Acoustic and in-situ observations of hydrothermal discharge at ASHES vent field

Abstract

The Cabled Observatory Vent Imaging Sonar (COVIS) was installed on the Ocean Observatories Initiative’s Cabled Array observatory at ASHES hydrothermal vent field on Axial Seamount in July 2018. The acoustic backscatter data recorded by COVIS, in conjunction with in-situ temperature measurements, are used to investigate the temporal and spatial variations of hydrothermal venting within COVIS’s field-of-view. Areas in which diffuse hydrothermal flow is significant are identified by maps made using the standard deviation of the phase change between pings separated in time by fractions of 1 s. The results demonstrate significant influences of ocean tides and bottom currents on diffuse hydrothermal discharge. Comparison with local seismicity shows a small positive correlation between the areal coverage of diffuse hydrothermal discharge and the seismic activity in the vicinity of the vent field. This finding reveals an intimate connection between hydrothermal activity and geological processes during the dynamic period leading up to the next eruption of Axial Seamount. [Work sponsored by NSF.]