Quoting: Gizzie 8598858
Hi AT, I think you may want to take a look at this...A new post has just been posted on Volcano Cafe...Interesting to say the least..El Hierro : a tectonic compression/relaxation mechanism?Hypothesis: the earthquake swarms report relaxation of accumulated, compressive tectonic stresses
Read the full posting here:
[link to volcanocafe.wordpress.com
Would of posted snippets but it is way to much information to post on here. Hopefully someone can dig the Juicy bits out though and post them....
Thanks...here's what catches me:
"The crust under the Canaries, part of the African tectonic plate, is moving north eastwards at 24mm annually in response to drag from the upper mantle."
That would explain some of the quakes however, we've seen 24mm of movement in ONE DAY during these swarms!!!!
"This compressive stress accumulation must be almost silent to seismometers: very few earthquakes have been recorded at Hierro over 25 years prior to 2011."
So...Hierro has begun a phase...something that has not occured in the thousands of years it has been there and it is not stopping. I think this one sentence right here verifies that Hierro is on the road to something substancial and frankly...unpredictable.
"It is the sudden relaxation of accumulated compressive stress that causes the earthquakes. The earthquake swarms are proposed to result from relaxation of compressive stress."
I don't agree with this concept. Show me how the progressive stress is reduced in some measurable capacity and then maybe I'll buy it. The plate doesn't just stop compressing...unless it's overall movement is finally over. Which...the rest of the article does not specify.
What I could buy is that the bulk plate and the surface plate might be finding a way to relax from their movement from each other. What's really interesting is to consider that this archipelago's bulk plate seems to be filtering ativity ONLY towards Hierro and the stress relaxation is offset by sudden deep, sometimes very deep, quakes around the Tenerife/Grand Canary island. We also saw one at 79km deep north east of La Palma a few days ago. That to say the least was interesting...that quake would've been BELOW the mantle...in the core!
Their imagery on #8, and without their actual explanation, may explain why the Frontera Bay region has seen most of the landslides. All the pressure is pushing forwards on the island. However, that also means that at some point the underside of the south can buckle and do a barber chair. It can become so unstable at the water line that it breaks and rolls outwards, causing a reverse slide.
THanks for the link and the info. THat was a great read! :)