Is Iceland entering a new volcanic era?

Scientists think there’s some evidence of a centuries-long periodic pattern or cycle, but aren’t sure what it is or what determines the length of it. The graphic shows the most recent two of the five marked phases are west of the earlier ones, plus some apparent north-east to south-west alignments, but otherwise it’s open to intepretation.
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This week, Iceland woke up to yet another day of fire, as towering fountains of lava lit up the dark morning sky, says BBC News.

This time the evacuated town of Grindavik was spared, but the molten rock still wrought havoc – engulfing a pipe that provides heat and hot water to thousands living in the area and cutting off a road to the Blue Lagoon tourist attraction.

It is the third short-lived eruption on the Reykjanes peninsula since December 2023 and the sixth since 2021. But scientists think this is just the start of a period of volcanic activity that could last for decades or even centuries.

So what is going on?

Iceland is no stranger to volcanoes – it is one of the most volcanically active places in the world.

That is because the country is positioned above a geological hotspot, where plumes of hot material deep within the Earth rise towards the surface.

But Iceland also sits on the boundary between the Eurasian and North America tectonic plates. These plates are very slowly pulling apart from each other, creating a space for hot molten rock – or magma – to flow up.

As the magma builds up underground, the pressure increases until it breaks through the surface in an eruption (at this point the hot rock is called lava).

There are more than 100 volcanoes across Iceland and more than 30 are currently active. But the last time the Reykjanes peninsula saw any lava flow was hundreds of years ago – that may have started as early as the 8th or 9th Century and continued until 1240.

Now the eruptions have started again – but why has there been an 800-year gap?

“Over geological time, the tectonic plates are pulling apart at about the speed that your fingernails grow, so a few centimetres a year,” explains Prof Tamsin Mather, an Earth scientist from the University of Oxford.

“But they don’t seem to smoothly pull apart – they go through these pulses of higher activity. And this is likely what we’re seeing right now in the Reykjanes.”

The rocks in the region can reveal even more about the past – and they show a pattern of periods of quiet lasting around 1,000 years – followed by eruptions that continue for a few centuries.

“There’s evidence for about three of these types of episodes in the last 4,000 years in this area” Prof Mather explains.

“So this is proceeding as expected at the moment. And what we’re expecting is a series of these relatively small, relatively short-lived eruptions over the coming years and decades.”
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So is there a way to predict what will happen in the longer term?

Scientists are looking at a number of different volcanic systems that sit across the peninsula.

“In the last cycle, the first eruptions started in the systems to the east and migrated to the west, with a few fits and starts here and there,” explains Dr Dave McGarvie from Lancaster University.

This time, the first eruptions – which started in 2021 – happened in a system that sits more in the middle of the peninsula.

“That system now just seems to have completely switched off – there’s no clear indication of a gathering of magma beneath it. We don’t know whether that’s temporary or whether it’s a permanent thing and it may never erupt again in this cycle.”

Full article here.