Methane hydrate distribution along the Nankai Trough as inferred from BSR occurrence

摘要

BSR (Bottom Simulating Reflector), is the key to investigate the distribution of methane hydrate. The previous research was insufficient to identify the BSR's distribution using the seismic sections, although there are a lot of seismic data in which JNOC (Japan National Oil Corporation) had been conducting the seismic surveys from 1970's to 1996 offshore Japan. The research program of methane hydrate was planned by METI (Ministry of Economy, Trade and Industry) from 1995 to 1999 FY and the seismic survey targeted for methane hydrate was carried out at 1996 FY. The location of the drilling site was determined using the above data, and the core sample of the methane hydrate was recovered from the well at 1999 FY. In 2000, the review of BSR distribution was carried out using seismic data with JNOC and a private company, and it is confirmed that BSR is widely distributed around the offshore Japan, especially at the landward continental shelves from the axis of Nankai Trough. During this work, we draw the distribution map for BSR and classified into 5 groups with considering geological features.