Wide-area Vertical Cable Seismic Survey: Repeated deployment using ROV in Iheya North Knoll, Okinawa-Trough

摘要

Vertical cable seismic (VCS) system has been developed to provide higher resolution structure under the seafloor than conventional surface seismic reflection survey. We have applied the VCS to delineate the Seafloor Massive Sulfides (SMS) which has complex structure since 2009. According to past surveys around SMS area, we have already demonstrated that the VCS is useful to detect the subseafloor layer of SMS. High resolution profile of the subseafloor structure helps us to detect the SMS and evaluate its volume. VCS survey gives high resolution results but it covers a small survey area with a limited number of vertical cables. To expand the survey area, we operated ROV for re-deployments of the VCS in a short survey period. Additionally, the position accuracy of each VCS could be improved because the ocean current during VCS deployment from the sea surface was not affected. The acquired VCS data was processed with standard Vertical Seismic Profile (VSP) data processing flow. The result of interpretative subseafloor profile indicate that a combination of the VCS and ROV cloud achieve wide area and high resolution seismic survey.