Development of Expectancy Maps and Risk Analysis

Seismic zoning maps previously used in building codes in the United State have not considered the frequency of exposure to earthquakes in different regions. By combining available data on tectonics, regional geology, and seismicity new maps of the contiguous United States have been drawn based on the assumption of uniform risk exposure. Maps are presented for two quantities, effective peak acceleration (EPA) and effective peak velocity-related acceleration (EPV). These two quantities are then taken from the maps to obtain the lateral design force coefficients to be for the design of earthquake resistant structures. The development of these maps is the first portion of a major review of seismic design procedures.