Source Icelandic Met Office
Two days ago, in Iceland: Watching Bárðarbunga, I wrote about the swarm of (mostly small) earthquakes close to Iceland’s second tallest volcano, and the raising of the aviation warning status for the volcano to Orange. Monday morning saw the largest quake – an M4.5 – but since then well over a thousand smaller quakes have continued to rumble.
Yesterday, local authorities – out of an abundance of caution - ordered the evacuation of large areas north of the volcano (see Icelandic Review Alert: Area North of Bárðarbunga Volcano Evacuated), although there are currently no signs of an eruption from the glacier-covered volcano.
While the kind of constant low-level rumbling being detected beneath this volcano often portends an eruption, we’ve seen similar cases where the mountain simply quiets down after a period of time. Even if there is an eruption, it is impossible to know how big of an event it will be.
Nevertheless, Europe and the airline industry – both which was severely impacted by the eruption of Eyjafjallajökull in 2010 – are monitoring these seismic events carefully.
The latest update from the Icelandic Met Office was written last night.
Around 1.000 small earthquakes were detected in the Bárðarbunga region from midnight (18/19) until Tuesday evening 19th August at 20:00. All of them were smaller than magnitude 3 and most were located in the cluster east of Bárðarbunga.
While the northern cluster close to Kistufell has calmed down significantly following the M4.5 earthquake on early Monday morning, event rates in the eastern cluster are still high. Similar to recent days, two pulses of comparably strong seismic activity have been measured between 04:00 and 08:00 this morning, as well as 16:00 and 18:30 in the afternoon. The cluster east of Bárðarbunga continued to slowly migrate northeastwards today. Events are still located at around 5-12 km depths, no signs of upwards migration has been seen so far.
Below is a summary map of all manually revised earthquakes since the onset of the swarm, which illustrates the migration of earthquake activity during the last days. Earthquakes in the map are colourcoded by time, dark blue dots show the onset of the swarm on Saturday, orange dots Tuesday's events until 19:00, light blue and yellow are the days in between. The time scale is days since the onset of the swarm.
Map by Gunnar B. Guðmundsson, Icelandic Meteorological Office.
The following update – dated August 20th – comes from Iceland’s Civil Protection Agency.
Last night the National Crisis Coordination Centre was fully activated after a decision was taken to evacuate the highlands north of Dyngjujökull (part of Vatnajökull glacier). The area is now closed and has been evacuated. These actions were taken following seismic activity around the Bardarbunga caldera in the last few days. The area that has now been closed is both large in size and unpopulated There are still no signs of eruption but these security measures have been taken since it would not be possible to evacuate the area in time should a sub-glacial outburst flood occur from Vatnajökull as a result of an eruption.
At 03.00 the area had been evacuated. A map of the closed area is available at the website of the Icelandic Road and Coastal Administration: http://www.vegagerdin.is/media/umferd-og-faerd/Halendi.pdf In the northwestern part of Vatnajökull glacier the seismic activity is stable, with the main area being northeast of Bardarbunga. Over 300 earthquakes have been detected since midnight. The strongest event was of the magnitude 3.0. Another event happened inside the Bardarbunga caldera and was of the magnitude 2.7.
Today The Coast guard airplane, TF SIF, will make a surveillance flight over the area with scientists and representatives of the Civil Protection, if weather conditions allow. Police and ISAR units will enforce the closure of the area. The situation will continue to be closely monitored.
While there is little to see right now, three webcams have been placed around the volcano, which will provide live pictures if anything happens on the glacier.