Clatsop County's Natural Hazards Mitigation Plan adequately describes the causes and characteristics of tsunami hazards, as well as the previous occurrences of tsunami events within the region. In 1995, The Department of Geology and Mineral Industries (DOGAMI) conducted an analysis resulting in extensive mapping along the Oregon Coast. The maps depict the expected inundation for tsunamis produced by a magnitude 8.8 to 8.9 undersea earthquakes. The tsunami maps were produced to help implement Senate Bill 379 (SB 379), which was passed during the 1995 regular session of the Oregon Legislature. SB 379, implemented as Oregon Revised Statutes (ORS) 455.446 and 455.447, and Oregon Administrative Rules (OAR) 632-005, limit construction of new essential facilities and special occupancy structures in tsunami flooding zones.
Because Cannon Beach was the focus of a pilot-mapping project, the recent inundation mapping had no significant changes for Cannon Beach. Using the latest advances in mapping technology (LIDAR), computer technology and computer modeling. The new maps will be scenario based, meaning that variations in inundation levels (given local or distant tsunamis) will be shown.
The extent of a tsunami event in Cannon Beach will depend on where the tsunami originated, and the size of the earthquake that produced the tsunami. Clatsop County appropriately describes the probability of a tsunami event for Cannon Beach. Geologists predict a 10-14% chance that a Cascadia tsunami will be triggered by a shallow, undersea earthquake offshore Oregon in the next 50 years. The forecast comes from evidence for large but infrequent earthquakes and tsunamis that have occurred on the Oregon coast every 500 years, on average.
A Cascadia Subduction Zone event will begin with a magnitude 9.0 near shore earthquake closely followed by a series of devastating coastal Tsunami waves. It can occur at any time and during any season. The challenge for Cannon Beach is how to provide shelter, water and food for up to 4 thousand survivors depending on the season. Through a series of tabletop exercises, Cannon Beach has developed a "Hub and Spoke" emergency management concept. With the Cannon Beach Emergency Operation Center as the "hub" and three-evacuation community support
sites as the spokes.
Based on a recently completed innovative pilot project, each evacuation support site will consist of two 20' shipping containers placed on a concrete pad. The pilot project containers are loaded with the following community resilience support items:
- Family Cache Containers
- Medical, administrative, and support equipment containers
- Tourist, Employee and Visitor Kits
Cannon Beach has three population demographics influenced by a Cascadia Subduction event. They are:
- Residents who live above the inundation line
- Residents who live below the inundation line
- Tourists, visitors and employees who work or temporarily reside below the inundation line
Oregons North Coast climate can present hypothermia as the primary danger long before water or food becomes an issue. Exercise outcomes measured resiliency, in terms of shelter first, water second and food last. Group 1 would most likely shelter in place leaving groups 2 and 3 as those most in need of initial support. Based on exercise outcomes Cannon Beach began an innovative cache container pilot project consisting of the following components:
- A support site consisting of two 20' shipping containers
- Family Cache Containers
- Tourist/EmployeeNisitor kits
- Medical, administration and equipment support containers
Each group was provided, at cost, storage containers in the form of 55 gallon drums, 30 gallon barrels or 5 gallon buckets for use as personal cache containers.
Each family determined how many cache containers they would need and packed them per their familys needs. Because group 3 could makeup the largest population segment Cannon Beach has developed an innovative Tourist/Employee/Visitor kit. It consists of a shelter system (poncho, space blanket, tube tent), water and food for 500 survivors.
The County estimates a 'high' vulnerability to tsunami hazards, which indicates that
at least 10% of the County's population and regional assets are likely to be affected by a tsunami event. This rating appropriately describes Cannon Beach's vulnerability as well. More than 50% of Cannon Beachs developed lands are within the tsunami inundation zone. This includes close to 1,000 residents, and more than 1,000 employees. Additionally, more than 25 overnight-tourist facilities are within the inundation zone.
Cannon Beach recognized the serious nature of the tsunami threat in the middle 1980s and the Fire District began the purchase and installation of warning sirens to mitigate the threat of massive loss of life along the beaches and in low lying areas of the community. The first sirens became operational in 1996 and still function today. The December 2004 quake near Sumatra made the value of these sirens clear to the rest of the world.
Since the siren installations, Cannon Beach has taken additional steps to help insure its survival when a tsunami strikes the area. Past and current activities include:
- Adding satellite phones and a BGAN Internet satellite receiver to the communication tools;
- Purchase of portable water tanks for emergency distribution of potable water;
- Constructing cache sites for storing personal, administrative, support tools and emergency medical supplies throughout the community;
- Establishing an Emergency Preparedness Committee;
- Sponsoring annual Tsunami Education Forums for community members;
- Printing and distributing informational brochures;
- Establishing designated shelters in the community and supplying them with emergency generators;
- Grading and maintaining an emergency helicopter landing pad;
- Wrote, adopted and updated emergency management plans;
- Established committees to address tsunami preparedness;
- Worked with local, state and federal agencies to better understand the tsunami hazard and prepare the community to deal with it;
- Worked with the community elementary school to implement evacuation plans and drills;
- Conducted seismic evaluations of the designated shelter sites;
- Stored County Health Dept. supplies in the Fire Station;
- Purchased a cache of blankets, food, water and shelter supplies for use following a tsunami;
- Created a Red Cross trailer that could hold disaster supplies;
- Established tsunami evacuation routes and sites;
- Met the objectives established by the National Oceanic and Atmospheric Administrations "Tsunami Ready" program;
Some of the mitigation projects still needing to be initiated and/or completed are the seismic upgrades to the two local bridges (to provide safe evacuation routes after a quake and before a tsunami arrives), relocation of the community elementary school to high ground, relocation of both local fire stations to high ground, creating vertical evacuation sites in the community, relocation of City Hall/Police Dept. facilities to high ground, and preparing emergency medical facilities to care for the injured following a tsunami.