【摘要】 分析了中国大陆地区1970年以来117次中强地震(东部MS≥5.5, 西部MS≥6.0), 其中有直接前震的地震11次, 占9%; 有广义前震的地震63次, 占51%. 直接前震与主震的时间间隔优势分布在30天以内, 空间距离50 km以内, 震级差在1级以上. 利用辽宁数字地震资料, 得到了1999年11月29日和2000年1月15日岫岩MS5.6和5.1地震前的直接前震具有较高的剪应力背景.更多还原

【Abstract】 In the paper, we analyze 117 moderate strong earthquakes occurred in Chinese mainland ( M S≥5.5 in the east and M S≥6.0 in the west) since 1970, among them, 11 earthquakes (about 9%) have direct foreshocks and 63 earthquakes (about 51%) have generalized foreshocks. The predominant time interval between foreshock and main earthquake is no more than 30 days with a spatial distance less than 50 km and a magnitude difference over 1. From the digital seismic data in Liaoning Province, we know that direct foreshock had an obvious shear stress background before the M S=5.6 and M S=5.1 Xiuyan earthquakes occurred on Nov. 29, 1999 and Jan.15, 2000.更多还原