Analysis of complex earthquakes and source processes of Longling

In this paper, Kikuchi and Kanamori 's inversion method on the complex body waves was modified to cover the following: the subevents with geometry parameters of an added minor fault can distribute along the strikes of either the major fault or the minor fault; the rupture direction on the fault plane can be arbitrary. This technique was applied to the 29 May 1976, Longling earthquake (the first one). The results show that this event was caused by the activities of a nearly strike-slip major fault with strike 150° and a vertically dip-slip minor fault with the same strike. About 10 sub-events (6 occurred on the major fault and 4 on the minor fault) and the rupture directivity brought about the very complex P waveforms. Compared with its not very large magnitude, Longling earthquake is an unusually complex one.