Geldingadalsgos Eruption: What Happens Next?

The eruption at Geldingadalsgos is currently closed to visitors on account of higher gas emissions, complicated by worsening weather, demonstrating the ever-changing nature of volcanoes. The current situation raises numerous questions on what’s to come: how long will this eruption go on? What shape could it take?

Þorvaldur Þórðarson, a professor of volcanology and petrology at the University of Iceland, offered his own thoughts on the matter. By his estimates, this eruption could end “tomorrow, after a week, or after a month”. Following this depends on the rate of the lava flow; if it falls below 3m3 per second, it will be likely that the eruption will soon come to an end. As it stands now, lava is pouring out at a rate of 5m3 to 10m3 per second.

There are many examples of this type of fissure eruption in Iceland, the closest one near Fagradalsfjall being Þráinsskjöldur, which erupted about 14,000 years ago. Research has shown that that eruption lasted a few hundred years.

“Now, I’m not saying that this is what we’re facing now there at Fagradalsfjall,” Þorvaldur said. “We’re nowhere near that point. What awaits us now is that this valley, Geldingadalur, needs to fill with lava—and that lava needs to be at least 25 to 30 metres thick—before it pours out of the valley.”

Þorvaldur believes it likely that this eruption will end after some days. It could then erupt again after a week, a month, or a year, and not necessarily at the exact same place.

All this being the case, the best estimates are that this will be a short-lived eruption that will leave behind a lava field, but as with all things related to volcano science, these are still just estimates for the time being.

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