The fear of underestimated 'volcanic tsunami'
The fear of volcanic eruptions is sometimes discussed in Japan as well, but the concrete images of this are mostly flint and pyroclastic flow of lava, flowing lava and rolling ash. Among such volcanic disasters, Scientific American explains the threat of the “volcanic tsunami” that accounts for one-fourth of the people who died of eruption damage, although they are not told much.
The Underappreciated Threat of Volcanic Tsunamis-Scientific American Blog Network
The tsunami that occurred in Indonesia in December 2018 was reported to have killed more than 400 people. The tsunami was not caused by earthquakes or currents, but was thought to be caused by landslides that occurred on the sea floor due to volcanic activity.
When a submarine volcano erupts, a large explosion occurs in the water, and the shock wave combines with the sea wave to form a tsunami, and the pyroclastic flow and the like may flow into the sea as the water is expelled by flowing into the sea. There is. The cause of such eruptions and earthquakes is easy to understand as a sign, but 'The volcanic tsunami is caused by the movement of a large amount of water caused by the volcano, not necessarily by the eruption', the sign is Dana Hunter , writer of Scientific American, commented on the horrors of the confusing volcanic tsunami.
Areas called “Lava benches” can collapse suddenly without signs of an eruption or the like, pushing out the water of the ocean and generating local waves as at the time of the eruption. Landform ' caldera ' on basin formed by volcanic activity may cause sudden collapse in the same way and is said to push out a lot of water
In particular, in a phenomenon in which a weak geological mountain called ' mountain collapse ' is triggered by an earthquake or eruption, the amount of water excluded by the inflow of soil increases, and the side volcano formed by the eruption has a considerable geology Because it is weak and prone to collapse, a volcanic tsunami will occur without a small explosion.
The number of times the volcanic tsunami has occurred is less than 100 times in both the 19th and 20th centuries, and it is a rare phenomenon when it is thought that volcanic eruptions occur 60 to 80 times a year, and it is only a small fraction of volcanic activity. There is none. However, it is said that the number of deaths per time is quite high, causing 20 to 25% of the number of deaths directly related to the volcano since the 1700s.
Hazard maps and evacuations in spite of this large impact and not being limited to a specific location on Earth, but considered to be dangerous to many of the Pacific and Central Atlantic coast areas. Mr. Hunter has warned that the path is too little to consider the volcanic tsunami.
in Science, Posted by log1e_dh