Estimation of source parameters and depth of focus of the earthquake of Sikkim Himalaya by waveform modelling

Abstract

The earthquake of 19 November 1980, which occurred in the Sikkim Himalaya was investigated by waveform modelling technique. The synthetic seismograms for both the P- and S-waves were generated using wave number integration method. The P- wave seismograms were generated using different velocity models for the source and receiver crusts. The S-wave seismograms were produced using only the half-space model for both the source and receiver crusts. Comparing the seismograms of these waves with the respective seismograms digitally recorded by the Global Digital Seismograph Network the source parameters have been estimated. The orientation parameters determined in this way are strike = 119 °, dip = 74° and dip direction = S29W for one modal plane and strike = 218 °, dip= 64° and dip direction = N52W for the other modal plane. The modal plane striking in NW direction has been preferred as representing the fault plane. The depth of the earthquake has been estimated to be 22 km. The total duration of the rupture process has been estimated to be 7 s.