Himalayan Geology, Vol. 43 (1A), 2022, pp. 1-11, Printed in India

Seismic imaging of intra-crustal low velocity layer beneath the Kishtwar region, North-West Himalaya, India using receiver function technique

CHINMAY HALDAR, KALACHAND SAIN*, SUSHIL KUMAR

Wadia Institute of Himalayan Geology, 33 GMS Road, Dehradun-248001, India

*Email (Corresponding author): kalachandsain7@gmail.com

Abstract: The converted wave seismological data across the Doda-Kishtwar region in the Kashmir seismic gap of North-West Himalaya has been used in this study. The results based on inversion of receiver functions (RFs) reveals, for the first time, the crustal velocity-structure with a Low-Velocity Layer (LVL). The crustal thickness varies from 47 km to 58 km from south to north, and the Main Himalayan Thrust exists at depth between 21 to 26 km. The LVL with its top lying at 11 to 13 km extends downward up to a depth of 29 km, and shows Vp/Vs of 1.9. This high value of Vp/Vs may be explained by the presence of fluid/fractional melt in the depth range between 10 to 15 km. We suggest that the LVL and hence the fluids/melts could be one of the possible reasons for the generation of upper-to-mid-crustal earthquakes. Interestingly, the LVL coincides with the focal depths of most of the earthquakes, observed in this region.

Keywords: Crust, Moho, Kishtwar, Receiver Functions, Low-Velocity Layer, NW Himalaya