Dr Robin George Andrews
@SquigglyVolcano
So! We've got another new volcano erupting: this time, it's Mount Aso, in Western Japan. Got questions? Here are some answers. A short thread:
View: https://twitter.com/SquigglyVolcano/status/1450712015564062722?s=20
Mount Aso is a rather epic-size volcano, 24km across. According to the Global Volcanism Program, this often viridian bowl was carved out during four massive explosive eruptions from 300,000 to 90,000 years ago.
View: https://twitter.com/SquigglyVolcano/status/1450712017661317123?s=20
These were huge eruptions. Superheated "avalanches" of ash and noxious gas known as pyroclastic flows, and ashfall, covered vast swaths of the mainland island of Kyushu, on which Aso is situated. It definitely has a very violent history.
It is, today, rather beautiful. Within this bowl, or caldera, you can find 17 individual volcanic cones—the remnants of old eruptions. I've hiked through them, and flown over them. It's quite the sight!
View: https://twitter.com/SquigglyVolcano/status/1450712025819140096?s=20
That peak in those photographs? That's Nakadake, the central-ish pit—and the volcano's active crater. Here's the view from a helicopter.
View: https://twitter.com/SquigglyVolcano/status/1450712031200489473?s=20
Nakadake has been active for ages now—eruptions from this spot have been frequent in the last 12,000 years. Typically, you get plenty of ash being generated and cough-like explosions, where slugs of trapped gas violently pop when they reach the surface.
Most of the time, these eruptions are (by volcanic standards) moderate and short-lived (days/weeks). This area is, for Japan, not densely populated. Although pyroclastic flows coming down the slopes here would be frightening, people are, in general, far enough from harm's way.
I'm not sure exactly when, but in the last couple of hours or so, another of these blasts happened at Nakadake. You can see it on this webcam footage, courtesy of the nearby Aso Volcano Museum.
View: https://twitter.com/SquigglyVolcano/status/1450712037152239616?s=20
The risk, at present, is that more explosions could send volcanic debris into the air and which could land on anyone within an approximately 1km radius. Pyroclastic flows could also bubble over the crater rim and pour downslope.
The authorities have closed the volcano off to the public for this very reason. The hope, too, is that there were no climbers near Nakadake when the explosion took place, but so far there have been no reports of any casualties.
For now, this is one to keep an eye on—nothing grim so far, just the largest active volcano in Japan doing its thing.
I know what you're thinking: La Palma, Iceland, Kīlauea, Aso...why are so many volcanoes erupting at once? What is going on? Answer: nothing. It's a coincidence.
Roughly 20-60 volcanoes are erupting at any one moment in time, but we only notice the ones the general new media show us—and they happen to be the ones near people, i.e. the ones that can cause harm.
And when there is a highly destructive or otherwise threatening eruption near people – like the one in La Palma – other eruptions that would not normally get reported on do get general news coverage because public interest in volcanoes is heightened.
So don't worry, Earth ain't doing anything bizarre right now. It's just blowing off some steam, as it always has done. End!
View: https://twitter.com/SquigglyVolcano/status/1450712059511967746?s=20