Up to 85cm Tsunami Hits Mukho Port, Donghae... First Since 1993

A strong earthquake that occurred near the Noto Peninsula in Ishikawa Prefecture, Japan, caused a tsunami with a maximum height of 85 cm along South Korea's East Coast.

According to the Korea Meteorological Administration on the 2nd, a magnitude 7.6 earthquake struck near the Noto Peninsula, Ishikawa Prefecture, at around 4:10 PM the previous day. The tsunami was first observed at Namhangjin Port in Gangneung City, Gangwon Province, at 6:01 PM, 1 hour and 51 minutes later.

[Image source=Yonhap News]

A tsunami is a very long wave generated by an earthquake on the seabed or a volcanic eruption causing the sea surface to oscillate. The propagation speed of a tsunami varies depending on the depth of the sea. The deeper the water, the faster the propagation speed. The East Sea has a depth of about 2 km, so the tsunami propagation speed is approximately 500 km/h. Therefore, when a strong earthquake occurs near the Noto Peninsula as in this case, the tsunami reaches the East Coast about 1 hour and 30 minutes later.

The highest tsunami height recorded along the East Coast this time was 85 cm (observed at Mukho Port, Donghae City, Gangwon Province, at around 8:35 PM). This exceeds the criteria for issuing a tsunami advisory. A tsunami advisory is issued when "an undersea earthquake of magnitude 6.0 or higher occurs, and a tsunami with a height of 0.5 m (50 cm) or more but less than 1.0 m is expected to hit the Korean coastline."

The maximum tsunami heights by observation points (observation times) were: Namhangjin 28 cm (8:08 PM), Sokcho 45 cm (8:38 PM), Imwon, Samcheok City 33 cm (9:00 PM), and Hupo, Uljin County, Gyeongbuk 66 cm (8:42 PM).

Generally, when the tsunami height exceeds 0.5 m, coastal lowlands may be flooded, and evacuation to higher ground is recommended. The Japan Meteorological Agency states that a 20 cm tsunami makes it difficult for adults to walk, at 50 cm adults need to hold onto something to stand, and at 70 cm adults can be swept away. For tsunamis over 1 m, standing becomes very difficult for adults, and the risk of death is high.

Even until the morning of the day, tsunamis under 10 cm continued to approach the East Coast. The Korea Meteorological Administration urged, "Although the tsunami height is slowly decreasing, caution is still needed along the coast for the time being."

Meanwhile, this is the first time in 31 years since July 12, 1993, that a tsunami has reached the domestic coast.

At that time, a magnitude 7.8 earthquake occurred in the northwest sea area of Okushiri Island, Hokkaido, Japan, and a tsunami with a maximum height of 2.76 m hit the East Coast. There were no casualties, but property damage of about 400 million won occurred.

On May 26, 1983, a magnitude 7.7 earthquake occurred in the sea area west of Akita, Honshu, Japan, causing a tsunami over 2 m high to strike the East Coast. At that time, there was one death, two missing persons, and two injured, resulting in casualties.

The last time a tsunami advisory was issued was on March 20, 2005. A magnitude 7.0 earthquake occurred in the northwest sea area of Fukuoka, Japan, and a tsunami advisory was issued for the East Coast, South Coast, and Jeju Island, expecting a 0.5 m high tsunami, but no tsunami actually arrived. The earthquake at that time was strong enough to be felt shaking in most areas nationwide, including Busan.

This content was produced with the assistance of AI translation services.