Researchers combined GNSS and satellite radar data to examine the locked Uttarakhand Himalayan fault. Their findings sharpen concerns about long-term seismic hazards across the densely populated region.A beautiful view of snow capped Himalaya range and Joshimath from Cable car which connects Joshimath and Auli.
The fault beneath the Uttarakhand Himalayas is strongly locked and accumulating tectonic strain, with the stored energy equivalent to that released by a magnitude 8.1 earthquake approximately every 100 years, a new study has found.The research raises concerns about the long-term seismic potential of the central Himalayas, a region that scientists consider part of a major seismic gap. The findings are particularly significant for the adjoining Indo-Gangetic plains, one of the world's most densely populated regions.Titled Evidence of strong plate coupling in the Uttarakhand Himalayas: Constraints from GNSS and ALOS-2 InSAR observations, the study was conducted by Dibyashakti Panda, Mridul Yadav, Eric O.
Lindsey and G Srinivasa Rao from the Central University of Tamil Nadu.The researchers combined measurements from Global Navigation Satellite System (GNSS) stations with satellite radar observations from Japan's ALOS-2 mission to investigate how the Main Himalayan Thrust (MHT), the major fault associated with the collision of the Indian and Eurasian plates, is behaving. The study identified vertical ground deformation.
Their analysis found a slip deficit of approximately 18 millimetres per year, suggesting that a substantial portion of the ongoing plate movement is not being accommodated through steady sliding along the fault.The researchers estimate that the MHT remains locked across a width of around 115 kilometres. Such locking allows the surrounding rocks to deform as the Indian plate continues moving towards the Eurasian plate, accumulating elastic strain that can potentially be released during an earthquake.SATELLITE OBSERVATIONS REVEAL GROUND UPLIFT The study also identified vertical ground deformation, with ALOS-2 Interferometric Synthetic Aperture Radar (InSAR) observations indicating peak uplift of 4-6 millimetres per year.The researchers used an Elastic Subducting Plate Model (ESPM) to explain both horizontal and vertical ground movements.
According to the study, the model reproduced the observed deformation patterns without introducing artefacts.Together, the GNSS and satellite radar observations support the conclusion that the Himalayan megathrust beneath Uttarakhand is highly coupled, reinforcing concerns about the region's accumulated tectonic strain. The findings provide new constraints on the behaviour of the Himalayan fault system.
A SEISMIC GAP UNDER SCRUTINYUttarakhand forms part of the central Himalayan seismic gap, where significant portions of the megathrust have not ruptured in major earthquakes for more than 200 years.Scientists have differed over the extent of plate locking in this region, leading to varying assessments of its seismic hazard.The researchers estimate that the accumulated strain energy is equivalent to that released by a magnitude 8.1 megathrust earthquake approximately every century.However, this is an estimate of strain accumulation, not a prediction that an earthquake of that magnitude will occur on a fixed schedule. The study does not establish when the next major earthquake will strike.The findings provide new constraints on the behaviour of the Himalayan fault system and underline the importance of understanding long-term earthquake hazards in a densely populated region.- Ends