This dissertation focuses on using dynamic rupture models to study earthquake source physics and generate earthquake scenarios for the sake of regional seismic hazard estimation. We use a 3D finite element code MAFE (Ma and Liu, 2006) to study rupture dynamics. This code is capable of incorporating 3D velocity structure, non-planar fault geometry and topographical effect with a linear slip-weakening friction relationship. We also use the UCSB method toolchain in the SCEC BBP platform to calculate broadband ground motion due to an earthquake scenario. Our study of dynamic rupture interpretation of the 2008 Wenchuan earthquake suggested a simple patchy initial stress model could explain the major features observed by seismic inversion techniques, which results complicated local tectonic environment. Our study of the ground motion level due to potential seismic hazard due to Wasatch Fault Salt Lake City (WFSLC) segment indicates the ground motion level should be pretty consistent with the GMPE predictions. In addition, we discussed how the non-trivial fault geometry of WFSLC would affect the ground motion in the earthquake scenarios.