Disclaimer: this entire post is based on under 60 seconds of Google and Wikipedia

According to Wikipedia, the USGS does not use the Richter scale and hasn't since the 70s or so. They use the "moment magnitude scale" but since the numbers are still pretty close to the Richter scale, it is commonly (and incorrectly) called that: http://en.wikipedia.org/wiki/Moment_magnitude_scale

More info can be found in the first paragraph of http://en.wikipedia.org/wiki/Richter_magnitude_scale where they talk about why the Richter scale gets saturated at higher levels.

Earthquake yes, tsunami no. Tsunamis can't really get through narrow gaps; even a large wave would be dissipated by Admiralty Inlet. Victoria, Port Townsend, even Bellingham could get hammered, but the real action is always going to be on the open ocean coast.

I heard a UW guy on the radio the other day saying that it would be almost impossible for Seattle to get more than a few inches of surge.

Tsunamis here normally hit the coast and sometimes come through the Strait of Juan de Fuca where they can impact the north part of Whidbey Island, Bellingham, etc. For a tsunami to harm Seattle, the earthquake would have to take place directly beneath Puget Sound. In that case, Puget Sound acts like a bowl of water sloshing back and forth. This has happened.

My understanding is that it behaves like a liquid. See this handy wikipedia article: http://en.wikipedia.org/wiki/Soil_liquefaction

Most freaky is that it can happen to soil layers below the top layer, allowing them to "boil up."

This phenomenon is what terrorizes me about the SODO area of Seattle. During an earthquake, that mud/sandy fill becomes a big bowl of mudflat soup.

Roger Faris is one of the top experts in Seattle on preparation of homes for earthquake . He was a driving force in the implementation of the standard earthquake retrofit plan for the city of Seattle and taught the city's "How to Retrofit Your Own Home" class for several years. His dry wit keeps the subject interesting. If you missed this program, call and see if they will air it again.

Nova had a great episode called "Mystery of the Megavolcano" that covered this very well and still gives me nightmares. It used to be available to watch online, but now harder to find for free.

Planning and preparation are great ways to remove worry and stress and they don't require much time. Once a month, do one thing to be better prepared. Make it a family activity. "Prepare in a Year" offers a handy guide: http://www.emd.wa.gov/preparedness/documents/PE_PIY_Booklet.pdf

Keep in mind: We prepare for a lot of things in life... the birth of a child, job interviews, weddings, vacations... preparing for disasters is also a worthy investment of time.

I recommend having an emergency kit in your home, office/classroom, and vehicle. While these kits may include some different and unique supplies (e.g. flares and warm clothing for the car), each should contain water, non-perishable food, needed medications, basic first aid supplies, a whistle and small flashlight. Should an earthquake or other disaster strike, these handy kits can sustain you for a period of time until additional help is available. Visit www.3days3ways.org for checklists and other tips.

Fear phobia aside...

You're asking to put a price on life.

I'm not buying.

I think it can, especially if it's big enough. I think it's more likely to happen during flooding. And it can get big enough to take out a car, like the picture below, but probably not like Hollywood's 2012. That's fake.

No. I think one should look at what demographic they are and the associated risk factors for death/injury and be concerned about reducing your risk of dying from that.

Cardiovascular disease, alcohol and drugs, domestic violence and car accidents are typically the way most young people go out. And even this long list can be broken down into more like two big categories, most falling under substance abuse in some way.

Here's a list of death factors and you'll see war on the list, but not dying in an earthquake. So if you're in an demographic that can be drafted, be worried about that.

http://en.wikipedia.org/wiki/List_of_causes_of_death_by_rate

Most people who are prepared for earthquake are able to release the worrying and stressing once they have done what they know to do to be ready . We have no control over nature's forces. We can control what we do to prepare. Preparation is positive. For the unprepared, dealing with the aftermath of a tragic event is painful. There is no balance here. Preparation is by far the best path.

This is a really great question, I think. But it is a tough one to answer simply, in part because there are so many levels on which you've posed it (from time spent to psychological impact) and because there are so many uncertainties (for example, we don't know that event X is going to strike--is time spent preparing for it therefore wasted?).

My short answer is this, and it is my personal opinion: I think we should spend less time worrying and fretting about possible disasters and relatively more effort in rational and sensible preparations and precautions that would prevent natural threats from becoming disasters. Examples of sensible preparations and precaustions we can do about the earthquake threat include: 1) education, 2) threat monitoring, 3) developing and enforcing the most well-informed design and building codes, 4) encouraging and rewarding simple mitigation measures, and 5) having personal and family emergency plans and kits [but not going overboard on these].

For earthquakes--the only thing I can claim to know anything usefully quantitative about--one way to look at your question is to reduce it to a money question [dollars and "sense"?]. FEMA (the Federal Emergency Management Agency) has produced a valuable report, updated in 2008. In it they estimate that based on the best current thinking, earthquakes will cost annualized losses (AEL) within the state of Washington of $366,431,000. That is what the cost each year of the impacts of expected earthquakes affecting the state will be, averaged over time. The question becomes, what fraction of that should be spent to prepare for, and mitigate, those potential losses? Can we substantially lower this amount by spending relatively little? Or should we just shrug our shoulders and acknowledge that somebody will have to pay these costs eventually? [By the way, the report has other information of interest, like number of expected displaced households, and tons of debris expected to have to move, etc.]

Another thing that makes this tough is that when a natural threat takes place--and you've prepared, it is difficult to be sure how much you've saved. How much worse would it have been had you not spent the effort? I think the disaster in Haiti demonstrates a worst-case scenario that has nothing to do with our circumstances. But it does illustrate what happens when society is absolutely unprepared.

One final point is that we tend to focus on the Katrinas and Haitis and Sumatras that really blast a region and its inhabitants. Far more likely for earthquakes in Washington, and arguably what we should spend the most effort on, are scenarios where there are pockets of damage (as opposed to regional devastation) that may have significant economic impacts regionally. I imagine the port facilities being damaged such that industries can't ship materials easily, as one potential example. Or transportation corridors being disrupted so that business can't move materials around. We must acknowledge that we're going to get knocked down. We should be prepared to pick ourselves up, dust ourselves off, and get back to life--which should NOT be spent worrying about potential disasters!

Disasters in general are worth preparing for.

Here's my case study: I know a guy named Bob. Nice guy. Used to be a fire chief in Sioux City, IA, but he's retired now. He worked for the city starting in the '80s. Every year, the city would do a disaster preparedness drill, and every year, some idiot on the city council would claim that they spent too much money on the drills and that nothing ever happened there anyway.

And then this happened.

Bob told me that that crash was the worst call he'd ever been on, but that the only thing that kept everyone from dying were those preparedness drills had been ongoing and the people on the grond had practiced. Ever since, the city does its drills and should anyone complain about the cost, that crash gets brought up and the complaints die.

From personal experience, flooding really sucks. My husband and I weren't as prepared as we could have been, and as a result, we lost a lot of stuff that could have been saved. Consider: are a few minutes of preparation worth potentially losing thousands of dollars in the event of a disaster? Insurance doesn't cover everything.

The caveat is that if one is paralyzed by fear of disasters, then you need help.

I think it depends on which part you spend most time on. Worry and stressing is non-productive, true. But the time spent to prepare for a natural disaster could save my life or make the aftermath of the natural disaster a hell of a lot less uncomfortable.

Case in point: I used to live in hurricane country. Worrying about hurricanes=useless. Installing storm shutters=very good idea that avoided blown-out windows during one hurricane.

Judging from the beacon hill LINK tunnel and the geology lessons (unaccounted sand pockets turning into frontyard sinkholes) there about our local ground...
yes there's danger
...IF you live above a LINK tunnel. =)

There is a great video about this, entitled "Cascadia - the Hidden Fire." It aired on PBS. It interviews a number of northwest seismologists, describes the great Alaskan earthquake of 1964, and underlines the risk Seattle faces. It is available at: http://www.equakevideo.com/

The Yellowstone Caldra. I first read about it in a wonderful, lighthearted, book by the title of, "A Short History of Nearly Everything," by Bill Bryson. I could not sleep for a week after reading his description! However, National Geographic did a feature on it in 2007. The caldra is there, but their conclusion was much more pedestrian! Check it out at: http://news.nationalgeographic.com/news/2007/11/071108-yellowstone.html

It is not necessary to have water and a whistle in every room, but it is a good idea to have a stash of emergency supplies which contain water and a whistle.

In Seattle and most of the United States, buildings are mostly constructed of wood. Our homes are elaborate wooden boxes, for the most part. Our grander apartment and condo buildings are elaborate steel boxes. As a result, even if the house or apartment building fails, it will retain its box-like shape. That means we will probably not be crushed by the building itself. If we drop, cover, and hold while everything is shaking, we will likely be able to get up and go get our water and whistle after the earthquake shaking stops.

What will crush us is the big screen TV, if it is not restrained. Or our tall bookcases, if they are not anchored to the wall. Or that big mirror, or those large framed pictures above the sofa, or perhaps that prize Chihuly glass sculpture proudly displayed on the mantle of the fireplace....maybe we should place it on the hearth. You get the idea. The rule of thumb is, if our possessions can rattle around and hurt us, or if they are valuable and may be hurt in the severe shaking of an earthquake, we should take the effort to secure them.

You can look at some illustrations of the basics of securing things in your home at http://www.emd.wa.gov/preparedness/prep_home.shtml. Or check out the home hazard hunt at https://eqhomesafety.websitesource.net/earthquakehazardhunt.html.

Oh, and about that whistle. Be sure to store your emergency supply pack near the exit. It needs to be handy to pick up if you are getting out in a hurry.

Oh, great. Something else for me to have nightmares about.

NO. It'll kill those who can't escape to the east coast.

During an earthquake we observe several different sorts of ground failures.

Let's imagine the earthquake process in a couple of stages, First, driven by stressed rock, a fault plane ruptures (i.e., one side moves relative to the other). This release of elastic energy -- like a stretched rubber band, but rather stored in the stretched rocks around the fault, radiates outward as seismic waves in all directions. These seismic waves cruise outward through the rock and, near Earth's surface, interact with lots of just normal rocks and soils. But there are also pockets of soft weak soil, wet sandy muck (another technical term!), cliffs, and other topographic features. Seismic waves can cause failures in these weak features, too.

So:

Ground failure #1 is where a fault rupture itself intersects Earth's surface. Different types of faults lead to different detailed patterns in the faulting. But since the dominant motion of a fault rupture is shear -- the sides slide along against each other -- fault breaks aren't likely to swallow anybody up! This just doesn't happen.

Ground failure #2 is related to liquefaction--where a wet sandy soil is shaken so violently that it looses cohesion and compacts--often squirting water and sand out onto the surface--and looses it's bearing capacity; buildings may list, or even fall over. If there is the slightest slope, liquefied soils will flow, and may break up into blocks. The wonderful picture of the Turnagain Heights liquefaction features in Anchorage that O my captain attached to his answer is a beautiful example of this type of ground failure.

Ground failure #3 is triggered landslides. This one's easy, you shake a hillside and gravity tumbles it down. This can bury folks, like any landslide. However nothing opens up and swallows you.

Yes I've spent a professional lifetime telling people not to worry, the ground WILL NOT open up and swallow you and then close again. THEN I took this picture after the ChiChi earthquake in Taiwan, 1999. My team and I couldn't figure out how---but this is the only thing I've ever seen that made believe it was possible....(!)

Unfortunately, e-mails have been circulating on the Internet incorrectly touting the "Triangle of Life" technique which allegedly use voids as a way to survive earthquakes. Simply put, the technique is not applicable for earthquake experiences in the United States.

The "Triangle of Life" is not appropriate for use in the United States because the research used to illustrate the method were based on earthquake response and recovery in Turkey, a country very different from the United States when it comes to building standards, construction and engineering techniques, and building codes.

Earthquakes in the United States do not typically result in total building collapse or "pancake." As a result, when earthquakes strike in the U.S., the safest thing for children and adults to do is "Drop, Cover and Hold" underneath a desk, table, or other sturdy strong surface.

The "Triangle of Life" also advocates for getting out of bed if caught asleep during an earthquake. Again, this is incorrect for the United States where the bed could provide more safety during an earthquake because rolling onto the floor beside it, where you could be injured by debris. The more you move during an earthquake, the more potential there is for injury.

The best method for earthquake safety in the U.S. is "Drop, Cover and Hold". If you have received an email about the "triangle of life" please respond to its sender by directing them to www.earthquakecountry.info/dropcoverholdon/ and ask them to forward this link to others they may have contacted.

"Drop, Cover and Hold" is still the best method for earthquake safety, and is endorsed by the American Red Cross, FEMA and the U.S. Geological Survey.

Your past experience in earthquakes may give you a false sense of safety. In some cases you may not have done anything, or you ran outside, and survived with no injuries. Or perhaps you got under your desk and others thought you overreacted.

However, you likely have not experienced the kind of strong earthquake shaking that is possible very large earthquakes: sudden and intense back and forth motions of several feet per second will cause the floor or the ground to jerk sideways out from under you, and every unsecured object around you could topple, fall, or become airborne, potentially causing serious injury. This is why you must learn to immediately protect yourself after the first jolt... don't wait to see if the earthquake shaking will be strong!

In MOST situations, you will reduce your chance of injury if you:

DROP down onto your hands and knees (before the earthquakes knocks you down). This position protects you from falling but allows you to still move if necessary.

COVER your head and neck (and your entire body if possible) under a sturdy table or desk. If there is no shelter nearby, only then should you get down near an interior wall (or next to low-lying furniture that won't fall on you), and cover your head and neck with your arms and hands.

HOLD ON to your shelter (or to your head and neck) until the shaking stops. Be prepared to move with your shelter if the shaking shifts it around.

While images of collapsed structures in earthquakes around the world are frightening and get the most attention from the media, most buildings in the U.S. do not collapse at all, and few completely collapse. Strict building codes have worked to greatly reduce the potential of structure collapse.

However, there is the possibility of structural failure in certain building types, especially unreinforced masonry (brick buildings), and in certain structures constructed before the latest building codes. Rescue professionals are trained to understand how these structures collapse in order to identify potential locations of survivors within "survivable void spaces."

The main goal of "Drop, Cover, and Hold On" is to protect you from falling and flying debris and other nonstructural hazards, and to increase the chance of your ending up in a survivable void space if the building actually collapses.

While a doorway may be an alternate "safe spot" option if you live in old, unreinforced or older woodframe houses, you may not be able to brace yourself in the door during strong shaking. In modern houses, doorways are no stronger than any other part of the house, and the doorway does not protect you from the most likely source of injury- falling or flying objects. You are safer under a sturdy table.

Check out this link for additional tips for surviving an earthquake in a number of different locations and situations: http://www.earthquakecountry.info/roots/step5.html

If you are clear-headed enough when you feel a strong earthquake to think "Hmmm. Let's see  ... now, do I stand in a doorway? Or ... maybe get under my desk? Or, no! I should run outside!" then you are a real cool customer and will have no problem surviving anything that happens.

The couple of truly large earthquakes I've been in have taught me that my body (and the Earth) will do what they want, and I'm just a passive observer: "Oh my, I'm trying to get out of bed and I keep getting heaved back onto it!" or "Wow! Here I am out of doors..isn't that supposed to be a dumb place to be? How did I get here?". So I'm not the cool analytical sort during an earthquake, apparently.

If you happen to be, then here's my prejudiced opinion for you to consider when the next large earrthquake strikes. I think it matters greatly where you are. If you are in a well-constructed office with sturdy furniture, then "Drop, Cover, and Hold" may be for you--protects you from projectile-books and falling ceiling tiles. If you are in an mud-chinked river-rock cabin with turf on the ceiling, then you best get outside ASAP, jumping underneath that flimsy card table isn't going to protect you from the tons of primitive building materials about to come your way. If you have no furniture to jump under and have a nice arched doorway with no door in it and far away from that big picture window in your living room...why then probably you should saunter over there and brace yourself in it. There are some advice videos  from SCEC (the Southern California Earthquake Consortium) available online by clicking here .

There are some places I simply feel out of place being in. A parking structure in the city is one, the Alaskan Way Viaduct another, any elevator too. It is my plan not to be in one of those when the earthquake hits. Maybe someone else has good advice for these spots, if you can't avoid them.