India has installed more quake-detection equipment, which can capture small seismic activity that went undetected earlier. Reports of tremors have sparked fears of a big quake looming in the seismically vulnerable region, but scientists said there is no established correlation between the two and big quakes may not be preceded by warning tremors.
“Earthquakes cannot be forecasted and some smaller earthquakes do not result in a larger, more destructive one,” said JL Gautam, senior scientist at the National Centre of Seismology (NCS), the country’s nodal agency that monitors the earthquakes.
Gautam said the higher number of recordings of late has been a direct consequence of the lockdown. With no road and rail traffic, which the NCS calls “cultural noise,” observatories are recording vibrations that may have otherwise been difficult to record or go unnoticed entirely.
“We also have more people who have spent all of their time in their homes for the past couple of months. They have thus picked up even the slightest of sounds or movements, creating panic,” said Gautam.
Other scientists agree.
“There is virtually no background noise due to industrial activity or transport right now that could affect the recordings. What we are getting right now are pure readings, without any pollutants – hence the rise in reports of minor earthquakes,” said Laxman Singh Rathore, former director general of the India Meteorological Department. “Pre-lockdown, the small-scale earthquake activity was hidden in the background. We are able to record these better now.”
Before 2000, the NCS only had four stations in New Delhi to record earthquakes. They got nine new observatories in 2000, and today there are 25 stations across the National Capital Region that monitor seismic activity.
“With the rise in observatories, we have noticed a steady increase in the number of earthquakes. Tremors that would have been missed earlier due to lack of coverage are now picked up as well,” said Gautam. “Due to these reasons, we cannot say that the past month, month and half has seen Delhi have more earthquakes than usual.”
Delhi’s categorisation under the seismic zone IV also gave rise to concerns, with the highest level at zone V.
“Although zone IV is at a higher risk, there is no cause for any concern right now. Delhi will be safe,” said Gautam.
The NCS said earthquakes measuring below 5.0 on the Richter scale will not cause any structural damage. All of the NCR’s recent earthquakes have been under that limit, with the strongest, which struck Rohtak on May 29, coming in at 4.5.