Why is Maharashtra experiencing an earthquake swarm? | Explained

There has been a spate of small earthquakes in Maharashtra over the last fortnight, according to local reports. Of the 29 tremors during this period, 24 were in and around Nashik, four were in Palghar and one was in Nagpur. They weren’t particularly strong — the strongest was in Nagpur on August 8, of magnitude 4.3 — although they were also shallow, around 5-8 km deep. Seismologists call this pattern of quakes an earthquake swarm, and Maharashtra has experienced them often before.

An earthquake is a sudden movement of rocks along a fault, i.e. a fracture or a region of weakness in the earth’s crust. In some places, friction can prevent two rock blocks from sliding past each other.