USING HIGH RESOLUTION TOPOGRAPHIC DATA TO ILLUMINATE DISCRETE STRUCTURAL DOMAINS AND RELATIVE RATES OF ACTIVE TECTONICS, IN THE CAMARILLO FOLD BELT: VENTURA COUNTY, SOUTHERN CALIFORNIA

The Camarillo Fold Belt (CFB), in the western Transverse Ranges, presents a potentially serious earthquake hazard to millions of people living in southern California, yet it has not been studied as a unit for the purpose of evaluating the seismic hazard. Much of the fold belt is completely urbanized or in use as agricultural lands, therefore, we utilize high-resolution (3m) Digital Elevation Model (DEM) to assess the relative rates of deformation across the region, lateral propagation of discrete folds or fold complexes, as well as, to illuminate subsurface structures that may have controlled fault and fold growth through time.

Based on our DEM-analysis, bedrock mapping, and subsurface data, we identify four discrete structural domains in the CFB, which are separated by fault segment boundaries that are typically characterized by orthogonal cross-faults. Adjacent structural domains are locally characterized by, as much as, a 3-fold change in watershed erosion, abrupt changes in hypsometry and hillslope angles, and sedimentologic and thickness changes in late Pleistocene bedrock. This analysis suggests that active folding above discrete fault segments, in the CFB, are younging to the south and west with time. Additionally, transverse faults that were active during Miocene time and acted to limit fault growth, continue to serve as segment boundaries that control Quaternary fold growth, and may serve to limit the magnitude of a given earthquake rupture.