Coastal Hazards
_{Tsunami hazard maps for the Oregon coast and community evacuation brochures}

2-16-10 DOGAMI news release - Report released on tsunami evacuation building workshop (Regarding Open-File Report O-10-02, Tsunami Evacuation Building Workshop, September 28-29, 2009, Cannon Beach, Seaside, and Portland, Oregon, compiled by Yumei Wang; 35 p. text, plus 200 p. PowerPoint slides; CD, $15) | order

2-12-10 DOGAMI news release - New multi-year tsunami mapping and outreach program comes to the Oregon Coast: Several coastal communities selected to become TsunamiReady, TsunamiPrepared over the next year | TsunamiReady Program




Tsunami! Know how to survive on the Oregon coast (PDF)

October 17, 2003 -Tsunami preparedness guide for coastal lodging facilities released (news release PDF) | zipped file of Open-File Report O-03-04 publication files (97 MB)

Open File Report O-03-05 - Development in Oregon’s Tsunami Inundation Zone: Information Guide for Developers and Local Government by Dennis Olmstead, Oregon Department of Geology and Mineral Industries, 2003, $10.

Open-File Report O-03-06 - Tsunami Sign Placement Guidelines by Mark Darienzo, Oregon Emergency Management, 2003, $10.

This information is from Open File Report 95-67. To read the complete report in PDF form (12 MB), click here.

The tsunami hazard maps were produced to help implement Senate Bill 379 (SB 379), which was passed by the 1995 regular session of the Oregon Legislature.

SB 379, implemented as Oregon Revised Statutes (ORS) 455.446 and 455.447, limits construction of new essential facilities and special occupancy structures in tsunami flooding zones. The focus of the maps is therefore on implementation of this public safety bill and not on land use or emergency planning.

"These maps are not intended for emergency evacuation purposes and do not necessarily represent tsunami inundation from a worst-case event. Recommended evacuation areas are illustrated on evacuation brochures produced for selected parts of the Oregon coast. Potential flooding for a worst-case tsunami event is also depicted on tsunami inundation maps produced from detailed computer simulations of tsunami flooding.

These maps are available for selected population centers. Click here to go to the evacuation brochures.

Tsunamis are caused by any large-scale disturbance of the sea floor. In nature these disturbances are generally caused by faulting, landslides, or volcanic eruptions. This project addresses only the most common cause, the simultaneous uplift and subsidence of the sea floor accompanying undersea earthquakes on large fault zones termed “subduction zones”. The shape of the deformed sea floor after an earthquake is transmitted to the overlying sea surface, forming the initial tsunami wave. Waves so generated can arrive at nearby coastlines in minutes, causing extensive damage and loss of life.

These subduction zone earthquakes also typically cause landslides which can greatly amplify the tsunami run-up should they occur under the sea or slide from land into water. This latter hazard is not directly addressed here but could be an important consideration when adding factors of safety for evacuation planning.

Scientific findings of the last several years have shown that the Oregon coast is vulnerable to great (Magnitude 8-9) earthquakes
that can occur on the offshore Cascadia subduction zone fault system .

The estimated chance in the next 50 years of a great subduction zone earthquake is between 10 and 20 percent, assuming that the recurrence is on the order of 400 ± 200 years and that the last one occurred about 300 years ago.

• Learn more about the science of tsunamis
  

• Links to tsunami hazard risk reduction resources
  
  
• Coastal hazards publications from DOGAMI
  
  
• NOAA's Tsunami page
  
  
• West Coast and Alaska Tsunami Warning Center
  
  
• International Tsunami Information Centre
  
• Tsunami links for kids
  
  
• Learn more about other hazards along the Oregon coast
  
  
• Earthquake education and resources for risk reduction and mitigation
  
  
• Oregon at Risk - from the winter, 2001 issue of Cascadia
  
  
• Put together an emergency kit

• Learn more about tsunamis
  
  
• Tsunami Links
  
  
• Publications and data homepage
  
  
• Coastal hazard publications
  
  
• Complete DOGAMI publications list (PDF)
  
  
• Northwest Geology News
  
  
• Map links
  
  
• Data Links