Paleotsunami Inundation of a Beach Ridge Plain: Cobble Ridge Overtopping and Interridge Valley Flooding in Seaside, Oregon, USA

Figure 1

Location map of Seaside (boxed study area) at the southern end of the Clatsop beach-ridge plains (bold shoreline), located south of the Columbia River mouth. The study area is located near the center of the Cascadia subduction zone (inset) that extends ~1,000 km from Vancouver Island in British Columbia to northernmost California. The offshore deformation front of the subduction zone is shown by a bold dashed line. The Seaside population, up to 50,000 people, is expected to have ~25 minutes to evacuate following seismic shaking, before the onset of tsunami inundation [6]. Map coordinates include reference longitude and latitude and UTM Northings at 10 km intervals for the Clatsop Plains.