Story at a glance
- Scientists at NASA have been studying the Polynesian island of Tonga for the past six years.
- When a series of massive volcanic eruptions took place in January, researchers were stunned by how powerful they were.
- In a new analysis, one NASA scientist said the power of the eruption was hundreds of times the equivalent mechanical energy of Hiroshima.
A massive volcano eruption covered the Polynesian island of Tonga in mounds of ashes and now researchers at NASA estimate that the power of the eruption was hundreds of times the equivalent mechanical energy of the Hiroshima nuclear explosion.
An analysis by NASA scientist Jim Garvin and his colleagues found that when a Tonga volcano began erupting in late December 2021 and then violently exploded in mid-January 2022, the amount of energy released by the eruption was equivalent to somewhere between 4 to 18 megatons of TNT.
“That number is based on how much was removed, how resistant the rock was, and how high the eruption cloud was blown into the atmosphere at a range of velocities,” said Garvin.
Garvin along with researchers at Columbia, the Tongan Geological Service and the Sea Education Association had been working together for the past six years to determine how Tonga’s young terrain was eroding from ongoing churn of waves and occasional tropical cyclones.
Researchers noticed a dramatic change in January, where volcanic activity seemed normal but had intermittent explosions of ash, steam and other volcanic gases. These ongoing eruptions were reshaping the landscape and expanding the island through new deposits of ash to the growing volcanic cone.
By early January, Garvin said their data indicated the island had expanded by about 60 percent.
On Jan. 13 and 14, Tonga experienced a series of unusually powerful blasts that sent ash surging into the stratosphere, with Garvin estimating it launched as high as 25 miles in altitude and possibly as high as 50 kilometers. That resulted in nearby Tongan islands being blanketed with ash and triggered destructive tsunami waves.
The effects of Tonga’s eruption were felt widely, as New Zealand’s National Emergency Management System issued an advisory warning of tsunami activity. The National Weather Service also issued a tsunami warning for Honolulu, with the U.S. territory American Samoa potentially at risk.
Garvin said that eruptions like what happened in Tonga may help scientists learn about other planets, like Mars.
“Small volcanic islands, freshly made, evolving rapidly, are windows in the role of surface waters on Mars and how they may have affected similar small volcanic landforms,” said Garvin. “We actually see fields of similar-looking features on Mars in several regions.”
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