Delhi residents report hearing mysterious ‘boom’ sound during earthquake; what caused it?

Many residents in national capital Delhi woke up in panic early on Monday morning as a strong earthquake hit the city and adjoining regions. A loud boom sound was also heard by people when the quake struck. Here’s what caused the mysterious sound.

What was the boom sound?
The earthquake that hit Delhi on Monday had a depth of about 5 kilometers, according to the National Centre of Seismology, making it a shallow-focus earthquake. During such quakes, loud rumbling or boom sounds are often heard.

This is because high-frequency ground vibrations from shallow earthquakes reach the atmosphere and become sound waves.

The shallower the earthquake’s epicentre, the greater its potential to generate loud sounds.

“When earthquakes are deeper, those vibrations never reach the surface. Sometimes, earthquakes create booming sounds even when no vibrations are felt,” according to the US Geological Survey (USGS).

Earthquake in Delhi
An earthquake with a magnitude of 4 on the Richter Scale struck Delhi around 5:30 am on Monday. The epicentre of the quake was Jheel Park in Dhaula Kuan area, according to the National Center for Seismology.

An earthquake below 2.5 magnitude is considered “mild” and does not cause tremors. A quake with magnitude between 2.5 and 5.4 is labeled “moderate,” causing minor tremors. Those above 5.4 magnitude are considered “severe” earthquakes and have the potential to cause strong tremors and damage.

Delhi is described by experts as being at moderate to high risk of experiencing earthquakes.