[3] With continued activity resulting in the island expanding to have the largest number of volcanoes in the Canaries (over 500 cones, another 300 covered by more recent deposits), together with approximately 70 caves and volcanic galleries, including the Cueva de Don Justo whose collection of channels is over 6 km in length.

There is evidence of at least three major gravitational landslides that have affected El Hierro in the last few hundred thousand years.

[4] The most recent of these was the 'El Golfo' landslide that occurred about 15 thousand years ago, involving collapse of the northern flank of the island.

Turbidite deposits related to this landslide have been recognized in drill cores from the Agadir Basin to the north of the Canary Islands.

[4] Tanganasoga formed near the top of the El Golfo landslide headwall, on the upper part of the north-facing scarp slope.