It’s safe to say that the explosive volcanic eruption at Guatemala’s Volcan de Fuego (“volcano of fire”) caught the local population by surprise. Although a second explosive event was briefly cause for concern, it was Sunday’s fire and fury that robbed at least 109 people of their lives, with hundreds more missing and feared dead.
As is increasingly the case, satellite imagery is being used to help humanitarian workers, volcanologists, and other authorities grasp the scale of the disaster. Although enlightening, data freely released by satellite company Digital Globe is proving to be especially devastating: comparing pre- and post-eruption images emphasizes just how powerful and deadly pyroclastic flows can be.
The humanitarian effort there is in full swing, but the search for the missing has been suspended. It’s rather unlikely that anyone else will be found. Entire towns and villages were buried, scorched, and obliterated all at the same time in mere moments, as those clouds of fire charged down the valleys in Fuego’s shadow.
Pyroclastic flows are a type of pyroclastic density current, mixtures of hot ash, lava, gas, and entrained debris that emerge from explosive volcanic activity. In the case of the Fuego eruption on Sunday, it appears that there were a combination of formation mechanisms based on the video footage.
The most obvious was that the explosion generated a sustained column of ash above the vent, launching fresh volcaniclastic products through the sky and into the stratosphere. This spread out over a distance of at least 97 kilometers (60 miles), before raining down on the landscape.
When parts of this column lost upward momentum, however, it fell down to Earth, creating a pyroclastic flow. It’s also possible that some of the less buoyant parts of the eruption column simply “boiled over” at the vent, and rushed straight down the slopes.