Ground Acceleration near St. Michael's Church during the 1886 Charleston, SC, Earthquake

The historic and continuing seismicity in the southeastern U.S. indicate the seismic threat to the population. However, little is known about the engineering characteristics of eastern U.S. earthquakes because there are no strong motion recordings of them. In particular, the peak ground acceleration, needed for structural design, is not available except through correlations with western U.S. earthquakes or MMI data of unknown uncertainty. This paper estimates the peak ground acceleration experienced by St. Michael's Church during the 1886 Charleston, SC, event based on conventional and probabilistic structural analysis. The 1886 event, rated as MMI X and magnitude 7, is the only historic strong motion event greater than m_b = 5 that affected Charleston. The analysis concluded that the peak ground acceleration for the 1886 event was 0.33g. The coefficient of variation of this acceleration was 24%, remarkably small when considering the uncertainty in the input parameters.