The hidden lives of volcanic plumes provide clues about eruption activity

Abstract

Volcanoes can pave their surroundings with lava, send clouds of hot ash downslope to smother cities, and even generate massive tsunamis. The most recent high-profile eruption on the Canary Islands spawned viral videos of slow, steady folds of smoldering lava enveloping houses and swimming pools. A volcano’s plume, such as this one from the 2009 Sarychev Peak eruption on the Kuril Islands in the Russian Far East, can send long-distance signals that indicate an eruption has occurred. Image credit: NASA/Mike Barratt (photographer). But the perils volcanoes pose aren’t limited to ground level: Their ash plumes threaten aircraft passing overhead, even those flying at cruise altitude. In the case of a sudden and explosive eruption, those clouds of ash—which are in fact small bits of rock—can reach elevations of 10,000 meters in just a few minutes. Despite these impressive displays, volcanic eruptions, especially remote ones situated far away from seismic instruments, can be hard to detect. There are some clues: Plume-induced lightning often betrays the presence of ash clouds once they’ve reached high altitude. But recent studies suggest that a different kind of electrical discharge—one generated near the base of a volcanic plume and nowhere else—could provide researchers with a heads-up that an eruption has commenced. Another analysis hints that other unseen signals, the low-frequency warbles known as infrasound, could help researchers monitor changes in ongoing eruptions that signal danger for people nearby. Dozens of aircraft have had run-ins with plumes of volcanic ash, although none of these encounters has been fatal. One of the most dramatic encounters occurred in December 1989 when KLM flight 867 from Amsterdam ran into an ash cloud as it approached its destination in Anchorage, AK. Ash sandblasted the plane’s windshields; airspeed sensors began to give false readings and then failed. All four engines died; the …