shudder

Interesting picture from PBS's Center of the World. It shows the expansion of Manhattan's landmass. It's quite significant. I presume this is all landfill. Now when I lived in San Francisco I recall the landfill areas (e.g., the Marina) were hit the hardest. Landfill tends to liquify under significant shear stress. It's the opposite effect of some liquids with dissolved particles in them (like cornstarch). They behave like a liquid normally and a solid if you were to slap the top of the liquid hard (no splatter). Landfill turns into sludge with the shear stresses created by earthquakes and make for bad building foundations indeed. Few people know this but New York is an earthquake prone region. Prone is probably too strong of a word. They hit infrequently and without much force. But they do hit. Most notably in 1884 and 1737. Both quakes were in the region of 5.0 on the Richter scale.