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Abstract:
With the increasing exploitation and engineering construction in the South China Sea, the seismic design problems of marine engineering are becoming more and more important. The east part of the South China Sea is located in the joint section of the continental plate and the oceanic plate, which belongs to the subduction zone with high seismicity and relatively large earthquake magnitude. Thus potential earthquakes may have significant effects on the engineering construction and development of the South China Sea. In order to investigate the characteristics of subduction earthquake ground motion and its attenuation rules, based on the real data of ground motion and numerical modeling results, the ground motions of interface and intraslab earthquakes are investigated. Results indicate that there exists regional differences of subduction earthquake ground motions. The ground motion of interface earthquakes attenuates slower than shallow crustal earthquakes. While the ground motion of intraslab earthquakes attenuates faster than that of the shallow crustal earthquakes. The modeling results of horizontal seafloor ground motion shows almost no impact by the sea water, but the amplitude of vertical component decreases with increasing sea water depth. Then an attenuation relationship derived from a hybrid method based on ground motion modeling and empirical relationship is developed. This may provide a reference for the seismic zonation and engineering construction in the South China Sea.
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