Moment tensor solutions and 3D wavefield simulation in Garhwal Himalayas

We provide a high-quality moment tensor catalog for Uttarakhand Himalayas. The improvement in moment tensor solution is achieved by using both the body waves and the surface waves for misfit estimation. By applying differential filters for the body waves and the surface wave components we are able to use as much data as possible. This cut-and-paste approach is able to provide accurate solutions even in areas with sparse network coverage. For test events, we estimate the MT solutions using different 1D velocity models and show that shallow crustal model (Mahesh et al., 2013, modHim) on top of the reference ak135 model provides the best results. First, we prepare the greens function library using FK for modHim model and validate our synthetics with those obtained from AxiSem. Then we perform the double couple moment tensor inversion using the python-based moment tensor and uncertainty quantification package, mtuq. The estimated moment tensor solutions are then simulated in a 3D model of Himalayas (Koulakov et al, 2015). The simulation is performed using spectral-element approach. Our simulation also respects topography and Moho discontinuity. In the next phase, we plan on embedding the vs30 model on top, and also include the major basin such as the Dehradun basin. Inclusion of topography and basin model in the simulations will play a crucial role for hazard assessment in Himalayas.