Italian seismic amplification factors for peak ground acceleration and peak ground velocity

Ground motion modification over large areas is generally evaluated by focusing on source effects disregarding local lithostratigraphic site conditions. Hence, amplification maps of peak ground acceleration and peak ground velocity are proposed to improve the forecast of ground motion on a national scale. Topological information about litho-type successions and soil mechanical behaviour were retrieved from the Italian database of seismic microzonation and more than 30 million of seismic site response analyses were performed to quantify the amplification factors (i.e. the ratio between expected ground motion at the site of interest and that at the outcropping engineering bedrock). The maximum value of the amplified peak ground acceleration on the Italian territory results in about twice as much as the value expected at the outcropping of the engineering bedrock. Finally, damage scenario maps based on the amplified ground motion could be produced as a supporting tool for urban planning and emergency system management.

大尺度区域的地震动修正研究通常仅聚焦于震源效应，而忽略了局地岩石地层场地条件的影响。为此，本研究提出峰值地面加速度（Peak Ground Acceleration, PGA）与峰值地面速度（Peak Ground Velocity, PGV）的放大因子分布图，以提升国家级尺度下的地震动预测精度。研究人员从意大利地震微区划（Seismic Microzonation）数据库中获取了岩性层序拓扑信息与土体力学特性数据，并开展了超3000万次地震场地响应分析，以量化放大因子——即目标场地预期地震动与出露工程基岩处地震动的比值。意大利境内经放大后的峰值地面加速度最大值，约为工程基岩出露处预期地震动值的两倍。最终，基于放大后地震动的灾害场景分布图可作为城市规划与应急系统管理的辅助工具予以编制。