Detection of Abandoned Coal Mine Goaf in China’s Ordos Basin Using the Transient Electromagnetic Method; [Untersuchung des Alten Mannes in Altbergbauen im Ordos Becken in China mit transienter Elektromagnetik (TEM)]; [Detección de los hoyos de una mina de carbón abandonada en la Cuenca de Ordos de China mediante el sondeo electromagnético transitorio]

Early coal mining and management methods left a large number of unknown goafs in China’s important Ordos Basin, which has restricted the safe production in today’s large-scale mines. The transient electromagnetic (TEM) method is the main geophysical tool used to detect the goaf. We considered the geological conditions of Ordos Basin in studying the optimal working parameters, electromagnetic (EM) interference, and terrain influence. The numerical simulation results of primary and secondary fields show that the most powerful abnormal signal can be obtained for the common 100 m deep goaf of the Ordos Basin by using a loop at least 240 m × 240 m. Time compensation and a polynomial fitting algorithm can be used to separate and weaken the TEM signal’s EM noise. The terrain height difference mainly affects TEM’s depth parameters, which can be modified to correct the topographic influence by considering the lateral continuity of the sedimentary strata. Three successful detection cases show that the study’s results can be used effectively in the Ordos Basin. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.