81 cities added to India’s earthquake-prone list [Disaster Management]
Eight new cities and towns have been added to a government list of urban areas vulnerable to earthquakes of "very severe intensity", even as temblor ripped through India's northeast and the north.
In all, 81 new towns and cities were added to a list of areas prone to earthquakes, bringing the total to 107.
In 2002, only Guwahati and Srinagar were marked in what is called a "very severe intensity zone", or zone V, the highest-risk seismic zone. The recent additions are Jorhat, Sadiya and Tezpur in Assam, Bhuj in Gujarat, Darbhanga in Bihar, Imphal in Manipur, Kohima in Nagaland and Mandi in Himachal. The entire north-east region lies in seismic zone V.
Nearly 60 per cent of the sub-continental landmass is vulnerable to earthquakes, noting 38 earthquake prone cities (with over half a million population in seismic zones III, IV and V), based on 2002 data from the National Disaster Management Authority.
A big Himalayan earthquake-more than 500 years overdue-is expected, although no one can predict when this might be.
The Himalayas and north India are on particularly shaky ground. Sometime in the geological past, before humans, India broke off from an ancient supercontinent called Gondwana (a name still used for what is now Chhattisgarh).
The Indian and Eurasian plates-as sections of the earth's crust that bear the continents are called- have been in conflict for 50 million years at this collision zone, with the Indian plate diving, northward, under the Eurasian plate. This is why the Himalayas, including Mount Everest are still growing.
As many as 392 earthquakes of magnitude greater than three were located in and around India in 2015.
An analysis of the past 30 years of earthquake data suggests that there is no increase or decrease in seismicity rate.
A massive earthquake of magnitude 7.9 jolted Nepal in April 2015, killing more than 8,000 people and injuring 20,000.
The only serious earthquake that modern India remembers is the temblor that killed about 20,000 in Gujarat in 2001.
The 2004 tsunami, which resulted from the third-most most severe quake ever recorded, 9.3 on the Richter scale, occurred when the Indian plate slid with greater violence than it normally does under the neighbouring Burma plate, upon which rest the Andaman and Nicobar islands. It caused a 100-km-long rupture in the crust, thrusting the seafloor upwards and pushing up masses of water, setting off tsunamis that killed 230,000 people in 14 countries.