A COMPREHENSIVE SEISMIC VULNERABILITY AND LOSS EVALUATION OF THE STATE OF SOUTH CAROLINA USING HAZUS PART Ⅲ: LIQUEFACTION HAZARD

摘要

The liquefaction hazard in South Carolina was evaluated as part of a statewide comprehensive seismic vulnerability and loss evaluation using HAZUS. HAZUS considers the potential for liquefaction (in terms of liquefaction-induced settlement and lateral flow) in assigning the potential for building damage. In the initial step in assigning liquefaction demand (in terms of cyclic stress ratio), reference rock datum motions were calculated for four earthquake scenarios. The events were a moment magnitude (M) 7.3 "1886 Charleston"-like earthquake, M 6.3 and M 5.3 events also from the Charleston seismic source, and a M 5.0 earthquake in Columbia. For each earthquake scenario and characteristic geologic profile, an average cyclic stress ratio within potentially liquefiable soil was calculated across the state at a 5 km x 5 km grid pattern. The characteristic profiles were developed using available subsurface and shear-wave velocity information, and considered a wide range of soil and rock conditions. The liquefaction resistance of soil in the representative profiles was determined based on shear-wave velocity and the clay/silt content of the soil. The results of the characterization and analyses indicate that greater amplification and liquefaction demand are experienced in the Charleston region than in other regions of South Carolina. The greater liquefaction demand, as well as the common presence of loose sand deposits, results in a greater risk of liquefaction in the Charleston region.