Seismic cycle and rheological effects on estimation of present-day slip rates for the Agua Blanca and San Miguel-Vallecitos faults, northern Baja California, Mexico

Timothy Dixon, Julien Decaix, Fred Farina, Kevin Patrick Furlong, Rocco Malservisi, Richard Bennett, Francisco Suarez-Vidal, John Fletcher, Jeff Lee

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Geodesy can be used to infer long-term fault slip rates, assuming a model for crust and upper mantle rheology. We examine the sensitivity of fault slip rate estimates to assumed rheology for the Agua Blanca and San Miguel-Vallecitos faults in northern Baja California, Mexico, part of the Pacific-North America plate boundary zone. The Agua Blanca fault is seismically quiet, but offset alluvial fans indicate young activity. Current seismicity is confined to the nearby San Miguel-Vallecitos fault, a small offset fault better aligned with plate motion. GPS measurements between 1993 and 1998 suggest that both faults are active, with a combined slip rate of 4-8 mm yr-1 regardless of rheological model. However, slip rate estimates for the individual faults are sensitive to assumed rheology. Elastic half-space models yield 2-3 mm yr-1 for the Agua Blanca fault, and somewhat faster rates for the San Miguel-Vallecitos fault, 2-4 mm yr-1, with uncertainties of about 1 mm yr-1. Models incorporating viscoelastic rheology and seismic cycle effects suggest a faster slip rate for the Agua Blanca fault, 6 ± 1 mm yr-1, and a slower rate for the San Miguel-Vallecitos fault, 1 ± 1 mm yr-1, in better agreement with geological data, but these rates are sensitive to assumed rheology. Numerical simulations with a finite element model suggest that for similar rheological and friction conditions, slip on the San Miguel-Vallecitos fault should be favored due to better alignment with plate motion. Long-term faulting processes in the larger offset Agua Blanca fault may have lowered slip resistance, allowing accommodation of motion despite misalignment with plate motion.

Original languageEnglish (US)
JournalJournal of Geophysical Research: Solid Earth
Volume107
Issue number10
StatePublished - Oct 10 2002

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Lower California (Mexico)
slip rate
Mexico
rheology
Rheology
slip
Fault slips
cycles
plate motion
geodesy
Geodesy
Faulting
fault slip
friction
Fans
Global positioning system
uncertainty
effect
Friction
accommodation

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  • Geophysics
  • Oceanography
  • Forestry
  • Aquatic Science
  • Ecology
  • Condensed Matter Physics
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Materials Chemistry
  • Palaeontology

Cite this

Dixon, Timothy ; Decaix, Julien ; Farina, Fred ; Furlong, Kevin Patrick ; Malservisi, Rocco ; Bennett, Richard ; Suarez-Vidal, Francisco ; Fletcher, John ; Lee, Jeff. / Seismic cycle and rheological effects on estimation of present-day slip rates for the Agua Blanca and San Miguel-Vallecitos faults, northern Baja California, Mexico. In: Journal of Geophysical Research: Solid Earth. 2002 ; Vol. 107, No. 10.
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abstract = "Geodesy can be used to infer long-term fault slip rates, assuming a model for crust and upper mantle rheology. We examine the sensitivity of fault slip rate estimates to assumed rheology for the Agua Blanca and San Miguel-Vallecitos faults in northern Baja California, Mexico, part of the Pacific-North America plate boundary zone. The Agua Blanca fault is seismically quiet, but offset alluvial fans indicate young activity. Current seismicity is confined to the nearby San Miguel-Vallecitos fault, a small offset fault better aligned with plate motion. GPS measurements between 1993 and 1998 suggest that both faults are active, with a combined slip rate of 4-8 mm yr-1 regardless of rheological model. However, slip rate estimates for the individual faults are sensitive to assumed rheology. Elastic half-space models yield 2-3 mm yr-1 for the Agua Blanca fault, and somewhat faster rates for the San Miguel-Vallecitos fault, 2-4 mm yr-1, with uncertainties of about 1 mm yr-1. Models incorporating viscoelastic rheology and seismic cycle effects suggest a faster slip rate for the Agua Blanca fault, 6 ± 1 mm yr-1, and a slower rate for the San Miguel-Vallecitos fault, 1 ± 1 mm yr-1, in better agreement with geological data, but these rates are sensitive to assumed rheology. Numerical simulations with a finite element model suggest that for similar rheological and friction conditions, slip on the San Miguel-Vallecitos fault should be favored due to better alignment with plate motion. Long-term faulting processes in the larger offset Agua Blanca fault may have lowered slip resistance, allowing accommodation of motion despite misalignment with plate motion.",
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Seismic cycle and rheological effects on estimation of present-day slip rates for the Agua Blanca and San Miguel-Vallecitos faults, northern Baja California, Mexico. / Dixon, Timothy; Decaix, Julien; Farina, Fred; Furlong, Kevin Patrick; Malservisi, Rocco; Bennett, Richard; Suarez-Vidal, Francisco; Fletcher, John; Lee, Jeff.

In: Journal of Geophysical Research: Solid Earth, Vol. 107, No. 10, 10.10.2002.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Seismic cycle and rheological effects on estimation of present-day slip rates for the Agua Blanca and San Miguel-Vallecitos faults, northern Baja California, Mexico

AU - Dixon, Timothy

AU - Decaix, Julien

AU - Farina, Fred

AU - Furlong, Kevin Patrick

AU - Malservisi, Rocco

AU - Bennett, Richard

AU - Suarez-Vidal, Francisco

AU - Fletcher, John

AU - Lee, Jeff

PY - 2002/10/10

Y1 - 2002/10/10

N2 - Geodesy can be used to infer long-term fault slip rates, assuming a model for crust and upper mantle rheology. We examine the sensitivity of fault slip rate estimates to assumed rheology for the Agua Blanca and San Miguel-Vallecitos faults in northern Baja California, Mexico, part of the Pacific-North America plate boundary zone. The Agua Blanca fault is seismically quiet, but offset alluvial fans indicate young activity. Current seismicity is confined to the nearby San Miguel-Vallecitos fault, a small offset fault better aligned with plate motion. GPS measurements between 1993 and 1998 suggest that both faults are active, with a combined slip rate of 4-8 mm yr-1 regardless of rheological model. However, slip rate estimates for the individual faults are sensitive to assumed rheology. Elastic half-space models yield 2-3 mm yr-1 for the Agua Blanca fault, and somewhat faster rates for the San Miguel-Vallecitos fault, 2-4 mm yr-1, with uncertainties of about 1 mm yr-1. Models incorporating viscoelastic rheology and seismic cycle effects suggest a faster slip rate for the Agua Blanca fault, 6 ± 1 mm yr-1, and a slower rate for the San Miguel-Vallecitos fault, 1 ± 1 mm yr-1, in better agreement with geological data, but these rates are sensitive to assumed rheology. Numerical simulations with a finite element model suggest that for similar rheological and friction conditions, slip on the San Miguel-Vallecitos fault should be favored due to better alignment with plate motion. Long-term faulting processes in the larger offset Agua Blanca fault may have lowered slip resistance, allowing accommodation of motion despite misalignment with plate motion.

AB - Geodesy can be used to infer long-term fault slip rates, assuming a model for crust and upper mantle rheology. We examine the sensitivity of fault slip rate estimates to assumed rheology for the Agua Blanca and San Miguel-Vallecitos faults in northern Baja California, Mexico, part of the Pacific-North America plate boundary zone. The Agua Blanca fault is seismically quiet, but offset alluvial fans indicate young activity. Current seismicity is confined to the nearby San Miguel-Vallecitos fault, a small offset fault better aligned with plate motion. GPS measurements between 1993 and 1998 suggest that both faults are active, with a combined slip rate of 4-8 mm yr-1 regardless of rheological model. However, slip rate estimates for the individual faults are sensitive to assumed rheology. Elastic half-space models yield 2-3 mm yr-1 for the Agua Blanca fault, and somewhat faster rates for the San Miguel-Vallecitos fault, 2-4 mm yr-1, with uncertainties of about 1 mm yr-1. Models incorporating viscoelastic rheology and seismic cycle effects suggest a faster slip rate for the Agua Blanca fault, 6 ± 1 mm yr-1, and a slower rate for the San Miguel-Vallecitos fault, 1 ± 1 mm yr-1, in better agreement with geological data, but these rates are sensitive to assumed rheology. Numerical simulations with a finite element model suggest that for similar rheological and friction conditions, slip on the San Miguel-Vallecitos fault should be favored due to better alignment with plate motion. Long-term faulting processes in the larger offset Agua Blanca fault may have lowered slip resistance, allowing accommodation of motion despite misalignment with plate motion.

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