Development of DONET2 — Off Kii chanel observatory network

DONET is a flexible and expandable submarine cabled seafloor observation infrastructure for mega-thrust earthquake research and disaster prevention. The system which consists of a backbone looped submarine cable system, five science nodes and 20 set of state of art earthquake and tsunami observatories was developed and constructed in the program started from 2006 and fully in operation from 2011 at the hypothesis region of To-Nankai earthquake. Simultaneously with the construction of original DONET, the development and deployment of second DONET system (DONET2) was planned and started in 2010 to subject for the hypothesis region of Nankai earthquake. Since this region spreads out in the wide area about 2 times rather than the region of the To-Nankai earthquake, deployment of a large-scale observation network system is required. Expansion of scale of observatory means the increase of power distribution capacity and the confliction of network topology, it will need to solve the several engineering subject to expand the design of original DONET to large scale system DONET2. This paper describe several indispensable technologies of submarine cabled seafloor observation system DONET (power consumption control, power blanching and time synchronization), then introduce the novel engineering approach for high voltage power distribution control and large scale network topology management for DONET2 off Kii channel observatory network.