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

  • Author(s): Marshall, ST
  • Funning, GJ
  • Krueger, HE
  • Owen, SE
  • Loveless, JP
  • et al.
Abstract

©2017. American Geophysical Union. All Rights Reserved. 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.

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