Natural-frequency concept utilized in remote probing of the earth

Abstract

The complete time-domain fields due to a vertical magnetic dipole on the surface of a two-layered earth model are derived in an analytical form using the natural-frequency concept. In these expressions, the displacement currents in the earth's layers are taken into consideration. The step responses of the induced voltage in a horizontal receiving loop is found to have definite diagnostic features for the ground beneath. These features are demonstrated by numerical results and shown by figures. The clear distinction between the step response of the homogeneous and the two-layered ground suggests that this response can be used for the detection of the stratification. PACS Nos.: 41.20.Jb, 42.25.Bs, 42.25.Gy, 44.05.+e