Showing papers in "Geoexploration in 1987"

TL;DR: In this paper, the authors used geophysical logs, particularly neutron-neutron and sonic, for estimating overburden strength at ten mine sites in Australia, and derived empirical relationships for estimating uniaxial compressive strength from neutron and sonic log response.

TL;DR: In this paper, a general procedure for computing the effect of non-zero turnoff time on the transient electromagnetic response is presented which can be applied to forward and inverse calculation methods for any transmitter-receiver configuration.

TL;DR: In this article, an iterative fast Fourier procedure is derived for referring to a horizontal plane potential field data measured over a topographic surface, and the convergence of the procedure is studied and it is found that results are satisfactory when the plane is close to the topography, either above, below or intersecting the measurement surface.

TL;DR: In this paper, a transport mechanism in the ground which has the capacity of lifting trace amounts of different elements from the bedrock to the ground surface is described, guided by a funnel system towards a thin membrane on which it is collected.

TL;DR: In this paper, simultaneous Induced Polarization and Vertical Electrical Soundings (IPVES) are used to delineate saltwater intrusions in two regions in the northeastern part of Spain.

TL;DR: A number of experimental high resolution seismic reflection surveys have been carried out in the Sydney Basin, using 48 trace IFP recording equipment with one millisecond sampling, single detectors per trace and small explosive charges as mentioned in this paper.

TL;DR: In this article, an exact inverse operator for the integral equation is obtained as the inverse Laplace transform of the Hankel transform of an electromagnetic response, which is derived as a particular limit case from a nonlinear integral formulation for electromagnetic inverse problems.

TL;DR: In this paper, transient electromagnetic (TEM) measurements with commercial equipment were carried out to attempt to detect conductive zones in situ, and these tests were successful in locating cindered segments of the Bulli seam at a depth of 340 m.

TL;DR: In this article, a simple and fast computer algorithm for automatic picking of refraction first-arrival time is presented, which convolves seismic refraction data with a box-car function of progressively increasing width.

TL;DR: In this paper, a macroscopic physical model for the self-potential of an electronic conductor in an electrolytic homogeneous environment is given, where the potential of the sources is solved numerically with the aid of the integral equation technique.

TL;DR: In this article, a geoelectrical survey was carried out in a test area containing sub-surface anomalous bodies and three focused arrays, tri-, tetra-and penta-electrode arrays were utilized.

TL;DR: In this paper, the authors examined the problems associated with imaging of geological features via tomography and showed that the recovery of tomographic images from field data can be improved by constraining them during processing, using velocity information and information about the survey geometry.

TL;DR: In this paper, a negative residual gravity anomaly with a minimum of −40 g.u. is defined in the region of the Golden Cross fossil hydrothermal system, which is attributed to a local mass loss resulting from Hydrothermal alteration.

TL;DR: In this article, a single term expression is given to calculate the gravitational effect for any square vertical prism with a sloping surface, which is well suited to automatic calculation of the terrain correction when a digital terrain model is available.

TL;DR: Theoretical borehole mise-a-la-masse profiles are generated using the integral equation method for the case of a thin slab-like conductor and an analytical method for a thin disk-like conductor.

TL;DR: In this article, geoelectrical field studies on cavernous Precambrian limestones of the Cuddapah Basin were conducted on an experimental basis in parts of Kurnool district, Andhra Pradesh, India.

TL;DR: In this paper, the applicability of geoelectrical soundings in exploring tumuli was studied and the utility of sounding profiles in order to outline the area occupied by ancient workings was discussed.

TL;DR: In this paper, a method of nonlinear correlation or matching is presented which overcomes some of the difficulties of other techniques, such as the difficulty of finding only one solution, and the present method generates a "function network" of probable interpretations.

TL;DR: The in-seam seismic technique was introduced by the Broken Hill Proprietary Company Limited (BHP) as a means of detecting geological faults ahead of advancing underground coal mine workings.

TL;DR: The applications for in-seam seismic surveying in Australian coal mines are similar to those reported elsewhere as discussed by the authors, however, they are different in the sense that the waveguides are thick and do not often support an Airy phase, and the available surface boreholes allow the extension of the surveying to a face-to-borehole methodology.

TL;DR: In this article, the authors proposed a method to identify subtle anomalies within the channel wave characteristics to detect faulting of the order of 2 m in a coal seam, where the waveguides are often thick (10 m or more) and high absorption appears to be occurring.

TL;DR: In this article, the mise-a-la-masse anomalies are calculated by solving the potential problem for steady current flow in a linear, piecewise homogeneous medium using the Fredholm integral equation of the second kind for the surface charge density.

TL;DR: An extensive seismic refraction survey in the foundation area of the Acheloos river dam (Central Greece) revealed the existence of four layers and the P and S seismic wave velocities of these layers were measured and used in a two-dimensional boundary-element model of the area to determine its dynamic behaviour when subjected to incident SH waves from strong earthquakes as mentioned in this paper.

TL;DR: In this paper, an aperture is placed at the free-surface to admit energy to the inhomogeneous structure from a small portion (a "line" of a wavefront propagating in an auxiliary homogeneous medium defined above the free surface.

TL;DR: In this article, a thin-sheet model is considered which is equivalent to the gradient resistivity structure of stable regions and a numerical algorithm is developed using the FEM-technique.