What caused the earthquake on Monday?

‘Weak zones’, water channels deep inside the Earth and area’s geography caused the tremors, experts say

- Jayashree Nandi

NEW DELHI: The magnitude 4.0 earthquake that jolted Delhi awake early on Monday had its epicentre under the Jheel Park in southwest Delhi's Dhaula Kuan and experts believe the nature of the rocks deep inside the ground roughly 5km, where the temblor originatedhold the key to understanding the unusual occurrence.

A preliminary analysis by National Center for Seismology (NCS) said at fault was a weak zone in the earth's crust, a feature known as "lineament", different and notably, less worrying than a tectonic fault line.

"A lineament is basically a weak zone. These lineaments can become fault lines in future but at the moment it is a weak zone," said OP Mishra, director at NCS.

Mishra added that the origin of the weak zone likely lay in several "paleo water channels and hence porous rocks".

"Hydrostatic fracturing may have occurred. This may have resulted in the earthquake. We can say the earthquake did not occur at the boundary of any fault. Delhi may have historically had these water channels and hence such rocks with pores," he added.