With a developed extended earthquake source model and modified absorbing boundaries, I plan to model the realistic fault by using the fault geometry and slip history [47] of the 1994 Northridge, CA, earthquake and simulate the 17 January 1994 Northridge (M 6.7) earthquake. The model will be verified by comparing the simulation results with those from other numerical methods and with observed data. Furthermore, analysis of a basin site effects and structural response spectra will be compared to observed damage distribution to reduce earthquakes losses. It is hoped that this will help gain a better understanding of the effects of local site conditions on structural response and damage, and reduce future earthquake losses. This will make my Ph.D dissertation research practical and valuable.