Seismic Risk Analysis And Crustal Thickness Identification With Prospective Destruction To Infrastructure In Gilgit City And Surrounding Areas, Pakistan

Abstract

Pakistan is a country that holds a key position in South Asia due to its regional topography. Gilgit experiences frequent earthquakes due to its tectonic position between the Indian and Asian continental plates. Two major seismic zones; Main Karakoram Thrust (MKT) and Main Mantle Thrust (MMT) have been identified to create great seismic activity in the surroundings of Gilgit City. It is important to understand the seismicity patterns of earthquakes in Gilgit city based on their source mechanism. The key objective of the research was to assess the causes of Earthquakes and predict the possibility of forthcoming earthquakes.  The waveform data was utilized and for the first time, deeper crustal structure was determined successfully. Seismological data was used to evaluate the crustal thickness and structure of the S-wave velocity underneath the Gilgit area. Primary wave receiver function (PRF) analysis, H-K stacking and inversion techniques were applied for this purpose. A new crustal model for S-wave velocity with maximum crustal thickness was identified. H-K stacking technique occurred to the receiver functions representing estimating the width of crust (H) and Poison ratio (K). The reasonable stable and high horizontal velocity and phase of a teleseismic P-wave were identified. The GSAC tool and the Computer Programmed in Seismology CPS.330 were used to obtain seismograms of earthquake events in the past two years. Also, the SALENA risk tool was utilized for the estimation of loss and damage considering the worst-case scenario for the Earthquake (Mw 7.0) along the MMT zone of Gilgit City.