How did the 1906 San Fransisco earthquake make the damage caused by the 1989 San Fransisco earthquake worse?
I put in some time writing this. If all you want is the direct statement — “unconsolidated sediments led to liquefaction” — then I guess I wasted my time. I hope not. San Francisco is pretty complicated, geologically. There are certain areas of almost blatantly exposed solid bedrock, and other areas of completely unconsolidated sediments. Back in the old days, most people didn’t pay much attention to their foundation rock, not really even paying attention when things started to lean. Many of the buildings in the city were made of wood structure and wood facade. Only the inner city, the financial district and government buildings, had any real brick or stone facing. You build something on bedrock, you’re in “pretty good shape.” But when you build something on unconsolidated sediments, you’re putting yourself up s_-t creek, because when seismic waves hit them, they can cause an effect known as “liquefaction” where the sediments actually become basically a very loose fluid. Obviously, i
