Identification of undercover karst areas can be essential for engineering or hydrogeological studies. Geological reconnaissance of karst areas can be challenging due to their complex and highly heterogeneous internal structure. Herein, we present a case study carried out at the carbonate coastal Montgrí Massif in Costa Brava (Spain), which, in the study area, is characterized by a well-developed karst system covered by Quaternary sediments. The objectives of the work are to delineate and characterize karst structures using geophysical techniques and to produce a subsurface geological model that goes beyond the individual physical properties determined independently by each geophysical method. We acquired electrical resistivity and seismic datasets for five collocated profiles. We analyzed the seismic datasets to retrieve P-wave (V_p) and S-wave (V_s) velocity models. Clay-filled karst formations may produce seismic and electrical signatures that are difficult to interpret due to the wide range of values that can be present depending on the properties of the materials the karst's infill. In this type of environment, the Fuzzy c-means (FCM) data clustering approach is a way of producing an integrated model that can help to constrain the lithological interpretation. In this study, FCM is first applied to an electrical resistivity-V_s dataspace in order to characterize near surface sediments. Four different groups are recognized corresponding to different lithologies, fluid conductivities, and saturations in the unconsolidated sediments. Secondly, FCM analysis of the resistivity-V_p datasets provides integrated models that help to delineate the karst areas. The interpretive constraints used derive from the results the first FCM application and the lithological description of a single borehole that reaches the karst below the Quaternary sediments. In this way, karst is identified in all three profiles. This study shows that the integration of seismic and electrical resistivity information using the FCM approach can extend borehole information throughout the study area and thus provide comprehensive geological models in karst environments.

识别地下岩溶地区对于工程或水文地质研究至关重要。由于岩溶地区的内部结构复杂且高度异质，对岩溶地区的地质勘察可能具有挑战性。在此，我们介绍了在布拉瓦海岸（西班牙）的碳酸盐沿海 Montgrí 地块进行的案例研究，该研究区的特征是第四纪沉积物覆盖的发育良好的喀斯特系统。这项工作的目标是使用地球物理技术描绘和表征岩溶结构，并产生一个地下地质模型，该模型超越了由每种地球物理方法独立确定的个体物理特性。我们获得了五个并置剖面的电阻率和地震数据集。我们分析了地震数据集以检索 P 波 (V_p ) 和 S 波 (V _s ) 速度模型。粘土填充的岩溶地层可能会产生难以解释的地震和电信号，因为根据岩溶填充物的材料特性，可能存在的数值范围很广。在这种类型的环境中，模糊 c 均值 (FCM) 数据聚类方法是一种生成有助于约束岩性解释的集成模型的方法。在这项研究中，FCM 首先应用于电阻率-V _s数据空间，以表征近表层沉积物。根据松散沉积物中不同的岩性、流体传导率和饱和度，识别出四个不同的组。二、FCM分析电阻率-V _pdatasets 提供了有助于描绘喀斯特地区的综合模型。所使用的解释约束来自于第一次 FCM 应用的结果和到达第四纪沉积物下方岩溶的单个钻孔的岩性描述。通过这种方式，在所有三个剖面中都确定了岩溶。这项研究表明，使用 FCM 方法整合地震和电阻率信息可以扩展整个研究区域的钻孔信息，从而提供岩溶环境中的综合地质模型。