When the volcano blows

The human-inhabited part of the world dodged a serious bullet in January of 2022, when the colossal Hunga Tonga - Hunga Ha'apai volcanic eruption took place.

Unless you're a geology buff, you might not even remember that it happened, which is kind of astonishing when you consider it.  The undersea eruption created an upward surge of water that was ninety meters tall, twelve kilometers wide, and the wave it generated displaced a volume of 6.6 cubic kilometers.  The tsunami started out nine times as high as the one that devastated Japan in 2011.

After that, a steam explosion -- caused when cold seawater rushed into the collapsed magma chamber after the eruption -- generated an atmospheric pressure wave, producing a second (and faster-moving) set of tsunamis.

The whole thing is hard to talk about without lapsing into superlatives.

The Hunga Tonga - Hunga Ha'apai eruption [Image is in the Public Domain courtesy of NASA]

The fact that this enormous eruption only caused five deaths and ninety million dollars in damage -- compared with the 2011 earthquake and tsunami in Japan, which killed twenty thousand and caused over two hundred billion dollars in damage -- is due to its remote location in the Tonga Archipelago.  Had it occurred closer to heavily-inhabited coastal locations, it could have been catastrophic.

This analysis of the Tonga eruption came out right around the same time as a study out of the University of Cambridge looking at how woefully unprepared we are for a large eruption in a populated area.

"Data gathered from ice cores on the frequency of eruptions over deep time suggests there is a one-in-six chance of a magnitude seven explosion in the next one hundred years. That's a roll of the dice," said study co-author Lara Mani.  "Such gigantic eruptions have caused abrupt climate change and collapse of civilizations in the distant past...  Hundreds of millions of dollars are pumped into asteroid threats every year, yet there is a severe lack of global financing and coordination for volcano preparedness.  This urgently needs to change.  We are completely underestimating the risk to our societies that volcanoes pose."

You might be wondering which are currently considered by volcanologists to be the most potentially dangerous volcanoes in the world.  Generally, these top the list:

• Mount Vesuvius/the Campi Flegrei system in Italy, which destroyed Pompeii in 79 C. E. and threatens the modern city of Naples
• Mount Rainier, southeast of the city of Seattle, Washington
• Novarupta Volcano in Alaska, which could produce climate-changing ash eruptions
• Mount Pinatubo in the Philippines, which has a history of violent eruptions -- and over twenty million people live less than a hundred kilometers from its summit
• Mount Saint Helens -- famous for its 1980 eruption, this volcano has been rebuilding since then and still poses a significant threat
• Mount Agung and Mount Merapi in Indonesia, part of the same volcanic arc that includes Krakatoa
• Mount Fuji in Japan -- scarily close to Tokyo, one of the most densely populated cities in the world

The whole thing is kind of overwhelming to thing about, especially given the question of what we could do about it if we knew a massive eruption was imminent.  Consider the failure of the United States government to act effectively prior to Hurricane Katrina in 2005 -- and there we had several days to do something, during which meteorologists correctly predicted the massive strengthening that would occur prior to landfall, and knew pretty accurately when and where it would occur.  With a volcanic eruption, generally geologists know one is coming at some point, but the ability to predict how big and exactly when is still speculative at best.

Imagine, for example, the reaction of the three-million-odd residents of Naples and its environs if the scientists said, "You need to evacuate the area, because there's going to be an eruption of some magnitude or another, some time in the next six months."

So the problems inherent in dealing with this threat are obvious, but (says the Mani et al. study), that's no reason to close our eyes to it, or refusing to consider possible solutions that may seem to be outside the box.  "Directly affecting volcanic behavior may seem inconceivable, but so did the deflection of asteroids until the formation of the NASA Planetary Defense Coordination Office in 2016," Mani said.  "The risks of a massive eruption that devastates global society is significant.  The current underinvestment in responding to this risk is simply reckless."

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