August 18 – Thar She Blows!

Today’s factismal: On average, a volcano erupts somewhere on Earth each week.

If you’ve been reading the news, then you may have seen an article about Cotopaxi, a volcano located near the capital of Equador. Right now, Cotopaxi is shooting plumes of ash seven miles up into the stratosphere and warming up the snow that covers its summit. Of the two, the snow is the more dangerous thing; when snow melts and mixes with volcanic ash, it can create a lahar which can roll downhill at up to 60 mph covering everything in a layer of steaming mud; it was a lahar that buried Pompeii and a lahar that destroyed Martinique.  But, worrisome as that is, the eruption itself is nothing unusual. There are about 1,500 volcanoes scattered across the globe and every week one or another of them erupts.

A fire fountain in Hawai'i (Image courtesy USGS)

A fire fountain in Hawai’i
(Image courtesy USGS)

Of course, some of the eruptions last longer than others. (For eruptions lasting longer than four years, seek your geophysicist’s advice.)  Stromboli has erupted at irregular intervals for the past thousand years or so but only for a  month or so each time.  But Mauna Loa has erupted almost continuously for at least 700,000 years. The one thing that eruptions have in common is that they are all different, thanks to the types of magma/lava involved and the location of the volcano. (Remember that it is magma when it is in the Earth and lava when it is on the surface.) A volcano with a hot, thin lava that spews into the air can create a fire fountain like the one at Mauna Loa. A volcano with a thick, cooler lava that erupts under water can create a phreatic explosion that blasts bits of the volcano for miles around, like Tambora did back in 1815. Right now, Cotopaxi looks more like a mini-Tambora than another Mauna Loa, but we never know.

Deception Island in Antarctica is a volcano that last erupted in 1969 (My camera)

Deception Island in Antarctica is a volcano that last erupted in 1969
(My camera)

And that’s why we watch volcanoes – so we can learn more and maybe predict what will happen next. If you’d like to do more than watch, then why not download the myVolcano app from the British Geological survey?
https://www.bgs.ac.uk/myVolcano/

One thought on “August 18 – Thar She Blows!

  1. Pingback: September 8 – How Thai The Moon | Little facts about science

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