Tiny crystals of clinopyroxenes that form deep in volcanoes may be the key for advance warnings before volcanic eruptions, according to a team of vulcanologists from the University of Queensland, Australia, and Trinity College Dublin, Ireland.
Mount Etna, with Catania in the foreground. Image credit: Ben Aveling / CC BY-SA 4.0.
“Our research provided new information that could lead to more effective evacuations and warning communications,” said University of Queensland vulcanologist Dr. Teresa Ubide.
“This could signal good news for the almost one in 10 people around the world who live within 100 km of an active volcano.”
Dr. Ubide and her colleague, Professor Balz Kamber, tracked eruptions, their triggers and time scales at Mount Etna, on Sicily in Italy, Europe’s most active volcano.
They used a new laser technique to examine the composition of tiny clinopyroxene crystals forming deep in the volcano.
And what they discovered is that the crystals contain a memory in the form of growth layers that look similar to tree rings.
Reading the history from these layers may lead to more effective volcanic hazard monitoring, including for dormant volcanoes.
“The crystals are created when molten rock — magma — from up to 30 km beneath a volcano starts to move upwards towards the Earth’s surface,” the researchers explained.
“They are carried in the erupting magma, and they often continue to grow as they are being transported. Importantly, they also change in composition on their way to the surface.”
“They effectively ‘record’ the processes that happen deep in the volcano right before the eruption starts,” Dr. Ubide noted.
“We’ve found by studying these crystals in a specific volcano that, when new magma arrives at depth, up to 90% of the time it can trigger an eruption, and within only two weeks.”
From this, the vulcanologists hope to work out how to better monitor volcanoes — for instance, at what depths underground to look for signs of magma movement before an eruption.
“It was currently very difficult to predict volcanic eruptions — as evidenced by the eruption at Mount Agung in Bali, which started last November after two months of precursory earthquakes,” Dr. Ubide said.
“The Bali eruption led to the evacuation of more than 70,000 people and caused massive disruptions in air traffic and tourism, affecting more than 100,000 travelers. Volcanic ash and gas clouds rose to heights of up to 4 km above the summit and produced ash-fall in downwind areas.”
“The results could provide important information for future volcanic monitoring efforts at the site.”
“We plan to apply the same approach to other volcanoes around the world, especially for countries neighboring Australia like Indonesia and New Zealand.”
“The new approach may also prove useful for studying volcanoes that have remained dormant, such as the currently erupting volcano on Kadovar Island, Papua New Guinea,” Professor Kamber said.
“For many volcanoes there is no eruption history, but geologists can collect lavas from past eruptions and study their crystals.”
The findings are published in the journal Nature Communications.
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Teresa Ubide & Balz S. Kamber. 2018. Volcanic crystals as time capsules of eruption history. Nature Communications 9, article number: 326; doi: 10.1038/s41467-017-02274-w
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