Quake Swarm And Rapid Surface Deformation Continues In Iceland

On Iceland's Reykjanes Peninsula, an ongoing swarm of concentrated temblor activity, coupled with rapid surface inflation is raising the possibility of the first volcanic eruption in nearly two centuries near the famed Blue Lagoon. The area has many geothermal features and is once of Iceland's largest producer of geothermal energy.

According to an article released on January 26th, 2020 on Iceland's Met Office website, "An inflation has been detected since January 21st and is centred just west of Mt. Thorbjorn on Reykjanes peninsula. The inflation is unusually rapid, around 3-4 mm per day and has accumulated to 2 cm to date. It has been detected both on continuous GPS stations and in InSAR images. The inflation is most likely a sign of magma accumulation at a depth of just a few km. If magma accumulation is causing the inflation, the accumulation is very small, with the first volume estimate is around 1 million cubic meters (0,001 km3)."

However, that was then, this is now...

Today's quake sequence now records larger quakes up to magnitude 4.4, with three others measuring 4.0, 3.4 and 3.2. Dozens of smaller magnitude temblors dare occurring at the moment.

Screenshot from Iceland Met Office

Today's activity marks a large increase from the initial activity. While magma accumulation has been confirmed, it is far too soon to say whether this will result in an eruption. The activity after the first rash of quakes subsided significantly in the past few days, but today it has surged with some of the strongest quakes in the sequence to date. 

The town of Grindavik lies near the swarm, as does the Blue Lagoon geothermal pools. If an eruption should occur, it would likely form along a SW-NE trend as a fissure eruption, as is the most common eruption type in this area. The lava would likely resemble a Hawaiian style effusive eruption. The area of activity is related to the Reykjanes volcanic system.

The last confirmed historical eruption in this system was a VEI 3 eruption in March of 1831, with two unconfirmed (VEI 0) eruptions in 1966 and 1970 - although the Smithsonian GVP may consider these to be doubtful. 

The Reykjanes system is part of the Mid-Atlantic rift, a spreading rift between the European and American tectonic plates, of which the entirety of Iceland is a result.