A Year Later, the Tongan Eruption is Still Exercising

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A year ago, Larry Paxton was looking at the edge of the field when he saw something he shouldn’t. A physicist at Johns Hopkins University in Maryland, Paxton uses satellite-based instruments that look at the surface of the atmosphere. They see with a range of radiation that we cannot, such as distant X-rays, to monitor things like the weather in an unusual place. But towards the end of January, his team noticed something unusual during the inspection: part of the map was blacked out. The rays of far UV light were absorbed by molecules of some kind, creating a haze almost the size of Montana.

Before long, the source became clear: the Hunga Tonga–Hunga Ha’apai volcano, which had recently erupted in the South Pacific. Those molecules—enough water, Paxton’s team later determined, to fill 100 Olympic swimming pools—were hurled through the air at supersonic speeds in an explosion unlike anything else. which has ever been recorded on Earth. “That’s a huge amount of water that can be pumped up that high,” said Paxton, who presented his research a few weeks ago at the American Geophysical Union. “It’s extraordinary.”

A year later, scientists studying almost every part of the Earth, from the mantle to the oceans to the ionosphere, had the same time as Paxton, who surprised by another wonderful discovery produced by the eruption of Hunga. In recent months, scientists have seen new seismic waves around the world, which have caused tsunamis in distant oceans, and witnessed the largest lightning strike ever recorded. The new cosmic water molecules represented the upper part of the upper atmosphere that was filled with enough water to trap the heat below, possibly warming the Earth slightly in the next few years, according to Holger Vömel, scientist at the National Atmospheric Institute. Research.

The explosion on January 15, 2022 was clearly a surprise. But now the researchers ask: how much unity was it? The answer has implications for the hundreds of underwater volcanoes that line the Earth’s oceans. Shane Cronin, a volcanologist at the University of Auckland in New Zealand, says: “Hunga’s eruption highlights a new type of volcano, and a new type of hazard. underwater. However, only a few underwater volcanoes have been the site of extensive research. These include Axial Seamount, located a few hundred kilometers off the coast of Oregon and studied since the 1970s, and the long-lived Kick ’em Jenny near the Caribbean country of Grenada. Both are regularly visited by research missions and covered by sensors that detect sound waves.

But many more are found in remote areas of the Pacific, far from major cities or harbors where research ships dock. Their closest neighbors are small island nations, such as Tonga, which do not have dedicated volcanology programs or extensive seismic monitoring capabilities. This is due to space constraints. Tonga, for example, is a chain of islands, which is not ideal for gathering three sources of seismic waves—and manpower and capital can be scarce in countries with a population the size of a large United States city. There are international options, such as the US Geological Survey (USGS) seismic monitoring network, which provides global coverage for unusual geological activity, but stations often they’re too faint and too far away to hear the faint sound that foretells an upcoming undersea eruption, Jake says. Lowenstern, director of the Volcano Disaster Relief Program at the USGS.

The magnitude of the eruption is unlikely to match the Hunga Tonga eruption. But this event awakened the world to the possible activity of these volcanoes, says Sharon Walker, an oceanographer at the Pacific Marine Environmental Laboratory. He says: “Although events like this do not happen often, my opinion is that we do not want them to happen on our watches.

It is clear that Hunga included a rare explosive recipe that may not be easily replicated. For about a month, the eruption had continued as expected—moderately violent, with gas and ash, but manageable. Then everything went sideways. That appears to be the result of at least two factors, Cronin says. One was the mixing of magma sources with slightly different chemical compositions below. As these interacted, they produced gases, increasing the volume of magma within the rocks. Under the pressure, the rocks above began to crack, allowing cold seawater to enter. There were huge explosions—two of them actually—that blasted billions of tons of material directly into the upper part of the valley, some of it apparently into the sky.

Both explosions produced large tsunamis. But the biggest wave came later—a wave that may have been caused, Cronin thinks, by water flowing from a mile-deep hole suddenly dug into the ocean floor. He says: “That’s a very new thing for us—a new threat that we can think about in other places. In the past, scientists thought that this type of volcano could only produce a large tsunami if the side of the caldera collapsed. The bottom line, he says, is that underwater volcanoes are very diverse, and sometimes they can behave in more extreme ways than anyone imagined.

But the process of combining volcanic eruptions has also highlighted the challenges of studying underwater volcanoes. A typical mapping expedition will involve a large, fully manned vessel equipped with multibeam sonar that maps the surface of the ocean for changes and a battery of underwater instruments that look for signals. continuous process chemicals. But traveling by boat in the zone is dangerous—not so much because the volcano might erupt, but because the bursting gas bubbles might sink the boat. In Tonga, researchers solved the problem with small boats and a private boat.

Even Tonga, which has been visited four times in the past year because of an influx of research funding to groups studying volcanoes, is unlikely to get another major worker job in years. the next few, Cronin says. The cost is very high. It can take decades to fully monitor each volcano, even those in the Tongan arc. This is a shame, Walker says, because those types of trips are one of the few ways scientists get close enough to see how volcanoes work. The ideal scenario would include more funding for those missions, as well as investments in developing new technology, such as autonomous ships, which can be tricky to operate in the treacherous open sea.

Besides them, scientists are watching from afar. It’s hard to do this when you’re trying to watch underwater scenes – but it’s not impossible. Satellite technology can detect features known as pumice rafts—slabs of volcanic rock that float to the surface—as well as algal blooms, which are maintained by minerals produced by volcanic eruptions. hot. And the USGS, along with their Australian colleagues, are in the process of installing a network of sensors around Tonga that can better detect volcanic activity, linking seismic stations equipped with audio equipment and webcams that watch the explosion in action. Ensuring that it remains operational will be a challenge, Lowenstern says – a matter of keeping systems connected to data and power sources and ensuring Tonga is able to operate the facilities. He adds that Tonga is one of the many countries in the Pacific that could use the aid. But it’s a start.

One of the benefits of studying the Hunga volcano closely is that researchers have noticed new features of the eruption. Over the next few years, Cronin foresees a way to identify which volcanoes need more attention. On their final trip to Hunga in 2022, Cronin’s team used time on board to visit two other underwater sites in the area, including one 160 kilometers away. north with a mesa-like topography similar to Hunga before its eruption. The maps will form the basis of future underwater research, a way for researchers to find out how much is going on under the ocean and reefs. So far, Cronin reports, the sea has been calm.