The last 9.0 strength earthquake off the Oregon coast was in January, 1700. Looking at 9 earthquakes since the time of Christ, approximately every 300 years one of these quakes hits.
Obviously, the next one is due soon based on the periodicity of previous events. The Emergency Planning Representative said due to the size of the earthquake, there likely would be no power and no official warnings. The large tsunami similar to Japan's 2011 event will hit the Oregon coast as soon as 15 minutes after the earthquake stops. In other words, the earthquake IS the tsunami warning.
The average Oregon resident will wait for the government to tell them a tsunami is coming. Many of the towns on the Oregon coast are located near rivers, just above sea level.
Based on the average person out here according to what I heard, they expect massive loss of life when the next big one happens. The Emergency Plan rep showed a video with the Japanese in 2011 ignoring warnings and watching the tsunami flood their town AND then they ran. MANY of them didn't make it.
Subduction zone earthquakes are the most likely to produce tsunamis although landslides and thrust faults can as well (a subduction fault is actually a special case of a thrust fault). There is a long zone offshore in the pacific NW and will be a bad one. Signs of the last one can be found up the Coos River among other places. Looking up at the deposits the last tsunami made is just plain scary.
Many people living in tornado alley also have a lackadaisical attitude towards alarms. Here is Oregon’s plans...
http://www.oregon.gov/dogami/pages/earthquakes/coastal/tsubrochures.aspx
I always think Biblically about this stuff. I was wondering if the Great Earthquake is what takes out all the coastal cities that are prophesied against.