Here is why intensity of Delhi’s earthquake felt stronger than magnitude 4.0

An earthquake of 4.0 magnitude on the Richter rocked Delhi in the early hours of Monday, but though the scale was moderate, residents said that the jolts experienced were quite strong, which created panic. The epicentre being closer to the surface than most earthquakes is said to be the reason for this.

The epicentre of the earthquake was recorded to be 5 kms below the Earth’s in the Capital’s Dhaula Kuan locality, which is also home to a large number of military establishments and a stone’s throw away from the Indira Gandhi International Airport and Palam Air Force Station.

“The shallowness of the earthquake is the reason that the intensity felt was more. The more the proximity to the epicentre, the higher is the intensity,” Dr Ashwagosha Ganju, former Director of DRDO’s Defence Geoinformatics Research Establishment, said. “The frequency of shallow earthquakes is significantly higher than intermediate or deep earthquakes,” he added. The epicenters of earthquakes can be over 300 kms deep.

The Dhaula Kuan area, which has a lake nearby, has been experiencing low-magnitude quakes once every two to three years, according to geological reports.

Seismic activity in North India, including the Himalayan belt, he explained, is due to the collision of the Indian tectonic plate with Eurasian tectonic plate, a continuous process happening for the last 50 million years. When stress builds up, the accumulated energy is released in the form of an earthquake.

The National Center for Seismology, which maintains a National Seismological Network of 166 stations across the country, recorded a total of 340 earthquakes in January 2025, out of which 334 were in India and its immediate neighbourhood.

The country is divided into five seismic zones depending upon the risk level, with zone-5 being the highest. Delhi is located in zone 4 which has high seismicity with the general occurrence of earthquakes of 5-6 magnitude, a few of magnitude 6-7 and occasionally of 7-8 magnitude. In the past, five earthquakes of magnitude 5.5 to 6.7 have occurred in Delhi and its vicinity since 1720 AD.

In the Delhi region, seismicity is associated with two major geological structures, the Delhi-Haridwar ridge and the Delhi-Moradabad fault, which have the potential of generating earthquakes up to magnitude 8.

According to the Delhi Disaster Management Authority (DDMA), the city's settlement pattern has never been viewed in relation to geological characteristics. Pockets with high rise buildings or ill-designed high-risk areas exist without specific consideration of earthquake resistance. Similarly, unplanned settlements with sub-standard structures are also prone to heavy damage even in moderate shaking.

DDMA has flagged the central business district of Connaught Place, numerous district centres and sprouting high rise group housing schemes as high-risk areas due to the vertical configurations. The walled city area, the trans-Yamuna area, and scattered pockets of unplanned settlements also figure as high-risk zones due to their substandard structures and high densities.

It has also been pointed out that as far as housing is concerned, vulnerability analysis has never been carried out and preliminary estimate of damages is not available for strengthening of structures under normal improvement development schemes.

Experts say that there are no means to predict the time and place of the occurrence of an earthquake and only general assumptions can be made. At present early warning is limited to sensors that detect tremors generated by an earthquake and generate an alert, providing a forewarning of a few seconds.

This can trigger automatic safety measures like shutdown of power transmissions, halting trains, etc, which help in reducing the extent of damage. The Delhi Rail Metro Corporation, for example, has installed such a system that was developed by the Central Scientific Instruments Organisation (CSIO) in Chandigarh.

“Seismic waves travel at the speed of 4 km per second. If the quake’s epicentre is some distance away, it can provide sufficient time to take certain preventive steps like shutting down sensitive systems or taking shelter,” a CSIO scientist said.

For example, the probability of damage to a stationary train during an earthquake is much lower than to a running one. Similarly a collapsed transmission line or buildings without live electric current will be less dangerous during such incidents, he said.