Is Uttarakhand awaiting Nepal-like quake?

The geologists who warned about "a great earthquake" that devastated Nepal on April 25 have indicated that Uttarakhand has the capability of hosting one.

"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, and his colleagues.

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.

"This prolonged seismic quiescence has led to the proposition that this region, with a population of more than 10 million, is overdue for a great earthquake," the scientists warned.

A little more than a month later on April 25, the area experienced a magnitude 7.9 earthquake centered in Nepal.

The toll in the massive earthquake has crossed 7,000. The temblor has left thousands injured and millions displaced.

The researchers used a series of complementary geomorphic and erosion rate data to define the ramp-flat geometry of the active detachment fault that is likely to host a large earthquake within the hinterland of the northwest Himalayas.

Their analysis indicates that this detachment is sufficiently large to host another great earthquake in the western half of the central Himalayan seismic gap.

Specifically, the data sets point to a distinctive physiographic transition at the base of the high Himalaya 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.