Mechanical models favor a ramp geometry for the Ventura-pitas point fault, California

Scott T. Marshall, Gareth J. Funning, Hannah E. Krueger, Susan E. Owen, & John P. Loveless

Published January 31, 2017, SCEC Contribution #7073

Recent investigations have provided new and significantly revised constraints on the subsurface structure of the Ventura-Pitas Point fault system in southern California; however, few data directly constrain fault surfaces below ~6 km depth. Here, we use geometrically complex three-dimensional mechanical models driven by current geodetic strain rates to test two proposed subsurface models of the fault system. We find that the model that incorporates a ramp geometry for the Ventura-Pitas Point fault better reproduces both the regional long term geologic slip rate data and interseismic GPS observations of uplift in the Santa Ynez Mountains. The model-calculated average reverse slip rate for the Ventura-Pitas Point fault is 3.5 ± 0.3 mm/yr, although slip rates are spatially variable on the fault surface with > 8 mm/yr predicted on portions of the lower ramp section at depth.

Key Words
Ventura; Pitas Point; Fault; Transverse Ranges; Geodesy; Slip Rate

Citation
Marshall, S. T., Funning, G. J., Krueger, H. E., Owen, S. E., & Loveless, J. P. (2017). Mechanical models favor a ramp geometry for the Ventura-pitas point fault, California. Geophysical Research Letters, 44(3), 1311-1319. doi: 10.1002/2016GL072289. http://onlinelibrary.wiley.com/doi/10.1002/2016GL072289/abstract

Related Projects & Working Groups
Ventura SFSA, Unified Structural Representation (USR), Tectonic Geodesy