The reflection moveouts of SH-waves reflected from a transversely isotropic layer with tilted symmetry axis computed by the modified hyperbolic equation and Fermat’s principle fit well to the physical data. Their reflection points will shift away from the common midpoint when the symmetry axes are not vertical and horizontal.

A modified EOM method is developed for PS-wave migration based on the equivalent offset migration (EOM) for P-waves and an equivalent PS-wave velocity. A 2D3C seismic case study shows that the method can give better imaging quality than the conventional CCP method by reducing discretisation errors and suppressing noise.

Under the assumption of the equivalent velocity, the converted wave can be easily migrated in the time domain based on the equivalent offset method (EOM). In this paper, the analysis of errors caused by the introduction of the equivalent velocity for the PS-wave and the conditions for applying common scatterpoint (CSP) gathers are presented.

Dissolution of limestone in a karst area resulted in ground shakes and enhancement of fractures. Gravity and electro-resistivity profiles mapped concealed caves, determined groundwater level, and defined five risk areas by correlating gravity lows with caves and conductive zones with brine water, providing information for future hydrological and geotechnical work.

In this study, we developed a forward modelling algorithm with the staggered-grid finite-difference method. The elastic wave propagation in 2D tilted transversely isotropic media is well simulated using this algorithm. We also implement convolutional perfectly matched layer absorbing boundaries in our algorithm in order to handle the artificial boundary reflection efficiently.

The polarimetric borehole radar has the ability to characterise subsurface fractures. Nine fracture sets were characterised into four category fractures depending on polarimetric analysis of alpha, entropy and anisotropy decomposition. Validation of these results was implemented by numerical simulation for a synthesised fractures property using the Finite Difference Time Domain method.

The use of incorrect values of the formation constants a (tortuosity factor) and m (cementation exponent) in Archie’s water saturation equation can result in the overlooking of potential producible zones. This work illustrates a simple method of calculating a and m that is dependent on sonic transit time and bulk density, and on knowing one cementation exponent value from core measurements.

This case study compares 3D inversion results from SPECTREM 2000 fixed-wing time-domain airborne electromagnetic (AEM) and ZTEM airborne audio-frequency magnetics (AFMAG) systems flown over the Pebble Cu–Au–Mo porphyry deposit in south-western Alaska. Both 3D inversions recover conductors coincident with alteration associated with both Pebble East and Pebble West.

Using a discrete conductor model it is possible to generate a cross-sectional image that shows the sensitivity of different airborne electromagnetic systems. This can be used to estimate the depth and width of investigation and can therefore be used to determine the optimal line spacing of airborne electromagnetic surveys.

This paper describes the application of Tukey’s Biweight norm using the IRLS (iteratively reweighted least squares) algorithm as a robust inversion in seismic application and shows its possible improvement in robustness over the l₁ norm inversion when dealing with data having many outliers.

Network extraction is a routine applied to magnetic data to identify lineaments (e.g. faults and dykes). When these extracted lineaments are used in conjunction with existing geophysical and geological data, vectors for mineral potential may be identified. Network extraction was successfully applied to an aeromagnetic data set from Northwestern Canada.

We show the application of simulated annealing to optimise our estimation of the parameters in the common reflection surface (CRS) stack method. This approach using numerically modelled data and multichannel marine seismic data around the Median Tectonic Line in Japan provides a clear seismic profile with a high signal-to-noise ratio.