Acoustic and In-situ Observations of Hydrothermal Discharge at ASHES
Vent Field: an OOI Cabled Array Case Study
Abstract
The Cabled Observatory Vent Imaging Sonar (COVIS) was initially
installed on the Ocean Observatories Initiative’s Cabled Array (OOI-CA)
observatory at ASHES hydrothermal vent field on Axial Seamount in July
2018. COVIS recorded the acoustic backscatter from the water-column
plumes formed above hydrothermal sources and the seafloor within the
sonar’s field-of-view until Oct 2018, when an instrument malfunction
suspended regular data-collection procedures. In July 2019, COVIS was
redeployed after repairs and has since been collecting data at full
capacity. Here, we present a comprehensive analysis of the acoustic
backscatter data recorded by COVIS along with the in-situ temperature
measurements in 2018 and 2019. The results demonstrate significant
influences of ocean tides and bottom currents on diffuse hydrothermal
discharge within ASHES. In addition, comparison with local seismicity
shows a positive correlation between diffuse hydrothermal venting and
the seismic activity in the vicinity of the vent field, which provides
evidence for an intimate connection between hydrothermal activity and
geological processes during the dynamic period leading up to the next
eruption of Axial Seamount. Overall, our results showcase the
capabilities of underwater acoustic techniques as remote-sensing tools
for long-term, quantitative monitoring of seafloor hydrothermal
discharge.