Land mysteriously rising from the sea along northeast coast of Japan said to be caused by massive landslide

April 2015 – RAUSU, Hokkaido – The appearance of newly formed land along Shiretoko Peninsula’s southeastern coast is causing a stir. The unexplained mass measures roughly 300 meters to 500 meters long, 30 meters wide and rises 10 to 15 meters above sea level, a town official said April 25, a day after it was discovered. A local woman who was harvesting seaweed along the shoreline on the morning of April 24 noticed the area seemed to be slightly more elevated than the last time she was there. When she finished her task, the area had risen even further, exceeding her height.

“The local residents said they didn’t hear any sounds and there were no tremors (when the land appeared),” said Katsuhiro Tanaka, the president of the Rausu Fisheries Cooperative Association, who viewed the expanded coastline the day it was discovered. Marine organisms such as seaweed and sea urchins are attached to rocks on the land mass, suggesting it rose out of the ocean. Officials from Rausu have sealed off the area so it can be studied. –Asahi

Crumbling coastline: A man looks into a landslide area near the coast in Rausu, Hokkaido, on April 25. Along the coast, the seabed was found to have appeared above the surface of the water on the previous day. (Kotaro Ebara)

A massive landslide? The sudden mysterious rise of a land mass from the sea along the coast here was apparently caused by a local landslide, according to an on-site study conducted by the Kitami Institute of Technology on April 25. Researchers discovered that part of a hill facing the sea had collapsed. A road along the hill that is located about 150 meters from the coastline has tumbled in a section stretching 20 to 30 meters. According to the town government of Rausu on the Shiretoko Peninsula in eastern Hokkaido, the resulting land mass measures about 300 meters long and 40 meters wide.

Its height above the sea surface is estimated to be six to 10 meters. In the on-site study, Shintaro Yamasaki, assistant professor of engineering technology at the Kitami Institute of Technology in Hokkaido, concluded that a landslide occurred on the hill toward the sea. The landslide pushed up the seabed and, as a result, the sea bottom appeared above the surface, he said. As for why the collapse occurred, Yamasaki said, “I think that melted snow penetrated into the ground and made it easy for the ground to subside.” Hiroshi Fukuoka, professor of landslides at Niigata University, added, “The ground has become fragile on some of the coasts that have become cliffs. That is because of exposure to waves.” –Asahi