LAUSR

The NE–SW trending Mahendragarh–Dehradun Fault (MDF) is a basement fault in the western Ganga plain. The earthquake (4.7 m b ) epicentered on this fault on 2nd June 2017 was focused around 10 km depth and does not show any surface rupture. Ground Penetrating Radar (GPR) survey around the epicenter detects few shallow-depth subsurface normal faults parallel to the MDF. However, it is unclear whether these normal faults are linked with the 2017 earthquake or other previous earthquakes. Seismic record (USGS) since 1975 to 2017 suggests occurrence of 22 earthquakes (~ 5  m b ) around the MDF and majority (~ 63%) of these are clustered around Delhi and Rohtak. Following the 2017 earthquake, frequency of earthquakes occurence sharply increased than previously recorded instrumentation period from 1975 to 1995. Majority of the seismicity is focused around 10 km depths, shallowing to depths of 25–207 km recorded from 1975 to 2004. Earthquakes clustered along the Main Himalayan Thrust (MHT) shows similar temporal trend as near the MDF. Southward thrust movement of the Himalaya orogenic wedge predicts to impose strike-slip motion on the orthogonal-oriented steep basement faults, which is consistent with geologic and geomorphic field relations, and seismicity focal mechanisms along the MDF. The observed upper crustal deformation associated with such fault deformation pattern may be partly influenced by the MDF and partly by the foreland bulge seismicity. Potential tectono-geomorphic parameters and soil-chronosequence may suggest the surface deformation is active through the Holocene.