| Abstract: | Information on the mass and the spatial location of an arbitrary source body can be obtained by performing suitable integrations of 3D gravity and magnetic data along an infinite straight line. No assumptions on the density/magnetization distribution or the shape and location of the source are required. For an oblique borehole, a relationship between the lower limit of the source mass and the distance to the body is obtained. The mass contrast and the magnetic moment of the source can also be estimated. For a vertical borehole, both gravity and vertical magnetic component anomalies have equal areas to the left and right of the depth axis. The particular case of a horizontal gallery not intersecting the body is also studied. If the source is intersected, a lower limit is estimated for the maximum thickness of the body along the gallery. Information on the vertical coordinate of the centre of mass of the source can also be obtained. Numerical tests with synthetic gravity data support the theoretical results. |
