共查询到20条相似文献，搜索用时 890 毫秒
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Roberto Sabadini Riccardo E. M. Riva Giorgio Dalla Via 《Geophysical Journal International》2007,171(1):231-243
Polar motion is modelled for the large 2004 Sumatra earthquake via dislocation theory for an incompressible elastic earth model, where inertia perturbations are due to earthquake-triggered topography of density–contrast interfaces, and for a compressible model, where inertia perturbation due to compression-dilatation of Earth's material is included; density and elastic parameters are based on a multilayered reference Earth. Both models are based on analytical Green's functions, propagated from the centre to the Earth's surface. Preliminary and updated seismological solutions are considered in elucidating the effects of improving earthquake parameters on polar motion. The large Sumatra thrust earthquake was particularly efficient in driving polar motion since it was responsible for large material displacements occurring orthogonally to the strike of the earthquake and to the Earth's surface, as imaged by GRACE gravity anomalies over the earthquake area. The effects of earthquake-induced topography are four times larger than the effects of Earth's compressibility, for l = 2 geopotential components. For varying compressional Earth properties and seismic solution, modelled polar motion ranges from 8.6 to 9.4 cm in amplitude and between 117° and 130° east longitude in direction. The close relationship between polar motion direction, earthquake longitude and thrust nature of the event, are established in terms of basic physical concepts. 相似文献
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Testing alarm-based earthquake predictions 总被引：1，自引：0，他引：1
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A successfully stress-forecast earthquake 总被引：21，自引：0，他引：21
Stuart Crampin Theodora Volti & Ragnar Stefánsson 《Geophysical Journal International》1999,138(1):F1-F5
A M = 5 earthquake in Iceland has been successfully 'stress forecast' by using variations in time delays of seismic shear wave splitting to assess the time and magnitude at which stress-modified microcracking reaches fracture criticality within the stressed volume where strain is released. Local investigations suggested the approximate location of the forecast earthquake. We report the criteria on which this stress forecast was based. 相似文献
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Kailash 《Population geography : a journal of the Association of Population Geographers of India》1996,18(1-2):47-60
"[The] Marathwada earthquake, one of the worst natural calamities in India so far, happened to be a factor in the loss of thousands of human and animal lives and the destruction of a vast stretch of natural environment. In this study an attempt has been made to enlist the quake affected victims and to analyse their demographic characteristics in terms of their distribution at district level." 相似文献
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A geomagnetic precursor to the 1979 Carlisle earthquake 总被引：3，自引：0，他引：3
David Beamish 《Geophysical Journal International》1982,68(2):531-543
Summary. A study of horizontal field transfer functions, in the period range 10–104 s, has been made for the 2 yr period preceding the 1979 Carlisle earthquake (magnitude 5). The study using two sites, local to and remote from the earthquake epicentre, reveals that a precursory effect is observed at short periods (<102 s) some 35 km from the main epicentre. The results indicate a change from two-dimensional geolectric anisotropy to a more conductive three-dimensional geoelectric configuration during the period immediately preceding the earthquake. 相似文献
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Likelihood analysis of earthquake catalogues 总被引：5，自引：0，他引：5
Y. Y. Kagan 《Geophysical Journal International》1991,106(1):135-148
We apply several classes of stochastic multidimensional models to statistical analysis of earthquake catalogues using likelihood methods. We investigate the importance of including different earthquake parameters in the model: epicentral coordinates, hypocentral depth, time limits for interearthquake interaction, and especially spatial distribution of earthquakes as well as spatial aftershock patterns. Results of this study combined with other investigations, suggest that most distributions controlling earthquake interaction have a fractal or scale-invariant form. Developed models are used for statistical analysis of several earthquake catalogues to evaluate parameters of earthquake occurrence. These parameters are shown to be similar for shallow earthquakes of different magnitude ranges and seismogenic regions, confirming self-similarity of the earthquake process. Whereas intermediate earthquakes seem to emulate the pattern of shallow earthquake occurrence, albeit at a much smaller aftershock rate, deep earthquakes differ significantly in their properties. Predictability of standard shallow earthquake catalogues has been analysed; we present evidence that for the best available catalogues the predictability is close to 10 bits per earthquake. Several synthetic earthquake catalogues have been created and processed through the likelihood inversion scheme. The results from likelihood analysis of these catalogues confirm our approach. 相似文献
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Correlations of earthquake focal mechanisms 总被引：1，自引：0，他引：1
Y. Y. Kagan 《Geophysical Journal International》1992,110(2):305-320
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Multifractal analysis of earthquake catalogues 总被引：1，自引：0，他引：1
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Robert A. J. Matthews 《Geophysical Journal International》1997,131(3):526-529
I apply Decision Theory to the question of how accurate earthquake predictions must be to serve as a reliable basis for action. Even with optimistic estimates of the parameters involved, the lower bound on the required accuracy is extraordinarily demanding, being over 10 times higher than that of current meteorological forecasts. Given the abruptly self-organizing nature of earthquakes, it is extremely unlikely that precursors can attain such levels of accuracy. I therefore conclude that prediction of major earthquakes is, in any practical sense, impossible. 相似文献
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Simulated annealing for earthquake location 总被引：1，自引：0，他引：1
Stephen D. Billings 《Geophysical Journal International》1994,118(3):680-692
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Mike Taylor 《New Zealand geographer》2011,67(3):190-198
When events such as the Darfield earthquake take place, it is assumed that the response from the geography teaching community provides the opportunity to reinforce the relevance of geography. This article reports the findings of a questionnaire which seeks to explore the question, ‘What were the characteristics of the learning and teaching of Year 11 Geography teachers in the weeks following the Darfield earthquake, September 4, 2010?’ The data offer empirical support for the agency of geography teachers' impressing the relevance of the subject to school students in response to an extreme natural event under New Zealand's collective backyard. 相似文献
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The IASPEI procedure for the evaluation of earthquake precursors 总被引：4，自引：0，他引：4
Full scientific evaluation of proposed earthquake precursors for earthquake prediction is a problem because independent testing is difficult or impossible. To approach this difficulty, and to assess the current state of the art of earthquake prediction research, IASPEI has devised a peer-review procedure for precursor evaluation. The procedure does not consider predictions of impending earthquakes, but evaluates case histories of proposed precursors for past events according to stated validation criteria, which are specified in terms of guidelines concerning the hypothesized physical model, data quality, anomaly definition, the rules of association of precursor with earthquake, and statistical significance. So far, five precursors have been placed on a preliminary list of significant earthquake precursors, although none has satisfied the validation criteria well enough to ensure that their placement is permanent. Exclusion of a precursor from the list does not mean it is useless, but further work is required if it is to become convincing. The main objectives in producing the list are to establish a consensus on the criteria which a precursor must satisfy to be recognized as validated, and to find case histories which satisfy these criteria. Further nominations of precursor candidates are requested for evaluation by the IASPEI procedure. 相似文献
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The basis for earthquake prediction 总被引：3，自引：0，他引：3
Stuart Crampin 《Geophysical Journal International》1987,91(2):331-347
Summary. Recent advances in understanding the behaviour of shear waves propagating in the crust make the routine prediction of earthquakes seem practicable. Accumulating evidence suggests that most of the Earth's crust is pervaded by distributions of fluid-filled cracks and microcracks that are aligned by the contemporary stress-field so that the cracked rockmass is effectively anisotropic to seismic waves. This causes shear-waves to split, and shear-wave splitting is observed whenever shear-waves propagating along suitable raypaths in the crust are recorded by three-component instruments. These distributions of cracks are known as extensive-dilatancy anisotropy or EDA. Many characteristics of the crack- and stress-geometry can be monitored by analyzing shear-waves propagating through the cracked rockmass. Observations of temporal variations of the behaviour of shear-wave splitting in seismic gaps confirm these hypotheses, and suggest that stress changes before earthquakes may be monitored by analyzing shear-waves. In particular, monitoring earthquake preparation zones with three-component shear-wave vertical-seismic-profiles could lead to techniques for the routine prediction of earthquakes. 相似文献