Published maps will only provide generalized, uninterpreted information about specific areas. Every property consists of a unique combination of geologic and structural factors that must be considered to determine what might happen to a house during an earthquake. Therefore, an individual site study is necessary. Geologic factors include: type of underlying material, depth to bedrock, depth of groundwater, and slope of land. Structural factors include: materials used (wood or masonry) in construction, number of floors, design, and retrofitting present.
As a publicly-funded organization, the U.S. Geological Survey conducts regional hazard assessments in conjunction with State and local agencies. We provide information that is used by planning officials to mitigate hazards. The USGS does not undertake assessments of individual private property. Site studies must be arranged by the owner of the property with geologists or engineers in private practice. To locate a qualified professional, contact your State government to determine its certification or licensing requirements for professional geologists and engineers in private practice. State boards of registration maintain lists of individuals who meet requirements established in their State. A local real estate company may also be able to recommend a qualified professional.