Explained | 2,800 Tremors, Volcanic Eruption Fears: What's Happening in Iceland?

Iceland has 33 active volcanic systems, higher than any other European country.

(Photo: Kamran Akhter/The Quint)

Iceland is experiencing a seismic swarm as at least 2,800 tremors were recorded on Sunday, 12 November, in Grindavik, from where around 3,000 residents were evacuated due to the growing threat of a volcanic eruption.

The Nordic island country declared a state of emergency on 10 November after a series of powerful earthquakes rocked its southwestern Reykjanes peninsula.

The threat of a volcanic eruption looms large as it could destroy the town of Grindavik and lead to extensive ash clouds, several experts have warned.

"The head of the national police force has declared a state of emergency for civil defence due to intense seismic activity in Sundhnjukagigar, north of Grindavik," the civil defence authority said in a statement, as per Euronews.

The reputed Blue Lagoon geothermal spa – one of Iceland’s biggest tourist attractions – has also been closed temporarily.

Meanwhile, Dr Evgenia Ilyinskaya, an associate professor at the School of Earth and Environment in the University of Leeds, shared on X (formerly Twitter) that though there have been fewer and smaller earthquakes, "this does not indicate that an eruption is less likely."

But what have the earthquakes got to do with the volcanic eruptions? and why is Iceland prone to these tremors? We explain.

Iceland's Location in Seismic Zone

The earthquakes could be a precursor to a volcanic eruption near Sundhnjukagigar, some three kilometres (1.86 miles) north of Grindavik.

Most earthquakes happen on the border where tectonic plates meet. As per Reykjavík-based travel agency Traveo, Iceland is situated on top of one of these tectonic-plate boundaries called the Mid-Atlantic Ridge (which is a crack in the ocean floor separating the Eurasian and North American tectonic plates).

As the Eurasian and North American plates drift in opposite directions, the country is literally torn apart, causing constant seismic activity, according to Iceland Magazine.

In Iceland, there are two main types of earthquakes:

• Those that are caused by volcanic activity and the movement of magma.

• And those that are caused by the release of tension due to the movement of tectonic plates.

Other types of quakes are usually a result of changes in geothermal activity.

Iceland also has 33 active volcanic systems – the highest number of volcanic systems in Europe.

Three volcanic eruptions have taken place on the Reykjanes peninsula since 2021 (March 2021, August 2022, and July 2023) but the epicentres were not close to heavily populated areas.

In a country inhabited by fewer than 4,00,000 people, “earthquakes are a fact of life” according to Perlan, the National Museum in Iceland.

Most of the earthquakes this year were small in magnitude (between 1.0 to 5.0) and hence, they were not strong enough to cause catastrophic damage.

Is a Volcanic Eruption To Follow in Iceland?

According to the country’s tourism website, Iceland has about 130 volcanoes as the country is located in a region with “abnormally high magma activity." In July 2023, lava began to spill from the Fagradalsfjall volcanic system in the southwestern part of the country.

As magma continues to accumulate underground, the Icelandic Meteorological Office (IMO) has warned of earthquakes of up to 5.5 in magnitude.

IMO experts have also said that a volcanic eruption could last ‘for weeks’ as 30,000 earthquakes have been recorded since seismic activity began three weeks ago.

"Since midnight of 12 November, around 1,000 earthquakes have been recorded within the dike boundaries, and all of them have been below M3.0 in magnitude. The most seismic activity has been from the center of the corridor to the north and south under Grindavík. Most of the earthquakes are at a depth of 3-5 km at the lower part of the magma intrusion."

Icelandic Meteorological Office

Thousands of people have been told to evacuate Grindavik as a precautionary measure. If an eruption takes place in or close to the town, the consequences will be devastating, volcanologist Armann Hoskuldsson warned.

"First of all, there isn’t an ice cap on top and it’s not a stratovolcano so it wouldn’t be an explosive blast of volcanic ash into the atmosphere," Matthew James Roberts, the managing director of the service and research division of the IMO was quoted as saying by The Independent.

“This would be a lava-producing volcanic eruption along a series of fissures and that would be the main hazard," Roberts added.

Iceland experiences 26,000 earthquakes each year on an average, as per Perlan. A large and long fissure has opened up at several places in and around Grindavík due to the magma intrusion, stated the Iceland Monitor.

But for now, the police is reportedly allowing residents to enter defined areas in Grindavik.