Clatsop County residents and guests are at risk of being impacted by tsunamis, a series of waves usually caused by an undersea earthquake. As these waves enter shallow water near land, they increase in height and can cause great loss of life and property damage.
The first wave is often not the largest. Additional waves may be spaced many minutes apart and can continue arriving for several hours.
Tsunamis may be caused by an earthquake near shore, such as one generated at the Cascadia fault line, or they may be created by a quake hundreds or thousands of miles away.
It Matters Where You Are When a Tsunami Strikes
Near the Shore
In the case of a near-shore earthquake, the first wave comes quickly. It will reach the coast in 15 to 20 minutes. That means you have to get to high ground immediately once the quake ends. Do not wait for a siren or other official warning.
Distant or Far Away Earthquakes
A tsunami generated by a distant earthquake may take several hours to reach the Oregon Coast. Emergency officials will provide warnings through local radio broadcasts. Some local communities also have their own public warning systems. If you hear a solid three-minute siren blast, that’s the signal to evacuate. Distant tsunamis are generally smaller than those generated nearer to shore, but can still cause considerable damage
Signs of a Tsunami
A sign that a tsunami is coming often is a sudden change in the sea level. If you are at the beach and see the sea level suddenly rise or fall, quickly get to higher ground.
New Tsunami maps have been released by The Oregon Department of Geology and Mineral Industries (DOGAMI). They show tsunami inundation zones, evacuation routes and gathering points for communities in Clatsop County.
These maps are based on the latest scientific data, identifying areas at risk of inundation from a projected worst-case local, Cascadia zone tsunami, and a worst-case distant generated tsunami.
Maps are available for:
- Arch Cape
- Cannon Beach
- Seaside & Gearhart
- Sunset Beach & Del Rey Beach
- Youngs River Valley
To find out more go DOGAMI’s Tsunami Clearinghouse website.
Where do I evacuate?
- Go to an area 50 feet above sea level, if possible.
- If you are in a multistory building and don't have time to travel to high ground, go to an upper level of the home or building.
- If you are on the beach and cannot get to high ground, go inland as far as you can.
- Go on foot if possible, particularly if an earthquake has caused damage to roads, power lines, and resulted in significant debris.
- Do NOT return to shore after the first wave – tsunamis usually occur as a series of many waves. Wait until the official tsunami warning or alert has been lifted.
- Never go to the coast to watch a tsunami. Tsunamis move faster than a person can run.
Evacuation Signage and What They Mean
Tsunami evacuation routes were developed to assist coastal residents and visitors find safer locations in case of an earthquake and tsunami.
Evacuation signs have been placed along roadways to let you know if you are entering or leaving a tsunami zone and some direct you on how to get to higher ground. In some places, there may be more than one way to reach safer areas. These routes may be marked with several signs showing additional options for evacuation.
Plan and Prepare
- Find out if your home, place of work and other locations you frequent are within the tsunami inundation zone. These are the areas deemed vulnerable to flooding in the event of a tsunami. Go to the DOGAMI Tsunami Clearinghouse website to find evacuation maps that include sites you and your family frequent.
- Know your route to safety. DOGAMI’s tsunami maps show evacuation routes away from areas subject to possibly inundation, as well as designated assembly areas out of the flood zones.
- Have your disaster kit ready to take with you.
- Ready Emergency Supply List
- "Beat the Wave" Tsunami Evacuation Map - SEASIDE, OREGON - SOUTH
- "Beat the Wave" Tsunami Evacuation Map - SEASIDE, OREGON - NORTH
- Tsunami Evacuation Analysis of Astoria and Nearby Unincorporated Communities, Clatsop County, Oregon
- Tsunami Evacuation Analysis of Cannon Beach, Arch Cape, and Falcon Cove, Clatsop County, Oregon
Public Service Announcements
- Tsunami 101
- Kids Tsunami Preparedness Video Contest Winner
- Japan Earthquake/Tsunami PSA
- CG Simulation of Tsunami Aims to Spur Awareness