Document Type
Article
Department or Administrative Unit
Geological Sciences
Publication Date
12-1-2000
Abstract
We use new models for present‐day Pacific‐North America motion to evaluate the tectonics of offshore regions west of the Californias. Vandenburg in coastal Alta California moves at the Pacific plate velocity within uncertainties (∼1 mm/yr) after correcting for strain accumulation on the San Andreas and San Gregorio‐Hosgri faults with a model that includes a viscoelastic lower crust. Modeled and measured velocities at coastal sites in Baja California south of the Agua Blanca fault, a region that most previous models consider Pacific plate, differ by 3–8 mm/yr, with coastal sites moving slower that the Pacific plate. We interpret these discrepancies in terms of strain accumulation on known on‐shore faults, combined with right lateral slip at a rate of 3–4 mm/yr on additional faults offshore peninsular Baja California in the Pacific. Offshore seismicity, offset Quaternary features along the west coast of Baja California, and a discrepancy between the magnetically determined spreading rate in the Gulf Rise and the total plate rate from a geological model provide independent evidence for a “Baja California shear zone.”
Recommended Citation
Dixon, Timothy; Farina, Fred; DeMets, Charles; Suarez-Vidal, Francisco; Fletcher, John; Marquez-Azua, Bertha; Miller, M. Meghan; Sanchez, Osvaldo; and Umhoefer, Paul, "New kinematic models for Pacific‐North America Motion from 3 Ma to Present, II: Evidence for a “Baja California Shear Zone”" (2000). All Faculty Scholarship for the College of the Sciences. 286.
https://digitalcommons.cwu.edu/cotsfac/286
Journal
Geophysical Research Letters
Rights
Copyright 2000 by the American Geophysical Union.
Included in
Geology Commons, Geomorphology Commons, Geophysics and Seismology Commons, Tectonics and Structure Commons
Comments
This article was originally published in Geophysical Research Letters. The full-text article from the publisher can be found here.