Saturday, March 15, 2014

El Hierro earthquake activity increases again

After almost three months of relative calm on El Hierro island since the strongly-felt 5.1 earthquake on Dec.27th, 2013, in the past two days a new 'swarm' of minor shocks was recorded there. Of the more than 165 events since Thursday most were of magnitude 2 or less and the strongest was a 2.4. They almost all occurred in safe depths of between 15 and 20 kms and none was felt by the population.
The location of the recent quakes is new however as the bulk of the activity now is happening under the eastern half of the island. Previous activity was concentrated under  and around the western parts of El Hierro. A new intrusion of magma is the likely explanation for the renewed activity and it remains to be seen what further effects, if any, it will have on the neighbouring island. Almost exactly on year ago there was a sudden swarm of quakes which then culminated in a magnitude 4,9 shock.
The total number of recorded El Hierro earthquakes since the beginning of the current cycles of activity in July 2011 now stands at a whopping 21.500 and counting.
Locations and depths of recent El Hierro earthquakes

UPDATE Sunday March 16th, 2014, 10:30am:
The renewed activity continues unabated and by now there've been 270 minor earthquakes in the past 3 days. There is no change in the depth and the strength of the shocks remains around and below magnitude 2. Most of the quakes are still in the eastern central El Hierro region.
UPDATE Monday March 17th, 2014, 6:30pm:
The activity has decreased considerably, but deformation of the island has increased again. No other changes.
UPDATE Tuesday March 18th 2014, 9pm:
...and once again activity has almost ceased with just four very minor shocks today. The general see-saw of volcanic activity on El Hierro just experienced another upturn, and each time it seems to happen in a different way. I am ending this post and will report any future developments in a new post.

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