then used Urashima
to undertake the first detailed morphological study of hydrothermal
systems in the Mariana Trough. Nakamura et al. (2013) subsequently
focused on AUV mapping data from a 5 × 5 km area across one of
theseMariana Trough sites, the Pika hydrothermal vent site. A new hydrothermal
vent site (named Urashima, after the AUV) was inferred to
be adjacent to the Pika site based on AUV magnetisation and MBES
data, and active venting into the water column at this location was imaged
using 120 kHz SSS data (Fig. 5) and confirmed with ROV imaging.
These recent studies using Urashima highlight the ability of AUVs not
only to map existing and discover new hydrothermal vent sites, but
also to confirm active venting at the seafloor using SSS imagery. This
more direct method overcomes some of the problems associated with
geochemical mapping of diffuse hydrothermal plumes, e.g. dispersal
by deep bottom currents (German et al., 2008b), and aids identification
of closely spaced vent sites.