Category: Earthquakes

Here is a picture of a earthquake that took place in Askja volcano last night. This earthquake was bearly visable on my geophone close to Hekla volcano. From this data it is clear that the earthquakes are created by magma movements inside Askja volcano. But the earthquake swarm is taking place on the edge of Askja volcano main system. It is not happening outside as it might appear.

It is also worth pointing out that not all of Askja volcano earthquakes might appear on the automatic SIL system. But most of them should do so. As Askja volcano is remote and in a unpopulated area there should not be any damage from a eruption. The only damage might happen if there is a eruption in Askja caldera lake due to ash cloud that might form.

Askja volcano earthquake. This is low pass filtered at 1Hz. This image is released under Creative Commons License, see top link for more information. Click on this picture for full resolution.

This earthquake has magma signature from the looks of the earthquake signal. But due to distance it is hard to be sure on that.

When this is written a tremor pulse appears to be starting in Askja volcano. But this might also be a swarm of micro earthquakes taking place in Askja volcano without the earthquakes appearing on the automatic SIL system. At this point it is hard to know for sure, as this activity is new.

Locations of the earthquakes in relations to the Askja volcano system. As can be seen on this map from Icelandic Met Office, the earthquakes are clearly inside Askja volcano. Even if they are not at the main caldera. Picture is from Icelandic Met Office web site. Copyright of this picture belongs to Icelandic Met Office.

Blog post updated at 16:37 UTC on 5 May 2011. Picture is added.

The earthquake activity in Askja volcano continues to evolve at rather fast phase. A lot faster phase then I did originally expect. Far as I can tell from the Icelandic Met Office SIL data (tremor plots). The earthquakes that are now taking place in north Askja volcano appear to be mostly magma related earthquakes. The strongest earthquake so far did happen today and had the size ML2.5 with the depth of 0.1 km. The deepest earthquake so far took also place today and had the depth of 19,6 km. It had the size ML1.4.

However earthquakes with the depth of 22 km has been recorded close to Herðubreiðartögl. Few days ago a tornillo earthquakes (most likely the case now. But yet unconfirmed from my point of view) started too appear in Askja volcano. But that means that magma is on the move in Askja volcano. Currently this might also be the case with the earthquake activity east of Askja volcano. But at this moment it is a bit more unclear what the activity east of Askja volcano means. But it is also possible that magma is also pushing east from Askja volcano. But so far earthquake activity east of Askja volcano has been different then from the earthquake activity north of Askja volcano. But it has not been focuesed on a single spot like the earthquake activity in north part of Askja volcano system.

It is unclear at this moment how this is going to evolve in the long term. But no reports of increased hydrothermal activity have so far appeared in the news. Currently the activity is rather low, so a eruption is not yet imminent in Askja volcano. But that might change without any warning at all at any time.

Current Askja volcano earthquake activity. Click on this picture for full resolution. Picture is from Icelandic Met Office web site. Copyright of this picture belongs too them.

Due to distance. I do not record any small earthquakes from Askja volcano. But they need to be larger then ML3.0 to appear on my geophone network.

This is just a short overview of the Askja volcano earthquakes that have been taking place over the past few weeks. I do not at this have a good picture of what is happening in Askja volcano.

In Week 15 earthquake activity started north of Askja volcano. This activity have been growing since then, with considerable difference between Week 16 and Week 17. Currently the earthquake activity is ongoing. It is not clear if this earthquake activity has slowed down or not. Many of the earthquakes that are taking place north of Askja volcano are shallow. But most of the earthquakes are happening on a depth from 1 km and up to 0.0 km. I am currently unclear on why the activity is so shallows as seems to be the case.

A second set of earthquakes have also been taking place in Askja volcano system. But this earthquakes are taking place east of main Askja volcano. But Askja volcano fissure system goes east and then north from the main volcano. It also goes several km south of main Askja volcano. But that area has not seen any activity so far. While the activity east of Askja volcano is not clustered as it is north of it. It is showing many of the same signs as the earthquakes north of Askja volcano. They are shallows with most of the earthquakes taking place in less then 1 km depth. As before I am not sure why the earthquakes are taking place on less then 1 km depth. But one idea for both the earthquakes north and east of Askja volcano is that there is magma pushing up the bedrock north and east of Askja volcano. But does not at this time have the power to break up trough the crust and start a eruption. Only one deep earthquake has so far been recored, it was on a 22,8 km depth. The location of this earthquake was not far from Herðubreiðartöglum mountains.

Due to lack of GPS data it is hard to see any deflation or deformation in Askja volcano. But it has been known since last year (2010) that Askja volcano has started to prepare for a eruption. But it remains unclear how long it is until Askja volcano is fully ready for a eruption. Last eruptions that took place in Askja volcano where in the years 1961, 1938, 1926, 1924, 1923. More on Askja volcano eruption history here (GVP web page).