Last summer, a startling article appeared in The New Yorker magazine outlining what could happen to the Pacific Northwest in the event of a large earthquake resulting from a full rupture of the Cascadia Subduction Zone. As recently as 1700, this convergent zone produced an earthquake estimated at magnitude 9. The article attracted a great deal of attention, especially among people who had never heard of the possibility that the heavily populated Pacific Northwest could, in a geologic moment, become “toast” — as someone quoted in the article put it. The San Francisco Bay Area also suffers from the unfortunate...