Seismicity and seismotectonics of Indo Burma orogenic belt and earthquake hazard implications in northeast India

Abstract

The Indo-Burma Orogenic Belt is an important geotectonic element of southeast Asia and seismically active region of the world it falls under the Alpine-Himalayan Earthquake Belt. The evolution of the belt can be considered as the result of continent-continent or continent-island arc collisions that continued convergence with Eurasia. The area as a whole exhibits a well-defined arcuate belt analogous to the present day island arc it represents the outer Arc Ridge in an arc-trench setup comprising of Eocene-Oligocene flysh and sub-flysh scraped off form the leading edge of the indian plate along with narrow strips of older Paleozoic-Mesozoic sediments, patches of metamorphic and dismembered ophiolites. The significant characteristic of this belt is the occurences of shallow to intermediate focus earthquakes found within a continental environment. Because of its complex geotectonic setting due to the interaction between the active north-south convergence along the Himalayas and the east-west convergence and folding within the Indo-Burman ranges with very high seismicity, the region tends to be considered as one of the critical segments of the world for the study of earthquake generation. The present study with imputes from geological and seismological database would provide further insight into the present scenario of the seismic activity that apparently evolves from subduction. Several workers attempted to study the seismicity and seismotectonics of the region: however, most of these studies are mainly based on seismicity recorded at teleseismic distances. With the establishment of local seismic networks in the region during the last few decades, volume of good quality data has increased significantly enabling to add significant details and refinements into the study of the seismicity of the region in that context, the main objectives of the present study are related particularly to the active tectonics and seismicity of the indo-Burma orogenic belt within latitude 200N-280N and longitude 930E-980E and probable...