Correlation between Ground Motion Based Shaking Intensity Estimates and Actual Building Damage

Inspection records from 104,025 buildings surveyed in the aftermath of the 17 January 1994 Northridge, California earthquake (Mw=6.7) along with publicly available ground motion data from that earthquake are used to investigate correlation between ground motion intensity and damage levels, and to find reliable building damage indicators. Damage is represented using three damage levels as prescribed by the inspectors. Each structure is associated with the ground motion parameters obtained from the closest ground motion recording station or the closest geographic grid point provided by the United States Geological Survey (USGS). As the nature of the dependent (damage levels) and some of the independent variables are ordered and integer-valued, besides the regular statistical correlation analysis a random parameter ordered probit statistical model is considered in the study. A critical evaluation of parameters that have strong influence on building damage is provided. The impact of distance to ground motion recording station on observed correlations is also presented.