3D crustal structure, earthquakes and ground motion simulation in the Jammu and Kashmir Himalaya

Starts:  22 January 2026  16: 00

Ends:   22 January 2026   17:00

Central Africa Time (CAT)

Speaker:

Prof. Supriyo Mitra

Department of Earth Sciences & Center for Climate and Environmental Studies

Indian Institute of Science Education and Research Kolkata (IISER-K)

Abstract:

The NW Himalayan “seismic gap” lies between the rupture zones of the 1905 Kangra and 2005 Kashmir earthquakes, and straddles the meisoseismal zone of the 1555 earthquake. This region is marked by hinterland-to-foreland reduction in GPS-geodetic arc-normal convergence-velocity and increase in horizontal strain-rate, associated with occurrence of moderate-to-small earthquakes. These point to sufficient elastic strain accumulation to drive a megathrust earthquake. We model the crustal structure and geometry of the Main Himalayan Thrust (MHT) and locate moderate-to-micro seismicity using the Jammu and Kashmir Seismological NETwork (JAKSNET) data. Body-wave common-conversion-point (CCP) stacks, and joint inversion with surface-waves are used to construct a 3D Vs model. This reveals increasing crustal thickness from foreland-to-hinterland, and an under-thrust Indian crust beneath NW Himalaya. The Moho deepens from the Sub-Himalaya to Higher/Tethyan Himalaya with a gentle NE dip. The MHT forms a low-velocity layer and has a flat-ramp geometry. 610 local earthquakes, located using the 3D Vs model, are shallower than 20 km, and lie on or above the Main Himalayan Thrust (MHT), clustered beneath the Jammu-Kishtwar Higher Himalaya. These have been used to show the presence of a Lesser Himalayan duplex (LHD) beneath the Kishtwar Window and MHT lateral-ramp and transverse structures within the Himalayan wedge. Finally, the knowledge of field geological observations, earthquake fault geometry and attenuation characteristics are used to simulate peak ground motions for different scenario earthquakes.

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