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 doesnot 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.