4.7-magnitude quake in Alwar; tremors in NCR

NEW DELHI: An earthquake of 4.7 magnitude occurred in Alwar, Rajasthan around 7pm on Friday evening. The depth of the earthquake was approximately 35km.

“Its intensity was 4.7, so tremors were felt in Delhi-ncr as well. We are getting details on the faults near the epicentre,” JL Gautam, head (operations), National Center for Seismology, said.

The occurrence of earthquakes of small magnitude in Delhi-ncr do not indicate a bigger earthquake is coming, a recent official statement by the Wadia Institute of Himalayan Geology read.

But the institute also clarified that the vulnerability of a region can be understood from its past seismic activity, the calculation of strain and the mapping of active faults.

Delhi-ncr is in the secondhighest seismic hazard zone (Zone IV) in the country, the institute said.

Sometimes a vulnerable zone remains quiet, experiences earthquakes of small magnitude that do not indicate a bigger earthquake, but they can also receive a sudden jolt by a big earthquake with no warning, the statement read.

There are many weak zones and faults in the Delhi-ncr: Delhi-haridwar ridge, Mahendragarh-dehradun subsurface fault, Moradabad fault, Sohna fault, Great boundary fault, Delhi-sargodha ridge, Yamuna river lineament, Ganga river lineament and others.

Delhi is also vulnerable to earthquakes because of its proximity to the Himalayas. There are many faults, ridges, and lineaments transverse to the Himalayan arc.

A major earthquake in the Himalayan seismic belt may also be a threat to Delhi-ncr, the institute had said.

About 22 earthquakes ranging in magnitude from 1.8 to 4.7 have occurred in and around Delhi-ncr since May 1 till date in the vicinity of the Delhi Aravalli range.