Found this excellent 2017 article series from the Landslide Blog through some public outreach GVP did yesterday on Twitter.
Understanding the La Palma mega-landslide hypothesis: part 1
As I noted in an earlier post, I spent a part of last week on the island of La Palma in the Canary Islands. Whilst my visit was to mark the opening of the GOTO telescope in my Vice-President role, I also took two days to explore the supposed mega-landslide that, it has been suggested, could generate a huge and very damaging tsunami. I have noted before that I do not subscribe to this hypothesis, but welcomed the opportunity to explore the site. In this and at least one subsequent post I will try to explain the mega-landslide hypothesis, and will also seek to outline why I do not think it stands up to scrutiny.
The La Palma volcanoes
The Google Earth image of La Palma below shows the main features of the island. I have provided an annotated version on the left alongside an unannotated version for clarity…
Read the whole thing.
Understanding the La Palma mega-landslide hypothesis: part 2
Earlier this week I explored the main structural features of La Palma that have led some to propose that there is the potential for a mega-landslide there. This proposed volcanic flank collapse would be immense – the proposed volume is up to about 500 cubic kilometres. The idea that gained some popular traction is that this landslide could generate a tsunami that would devastate a large part of the coastline on both sides of the Atlantic.
Of course La Palma has undergone a previous flank collapse event, and there have been similar collapses elsewhere in the Canary Islands. Interestingly, none of these appear to have generated widespread tsunami deposits around the Atlantic basin. The key to the idea such an event developing again is the events of the major eruption in 1949. During this event, a fault structure was observed to develop along a part of the Cumbre Vieja ridge. This has been interpreted as indicating movement of the flank of the volcano towards the west, and thus the development of a potential flank collapse landslide on the southern part of La Palma. I spent a day up on Cumbre Vieja, with the main aim of taking a look at this fault scarp…
Read the whole thing.
Featured image: Martin Lovekoski, CC BY- NC 2.0.