Methane seep locations derived from water-column acoustic backscatter data collected along Cascadia Margin offshore Oregon and Northern California, 2018-2021

Between 2018-2021, the U.S. Geological Survey cooperated with NOAA to conduct multibeam echo-sounding surveys to map the seafloor along the Cascadia convergent margin, collecting acoustic bathymetry, backscatter and water column data. Rising bubbles emitted from methane cold seeps on the seafloor can be detected acoustically with this multibeam echo-sounding sonar, and this dataset contains the locations of 902 cold seeps found in Cascadia during these surveys. The multibeam echosounder surveys that collected these data were part of broader effort by the USGS Marine Geohazards Program to compile high-resolution bathymetric maps of the Cascadia Margin. These data are used to characterize the seafloor geomorphology to help understand geologic hazards posed by the megathrust fault and other tectonic features of the Cascadia subduction zone. Multibeam echosounding sonar used to map the depth and topography of the seafloor also captures anomalies in the water column above the seafloor, such as rising fluid bubbles that produce strong acoustic reflectance in the imaging sonar. Globally, vast reserves of methane are stored beneath the seafloor that can seep up into the water column and can be detected with multi-beam echo sounder. The seeps in this dataset were detected in the water-column acoustic backscatter data and recorded for the purposes of understanding patterns in the distribution of fluid seepage along the margin.