Active Fault Near-Source Zones within and Bordering the State of California for the 1997 Uniform Building Code

The fault sources in the Project 97 probabilistic seismic hazard maps for the state of California were used to construct maps for defining near-source seismic coefficients, N_a and N_v, incorporated in the 1997 Uniform Building Code (ICBO 1997). The near-source factors are based on the distance from a known active fault that is classified as either Type A or Type B. To determine the near-source factor, four pieces of geologic information are required: (1) recognizing a fault and determining whether or not the fault has been active during the Holocene, (2) identifying the location of the fault at or beneath the ground surface, (3) estimating the slip rate of the fault, and (4) estimating the maximum earthquake magnitude for each fault segment. This paper describes the information used to produce the fault classifications and distances.