利用成都、昆明遥测数字地震波形记录资料,研究大量小震震源机制解和视应力值,分析了区域应力场动态和视应力值的时-空分布。给出川青地块平均应力场方位的时间变化。川青地块平均主应力场的方位在汶川8.0级地震前出现明显扰动,同时,地块力轴张量的倾角变化也很明显。得出2006～2007年川青块体逆冲型地震比例偏高,汶川8.0级地震前区域中小地震震源错动类型发生变化的结果,与区域地形变的分析结果是一致的。根据地震波形全波段计算辐射能量,求得的视应力σapp值揭示区域视应力值的微动态起伏过程与区域主压应力场方位的转折类似,可用于地块蕴震物理过程的探索。从汶川8.0级地震前的中短期视应力σapp值的空间分布看,震中所在的龙门山断裂带是低应力分布区,而相对高视应力则分布在外围地区。这些图像可能揭示了汶川8.0级地震前中短期发震构造附近呈现的闭锁现象。

This article uses the telemetry digital seismic waveform data from Chengdu and Kunming to study the focal mechanism solutions and the apparent stress values of a large number of small earthquakes, and analyzes the regional stress field dynamics and the spatio-temporal distribution of apparent stress values. The temporal variation of the average stress field azimuth in Sichuan-Qinghai block is given. The average principal stress field azimuth of Sichuan-Qinghai block had obvious disturbances before the Wench...