Unusually strong earthquake swarm at Eldey volcano, Aviation Color Code raised to Yellow, Iceland

Shortly before midnight on July 6, 2023, a seismic sequence commenced close to Eldey Island on Reykjanes Ridge, approximately 10 km (6.2 miles) southwest off of Reykjanes Peninsula, Iceland. As a result, the Aviation Color Code was raised to Yellow.

The swarm started just a couple of days after the start of the seismic crisis near Fagradalsfall volcano, Reykjanes Peninsula.

As of 10:29 UTC on July 8, around 500 earthquakes have been detected on Reykjanes Ridge. Around 20 quakes over M3 and 6 over M4 have been detected there, with the largest being M4.5 at 05:06 UTC on July 8.¹

Earthquake sequences in this area are not uncommon but this current activity is unusually high, the Icelandic Met Office (IMO) said. In light of that, the Aviation Color Code, for Eldey volcanic system, was raised to Yellow.

The Eldey volcanic system is located on the northernmost part of the Reykjanes Ridge and is submarine with the exception of Eldey Island and the skerries (small rocky islands) Eldeyjardrangur, Geirfugladrangur, and Geirfuglasker.²

The maximum water depth within the system is about 250 m (820 feet).

Eldey has been moderately active in Holocene time. Its characteristic activity consists of explosive submarine basaltic eruptions. Six small eruptions have been located within this system during the last 1 100 years, the last occurring in 1926 CE (VEI 0).

VEI 4 eruption took place at the volcano in 1211, followed by VEI 3 in 1340, VEI 2 in 1422, and VEI 1 in 1879.

References:

¹ Specialist remark – IMO – July 8, 2023 at 10:29 UTC

² Eldey – Geological summary – GVP

Featured image: Earthquakes detected at Eldey volcanic system from July 6 to 8, 2023. Credit: IMO