Measuring the size of a Tsunami

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How big was the size of the tsunami that hit Tonga last year? A new study led by scientists at the University of Miami and the Khaled bin Sultan Living Oceans Foundation measured the size of the Tongan tsunami and found that it was similar in size to the one caused by the eruption of Krakatoa in 1883.

The 2022 eruption of a submarine volcano in Tonga was more powerful than the largest U.S. nuclear explosion, according to a new study led by scientists at the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science and the Khaled bin Sultan Living Oceans Foundation.  

The 15-megaton volcanic explosion from Hunga Tonga-Hunga Ha’apai, one of the largest natural explosions in more than a century, generated a mega-tsunami with waves up to 45-meters high (148 feet) along the coast of Tonga’s Tofua Island and waves up to 17 meters (56 feet) on Tongatapu, the country’s most populated island.

In a new analysis in Science Advances, researchers used a combination of before-and-after satellite imagery, drone mapping, field observations collected by scientists at The University of Auckland, and high-resolution bathymetric maps from the Khaled bin Sultan Living Oceans Foundation’s Global Reef Expedition, to produce a tsunami simulation of the Tongan Archipelago. The results showed how the complex shallow bathymetry in the region acted as a low-velocity wave trap, capturing a more than hour-long tsunami with waves up to 85 meters (279 feet) high one minute after the initial explosion.