Vertical Cable Seismic surveys for SMS exploration in Izena Cauldron, Okinawa-Trough

In 2014, Japanese Government starts “Next-generation technology for ocean resources exploration” program, one of the issues of “Cross-Ministerial Strategic Innovation Promotion Program (SIP)” to accelerate these research and development of sensing technology, sampling technology, development of the method of environmental impact assessment, and so on. We proposed “Multi-staged and Integrated approach to SMS Exploration” and it has been accepted it. Our “Multi-staged and integrated (MSI) approach” includes the Vertical Cable Seismic (VCS) survey technique and EM survey technique as well as the other geophysical exploration tools. VCS is a reflection seismic method that uses hydrophone arrays vertically moored from the seafloor to record acoustic waves generated by various acoustic sources. This method is useful to delineate detailed structures in a spatially-limited area below the seabed in the deep sea where conventional surface seismic is not effective. We have been developing an autonomous VCS system in the other governmental projects since 2009. We have carried out several VCS surveys and completed our VCS system. In SIP program, the high priority target is Seafloor Massive Sulfides (SMS). Izena Cauldron, Okinawa Trough is one of the most promising SMS areas around Japan. There are two high potential areas, the north and south mound. We carried out the first VCS survey around the north mound in 2011 and the second survey around the south mound in 2013 respectively. We summarized these surveys and the result to demonstrate the VCS is suitable tool as MSI approach.