The vibration modes of the ground have been described both in the 1D and 2D case. The 1D resonance is found on geological structures whose aspect ratio is low, that is on layers with a lateral width much larger than their thickness. A typical example is that of a horizontal soft sediment layer overlying hard bedrock. In this case, the 1D resonance frequency, traditionally detected by means of the microtremor H/V technique, depends on the bedrock depth and on the shear wave velocity of the resonating cover layer. The H/V technique is thus used both to map the resonance frequencies in seismic microzonation studies and for stratigraphic imaging. When 2D resonance occurs, generally on deep and narrow valleys, the whole sedimentary infill vibrates at the same frequency and stratigraphic imaging can no longer be performed by means of the 1D resonance equation. Understanding the 1D or 2D resonance nature of a site is therefore mandatory to avoid wrong stratigraphic and dynamic interpretations, which is in turn extremely relevant for seismic site response assessment. In this paper we suggest a procedure to address this issue using single station approaches, which are much more common compared to the multi-station synchronized approach presented by research teams in earlier descriptions of the 2D resonances. We apply the procedure to the Bolzano sedimentary basin in Northern Italy, which lies at the junction of 3 valleys, for which we observed respectively 1D-only, 1D and 2D, and 2D-only resonances. We conclude by proposing a workflow scheme to conduct experimental measurements and data analysis in order to assess the 1D or 2D resonance nature of a site using a single station approach.

中文翻译：

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通过单站方法检测1D和2D地面共振

在1D和2D情况下均已描述了地面的振动模式。一维共振出现在纵横比低的地质结构上，即横向宽度比其厚度大得多的层上。一个典型的例子是覆盖坚硬基岩的水平软质沉积层。在这种情况下，传统上通过微震H / V技术检测的一维共振频率取决于基岩深度和共振覆盖层的剪切波速度。因此，H / V技术既可用于在地震微带研究中绘制共振频率，也可用于地层成像。当发生2D共振时，通常在深而窄的山谷中，整个沉积物填充物都以相同的频率振动，并且不再可以通过一维共振方程进行地层成像。因此，必须了解位置的1D或2D共振性质，以避免错误的地层和动力解释，这反过来又与地震现场响应评估极为相关。在本文中，我们提出了一种使用单站方法解决此问题的方法，与研究团队在2D共振的较早描述中提出的多站同步方法相比，这种方法更为常见。我们将该程序应用于意大利北部的博尔扎诺沉积盆地，该盆地位于3个山谷的交界处，为此我们分别观测到仅1D，1D和2D和仅2D共振。