大距离宽频带的地震动衰减关系是强地面运动研究的重要内容，例如NGA-East项目正在发展0-1000公里、频率范围在0.1-100Hz的广震中距、宽频谱的地面运动衰减方程，为北美中东部地震工程研究及应用提供可靠模型。在我国东部地壳厚度30公里左右的地区，在震中距100km 附近，Moho 界面反射震相SmS 发生了超临界反射，在高频段往往是最强的震相，影响着此范围的地震动衰减关系。地壳速度结构复杂地区SmS 的强度变化比较复杂，一维速度结构模型难以解释部分观测数据，需考虑Moho 界面起伏及地壳内部结构小尺度不均匀性的影响。本项目计划采用有限差分等数值模拟方法模拟Moho界面存在起伏、中下地壳介质速度存在不同尺度不均匀性情形下的高频(1Hz以上)SmS传播过程，分析临界震中距范围内高频地震动衰减关系，为广震中距、宽频谱的强地面运动研究提供参考。

Large distance and broadband ground motion attenuation relationships play a key role in ground motion prediction, e.g. NGA-East plans now are developing ground motion attenuation models up to 1,000km in the frequency 0.1-100Hz, aiming to provide reliable results for earthquake egineering applications in Central and Eastern North-American(CENA) region.Yet at the epicentral distance of about 100km postcritical reflection from Moho SmS phase tends to show the largest amplitude in eastern China regions with Moho depth about 30km. The amplitude of SmS shows considerable variations in the regions where crustal velocity structures are very complicated. Difficulties in explaining the observed data with 1-D velocity models make it is necessary to take Moho topography and small-scale heterogeneities in the crust into account. Here we intend to investigate the effect of uplift of Moho discontinuity and heterogeneity in the crust on high-frequency(>1.0Hz) SmS with numerical simulations. Moreover we also analyze the ground motion attenuation relationships, which can be referenced in strong ground motion prediction.