Ancient landslide in the Red Sea can cause a tsunami 21m . high

Researchers predict a giant tsunami that could devastate the coasts of Egypt and Saudi Arabia based on landslide tracks 500 years ago in the Red Sea.

In the discovery, published February 3 in the journal Geophysical Research Letters, researcher Sam Purkis observed a fissure 3m wide and 8m high at a depth of 900m in the Strait of Tiran. "I immediately realized we were seeing traces of geological activity that broke the seafloor," recalls Purkis, a marine geoscientist at the University of Miami.

Submarine explores rifts under the sea.

Further research revealed that this was the result of an undersea landslide, likely creating a 10m-high tsunami that hit the coast of Egypt about 500 years ago. Today, that piece of land still wobbles at the edge. If the landslide continues, computer modeling suggests the event could lead to a tsunami twice as large as the previous one. Even when earthquakes occur in the area, tsunamis of this size rarely form. "It only takes a small tremor in the wrong place and an entire outcrop can collapse, triggering a tsunami much larger than it was 500 years ago," explains Purkis.

The Red Sea is a spreading zone, which means that the area is expanding as two adjacent tectonic plates gradually shift. Slopes along many locations along the Red Sea coast can be especially dangerous in straits or narrow passages, where waves can cause rapid landslides with little awareness.

For example, in the Strait of Tiran, the team said that a 20m high tsunami could cause severe damage to coastal urban areas in Egypt and Saudi Arabia. According to the model, an Egyptian resort town lies directly on the path of the tsunami. A risk assessment is essential, given that even with a slip of about 30 meters, a landslide half a millennium ago created waves so strong that they hit the shore within minutes.

If in the future, the soil slips another 50m, the model shows that the first place to be affected is the city of Sharm El Sheikh in Egypt. Within 1 minute and 30 seconds, waves hitting the shore here can be up to 21 m high. If the ground slips another 100m, the wave entering Sharm will be 35m high. To the north, at Mouse Bay, waves can be as high as 45m, hitting the coast in less than 3 minutes. After a few minutes, the coast of Saudi Arabia across the strait was also affected, although the wave was smaller. In the worst-case scenario, the researchers think the wave reaching Saudi Arabia would reach a height of 15m.

Predicting when a tsunami will strike saves lives and protects infrastructure. The team believes that underwater landslides in the Red Sea should be monitored like earthquakes.