In 2021, a deadly volcano erupted with no warning. Here’s why

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Now, using data from monitoring stations installed near the volcano in 2015, researchers have pieced together how that eruption happened so suddenly. The data also suggest that the event could have been even deadlier — and highlight the urgent need to better understand this volcano’s particular hazards before the next eruption, volcanologist Delphine Smittarello and colleagues report in the Sept. 1 Nature.

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The trigger for the actual eruption was probably a tiny rupture that formed in the volcanic cone due to the buildup of stress over time from the pressure and heat of the magma within, the researchers say. That would have been enough to allow the magma to push through.

The short lag time between the signals and the eruption was probably because that magma was already extremely close to the surface, the researchers suggest. “What we monitor is the magma moving, not the presence or absence of magma,” Smittarello says. Because the magma had very little distance to travel, there was also very little warning.

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Based on the possible path of the magma, Goma city officials issued evacuation orders for tens of thousands of people who were potentially in the magma’s path. Meanwhile, scientists anxiously watched for signs of a potential “limnic eruption” at Lake Kivu — a rare type of disaster in which a noxious cloud of dissolved gases like carbon dioxide and methane suddenly erupts from deep lakes, suffocating living creatures nearby (SN: 4/2/94).

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