DEHRADUN: A critical 250-kilometre swathe of land in Uttarakhand, stretching from Tanakpur in Kumaon to Dehradun, is under significant tectonic stress, facing the risk of a major earthquake with a magnitude potentially ranging between 7.0 and 8.0, warn leading geoscientists.
This alert highlights a growing concern over the progressive build-up of seismic energy in one of the most active segments of the Himalayan collision zone.
Dr. Sushil Kumar, a former Senior Scientist specialising in Geophysics at the Wadia Institute of Himalayan Geology, underscored the escalating seismic risk in the region.
He pointed out that Uttarakhand is largely situated across Seismic Zones IV and V, classified by the Bureau of Indian Standards (BIS) as areas of high to very high seismic hazard, with Uttarkashi specifically falling into the highly vulnerable Zone V.
"The absence of a major earthquake in this area over several decades has resulted in growing concern over the progressive build-up of underground energy," Dr. Kumar told TNIE.
"This significantly increases the probability of a large seismic rupture in the near future." Geophysical studies attribute this heightened seismicity to the relentless convergence of the Indian Plate towards the Eurasian Plate, moving at approximately 50 to 52 millimetres per year.
This continuous collision leads to substantial crustal deformation, the accumulation of compressional stress, and frictional locking along major thrust fault systems like the Main Central Thrust (MCT) and the Main Boundary Thrust (MBT).
Dr. Kumar explained that the accumulated tectonic stress, if exceeds the frictional resistance along fault planes, can trigger a sudden and powerful rupture event, culminating in a major earthquake.
The region's history includes significant seismic events, such as the Chamoli earthquake (1999, Mw 6.6) and the Uttarkashi earthquake (1991, Mw 6.8), serving as stark reminders of its seismic potential.
Further, detailed geophysical surveys and seismic monitoring have revealed pronounced thrust fault activity in areas such as Mohand in Dehradun and area near Shanshahi Ashram.
These locations exhibit repeated microseismicity, localised ground deformation, and crustal uplift, meticulously observed through GPS and InSAR (Interferometric Synthetic Aperture Radar) measurements.
These findings strongly indicate persistent tectonic loading and active crustal shortening across this segment of the Himalayas.
Given the complex geological structure, high rate of plate convergence, and a history of significant seismic events, geoscientists are strongly advocating for intensified seismic monitoring, precise fault mapping, probabilistic seismic hazard assessment, and the urgent implementation of robust early warning systems.
These measures are deemed crucial for enhancing earthquake preparedness and developing effective mitigation strategies to safeguard the vulnerable population residing in this high-risk zone.