It's easy to judge the Pompeiians for building a city on the foothills of a volcano, but are we really any smarter today? If you live along the San Andreas fault in San Francisco or Los Angeles, geologists are pretty confident you're going to experience a magnitude 8 (or larger) earthquake in the next 25 years—that's about the same size as the 1906 San Francisco quake that killed an estimated 3,000 people and destroyed nearly 30,000 buildings. Or if you're one of the 9.6 million residents of Jakarta, Indonesia, you might have noticed that parts of the ground are sinking by as much as ten inches a year, with about 40 percent of the city now below sea level.