Thursday, February 10, 2011

Icelandic eruptions - no need to panic - yet!

Iceland has reached the MSM again. There is an article in today’s Telegraph about some recent activity on the island that may be the pre-cursor to another, but much larger eruption than that of last year. It turns out (as I discuss later in the post) that this may not be as much of a concern as I initially thought, but it gives me an excuse to update information on what is going on up there.

Last week there were three earthquakes greater than M3 in the region of Bárdarbunga, and there has been a continuation of activity in the region since then. It is, however, quiescent this morning, so that a check on the Iceland Met Office (IMO) site, is showing little activity in the region today. The Icelandic names are fairly long, so I am going to the Norse names of Loki, Laki and Katla for the three major areas where eruptions might be expected. The volcano that erupted under the glacier at Eyjafjallajokull last year does not have such a name, since it is much smaller than the other 3 – in itself a little worrying. The volcano that is now a worry is the one known as Loki. Laki and Katla are also a bit of a concern, and I’ll explain that a little later. Their locations are shown in general on the overall earthquake map where the IMO displays earthquakes.

Map showing earthquake activity in Iceland (IMO)

Loki has erupted in 1910, 1938 and lastly in 1996 and has not been, in general, that severe. The 1910 eruption was evaluated at a Volcano Explosivity Index of 2. There was a smaller eruption (which only affected local air traffic) in 1996 to the East of the current activity. Loki lies under the Vatnajokull glacial cap, which is about half-a-mile thick.

I have been keeping a record of the Icelandic quakes greater than M3 since the eruption at Ejyafyallajokull last year, just to see if there are clear pre-cursors. This is because the eruptions there have often been precursors for the subsequent, much larger eruption at Katla, which is relatively just next door.

The full list of earthquakes in Iceland greater than M3 is at that bottom of this post and I continue to add quakes there as they happen. The IMO site allows you to zoom in (by clicking the mouse at the relevant point) to different zones on the map. And if you do that for the Loki area, then you will get this map.

Map showing the Loki volcano region of Iceland (IMO ) The area in white is the Vatnajokull ice sheet.

Note the locations of Bardarbunga, Hamaninn and Grimfjall. Here are the last quakes: The information is tabulated as date, latitude, longitude, magnitude (depth and location).

81) 01-13-2011
64,400, -17,250, 3,8 (14.4 km deep 1,2 km ESE of Grímsfjall)

82) 01-25-2011
64,514, -17,667, 3,0 (1.1 km deep 97,5 km ENE of Hamarinn)

83) 02-02-2011
64,682, -17,361, 3,1 ( 1.4 km deep 9,2 km ENE of Bárðarbunga)

84) 02-03-2011
64,764, -17,266, 3,3 (1.1 km deep 3,3 km SW of Kistufell)
Not that far from the last one

85) 02-06-2011
64,501, -17,609, 3,4 (1,1 km deep, 9,7 km E of Hamarinn)

86) 02-06-2011
64,689, -17,020, 3,3 (1,1 km deep 13,6 km SE of Kistufell)

87) 02-06-2011
64,753, -17,256, 3,0 (2,7 km deep 3,8 km SW of Kistufell)

Kistufell is not on that map, but is just a little north. And in looking for a map showing the location (shown below) I found the Iceland Volcano and Earthquake Blog which suggests that there are often a lot of earthquakes in the region, and that, by themselves this is not a reason for concern. That has since been updated (I suppose in light of the Telegraph article) to a post yesterday drawing attention to the IMO Press release which says:
Presently, there are no signs of an imminent volcanic eruption in Iceland. The Icelandic Meteorological Office (IMO) did not issue a warning last weekend in connection with increased seismicity beneath the Vatnajökull ice-cap. If signs of an eruption were apparent, IMO would issue a warning immediately.

Location of Kistufell relative to Bardarbunga. Note the frequency of small earthquakes around the site – this in December 2009. (Iceland Volcano and Earthquake Blog)

Well with that concern abated for now, let me just reiterate why I remain a little concerned about Laki and Katla. As I have watched the IMO site over the past 9 months I have noticed that there has not been much activity in the Laki region. That is the region between Katla and Loki. If the two plates are continuing to move, and the quakes along the line show that they are, then there should also be small quakes in this region to allow the plate movement. There has not been that much, and it might indicate a build-up in stress in the region, so that when the point of failure occurs that it might be more violent.

It was the eruption of Laki, along a 15-mile fissure in 1783 that has, among other things, been blamed for the French Revolution. The eruption was so severe and so long that it killed a quarter of the Icelandic population, affected not only the European harvest but also led to a very bitter following winter (the Mississippi was reported to have frozen as far south as New Orleans).

The other concern is down at Eyjafyallajokull, and as was noted at the time, this has in the past been a precursor to the eruption at Katla about 18-months later. Well just in case that is going to happen again this year, I decided to map, by month, the quakes in the region, starting last month.

What I am interested in is to see whether there is a channel set opening from the original eruption that would lead to the Katla caldera. I have only been doing it since January, and had not planned on posting it until I had more data, but if you squint at this map in just the right way, you can see that there might be a connection forming. We will see, as the year moves on.

Earthquakes around Eyjafyallajokull in January 2011. (All below M3) (Source IMO)

But for now, panic over, we can go back to worrying about oil, natural gas, politics and the climate. (I believe it got down to 2 degrees F here last night, and I have a walkway to clear).


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