What effects have storms on the compliant seafloor?
Ocean Networks Canada has recorded pressure and seafloor motion data that allow the correlation of storm waves and the corresponding seafloor compression induced by ocean waves. Over the years, impressive storms and large waves have passed across Ocean Networks Canada's offshore NEPTUNE observatory and long records of wave action and seafloor motion are now available. The stiffness of the seafloor determines how compliant the seafloor is in reaction to changing water pressure due to the passing ocean surface waves. The detection of this impressive behaviour requires extremely sensitive instruments. Ocean Networks Canada's offshore NEPTUNE observatory has bottom pressure recorders (BPRs) and broadband seismometers located at various locations both on the continental shelf and slope, the deep-sea basin, as well as an ocean spreading ridge. Careful analysis of long time series will results in seafloor compliance values and allow for a site characterization in terms of state of the seafloor.
Furthermore, the change of seafloor compliance over time will provide insights to subsurface changes. For example, locations where gas hydrates occur may exhibit compliance changes due to increased or decreased presence of this ice-like material that hardens the host sediments. Similarly, at ocean spreading ridges the relatively shallow magma chambers influence the seafloor stiffness when they well up or down. The result of this study can be extremely useful for the gas hydrate or hydrothermal vent communities to better understand their observations when they relate them to what happens beneath the surface.