We often hear from one expert (Chris Goldfinger) when it comes to how likely it is Portland will experience damage from an earthquake.
Let's take a step back for a moment to hear from Professional Engineer Andrew J McCann, who had this to say on the matter recently:
Education is the key to enlightenment.
Earthquakes occur on a daily basis - most very small, some very large.
Will a quake occur beneath Portland - only minor ones if any at all. Which means we will not bare the full force of a quake in our area of the world. When the news writes a quake of 9.5 will hit Portland - that gets everyone's attention, even in New York City! However, that is the maximum anticipated quack at the epicenter - that point over the quake it's self! Not what we will feel in Portland.
Will Major quakes occur around Portland - that's a broad question - the closest possible quake would come from the Cascadia Subduction zone 350 miles away - and/or Mount Hood located approximately 78 miles from the center of Portland - estimated maximum at a 9.5 at the Epicenter at the Casdadia seduction line. So we would probably see much less damage than occured in Santiago Chile; and nothing like the damage seen in the coastal towns of Chille located just 30 miles from the quakes epicenter.
Straight of Juan de Fuca Tectonic Plates - AKA Juan De Fuca Plate is approximately 1000 miles from the center of down town Portland. and extends from entry to the straight of Juan de Fuca, out into the pacific about 1000 miles, then back towards Eureka, California.
While the massive quakes off the coast of Japan and Chille damaged local towns and cities, the real damage came from the Tidal Waves/Tsunami's that occurred as a result of the quake. Note: Japanese quake was approximately 60 miles offshore while the Chilaen quake was only 20 miles off shore - and we are 78 miles from Mount Hood and 800 miles from the Straight of Juan De Fuca fault!
Tsunami's are deadly for those living on the coast. However, studies by Oregon State University have noted that the tide would rise to a point 6 feet above flood stage in Astoria and by Longview - no change would be noted. Besides, I don't think a 100 foot high wave would make it over the coast range! Even the Tsunami free zones are marked in blue located on the west side of highway 101 thru Newport, Oregon. So lets not think/worry any more about a tidal wave taking out the bridges and washing away downtown Portland.
Most quake's intensity is strongest within the first 20 to 40 miles of the epicenter - where most of the cities have major damage. So being 78 miles from mount hood 300 miles from the Cascadia Subduction zone gives us a lot of breathing room. Also, death tolls and injuries are minimal due to the rocking and rolling of the quake; while most people and homes are damaged/lost from the following tidal wave.
While I concur with our leaders that we must do something, the probability of a quake from the Mount Hood area is fairly minimal; and the Cascadia Zone - 10% probability of occurring in the next 50 years. We should not make a Knee Jerk reaction to something that requires thought and planning.
We should think about what we can do over the next 50 years to limit impact of falling structures, saving lives and take into account the cost to the general public.
My family and I own 5 of these URMB structures. However, as a Professional Engineer I must position myself to perform the duties I'm charged with: To Safe Guard the Public followed by Property and well being of all that there is.
We must prioritize what is most important, allocating resources in a logical manor and using methodical methods to prepare for what ever may come - whether it be an eruption, tidal wave, plane wreck or earthquake.
Last but not least - listen and watch the animals, as for centuries, people have noted wild life moving in droves to safety, hours before a major earthquake/tsunami occurs - would it not be more prudent/cost effective to place locators on all animals around Mount Hood and along the Pacific Coast; then notify people in those danger zones of an impending Quake or Tsunami???