中国西部地区新一代地震动衰减模型

New Generation Ground Motion Attenuation Model for Western China

针对我国西部地区,选取汶川地震和部分国外地震记录,通过残差分析方法建立考虑断层破裂机制、场地条件以及上盘效应的地震动衰减模型,应用随机效应回归方法确定模型系数.结果分析表明:模型整体上能较好地预测汶川Ms8.0级地震断层距200,km以内的地面运动,但在反应谱长周期段,模型预测值比实际观测值略大;模型在短周期段(T<1,s)预测反应谱与4个美国下一代地震动衰减关系(NGA)模型平均值一致,长周期段(T>2,s)模型预测反应谱小于美国下一代衰减关系模型平均值.

Based on the records from Wenchuan earthquakes and selected world-wide earthquakes, a new ground motion attenuation model considering the effect of rupture mechanism of fault, site condition and hanging wall/footwall effect was developed for western China utilizing residual analysis method. The parameters were deter- mined by random effect regression. The analytical results show that the model predicted values for Wenchuan earth- quake Ms8.0 at the distance less than 200 km are highly consistent with the ground motions observed except for some slightly over-predicted values at long periods. Compared with the average predicted spectra of four next generation attenuation （NGA） models, the predicted spectra of our newly-developed model provide similar ground motions at short periods （T〈 1 s） but smaller ground motions at long periods （T〉2 s）.