El Hierro is a 278.5 km2 island, formed approx 1.2 million year ago[REF] after three successive eruptions, the island emerged from the ocean as a triangle of basaltic dykes topped with a volcanic cone more than 2,000 metres high [REF].
There is evidence of at least three major gravitational landslides that have affected El Hierro in the last few hundred thousand years [REF].