prehistoric, bone, totem, incised, BearGod

North Atlantic Logbook

Looking at "Big Time"... from 20,000 BC onward

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Recent Eyjafjallajökull Activity Evaluated
prehistoric, bone, totem, incised, BearGod
michaelbix
Icelandic Meteorological has released a report - http://en.vedur.is/about-imo/news/2010/nr/1859 in which the seismicity of Eyjafjallajökull just prior and following its first eruption has been traced as a 3-D set of plots.

I've reset their diagram to alternate positions so that its parts can be easily compared along two axes.



Please note that this is for a specific time frame 13-24 March, not for the entire pre-eruptive sequence. One can observe in this summary, three consecutive "pushes" upward on the 17, 18 and 19th - followed by more than 24 hours of near silence.

Then came the first eruption late on the 20th of March, in a direction previously weakened but not "used" in the prior few days. I find this exploitation of weaknesses, just as happened before the opening of the second larger fissure (preceded also by a long quiet) to be both peculiarly interesting, as well as a bit troublesome. It suggests that when the magma DOES come through at any opportunistic weak point, it has already "tested" it... opened and smoothed pathways to it with some prior set of exploratory surges; and then "keeps it in reserve" until such time as the magma pressure from below requires more outlet than the pre-existing vents provide.

And then... it comes through that "reserved" weak point. There is a set of further lines of previous "exploration" even further to the west that have yet to be opened, as well as some on the south face. So it will be interesting to see what Eyjaf continues to do, especially if magma pressure from below increases significantly.

Again, the link to the Veðurstofa Íslands explanation of earthquake/magma event procession - http://en.vedur.is/about-imo/news/2010/nr/1859

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