Monday, November 14, 2011

The Icelandic volcano at Katla is becoming yet more active

I realize that any claims I have as a prophet have faded as the ash that lies on the Myrdalsjokull glacier from the Eyjafjallajokull eruption last year, failed to be blown away under the summer sun. The underlying volcano, that is Katla, while focusing the earthquake activity in the region has done little more than have a relatively small jokulhlaup (or glacial flood) or two. But I can’t help stirring that old pot at least one more time. Because the earthquake activity at the site remains focused in the caldera, and there has been a recent increase in the frequency with which magnitude 3+ quakes have occurred at the site. I was checking on the one that happened last week, and noticed that there are two new ones since last I looked.

Earthquakes in the last 24 hours around the Katla volcano in Iceland (Icelandic Met Office)

UPDATE: The Icelandic Met Office has another page, which shows the quake map in a different mode, and also gives the frequency over the past day. It currently shows an interesting pattern for the quakes of the last 24 hours.

Earthquakes around Katla in the last 24 hours (Icelandic Met Office ) The line follows that of the perimeter of the caldera (the black hatched line).

Note the site also shows the corrected size of the earthquakes, while the earlier site gives an automated assessment. and, as an update, there are consequent tremors that are falling along the same boundary.

The larger earthquakes are also increasing in size, these two being a 3.8 and then a 3.3, occurring about 3 km apart, which with the intervening activity (the red dots) which included a 2.4 suggests that there just might be a fissure opening. (The now corrected values are given in the lower figure).

Three days ago Jón Frímann noticed signs from his geophones indicating that a new dike had intruded into the caldera. The current activity is a little north of that event, it is also very shallow, with the first and larger quake being at 2.5 km depth while the subsequent ones are down around 1.1 km.

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