Rangamati Earthquake

Keynote Speech: Workshop on Earthquake Disaster Preparedness and Mitigation Organised by Identification Mission Consultants to the EU Delegation-Bangladesh February 18, 2004, Dhaka, Bangladesh

ABSTRACT
Seismic hazard assessment of an earthquake prone region involves a wide range analysis of seismological and geological data and engineering characterization of geological materials. The earthquake history of Bangladesh and surrounding region indicates that the country is seismically active. The regional geological setup of the landmass is complex due to the juncture of Himalayan Arc of northeast India and the India-Myanmar plate subduction to the east. The plain-land topography of Bangladesh musk the subsurface depositional variations and all geological structures except in the hilly region. Seismic hazard assessment is not simple for such covered complex geological environment.
This paper present the basic factors related to geology, tectonic environment and geotechnical conditions for rationale seismic hazard assessments. An attempt is made to understand the relationships among tectonic setting, structural and crustal configuration of Bengal basin to classify the earthquake source areas. Three types of earthquake sources areas are identified: a. Intra-plate source areas, b. Transitional source area and c. Inter-plate source area. The seismic behaviour of these source areas is deeply related with the tectonic structure and basement or crustal configuration of Bengal basin.
Epicenter locations of recent earthquakes in Bangladesh indicate that there are number of active faults in these source areas. The physical attributes and exact locations are not known. A detailed investigation on the geometry and mechanics of these active faults is essential to determine the relationship among geo-technical behaviour of materials, local geological constraints and ground response. An account on these relationships are presented in this paper.