Figure F1. A. Map of the Cascadia subduction zone. The box shows the location of the topographic map shown in B. B. Bathymetric map of the Cascadia accretionary prism in the vicinity of Hydrate Ridge. NHR = north Hydrate Ridge summit, SHR = south Hydrate Ridge summit; SEK = Southeast Knoll. Locations of the 3-D seismic survey and the 2-D seismic profiles shown in Figure F2 are also indicated. C. Bathymetric map of southern Hydrate Ridge. Locations of the planned drill sites are also shown (solid circles = primary sites, open circles = alternate sites). EM300 bathymetric data are from Clague et al. (2001).