Monday, February 6, 2012

Powerful Tremor This Morning At El Hierro, Then Significant Decline


Early morning at El Hierro displayed lots of activity at the volcano, as seismic tremor more than tripled the average of the past few days. After this long (3-4 hour) period of heightened activity, the tremor has ground to a near halt for the last 12+ hours. This has become quite the pattern at El Hierro, where there will be periods of heightened explosiveness underwater, followed by a day or so of quiescence, with violent resumption of activity for a few hours after the pause. I would assume that given this pattern, there will most likely be more activity tomorrow morning.

The current tremor graph below:


                               
El Hierro has been a confusing volcano to watch as it has stopped and started its eruptive phase several times. It is unclear at this point whether or not this will be the main event at the volcano, or if there is more in store for this island. There have been rumors of thermal anomalies on the actual island as of late (as per a video on Earthquake-report.com) that are UNCONFIRMED, and probably bogus, as well as rumors of a 2nd vent in the El Golfo region of the island (the North shore). Due to depths off the North shore, this has never been confirmed.

The magma chamber under El Hierro has seismic implications of being quite large, not by any means a monogenetic cinder cone eruption. It is likely that this eruption, and activity at El Hierro as a whole, may continue for some time.

After the activity this morning, El Hierro has been pretty quiet. Late afternoon observations showed a weak stain, and high surf, which has washed a lot of the discolored water away from the vent area. When the ocean calms down, activity will likely be more apparent.



*****UPDATE*****

As I suspected, given the pattern of eruption so far for El Hierro, tremor has indeed again picked up some 24 hours after the last spurt of activity started. The eruption is currently producing elevated tremor, and the occasional flaming lava balloon can be seen on the water surface. Below is today's tremor reading, where you can see the nearly perfect 24 hour relation that has been the case for the last week or so.




The volcano will probably have 2-4 hours of high tremor, collapse the vent again, and re-pressurize about 20-25 hours later resulting in the resumption of tremor... let's see if this pattern holds!

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