ABSTRACT The inversion of active surface‐wave data is highly affected by the non‐uniqueness of the solution. While a deterministic approach is generally chosen due to certain advantages, there is the risk of getting trapped in a local minima, especially when no a priori information is available about the sub‐surface geometry since the layer thickness is assumed fixed to a priori. The fixed‐layer thickness in a deterministic inversion of the active surface‐wave raises significant issues, such as the relevance of the initial model geometry (the thickness of the intermediate layer and the total depth of the initial model) and the equivalence problems. Thus, the inversion result is inherently not reliable, even in the case of the normal dispersion medium, and the result could be unachievable in challenging sub‐surface situations. These issues could be reduced by using a joint inversion approach. The present paper first presents examples of issues through four case histories in Trabzon, Turkey. Then, two joint inversion approaches based on local search are carried out to handle the issues concerning individual inversion. The first approach combines active surface‐wave data with electric sounding data and the second includes travel times from seismic refraction data. In addition, an independent inversion is carried out with a neighbourhood algorithm for a global search to compare against the joint inversion results. The joint inversion schemes clearly reduce the ambiguities of the individual inversion of the active surface‐wave data, and the dependence on the initial model regarding the layer thickness is also mitigated. Moreover, the joint inversion approach provides an estimate of the complementary model parameters, namely electrical resistivity and the compressional wave velocity. It is shown that the proposed joint inversion approaches provide consistent results with former boreholes, seismic tomographic profiles and the known geologic features of the study area even in the absence of any a priori information.

中文翻译：

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通过地球物理数据联合反演获得可靠的横波速度深度剖面：结合有源表面波、地震折射和电测深数据

摘要 有源面波数据的反演受解的非唯一性的影响很大。虽然由于某些优点通常选择确定性方法，但存在陷入局部最小值的风险，特别是当没有关于地下几何形状的先验信息时，因为层厚度被假定为先验固定。有源表面波确定性反演中的固定层厚度提出了重要问题，例如初始模型几何形状（中间层的厚度和初始模型的总深度）和等效问题的相关性。因此，即使在正常分散介质的情况下，反演结果本质上也不可靠，并且在具有挑战性的地下情况下，结果可能无法实现。这些问题可以通过使用联合反演方法来减少。本文件首先通过土耳其特拉布宗的四个案例历史介绍问题示例。然后，采用两种基于局部搜索的联合反演方法来处理个别反演问题。第一种方法将有源表面波数据与电测深数据相结合，第二种方法包括地震折射数据的走时。此外，使用邻域算法进行独立反演进行全局搜索，以与联合反演结果进行比较。联合反演方案明显减少了有源面波数据单独反演的模糊性，并且也减轻了对初始模型对层厚的依赖。而且，联合反演方法提供了互补模型参数的估计，即电阻率和压缩波速度。结果表明，即使在没有任何先验信息的情况下，所提出的联合反演方法也能提供与研究区以前钻孔、地震层析剖面和已知地质特征一致的结果。