A Global Tsunami: How Did the Tonga Tsunami Jump From Ocean to Ocean?

Tsunami Illustration

A tsunami is a series of waves created by the displacement of a significant volume of water in a body of water, often an ocean or a big lake. The photo above is an artist’s concept of a megatsunami.

Scientists explain an unusual tsunami.

A new study published in the journal Nature describes the process that produced and propagated an unusual tsunami following the catastrophic explosion of the Hunga Tonga-Hunga Ha’apai in Tonga in early 2022.

The tsunami that followed the massive eruption of the Hunga Tonga-Hunga Ha’apai volcano on January 15, 2022, is thought by scientists to have been exceptional since it had a worldwide reach, a faster propagation rate, unexpectedly high wave heights, and an unheard-of duration.

Hunga Tonga Erupts

This looping video shows an umbrella cloud generated by the underwater eruption of the Hunga Tonga-Hunga Ha’apai volcano on Jan. 15, 2022. The GOES-17 satellite captured the series of images that also show crescent-shaped shock waves and lightning strikes. Credit: NASA Earth Observatory image by Joshua Stevens using GOES imagery courtesy of NOAA and NESDIS

“The violent explosion of the Hunga Tonga-Hunga Ha’apai volcano in the South Pacific was a source of both noticeable atmospheric waves and an exceptionally fast-traveling global tsunami with minimal dissipation in the far-field. This was the first time that a volcano-triggered tsunami was globally recorded by modern, worldwide dense instrumentation, thus providing a unique opportunity to investigate the role of air-water coupling processes in tsunami generation and propagation” explains Rachid Omira, first author, a researcher at Instituto Dom Luiz, Faculty of Sciences of the University of Lisbon (Portugal).

In this study, the research team looked at satellite, sea-level, and atmospheric data from all over the world and used numerical and analytical models to show that the tsunami was caused by an acoustic-gravity wave that was generated by the volcano explosion and that it traveled several times across the globe. In their conclusions, the scientists provide an exact explanation for the tsunami that was witnessed around the world and make hazard-related recommendations.

“The challenging part of studying the Tonga tsunami was to quantitatively explain all the observed tsunami features that were completely different from those of common tsunamis”, adds Rachid Omira, stating: “A fast-moving atmospheric wave able to excite the ocean surface and pump energy into it was our explanation for this tsunami that “jumped” from an ocean to another and reached the coast of Portugal 10 hours earlier than expected”.

Reference: “Global Tonga tsunami explained by a fast-moving atmospheric source” by R. Omira, R. S. Ramalho, J. Kim, P. J. González, U. Kadri, J. M. Miranda, F. Carrilho, and M. A. Baptista, 13 June 2022, Nature.
DOI: 10.1038/s41586-022-04926-4

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