PROBABILISTIC SEISMIC HAZARD ANALYSIS OF QUETTA PAKISTAN

Pakistan is a seismically prone country and its provincial capital city Quetta is bordered by a number of faults. Traditionally Peak Ground Acceleration (PGA) is calculated, and is further used in design calculations for structures. However, PGA alone does not amply define the seismic load and modern building code emphasis on use of spectral acceleration values. Seismic hazard analysis has been carried out for Quetta city and design parameters required by codes to define seismic loading have been derived. The maps are developed for 0.2 second (Ss) and 1.0 second spectral acceleration (S_1) values for 2% probability of exceedance in 50 years, equivalent to 2500 years of return period. The proposed maps have been recommended to be included in Building Code of Pakistan.