Terrawatch: witnessing a ‘lava shield’ volcano form

Icelanders have been treated to a spectacular geological phenomenon with the Fagradalsfjall eruption

Covid has disrupted many forms of entertainment, but for Icelanders the Earth has stepped in and provided a spectacular Covid-safe show. Just over three months ago a volcano burst into action and its fiery fountains – a 45-minute drive south from Reykjavík – have attracted hundreds of spectators every day since. And for geologists this eruption is turning out to be like nothing they have seen before.

Unlike typical Icelandic volcanoes, the chemistry of the lava from the Fagradalsfjall eruption suggests it is coming from a deep and hot source, probably in the upper mantle, and this, along with its low but steady flow rate, suggests it may build into a “lava shield” volcano – with its low profile making it seem like a soldier’s shield on the ground – the like of which Iceland hasn’t seen for thousands of years. The biggest surprise has been the way the lava chemistry has changed over time, possibly a sign of the volcano adding fresh ingredients to the pot.

“We’ve never been able to sample a volcano like this in real time before and it’s giving us profound insights into how magmatic plumbing systems work,” says John Maclennan, from the University of Cambridge.

How long Fagradalsfjall will continue its performance is anyone’s guess, but building something comparable to one of Iceland’s smaller lava shields will take years to decades at current eruption rates.

Contributor

Kate Ravilious

The GuardianTramp

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