Earthquake Shocks Around Delhi-NCR and the Adjoining Himalayan Front: A Seismotectonic Perspective

Abstract

An increase in the number of earthquakes and subsequent clustering in northwest India, particularly around the Delhi-National Capital Region (NCR) and adjacent NW Himalayan front, provides a good opportunity to understand the underpinning tectonic controls and the likelihood of any large earthquake in the future. The 2001 Mw 7.7 Bhuj, 2011 Mw 6.9 Sikkim and 2015 Mw 7.8 and 7.3 Nepal earthquakes (and 2004 Mw 9.2 Sumatra event) are important in this context. We analyzed the seismicity around the Delhi-NCR and the adjoining Himalayan front, including event clustering and the spatio-temporal distribution of b-values, in the context of kinematics and the regional geodynamics. The overall moderate-to-low b-values, both in time and space, since 2016, provide information regarding an increase and subsequent stabilization of the stress field in the study area. The analysis led to the identification of (1) a structurally guided stress field in the region between the Kachchh and the NW Himalaya that coincides with the direction of Indian plate convergence and (2) frequent occurrences of earthquakes particularly in the Delhi, Kangra and Uttarkashi areas. We propose that faults in western Peninsular India, which pass through the margins of the Aravalli Range, the Marwar basin, and the isostatically over-compensated Indo-Gangetic Plains beneath the under-plated Indian lithosphere, act as stress guides; concentrating and increasing stress in regions of lithospheric flexure. This enhanced stress may trigger a large earthquake.

Archeoseismic Study of Damage in Medieval Monuments around New Delhi, India: An Approach to Understanding Paleoseismicity in an Intraplate Region

“…New Delhi is one of the largest cities in India, with a population of approximately 20 million and is located about 250 km SW of the seismically active Himalayan Belt, which is well known for generating large-magnitude earthquakes [21,22,80]. Delhi is part of the Delhi-Aravalli Fold Belt (DAFB), bounded by the Indo-Gangetic Plain in the north and the Aravalli Mountains in the south.…”

“…Delhi is part of the Delhi-Aravalli Fold Belt (DAFB), bounded by the Indo-Gangetic Plain in the north and the Aravalli Mountains in the south. The terrain is generally flat except for the low-relief NNE-SSW-trending Delhi-Haridwar Ridge in the southern and central parts of the area [22,80]. New Delhi and its surrounding regions are situated on the Proterozoic folded meta-sedimentary quartzite and metapelite of the Delhi-Aravalli Fold Belt (DAFB) [81][82][83][84][85].…”

“…Significant earthquake events that caused damage around Delhi with local MM intensity[32,34,44,[72][73][74][75][76][77][78][79][80][81][82][83][84][85][86][87].…”

Crustal Configuration and Seismic Stability of the Eastern Indian Shield and Adjoining Regions: Insights for Incidents of Great Earthquakes in the Nepal-Bihar-Sikkim Himalaya

“…The ∼N-S striking aseismic 85 and 90 • E ridges divide the BOB into three main sub-basins (Gopala Rao et al, 1997), apparently guiding the active stress of the lithosphere, linking the Himalayan operative tectonics through the EIS, Singhbhum craton, and the IGB. Several faults and lineaments on both sides of the Munger-Saharsa ridge are intersecting the Foothills of the Himalaya, and these geo-fractures are likely extended all through the Gangetic basin, concentrating and raising the stress in the flexing zone of the subducting Indian crust (Sibson, 1980;Marshak and Paulsen, 1997;Godin and Harris, 2014;Khan et al, 2017a;Khan et al, 2021). The plate obliquity of 0 • to less than 10 • of the Nepal-Bihar-Sikkim area (Khan et al, 2014) further enhances and confines the stress field around the flexing zone through interacting fractures and triggering great earthquakes by the stress build-up processes.…”