The hazard from liquefaction is not nearly as great as from shaking. Rather, liquefaction is of concern because it focuses its effects on infrastructure, particularly infrastructure that is critical for emergency response. For example, a home may be no more likely to be uninhabitable following the Loma Prieta earthquake in an area mapped as very high liquefaction susceptibility than one outside of such an area, given equivalent shaking intensities. However, those buildings damaged may have foundation damage that is potentially more expensive to repair than shaking-caused structural damage. While shaking does most of the damage to highway structures, liquefaction is responsible for extensive damage to airports (particularly runways), harbor facilities, and road and highway surfaces. In addition, areas with high liquefaction susceptibility had more damage to underground water, sewer and natural gas pipelines in the Loma Prieta earthquake than areas with lower liquefaction susceptibility, given equivalent shaking intensities.

The following pages provide data on the impacts to various parts of our built environment, including:

utility pipelines;
highways, roads, and airport runways;
harbor facilities; and
buildings and other structures.

These pages contain summaries of the extent of liquefaction damage in the Loma Prieta earthquake, why damage happens, and existing programs of various utilities and government agencies to mitigate this hazard.