A collapse on the western slope of the Cumbre Vieja volcano on the island of La Palma could trigger a megatsunami across the Atlantic Ocean and affect the US East Coast. According to a Science Focus publication, scientists can model the consequences, but not determine when such a scenario would occur.
The attention to Cumbre Vieja is related to changes on its western slope. During an eruption in 1949, part of it broke off, and in the 1990s, a research team found that a large mass of rock was slowly moving towards the ocean.
Different models for wave heights
In the most pessimistic model, the collapse could initially form a dome of water nearly a kilometer high. Then the waves around La Palma and neighboring islands could reach hundreds of meters. About nine hours later, waves about 20 meters high could reach Florida.
Other calculations indicate that the waves along the American coast could be about half as low. However, this does not mean that the risk is limited. Waves of similar size could cause widespread destruction in coastal areas.
The differences come from different assumptions about the volume of rock that would collapse and the way the waves propagate across the Atlantic Ocean. Science Focus emphasizes that these are scenarios, not predictions of an impending disaster.
Faster waves and shorter intervals
Volcanic tsunamis can move faster than waves caused by underwater earthquakes. The intervals between waves can also be shorter, leaving less time for reaction and evacuation.
Historical examples show the consequences. The eruption of Krakatoa in 1883 is associated with the deaths of at least 30,000 people. In 2018, the collapse of the Anak Krakatau volcano triggered a tsunami that killed more than 400 people.
Observation can provide time for evacuation
Satellite and ground-based observations allow us to monitor the instability of volcanic slopes and signs of an impending eruption. In many cases, this could provide weeks of warning and allow time for organized evacuation.
The problem is that hundreds of active volcanoes on islands and coasts are still not well monitored. “We can't say where the next volcanic tsunami will occur or how big it will be, but it will happen”, summarizes author Ezzie Pearson.
Sources: news.bg, sciencefocus.com