Researchers: Ocean Trench Stress Off Hokkaido Indicates Possible Mega - Quake
Observations made by Japanese researchers indicate that unreleased stress energy at an undersea trench off northern Japan could trigger a massive earthquake and tsunami.
Researchers from Tohoku and Hokkaido universities and the Japan Agency for Marine-Earth Science and Technology have been monitoring the Chishima Trench zone off the coast of Nemuro City in eastern Hokkaido.
They installed three ocean-floor base stations in 2019 on the sides of the trench where an ocean plate sinks beneath a continental plate.
They observed changes on the seafloor by sending sonar signals from a surface vessel to the stations and measuring the echo time.
They found that over the course of one year, all three stations moved seven centimeters toward the continental side. This led them to conclude that the two plates may have partially stuck together at a shallow part of their boundary.
They warn that the zone requires further monitoring, as the release of built-up stress could trigger a mega-quake.
They say they will continue to monitor the zone and carry out analyses.
Tohoku University Associate Professor Tomita Fumiaki, says the situation calls for caution. He noted that plates adhering in a shallow area of the boundary could cause a major earthquake and tsunami similar to those in March of 2011.