WILLACY, C. N., K. R. McCLAY, and D. A. WALTHAM, Fault Dynamics Project, Geology Department, University of London, Egham, Surrey, England

ABSTRACT: The Tomography of Three Dimensional Sandbox Models

Analog models of extensional and compressional environments have been developed to observe kinematics, geometry and interaction within multiple fault systems. Techniques are presented to analyse information contained within these models by the production of three dimensional data sets that describe their evolution. High powered workstations facilitate the interpretation of the models using these techniques, and give greater insight into fault development previously unobserved.

Data can be obtained in one of two ways. Firstly, sectioning of the models produces two dimensional profiles which can be digitised into the computer. Surfaces are produced by interpolation between adjacent profiles. This method produces excellent resolution provided there is good coverage across the area of interest. Secondly, voxel based CAT scan information is used to build tomographic images of internal architectures throughout the body of the models. Pre-processing of the data is undertaken to highlight fault propagation and the complicated interactions between coexisting faults. The role of dilatancy during the evolution of faults can be observed within these models and gives a greater understanding of more complicated processes such as fluid migration pathways that exist on maj r crustal faults within the earth. Memory requirements are greater for this data type although the change in the physical properties of the materials involved can be determined and this is an advantage over the previous technique. Examples of profiles from the models can be compared with seismic sections.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.