That's a hypothetical "hazard" of a megatsunami and on top of that, seems reaaaally unlikely to happen within the lifetime of any of us:

> Giant landslides are rare events.[117] Humanity has never witnessed enormous collapses on La Palma[59] and there is evidence that the western flank of La Palma is currently stable[65] and a collapse in the near future is unlikely.[133] A worst-case scenario giant landslide like the one modelled by Ward and Day 2001 is a very low probability event, probably much less common than once per 100,000 years[123]

But, never say never, apparently we're ruining the planet faster than anyone of us thought possible just 50 years ago, so who knows what could happen.