Scientists Study Impacts of Tohoku Earthquake on Deep-Sea Floor

Dr. Kazumasa Oguri, Senior Research Scientist for Analyses of Changes in East Japan Marine Ecosystems and his colleagues at JAMSTEC carried out long-term monitoring of the seafloor environment off Otsuchi Bay to investigate environmental changes of the deep-sea floor after the 2011 off the Pacific coast of Tohoku Earthquake.

Two self-powered deep-sea stations were deployed on an upper continental slope site (around 300m water depth) and on bathyal (998m) site. The respective monitoring periods were from March 13, 2013 to September 12, 2013 (upper continental slope) and from August 12, 2012 to October 12, 2013 (bathyal).

These long-term monitoring provided high-resolution environmental data in one hour interval and their time-series data illustrated seasonal changes in bottom water characteristics, which had not been available before.

In particular, seafloor photographs and videos clearly recorded the disturbance and their subsequent recovery of benthic habitats after the largest aftershock during the monitoring period, which hit near the Japan Trench on December 7, 2012, measuring at magnitude 7.3.

These data will contribute to long-term forecast models of oceanic environmental variability and also for planning of fishery activities. The research group will continue these observations to introduce data telemetry system using with an underwater winch technology for semi-real time monitoring.

This project was carried out as a part of Tohoku Ecosystem-Associated Marine Sciences funded by Ministry of Education, Culture, Sports, Science and Technology.