The Mechanism That Unleashed Tonga's Record-Breaking Tsunami Has Been Identified

The devastating consequence of a volcanic shockwave that broke records was a wave of up to 15 meters (49 feet) in some places.

The mechanism that may have caused the tsunami to travel so far and with such force is known as acoustic-gravity waves, a type of sound wave that can travel quickly through the ocean or the air.

As the volcanic eruption developed, these AGWs traveled through the water, up into the atmosphere and then out across the waves, giving the resulting wave even more energy.

The event would have traveled further and faster if this had not happened.

This event was the first recorded by modern, worldwide dense instrumentation, allowing us to finally understand the mechanism behind these unusual phenomena.

A combination of data from sea level, the atmosphere, and satellite readings was used to determine the presence of these waves.

The volcanic eruption of Hunga Tonga–Hunga Ha'apai was a huge one, but underwater eruptions aren't usually as big as this one. The scientists believe that the way that AGWs excite the ocean-atmosphere interface was important in producing such dramatic and damaging results.

AGWs are affected by the pull of gravity and can be produced by different types of violent events. The waves can travel hundreds of kilometers or miles in length, and they can travel down thousands of meters or feet under the water, as well as reaching close to the speed of sound in water.

The ideal location for the eruption was below the surface in shallow water, where the energy was released into the atmosphere in a mushroom-shape.

It was inevitable that energetic AGWs would interact with the water surface.

When AGWs interact with the waves they've already created, it's known as nonlinear resonance, and the researchers say this was a factor in transferring energy back into the ocean.

The team estimates that the tsunami traveled 1.5 to 2.5 times faster than a typical volcano-triggered tsunami, and it traveled across the Pacific, Atlantic, and Indian oceans in less than 20 hours.

The wave was able to reach the Caribbean and the Atlantic without going around South America first. We can learn a lot from this event.

Kadri says that the resonance allows us to move beyond the proof of concept of the mechanism and develop more accurate forecasting models and real-time warning systems.

The research was published in a journal.