Yesterday (31. January 2020) a strong earthquake swarm started north-east of Grindavík village. This earthquake swarm lasted only around 12 hours but it made over 800 earthquakes in this time. The activity was so high it was too much for the SIL network and that resulted in a lot of ghost earthquakes all over Iceland. Largest earthquakes in this swarm had a magnitude of Mw4,3 and Mw4,0. There were 8 to 9 earthquakes with magnitude larger than Mw3,0.
The earthquake swarm north and north-east of Grindavík town. Copyright of this image belongs to Icelandic Met Office.
Higher resolution map of this earthquake activity from this website here (Icelandic Met Office).
Earthquake activity in the area of Grindavík town for the last 7 days. Copyright of this image belongs to Icelandic Met Office.
GPS inflation data shows that there has not been a lot of change in the last 24 hours. The GPS inflation data can be viewed here (I don’t have permission to post those images to my website). Inflation is still ongoing and that is going to result in more earthquake swarm activity in this area and nearby areas.
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Strongest reading of the day on the early alerts. It’s nothing big, maybe a M2.5. Looks like the swarm the other day released some stress.
Nono, wrong. It was a M3.0 further out on the Ridge.
http://hraun.vedur.is/ja/oroi/grv.gif
Tremor there?
Was there any damage to the Geothermal Plant directly over the area of swarm?
What concerns me most is the proximity to the international airport. There is a small domestic airport in Reykjavik but it can’t handle the large planes. The major airport is in Keflavik (Reykjanesbaer) which appears to be only 20 km or so from this activity.