Abstract Surface substrates are fundamental materials that nurture and sustain natural resources on the Earth’s surface. The combined application of electrical resistivity tomography (ERT) and active and passive surface wave method (SWM) significantly improves the reliability of shallow subsurface structural interpretation; however, studies focusing on the vertical structure of surface substrates using the integrated ERT-SWM approach remain limited. We aimed to systematically investigate the vertical structural characteristics of surface substrates in this emerging research field. We selected the Liaohe Alluvial Plain of China as a representative area and innovatively employed an integrated geophysical exploration system combining ERT and active and passive SWM. The ERT method showed high sensitivity to sand-clay interbeds and moisture content variations. In contrast, the active and passive SWM effectively evaluates variations in mechanical properties, such as the degree of compaction within the substrate layers. By combining ERT with active and passive SWM and constraining and validating the inversion results using borehole data, the joint interpretation of both methods significantly improved the accuracy of vertical stratification of surface substrates, demonstrating their complementary advantages. Although the resolution of local thin layers and interbeds remains limited, the overall lithological sequence shows high consistency with borehole logging data, confirming the reliability of the geophysical methods. This study provides important support for improving surface substrates investigation systems and holds significant theoretical and practical value for advancing the development of three-dimensional natural resource surveys and monitoring.
Zhang et al. (Thu,) studied this question.