Report By:Nandika Chand
New Delhi:As of late, the Delhi-NCR has been recording a series of tremors, with the region being identified as the second highest seismic hazard zone – Zone IV. The tremors are attributed to strain energy being built up in the region. There is a probability of large to great earthquake with magnitude 6 and more in the highest seismic potential zone V and IV which fall in the entire Himalaya and Delhi-NCR.
Dr Kalachand Sain, Director Wadia Institute of Himalayan Geology, said the tremors cannot be described as the signal of a big event. He explained an earthquake cannot be predicted by any mechanism. “All the earthquakes in Delhi-NCR are due to the release of strain energy, which have been accumulated as a result of northward movement of the Indian plate and its collision with the Eurasian plate, through the fault or weak zones,” Sain said. “The energy can be released through the weak zones and faults in the form of earthquakes ranging from a micro-earthquake defined as per the amount of energy released.”
Small magnitude earthquakes are frequent but large magnitude earthquakes are rare to very rare. Sain said it is the large earthquakes that cause severe damages to structures and properties. “The rupture areas due to large earthquakes show gaps along the Himalayan arc, which have not experienced great earthquakes for a long time, and are identified as the future potential zones for great earthquakes,” he said.
More research is needed for subsurface structures, geometry and disposition of faults and ridges. Experts say structures anchored to bedrock or stiff soils in earthquake prone areas suffer less damage because soft soils do not support the structures’ foundations. As such soil liquefaction studies are to be carried out to know the thickness of soft soils.