Deadly earthquake hits W NepalSeismologists had predicted that a megaquake was long overdue in western Nepal
Himalayan seismologists have been warning that a mega earthquake is long overdue in western Nepal because there has not been a big one to release the tectonic tension there for over 600 years.
The estimated 6 magnitude earthquake just before midnight on Friday with an epicentre in Jajarkot was exactly in this region, but not the 8+ magnitude that had been predicted. The official death toll in the remote villages of Karnali Province is now 125 with hundreds injured, but these figures are expected to rise.
Friday night’s earthquake rattled Kathmandu and New Delhi, both 500km away and shook the densely populated plains of northern India as well as the Tibetan Plateau. There has been an increase in seismic activity in the region: there was a double jolt of 5.3 and 6.3 magnitude epicentred in Bajhang district in far-western Nepal on 3 October that killed one person.
The fact that the Jajarkot quake struck in the seismic gap in western Nepal may mean that some of the tension that has been building up beneath may have been released, but it could also be a precursor quake to a bigger one.
The Indian Plate is converging towards the Eurasian Plate at an average rate of 25mm a year, which is what makes Nepal and the region an active seismic zone. The energy is released in periodic earthquakes, but there is a large seismic gap in western Nepal which has not suffered a mega quake since the 16th century. This means the accumulated tectonic energy needs to be released.
Seismologists say Friday’s earthquake may not have been strong enough to release all that built-up tectonic pressure. There have been predictions that an 8 magnitude earthquake could see horizontal surface displacement of more than 6 metres along the mountains.
“The 2015 was not a mega earthquake, that one is still coming,” warned Surya Narayan Shrestha of the National Society for Earthquake Technology (NSET) in an interview with Nepali Times on Nepal’s Earthquake Safety Day on 15 January this year.
Written records in monasteries in western Tibet chronicle a big earthquake at 6AM on 1 June 1505, and that could have been the last big one that shook western Nepal. Estimated at 8.9, there are also historical records in Moghul India of destruction in Agra and other cities at the time.
The 2015 earthquake was epicentred in Gorkha and did not affect the western half of Nepal. The region is at added risk because of the danger of another big one, as well as because of poorly constructed buildings and lower awareness about earthquake safety.
Friday’s earthquake brought down many buildings made of stone and mud mortar in Jajarkot and West Rukum, and although it hit a relatively sparsely populated region of Nepal the casualty rate was high because it struck at night when families were asleep at home.
Mobile phone images from the affected areas show that even concrete buildings collapsed in the market towns, indicating the severe intensity of shaking. Because of the outmigration of young men from western Nepal to work in India or abroad, most of the casualties are said to be women, children and the elderly.
Nalgad municipality in Jajarkot is said to be the worst affected village, where the deputy mayor Sarita Singh was killed when her home collapsed. Many of the roads leading to these two remote districts are blocked by rockfalls, and there is also reported to be a heavy loss of livestock.
Many of the injured are in hospitals in Chaurjhari and Rukumkot, and those more badly injured are being referred to hospitals in Surkhet and Nepalganj.
Two Nepal Army helicopters have flown to the affected regions from Surkhet early morning on Saturday with relief material, as well as to ferry the injured. Prime Minister Pushpa Kamal Dahal is due to fly out in another helicopter from Kathmandu.