Possible eruption at Bárðarbunga

The almost obscenely inconspicious volcano of Bárdarbunga seen in all it’s icy glory.

First of all let me say this, it is only IMO and Almannavarnadeild ríkislögreglustjóra that has the authority to officially declare an eruption in Iceland and issue warnings. Untill they have officially released a warning for an eruption there has been no confirmation.

That being said, below follows what I think is happening currently at Bárðarbunga.

Official warnings

There has so far just been two warnings issued and that is for a potential Jökulhlaup and about a magmatic intrusion. If a medium to large eruption takes place a large Jökulhlaup could burst out and inundate land around the rivers and could be a potential danger to the locals. Here are the warnings issued by Almannavarnadeild ríkislögreglustjóra:

“The National Commissioner of Police and the District Commissioner of Police at Hvolsvöllur and Húsavík have declared a Civil Protection Uncertainty phase due to unrest in Bárðarbunga.”

“Scientists says August 17 at 1000. The earthquakes that began at 3 am yesterday morning continue. The activity has shifted and is now in two clusters, north and east of Bárðarbunga. Scientists believe that the activity is caused by magma activity in the Earth’s crust. No signs yet that the eruption has started. Nothing can be ruled out that the chain of events that is now underway will lead to an eruption outside the glacier or beneath it. Eruptions under glaciers could lead to flooding in the rivers that flow from it. Scientists and the Civil Authorities closely monitor the situation and the uncertainty warning is still valid.”

Earthquakes

Earthquake distribution map from IMO.

The earthquake swarm continues unabated in and around the volcano. It has been noted that the activity is centering on several place and the picture is confusing to put it mildly. So far there have been 853 earthquakes in total with 108 earthquakes between M2 and M3 and 7 earthquakes larger than M3.

The 7 M3+ earthquakes have taken place at different spots, 4 of them is along the Dyngjuháls fissure swarm near Kistufell. 2 are east and east-southeast of Bárðarbunga, and one is a Kverkfjöll. The first four at Dyngjuháls points towards a possible eruption in this area, it is a common spot for Bárðarbunga fissure eruptions.

There are though 3 more earthquake foci, one running ESE from Bárðarbunga, another running towards Kverkfjöll and the third is running from Hamarinn towards Grimsvötn.

Harmonic tremor

Image by IMO, the current seimic and tremor signals at the DYN SIL-station.

So far there is no clear harmonic tremor signal on the SIL-network; there have though been what looks like pulses that could have been gas release in rising magma.

GPS

Hamarinn GPS (HAFS) from Sigrún Hreinsdottirs page. Note the sudden jolt southwards, westwards and up. Click on image for large scale image.

Image from Sigrún Hreinsdottirs page. Notice the rapid jolt northwards. Click on image for large scale image.

I normally say that you need at least 3 data points to be sure of a GPS-trend, and that 5 is preferable. In this case we have 1 data point at two different GPS-stations. Even though it is too little the amount of motion and the direction of motion is of such a dignity that I think it is correct (sanity check).

What they are showing is a magmatic intrusion at depth in or around the central volcano of Bárðarbunga. Dyngjuháls GPS is going in Northerly direction and Hamarinn is being pushed to the south as you can see on the two images.

One thing here is that the GPS points to rapid inflation, and that would mean that as those data points where collected no eruption had started since that would most likely give a more stable signal, or even rapid deflation.

Eye witness reports

There are currently no eyewitness reports or no reports of anything having been spotted during the flyovers.

Guesstimate

At this point I am fairly convinced that an eruption either has started or is about to start. The signs are just a bit too overwhelming right now.

I think that what we will be seeing is an eruption along one of the radial fissures or upwards through the Dyngjuháls main fissure swarm of Bárðarbunga. There is also a chance that we will see Dyngjuháls and one of the radial fissures erupt simultaneously and there is a possibility that the central volcano also will erupt.

It is rather unlikely, but not completely impossible that the current activity will lead to a larger rifting eruption up in the northern part of the Bárðarbunga fissure swarm (Dyngjuháls). I repeat that this is currently unlikely.

Here is a link to our Bárðarbunga links page where you will find all sorts of goodies about the volcano. The author behind the Volcanocafé Bárðarbunga is Spica. This page will be continuously updated so look there for new material daily.

https://volcanocafe.wordpress.com/info-on-bardarbunga/

CARL