Transient electromagnetic response characteristics of an underground high resistivity cave and practical detection effect

The authors calculated the transient electromagnetic response for a sphere and measured the transient electromagnetic method (TEM) response results of a high resistivity sphere buried in a low resistivity surrounding rocks in a model experiment, and achieved the transient electromagnetic response features of the high resistivity sphere object. An exploration for a deep-buried soil cave filled with air was conducted by TEM and the results shows that the transient electromagnetic response of high resistivity cave is similar as in the model experiment. It is concluded that the electromagnetic method is effective in detecting high resistivity targets although the extent of high resistivity anomaly is larger than that of the real cave.