Aug 6, 2021 5:00 AM

Even Small Volcanic Eruptions Could Create Global Chaos

Relatively minor meltdowns might destroy underwater cables and disrupt vital industries, scientists say, creating a cascade of economic misery.

In the spring of 2010, Iceland’s Eyjafjallajökull volcano kaboomed, sending a cloud of ash into European airspace. The resulting disruption in air travel (ash + engines = bad) was the largest on the continent since World War II, costing an estimated $5 billion.

And yet, Eyjafjallajökull’s meltdown was moderate, as volcanologists classify it. On the “volcanic explosivity index”—which is based on the volume of ejecta like ash and rock—it was a 4. Compare that to the 1815 eruption of Mount Tambora in Indonesia, which gets a 7: It blasted so much material into the atmosphere that it cooled the planet, leading to widespread crop failures. In the Philippines, Mount Pinatubo’s 1991 eruption was a 6. It cost $740 million in economic impacts (adjusted for inflation), even though it was 100 times bigger than Eyjafjallajökull.

In a new paper published today in the journal Nature Communications, a team of researchers argues that Eyjafjallajökull was a warning, and that smaller eruptions can be perfectly placed to cause outsized civilizational misery. That’s not because they produce many fatalities, but because they can trigger the devastation of valuable infrastructure like undersea cables and shipping channels. (As the world recently learned, just getting a single ship stuck in the Suez Canal is a meltdown in its own right.)

The researchers identified seven main “pinch points,” where critical infrastructure exists alongside active volcanoes with the potential for low-magnitude eruptions. An explosion among any of them could set off devastating cascades of economic effects, just as Eyjafjallajökull mucked up air travel. “I just kept thinking, they're all in the same places—all of these systems converge,” says social volcanologist Lara Mani, of the Centre for the Study of Existential Risk (imagine their water cooler chitchat) at the University of Cambridge, lead author on the new paper. “And that's terrifying. Why has no one mentioned this before?”

One pinch point is in Taiwan, which is home to major manufacturers of computer chips; their critical importance in everything from iPhones to cars has become abundantly clear in the current (non-volcanically-induced) chip shortage. Another is to the south, between Taiwan and the Philippines. The Luzon Strait is loaded with undersea cables, nine of which were severed by underwater landslides following a 2006 earthquake, leading to near-total internet outages. And at the Chinese-Korean pinch point, volcanic ash could disrupt some of the busiest air routes in the world, plus shipping in the Sea of Japan.

In Malaysia, the Strait of Malacca is a pinch point because it is also a critical shipping route, with 40 percent of global trade traversing the route annually. The same goes for another in the Mediterranean region: This area is home to Mount Vesuvius, Santorini, and Campi Flegrei, which all could produce eruptions between a 3 and a 6 on the volcanic explosivity index. The authors note that a volcanically induced tsunami here could break underwater cables, disrupt ports, and seal off the Suez Canal. When a ship got stuck there for a mere six days in March, it cost global trade up to $10 billion. Now, imagine a tsunami taking it offline for even longer.

Thanks to Eyjafjallajökull, we already saw what happens when ash spews over the North Atlantic pinch point. And finally, over in the Pacific Northwest, the threat is volcanic debris that could flow so far it could potentially reach Seattle. The authors note that around 5,600 years ago, Mount Rainier generated a mudflow that traveled over 60 miles to reach Puget Sound and what is now the busy Port of Tacoma. Modeling suggests that if the volcano produced a level 6 eruption today, potential losses could total $7.6 trillion over five years.

“These pinch points represent places of heightened vulnerability—they are places that are critical,” says Mani. “Without them, we're going to really feel severe repercussions.” If you lose undersea cables, you lose the communication that’s vital for a functioning economy. If you lose chip manufacturing facilities, the supply chain for electronics crumbles. If you lose shipping passages, the supply chain further deteriorates for everything.

The authors are not arguing that we should stop worrying about large eruptions, which can be deadly for the people living around them, and can also cause longer-term problems if the ash blots out the sun. And they’re not saying that we now have to worry about each small volcanic outburst. “We're not talking about every single lower-magnitude eruption,” says Mani. “It's a low-magnitude eruption in proximity to a pinch point.”

Volcanologists can predict the probability of an eruption on two timescales. If they sift through data on a volcano’s prior eruptions, they can get a long-term idea of when it might be due for another. They can also monitor current seismic activity for warnings of impending eruptions. By doing both, they can estimate the probability of an eruption happening in, say, the next century, but they can also save lives if they need to call for immediate evacuations.

What volcanologists can’t do is fortify the world’s infrastructure against eruptions large and small. “Scientists can make a forecast, can provide some indication about what is possible,” says University of Naples volcanologist Warner Marzocchi, who studies volcanic threats to society but wasn’t involved in this new paper. “We as scientists may suggest something, but probably we could be very naive, in the sense that we don't have any idea about what is the cost of having a backup, for instance.”

That said, scientists are now building an increasingly sophisticated picture of how economic and supply chain disruption could cascade from the area around the volcano to the rest of the world. “I hope that this kind of paper stimulates volcanologists to take into account the fact that it's not only the local impact of an eruption,” says Marzocchi, “but everything that may happen after that.”