An Appraisal of Recent Earthquake Activity in Palghar Region, Maharashtra, India
D. Srinagesh, Dhiraj Kumar Singh, G. Vikas, B. Naresh, Sunil K. Roy, Y. V. V. B. S. N. Murthy, P. Solomon Raju, G. Suresh, Prantik Mandal, Aryan Sharma, M. Shekar, V. M. Tiwari
Abstract
The present study focuses on the recent earthquake activity in Palghar region, Maharashtra, India. Until 31 August 2019, a total of 4854 earthquakes have been located here, whose local magnitude (M L ) varied from 0.1 to 4.1. Majority of the earthquakes (~94%) were located in the depth range 4-16 km. The precise earthquake relocations reveal two clusters. The N-S trending cluster north of 20.04N extends to a depth of 10 km, whereas the NE-SW trending cluster to the south of 20.04N extends to 16 km depth. The shallow northern cluster is noticed to be sandwiched between two mapped mafic intrusions, whereas the deeper southern segment shows earthquakes clustering around the mafic intrusion. The modelled composite focal mechanism solutions for both the north and south clusters suggest normal faulting with a minor strike-slip component as the dominant deformation mode for the Palghar region. From relocated seismicity, we have detected a deeper seismically active zone (with M > 3) at 4-16 km depth, occupying a crustal volume of 1440 km 3 (i.e. 20 km (in N-S) 6 km (in E-W) and 12 km (in depth)) that dips toward 20S and 70W. This could be attributed to the large crustal stresses induced by the mafic intrusive body below the region.