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TIM-Doug-08, Tsunami Inundation Maps for Umpqua River East, Douglas County, Oregon
Order publication CD-ROM, $10, from Nature of the Northwest.
Overview of TIM series publications, TIM index map, anticipated modeling and mapping schedule, and evacuation brochures made from TIM maps.
About this publication:
2 PDF plates. Scale 1:10,000. Plate dimensions: 50 x 34 inches. News release.
The Oregon Department of Geology and Mineral Industries (DOGAMI) has been identifying and mapping the tsunami inundation hazard along the Oregon coast since 1994. In Oregon, DOGAMI manages the National Tsunami Hazard Mitigation Program, which has been administered by the National Oceanic and Atmospheric Administration (NOAA) since 1995. DOGAMI’s work is designed to help cities, counties, and other sites in coastal areas reduce the potential for disastrous tsunami-related consequences by understanding and mitigating this geologic hazard. Using federal funding awarded by NOAA, DOGAMI has developed a new generation of tsunami inundation maps to help residents and visitors along the entire Oregon coast prepare for the next Cascadia Subduction Zone (CSZ) earthquake and tsunami.
Plate 1, Local Source (Cascadia Subduction Zone) Tsunami Inundation Map
Plate 1 displays the output of computer models representing five selected tsunami scenarios, all of which include the earthquake-produced subsidence and the tsunami-amplifying effects of the splay fault. Each scenario assumes that a tsunami occurs at Mean Higher High Water (MHHW) tide; MHHW is defined as the average height of the higher high tides observed over an 18-year period at the Yaquina Bay (Central Coast Model) tide gauge. To make it easier to understand this scientific material and to enhance the educational aspects of hazard mitigation and response, the five scenarios are labeled as “T-shirt sizes” ranging from Small, Medium, Large, Extra Large, to Extra Extra Large (S, M, L, XL, XXL). The map legend depicts the respective amounts of slip, the frequency of occurrence, and the earthquake magnitude for these five scenarios.
Plate 2, Distant Source (Alaska-Aleutian Subduction Zone) Tsunami Inundation Map
Alaska-Aleutian Model Specifications: DOGAMI modeled two distant earthquake and tsunami scenarios involving M9.2 earthquakes originating near the Gulf of Alaska. The first scenario attempts to replicate the 1964 Prince William Sound event, and the second scenario represents a hypothetical maximum event. This maximum event is the same model used by the U.S. Geological Survey (USGS) in their 2006 tsunami hazard assessment of Seaside (TPSW, 2006). This model uses extreme fault model parameters that result in maximum seafloor uplift; nearly twice as large as in the 1964 earthquake. The selected source location on the Aleutian chain of islands also shows higher energy directed toward the Oregon coast than other Alaskan source locations. For these reasons the hypothetical “Alaska Maximum” scenario is selected as the worst case distant tsunami scenario for Oregon. For more detailed information on the tsunami models and methodologies used, please see DOGAMI Publication Special Paper 43 (Witter and others, 2011).