Delhi Residents Report A Loud "Boom" During Earthquake: What Was It?

New Delhi:

A strong earthquake of magnitude 4.0 hit Delhi this morning and the tremors were felt in several adjoining areas of the national capital. According to the National Centre of Seismology, the quake hit at a depth of about 5 km. While there have been no casualties or injuries, residents reported a loud sound for a few seconds when the earthquake hit Delhi.

What was the loud sound?

The loud grumbling sounds during the tremors usually occur during a shallow-focus earthquake. According to the US Geological Survey (USGS), high-frequency vibrations from shallow earthquakes generate a booming sound as the ground vibrates and creates a short-period seismic wave motion that reaches the air and becomes sound waves. The shallower the epicentre, the more energy and sound can be produced.

Sometimes earthquakes can create booming sounds even when no vibrations are felt.