It’s clear that Hunga concerned an unusually explosive recipe that might not be simply replicated. For a couple of month, the eruption had progressed as anticipated—reasonably violent, with fuel and ash, however manageable. Then every part went sideways. That seems to be the results of at the least two elements, Cronin says. One was the blending of sources of magma with barely completely different chemical compositions down under. As these interacted, they produced gasses, increasing the amount of the magma throughout the confines of the rock. Under large stress, the rocks above started to crack, permitting the chilly seawater to seep in. “The seawater added the extra spice, if you like,” Cronin says. A large explosion ensued—two of them really—which blew trillions of tons of fabric straight out via the highest of the caldera, a few of it apparently all the best way to area.

Both of these explosions produced large tsunamis. But the most important wave got here later—doubtlessly triggered, Cronin thinks, by water flooding into the kilometer-deep gap abruptly dug out of the seafloor. “That’s something really new for us,” he says—a brand new sort of menace to think about elsewhere. Previously, scientists thought that this type of volcano might solely actually produce a giant tsunami if a facet of a caldera collapsed. The backside line, he says, is that submarine volcanoes are extra various, and in some instances extra able to excessive conduct, than anybody thought. 

But the method of piecing the eruption collectively has additionally highlighted the challenges of finding out submarine volcanoes. A typical mapping expedition will contain a big, totally crewed analysis vessel, outfitted with multibeam sonar that maps the seafloor for modifications and a battery of water sampling devices that seek for chemical indicators of ongoing exercise. But taking a ship over a doubtlessly energetic caldera is dangerous—not a lot as a result of the volcano may blow, however as a result of the fuel bubbles burbling up may trigger a ship to sink. In Tonga, researchers solved that downside with smaller ships and an autonomous vessel. 

Even Tonga, which has been visited 4 instances up to now yr on account of an inflow of analysis funding to teams finding out the eruption, isn’t prone to get one other large crewed mission within the subsequent few years, Cronin says. The price is simply so excessive. It would probably take many years to survey each volcano intimately, even simply these within the Tongan arc. This is a disgrace, Walker says, as a result of these sorts of expeditions are one of many few methods scientists get shut sufficient to really see how volcanoes are behaving. An excellent state of affairs would contain extra funding for these missions, in addition to funding in enhancing new expertise, just like the autonomous vessels, which might be tough to function within the treacherous open ocean. 

Without them, scientists are caught watching from a distance. This is tough to do whenever you’re attempting to look at underwater occasions—however not not possible. Satellite expertise can spot objects often known as pumice rafts—sheets of buoyant volcanic rock that bob on the water’s floor—in addition to algal blooms, that are nurtured by the minerals launched by volcanoes. And the USGS, in addition to counterparts in Australia, are within the course of of putting in a community of sensors round Tonga that may higher detect volcanic exercise, combining seismic stations with sound sensors and webcams that look ahead to energetic explosions. Ensuring it stays up and working might be a problem, Lowenstern says—a matter of maintaining the methods related to knowledge and to energy sources and making certain Tonga can workers the services. He provides that Tonga is only one of many Pacific nations that would use the assistance. But it’s a begin. 

One of the advantages of finding out the Hunga volcano so carefully is that researchers have now recognized new volcanic options to be careful for. Over the following few years, Cronin foresees a technique of figuring out which volcanoes require extra consideration. On their last Hunga voyage of 2022, Cronin’s staff made use of the time on the ship to go to two different submarine volcanoes within the space, together with one about 100 miles north with a mesa-like topography that resembles Hunga earlier than its eruption. The maps might be a baseline for future surveys that handle to get out on the water, a method for researchers to determine how a lot motion is occurring beneath sea and rock. So far, Cronin studies, the ocean is quiet.