Experts had never seen a glacier move like Kolka before. It seemed like the icy equivalent of a pyroclastic flow of hot gas and rock that gushed out of Vesuvius and flattened Pompeii. Most incredibly of all, Kolka had achieved high speeds on a surface that was inclined an average of only six degrees above the horizontal.

“You’re not talking about a glacier that fell off a mountain peak,” says Stephen Evans, a professor of geological engineering at the University of Waterloo. He studied the Kolka site in person soon after the event. “I walked up [the hillside] without breaking a sweat. Six degrees is almost flat for all intents and purposes.”

Evans and a number of other researchers proposed that the Kolka detachment and avalanche represented a previously unknown form of glacial movement. Most glaciers advance at a dawdling pace, sliding about 10 meters (32 feet) forward per year. At times, though, glaciers can surge for weeks at a time, moving 10 meters per day. Then they usually return to baseline advancement.

The Kolka glacier had become something more—they termed it a glacier-debris flow. It traveled more than 10 meters per second.

Nobody could study any other incidence of this new type of glacier movement, though. Kolka was the only scientifically documented cataclysm of its type, the only glacier-debris flow ever to be researched on-site by glaciologists, and the only sudden collapse ever to be observed before and after by satellite. Though some researchers believe the same Kolka site experienced a similar failure in 1902, science knew of no other incident for sure.

That is no longer the case. This summer, two more glaciers failed not in months, but in minutes—and they did it under the watchful eye of some of the world’s largest satellite constellations.

On July 17, 2016, in Tibet, a Himalayan glacier gave way in a fashion very similar to the Kolka failure. More than 60 million cubic meters of ice and rock plunged out of its bed and spilled into the valley below, eventually stopping in Lake Aru Co. Nine people died, all herders, as did hundreds of sheep and yak. Here as in Russia, ice seems to have given way with little warning and to have achieved high speeds on relatively flat land.

The aftermath was first noticed by Westerners in an image captured by the European Space Agency’s workhorse Earth-observing satellite, Sentinel-2. Evidence soon quickly circulated around the glaciologist community. But Sentinel was not the only satellite to see the Tibetan glacier.

Andreas Kääb, a professor at the University of Oslo, discovered that the constellation of remote-sensing satellites operated by Planet, a San Francisco-based private satellite startup, had also captured the glacier-debris flow. Planet had dozens of images of the Tibetan site, all with a higher spatial resolution than Sentinel-2.