Prediction of surface ground motion based on advanced approaches is a non-trivial task at large area. In fact, advanced approaches require a detailed geological and geotechnical subsoil model based on geological, physical and mechanical properties retrieved from in situ investigations and laboratory data, and to perform time consuming numerical simulation of the seismic site response. Bearing in mind that there is a lack of available site investigations and laboratory data at large area, simplified methods based on “soft data” are often adopted. On this regard, a methodology to perform seismic site response analyses at national scale is proposed in this paper, based on the following assumptions: 1) homogeneous areas were identified at national scale based both on morpho-geological and lithological properties, in order to classify and analyse site-data archived in the Italian database of seismic microzonation studies; 2) geotechnical subsoil one-dimensional models of the Italian site conditions were defined according to site-data; 3) in accordance with the reference seismic hazard levels, pseudo-acceleration response spectra were selected as input motions for numerical simulations.

About thirty million numerical simulations of seismic site response were performed, and national maps of seismic shaking amplification factors were produced in terms of ratio of response spectra referred to three intervals of period. This estimation of surface ground motion based on the proposed procedure is a supporting tool for large area territorial and emergency planning.

在大范围内，基于先进方法的地表地面运动预测是一项艰巨的任务。实际上，先进的方法需要基于从现场调查和实验室数据中获取的地质，物理和力学特性的详细的地质和岩土地下模型，并执行耗时的地震现场响应数值模拟。考虑到缺乏大范围的现场调查和实验室数据，通常采用基于“软数据”的简化方法。在这方面，本文提出了一种基于以下假设在全国范围内进行地震现场响应分析的方法：1）根据形态，地质和岩性，在全国范围内确定了均质区域，为了对意大利地震微区研究数据库中的现场数据进行分类和分析；2）根据现场数据确定了意大利现场条件的岩土地下一维模型；3）根据参考地震危险等级，选择了伪加速度响应谱作为数值模拟的输入运动。

进行了大约三千万次地震现场响应的数值模拟，并根据响应谱的比率（以三个周期为间隔）绘制了地震震荡放大因子的国家图。基于提议的程序进行的地面地面运动的估计是大面积领土和应急计划的支持工具。