A model for earthquakes near Palisades Reservoir, southeast Idaho
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Abstract
The Palisades Reservoir seems to be triggering earthquakes: epicenters are concentrated near the reservoir, and quakes are concentrated in spring, when the reservoir level is highest or is rising most rapidly, and in fall, when the level is lowest. Both spring and fall quakes appear to be triggered by minor local stresses superposed on regional tectonic stresses; faulting is postulated to occur when the effective normal stress across a fault is decreased by a local increase in pore-fluid pressure. The spring quakes tend to occur when the reservoir level suddenly rises: increased pore pressure pushes apart the walls of the graben flooded by the reservoir, thus decreasing the effective normal stress across faults in the graben. The fall quakes tend to occur when reservoir level is lowest: water that gradually infiltrated poorly permeable (fault-gouge?) zones during high reservoir stands is then under anomalously high pressure, which decreases the effective normal stress across faults in the poorly permeable zones.
Study Area
Publication type | Report |
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Publication Subtype | USGS Numbered Series |
Title | A model for earthquakes near Palisades Reservoir, southeast Idaho |
Series title | Open-File Report |
Series number | 75-12 |
DOI | 10.3133/ofr7512 |
Year Published | 1975 |
Language | English |
Publisher | U.S. Geological Survey |
Description | i, 18 p. |
Country | United States |
State | Idaho |
Other Geospatial | Palisades Reservoir |
Google Analytic Metrics | Metrics page |