Unveiling the Evolution Journey from Pangea to Present Himalayan Orogeny with Relation to Seismic Hazard Assessment

Abstract

The objective is to understand incessant seismic activities in Northwest and Central Himalayan regions. GPS data acquired (2017–2020, Nepal; 2015–2019, Uttarakhand) from 65 GNSS stations are used to generate velocity solutions with respect to International Terrestrial Reference Frame 2014 & Indian fixed reference frame to determine the site’s precise position. These velocities are further used to calculate the strain rate and prevailing convergence rate by the respective Triangulation method and Okada’s formulation. The estimated mean maximum and minimum principal strain rate are 12.19 nano strain/yr. and − 102.94 nano strain/yr. respectively. And the respective mean shear strain and dilatation are 115.13 nano strain/yr. −90.75 nano strain, which implies that Higher Himalaya observes high compression rate compared to Outer and Lesser Himalayan region. Estimations have also elucidated presence of extensional deformation in the Northwestern part of the Himalayan arc. Accordingly, in Central Himalaya, paleoliquefaction investigations have deciphered turbidites, confirming that the seismic ruptures did not reach the surface during the 2015 Gorkha earthquake. The best-fit locking depth of 14 km and convergence rate of 21 mm/yr. (Nepal) & 18 mm/yr. (Uttarakhand) are obtained. The strain budget analysis indicates that Northwest and Central Himalaya can beckon a megathrust earthquake in the future.