I once again reiterate that it is Icelandic Met Office and Almannavarnadeild ríkislögreglustjóra that has the authority to issue warnings for Iceland in regards of eruptions and jökulhlaups.
For airborne ash advisories it is in the following order London VAAC and IMO that issues advisories. That being said here follows a brief update.
This is the latest advisory issued.
The Police Commissioner in Húsavík and Seyðisfjörður have decided to close and evacuate the area North of Vatnajökull following the seismic activity in Bárðarbunga.
This decision is a safety measure. It cannot be ruled out that the seismic activity in Bárðarbunga could lead to a volcanic eruption. There is no change in the seismic activity at the moment and no sign of an eruption and but experience shows that seismic activity can be on going for a long time with out an erupt…ion going off. This is first and foremost a precautionary action since the evacuation of the area is impossible on a short notice.
In accordance with procedure, the National Commissioner of the Icelandic Police has raised the Civil Protection level to Alert Phase. All roads leading into the area are now closed and the authorities in Húsavík and Seyðisfjörður are evacuating the area North of Vatnajökull.
The Civil Protection Alert Phase is declared; “if threat assessment shows that hazard is increasing, a preventive measure must be taken immediately to secure the safety of those who are in the area. That is done by strengthening response measures in the area, and by taking preventive actions such as evacuation and closing off the area in question. Increased preparedness and warnings are also common in this phase.”
Now let us play with the GPS values. Sadly I am not good at all with plotting so I do things by drawing arrows on maps. In this case I will draw arrows on an image from Google Earth. The values I am taking are from five stations. The stations used are Fjórdungsalda (FJOC, Red), Hamarinn (HAFS, Yellow), Vónarskard (VONC, Green) Dyngjujals (DYNC, Blue) & Grimsvötn (GFUM, Black). There is a slight uplift at all stations except at Grimsvötn that has had 20mm of uplift during this crisis.
NOTE, HAFS HAS CHANGED TRAJECTORY TWO DAYS AGO SO THE ARROW IS CORRECT.
I think that the lack of marked uplift is due to separation of the MAR occurring and that the magma is entering into the opening rifts. As such there is no net increase of pressure causing uplift except at the Grimsvötn central volcano.
Now, trying to interpret the orbits of the various GPS-stations is a bit of a headache. But in the end it follows the plate tectonics quite well. The side to the west of the MAR is moving northwards and the eastern side is moving southwards. The division seems to be either along the Veidivötn fissure swarm, or in between Veidivötn and Grimsvötn fissure swarms. The orbit of Dyngjuháls is most likely influenced to go strongly to the east by a local intrusion south of Kistufell. There is no evidence of inflation in Bárdarbunga.
Now for the two arrows that seems to be at odds with each other. Well, Vónarskard is south of the rift zone where the Western arm of the MAR meets the triple junction at Bárdarbunga. From the south comes the South Icelandic Volcanic Zone and then the main MAR goes up north. The plate on the map that is in the southwest is called the Hréppar micro-plate and it seems to be moving east while the part north of the Hréppar is moving to the west.
No wonder we are seeing such a seismic event. Iceland is having a really bad week from a tectonic standpoint.
Well, this is normally where I go and ask my brother at arms GeoLurking for a plot that explains things, but he is sadly not feeling well right now. I hope he feels better soon for many good reasons.
Ash seems to be fun
Now, since this is Iceland and a lot of people remember the ash of Eyjafjallajökull halting air travel I am now incorporating a wonderful ash projection by commenter Down Under. Remember that only London VAAC can issue ash advisories. This is the most likely ash trajectory for the 21st from a 10km ash column.
All the wonderful pictures are once again taken by Eggert Norðdahl. I would like to state that Volcanocafé have been granted publishing rights, if any news agency wish to use the images, or wish to come into contact with Eggert Norðdahl for more images of the upcoming eruption, just send an email to us at our Volcanocafé email.