Review of Methane Seepages in the Okinawa Trough: Progress and Outlook

Table 1

Acoustic observations associated with gas seeps in the Okinawa Trough.

Reference	R/V	Method	Observations
Luan and Qin[10]	Kexue Yihao	Echo-sounder; HLAC 15 and 150 kHz; Single-channel seismic, air gun	Gas column, acoustic turbidity, mud diapir in MOT
Xu et al. [11]	Kexue Yihao	2-D multichannel seismic data	Mud diapir, migration of free gases along normal faults, BSR and AWO, high velocity in SOT
Li et al. [13]	N.D.	2-D seismic data	Shelf-margin deltas, submarine channels and canyons, slope and floor fans, mud volcanoes, gas leakage, BSR
Tsai et al. [14]	Ocean researcher I&II	Single-beam echo-sounder; EK60 38 kHz	Gas plume, hydrothermal circulation in SOT
Li et al. [15]	Dongfanghong Erhao; Haida Hao	2-D multichannel seismic data, sparker; Multibeam echo-sounder; EM122 12 kHz	Gas plume, seafloor doming, backscattering features, seeps in transtensile regime in MOT
Li et al. [16]	Dongfanghong Erhao; Haida Hao	2-D multichannel seismic data, sparker; Multibeam echo-sounder; EM122 12 kHz	Gas plume, seafloor doming, backscattering features, gas chimney, spatial relationship between faults and seeps in MOT

NOT: northern Okinawa Trough; MOT: middle Okinawa Trough; SOT: southern Okinawa Trough; N.D.: not documented.