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.
Possibility of Megaquake Occurring Near Chishima Trench Within 30 Years
A megaquake is believed to have occurred near the Chishima Trench over 400 years ago. The government’s earthquake panel believes that the built-up strain from that 17th century quake could be equivalent to the energy released by a megaquake. According to the panel, the possibility of an earthquake with a magnitude of at least 8.8 occurring near the Chishima Trench within the next 30 years is somewhere between 7% and 40%. The government projects up to 100,000 deaths if a 9.3 megaquake hits the Chishima Trench.
With the 14th anniversary of the 2011 Tohoku earthquake and tsunami approaching, Tomita Fumiaki, an assistant professor at Tohoku University International Research Institute of Disaster Science, is urging people to be vigilant as another huge quake could occur at any time. “We need to think again about what we can do to prepare for another megaquake,” he told NHK.
