JAPAN - Unreleased stress energy along the Chishima Trench off Hokkaido has become large enough to potentially trigger a magnitude 9 megaquake. That is the warning from a research team in Japan. In 2019, researchers from the Agency for Marine-Earth Science and Technology and scientists from Tohoku and Hokkaido universities installed GPS observation stations on the seabed to monitor plate movements. They were placed around the point where an ocean plate sinks beneath a continental plate. Stations on the ocean plate moved approximately 8 centimeters per year toward the continental side. A station on the continental plate also moved around 8 centimeters in the same direction. According to the research team, this indicates that the plates are solidly joined together and strain may be accumulating. They believe the strain has accumulated to an extent that could potentially cause a magnitude 9 megaquake.