An analysis of the AD1762 earthquake and tsunami in SE Bangladesh

Abstract

In AD1762, a large earthquake originating within the Arakan Subduction Zone occurred. However, conflicting opinions exist as to whether this earthquake triggered a major regional tsunami in the northern Bay of Bengal (BoB) that struck southeast Bangladesh. This research aims to review and assess the effects of the AD1762 earthquake in Bangladesh and reviews what effects associated tsunamis had along the coast of southeast Bangladesh. Through field visits and investigations, this research confirms the locations of liquefaction, compaction, landslides, co-seismic subsidence, deaths and injuries using the descriptions of historical documents as a guide. The earthquake triggered land-level changes where the soil is young and soft, and these areas are located adjacent to the coast of the BoB and along the banks of the Karnafuli, Halda and Meghna rivers. The earthquake probably generated several submarine sediment slides that triggered local tsunamis that struck different locations (Bansbaria, Bharchhara and Burumchhara) along the Chittagong coast. Following an analysis of the earthquake effects, we consider that a repeat of the AD1762 earthquake would result in significant damage to fragile infrastructure and to vulnerable communities in Bangladesh. Further, we recommend (1) conducting geological and geomorphological studies at key sites to assess the nature and extent of land-level changes; (2) undertaking socially oriented community vulnerability assessments to earthquakes and tsunamis; and (3) implementing a variety of risk-reduction strategies to reduce vulnerability and enhance resilience to future events.