Smarter emergency managers that I know are keeping track of the inventory of unreinforced masonry (URM) buildings in their areas, because in a local quake those will be the first to go down, and go down hard. And there are handy maps of our liquefaction prone areas, they are well known. The ChCh quake was shallow and lasted for ~45 seconds, an eternity for anyone there. When Seattle has its EQ, it will last upwards of 4 minutes. Liquefaction areas - much of downtown Seattle, some northern neighborhoods, the entire industrial area and harbor area of Harbor Island - will be turned to jello, impassable. Building codes are like opinions, everyone has them - and little of the built environment is built to the most recent code, usually it has been retrofitted to an earlier code. And even those codes were built for outdated EQ scenarios, such as 45 second temblors rather than 4 minute shakes.

People are funny this way - if the magnitude of an EQ event is too scary or too catastropic to deal with by a sane building code, they will actively work to define the problem in a way that they can deal with and mitigate. This is going on right now - Seattle wants to build the largest tunnel in the world (?) to replace the Alaskan Way Viaduct, which runs along the waterfront behind a seawall (which is also failing and in need of repair). Now, there's no doubt that the Viaduct needs to be replaced, the problem is that city fathers and planners have grand plans for the space that would be opened up by an underground tunnel; the real problem with a tunnel is it will be forced through an area extremely prone to liquefaction. Tunnel collapse, inundation with seawater, even tsunami are some of the risks. So they are going great lengths to re-define the threat scenario, including choosing a EQ that is not the most damaging possible, nor are they choosing the most likely shake scenario, which will go on for minutes, not seconds. And of course, not answer in a definitive way, what if Puget Sound experiences a tsunami? The curt answer is, if a tsunami hits we have other crises to deal with. Which begs the question, why a tunnel, when an above ground throughway can be constructed to replace the Viaduct, at much lower cost, and built to survive tsumanis and EQ damage. That's an inconvenient question, as long as so many have so much money invested in all the new found waterfront that building a tunnel could open up. In the end, you can ask the question, will the new tunnel survive? The answer is Yes, to the question asked for a ChCh style quake: if you ask the harder question, could this tunnel survive a 4 minute shallows Seattle Fault quake, the answer gets much sketchier.

Apparently the Seattle city fathers have decided in favor of drilling their tunnel, and when The Worst Happens someone else will have to deal with that. The law of averages says it won't be them anyway. I would be happy if they started by asking the right questions, and if they still came to this answer, then so be it. Never underestimate the power of denial...