Seismogenic strength and anatomy of mahendragarh-dehradun fault: implication to seismic risk

We examined stress transfer associated with four moderate earthquakes (M_L ≥ 4.0) along the Mahendragarh-Dehradun Fault (MDF) to assess its seismogenic strength and potential for triggering future events in the Delhi-NCR region. The selected earthquakes occurred on 2006-05-07 (M_L 4.2), 2012-03-05 (M_L 5.1), 2017-06-01 (M_L 4.6), and 2020-05-29 (M_L 4.2). Coulomb Failure Stress (CFS) analysis revealed notable stress redistribution and fault interactions near the MDF and adjacent structures such as the Delhi-Haridwar Ridge (DHR). The 2017 earthquake showed significant stress transfer perpendicular to the MDF, with stress release along the fault itself and enhanced stress in surrounding areas likely influenced by prior events. The faulting mechanisms found normal (2006, 2020), reverse (2012), and strike-slip with reverse (2017) aligned with distinct stress zones, indicating varied rupture dynamics. While the 2006, 2012, and 2020 events occurred in stress concentration zones, the 2017 event was located in a stress reduction zone, highlighting complex fault interactions and stress evolution, suggesting the varying structural heterogeneities associated with MDF at varying depths. These findings emphasize the role of fault geometry, cumulative stress transfer, and rupture style in regional hazard potential. Based on these insights, a seismotectonic model for the MDF is proposed that supports its intricate anatomy, which found very much useful for seismic hazard assessment and earthquake preparedness in the Delhi-NCR.