1983年菏泽5.9级地震前波速比的异常变化

本文收集了山东及河南台网1981年1月至1983年11月临沐、莒县、菏泽、林县,浚县等廿多个台站记录到的一百五十多个地震的资料,研究了1983年11月7日菏泽地震前波速比的异常变化。除用一般统计方法进行处理之外,特别使用了模糊数学方法来识别波速比的前兆异常。本文结果表明,菏泽地震前,即1982年1月至1983年10月波速比出现异常变化,异常区最大线度约220公里;波速比异常的时空特性与我国其它地震基本一致。

HEZE EARTHQUAKE(M=5.9) ANOMALOUS VARIATIONS OF SEISMIC VELOCITY RATIO BEFORE THE 1983

Based on the observational data of more than 150 earthquake recordedby stations of Shandong and Henan networks from January, 1981 toNovember, 1983, the anomalous variations of V_P/V_S before the Hezeearthquake (M=5.9) on November 7, 1983 were studied. Besides the sta-tistical method, a method of fuzzy sets theory was applied to the recogni-tion of precursory anomaly of seismic velocity ratio. The resultsshow that the seismic velocity ratio had anomalous variations in period ofduring January, 1982 to November, 1983 before the Heze earthquake, andthe maximum linear dimension of anomalous region was about 220 km.The temporal and spatial characteristics of V_P/V_S anomaly before thisevent were basically similar to those before other earthquakes in China.