Abstract Evaluation of bedrock stiffness and thickness effect on ground motion modification represent a key-issue in the perspective of seismic risk reduction policy, since the maximum depth of site prospection generally does not extend down to the stiff bedrock location. Site conditions were identified from the Italian database of seismic microzonation studies. Simplified and realistic numerical models were adopted, i.e. extended down to the soft and stiff bedrock, respectively, in order to perform seismic site response analyses. Results indicate that simplified numerical model provides a quantification of the surface ground motion modification with an error generally equal to ±10% with respect to the realistic model. Hence, the evaluation of seismic performance of sites based on simplified numerical models represents a support tool for seismic risk management at large area.

中文翻译：

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基岩刚度和厚度对地震现场响应数值模拟的影响。意大利案例研究

摘要 评估基岩刚度和厚度对地震动修正的影响是降低地震风险政策的一个关键问题，因为场地勘探的最大深度通常不会向下延伸到刚性基岩位置。场地条件是从意大利地震微带研究数据库中确定的。采用了简化和现实的数值模型，即分别向下扩展到软基岩和硬基岩，以进行地震现场响应分析。结果表明，简化的数值模型提供了地表运动修正的量化，与实际模型相比，误差通常等于±10%。因此，