At 08:22 on 05 October 2016, a magnitude 3.7 earthquake struck the northern caldera rim of Bárðarbunga, the huge sub-glacial volcano in Vatnajökull glacier in the central highlands. According to scientists at the Icelandic Met Office (IMO) a few aftershocks have been detected so far, the largest magnitude 3.
IMO reports that there are some signs of magma movement into the volcano, as expansion of its magma chamber has been recorded.
The large eruption in Holuhraun lava field, that lasted for 181 days (31st August 2014 to 27th February 2015) was directly connected to subsidence in the centre of Bárðarbunga caldera.
Photo: Egill Aðalsteinsson (Iceland Magazine)
One of the largest volcanic system on the planet
Bárðarbunga is at the centre of a 200 km (124 mile) long volcanic system, one of the largest on the planet.
The 10km (6.2 mile) wide caldera is located underneath a 600 to 850 meter (1,968 to 2,788 ft.) thick ice cap in Vatnajökull glacier.
The Holuhraun eruption was in an ice-free zone about 41 km (25.5 mile) north of the caldera, and it left a new lava covering 85 square km (32.8 sq. miles). For scale, imagine an area roughly 1.5 times larger than Manhattan island covered with new 7 to 30 meters (21–90 feet) thick lava.
Could pose significant challenges for airline travel
The system and fissure swarm of Bárðarbunga has erupted on average once every fifty years, with large eruptions every 250 to 600 years.
The largest known volcanic eruption in Iceland after settlement took place in Bárðarbunga in 1477.
This eruption, which was one of the most powerful eruptions in the past 10,000 years in Iceland.
An eruption in Bárðarbunga could pose significant challenges for airline travel in the Northern hemisphere
1,000 earhquakes last week
According to IMO, just over a thousand earthquakes were detected last week (26 September-2 October 2016) by the national seismic network. An earthquake swarm began in Mýrdalsjökull glacier (home of Katla volcano) early in the week. Over 500 quakes were recorded there, most of them within the Katla caldera. A small earthquake swarm occurred northeast of Grímsey Island off the north coast, with around 60 earthquakes, and under 70 earthquakes were measured in Vatnajökull glacier during the week. In the southern lowlands was also some activity where a swarm was in a cluster just 10 km east of Selfoss town in South Iceland and another 80 earthquakes were detected just west of Fagradalsfjall mountain on Reykjanes peninsula on the southwest corner of the country.
This kind of seismic activity is not unusual in Iceland, although this week was a little more active than the average week. The island lies on the divergent boundary between the Eurasian plate and the North American plate. Iceland is in effect slowly splitting apart along the spreading center between the plates, with the North America plate moving westward from the Eurasia plate. The rate of spreading along the Mid-Atlantic Ridge averages about 2.5 centimeters (1 inch) per year, or 25 kilometers (15.5 miles) in a million years.
The national seismic network
IMO’s automatic monitoring network has been in operation for two decades.
Besides evaluating source function and mechanism information carried from below by micro-earthquakes, it provides near real-time information, that is used as the basis for an alert system.
Implications for ICE2017
Clearly, both Katla and Bárðarbunga volcanoes are now on our “radar”, and have to risk-factored into our planning process.
He hope that we can experience some of this activity first hand, whilst in Iceland next year, especially witnessing red-flowing new lava.
However, we also have to keep in mind the potential risks and changes that may be imposed upon our planned route, especially where roads / areas may be sealed off from general public, due to toxic volcanic gases, ash fallout, meltwater flooding, etc.
The ICE2017 Team will be keeping a close eye on both Katla and Bárðarbunga over the foreseeable future.