Rational Way of Estimating Liquefaction Severity: An Implication for Chattogram, the Port City of Bangladesh

Abstract

Earthquake-induced liquefaction is responsible for the extensive damage to the infrastructures in both developed and developing cities. Chattogram, the second largest city of Bangladesh and one of the vital port city in the south Asian region is situated in the active seismic region, and the frequency of recent small magnitude earthquakes around the city reveals that a significant earthquake of probable magnitude 7.0 or higher is due. Therefore, liquefaction severity at different locations of Chattogram Metropolitan Area is estimated based on the in situ parameters. Two widely used liquefaction assessment procedures has been applied to estimate the liquefaction susceptibility at the selected locations. Later, geospatial techniques are applied to prepare a hazard map based on liquefaction potential of discrete locations. The flat tidal part of the city is identified as extremely liquefy prone areas, while the small hillocks and nearby areas at the central part of city are safe against liquefaction hazard. Geological variation of parameter in all directions are also taken into account to prepare the hazard map. Predicted liquefaction potential is then compared with a second data set and the linear regression between the observed and predicted liquefaction potential portray consistent approximation in all cases. Case studies and practical experience also justify the developed hazard map. Therefore, the developed hazard map can be a useful tool for the disaster mitigation policy of Bangladesh Government.