Second earthquake in 24 hours jolts Tonga Islands

TONGA ISLANDS: An earthquake of magnitude 6.1 on Richter Scale jolted Tonga Islands on Sunday, with this being a second earthquake in the same day.

The earthquake took place at a shallow depth of 10 km, making it susceptible to aftershocks.

In a post on X, NCS said, “EQ of M: 6.1, On: 30/03/2025 20:34:58 IST, Lat: 20.37 S, Long: 174.16 W, Depth: 10 Km, Location: Tonga Islands.”

EQ of M: 6.1, On: 30/03/2025 20:34:58 IST, Lat: 20.37 S, Long: 174.16 W, Depth: 10 Km, Location: Tonga Islands.
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— National Center for Seismology (@NCS_Earthquake) March 30, 2025

Earlier in the day, an earthquake of 7.0 on the Richter Scale jolted Tonga Islands, a statement by the National Center for Seismology said. As per the NCS, a massive earthquake occurred at a shallow depth of 10km.

In a post on X, the NCS said, “EQ of M: 7.0, On: 30/03/2025 17:48:48 IST, Lat: 20.06 S, Long: 174.04 W, Depth: 10 Km, Location: Tonga Islands.”

EQ of M: 7.0, On: 30/03/2025 17:48:48 IST, Lat: 20.06 S, Long: 174.04 W, Depth: 10 Km, Location: Tonga Islands.
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— National Center for Seismology (@NCS_Earthquake) March 30, 2025

Shallow earthquakes like these are more dangerous than deeper ones due to their greater energy release closer to the Earth’s surface, causing stronger ground shaking and increased damage to structures and casualties, compared to deeper earthquakes, which lose energy as they travel to the surface.

The Tonga Trench is the place where the Pacific and Australian plates meet. The motion of these two plates has created one of the most seismogenic (“earthquake-making”) regions in the world; every year, there are approximately 200 earthquakes near Tonga.

Most of these are very small, but large earthquakes happen about once every decade; great earthquakes (those larger than magnitude 7) happen there about once a century. The effects of these earthquakes can be felt around the world. The energy from the earthquake travels as a sound wave through the Earth and is picked up on seismometers.

This sound wave causes the local rock to change shape (to strain); this change is recorded by strainmeters. And the small changes in position caused by the sound wave are detected on GPS sensors.

Subduction zones have earthquakes because these are places where two plates move against each other. One plate moves under the other (“subducts”), and t slowly bends the overriding plate. This causes both plates to bend; in some cases, this bending can raise volcanoes and atolls above the ocean’s surface, creating new islands. Eventually, the overriding plate slips, creating an earthquake and submerging some of the islands. (ANI)