2025 Volume 29 Issue 2 Pages 77-82
In order to understand and predict the seismogenic processes of large earthquakes that repeatedly occur in the Nankai Trough region, we aim to monitor the status of plate boundary locking by not only monitoring earthquakes and tsunamis but also conducting real-time observations of seafloor crustal deformation. To achieve this, we have been conducting technical developments and implementing them in the Nankai Trough region, including long-term seafloor pressure observation through in-situ calibration of seafloor pressure gauges, seafloor tilt and strain measurements, distributed optical fiber sensing using submarine optical fiber cables, and the development and deployment of long-term borehole observation systems in wide area. Based on these technological developments, several future technological challenges and areas for further development have been identified. These include the integrated real-time analysis of earthquake and seafloor crustal deformation data, high-precision seafloor mapping and leveling over wide areas using autonomous unmanned vehicles, high-precision temperature and strain measurement using optical fiber sensing, and deep seafloor drilling to reach plate boundary and the installation of borehole sensors. Furthermore, long-term maintenance of the submarine cable observation network infrastructure is essential for understanding the transition in the seismic cycle of the large earthquake zone, and thus, updating and enhancing the infrastructure with new technologies is necessary.
