Our North Oregon Coast area is prone to earthquakes and thus to the threat of tsunamis as well. There are two different kinds of earthquake and tsunami threats — a tsunami caused by a local earthquake we would experience as shaking ground, and a tsunami caused by a distant earthquake that we would not feel. In both events, it is essential to follow the guidelines for evacuation of the inundation zones.

Jeff Rubin, PhD, Emergency Manager, Tualatin Valley Fire & Rescue, presented on September 16, 2017, a talk on understanding earthquakes and tsunamis in order to properly prepare to the community of Manzanita, Oregon.  His entire presentation may be view online.  Cascadia and Beyond: Before and After.

A local subduction zone earthquake of unimaginable power could happen at any time, without warning.

The ground will shake so hard we can’t stand up, lasting for three to five minutes. This quake may destroy bridges, roads, power poles and lines, water and sewer lines, leaving an unimaginable mess.

Then, the sea will pull out, and a few minutes later the tsunami — a wall of water and debris 30 to 80 feet in height — will roll inland. It may bring ships and barges to land, toss boats and logs like toothpicks, move cars and trucks like toys, and devastate buildings. Both inbound and outbound waves, one after another, will do their damage for hours.

The combination of local earthquake and tsunami may leave us without shelter, isolated and self-reliant for a week or several weeks until significant outside help can arrive. However, this powerful disaster is very survivable if we prepare ahead, then act calmly and quickly when the quake and tsunami strike.

If the ground shakes

If the ground shakes, drop, cover, and hold on. Drop to the floor, take cover under a sturdy desk or table, and hold on to it firmly. Be prepared to move with it until the shaking stops.

If you are not near a desk or table, drop to the floor against the interior wall and protect your head and neck with your arms.

Avoid exterior walls, windows, hanging objects, mirrors, tall furniture, large appliances, and kitchen cabinets with heavy objects or glass. Do not go outside!

When the shaking stops

You may have only 15 to 20 minutes to make it to high ground (approximately 100 feet or more above sea level) before a tsunami reaches our shores.

As soon as you can stand and stay on your feet, if you or your home are in the tsunami inundation zone, grab your GoBag and evacuate with your family immediately on foot to high ground (see map for inundation zones and your nearest high-ground emergency assembly area).

Do not drive, as streets will be impassible, buckled or blocked by broken structures, trees, poles, stranded cars and debris.

Stay at high ground until the all-clear sounds, or until 12 hours pass without further damage.

Above the inundation zone

Whether you experience a local or distant earthquake, if you are above the tsunami inundation zone, check your house or building — is it safe to occupy? When you and your family are safe, retrieve your shelter-in-place kit and follow your Prepare Your Neighborhood plan.

A less severe threat is the distant earthquake and tsunami. A distant earthquake is an earthquake that happens somewhere else, and you won’t feel the quake. Any resulting tsunami waves will take longer to arrive and be somewhat shallower.

In this scenario, you will likely receive notification that an earthquake has happened at some distance away from local first responders canvassing with loudspeakers, on NOAA radios, on TV and AM/FM radio stations, or even via Civil Air Patrol announcements from the sky.

When notified of a distant earthquake and threat of tsunami

You may have several hours to evacuate before a tsunami strikes our area.

Take these actions:

  • Don’t panic.
  • Get off the beach.
  • Get your things together, plan to be gone for at least 12 hours, and go to high ground.
  • If you are at high ground, stay there.
  • Remain out of the inundation area until the all clear is issued by local emergency officials.

Power, telephone service, radio and TV stations and other infrastructure will likely remain in place until the tsunami arrives.

If a tsunami does hit the area following a distant earthquake, these waves will likely be lower in height than those caused by a local earthquake and tsunami. However, there may be several waves, with subsequent waves being higher than the first.

Above the inundation zone

Whether you experience a local or distant earthquake, if you are above the tsunami inundation zone, check your house or building — is it safe to occupy? When you and your family are safe, retrieve your shelter-in-place kit and follow your Prepare Your Neighborhood plan.

For more information about preparing for and responding to earthquakes and tsunamis in the Nehalem Bay area, please download “Earthquakes and Tsunamis: What You Need to Know” in English or Spanish and share it with your family and guests to our area.

You can also download “Living on Shaky Ground: How to Survive Earthquakes and Tsunamis in Oregon” in English or Spanish.

Read DOGAMI’s “Cascadia Subduction Zone Earthquakes: A Magnitude 9.0 Earthquake Scenario”, which examines how the Pacific Northwest may fare after the next great “megathrust” earthquake and tsunami.

Earthquake Information

Check the latest earthquake information at the U.S. Geological Survey Earthquake Hazards Program. The site lists each recent quake; click on each quake to view additional details.

For more information, visit ready.gov and American Red Cross.

Tsunami Information

Check the latest tsunami information at the West Coast Tsunami Warning Center:

  • Event Location shows where the quake centered
  • Travel Times shows times in hours from epicenter to our coastline
  • Alert Status shows warning, watch, advisory or “clear” for our coastline

Tsunami information usually comes in one of these forms:

  • Warning: Inundating wave possible; full evacuation suggested
  • Watch: Danger level not yet known; stay alert for more info
  • Advisory: Strong currents likely; stay away from the shore
  • Information: Minor waves at most; no action suggested

For more information, visit Oregon Tsunami Clearinghouse, ready.gov and American Red Cross.