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本文使用P波初动资料求得1976年5月29日两次龙陵主震及5级以上强余震的震源机制解,并根据体波频谱测定了两主震的断层尺度、破裂速度、地震矩、平均位错、应力降等震源参数。结果表明,该区在近南北向压力作用下,第一主震是北西走向的右旋逆断层,第二主震是北东走向的左旋逆断层;断层尺度小、地震矩小、应力降低是第一主震的重要特征,显示出该震具有很高的初始破裂应力和终止残余应力。这个高的残余应力是继发第二主震的重要原因。
In this paper, the focal mechanism solutions of the two Longling mainshock and the strong aftershocks above M5 on May 29, 1976 were obtained by using the P wave initial data. The fault scales, rupture velocities, earthquakes Moment, average dislocation, stress drop and other source parameters. The results show that the first main shock is the NW trending right-lateral thrust and the second is the northeast trending L-trending thrust under the pressure of nearly north-south direction. The fault has a small scale, a small seismic moment and a stress reduction of The important features of the first main shock show that the earthquake has high initial rupture stress and end residual stress. This high residual stress is an important reason for the second main shock.