Here’s a fun fact: approximately 1 in 10 people in the world live within 100 km of an active volcano. Aside from causing mass evacuations, destroying huge areas of land, and ruining your travel plans, volcanic eruptions can have devastating health effects. Some research estimates about 540 people are killed by volcanic activity each year. At the moment, there’s no accurate way to predict when a volcano will erupt, but that could change thanks to the work of some Queensland scientists. To understand how this research works, first let’s talk volcanoes 101. Imagine the world like a Ferrero Rocher: a hard crust on top of a viscous mantle with a solid core in the middle (ok, there’s also a liquid inner core but that doesn’t fit with my analogy). Credit: A. Kniesel, Wikimedia CC BY-SA 3.0 The crust is relatively thin, like the skin on an apple, and it is broken up into tectonic plates that sit on the mantle. Volcanoes tend to occur where these tectonic plates meet and either run into each other or move away from each other. Weaknesses in the crust allow molten magma from the mantle to be pushed up, forming a volcano. Within the volcano, magma collects in magma pools, until the build-up of pressure from molten rock and gas forces the magma upwards through weaknesses in the surrounding rock. Eruptions occur when the pressure is so great the magma is pushed to the surface and the volcano explodes, releasing lava, ash and gases. A sudden influx of new magma into existing magma pools can be a trigger for a volcanic eruption. However, since each volcano is different and has complicated pathways from magma pools to the surface, it can be hard to tell how long it will take from a magma influx to an eruption for each individual volcano.
By looking at the chemical composition of tiny crystals and matching this with geophysical and eruption data from the past 40 years, a team of researchers at the University of Queensland has built a model to predict the eruptions of Mt Etna (Sicily, Italy) with a success rate of up to 90%. The crystals grow as magma starts to move up towards the surface of the Earth. The composition of the crystals change depending on their surrounding environment, and grow like tree-rings. By mapping the trace elements within the crystals, the researchers found chromium-rich zones, which suggest crystal growth shortly before eruption, that were surrounded by a chromium-poor ring, indicating surface crystallisation after eruption. By working on the premise that chromium-rich zones indicate the influx of new magma the researchers were able to suggest pathways for the flow of magma through Mt Etna, based on regular eruption events over the past decades. Based on these pathways and seismic data it is possible to predict that Mt Etna will erupt within 2 weeks of a magma influx. The researchers hope to apply this technique to other active volcanoes to better predict when eruptions will occur, allowing early evacuation, saving lives, and not ruining your next trip to Bali.
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March 2018
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