Abstract:
The continent-continent collision between India and Asia has resulted
in the spectacular Himalayan mountain range, development of large fold and
thrust sequences and greater than 1500 km shortening of the crust (Molnar &
Tapponnier, 1975; Yin, 2006). The Indian plate is being underthrusted beneath
the Eurasian plate along a north-dipping detachment surface named as Main
Himalayan Thrust (MHT), separating down-going Indian plate from
overriding Himalayan wedge (Seeber et al., 1981). The over-thrusted wedge
was formed due to uplift along south-verging thrust planes located from north
to south. The Himalayan wedge adjoins with the lithotectonic units: Tethyan
Himalaya, Higher Himalaya, Lesser Himalaya and Sub-Himalaya. These lithotectonic
units are separated by faults viz. South Tibetan Detachment System
(STDS), Main Central Thrust (MCT) and Main Boundary Thrust (MBT),
respectively. The Himalayan wedge is confined between the Himalayan
Frontal Thrust (HFT) at the south separating the Sub-Himalaya from the Indo-
Gangetic Plain (IGP) and Indus-Tsangpo Suture zone (ITSZ) towards the
north, which is considered as the surface collision boundary of India-Asia
collision. The major thrust faults are assumed to sole into the detachment-
MHT (Seeber & Armbruster, 1981; Ni & Barazangi, 1984; Zhao et al., 1993;
Yin, 2006; Avouac, 2007). The MHT accumulates the strain energy originated
due to collision and releases accumulated energy in the form of large/great
earthquakes e.g. the 1905 Kangra earthquake of magnitude Mw 8.0 and the
1934 Bihar-Nepal earthquake of magnitude Mw 8.0 (Middlemiss, 1910; Ni &
Barazangi, 1984; Kayal et al., 2001). Seismological studies reported a ramp
structure on the MHT that causes earthquakes (Pandey et al., 1995; Caldwell
et al., 2013; Duputel et al., 2016). Significant variation of seismicity along the
strike of the northwest (NW) Himalaya has been reported by recent studies
(Gahalaut & Kalpna, 2001; Arora et al., 2012). Seismicity in the NW
Himalaya mostly concentrates in the Himalayan Seismic Belt (HSB), a narrow
belt of 30–50 km width spanning the northern Lesser Himalaya and the
southern Higher Himalaya (Arora et al., 2012).
