As pointed out by Diana Barnes our collective VC gut feelings tell us that Hekla is up to something.
Image courtesy of IMO
Strain counts reacting to the 7.2 magnitude earthquake today at 03:05:53 GMT at the Kuril Islands.
For those people, including me, who always wondered, but never dared to ask, what the heck this ominous strain count means, this might be a good read: http://ebooks.gfz-potsdam.de/pubman/item/escidoc:43310/component/escidoc:56114/IS_5.1_rev1.pdf
In short, volumetric strainmeters or dilatometers measure the change of a certain volume embedded deep in a borehole to protect it from wind, in a certain time and are therefore a good measure of ground deformation. This is in contrast to seismometers, which respond to ground acceleration.
Strainmeters are susceptible to movement caused by all kinds of sources transferring energy to the ground, e.g. waves pounding on the nearby shore, pneumatic hammers, wind-blown trees, atmospheric pressure changes, temperature changes deforming elastic rocks (think of a crackling radiator) and groundwater changes. Finally the instruments can have some “drift”. Thus, the final signal should be interpreted by a trained professional.
In this regard it should be noted that there is a strong gale warning in effect for the central Icelandic highlands today.
Image courtesy of IMO
Again, there has been a small earthquake (magnitude 0.8) today West-South-West of Hekla at 11.8 km depth. Islander was speculating “My theory is that these Micro-quakes be precursior to Hekla eruption (altough they are in both SIFZ and Hekla Volcano Active Area, within the “flank crack system”), but it can be days or weeks left. Another take could be that next eruption fissure be from 12km SW of Hekla to 5 km NE of Hekla – 17 km long fissure ?” Well, from my internet-touristic point-of view a small Hekla paroxysmal event would totally suffice.
Earthquakes around Hekla from 1995 in white, Feb 2nd to March 3rd 2000 in green, and from March/April 2013 in cold to warm. Image by chryphia
View from South towards North. Earthquakes around Hekla from 1995 in white, Feb 2nd to March 3rd 2000 in green, and from March/April 2013 in cold to warm. Data from hraun.vedur.is, http://www.seismo.helsinki.fi/mohomap/ and Geodas-design-a-grid. Image by chryphia
Historically speaking the current swarm seems within the boundaries of where previous earthquakes occurred.
Post updated with this 3D video:
Image by chryphia
As of the time I was unexpectingly writing this post in a bit of a hurry, there was no volcano riddle available, but instead here is a photo of a stone I found on the southern coast of the Baltic sea this week. Maybe it is basalt. Maybe you should give it a name ;-).
Cheers! chryphia
VolcanoCafé 
Ot; got a call from the Airtanker outfit I am going to be working for this summer.
1. May 15th-start of ground school and training.
2.Then to Anchorage Ak , for simulator work at Northstar and the 4-engine Douglas sims.
3. then the contrct in Meford,Oregon for the fire season..
“When I come to the edge of all the light I know, and am about to step off into the darkness of the unknown. Faith is knowing one of two things will happen: either there will be something solid to stand on or I will be taught how to fly.”
Barbara J. Winter
Let’s go flying . . .
Stay safe, congrats, I am sure the local people will be thankful.
Sounds exciting and dangerous, but also worthwhile. The perfect kind of job! 🙂
New post is up https://volcanocafe.wordpress.com/2013/04/21/sunday-summary-and-a-riddle/