On February 17, 2025, a magnitude 4.0 earthquake occurred near Jheel Park in South Delhi, approximately 6 km from the epicenter of the November 25, 2007, M4.6 event, one of the most significant regional earthquakes in recent decades. The tremor was widely felt across Delhi and adjoining regions, accompanied by a distinct rumbling sound. For the first time, a comprehensive seismo-geodetic investigation was conducted to characterize the causative source mechanism and fault geometry of this event. Data from the dense network of the National Seismological Network (NSN) enabled precise focal mechanism determination, indicating predominantly strike-slip faulting at a centroid depth of 41 km. Fault-plane solutions and strong-motion recordings suggest rupture along a NW-SE-oriented fault system, associated with the pre-existing Sohna and Mathura Faults. The maximum peak ground acceleration (PGA) recorded at the nearest station (~ 25 km) was 0.0026 g. No aftershocks were observed in the six months following the mainshock, suggesting a stable post-seismic regime. Stress field inversion aligns with the regional strike-slip stress environment, consistent with the seismicity pattern since 1960. Local subsurface heterogeneities including weak rock zones, fluid-saturated sediments, and relict riverine deposits likely influenced the rupture initiation. The earthquake is interpreted as a strike-slip event triggered by fluid-assisted weakening (hydrofracturing) of fault zones. These findings underline the role of crustal fluids in Delhi's intraplate seismicity and provide valuable constraints on fault behaviour and earthquake hazard in the region.
Prajapati et al. (2026) studied this question.