A COMPREHENSIVE SEISMIC VULNERABILITY AND LOSS EVALUATION OF THE STATE OF SOUTH CAROLINA USING HAZUS: PART Ⅱ GROUND MOTION HAZARD

摘要

As part of a comprehensive statewide seismic risk assessment of South Carolina, ground motions were estimated for four scenario earthquakes using the finite-fault and point-source versions of the stochastic numerical modeling approach. The scenarios included a moment magnitude (M) 7.3 "1886 Charleston-like" earthquake, M 6.3 and M 5.3 Charleston events, and a M 5.0 earthquake in Columbia. Statewide maps for surficial ground shaking in terms of peak horizontal acceleration and velocity and 0.3 and 1.0 sec spectral acceleration were produced for each scenario by multiplying the stochastic model-computed rock motions by soil amplification factors. These factors were calculated as a function of site response category, spectral frequency, soil thickness, and input rock motion. A geologic and geotechnical characterization of the State was used to define five site response categories. In the calculation of the scenario ground motions for the M 7.3 Charleston earthquake, the finite fault parameters were varied because of the considerable uncertainty regarding the source of the 1886 earthquake. These parameters were weighted to obtain the best simulation of the observed patterns of ground shaking and liquefaction in 1886. The greatest weight was given to a 100-km-long, north-northeast-trending, strike-slip fault coincident with the Woodstock fault. The resulting calculated peak horizontal accelerations for the M 7.3 scenario event were as high as 0.6 to 0.7 g on soil in the vicinity of the modeled rupture near Charleston. For the M 6.3 and 5.3 Charleston scenarios, the highest peak horizontal accelerations are estimated to be > 0.3 g and > 0.2 g, respectively. A M 5.0 earthquake in Columbia could result in peak values greater than 0.2 g.