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Seaside, Oregon Harry Yeh Oregon State University Seaside, Oregon, Tsunami Pilot Study – Modernization of FEMA Flood Hazard Maps A Tsunami Pilot Study was carried out in the Seaside area to develop a Tsunami Hazard Analysis methodology as part of FEMA's Map Modernization Program.
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Seaside, Oregon Harry Yeh Oregon State University
Seaside, Oregon, Tsunami Pilot Study – Modernization of FEMA Flood Hazard Maps • A Tsunami Pilot Study was carried out in the Seaside area to develop a Tsunami Hazard Analysis methodology as part of FEMA's Map Modernization Program. • The Seaside area was chosen because it is typical of many coastal communities in the Pacific Northwest Coast, and because State agencies and local stakeholders expressed considerable interest in mapping the tsunami threat to this area. • Concern with tsunamis generated by Cascadia subduction.
Examples of co-seismic vertical sea floor displacement Tsunami sources of Cascadia Subduction Earthquake
Discovery of Great Cascadia Earthquake on January 26, 1700 • Paleo-tsunami deposits, radio-carbon and tree ring dating of vegetation killed by an earthquake along Pacific Northwest coast (1987, Science) • Historical (“OLD”) documentation of coastal flooding in Japan (1996, Nature) • Legends and myths of Pacific Northwest Native Americans.
Paleo-tsunami deposits At Willapa Bay, Washington Old Japanese Documents on Coastal Flooding on January 1700 (Atwater, 2005)
The 1964 Great Alaskan Tsunami Inundation in Seaside Tsunami Deposits
Tsunami Deposits found in Seaside Older Events 1964 Akaska 1700 Cascadia
Map of 100- and 500-year flood zones overlaid on FEMA Flood Insurance Rate Maps. Seaward limit is mean lower low water. Line showing extent of deposits from tsunami generated by 1700 Cascadia earthquake is included for comparison. Evacuation distance to high-ground safe haven from the beach is approximately 2 km.
Tsunami Shelters Nishiki Tower in Japan
Demonstration of the effectiveness of tsunami shelters Two Tsunami Shelters No Shelter
Existing well-engineered reinforced concrete structures might be used as shelters