...So, there's an issue that I don't think is discussed as much as it should be given the scale & seriousness of the situation:
The Cascadia Subduction Zone, which was thought to be dormant / aseismic up until the late 80s because of a dearth of documented earthquakes in the region since European settlement, is now known to actually be a mega-thrust earthquake risk; a region that is only mostly silent because the plates lock together and build-up pressure over hundreds of years rather than decades before rupturing, sometimes across the entire fault line.
Events at this zone would likely mirror the event in terms of energy release seen off of Japan's coast in 2011 - and that quake killed over 15,000 people in Japan, even despite the rather staunch building codes & precautions taken by the state. British Columbia, Oregon & Washington, by comparison, have essentially zero
interesting earthquake preparation programs and little to no earthquake related building codes. The fact that the fault is usually so quiet (although you do certainly still feel tremors here on Vancouver Island once or twice a year) disguises the menace, making it far too easy to ignore and difficult to have a serious discussion about (much less try to create policy to address the problem).
Are We Sure This Is a Problem? Scientists Were Saying Different Things [X] Years Ago...
There were competing theories about why this subduction zone seemed so atypically quiet for a geologically active region; either the pressure was being released by some mechanism, or the fault was locked and building-up pressure for abnormally long periods of time. As science does, there were debates over the competing theories and (much warranted) skepticism over the most alarming possible scenario. Researchers from the USGS & the Japanese equivalent (I apologize but I cannot for the life of me find the translated name of the organization) surveyed the coast & dug into First Nations histories for evidence; they found entire red wood forests that had been violently plunged into salt water, stories & myths that corroborated the hypothesis of previous cataclysmic seismic activity and arrow grass blanketed by tsunami sediment. Tree ring dating from the red wood 'ghost forests' suggested that they had died around the year 1700~. Records of an 'orphan tsunami' striking Japan - a wave that did not, from their perspective, appear to be accompanied by an earthquake - were found, which further corroborated the data and also provided a precise date:
January 26, 1700, at about 9 o'clock in the morning.
All of the above was established around 1987. Since then, evidence has been uncovered of about 41 events in the last ten thousand years, 19 of them likely to have been full length ruptures of the fault line.
The Geological Survey of Canada's most recent study suggests that the fault line's most severe events have a recurrence interval, on average, of about once every 480 years. For events less severe than a full rupture (but nevertheless quite powerful), the recurrence interval averages out to about once every 240 years. We're about 316 years away from that last major rupture in January of 1700 - so we're coming close to being due for a real bad day.
So What Can We Even Do About This?
On a state level, we ought to be lobbying for some amount of budget allocation to both study & prepare for the earthquake that is going to be coming (unfortunately, earthquake forecasting is basically impossible; but more information on the phenomena never hurts). We need preparation plans that give respect to the danger being presented.
We also need a very large investment in upgrading homes, businesses, large free standing structures (towers & skyscapers, for example), which are not currently built to do anything other than crumble in the event of a quake.
On a personal level: make sure your home is anchored to it's foundation. If it isn't, see if there is any kind of program available in your area for retrofitting your home to get it anchored. Consider getting rid of shelving units that are large and free standing, or so if it is reasonable to secure them to the wall. Likewise, see if it is reasonable to get your large appliances secures to the wall or floor. Consider getting latches for cupboard doors and/or retention straps, to prevent everything from becoming shrapnel in the event of a quake.
Put together a reasonable, accessible & portable survival package. Some basic food that doesn't need cooking, a day or two worth of drinking water, a first aid kit, etc. Many people do just fine in the initial wake of the impact but find themselves trapped in their home or apartment with nothing to eat or drink until they're found - having a kit handy may prevent you from being among those folks.
If We Roll Snake Eyes On the Earthquake Dice Tomorrow, What Do I Do?
If you are outside, stay outside. If you are inside, stay inside. The most dangerous place to be is near an exterior wall of a house or building (...well, except maybe for being inside a skyscraper. Then you're pretty boned, sorry; just pray that it doesn't pancake).
If you are inside, you want to find what search & rescue teams have dubbed 'survivable void space' - get underneath a sturdy object (no, your Ikea night stand does not count) to use as a shelter against the ceiling coming down (and/or other heavy objects falling) and hold on. DO NOT STAND IN A GODDAMN DOORWAY! Doorways only work if the house has been built to withstand earthquake shocks, and if you live on the west coast, yours hasn't been
If you are outside, stay away from big heavy things that could fall on you and try to reach high ground.
If you live right on the coast, there's going to be a tsunami coming your way; after the shaking stops, do your damndest to get to high ground.
Don't try to be a hero in the heat of the moment; if you feel compelled, search & rescue will no doubt be looking for volunteers once the immediate danger has passed.