Liquefaction Hazard Scenario of Imphal City for 1869 Cachar and a Hypothetical Earthquake

Abstract

In the present article liquefaction potential of Imphal city is reported in the form of two indices, i.e., LPI (Liquefaction Potential Index) and LSI (Liquefaction Severity Index), for 1869 Cachar earthquake (Mw 7.5) along the Kopili fault and probable future great earthquake (Mw 8.1) in the Indo-Burma subduction zone. The Factor of Safety (FS) against liquefaction has been computed by using modified procedure given by Idriss and Boulanger (2006) for all depths of 122 boreholes. The computed FS have been used as input parameters for evaluating LPI and LSI indices for Imphal City. Based on these LPI and LSI indices, liquefaction potential hazard contour maps of Imphal city is prepared. It is observed that over a large area of Imphal city is highly vulnerable to liquefaction failure in the events of the selected earthquake. The liquefaction hazard obtained at each site exhibits a good agreement with the damages documented for 1869 Cachar earthquake. This contour map can be served as a guideline for engineer and planner in site selection for upcoming projects and helps city administration in mitigating the city from future hazards.

Site-characterization using 1D/2D/3D Site Response Modelling vis-à-vis Surface-consistent Probabilistic Seismic Hazard, Microzonation and Damage Potential Studies in the Six-Tectonic Ensemble consisting of Kashmir Himalaya to Northeast India

“…The seismic loading causes a sudden increase in pore water pressure and the gaps between soil grains, leading the soil to loosen its cohesive strength and behave like a liquid. The Brahmaputra Valley of Northeast India, Indo-Gangetic Foredeep, Bengal Basin and Northwest India are particularly susceptible to liquefaction, as documented in the regions such as Jammu (Ansari et al 2022), Kashmir Valley (Sana and Nath 2016), Lucknow (Kumar et al 2013), Delhi (Rao and Satyam 2007), Kathmandu (Subedi and Acharya 2022;Pokhrel et al 2022), Bengal Basin including Bangladesh (Nath et al 2022), Guwahati (Raghukanth and Das 2010), Agartala (Das et al 2019) and Imphal (Pallav et al 2012). A comprehensive analysis of soil liquefaction has been conducted for the present Tectonic Ensemble, utilizing geotechnical data to simulate liquefaction susceptibility due to historical earthquakes and predict probabilistic scenarios for the Basin.…”

Soil Liquefaction and Its Evaluation Based on SPT by Soft-Computing Techniques

“…The average standard penetration resistance ( ̅ ) at any boreholes is computed by the following expression (Pallav et al, 2012).…”