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The inter-event time (IET) is sometimes used as a basis for prediction of large earthquakes. It is the case when theoretical analysis of prediction is possible. Quite recently, a specific IET model was suggested for dynamic probabilistic prediction of \( M \ge 5.5 \) events in Italy (http://earthquake.bo.ingv.it). In this study we analyze some aspects of the statistical estimation of the model and its predictive ability. We find that more or less effective prediction is possible within four out of 34 seismotectonic zones where seismicity rate or clustering of events is relatively high. We show that, in the framework of the model, one can suggest a simple zone-independent strategy, which practically optimizes the relative number of non-accidental successes, or the Hanssen-Kuiper (HK) skill score. This quasi-optimal strategy declares alarm in a zone for the first 2.67 years just after the occurrence of each large event in the zone. The optimal HK skill score values are about 26 % for the three most active zones, and 2–10 % for the 26 least active zones. However, the number of false alarm time intervals per one event in each of the zones is unusually high: about 0.7 and 0.8–0.95, respectively. Both these theoretical estimations are important because any prospective testing of the model is unrealistic in most of the zones during a reasonable time. This particular analysis requires a discussion of the following issues of general interest: a specific approach to the analysis of predictions vs. the standard CSEP testing approach; prediction vs. forecasting; HK skill score vs. probability gain; the total forecast error diagram and connected false alarms. 相似文献
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Following our experience in intermediate-term monitoring of seismicity before large earthquakes worldwide and in some regions we apply a similar approach to the analysis of seismicity on global scale several decades before the December 26, 2004 Sumatra–Andaman mega-earthquake. The Earth lithosphere is being considered as a single whole, representing the ultimate level of the complex Earth's hierarchy. The study brings up the following questions: Are there any anomalies of the global seismicity behaviour observed in advance of the mega-earthquake? Do these anomalies correspond to the global scale seismic patterns similar to those detected on the regional scale before great, major, and strong events? In other words, does the Earth lithosphere considered as a single whole show up an approach of the mega-earthquake in the way typical for events on the smaller levels of hierarchy? The results of our investigation favour the positive answer to the questions. Specifically we found that during the decade before the Sumatra–Andaman mega-earthquake the Earth lithosphere reveals, at least in intermediate-term scale, classical symptoms of instability, which can be depicted by known precursory seismic patterns. These are: (i) transformation of frequency–magnitude distribution, (ii) change in the rate of seismic activity, and (iii) depth redistribution of activity. Moreover changes of dependencies between magnitudes of different types are detected at the same time. The observed global scale patterns of collective behaviour of seismicity may indicate the state of criticality of the Earth lithosphere before the Sumatra–Andaman mega-earthquake. 相似文献
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Analysis of Italian Earthquake catalogs in the context of intermediate-term prediction problem 总被引：1，自引：0，他引：1
We perform a comparative analysis of regional and global earthquake catalogs currently available for the territory of Italy. We consider: (a) instrumental seismic catalogs provided by the Istituto Nazionale di Geofisica e Vulcanologia, Roma (INGV) for earthquake forecasting experiment in Italy within the Collaboratory for the Study of Earthquake Predictability (CSEP); (b) Global Hypocenters’ Data provided by the USGS/NEIC, which is currently used in the real-time earthquake prediction experiment by CN and M8S algorithms in Italy, and (c) seismological Bulletin provided by the International Seismological Centre (ISC). We discuss advantages and shortcomings of these catalogs in the context of intermediate-term middle-range earthquake prediction problem in Italy, including the possibility of the catalog’s combined or integrated use. Magnitude errors in the catalog can distort statistics of success-to-failure scoring and eventually falsify testing results. Therefore, the analysis of systematic and random errors in magnitude presented in Appendixes can be of significance in its own right. 相似文献
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