RAS question
The September 2025 Assam earthquake was located near which geological fault?
Correct answer: (B) Kopili Fault.
The September 2025 Udalguri, Assam earthquake was located near the Kopili Fault.
Explanation
The September 14, 2025 earthquake in Udalguri, Assam, recorded by the National Centre for Seismology, had a magnitude of 5.8 and was located near the Kopili Fault. That placement matters because the same preliminary report notes that it lay close to the April 28, 2021 M 6.4 Sonitpur earthquake area, showing why this fault zone is a recurring reference point in Assam seismicity. The explanation is also consistent with the hazard setting: the Assam region is placed in the highest seismic hazard Zone V on the Bureau of Indian Standards seismic zoning map. So, among the listed faults and thrusts, Kopili Fault is the fault specifically tied to this event.
Why the other options are wrong
- (A) Dauki Fault is not the fault identified in the cited preliminary report for the September 2025 Udalguri earthquake.
- (C) Naga Thrust is not named as the nearby fault for this event; the report specifically links the earthquake to the Kopili Fault.
- (D) Main Boundary Thrust is one of the Himalayan tectonic sources mentioned for the wider region, but it is not the fault near which this earthquake was located.
Concept
This tests the RAS syllabus link between earthquakes, active faults and seismic hazard zonation in north-eastern India. Such questions recur because Assam combines current seismic events with map-based fault and hazard-zone facts.