A visitor to Bucharest, Romania’s capital, will notice that many of the city’s buildings—which range from graceful Belle Époque mansions constructed in the late nineteenth century to unlovely apartment complexes thrown up during postwar urbanization—are marked with a bright-red disk. Unlike the blue plaques affixed to residences in London, which indicate where notable figures once lived, or the Stolpersteine (or stumbling stones) embedded in the sidewalks of German cities to mark the former homes of Holocaust victims, Bucharest’s red disks are not commemorative but predictive. “It means that, in the next earthquake, this building could fall down,” Radu Jude, the...