TSUNAMI HAZARDS FOR ASTORIA-WARRENTON MAPPED

Portland, Oregon: Tsunamis are one of the most dangerous natural disasters that could affect Warrenton and Astoria. New maps are now available from the Oregon Department of Geology and Mineral Industries (DOGAMI) to help these communities prepare for tsunamis.

"These map shows how three different tsunamis might affect the area," explains Dr. George Priest, a coastal hazards geologist with DOGAMI, who prepared the maps. "Tsunamis are a series of waves generated by undersea earthquakes, so we’ve used computers to simulate three different local earthquakes and the tsunamis they might cause. These simulations were used in conjunction with field observations to produce the maps."

Scientific research in the past ten years has established that great (magnitude 8 to 9) undersea earthquakes off the Oregon coast cause devastating tsunamis to strike every 300–600 years. "The last event was almost 300 years ago, on January 26, 1700, so another could happen at any time," Priest says. "The earthquake itself might last up to four minutes, damaging roads, bridges and other facilities. Within about 30 minutes after the start of the earthquake the first of several large high-velocity tsunami waves would hit this part of the coast. It’s important that people know the safest way to go to high ground or at least go as far inland as possible."

Officials from DOGAMI and Oregon Emergency Management (OEM) are working with coastal cities to identify evacuation routes. The new maps and similar maps will help them find routes that will be least affected by tsunamis. Signs to mark the routes so that residents and tourists can easily find them are available from DOGAMI and OEM.

DOGAMI is also coordinating tsunami education as part of a comprehensive strategy to reduce risk. Educational efforts include materials such as videotapes and curriculum for schools to teach children how to react, information signs on beaches and cards to be placed in motel rooms. The maps, which show city streets and tsunami flooding areas, were produced by DOGAMI in partnership with a community advisory committee.

Because of the potential loss of life and property from these events, many government agencies have contributed to these maps and will continue to work with the communities on risk reduction, outreach and hazard mitigation. The Oregon Graduate Institute of Science and Technology and the National Oceanic and Atmospheric Administration (NOAA) provided scientific research to produce the maps. NOAA and the Federal Emergency Management Agency (FEMA) funded the project.

The publications, Tsunami Hazard Map of the Astoria Area, Clatsop County, Oregon, DOGAMI map IMS–11, and Tsunami Hazard Map of the Warrenton Area, Clatsop County, Oregon, DOGAMI map IMS-12, are available for $10 each from the Nature of the Northwest Information Center, 800 NE Oregon Street #5, Portland, 97232, (503) 872-2750; and the DOGAMI field offices: 1831 First Street, Baker City, 97814, (541) 523-3133; and 5375 Monument Drive, Grants Pass, 97526, (541) 476-2496.

The Oregon Department of Geology and Mineral Industries is headquartered in Portland and is an independent agency of the State. It has a broad responsibility in developing a geologic and engineering understanding of natural hazards, then applying this information to help mitigate the risks of earthquakes, landslides, floods and tsunamis. The Department is also the lead state regulatory agency for mining, oil, gas and geothermal exploration, production and reclamation.

For more information on The Department of Geology and Mineral Industries’ current projects, contact James Roddey at 800 NE Oregon St., Portland, OR 97232, (971) 673-1555, ext. 242, or DOGAMI field offices at:

1831 First Street, Baker City, (541) 523-3133

5375 Monument Drive, Grants Pass, (541) 476-2496

Mined Land Reclamation Program, 1536 Queen Avenue SE,
Albany, OR 97321, (541) 967-2039.