DONET (Dense Ocean floor Network for Earthquakes and Tsunamis; https://www.jamstec.go.jp/donet/e/index.html) is a cabled seafloor observatory that monitors the Nankai and Tōnankai seismogenic zones, offshore southwestern Japan, in real time. In 1944, two segments of the Nankai megathrust ruptured in the magnitude 8.1 Tōnankai earthquake; two years later, two other segments of the megathrust ruptured in the magnitude > 8 Nankai earthquake. Earthquakes are thought to recur in this region every 100–200 years, based on historical information. Therefore, it is important to monitor the Nankai Trough megathrust earthquake seismogenic zone over long time periods to provide early warnings of impending significant earthquakes and to improve the accuracy of earthquake recurrence cycle simulations.

Kaneda, Y. 2014. DONET: A real-time monitoring system for megathrust earthquakes and tsunamis around southwestern Japan. Oceanography 27(2):103, https://doi.org/10.5670/oceanog.2014.45.