but its triangular fringing coral reefs are shown in the upper left corner. Though dense rain forest hides volcanic features from view, the very shape of the islands testifies to the geologic activity of the region. The circular Kolombangara Island is the tip of a dormant volcano, and other circular volcanic peaks are visible in the image. The image also shows that the Solomon Islands run on a northwest-southeast axis parallel to the edge of the Pacific plate, the section of the Earth's crust that carries the Pacific Ocean and its islands. The earthquake occurred along the plate boundary, where the Australia/Woodlark/Solomon Sea plates slide beneath the denser Pacific plate. Friction between the sinking (subducting) plates and the overriding Pacific plate led to the large earthquake on April 1, said the United States Geological Survey (USGS) summary of the earthquake. Large earthquakes are common in the region, though the section of the plate that produced the April 1 earthquake had not caused any quakes of magnitude 7 or larger since the early 20th century, said the USGS.

  9. Postseismic relaxation following the 1994 Mw6.7 Northridge earthquake, southern California

    USGS Publications Warehouse

    Savage, J.C.; Svarc, J.L.

    2010-01-01

    We have reexamined the postearthquake deformation of a 65 km long linear array of 11 geodetic monuments extending north–south across the rupture (reverse slip on a blind thrust dipping 40°S–20°W) associated with the 1994 Mw6.7 Northridge earthquake. That array was surveyed frequently in the interval from 4 to 2650 days after the earthquake. The velocity of each of the monuments over the interval 100–2650 days postearthquake appears to be constant. Moreover, the profile of those velocities along the length of the array is very similar to a preearthquake velocity profile for a nearby, similarly oriented array. We take this to indicate that significant postseismic relaxation is evident only in the first 100 days postseismic and that the subsequent linear trend is typical of the interseismic interval. The postseismic relaxation (postseismic displacement less displacement that would have occurred at the preseismic velocity) is found to be almost wholly parallel (N70°W) to the nearby (40 km) San Andreas Fault with only negligible relaxation in the direction of coseismic slip (N20°E) on the Northridge rupture. We suggest that the N70°W relaxation is caused by aseismic, right-lateral slip at depth on the San Andreas Fault, excess slip presumably triggered by the Northridge rupture. Finally, using the Dieterich (1994) stress-seismicity relation, we show that return to the preseismic deformation rate within 100 days following the earthquake could be consistent with the cumulative number of M > 2.5 earthquakes observed following the main shock.

  10. Information Needs While A Disaster Is Occurring

    NASA Astrophysics Data System (ADS)

    Perry, S. C.

    2010-12-01

    Evidence from recent earthquakes, wildfires, and debris flows in southern California indicates that many people - local officials as well as residents and visitors - lack important understanding during the time that a disaster is unfolding, a time of uncertainty and confusion. While some of the uncertainty is inherent, some could be alleviated. Physical scientists and engineers know what to expect as the event unfolds. Social scientists know how humans will react during a disaster, and how to effectively communicate the warnings or evacuation orders that may precede it. Such knowledge can improve public safety. As just a few of many examples: - Based on questions posed at numerous public talks, many individuals who practice "Drop Cover and Hold" during earthquake drills do not understand what they are protecting themselves against, and thus cannot determine what to do when an earthquake strikes and they have no cover available. Similarly, they do not know how to act during the aftershocks that follow. - The 2009 Station Fire in the San Gabriel Mountains put foothills communities at risk, first from the wildfire and then from debris flows. Some neighborhoods received multiple evacuation notices during a few days or months. Local officials have expressed frustration and concern about an evacuation compliance rate that is steadily dropping and is now below 50%. The debris flow danger will persist over the next 2-4 winters yet evacuation compliance may drop lower still. - On February 6, 2010, a significant rainstorm brought the threat of imminent debris flows to areas burned by the Station Fire. In one neighborhood, residents loaded their cars with important belongings then waited for indications that they should evacuate. Powerful debris flows suddenly appeared, sweeping the cars downhill and destroying both cars and belongings. Some residents did understand that rainfall intensity would control the generation of debris flows in that storm. But they didn't understand that rainfall intensity at their homes might be less than the intensity up in the mountains where the debris flows would start. Nor did they know that debris flows travel too quickly to be outrun. These and many other examples indicate need for social and natural scientists to increase awareness of what to expect when the disaster strikes. This information must be solidly understood before the event occurs - while a disaster is unfolding there are no teachable moments. Case studies indicate that even those who come into a disaster well educated about the phenomenon can struggle to apply what they know when the real situation is at hand. In addition, psychological studies confirm diminished ability to comprehend information at times of stress.

  11. Effect of frequent ejaculation on semen characteristics in rams.

    PubMed

    Jennings, J J; McWeeney, J

    1976-03-20

    Sixteen Suffolk rams were ejaculated repeatedly for a period of eight hours during the month of November. Ejaculates were examined for semen characteristics. Volume density and number of sperm per ejaculate declined significantly in successive ejaculates. Motility and percentage abnormal sperm were not affected by frequent collection. It is concluded that the number of sperm per ejaculate, after the eighth ejaculate, could fall below that required for fertilisation to occur, particularly in progestagen treated ewes. PMID:1265983

  12. Rock friction and its implications for earthquake prediction examined via models of Parkfield earthquakes.

    PubMed Central

    Tullis, T E

    1996-01-01

    The friction of rocks in the laboratory is a function of time, velocity of sliding, and displacement. Although the processes responsible for these dependencies are unknown, constitutive equations have been developed that do a reasonable job of describing the laboratory behavior. These constitutive laws have been used to create a model of earthquakes at Parkfield, CA, by using boundary conditions appropriate for the section of the fault that slips in magnitude 6 earthquakes every 20-30 years. The behavior of this model prior to the earthquakes is investigated to determine whether or not the model earthquakes could be predicted in the real world by using realistic instruments and instrument locations. Premonitory slip does occur in the model, but it is relatively restricted in time and space and detecting it from the surface may be difficult. The magnitude of the strain rate at the earth's surface due to this accelerating slip seems lower than the detectability limit of instruments in the presence of earth noise. Although not specifically modeled, microseismicity related to the accelerating creep and to creep events in the model should be detectable. In fact the logarithm of the moment rate on the hypocentral cell of the fault due to slip increases linearly with minus the logarithm of the time to the earthquake. This could conceivably be used to determine when the earthquake was going to occur. An unresolved question is whether this pattern of accelerating slip could be recognized from the microseismicity, given the discrete nature of seismic events. Nevertheless, the model results suggest that the most likely solution to earthquake prediction is to look for a pattern of acceleration in microseismicity and thereby identify the microearthquakes as foreshocks. Images Fig. 4 Fig. 4 Fig. 5 Fig. 7 PMID:11607668

  13. Inland Normal Faulting during the Mw 6.6 Iwaki Earthquake Induced By Temporal Change of Stress State after the Mw 9.0 2011 Tohoku Earthquake, Japan

    NASA Astrophysics Data System (ADS)

    Miyakawa, A.; Otsubo, M.

    2014-12-01

    A Mw 6.6 earthquake hit Iwaki area, northeastern Honshu arc, Japan on April 11, 2011 (here 2011 Iwaki earthquake). The 2011 Iwaki earthquake occurred one month after the 2011 Mw 9.0 earthquake off the Pacific coast of Tohoku (March 11, 2011; hereafter, 2011 Tohoku earthquake) (Ozawa et al., 2011; Simons et al., 2011). The 2011 Iwaki earthquake was followed by simultaneous slips of multi faults (the Itozawa fault and the Yunodake fault) (e.g. Toda and Tsutsumi, 2013). We examine the activity of the Itozawa fault and Yunodake fault and the mechanical preparation of the 2011 Iwaki earthquake from the temporal change of the stress state before and after the 2011 Tohoku earthquake. Furthermore, we quantitatively evaluate the role of crustal fluid beneath the faults and its supply mechanisms when the 2011 Iwaki earthquake occurred. We revealed that the generation of the slip on the Itozawa fault and simultaneous activity of faults cannot be occurred under the state of stress before the 2011 Tohoku earthquake, even though the both the state of stress is normal-faulting stress regimes before and after 2011 Tohoku earthquake. We show the importance of excess fluid pressure on the 2011 Iwaki earthquake, and we estimated the magnitude of excess fluid pressure ~30 MPa and ~20 MPa on the Itozawa and Yunodake fault respectively. We also show that the state of stress after the 2011 Tohoku earthquake favorably change the permeability of the Itozawa fault to be supplied the crustal fluid beneath the fault. A part of this research project has been conducted as the regulatory supporting research funded by the Secretariat of Nuclear Regulation Authority (Secretariat of NRA), Japan.

  14. Earthquake-induced water-level fluctuations at Yucca Mountain, Nevada, June 1992

    SciTech Connect

    O`Brien, G.M.

    1993-07-01

    This report presents earthquake-induced water-level and fluid-pressure data for wells in the Yucca Mountain area, Nevada, during June 1992. Three earthquakes occurred which caused significant water-level and fluid-pressure responses in wells. Wells USW H-5 and USW H-6 are continuously monitored to detect short-term responses caused by earthquakes. Two wells, monitored hourly, had significant, longer-term responses in water level following the earthquakes. On June 28, 1992, a 7.5-magnitude earthquake occurred near Landers, California causing an estimated maximum water-level change of 90 centimeters in well USW H-5. Three hours later a 6.6-magnitude earthquake occurred near Big Bear Lake, California; the maximum water-level fluctuation was 20 centimeters in well USW H-5. A 5.6-magnitude earthquake occurred at Little Skull Mountain, Nevada, on June 29, approximately 23 kilometers from Yucca Mountain. The maximum estimated short-term water-level fluctuation from the Little Skull Mountain earthquake was 40 centimeters in well USW H-5. The water level in well UE-25p {number_sign}1, monitored hourly, decreased approximately 50 centimeters over 3 days following the Little Skull Mountain earthquake. The water level in UE-25p {number_sign}1 returned to pre-earthquake levels in approximately 6 months. The water level in the lower interval of well USW H-3 increased 28 centimeters following the Little Skull Mountain earthquake. The Landers and Little Skull Mountain earthquakes caused responses in 17 intervals of 14 hourly monitored wells, however, most responses were small and of short duration. For several days following the major earthquakes, many smaller magnitude aftershocks occurred causing measurable responses in the continuously monitored wells.

  15. The 1909 Taipei earthquake: implication for seismic hazard in Taipei

    USGS Publications Warehouse

    Kanamori, Hiroo; Lee, William H.K.; Ma, Kuo-Fong

    2012-01-01

    The 1909 April 14 Taiwan earthquake caused significant damage in Taipei. Most of the information on this earthquake available until now is from the written reports on its macro-seismic effects and from seismic station bulletins. In view of the importance of this event for assessing the shaking hazard in the present-day Taipei, we collected historical seismograms and station bulletins of this event and investigated them in conjunction with other seismological data. We compared the observed seismograms with those from recent earthquakes in similar tectonic environments to characterize the 1909 earthquake. Despite the inevitably large uncertainties associated with old data, we conclude that the 1909 Taipei earthquake is a relatively deep (50–100 km) intraplate earthquake that occurred within the subducting Philippine Sea Plate beneath Taipei with an estimated M_W of 7 ± 0.3. Some intraplate events elsewhere in the world are enriched in high-frequency energy and the resulting ground motions can be very strong. Thus, despite its relatively large depth and a moderately large magnitude, it would be prudent to review the safety of the existing structures in Taipei against large intraplate earthquakes like the 1909 Taipei earthquake.

  16. Present, Past, Future - What earthquake clusters can tell us about an upcoming Marmara Sea earthquake

    NASA Astrophysics Data System (ADS)

    Schaefer, Andreas; Daniell, James; Wenzel, Friedemann

    2015-04-01

    Earthquake clusters are a worldwide observation, especially with respect to large events in terms of their respective aftershock sequences. These clusters contain a lot of information about the general seismicity of the region and follow various magnitude and location-dependent characteristics. Using the seismic record of smaller magnitudes in the aftermath of large earthquakes, these details can be used to extrapolate these characteristics and to simulate the unrecorded cluster activity of historic earthquakes. The Marmara Sea is prone to frequent strong seismicity, most recently experienced by the destructive Izmit earthquake in 1999 and several historic events with frequent return periods of only a few centuries. For the future, such an event is expected in the area of Istanbul. The city has already experienced several earthquakes over its long history, such as in 1509, when major parts of Constantinople were destroyed or severely damaged. The fault system in the Marmara Sea is very complex, but based on the distribution of fault ruptures during the last 500 years, a seismic gap is visible and experts around the world see an increased probability of a strong earthquake in the vicinity of Istanbul for the next decades. The seismicity and characteristics of clusters around the Marmara Sea and along the North Anatolian fault have been studied. The activity of these clusters, recorded during the last decades, is used to model the spatial and temporal distribution of aftershocks of historic events. In addition, a fault model is used and combined with the results of the cluster analysis to elongate the synthetic earthquake locations to active tectonics. The results are correlated and calibrated with the observed macroseismic intensity distribution of each historic event. With respect to recent ruptures, several scenarios are modelled for future events including and compared in terms of their respective ground accelerations. As a result, a new collection of possible ground acceleration maps is presented and an expectation for the magnitude-dependent aftershock activity which is based on a correlation and extrapolation of earthquake clusters around the Marmara Sea. This type of scenario building approach provides a more detailed basis for risk assessment and management planning with a more realistic scenario providing better analysis and socioeconomic effect study potential in the next disaster.

  17. Earthquake scenarios based on lessons from the past

    NASA Astrophysics Data System (ADS)

    Solakov, Dimcho; Simeonova, Stella; Aleksandrova, Irena; Popova, Iliana

    2010-05-01

    Earthquakes are the most deadly of the natural disasters affecting the human environment; indeed catastrophic earthquakes have marked the whole human history. Global seismic hazard and vulnerability to earthquakes are increasing steadily as urbanization and development occupy more areas that are prone to effects of strong earthquakes. Additionally, the uncontrolled growth of mega cities in highly seismic areas around the world is often associated with the construction of seismically unsafe buildings and infrastructures, and undertaken with an insufficient knowledge of the regional seismicity peculiarities and seismic hazard. The assessment of seismic hazard and generation of earthquake scenarios is the first link in the prevention chain and the first step in the evaluation of the seismic risk. The implementation of the earthquake scenarios into the policies for seismic risk reduction will allow focusing on the prevention of earthquake effects rather than on intervention following the disasters. The territory of Bulgaria (situated in the eastern part of the Balkan Peninsula) represents a typical example of high seismic risk area. Over the centuries, Bulgaria has experienced strong earthquakes. At the beginning of the 20-the century (from 1901 to 1928) five earthquakes with magnitude larger than or equal to MS=7.0 occurred in Bulgaria. However, no such large earthquakes occurred in Bulgaria since 1928, which may induce non-professionals to underestimate the earthquake risk. The 1986 earthquake of magnitude MS=5.7 occurred in the central northern Bulgaria (near the town of Strazhitsa) is the strongest quake after 1928. Moreover, the seismicity of the neighboring countries, like Greece, Turkey, former Yugoslavia and Romania (especially Vrancea-Romania intermediate earthquakes), influences the seismic hazard in Bulgaria. In the present study deterministic scenarios (expressed in seismic intensity) for two Bulgarian cities (Rouse and Plovdiv) are presented. The work on scenarios was guided by the perception that usable and realistic (also in the sense of being compatible with seismic histories of cities that are several centuries long) ground motion maps had to be produced for urban areas. By deterministic scenario it is mean a representation of the severity of ground shaking over an urban area, using one or more hazard descriptors. Such representation can be obtained: - either from the assumption of a "reference earthquake" specified by a magnitude or an epicentral intensity, associated to a particular earthquake source - or, directly, showing values of local macroseimic intensity generated by a damaging, real earthquakes of the past. In the study we chose for the second method using the values of macroseimic intensity caused by damaging historical earthquakes (the 1928 quakes in southern Bulgaria; the 1940 and the 1977 Vrancea intermediate earthquakes) - lessons from the past. Such scenarios are intended as a basic input for developing detailed earthquake damage scenarios for the cities and can be used in earthquake-safe town and infrastructure planning.

  18. Relationship Between Afterslip of 2003 Tokachi Earthquakes and Coseismic-slip of 2004 Kushiro Earthquakes Using Viscoelastic Media

    NASA Astrophysics Data System (ADS)

    Sato, T.; Takemura, H.

    2010-12-01

    The studies of afterslip distribution of large plate interface earthquakes are important for revealing frictional properties on faults, and investigating trigger processes to adjacent faults. After 2003 Tokachi Earthquake (M8.0), Hokkaido, Japan, post seismic deformation was observed, and this observation indicates occurrence of afterslip at eastern side of the earthquake. After 1.2 yr of the Tokachi Earthquake, two large events (M7.1, M6.9) occurred at off Kushiro, which is located 150km east from the Tokachi Earthquake. It is considered that these two events may be triggered by the afterslip of the Tokachi Earthquake. To investigate the trigger process, we estimate special and temporal afterslip distribution. The effect of viscoelastic relaxation at the asthenosphere is important on post seismic surface deformation (Matsu’ura and Sato, GJI, 1989; Sato and Matsu’ura, GJI, 1992). We estimate afterslip distribution of large interplate earthquakes using viscoelastic media. We consider not only viscoelastic responses of coseismic slip but also viscoelastic responses of afterslips (Sato and Higuchi, AGU Fall Meeting, 2009). Because many studies suggested that the magnitude of afterslips was comparable to that of coseismic slip, viscoelastic responses of afterslips should not be negligible. Therefore, surface displacement data include viscoelastic response of coseismic slip, viscoelastic response of afterslips which occurred just after coseismic period to just before the present, and elastic response of the present afterslip. We estimate afterslip distribution of the Tokachi Earthquake using GPS data by GSI, Japan. We use CAMP model (Hashimoto et al, PAGEOPH, 2004) as a plate interface between the Pacific plate and the North American plate. The viscoelastic results show that afterslips concentrate deeper parts of the plate interface at the eastern adjoining area of the Tokachi Earthquake. Just before the Kushiro Events (1-1.2 yr after the Tokachi Earthquake), afterslips distribute at deeper and eastern parts of the Kushiro Events.

  19. The Mw 7.7 Bhuj earthquake: Global lessons for earthquake hazard in intra-plate regions

    USGS Publications Warehouse

    Schweig, E.; Gomberg, J.; Petersen, M.; Ellis, M.; Bodin, P.; Mayrose, L.; Rastogi, B.K.

    2003-01-01

    The Mw 7.7 Bhuj earthquake occurred in the Kachchh District of the State of Gujarat, India on 26 January 2001, and was one of the most damaging intraplate earthquakes ever recorded. This earthquake is in many ways similar to the three great New Madrid earthquakes that occurred in the central United States in 1811-1812, An Indo-US team is studying the similarities and differences of these sequences in order to learn lessons for earthquake hazard in intraplate regions. Herein we present some preliminary conclusions from that study. Both the Kutch and New Madrid regions have rift type geotectonic setting. In both regions the strain rates are of the order of 10-9/yr and attenuation of seismic waves as inferred from observations of intensity and liquefaction are low. These strain rates predict recurrence intervals for Bhuj or New Madrid sized earthquakes of several thousand years or more. In contrast, intervals estimated from paleoseismic studies and from other independent data are significantly shorter, probably hundreds of years. All these observations together may suggest that earthquakes relax high ambient stresses that are locally concentrated by rheologic heterogeneities, rather than loading by plate-tectonic forces. The latter model generally underlies basic assumptions made in earthquake hazard assessment, that the long-term average rate of energy released by earthquakes is determined by the tectonic loading rate, which thus implies an inherent average periodicity of earthquake occurrence. Interpreting the observations in terms of the former model therefore may require re-examining the basic assumptions of hazard assessment.

  20. Afterslip, tremor, and the Denali fault earthquake

    USGS Publications Warehouse

    Gomberg, Joan; Prejean, Stephanie; Ruppert, Natalia

    2012-01-01

    We tested the hypothesis that afterslip should be accompanied by tremor using observations of seismic and aseismic deformation surrounding the 2002 M 7.9 Denali fault, Alaska, earthquake (DFE). Afterslip happens more frequently than spontaneous slow slip and has been observed in a wider range of tectonic environments, and thus the existence or absence of tremor accompanying afterslip may provide new clues about tremor generation. We also searched for precursory tremor, as a proxy for posited accelerating slip leading to rupture. Our search yielded no tremor during the five days prior to the DFE or in several intervals in the three months after. This negative result and an array of other observations all may be explained by rupture penetrating below the presumed locked zone into the frictional transition zone. While not unique, such an explanation corroborates previous models of megathrust and transform earthquake ruptures that extend well into the transition zone.

  1. Hayward fault: Large earthquakes versus surface creep

    USGS Publications Warehouse

    Lienkaemper, James J.; Borchardt, Glenn

    1992-01-01

    The Hayward fault, thought a likely source of large earthquakes in the next few decades, has generated two large historic earthquakes (about magnitude 7), one in 1836 and another in 1868. We know little about the 1836 event, but the 1868 event had a surface rupture extending 41 km along the southern Hayward fault. Right-lateral surface slip occurred in 1868, but was not well measured. Witness accounts suggest coseismic right slip and afterslip of under a meter. We measured the spatial variation of the historic creep rate along the Hayward fault, deriving rates mainly from surveys of offset cultural features, (curbs, fences, and buildings). Creep occurs along at least 69 km of the fault's 82-km length (13 km is underwater). Creep rate seems nearly constant over many decades with short-term variations. The creep rate mostly ranges from 3.5 to 6.5 mm/yr, varying systemically along strike. The fastest creep is along a 4-km section near the south end. Here creep has been about 9mm/yr since 1921, and possibly since the 1868 event as indicated by offset railroad track rebuilt in 1869. This 9mm/yr slip rate may approach the long-term or deep slip rate related to the strain buildup that produces large earthquakes, a hypothesis supported by geoloic studies (Lienkaemper and Borchardt, 1992). If so, the potential for slip in large earthquakes which originate below the surficial creeping zone, may now be 1/1m along the southern (1868) segment and ≥1.4m along the northern (1836?) segment. Substracting surface creep rates from a long-term slip rate of 9mm/yr gives present potential for surface slip in large earthquakes of up to 0.8m. Our earthquake potential model which accounts for historic creep rate, microseismicity distribution, and geodetic data, suggests that enough strain may now be available for large magnitude earthquakes (magnitude 6.8 in the northern (1836?) segment, 6.7 in the southern (1868) segment, and 7.0 for both). Thus despite surficial creep, the fault may be ready for the recurrence of large earthquakes today. However, the timing (Williams, 1992) and size of future events may vary greatly due to uncertainties in the tectonophysical model assumed for the Hayward fault within the greater San Andreas fault system (Lisowski and Savage, 1992).

  2. Baseflow as the trigger of intraplate earthquakes

    NASA Astrophysics Data System (ADS)

    Costain, J. K.

    2012-12-01

    Intraplate earthquakes can be triggered by small changes in crustal loading, unloading, or pore-fluid pressure. A self-organized crust appears to be remarkably sensitive to extremely small changes in either pore-fluid pressure diffusion or stress loading, implying that these small changes in stress do not cause earthquakes, but only trigger them. Baseflow is commonly assumed to be equivalent to recharge. Groundwater recharge can trigger seismicity by reducing the effective normal stress on fractures. Intervals of higher groundwater recharge can be identified by determining when a stream is in baseflow recession, which is accccomplished by a hydrograph separation. Using the central Virginia seismic zone as an example, intraplate earthquakes tend to follow intervals of higher baseflow, i.e., recharge. A finite element model (FEM) of pore-fluid pressure diffusion for which the diffusion is within intersecting and hydraulically transmissive fracture zones allows comparisons to be made between 1) times of maxima in baseflow as determined for stream gaging station 02.0350.00 on the James River in the central Virginia seismic zone (CVSZ) and the time of occurrence of the Virginia 5.8 earthquake of August 23, 2010, and between 2) theoretical times of maxima in pore-fluid pressure diffusion from impulsive surface sources applied to exposed fracture zones as computed from the FEM simulation. The CVSZ, the New Madrid seismic zone, and the central Oklahoma seismic zone (COSZ) are all bisected by major river systems. Preliminary analysis of the stream gaging stations on rivers in and near the COSZ suggests that the earthquakes may be associated with the Canadian River system. The Meers fault does not seem to be involved. There is a slight correlation between the duration of baseflow and earthquake magnitude in the COSZ. The magnitude 5.6 earthquake of November 5, 2011 occurred about 200 days after a prolonged period of relatively high baseflow (recharge) as determined at stream gaging station 07.2410.00. Results to date are consistent with the assumptions of "hydroseismicity", which attributes intraplate seismicity to the dynamics of the hydrologic cycle, and supports the suggestion of Costain and Bollinger (2010) that virtually all naturally-occurring earthquakes fall into just one of two categories: 1) those associated with the dynamics of plate tectonics, or 2) those associated with the dynamics of the hydrologic cycle.

  3. Data mining of atmospheric parameters associated with coastal earthquakes

    NASA Astrophysics Data System (ADS)

    Cervone, Guido

    Earthquakes are natural hazards that pose a serious threat to society and the environment. A single earthquake can claim thousands of lives, cause damages for billions of dollars, destroy natural landmarks and render large territories uninhabitable. Studying earthquakes and the processes that govern their occurrence, is of fundamental importance to protect lives, properties and the environment. Recent studies have shown that anomalous changes in land, ocean and atmospheric parameters occur prior to earthquakes. The present dissertation introduces an innovative methodology and its implementation to identify anomalous changes in atmospheric parameters associated with large coastal earthquakes. Possible geophysical mechanisms are discussed in view of the close interaction between the lithosphere, the hydrosphere and the atmosphere. The proposed methodology is a multi strategy data mining approach which combines wavelet transformations, evolutionary algorithms, and statistical analysis of atmospheric data to analyze possible precursory signals. One dimensional wavelet transformations and statistical tests are employed to identify significant singularities in the data, which may correspond to anomalous peaks due to the earthquake preparatory processes. Evolutionary algorithms and other localized search strategies are used to analyze the spatial and temporal continuity of the anomalies detected over a large area (about 2000 km2), to discriminate signals that are most likely associated with earthquakes from those due to other, mostly atmospheric, phenomena. Only statistically significant singularities occurring within a very short time of each other, and which tract a rigorous geometrical path related to the geological properties of the epicentral area, are considered to be associated with a seismic event. A program called CQuake was developed to implement and validate the proposed methodology. CQuake is a fully automated, real time semi-operational system, developed to study precursory signals associated with earthquakes. CQuake can be used for the retrospective analysis of past earthquakes, and for detecting early warning information about impending events. Using CQuake more than 300 earthquakes have been analyzed. In the case of coastal earthquakes with magnitude larger than 5.0, prominent anomalies are found up to two weeks prior to the main event. In case of earthquakes occurring away from the coast, no strong anomaly is detected. The identified anomalies provide a potentially reliable mean to mitigate earthquake risks in the future, and can be used to develop a fully operational forecasting system.

  4. A probabilistic approach for the classification of earthquakes as `triggered' or `not triggered'. Application to the 13th Jan 1976 Kpasker Earthquake on the Tjrnes Fracture Zone, Iceland

    NASA Astrophysics Data System (ADS)

    Passarelli, Luigi; Maccaferri, Francesco; Rivalta, Eleonora; Dahm, Torsten; Abebe Boku, Elias

    2013-01-01

    The occurrence time of earthquakes can be anticipated or delayed by external phenomena that induce strain energy changes on the faults. `Anticipated' earthquakes are generally called `triggered'; however, it can be controversial to label a specific earthquake as such, mostly because of the stochastic nature of earthquake occurrence and of the large uncertainties usually associated to stress modelling. Here we introduce a combined statistical and physical approach to quantify the probability that a given earthquake was triggered by a given stress-inducing phenomenon. As an example, we consider an earthquake that was likely triggered by a natural event: the M = 6.2 13 Jan 1976 Kpasker earthquake on the Grmsey lineament (Tjrnes Fracture Zone, Iceland), which occurred about 3 weeks after a large dike injection in the nearby Krafla fissure swarm. By using Coulomb stress calculations and the rate-and-state earthquake nucleation theory, we calculate the likelihood of the earthquake in a scenario that contains only the tectonic background and excludes the dike and in a scenario that includes the dike but excludes the background. Applying the Bayes' theorem, we obtain that the probability that the earthquake was indeed triggered by the dike, rather than purely due to the accumulation of tectonic strain, is about 60 to 90 %. This methodology allows us to assign quantitative probabilities to different scenarios and can help in classifying earthquakes as triggered or not triggered by natural or human-induced changes of stress in the crust.

  5. Earthquake processes and hazard along the Sunda megathrust: evaluating evidence for inter-plate coupling anomalies and characteristic earthquakes from the seismic catalogue

    NASA Astrophysics Data System (ADS)

    Bell, A. F.; Greenhough, J.; Naylor, M.; Main, I. G.; McCloskey, J.

    2008-12-01

    Five Mw>7.5 earthquakes have occurred along the Sunda megathrust since the Mw9.2 Sumatra -- Andaman Islands earthquake on the 26th December 2004. Understanding the processes controlling the recurrence of these events is vital for quantifying earthquake hazard in the region. Sea level changes evident in coral growth records have been used to reconstruct a record of great earthquakes on the Sunda megathrust for the last 300 years. The extents of these ruptures appear to coincide with present day inter- plate coupling anomalies, an observation that has been presented as evidence for temporally persistent fault segmentation and recurrent "characteristic" earthquakes. If this hypothesis were shown to be correct, there would be significant implications for earthquake recurrence time, and hence earthquake and tsunami hazard along the coast of Sumatra. Here, we evaluate the evidence for both inter-plate coupling anomalies and characteristic earthquakes contained within more than 30 years of recorded earthquakes along the Sumatran arc. Specifically, we analyze the spatial, temporal and magnitude-frequency (MF) distributions of earthquakes from the NEIC PDE and Harvard CMT catalogues. We determine the spatial correlation between inter-plate coupling coefficients derived from GPS measurements, purportedly describing locked and creeping fault segments, and the occurrence of M>5 earthquakes. We also construct MF distributions accounting for the inherent uncertainties resulting from finite sample effects.

  6. Reducing the Risks of Nonstructural Earthquake Damage: A Practical Guide. Earthquake Hazards Reduction Series 1.

    ERIC Educational Resources Information Center

    Reitherman, Robert

    The purpose of this booklet is to provide practical information to owners, operators, and occupants of office and commercial buildings on the vulnerabilities posed by earthquake damage to nonstructural items and the means available to deal with these potential problems. Examples of dangerous nonstructural damages that have occurred in past…

  7. Micro-Seismicity and Large Earthquake nucleation in Marmara Sea Region

    NASA Astrophysics Data System (ADS)

    Schmittbuhl, J.; Bouchon, M.; Karabulut, H.; Aktar, M.; Özalaybay, S.; Lengliné, O.; Durand, V.; Bouin, M. P.

    2012-04-01

    The existence or observation of a detectable nucleation phase before earthquakes is a longstanding goal with implications for earthquake prediction and risk assessment. While it is well established that some earthquakes are preceded by foreshocks, nothing so far distinguishes these foreshocks from regular earthquake occurrences, so there is no objective way to identify these events as foreshocks until they are followed by a larger earthquake. However, foreshocks are still the most common precursory phenomenon to large earthquakes. On the other hand laboratory and theoretical models of earthquake nucleation predict that slip instability should occur before earthquakes. A key question is then to know how aseismic slip during large earthquake nucleation is related to foreshock sequences and to check if this link is observable. To address this question, we study the nucleation of one of the best recorded large earthquakes to date, the 1999 Mw 7.6 Izmit (Turkey) earthquake, was preceded by a seismic signal of long duration which originated from the hypocenter. The signal consisted of a succession of repetitive seismic bursts, accelerating wi