Thursday, December 22, 2011

El Hierro Resumes Activity With Strong Vent Action



Just when we think that the El Hierro is winding down, it renews its eruptive activity. So far this is what has occurred on the island during the eruption.

The eruption was preceded by over 8,000 small and deep earthquakes, with harmonic tremor being recorded throughout. The volcano then opens a vent on the sea floor, about a mile SSW of La Restinga, at depth. The underwater volcano erupts producing a large "stain" on the surface, and residents reported "jacuzzis" out in the ocean water that bubbled, and churned, sometimes producing steaming floating pumice type rocks. This activity continued for over a month, and it was thought that the volcano might breach the surface to form a new island. This has not occurred yet, although for a brief moment, the volcano appeared to have at least erupted some incandescent material as per an earlier post.

Activity has indeed decreased and on some days, there is no activity to be seen on the oceans surface. The past few days showed a light 'stain' on the ocean surface, but no jacuzzis. The jacuzzis stopped about a week ago, and it had been assumed that the main vent had closed. About two days ago, two new stains appeared, which has been interpreted to be flank eruptions of the underwater volcano, possibly due to the pressure at the underwater summit being so great, that lava oozed out of its sides. The pressure at the summit seems to have been lifted, with today showing the stain and a small 'jacuzzi' over the previous summit location. This could indicate that the pressure and amount of magma in the chamber is still quite sufficient to continue the eruption, for who knows how long.

Also, earthquake activity has slowly resumed, with more powerful jolts. A 2.8 quake hit the island today, near the El Golfo bay, further fueling speculation that yet another vent may be active at great depth in the landslide area. This of course is not, and at the moment, cannot be confirmed, as eruptions at that depth would likely leave no surface evidence.

So it seems that despite its short break, El Hierro is at this time, continuing to erupt. Of course, I will keep my eye on this evolving situation and update as necessary.

Enjoy the time lapse video from earthquake-report.com of the renewed activity.

                                  

During the end of the video, there is an interesting looking white object that appears to come out of the water, move slowly toward the vent, and then submerge. This is an illusion as it is merely a solar artifact that is reflecting off the lens... caught me by surprise though!

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