Evidence for composite hydraulic architecture in an active fault system based on 3D seismic reflection, time-domain electromagnetics and temperature data
S. Hess, J.P. Fairley, J. Bradford, M. Lyle and W. Clement
Issue: Vol 7, No 5-6, October 2009 pp. 341 - 352
Special Topic: Hydrogeophysics - Methods and Processes
Info: Article, PDF ( 5.45Mb )
Fault hydrology is a topic of scientific and practical importance but considerable uncertainty exists regarding the nature of structural controls on fluid flow. Here we use seismic reflection and time-domain electromagnetic data to develop a three-dimensional model of hydraulic architecture in a predominantly dip-slip normal fault system and we predict the architectural elements based on subsurface fluid flow patterns inferred from near-surface temperature measurements. Our observations indicate the presence of high-permeability flow paths parallel to fault planes in poorly-lithified sediments. These results are best explained using a combination of elements from commonly accepted conceptual models of fault architecture, a finding that exhibits the heterogeneous nature of the geologic materials comprising the site. These insights may be useful as a guide to future studies of active fault systems, where multiple-mode investigations (geophysical, hydrologic, thermal, geochemical) will be required to better understand subsurface fluid/fault interactions.