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Earthquake prediction is a branch of the science of seismology concerned with the specification of the time, location, and magnitude of future earthquakes within stated confidence limits but with sufficient precision that a warning can be issued.〔, following , who in turn followed . says: "This definition has several defects which contribute to confusion and difficulty in prediction research." In addition to specification of time, location, and magnitude, Allen suggested three other requirements: 4) indication of the author's confidence in the prediction, 5) the chance of an earthquake occurring anyway as a random event, and 6) publication in a form that gives failures the same visibility as successes. define prediction (in part) "to be a formal rule where by the available space-time-seismic moment manifold of earthquake occurrence is significantly contracted ...."〕〔, p. 507.〕 Of particular importance is the prediction of hazardous earthquakes likely to cause loss of life or damage to infrastructure. Earthquake prediction is sometimes distinguished from ''earthquake forecasting'', which can be defined as the probabilistic assessment of ''general'' earthquake hazard, including the frequency and magnitude of damaging earthquakes in a given area over years or decades.〔, p. 1205. See also , p. 327.〕 It can be further distinguished from earthquake warning systems, which upon detection of an earthquake, provide a real-time warning to regions that might be affected. In the 1970s, scientists were optimistic that a practical method for predicting earthquakes would soon be found, but by the 1990s continuing failure led many to question whether it was even possible.〔; , §2.3, p. 427; , p. 261.〕 Demonstrably successful predictions of large earthquakes have not occurred and the few claims of success are controversial.〔E.g., the most famous claim of a successful prediction is that alleged for the 1975 Haicheng earthquake , and is now listed as such in textbooks . A later study concluded there was no valid short-term prediction , as described in more detail below.〕 Extensive searches have reported many possible earthquake precursors, but, so far, such precursors have not been reliably identified across significant spatial and temporal scales 〔.〕 While some scientists still hold that, given enough resources, prediction might be possible, many others now maintain that earthquake prediction is inherently impossible.〔; . See also (''Nature'' Debates ).〕 == Evaluating earthquake predictions == Predictions are deemed significant if they can be shown to be successful beyond random chance.〔, p. 32; , p. 302.〕 Therefore, methods of statistical hypothesis testing are used to determine the probability that an earthquake such as is predicted would happen anyway (the null hypothesis). The predictions are then evaluated by testing whether they correlate with actual earthquakes better than the null hypothesis.〔; .〕 In many instances, however, the statistical nature of earthquake occurrence is not simply homogeneous. Clustering occurs in both space and time.〔, p. 3775.〕 In southern California about 6% of M≥3.0 earthquakes are "followed by an earthquake of larger magnitude within 5 days and 10 km."〔.〕 In central Italy 9.5% of M≥3.0 earthquakes are followed by a larger event within 30 km and 48 hours.〔.〕 While such statistics are not satisfactory for purposes of prediction (giving ten to twenty false alarms for each successful prediction) they will skew the results of any analysis that assumes that earthquakes occur randomly in time, for example, as realized from a Poisson process. It has been shown that a "naive" method based solely on clustering can successfully predict about 5% of earthquakes;〔. This was based on data from Southern California.〕 slightly better than chance. As the purpose of short-term prediction is to enable emergency measures to reduce death and destruction, failure to give warning of a major earthquake, that does occur, or at least an adequate evaluation of the hazard, can result in legal liability,〔The manslaughter convictions against the seven scientists and technicians in Italy are not for failing to ''predict'' the L'Aquila earthquake (where some 300 people died) as for ''giving undue assurance'' to the populace – one victim called it "anaesthetizing" – that there would ''not'' be a serious earthquake, and therefore no need to take precautions. ; . Additional details in .〕 or even political purging.〔It has been reported that members of the Chinese Academy of Sciences were purged for "having ignored scientific predictions of the disastrous Tangshan earthquake of summer 1976." .〕 But warning of an earthquake that does not occur also incurs a cost:〔In January 1999 there was a report that China was introducing "tough regulations intended to stamp out ‘false’ earthquake warnings, in order to prevent panic and mass evacuation of cities triggered by forecasts of major tremors." This was prompted by "more than 30 unofficial earthquake warnings ... in the past three years, none of which has been accurate."〕 not only the cost of the emergency measures themselves, but of civil and economic disruption.〔, §5.2, p. 437.〕 False alarms, including alarms that are cancelled, also undermine the credibility, and thereby the effectiveness, of future warnings.〔.〕 The acceptable trade-off between missed quakes and false alarms depends on the societal valuation of these outcomes. The rate of occurrence of both must be considered when evaluating any prediction method.〔 and through out.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「earthquake prediction」の詳細全文を読む スポンサード リンク
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