Strain Rates and Contemporary Deformation in the Snake River Plain and Surrounding Basin and Range From GPS and Seismicity
New horizontal GPS velocities along with earthquakes, faults, and volcanic features are used to assess how strain is accommodated in the Northern Basin and Range Province. We used GPS phase data collected from 1994 to 2007 to estimate horizontal velocities for 132 stations within the Snake River Plain (SRP) and surrounding basin and range. These velocities show regional scale clockwise rotation indicating basal driving forces beyond those associated with the Yellowstone Hotspot. Within the western Centennial Tectonic Belt (CTB), the GPS measurements indicate the basin and range is extending at a rate between 5x10-9/yr and 10x10-9/yr, which is an order of magnitude greater than the strain rate we observe with GPS in the SRP, explaining its low seismicity. Between these two regions is the “Centennial Shear Zone”, a NE-trending zone of right-lateral shear with estimated slip rates that increase northeastward from 0.9±0.3 mm/yr in the SW to 1.7±0.2 mm/yr in NE. We interpret the new GPS velocities to indicate: 1) right-lateral shear may be accommodated by strike-slip earthquakes on NE-trending faults in the Centennial Shear Zone; 2) three basin and range faults (Lost River, Lemhi, and Beaverhead) do not extend into the SRP, but instead terminate at the SRP margin; and 3) extension in the SRP occurs at a much lower rate than the rate of normal faulting in the western CTB.
- Research Organization:
- Idaho National Laboratory (INL)
- Sponsoring Organization:
- DOE - NE
- DOE Contract Number:
- AC07-99ID13727
- OSTI ID:
- 935230
- Report Number(s):
- INL/JOU-08-13800
- Journal Information:
- Geology, Journal Name: Geology Journal Issue: 8 Vol. 36; ISSN 0091-7613; ISSN GLGYBA
- Country of Publication:
- United States
- Language:
- English
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