One of the benefits of our rapidly-increasing knowledge of the planet is that we're coming to better and better understand seismic activity: we may not yet be able to predict quakes (though we're getting close), but our insight is getting sharp enough to understand them incredibly well. Case in point? This very cool site which details in fairly high resolution the shaking patterns of the 1906 quake that destroyed San Francisco. It's full of interesting information -- check out, for example, these simulations of how that quake would affect some famous structures today.

(via BB)