What Buildings Fall the Slowest in an Earthquake?

Houses and Other Small Buildings

• Many buildings have been retrofitted so that they will not collapse or even crumble in the event of an earthquake in areas such as Southern California, where earthquakes occur frequently. However, buildings with original masonry or construction in other earthquake-prone states may lack shear paneling and plates and joists that are bolted to the foundation required to keep a building safe in an earthquake.

  Even older buildings don't usually completely collapse, but they will crumble more quickly than modern buildings. States on the western side of the United States, as well as Maine and states in the south central area of the country, are more prone to earthquakes.

Alternative Building Materials

• Unreinforced homes, such as adobe homes or old wooden frame homes, may crumble quickly due to structural differences from modern homes. More modern homes in earthquake-prone areas usually have a sill plate installed, or a wooden panel that is bolted to the foundation and the pony wall or the floor framing.

  The foundation is also protected by joists, or frames of parallel boards that run beneath the floor for added support. Adobe or original wood frames don't usually have this type of reinforcement, creating heavier floors and roofs that are more prone to collapse and cause severe damage.

Apartments and Condos

• Buildings often shake side to side, making apartments and condos a target for collapse. Since these buildings are built economically, with a second story over open air parking garages, they can be highly unstable. Damage can range from cracked stucco or paneling to a complete collapse of the condo onto the ground floor, crushing cars or anything else that may be under the living space.

  Structures such as "moment walls," or rectangular metal frames made to fit the garage opening, can keep the structure from collapsing, but these retrofits are often costly and owners do not want to spend the money.

Skyscrapers

• Surprisingly, skyscrapers can be some of the safest buildings in an earthquake, as long as the building is constructed properly. Smaller skyscrapers may have diagonal cross bracing, or steel beams set in an "X" pattern along each wall. Opposite walls may have shear walls and a shear core in the middle floor to create a stable yet flexible structure. Skyscrapers that are constructed with a deep foundation and base isolators, or a layer of metal and flexible rubber between the foundation and the building, are more likely to remain standing after an earthquake.