What’s in the News?

• Recently, a 4.3-magnitude earthquake shook the national capital, causing widespread panic due to its unexpected intensity.

Reason for the Earthquake

• There are two reasons why this 4.3-magnitude earthquake felt particularly strong: Its epicentre and its depth.
  • The epicenter of an earthquake is the point on the Earth’s surface directly above where the earthquake starts underground (the focus). It is where the shaking is usually strongest.
• The epicentre was located well within Delhi, specifically in Dwarka. This proximity was the first reason behind the intensity of the tremor.
• The second reason was that it was a shallow earthquake, occurring just 5 kilometres (km) beneath the surface. Shallow earthquakes tend to feel much stronger because seismic waves have less distance to travel before reaching the surface, resulting in more intense and noticeable shaking.

Causes of frequent shallow Earthquakes in Delhi

• Delhi’s high seismic risk:
  • The city lies in Seismic Zone 4, where earthquakes of magnitude 5 to 6 are fairly common. 
  • The region’s seismic activity is linked to the ongoing collision between the Indian and Eurasian plates, which has been occurring for over 50 million years. 
  •  This collision builds up energy that is periodically released when the plates shift.
• Groundwater extraction:
  • Studies suggest that pumping out groundwater can trigger earthquakes by reducing pressure in the underlying rocks. 
  • Research has shown that Delhi’s seismic activity is influenced by human activities such as irrigation and urbanisation, which impact local aquifers. 
  • A 2020 study found that seismic activity in Delhi fluctuates both annually and over decades, aligning with changes in groundwater levels.