Decipher the mysterious tsunami in the East Sea

Scientists on Oct. 22 warn of potential tsunami areas on the southwest coast of Taiwan after shedding light on a mysterious tsunami that occurred in the area in the 18th century.

Answer the mystery of tsunamis in the East Sea

The tsunami occurred between 1781 and 1782, having the most devastating destruction in history in the South China Sea when it killed more than 40,000 people.

According to scientists from the Earth Observatory of Nanyang Technological University (EOS - Singapore), the cause of tsunamis is due to landslides below the ocean surface. The landslide area is located on the upper part of the continental slope off the southwestern coast of Taiwan, most likely caused by an earthquake.

Associate Professor Adam Switzer of EOS, the head of the 18th-century tsunami team, warned that a similar tsunami that occurred in the same area would endanger millions of people in cities. Taiwan coastal city like Kaohsiung and Tainan, while also damaging infrastructure in southern Taiwan.

These two cities have a total population of 4.5 million and are home to the Maanshan nuclear power plant located on the coast. The latest prediction raises concerns for activists who support the dismantling of nuclear power plants as the island suffers frequent earthquakes.

Associate Professor Adam Switzer.(Photo: Straits Times).

The EOS study was first published in Geophysical Research Letters (published by the American Geographic Society) earlier this month. Geographically , underwater landslides occur when sediments accumulate on a slope on the ocean floor. If an earthquake occurs, the sediment will collapse into a large space for sea water to enter, causing a tsunami.

Associate Professor Switzer said an earthquake of about 7 on the Richter scale was able to create such a tsunami. In the last century, southwest Taiwan experienced three earthquakes with a magnitude of less than 7 on the Richter scale.

Most recently, in 2006, a 7.1-magnitude earthquake off the southern coast of Taiwan caused an underwater landslide, which may have caused the submarine cable to be damaged and Internet service. intermittent telecommunications in Southeast Asia. This earthquake also caused a tsunami, but only created waves with a maximum height of 40cm.

Scientists say it is difficult to predict the 'underground' tsunami . "It will definitely repeat again, maybe tomorrow or 100 years later," Switzer said.

Currently, Taiwan is taking safety measures for Maanshan factory by building emergency cooling towers and increasing the height of the sea walls surrounding the factory. Last month, Taiwan tested a tsunami alarm system to make the public acquainted.

However, Mr. Switzer said that if a light signal was caught, the Taiwan government must immediately warn people in the southwest to take refuge, because a tsunami takes only 30 minutes to hit the coast. .