West Rota Vent



Latitude: 14.325οN                  Longitude: 144.833οE             Depth: 309 m bsl

West Rota is a very large caldera on the Mariana arc, is approximately 8 km in diameter. Studies conducted in 2003 at West Rota revealed fluid enrichments in both Mn and Δ3He within the caldera (Stern et al., 2008), and later found that the vent is weakly active (Resing et al., 2009). Detailed ROV surveys in 2004 and 2005 discovered small patches of low-temperature venting at the base of the SE caldera wall (Stern et al., 2008). Apart from the chemistry, biodiversity of W Rota includes anemones and crinoids (Submarine Ring of Fire, 2004).

Table 1: Operations history for W Rota vent

Ship/ Platform Operation Year Dive Number References
NT 0517 R/V Natsushima/  Hyper-dolphin Not found 2005 October HPD#0482 to HPD#0484, HPD#0488, HPD#0489 NT05-17 cruise report
TN-153 R/V T. G. Thompson EM 300 multibeam; CTD Verical cast 2003 February – March Not found Submarine Ring of Fire 2003
TN-167 R/V T. G. Thompson/ ROPOS CTD tow-yo, CTD vertical cast, EM 300 2004 February – March R785 Submarine Ring of Fire 2004

Table 2: Vent activity and host rocks

Activity and host rocks References
Activity Extinct/ Dormant Embley et al., 2007
Host Rocks Basalt, Andesite and Dacite

Embley et al., 2007;

Stern et al., 2008

Table 3: Vent fluid characteristics

Vent Fluids References
Temperature (οC) Low T (<~100 οC) Embley et al., 2007
ΔpH 0.006 Resing et al., 2009
Composition Small Fe, Mn, and 3He Resing et al., 2009
TDMn (nM) 12 Resing et al., 2009
TDFe (nM) 12 Resing et al., 2009
Δ3He (fM) 0.12 Resing et al., 2009

* ΔpH – Measured relative to the regional background; Δ3He – Measured above the background.

Table 4: Vent Biology

General name Phylum Order/ Class References
Anemone Cnidaria Submarine Ring of Fire, 2004
Stalked Crinoid Echinodermata Crinoidea Submarine Ring of Fire, 2004


Video Links:


  1. Embley, R. W., Baker, E. T., Butterfield, D. A., Chadwick, W. W. Jr., Lupton, J. E., Resing, J. A., de Ronde, C. E. J., Nakamura, K., Tunnicliffe, V., Dower, J. F., Merle, S. G., 2007. Exploring the submarine ring of fire: Mariana Arc- Western Pacific, Oceanography 20, 68–79.
  2. Resing, J. A., Baker, E. T., Lupton, J. E., Walker, S. L., Butterfield, D. A., Massoth, G. J., Nakamura, K., 2009. Chemistry of hydrothermal plumes above submarine volcanoes of the Mariana Arc. Geochemistry, Geophysics, Geosystems 10 (2), doi:10.1029/2008GC002141.
  3. Stern, R. J., Tamura, Y., Embley, R. W., Ishizuka, O., Merle, S. G., Basu, N. K., Kawabata, H., Bloomer, S. H., 2008. Evolution of West Rota Volcano, an extinct submarine volcano in the southern Mariana Arc. Evidence from sea floor morphology, remotely operated vehicle observations and 40Ar-39Ar geochronological studies. Island Arc 17 (1), 70-89.

Website References:

  1. JAMSTEC (Japan Agency for Marine Earth Science and Technology) E-library of Deep-sea Images (JEDI) (accessed 10/03/2015)
  2. Submarine Ring of Fire 2003 (accessed 10/03/2015)
  3. Submarine Ring of Fire 2004 (accessed 10/03/2015)

Cruise Reports:

  1. Natsushima cruise report NT05-17 (accessed 2/27/2017)
  2. Submarine Ring of Fire 2003 (accessed 2/27/2017)
  3. Submarine Ring of Fire 2004 (accessed 2/27/2017)