“The Full-Rip Nine”
Thanks to Carol Dunn and King 5 News, I spent the morning reading this remarkable article by Bruce Barcott on the potential for a massive earthquake in the Cascadia subduction zone. He outlines, in dramatic fashion, potential effects from a 9.0 quake that runs up and down the coast of the Pacific Northwest. (You can learn more about these risks, in a more visual medium, from the excellent documentary Cascadia: The Hidden Fire).
Since the Depiction offices are located right in the midst of the region, this is obviously fairly important to us here, both personally and professionally. And as Carol pointed out on Twitter, “Reading is a good start, but action is the way to reduce harm.”
FEMA has some excellent advice on that score here. You should also build a disaster plan–and Depiction is a particularly good tool for doing that visually.
One of the hazards Barcott mentions is “liquefaction”:
In Seattle and Portland, the strong shaking begins to induce liquefaction, a process in which the sandy soil that portions of both cities are built on turns into a thick, slurry-like liquid. Parts of Portland rest atop sediment laid down by the Willamette River, and Seattle’s waterfront sits on tidal flats overtopped by loose fill. In a quake, this unconsolidated fill loses its ability to support heavy structures.
The downtown areas aren’t the only places at risk from liquefaction, though. I put together a depiction that includes liquefaction risk for much of the Puget sound region (7.15 mb). There are many large areas, but also pockets of risk scattered all across the region. (This isn’t the only hazard you should be watching for–see Barcott’s discussion of unreinforced-masonry buildings as well–but it’s a place to start.) If you don’t have Depiction, you can explore the above file with the Depiction free reader.
If you do have Depiction, the Washington state liquefaction data I used in the depiction is available here in shapefile format (54.8 mb)(just unzip it all into a folder and add the .SHP file to your depiction). Oregon doesn’t have that information quite as readily available, but they do have a predicted tsunami inundation line (13.4 mb)
The UN’s Global Risk Data Platform also has useful information, some of which is included in the above depiction. You can access it by putting this link into the Web services pane (select WMS, then click “Show content”).