Seismo-tectonics around Lhasa, Tibet

Abstract

In this thesis I have described the seismic-tectonics of the Tibetan Plateau and around Lhasa as well as introduced the basic situation of seismic stations in Tibet. The focal mechanism, seismic moment and the source depth for the 2008 Damxung and 1992 Nyimo events were determined using the teleseismic body-wave inversion method by Kikuchi and Kanamori (1982; 1986; 1991) with their algorithm. Observed waveforms were collected from the Global Seismographic Network (GSN) at teleseismic distance between 30° and 90°. A better focal mechanism solution for both events was obtained with an appropriate velocity model at the source, respectively. Results indicate that both events are normal faulting and the source parameters are similar. According to the result of moment tensor inversion and selected input parameters, the ground motion at the Lhasa station for the 2008 Damxung earthquake was simulated by using the stochastic finite-fault technique based on dynamic corner frequency with the program EXSIM (Motazedian, 2009). The ground-motion data used for comparison was taken from the Global Seismographic Network broadband stations of IRIS-DMC. The simulation result overall agrees with the observed acceleration response spectra.