A moderate earthquake measuring 5.1 on the Richter scale struck central Assam on January 5, 2026, with the epicenter precisely located near Morigaon district at coordinates 26.37°N latitude and 92.29°E longitude. The National Center for Seismology (NCS), the primary government agency responsible for monitoring seismic activity across India, confirmed the event occurred at exactly 4:17 am IST, originating from a depth of 50 kilometers, which contributed to widespread but moderated surface shaking.

This seismic activity traced its origins to the active Kopili fault line, a prominent northeast-southwest trending transpressional fracture zone known for generating strike-slip earthquakes in the region. The fault, extending approximately 300-400 kilometers across Assam and neighboring areas, has a documented history of producing significant events, including major earthquakes in 1869 and 1943. The deeper focal depth of this quake likely attenuated intense surface vibrations, yet it still triggered considerable alarm as buildings swayed and household items rattled in the pre-dawn darkness amid persistent winter fog and cold temperatures.

Tremors propagated extensively beyond Assam's borders, affecting central and western parts of Arunachal Pradesh, the entirety of Meghalaya including Shillong, and multiple districts in Nagaland, Manipur, Mizoram, and Tripura. Reports also indicated mild shaking reaching certain areas of northern West Bengal. Startled residents across these states, many still asleep at the early hour, fled their homes in panic, gathering in open spaces for safety, though the event's moderate intensity and depth prevented widespread disruption.

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Initial assessments from local authorities and emergency services across the affected regions confirmed no reports of casualties, injuries, or significant structural damage to buildings, infrastructure, or property. Ongoing monitoring for potential aftershocks continues, with officials advising residents to remain cautious and adhere to standard earthquake safety protocols, such as securing heavy objects and identifying safe evacuation points.

The Northeast Indian region, encompassing Assam and its neighboring states, is designated as Seismic Zone V—the highest vulnerability category in India's zoning map—due to its position at the convergence of the Indian and Eurasian tectonic plates, compounded by active faults like the Kopili lineament. This inherent geological instability necessitates rigorous enforcement of earthquake-resistant construction norms, community awareness programs, and advanced early warning systems to mitigate risks from frequent seismic occurrences in the area.

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