A GIS Based Mapping of Seismic Parameters in Tectonically Active Mikir Massif Region of Assam, India

Abstract

The Mikir massif area of Assam is considered one of the deformed zones of the north-eastern region (NER) as demonstrated by its seismicity. The present study aims to study the active tectonics in the Mikir massif region with the help of hypocentral parameters, frequency–magnitude relation, and ‘b’ and ‘a’ values of earthquake events. The major structures and existing lineaments of the area are correlated with the seismicity pattern and areas having low seismicity and less heterogeneity has been demarcated based on seismic parameters. The seismicity in the area shows a higher concentration of earthquake events towards NW compared to other parts. The depth section of earthquake events along and across the regional faults shows that all the major structures and lineaments with distinct topographic expressions can be identified from the seismic profile. The activeness of those faults and lineaments can be accessed by the cluster of seismic events that occurred spatially and also at depth. Classification of the area into 4 different seismogenic zones shows higher values of seismic parameters (Mc, a, and b) for Zone A, followed by Zone C, Zone B, and Zone D. The higher seismicity associated with these zones is also confirmed by high lineament density in those areas. The lower b and a- value associated with Zone D implies that the area is seismotectonically stable with fewer numbers of seismic events and hence suitable for any civil engineering construction.