Earthquake Swarm

Earthquake Swarm Latest News

A state of emergency has been declared on Greece’s Santorini and the nearby islands of Ios, Amorgos, and Anafi after a swarm of undersea earthquakes this month.

About Earthquake Swarm

• It occurs when multiple seismic events of comparable intensity strike a small area in relatively quick succession.
• It involves a series of many (sometimes thousands) low-intensity earthquakes without a discernible main shock that can occur over weeks in active geothermal areas.
• When seismic energy piles up inside the Earth and is released in small amounts from certain points, such a series of earthquakes can occur.

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What Causes Swarm Sequences?

• Fluid movement
  • In volcanic environments, this can be fluid released from deeper magma or circulating within active geothermal areas (in volcanic areas such as the Taupō Volcanic Zone).
  • The earthquakes triggered by fluids occur as fault slip on the cracks and faults through which the water is moving.
• Active volcanism
  • Magma movement can also act as the ‘driving mechanism’ for swarms, creating the earthquakes as magma-filled cracks push their way through the Earth’s crust.
  • In such a case the earthquakes commonly occur near the crack tip (ahead of the magma where the crack is starting to open), or off to the side of the crack.
• Slow-slip events
  • A slow-slip event is essentially an earthquake in slow-motion, and typically involves centimetres to tens of centimetres of movement along a fault, over weeks to years.
  • We commonly see slow slip events at the Hikurangi subduction zone, usually at least one or two per year. 

Earthquake Swarm FAQs

Q1: What is the difference between earthquake aftershocks and swarms?

Ans: Aftershocks become less frequent with time, although they can continue for days, weeks, months, or even years for a very large mainshock. A swarm, on the other hand, is a sequence of mostly small earthquakes with no identifiable mainshock.

Q2: Where do most earthquakes occur?

Ans: It occurs along the rim of the Pacific Ocean

Q3: What is an earthquake?

Ans: An earthquake is a violent and abrupt shaking of the ground, caused by movement between tectonic plates along a fault line in the earth’s crust.

Source: TH