Iceland: increase in earthquakes

The Icelandic Met Office (IMO) has reported a considerable increase in seismic activity on the Reykjanes Peninsula, with more than 18,500 earthquakes recorded since October 25just north of Grindavík.

• This region, known for its volcanic activity, has seen a substantial increase in both the frequency and magnitude of seismic events, including five earthquakes exceeding magnitude 4 (M4), the strongest being M4.5. A significant uplift of 7 cm was recorded in 10 days at the Mount Þorbjörn GNSS station.

• In the last 24 hours, around 1,300 earthquakes were detected on the Reykjanes Peninsula, including three earthquakes larger than M3. The largest earthquake was M3.6 on the morning of November 6 and was located 3 km northeast of Mount Þorbjörn.

Deformation data shows that uplift continues in the region and GNSS observations indicate increasing rates since November 3.

Since the start of inflation, the uplift at the Mount Þorbjörn GNSS station has reached 7 cm. The deformation is caused by a sill-type intrusion at approximately 5 km depth. Modeling, based on data from October 27, indicates that the volume change associated with this inflation event reached almost twice the volume change associated with the four previous inflation events in the same area between 2020 and 2022 The influx of magma/magmatic fluids into the sill-like body is estimated at approximately 7 m3/s, which is approximately four times higher than the highest influx estimated during previous inflation events.

As inflation continues, seismicity in the region can be expected to increase due to additional stress changes induced within the crust.