Liquefaction hazard mapping of the south-central coastal areas of Bangladesh

Abstract

Liquefaction can cause significant damage to the built environment; therefore, assessing the liquefaction hazard in a seismically active region is essential to minimize the risk. This study attempted to evaluate the liquefaction potential of the south-central coastal areas of Bangladesh by calculating the liquefaction potential index (LPI) considering a scenario earthquake of Mw = 7.5 having a peak ground acceleration of 0.15g. For calculating LPI, both standard penetration test blow count (SPT-N) and shear wave velocity (Vs) data have been used in this study. The results show that the study area's LPI values vary from 0 to 37. A liquefaction hazard map is prepared for the area using the calculated LPI values from Vs data shows about 8% of the study area is very highly susceptible to liquefaction hazard, whereas 62% of the area falls under high hazard-prone area while about 28% and 2% area of the study have respectively low (0<LPI ≤5) and very low (LPI = 0) liquefaction potentiality. In addition, after analyzing the study area's fluctuating groundwater level (GWL) during the last 20 years, it has been observed that the GWL is likely to rise, thereby intensifying the potentiality of liquefaction hazards in the future. The outcome of this study will help engineers, urban planners, and policymakers to prepare a risk-sensitive land use plan and to develop a robust earthquake emergency response plan to reduce seismic risk.