Canary Island Landslides and Potential Megatsunami
The Canary Islands are a group of seven volcanic islands that lie 100 kilometers off the coast of Africa. These islands grew over a hotspot as in the Hawaiian islands and all but one has active volcanoes. The coastlines of the Canaries are characterized by massive, steep cliffs and there has long been speculation that these features formed by dramatic collapse. What makes this possibility super significant is the fact that this process could trigger massive tsunamis that could hit the coasts of Europe, the eastern seaboard of the US, and Antarctica. In fact, speculation is that giant blocks of limestone that weigh hundreds of tons meters above sea level in the Bahamas were delivered there by a megatsunami and the Canary Island landslides are a possible culprit. And more locally, tsunami deposits found in the Canary island suggest waves in the past over 150 meters high!
Cumbre Vieja is the main volcano on the island of La Palma and has erupted recently causing large cracks to grow involving the significant motion of the western volcano flank. This has caused speculation that this flank could collapse. The flank has a volume of 1.5 trillion metric tons and models suggest that if it were to collapse it would generate a tsunami 1000 m high that would be 50 m when it arrived in Europe and along the eastern coast of the US. Because this scenario would be devastating to cities including New York, Boston, and Miami as well as coastal real estate in New Jersey, North and South Carolina, and Florida, it has been rigorously investigated by scientists.
Video: Megatsunami Scenario - La Palma Landslide (4:48)
The hypothesis that Canary Island collapse generates megatsunami is not universally accepted. This skepticism arises from the fact that island collapse may not have been catastrophic, instead, occurring slowly in numerous discrete small events rather than a single giant collapse. Such a slow collapse would not generate a large tsunami. So what about the large Bahamian blocks? An alternative possibility is they were delivered there by a hurricane during a time 125,000 years ago when sea level was higher than it is today.
In summary, it does not appear that a devastating megatsunami generated in the Canary islands is imminent. There is potential for collapse of the volcanic flanks on the islands but these events will likely be less dramatic than once feared and with waves only devastating on a local scale.