Reykjanes Eruption: Most Lava Flow Beneath the Surface Skip to content

Reykjanes Eruption: Most Lava Flow Beneath the Surface

By Yelena

Photo: Golli. Hikers admiring lava from the Reykjanes eruption.

Most of the lava flowing from the Geldingadalir eruption is below the surface and entirely hidden from view. The main active crater is slowly closing up as lava accumulates and cools around the opening. The eruption seems to be developing into what’s known as a shield volcano, a formation created by lava flowing slowly over a long period. The eruption has become a popular tourist site and authorities have already approved the preparation of a new hiking path as lava is expected to flow across the one currently used by visitors.

The Geldingadalir eruption began on Iceland’s Reykjanes peninsula nearly three months ago on March 19, 2021. Geologists have identified three distinct periods of activity since magma broke the surface. During the first two weeks, the eruption had a steady though slightly diminishing flow that started at around 7-8 cubic metres per second and slowed to 4-5 cubic metres per second. The second period began in April, and was characterised by new vents opening to the north of the first craters and a flow of 5-8 cubic metres per second. The third period encompasses the past seven weeks, during which the lava flow has been emerging from a single, large crater and has increased from 5-8 cubic metres per second to as much as 13.

“Now the crater is closing little by little. Especially this channel, it’s being covered up bit by bit. Then it gushes over and that just adds to the covering,” Þorvaldur Þórðarson, Professor at the University of Iceland’s Institute of Earth Sciences (University of Iceland) told While he refrained from calling the eruption a shield volcano, he did admit that activity was pointing in that direction. “It’s approaching that. It hasn’t quite become one yet but it’s going in the right direction.”

Read More: Long Eruption on Reykjanes Could Form Shield Volcano

New Hiking Path in the Works

Since the eruption began, Search and Rescue crews have been monitoring the area to ensure visitor safety. Authorities have also created temporary parking lots at the site and marked a hiking path. The end of the path is now inaccessible as lava has surrounded what was once the main lookout over the erupting crater. Bogi Adolfsson, director of the Þorbjörn Search and Rescue team in Grindavík says the lava flow is expected to flow over more of the current hiking path and authorities have approved the preparation of a new trail to the eruption which will become the main path.

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