Any stratigraphic reconstruction by means of surface geophysical methods is affected by the nonuniqueness of data inversion and by the resolution-depth trade-off. The combination of different geophysical techniques can reduce the number of degrees of freedom of the problem. We have focused on two low-impact single-station geophysical techniques: microtremor and gravity. These have been used by previous authors for stratigraphic mapping only by comparing the results independently. We suggest a procedure to combine microtremor and gravity data into a unique subsoil model and explore to what extent their combined use can overcome their individual weaknesses and constrain the final result. We apply the procedure to the Bolzano sedimentary basin, Northern Italy, to derive a 3D bedrock model of the basin. We use microtremor data to map the ground resonance frequencies and derive an initial 3D bedrock depth model by assuming a $V_{\mathrm{S}}$ profile for the sediment fill. Then, we define a density model for rock and sediments and perform 3D gravity forward modeling. We then perturb the $V_{\mathrm{S}}$ and density models and find the parameters that best fit the observed gravity anomalies. Data uncertainties are examined to explore the significance of the results. Joint use of the two techniques successfully helps interpret the stratigraphic model: Ground resonance frequencies guarantee the spatial resolution of the bedrock geometry model, whereas gravity data help constrain the frequency to depth conversion.

中文翻译：

---

结合单站微震和重力测量进行深层地层测绘

任何通过地表地球物理方法进行的地层重建都会受到数据反演的非唯一性和分辨率-深度权衡的影响。不同地球物理技术的组合可以减少问题的自由度数。我们专注于两种低影响的单站地球物理技术：微震和重力。以前的作者仅通过独立比较结果，将这些用于地层绘图。我们建议采用一种程序将微震和重力数据结合到一个独特的底土模型中，并探索它们的结合使用在多大程度上可以克服各自的弱点并限制最终结果。我们将该程序应用于意大利北部的 Bolzano 沉积盆地，以推导出该盆地的 3D 基岩模型。${伏}_{\mathrm{秒}}$沉积物填充剖面。然后，我们定义岩石和沉积物的密度模型并执行 3D 重力正演建模。然后我们扰乱${伏}_{\mathrm{秒}}$和密度模型，并找到最适合观察到的重力异常的参数。检查数据的不确定性以探索结果的重要性。联合使用这两种技术成功地帮助解释了地层模型：地面共振频率保证了基岩几何模型的空间分辨率，而重力数据有助于限制频率到深度的转换。