CARITA, Indonesia/TOKYO -- At least 373 people are dead and 128 missing after a tsunami struck the Sunda Strait between the central Indonesian islands of Java and Sumatra, the nation's Disaster Mitigation Agency announced on Dec. 24.
The tsunami appears to have occurred due to an eruption of the island volcano Anak Krakatau, or "Little Krakatoa," and many of the victims of the "earthquake-less tsunami" were visitors to seaside resort areas.
The tsunami struck at 9:30 p.m. local time on Dec. 22. According to Johan Basir, 30, a guide who was on the beach at the time in Carita on the island of Java, "There was a low rumbling sound, and a white wave roughly 2 meters high appeared. Immediately after I yelled for the tourists to run away from the beach, the tsunami hit."
"We know that after an earthquake, you have to escape to higher ground," he continued, a shocked expression on his face, "But this time, a tsunami just came out of nowhere. We're so used to volcanic eruptions that I didn't feel like anything was out of the ordinary."
The Sunda Strait between Java and Sumatra is a popular tourist destination. Along with the long weekend, many people had come with their families and others from Jakarta to enjoy the beaches, increasing the number of people caught up in the disaster. Among the resorts, the Indonesia Disaster Mitigation Agency believe that the greatest number of victims were those visiting Carita's large resort facility "Mutiara Carita."
On the grounds of the resort, the scattered cottages where victims were found were located roughly 20 meters from the coast and at an altitude of about 1 meter above sea level. Security guard Ncuk Supriatna, 40, ran to the cottages on the western side of the resort by the ocean once the waters from the tsunami had receded. "The visitors in the cottages were in a state of panic, and screaming and crying," he said. "Some people (were in such a state of shock that they) didn't even realize they were injured and bleeding."
It appears that the tsunami struck just as the resort guests had finished their dinner and were relaxing in their cottages. When Supriatna, who had taken the injured to the hospital, returned to the cottages the next morning, emergency personnel had already collected a large number of bodies. "There were some 70 bodies, and I think all of them were resort guests. Even at high tide, the cottages have never been hit by water before," he said.
The impact of the powerful tsunami caused cottage walls to fall, and washed away the furniture inside as well as the cars belonging to the guests staying there. The area is covered in scattered debris, and reopening the resort looks to be far away.
There is a possibility that the impact of the tsunami was enhanced by full and high tides, and as the volcanic activity of Anak Krakatau continues, Indonesian authorities are calling for people not to approach the shoreline.
--- Eruption destroys volcano, fallen debris triggers tsunami: experts
The cause of the tsunami is suspected to be from a landslide that occurred on the volcanic island due to the eruption. In Japan as well, there are past examples of large-scale landslides from mountains into the ocean causing tsunamis, and experts warn that people must be more cautious.
According to volcanologist Setsuya Nakada, professor emeritus at the University of Tokyo, several eruptions have occurred on Anak Krakatau over the last few months, and the volcano grew while covering the seafloor with lava. These newly expanded locations were unsteady, and appear to have crumbled into the ocean from the force of the eruption. From satellite photos, Nakada says that a large portion of the southwest side of Anak Krakatau is now missing.
In a major eruption in 1883, the island on which the volcano was located was almost completely destroyed, and a tsunami at a maximum height of 40 meters occurred. An estimated 36,000 people died, and the volcano came to be known as one that causes tsunami due to landslides.
In Japan in 1792, an eruption destroyed Mount Mayu in Shimabara, Nagasaki Prefecture, on the southern island of Kyushu, triggering a large tsunami that hit Amakusa, Kumamoto Prefecture, which faced the volcano on the opposite coast. In 1741 as well, Oshima Island, part of the Hokkaido town of Matsumae in northern Japan, collapsed due to a volcanic eruption, and roughly 1,500 people were killed in a large tsunami that struck the coastline facing the island.
Nakada is calling for people to be aware of the possibility of a tsunami stemming from the island of Nishinoshima, part of the Ogasawara Islands roughly 1,000 kilometers south of the Tokyo Metropolitan area. The area has been volcanically active since 2013.
"It is common that landslides occur when volcanic islands growing from repeated eruptions collapse," he said. "Coastal areas should consider tsunami countermeasures."
(Japanese original by Aya Takeuchi, Jakarta Bureau, and Tomohiro Ikeda, Science & Environment News Department)