An updated and gridded probabilistic seismic hazard assessment of Quetta city, Pakistan using multiple source models

• Published in: Journal of Asian earth sciences 2024-08, Vol.272, p.106245, Article 106245
• Main Authors: Saif, Bilal, Tahir, Mohammad, Ali Shah, Muhammad, Naveed Mushtaq, Muhammad, Yousaf Khan, Muhammad, Azad, Azmat, Iqbal, Talat
• Format: Article
• Language: English
• Subjects: Chaman fault; Hazard maps; Peak ground acceleration; Seismic Hazard Assessment; Seismicity; Seismo tectonic modeling; Uniform Hazard Spectra
• ISSN: 1367-9120
• DOI: 10.1016/j.jseaes.2024.106245

The PSHA results and hazard maps can be used for effective disaster reduction in Quetta region. [Display omitted] •PSHA of Quetta city and surrounding areas have been carried out at a 0.1° × 0.1° grid.•New global homogenized earthquake catalogue was compiled for a period of 1250 BCE to 2020.•Two area source models has been used based upon tectonics and seismicity distribution.•The fault sources from GEM database model has been used with the area source model.•Logic tree approach was used in this study to incorporate different uncertainties.•The PGA values for Quetta city are 0.12, 0.30, 0.37, and 0.48 g for 50, 475, 1000, and 2475 return periods. Quetta lies in a seismically active zone of Pakistan with several shallow depth earthquakes occurring frequently. Probabilistic seismic hazard assessment of Quetta city and surrounding regions have been carried out spatially at a grid spacing of 0.1° × 0.1° using the classical Cornell–McGuire approach. Existing earthquake catalogs of Pakistan were recompiled into a new global homogenized earthquake catalog using several international and national databases. It comprises 22,655 earthquake records for a period of 1250 BCE to 2020. Two area source models were considered, both of them include broad tectonic zones and equal weights have been assigned to them. Seismicity distribution within the area source zone was modeled using Kijko and Sellevoll approach. The fault source model has been used with the area source model in one branch that consists of 18 crustal faults with their geological slip rates taken from the Global Earthquake Model (GEM) database. Next Generation Attenuation (NGA) relations were used and a weightage study was carried out to give different weights to GMPEs based on local strong motion data fitting. A rigorous logic tree approach was employed in this study to incorporate different epistemic uncertainties associated with the source models seismicity distribution and the GMPEs. The final outputs of this assessment consist of seismic hazard maps for Peak Ground Acceleration (PGA) and Spectral Acceleration (SA) at the natural periods of 0.2, 1, and 2 s for 63 %, 10 %, 5 %, and 2 % probabilities of exceedance in 50 years respectively. The estimated PGA values for Quetta city are 0.12, 0.30, 0.37, and 0.48 g at the return periods of 50, 475, 1000, and 2475 years respectively. The hazard curves and Uniform Hazard Spectra (UHS) for Quetta city were also developed. These developed hazard maps, curves, and