GeoLurking says:

March 28, 2013 at 16:18


There are three major scarps. El Golfo, El Julan, Las Playas. The San Andreas segment is believed to be a failed slide. The El Golfo slide destroyed the volcano’s innards, and according to Caracedo (I think) was the third destroying of the volcano. Tinor had a colapse episode on the west, and eventually the Golfo volcano was born as the center of activity moved there. I think El Golfo had two cone building periods, both of which collapsed. The center was off shore of where Frontera is now.

In the early quakes of the modern El Hierro activity, there was a circular “Dead Zone” that was about one km across under and a bit north of the Tangarasoga cone. I don’t think it was a “Dead zone” like Laki, where the crust is too ductile to quake (my evaluation of Laki), but a region of tough hard to fracture material… probably left over hardened magma in the old feeder pipe. That was my read on it at the time.

Other papers have indicated that the basement feed system of the island remains intact, and that there are at least two ancient feed systems down there. One of them has reversed magnetic polarity since it formed during the last Chron. It’s the one on the eastern side up under the ancient Tinor edifice. All other feed systems happened during this Chron.
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