Scientists say they have identified the exact mechanism that caused the exceptional tsunami that spread quickly across the world.
The exceptional event was caused by acoustic-gravity waves triggered by the powerful volcanic blast, which traveled into the atmosphere and across the ocean, according to a new paper.
As the waves converge with each other, energy was pumped into the wave which caused it to grow bigger and travel further.
The largest volcanic eruption of the 21st century took place on January 15, 2022.
It was hundreds of times more powerful than the atomic bomb and was the biggest explosion ever recorded.
The eruption caused both atmospheric disturbances and a fast-traveling tsunami that were recorded around the world.
This event was the first recorded by modern, worldwide dense instrumentation, allowing us to finally understand the mechanism behind these unusual phenomena.
Sound waves travel under the effects of gravity. They can cut through a medium such as the deep ocean or the atmosphere at the speed of sound and are produced by violent sources.
A single AGW can stretch tens or hundreds of kilometers and travel at depths of hundreds or thousands of meters below the ocean surface.
After violent events such as volcanic eruptions and earthquakes, AGWs can travel into the atmosphere.
In an ideal location below the surface, the energy was released into the atmosphere in a mushroom-shape. It was inevitable that AGWs would interact with the water surface.
There was a correlation between the first sign of air disturbance caused by AGWs and the start of a wave in many locations.
The team says that the transfer of energy back into the ocean was caused by a phenomenon called nonlinear resonance, where the AGWs interact with the tsunami they generated.
In the new study, they estimate that the wave traveled 1.5 to 2.5 times faster than a volcano-triggered wave, crossing the Pacific, Atlantic and Indian oceans in less than 20 hours.
The wave was driven by a fast atmospheric source, so it didn't have to travel around the South American land mass. According to Dr. Ramalho, this explains why the wave arrived at the Atlantic shores almost 10 hours before it was supposed to.
We have a chance to study the physical mechanism of formation and amplification of global tsunamis via resonance with acoustic-gravity waves. Dr. Kadri said that the resonance allowed us to move beyond the proof of concept of the mechanism and develop more accurate forecasting models and real-time warning systems.
More information: R. Omira, Global Tonga tsunami explained by a fast-moving atmospheric source, Nature (2022). DOI: 10.1038/s41586-022-04926-4. www.nature.com/articles/s41586-022-04926-4 Journal information: Nature
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