An earthquake with a magnitude of 4.7 on the Richter scale hit Alwar district in Rajasthan. Tremors were felt across Delhi. (Source: National Center for Seismology)

Earthquake in Delhi NCR: Tremors were felt in parts of national capital and NCR Friday evening after a medium-intensity earthquake of magnitude 4.7 jolted Alwar district in Rajasthan, the National Centre for Seismology said.  According to the NCS, the quake occurred at 7 p.m. at a depth of 35 kilometres.

Since April, 20 earthquakes have been recorded in and around Delhi. Of the 20, two were above magnitude 4. Recent earthquakes in Delhi have triggered discussions on the possibility of increased seismicity around Delhi, and fears of an impending big earthquake sometime soon. However, none of these apprehensions have any scientific basis.

Scientists are unequivocal in asserting that no unusual seismic activity is taking place around Delhi in the last few months.

Detection of earthquakes, especially those of smaller magnitude, being recorded in an area also depends on the number of seismic recorders installed in that area. The Delhi-NCR has been identified as the second highest seismic hazard zone (Zone IV).

The area around Delhi has the most dense concentration of seismometers anywhere in the country, even more than the Himalayan region which is seismically much more active.

Out of the 115 detectors installed in the country, 16 are in or around Delhi. As a result, even the earthquakes of smaller magnitude, those that are not even felt by most people, are recorded, and this information is publicly accessible.

Earthquakes of magnitude four or below hardly cause any damage anywhere and are mostly inconsequential for practical purposes.

The historical earthquake catalogue shows that there were strong earthquakes in the Delhi-NCR — of 6.5 magnitude at Delhi in 1720; 6.8 at Mathura in 1803; 5.5 near Mathura in 1842; 6.7 near Bulandshahar in 1956; 6 near Faridabad in 1960 and 5.8 near Moradabad in 1966.

(Inputs from PTI)