A Seismic Hazard Map Based on Geology and Shear-wave Velocity in Rawalpindi-Islamabad,Pakistan

• 作者: Sarfraz KHAN Muhammad WASEEM M.Asif KHAN
• 来源期刊: 地质学报（英文版）
• 年，卷（期）: 2021,（2）
• 所属期刊栏目: ORIGINAL ARTICLES
• 页码范围: 659-673
• 页数: 15页
• 语种: 英文

摘要

The'twin cities'district of Rawalpindi-Islamabad is among the most endangered seismic regions in Pakistan,with the seismic hazard assessed(0.32 g)to intensity IX MMI for a 475-year return period.A seismic hazard map for Rawalpindi-Islamabad is presented herein,based on 85 shear-wave velocity(Vs)profiles obtained through geophysical H/V measurements and from the geological map of the region.Relationships between the average top thirty-meter shear-wave velocities(Vs30)and surficial geological units have been determined.The peak ground acceleration(PGA)maps for 150,475 and 2475-year return periods were converted into a seismic intensity map.Intensity increments for different soils were used to compute PGA values for 150,475 and 2475-year return periods.Sites located on softer ground experienced a higher degree of damage from moderate earthquakes.Due to the presence of soft clay or liquefiable soil and lateral spreading,a few locations may be classified as hybrid sites class C and D.This map is a critical step in facilitating code-based site classification and seismic design throughout Rawalpindi-Islamabad.Although the seismic hazard map based on seismic intensities is no longer used in engineering geology,it is still important in seismological analysis and for civil protection purposes.