seismic hazard studies

1. EXECUTIVE SUMMARY
For the Seismic Hazard Studies (SHS) of the Peshawar Bus Rapid Transit (BRT) Corridor
Project, an assessment of regional geological and tectonic information collected from the
existing literature and maps has been carried out. On the basis of available data, the critical
tectonic features affecting the Project region has been identified and Seismic Hazard Studies
(SHS) has been conducted using Probabilistic Seismic Hazard Analysis (PSHA) approach, for
selecting the seismic design parameters of the Project, in accordance with the Building Code
of Pakistan (BCP), Seismic Provisions (2007).
Seismotectonic features in the Peshawar Region are seismically active at moderate to high
level. The historical earthquake data shows that a few damaging earthquakes have occurred
within 200 km radius from the Peshawar. The prominent recent one is the October 08, 2005
Kashmir-Hazara earthquake with magnitude Mw=7.6. Probabilistic Seismic Hazard Analysis
(PSHA) has been carried out using the single site EZ-FRISK software developed by Fugro
Engineering Consultants, USA, keeping in view the guidelines contained in the Building Code
of Pakistan (BCP), Seismic Provisions (2007).
The Project region was divided into seven area seismic source zones based on their
homogeneous tectonic and seismic characteristics. Latest NGA (2008) equations developed
under Pacific Earthquake Engineering Research (PEER) Centre by Abrahamson & Silva,
Boore & Atkinson, and Campbell & Bozorgnia were used.
The Project falls in Zone-2B of Building Code of Pakistan Seismic Provisions (2007). The
seismic range of Zone-2B is from 0.16g to 0.24g. The Building Code of Pakistan Seismic
Provision 2007, specifically places Peshawar in Zone-2B and explicitly defines that “Z” Value
of Zone-2B is 0.20.
The total hazard curve obtained from probabilistic seismic hazard analysis gives a horizontal
Peak Ground Acceleration (PGA) of 0.23g for a return period of 475 years and 0.20g for a
return period of 320 years. For other Soil Profile types, necessary application of the
amplification factors should be used as given in BCP Seismic Provisions (2007).