March 30, 2019

Since November 2018, hundreds of earthquakes, ranging between 1 and 4.3 on the local magnitude scale, have struck Palghar district, Maharashtra. These earthquake “swarms” have pushed Hyderabad’s National Geophysical Research Institute (NGRI) and Delhi’s National Centre for Seismology (NCS) to install seismometers in the region.


  • Meaning: In an 'earthquake swarms', numerous earthquakes occur locally over an extended period without a clear sequence of foreshocks, main quakes and aftershocks. 

  • Duration: The length of time used to define the swarm itself varies, but may be of the order of days, weeks, or months. Swarms usually end after a few days or months. 

  • Cause: How an earthquake swarm develops over time is just as difficult to predict as earthquakes are in general. Many earthquake swarms occur in regions with complex contiguous fracture systems. They are related to the movement of fluid gases and liquids in the Earth’s crust. 

  • Impact: Only seldom does the strength and number of earthquakes increase over time or do occur single, damaging events.

Source : The Hindu