Tsunami file: Recent tsunamis
Tsunamis: Historical overview
January 6, 2004
Before the event of December 26, 2004, four comparable or larger tsunamis had struck the planet since 1900:
- In Chile, in 1960, with a magnitude of 9.5
- In Alaska, in 1964, in Prince William Sound (9.2)
- Again in Alaska, in 1957, in the Andreanof Islands (9.1)
- In Kamchatka (9.0) in 1952
Indonesia had never experienced a tsunami, as far as anyone can remember.
In all regions of the globe where subduction occurs, tsunamis are possible. The Japanese are well accustomed to this phenomenon, to the extent that the word "tsunami" comes from their language. The south of France is not exempt from this risk. A tsunami hitting the Camargue plain "could reach the city of Arles" (Bouches-du-Rhône), 25 kilometers from the coast, according to Michel Villeneuve.
In fact, in 1979, a tsunami occurred in the Alpes-Maritimes, between Nice and Antibes. It destroyed a breakwater at an airport construction site and caused eleven deaths.
In 1986, residents of the beach at Beauduc (Bouches-du-Rhône) were surprised by a two-meter wave following an earthquake in the Mediterranean. There were no fatalities.
According to the French National Centre for Scientific Research (CNRS), 5 to 10% of the tsunamis recorded throughout history have occurred in the Mediterranean, with the rest mainly distributed between the Pacific and the Indian Ocean. Furthermore, the greater depth of these oceans favors tsunami propagation.
In total, the CNRS has recorded about twenty deadly tsunamis in the Mediterranean over the past 2,000 years. The deadliest ones occurred in 551 along the Lebanese-Syrian coast, in Egypt in the 14th century, and in 1908 at Messina, Italy. In 365, in Greece—the most seismically active country in Europe, where a fault similar to that of Sumatra exists—a tsunami killed tens of thousands of people as far as Sicily and Egypt. In contrast to the Pacific, where 26 countries have established early warning systems, there is currently no preventive system in place in the Mediterranean.
On August 24, 2004, a small tsunami occurred in Marseille due to underwater seismic shocks. At the CNRS, researchers describe "an underwater landslide of sediments offshore Marseille, on the continental shelf, at the location where the seafloor depth increases from 100 to 200 meters." On that day, the sea receded by about twenty meters along the beach of Pointe-Rouge in the southern districts of the city, according to lifeguards responsible for monitoring Marseille's beaches. This small but sudden retreat of the sea surprised even local residents, who are not accustomed to witnessing such phenomena, normally absent in the Mediterranean.
The French-language TV channel TV5 presented a brief infographic and a short commentary on the danger of a volcanic collapse in the Canary Islands and the resulting extremely large tsunami that could strike the U.S. coast. A reader may provide us with more precise information on this topic. When entire sections of an ice shelf break off, they can generate spectacular waves. In this case, it would involve a massive portion of a volcanic slope, weakened by water infiltration, potentially collapsing into the sea. The volume involved would be vastly greater than that of a mere fragment of ice shelf. In the immediate vicinity, the wave could reach several hundred meters in height, and possibly between ten and twenty meters when it hits the American coast (&&& distance? Geographic location? ).