Geolympics 6: Volcanoes and volcanic products

Geolympics 6: Volcanoes and volcanic products

03/09/2019 Perigeo 0
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Volcanoes are one of the most spectacular landforms and eruptions one of the most powerful natural events.

Volcanologists recognize two different types of eruptions: effusive, in which lava steadily flows out of a volcano; and explosive, much more violent and rapid.

Figure 1: Effusive vs explosive. A curling stone slips on the curling sheet – by the way, it is made of granite and weights almost 20 kg! Javelin throw world record is over 72 m.

Explosive eruptions are measured through the Volcanic Explosivity Index (VEI), which is based on the volume of products, height and distance of the produced cloud. VEI is based on a logarithmic scale, which means that an increase of 1 in VEI corresponds to a ten-fold powerful eruption.

For instance, the Mt. St. Helens eruption in 1980 had a VEI 5, the Vesuvius in 79 AD had a VEI 6, Tambora in 1815 had a VEI 7 and produced about 150 km3 of material.

Figure 2: table tennis balls and shot put.

Do you know that you need almost 3000 table tennis balls to reach the over 7 kg of a regular shot or hammer used in track and field? Here’s a comparison of volumes and weights of balls used in different sports.

Volcanic pumice can be occasionally produced by underwater eruptions and float in the ocean. This is what happened few weeks ago (August 2019) near Tonga.

Figure 4: pumice raft produced by an underwater eruption sailing the ocean near Tonga. Contain modified Sentinel-2 image processed through EoBrowser.

Interested in further reading on curling and volcanoes? Take a look here!

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