On-board Diary: Channel of Majorca. Pockmarks, holes in the seabed.
Author: Silvia García
Date: August 7, 2010
After spending the night, we anchored at Cala Tarida, to the west of Ibiza. We set out early again toward the pockmark area between Ausias March and Ses Olives where we had already been on the 4th. Now our goal is to find, if possible, these curious geological formations on a seabed deeper than 500 m.
These are “holes” that form on muddy seabeds by events of escaping gas. They usually appear as lines of very subsidences just a few meters deep. In this area, to the west of the Pitiusas, there is a field of pockmarks, that we have georeferenced, as the area had been sampled beforehand during an IEO (Instituto Español de Oceanografía) oceanographic campaign.
Our intention is to be able to film these formations, and, if we are lucky, detect emissions of gas that is still active. We did a long submersion in the area, and we found rich fauna that is typical of those deep muddy seabeds. There was a variety of crustaceans, fish and some deepwater gorgonians. But unfortunately, we did not reach our goal, because it is not that easy to direct all that equipment (ship+ROV) toward such a specific point like a hole that is just a few meters in diameter on a seabed that is over 500 m deep.
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