Earthquakes are increasing in northern India: scientists warn large earthquake long over-due
July 11, 2013
INDIA – In last few years, Himachal Pradesh (HP) is witnessing increased frequency of earthquakes up to 5 magnitude on the Richter scale, which has led to the fear of bigger quakes hitting the state in future. While experts are claiming low intensity quakes release seismic energy to avoid bigger earthquakes, unplanned constructions, even on steep hills, has led to fear of widespread destruction if a high magnitude earthquake hits the state. In the past 90 years, 250 quakes of magnitude 4 and more than 60 with a reading of 5 on the Richter scale have rocked HP and adjoining states of Jammu and Kashmir (J&K) and Uttarakhand. On Tuesday, a low intensity earthquake of magnitude 5 had hit Kullu, Chamba and Lahaul-Spiti districts and its epicenter was between J&K and HP. Last month, between June 4 and 6, four low intensity earthquakes had hit the state and epicenter of all the quakes was between Chamba and Lahaul-Spiti. The areas falling in districts Chamba, Kangra, Mandi, Kullu, Hamirpur and Bilaspur are very sensitive as they fall in the very high damage risk seismic zone (Zone V), whereas the rest of the areas falls in high damage risk zone (Zone IV). According to D D Sharma of Himachal Pradesh University, frequent occurrences of low intensity earthquakes are good because they help in releasing the seismic energy and does not allow accumulation of energy, which later results in earthquakes of bigger magnitude and intensity. “It is said that a big earthquake revisits after a gap of 50 years and in Kangra district for last 110 years no major earthquake has occurred.
It was in 1905 when 20,000 people were killed in Kangra so threat of a major earthquake is more in that area,” he added. Sharma said a study had shown that if an earthquake of bigger magnitude takes place in Himachal during night hours, then it would kill 240,000 people while during the morning hour casualty would be around 160,000. An assistant professor of geology at HPU’s regional centre at Dharamshala, Mukta, said that after a major earthquake in 2005, whose epicenter was in Kashmir, Himachal has been witnessing low intensity earthquakes at regular intervals. “Last year in October-November around 7-8 low intensity earthquakes were recorded in Dharamshala and Baijnath areas of Kangra district in a span of 3-4 days,” she said. Massive haphazard constructions in the hill towns of Shimla, Dharamshala, Dalhousie and Kullu have made them prone to natural hazards like earthquake. In Shimla, construction has taken place on steep slopes. An earthquake of 8 or above magnitude can turn the tourist town into rubbles as 14 major localities are situated on an average slope of 35 to 70 degrees with peak population density of 2,000 to 3,000 per hectare, despite the fact that the city falls under seismic zone IV. –The Times of India