The fear psychology knows no bounds and now some geologists who had warned about “a great earthquake” that devastated Nepal on April 25 have turned their attention to Uttarakhand saying it has all the potential to experience similar earthquake.
“The landscape and erosion rate patterns suggest that the decollement beneath Uttarakhand provides a sufficiently large and coherent fault segment capable of hosting a great earthquake,” said study authors C.P. Rajendran from the Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore.
In their study reported in March, the scientists wrote: “The (approximately) 700-km-long ‘central seismic gap’ is the most prominent segment of the Himalayan front not to have ruptured in a major earthquake during the last 200-500 years.
Attributing their base to prolonged seismic quiescence, they say the region of Uttarakhand, with 10 million population, could be the next as it is long overdue in this reagion, they said.
The 700-km-long Uttarakhand comes under the “central seismic gap”, a prominent segment of the Himalayan front that has not experienced any major earthquake for over 500 years called prolonged seismic quiescence has led to the proposition that this region, with a population of about 10 million, is overdue for a great earthquake.
“Despite the region’s recognized seismic risk, the geometry of faults likely to host large earthquakes remains poorly understood. Here, we place new constraints on the spatial distribution of rock uplift within the western ∼400 km of the central seismic gap using topographic and river profile analyses together with basin-wide erosion rate estimates from cosmogenic 10Be,” said researchers.
Kristin D. Morell, Mike Sandiford, C.P. Rajendran, Kusala Rajendran, Abaz Alimanovic, David Fink and Jaishri Sanwal, who wrote the paper titled, “Geomorphology reveals active décollement geometry in the central Himalayan seismic gap.”
With a distinctive physiographic transition at the base of the high Himalaya, Uttarakhand is characterized by abrupt strike-normal increases in channel steepness and a tenfold increase in erosion rates.
“When combined with previously published geophysical imaging and seismicity data sets, we interpret the observed spatial distribution of erosion rates and channel steepness to reflect the landscape response to spatially variable rock uplift due to a structurally coherent ramp-flat system of the Main Himalayan Thrust,” wrote the researchers.
Geomorphology reveals active décollement geometry in the central Himalayan seismic gap
Although it remains unresolved whether the kinematics of the Main Himalayan Thrust ramp involve an emergent fault or duplex, the landscape and erosion rate patterns suggest that the décollement beneath the state of Uttarakhand provides a sufficiently large and coherent fault segment capable of hosting a great earthquake, said researchers.
Since the region’s detachment to Nepal earthquake is is sufficiently large enough, it may host another great earthquake in the western half of the central Himalayan seismic gap.
They point out a distinctive physiographic transition at the base of the Himalayas in Uttarakhand, characterised by abrupt strike-normal increases in channel steepness and a 10-fold increase in erosion rates.
“While this hypothesis remains speculative, it is supported by independent records of historical seismicity,” they noted.
The study appeared in the journal Lithosphere.