Abstract: For complex，historically incompletely backfilled old mines where personnel access to working faces for 3D laser scanning，geological exploration，or drilling operations is restricted due to safety concerns，accurately determining the volume of goafs becomes challenging. To investigate the oc⁃ currence status and distribution of these goafs，a combined geophysical method utilizing ground-based microtremor surveying and induced polarization sounding was employed to delineate the spatial distribu⁃ tion of goafs both horizontally and vertically. Results indicate that by implementing high-density（20 m spacing between measurement points）microtremor surveying integrated with IP sounding，the estimated volume of goafs reached approximately 1.36 million m³，showing only a 5.6% deviation from the statisti⁃ cally documented volume of 1.44 million m³. The integration of microtremor surveying and induced polar⁃ ization sounding effectively identified the geometry and distribution of the voids，yielding reliable and credible results. By summarizing the application of geophysical prospecting techniques in detecting old goafs at a specific mine，this study demonstrates that the combined method of high-density surface micro⁃ tremor surveying and induced polarization sounding provides a solid technical foundation and support for identifying hidden disaster-causing factors of goafs. It enables the accurate characterization of the three�dimensional configuration of old goafs and proves to be a practical and feasible approach for void detec⁃ tion.

Key words: old goaf, hidden disaster-causing factors, geophysical prospecting, microtremor detec? tion, induced polarization sounding