High-resolution tomographic images obtained from crosshole geophysical measurements have the potential to provide valuable information about the geostatistical properties of unsaturated-zone hydrologic-state variables such as moisture content. Under drained or quasi-steady-state conditions, the moisture content will reflect the variation of the physical properties of the subsurface, which deter...

We have developed a case study of crosshole seismic tomography with a cross-firing geometry in which seismic sources were placed in two vertical boreholes alternatingly and receiver arrays were placed in another vertical borehole. There are two crosshole seismic data sets in a conventional sense. These two data sets are used jointly in seismic tomography. Because the local sediment is dominated...

Ground-penetrating radar GPR attenuation-difference analysis can be a useful tool for studying fluid transport in the subsurface. Surface-based reflection attenuation-difference tomography poses a number of challenges that are not faced by crosshole attenuation surveys. We create and analyze a synthetic attenuation-difference GPR data set to determine methods for processing amplitude changes an...

Petrophysical information is sometimes available from well logs, laboratory measurements, etc. It has been shown that incorporation of such information into geophysical inversions can greatly improve the recovered models. However, when the known petrophysical information is not applicable throughout the entire region, the application of petrophysical constraints to geophysical inversions could ...

Inversion based on L2 norm has been widely used in geophysical problems. However, L2 inversion is only capable of recovering smooth features. To obtain sharp boundaries, non-L2 inversion has been used successfully. In reality, however, both smooth and blocky features can be present in the subsurface physical property or interfaces to be recovered. To deal with this situation, we propose a new m...

An overview of the geophysical tomography interpretation method is presented. Two approaches are reviewed, (1) deterministic tomography inversion, developed for rock elasticity investigations, and (2) probability tomography imaging, developed in the domain of potential field methods. The theoretical basis of both approaches is initially outlined, then selected laboratory and field applications ...

Full waveform inversion with frequency sweeping cannot start from zero frequency because of the lack of low-frequency data, requiring a good starting model. We study a different iterative scheme where the notion of proximity of two traces is not the usual least-squares distance, but instead involves registration as in image processing. In order to create transported data, we introduce a nonconv...

When an inverse problem can be formulated so the data are minima of one of the variational problems of mathematical physics, feasibility constraints can be found for the nonlinear inversion problem. These constraints guarantee that optimal solutions of the inverse problem lie in the convex feasible region of the model space. Furthermore, points on the boundary of this convex region can be found...