Linking Seismic and Sub-Seismic Fault Predictions Using Laser Scanning of Outcrop Analogues

Jones, Richard R.¹, Dave Healy², Jonathan Imber², Ruth Wightman², Kenneth J.W. McCaffrey², Robert E. Holdsworth² (1) Dept. of Earth Sciences, Durham, United Kingdom (2) Durham University, Durham, United Kingdom

Although fault models derived from seismic reflection data often provide an excellent view of 3D fault geometries at a large scale, outcrop analogues can give additional geometric and kinematic constraints to help bridge the critical scale-gap needed to integrate seismic and borehole datasets. We use terrestrial laser scanning (ground-based LiDAR) to carry out precise measurements of the 3D geometry of well exposed fracture surfaces. A case study using regular laser-scanning of an active opencast coal mine, provides additional constraint, with 3D fault geometries sequentially revealed throughout the rock volume, as the coal face progressively migrates with time.

The laser scan data provide unprecedented detail and allow spatial variation in various fracture attributes to be quantified, including 3D curvature, fracture connectivity, branch-line geometry, relationship between corrugations and fault splays, detailed fault throw profiles, and the spatial correlation between fracture density and fold curvature. Measurement of such fracture parameters, collected from a range of outcrop analogues, provides direct quantitative input for calibration of geomechanical models, and for validation of fracture networks derived by deterministic or stochastic methods.