In recent years, the permanent seismic networks worldwide have largely increased, raising the amount of earthquake signals and the applications using seismic records. Although characterization of the soil properties at recording stations has a large impact on hazard estimates, it has not been implemented so far in a standardized way for reaching high-level metadata. To address this issue, we built an online questionnaire for the identification of the indicators useful for a reliable site characterization at a seismic station. We analysed the answers of a large number of experts in different fields, which allowed us to rank 24 different indicators and to identify the most relevant ones: fundamental frequency (f₀), shear-wave velocity profile (V_S), time-averaged Vs over 30 m (V_S30), depth of seismological and engineering bedrock (H_{seis_bed} and H_{eng_bed}), surface geology and soil class. Moreover, the questionnaire proposed two additional indices in terms of cost and difficulty to obtain a reliable value of each indicator, showing that the selection of the most relevant indicators results from a complex balance between physical relevancy, average cost and reliability. For each indicator we propose a summary report, provided as editable pdf, containing the background information of data acquisition and processing details, with the aim to homogenize site metadata information at European level and to define the quality of the site characterization (see companion paper Di Giulio et al. 2021). The selected indicators and the summary reports have been shared within European and worldwide scientific community and discussed in a dedicated international workshop. They represent a first attempt to reach a homogeneous set of high-level metadata for site characterization.

近年来，世界范围内的永久性地震台网大量增加，增加了地震信号的数量和利用地震记录的应用。尽管记录站土壤特性的表征对灾害估计有很大影响，但迄今为止尚未以标准化方式实施以达到高级元数据。为了解决这个问题，我们建立了一个在线调查问卷，用于识别对地震台站可靠站点特征描述有用的指标。我们分析了不同领域的大量专家的答案，这使我们能够对 24 个不同的指标进行排名并确定最相关的指标：基频 ( f ₀ )、横波速度剖面 ( V _S), 30 m 以上的时间平均Vs ( V _{S 30} ), 地震和工程基岩深度 ( H _{seis_bed}和H _{eng_bed})、地表地质和土壤类。此外，问卷在成本和难度方面提出了两个额外指标，以获得每个指标的可靠值，表明最相关指标的选择是物理相关性、平均成本和可靠性之间复杂平衡的结果。对于每个指标，我们提出了一份总结报告，以可编辑的 pdf 格式提供，其中包含数据采集和处理细节的背景信息，目的是在欧洲层面统一站点元数据信息并定义站点特征的质量（参见配套文件Giulio 等人，2021 年）。选定的指标和总结报告已在欧洲和全球科学界内共享，并在专门的国际研讨会上进行了讨论。