Sunday, May 15, 2011

Icelandic earthquakes, volcanoes and time - an update

I have been tracking the earthquakes around the Eyjafyallajokull site in Iceland, where last year’s volcanic eruption occurred. There have been times in the past where the adjacent volcano at Myrdalsjokull erupted (generally much more severely) perhaps eighteen months later. And so I thought that by tracking the evolution of the quakes between the two I might see how this might unfold, and whether this would be such a year. I am clearly indebted to the Icelandic Met Office who provides the basic information that I am copying over.

In updating the map today I was struck by how focused the earthquakes in the Eyjafjallajokull-Mydralsjokull region are forming along certain lines and so I thought I would put up the monthly snapshots that I have been building, while I continue to download the maps and data from the USHCN site in preparation for should normally be the Saturday post. (Sorry that I am running late again this weekend). You should note that I color all the quake sites blue except for those that occur on the first day of each month (when I copy a new map).

Here was the January picture:

And then trimming down the picture for the succeeding months of February:

March, in which activity appears to be more scattered:

April, in which activity is less but more aligned:

And now there is the first half of May, where it seems to be getting more focused. The intense zone between the two mounts has more activity, but some are hidden beneath the overlapping circles:

You can see how there is a developing concentration and alignment of the quakes (and implied underlying fracturing) as the months progress. It is just over a year since the original eruption, so it will be interesting to see how this evolves over the next six months. The island continues to have no earthquakes above a level of 3, which is noteworthy, perhaps, in itself.