Local site evaluation is an essential step in understanding the amplification of seismic motion induced by the complex geological structure and their estimation for future strong earthquakes in urban regions. One of the critical parameters on evaluating amplification effects is the depth of the geophysical bedrock, whose interface to soft sediments is responsible for the development of destructive resonance phenomena. The present study is focused on the estimation of the geophysical bedrock depth along the extra-Carpathian area of Romania (Moesian Platform and surroundings) by correlating and interpolating the results obtained from single station measurements with the available geological/geophysical data. Each site was investigated through the computation of horizontal-to-vertical (H/V) spectral ratios from three-component single station measurements of ambient vibrations. The geophysical bedrock depth was computed using a two-step inversion scheme, based on the retrieval of the Rayleigh-wave ellipticity peak at each seismic station using a regional generic velocity profile. The fundamental frequency of resonance reaches the lowest value in the deepest side (0.07 Hz) and is rising to 13 Hz in the South of the Moesian Platform, where a shallow bedrock is present. The computed bedrock depths (from 30 to ~ 3100 m) show a dipping tendency towards the Southern Carpathians and complex features such as local outcrops and lateral depth variations superpose this gradually dipping trend. In the Carpathian foreland, the bedrock is interpreted as the transition between different sediment layers of Neogene, while outside this area as the Neogene—Cretaceous transition.

中文翻译：

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使用罗马尼亚喀尔巴阡山脉外地区的单站分析和地球物理数据估算地球物理基岩深度

局部场地评价是理解复杂地质结构引起的地震运动放大及其对未来城市地区强地震的估计的重要步骤。评估放大效应的关键参数之一是地球物理基岩的深度，其与软沉积物的界面是破坏性共振现象发展的原因。本研究的重点是通过将单站测量获得的结果与可用的地质/地球物理数据相关联和内插，估算沿罗马尼亚喀尔巴阡山脉外地区（莫西台地和周围环境）的地球物理基岩深度。通过从环境振动的三分量单站测量计算水平到垂直 (H/V) 光谱比来研究每个站点。地球物理基岩深度是使用两步反演方案计算的，基于使用区域通用速度剖面对每个地震台站的瑞利波椭圆度峰值的反演。共振的基频在最深侧达到最低值（0.07 Hz），并在存在浅基岩的 Moesian 平台南部上升至 13 Hz。计算的基岩深度（从 30 到~3100 m）显示出向南喀尔巴阡山脉倾斜的趋势，局部露头和横向深度变化等复杂特征叠加在这种逐渐倾斜的趋势上。在喀尔巴阡山脉，