When we talk about Iceland’s volcanoes, we don’t say IF, we say WHEN. The next eruption is always around the corner, occurring on average every three to five years. Grímsvötn is one of Iceland’s most active volcanoes, erupted last in 2011, one year after the infamous Eyjafjallajökull. We tell you why scientists believe that it could happen again soon.
Grimsvötn volcano lies under the Vatnajökull ice cap, Iceland’s largest glacier. Two main volcanic centers lie beneath the ice. Besides Grímsvötn lies Bárðarbunga volcanic center which had the last known eruption in Iceland, in the year 2014-2015.
As we point out in our podcast episode about Iceland’s volcanoes, coming out this Thursday, research shows that right now, the mantle plume is almost directly below Bárðarbunga where the last eruption took place. You can imagine the mantle plume as a large column which rises hundreds of kilometers from deep in the earth mantle.
Color set from green to yellow in September 2020
Activity in Grímsvötn has been growing slowly in recent months. Therefore, the Icelandic Meteorological Office has raised the level of preparedness for flights from green to yellow. When one of Iceland’s volcanoes shows signs of increased activity, the map below will show it.
This color-coding system provides pilots, the general public, and the aviation authorities with information on the state of volcanoes. In the case of Grímsvötn, seismic activity over the past month has been well above average. Geothermal activity increased as well, in addition, measurements show that magma is close to the surface.
Scenario and Indicators
According to patterns seen in past eruption, it is expected that an intense swarm of earthquakes lasting a few hours will signal that magma is moving towards the surface and an eruption is imminent.
Another indicator is a so-called Jökulhlaup (glacier flood). Many of Iceland’s volcanoes lie underneath glaciers. Volcano eruptions in Grímsvötn sometimes happen after the release of a glacier flood. Grímsvötn has a subglacial caldera lake which releases floods on average every 10 years.
With the lowering water levels, the pressure is released, possibly causing an eruption. It could start without a glacier run as a warning but a Jökulhlaup is likely before the actual eruption happens.
Luckily, This area is unpopulated and fully located within the Vatnajökull ice cap. However, Tephra fall can cause complete darkness as far as 100km from the volcano. Additionally, the ash might cause disruption in air and ground transport.
As mentioned above, a Jökulhlaup glacier flood can wash away bridges on road 1 connecting South and East Iceland. Finally, Lava flow which is more unlikely but possible, can reach lowlands and destroy farms, roads, and other buildings.
When an eruption of Iceland’s volcano Grímsvötn starts, we will be the first to let you know. If you love volcanoes and want to know everything about them, tune in to our Podcast this week on Thursday.
Feature image by estivillml on Envato Elements