Reykjanes Earthquake Swarm: Ongoing Geological Activity Causes Road Damage Skip to content

Reykjanes Earthquake Swarm: Ongoing Geological Activity Causes Road Damage

By Gréta Sigríður Einarsdóttir

Photo: Icelandic Road and Coastal Administration.

Since midnight, around 1300 earthquakes were detected in the Reykjanes Peninsula, the largest measuring M3.4 at 8.36 am. The activity was strongest in Fagradalsfjall and east of mt. Þorbjörn. While the seismic activity hasn’t been as strong as it has been for the past few weeks, new InSAR images indicate that the magma dike keeps growing slowly but surely, at a similar depth as before, about 1 km underneath the surface.

The new satellite images indicate that over the past week, the earth’s crust on either side of the dike has been pushed apart by about 20 cm. Geophysicist with the University of Iceland Freysteinn Sigmundsson told RÚV that there was a chance the magma had moved a little closer to the surface, by 100-200 m or so, but they couldn’t be certain. The shifts in the land have caused cracks alongside the nearby road along the south coast of the peninsula. The Icelandic Road and Coastal Administration have put up signs indicating narrower lanes and dropped the speed limits to 50 km per hour in the affected area. Drivers are asked to be careful.

Icelandic Road and Coastal Administration

Scientists still consider Nátthagi, just south of mt. Fagradalsfjall the most likely point of eruption and the Department of Civil Defense and Emergency Response is working on a contingency plan if an eruption were to occur. This includes compiling a list of construction equipment in the area such as excavators and bulldozers that could be used to protect infrastructure in the area such as roads or inhabited areas. They likely wouldn’t risk digging ditches to redirect lava to save roads, as roads are relatively easily reconstructed, but if an eruption threatens powerplants or towns in the area, that’s one option available. During the Vestmannaeyjar eruption in 1973, the local harbour was threatened by the lava flow but was saved by pumping seawater over the lava, so it would cool and harden. If an eruption occurs in Nátthagi, it likely won’t threaten inhabited areas or power plants.

A geophysicist at the Icelandic Met Office Benedikt Ófeigsson told Vísir that there were still clear signs that magma was on the move and that today’s data indicated that the comparative calm today was likely not the end of the Reykjanes Peninsula earthquake swarm.

In Focus: The Geology of the Reykjanes Peninsula

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