Geodetic and Seismic Investigation of Crustal Deformation in Northwest Himalaya

Abstract:

Underthrusting of Indian plate beneath the Eurasian plate results into a persistent compression and strain accumulation along a north-dipping detachment zone in the Himalayan orogen, producing a number of moderate and great interplate earthquakes. In this study, we present the ongoing crustal deformation from our GPS network comprising eight continuously operating permanent stations and three profiles of campaign stations which are lined up perpendicular to the Himalayan mega thrust faults. The campaign stations clearly reveal the ongoing deformation near the Himalayan Frontal Thrust (HFT) and the Main Boundary Thrust (MBT) zones. We further combine our geodetic results with the probalistic earthquake hazards of the northwestern Himalaya (28⁰–32⁰N, 74⁰–80⁰E) to provide a comprehensive report on the seismic hazard scenario of the thickly populated Himalayan cities. For this, the earthquake interevent times and conditional probabilities for events exceeding magnitude 6.0 are estimated from thirteen different probability models, namely exponential, gamma, lognormal, Weibull, Levy, Maxwell, Pareto, Rayleigh, inverse Gaussian (Brownian passage time), inverse Weibull (Frechet), exponentiated exponential, exponentiated Rayleigh (Burr type X), and exponentiated Weibull distributions.