In this video footage, dusk descends on the city as the Marina district fires begin to spread and residents pull together to fight the flames and shore up collapsed buildings. In this experiment with soil liquefaction , you'll see what happens when filled land experiences an earthquake. The Marina district of San Francisco, and some of the elevated freeways near the bay, are built on landfill built over former marshlands. When surface waves from the Loma Prieta earthquake hit that sandy, water-logged soil, the vibrations created an unstable soup, a phenomenon known as liquefaction. Liquefied soils aren't good at supporting heavy concrete roads or buildings.
Buildings made of bricks without a solid wood or steel frame are especially vulnerable.
All over the Bay Area, especially areas with loose, soggy soils, URM buildings tumbled to the ground under powerful surface waves from the earthquake. It's especially ironic that the Loma Prieta quake hit the Marina District so hard, since the entire area was built on the landfill made from the ruins of the 1906 quake. Afterward, the Marina District went through a housing boom, setting up the opportunity for history to repeat itself. The Exploratorium, which had gone through some earthquake retrofitting, survived Loma Prieta, but dozens of other buildings in the Marina District did not.