The National Center for Seismology has deployed additional earthquake recording instruments for close monitoring of seismic activity in and around Delhi as the region witnessed a series of tremors last year, the Ministry of Earth Sciences said on Wednesday. Based on the analysis of satellite imageries, the signatures of active faults have been observed at various locations like Wazirabad, Timarpur and Kamla Nehru Ridge in Delhi; Jhunjhunu and Alwar district of Rajasthan; Sonipat, Gurgaon, Rohtak, Rewari and Nuh districts in Haryana; and Baghpat district in Uttar Pradesh.
The geological field survey at all of these sites has been undertaken to validate the identified features from the satellite data. The analysis pertaining to the correlation and interpretation of field evidence and satellite data is in progress. This information and the results generated through magnetotelluric (MT) surveys can be utilised for the future seismic-resistant buildings, the MoES said.
The NCS had consulted with a few experts and it decided to deploy additional recording instruments for close monitoring of earthquake activity in and around Delhi, and to carry out field studies to characterise the subsurface structures using geophysical techniques, the MoES said.
The MT geophysical survey, which involves measurement of the time-varying electric and magnetic fields to determine the distribution of electrical conductivity in the subsurface, has been carried out in collaboration with the Wadia Institute of Himalayan Geology, Dehradun, across the Moradabad Fault (in Moradabad and its surrounding area) and Great Boundary Fault (in the Bareilly and its surrounding area).
The MT survey has been completed across major faults of the Delhi region, such as the Mahendragarh-Dehradun Fault, Sohna Fault, Mathura Fault, Moradabad Fault and the Great Boundary Fault, it said. The data analysis is in progress. Active fault mapping is another study that has been taken up jointly with the IIT Kanpur, it said.
The National Capital Region and its surroundings had experienced minor and small-magnitude earthquakes since last April. The epicentre of these earthquakes were located in areas of northeast Delhi, Rohtak, Sonipat, Baghpat, Faridabad and Alwar. The NCS has taken up the earthquake monitoring through 11 additional temporary field stations, which were installed during May and June 2020, for precisely locating the earthquakes for a better understanding of the causative sources.
All these stations are operational and providing data in near real-time for locating earthquakes. In the past three months, nine earthquakes occurred with a magnitude between 1.8 and 2.9, and are located mostly in west Delhi, southwest Delhi, Rohtak, Sonipat, Baghpat, Bahadurgarh and Ghaziabad regions.
