A Method Of Map Compilation For Expected Earthquakes On Complex Of Seismological Precursors

Résumé: Intensive for earthquake precursors that had started in the sixties made it possible in geophysics at present to accumulate the date on some dozens of precusors phenomena. The efficiency of each percursor determined as a ratio of the average earthquake density in alarm time to the average earthquake density in observation time, as a rule, slightly exceeds the efficiency of the prediction at chance guessing existing prediction experience shows, that the complexity of different precursors for the estimation of the prediction situation increases the prediction efficiency in several time. This paper deals with one of the approaches of the complex analysis of earthquakes precursors with an energy class K> 12.5 that has been developed since 1984. The following seven parameters were used as precursory features seismogenic fault density, b-value small earthquakes number per time unit as a seismic quiescence and activity, t, / tp ratio, emitted seismic energy E and E2'3, each having physical sense. The approch is based on bayesov s principal of determination of spatial-time regions of the high probability to expect strong earthquakes using the complex parameters. All prediction features were presented as the maps with' spatial-time distributions of anomaly variations relatively corresponding background level and had retrospective statistic values of prediction efficiency. Preliminary investigated territory was differentiated according to fault tectonics and results of geodesic measurements. Efficiency estimation of the expected earthquakes map for the Caucasus for the time interval 1981-1985 has shown that it was 2-3 times higher than on separate precursory parameters. Taparavanskoe 13 may 1986 earthquake with magnitude M=5.5 happened in the area which was estimated as a dangerous on the map.

Publié dans la revue: Bulletin du Service Géologique de l'Algérie