Futagoyama |
active, confirmed |
back-arc spreading center |
Okinawa Trough |
24.8674 |
123.3081 |
1270 |
2016 ROV Kaiko dive 717 |
Higa |
active, confirmed |
back-arc spreading center |
Okinawa Trough |
26.5550 |
126.2233 |
1485 |
2015 ROV Kaiko |
Higashi-Ensei |
active, confirmed |
back-arc spreading center |
Okinawa Trough |
28.4393 |
128.1724 |
1220 |
2016 ROV Kaiko dives 723 and 724 |
Irabu Knoll |
active, confirmed |
back-arc spreading center |
Okinawa Trough |
25.2300 |
124.8800 |
1850 |
2000 submersible Shinkai 6500; 1986 seafloor photos did not confirm activity |
Izena Cauldron |
active, confirmed |
back-arc spreading center |
Okinawa Trough |
27.2667 |
127.0833 |
1610 |
1988 submersible Shinkai 2000 |
Kueishan Island |
active, confirmed |
back-arc spreading center |
Okinawa Trough |
24.8333 |
121.9500 |
30 |
1999, likely by SCUBA |
Kueishan Island, offshore |
active, confirmed |
back-arc spreading center |
Okinawa Trough |
24.8333 |
122.0000 |
1200 |
2008 or earlier |
Minami-Ensei Knoll |
active, confirmed |
back-arc spreading center |
Okinawa Trough |
28.3917 |
127.6417 |
740 |
1988 deep tow TV surveys followed by submersible Shinkai 2000; 1986 dredged Calyptogena shells |
Natsushima 84-1 Knoll |
active, confirmed |
back-arc spreading center |
Okinawa Trough |
27.5750 |
127.1417 |
1600 |
1986 submersible Shinkai 2000 |
North Knoll, Iheya Ridge |
active, confirmed |
back-arc spreading center |
Okinawa Trough |
27.7908 |
126.8966 |
1100 |
1995 deep tow survey |
Okinawa Trough, Site ES1 |
active, inferred |
back-arc spreading center |
Okinawa Trough |
30.3303 |
129.0827 |
521 |
1992 dredge only |
Okinawa Trough, Site ES2 |
active, inferred |
back-arc spreading center |
Okinawa Trough |
28.8137 |
128.1028 |
779 |
1992 dredge only |
Sakai |
active, confirmed |
back-arc spreading center |
Okinawa Trough |
27.5481 |
126.9895 |
1600 |
1988 submersible Shinkai 2000; 1987 plume only |
SPOT, Hatoma Knoll |
active, confirmed |
back-arc spreading center |
Okinawa Trough |
24.8550 |
123.8410 |
1520 |
1999 submersible Shinkai 2000 |
SPOT, Yonaguni Knoll IV |
active, confirmed |
back-arc spreading center |
Okinawa Trough |
24.8490 |
122.7000 |
1385 |
2000 submersibles Shinkai 2000 and Shinkai 6500 |
Tangyin |
active, inferred |
back-arc spreading center |
Okinawa Trough |
25.0667 |
122.5667 |
1206 |
2014 likely by dredging or ROV during the HOBAB3 cruise on R/V Kexue |
Tarama Knoll |
active, confirmed |
back-arc spreading center |
Okinawa Trough |
25.0916 |
124.5416 |
1990 |
2009 ROV HyperDolphin |
Yokosuka |
active, confirmed |
back-arc spreading center |
Okinawa Trough |
25.2638 |
124.3733 |
2190 |
2016 ROV Kaiko; 2014 plume only |
Yoron Hole |
active, confirmed |
back-arc spreading center |
Okinawa Trough |
27.4916 |
127.5333 |
590 |
2010 ROV Hyperdolphin |