Earthquake Environment for Physical Design: A Statistical Analysis

A statistical analysis of nationwide seismic activities is made to determine the level and characteristics of earthquake motions to be expected in different geographical locations. Such information is needed to identify the severity of the earthquake threat to telephone facilities and to specify adequate design requirements. This paper describes the essential seismic environment including the expected earthquake-magnitude levels and the corresponding frequency of occurrence for different seismic-risk zones, and the free-field and in-building motions that might be induced by earthquakes. Stochastic models are used to analyze the earthquake-occurrence statistics, and to describe the induced random ground motions. Historical earthquake data are used to verify the theory and to generate information useful for seismic design.