Bubbles Without End: Unmatched Seep Observations off the Cascadia Margin from Ocean Networks Canada's NEPTUNE Observatory at Clayoquot Slope

Abstract:

Ocean Networks Canada has been acquiring sonar backscatter data from a permanently installed multibeam sonar on the ocean floor at a seep site called Gastown Alley that appears to have been continually bubbling since the installation 2014. Changes in bubbling intensity are correlating with tidal pressure, as was determined from a previous two-year observation record from a nearby site Bubbly Gulch with more intermittent bubble activity. However, there are longer-term, month-long, variations that have yet to be explained. Comparisons with colocated environmental observations such as temperature, currents, or ground shaking induced by storms or earthquakes have not shown to consistently influence the bubbling intensity, although some exceptions apply. We will present nine years of data and show detailed examples of bubble variations together with various other environmental observations and invite the audience to speculate with us what this could mean and what else should be considered. Ocean Networks Canada (https://www.oceannetworks.ca) has been operating ocean observatories since 2006, both ocean-based and coastal, and all data are free and open access at https://data.oceannetworks.ca.