Reliability of 2D kinematic fold models to infer deep fault structure in the western Transverse Ranges, California

Craig Nicholson

Published July 1, 1998, SCEC Contribution #1581

The western Transverse Ranges are one of the most active tectonic regions of the world. In the Ventura Basin, faults and folds accommodate high rates of oblique crustal strain and uplift rates exceed 10 mm/yr. The 1994 M6.7 Northridge earthquake occurred on a blind, south-dipping fault beneath the San Fernando Valley that is considered part of the the same fault and fold system that extends westward into the Ventura Basin and eastern Santa Barbara Channel. These active fault structures represent a significant seismic hazard to a large urban population, yet little is understood about these active structures or about the hazard associated with these blind faults, because little has been done to document the nature or subsurface geometry of these structures in 3D. In fact, much of what is "known" about these active faults and their associated folds has been inferred from simple 2D balanced cross sections models, many of which have only limited subsurface control. The fundamental question is: Are any of these 2D balanced cross section models reliable as they are currently applied to the western Transverse Ranges--especially in areas of oblique convergence?

Citation
Nicholson, C. (1998, 07). Reliability of 2D kinematic fold models to infer deep fault structure in the western Transverse Ranges, California. Poster Presentation at NEHRP Conference and Workshop on Research on the Northridge, California Earthquake of January 17, 1994.