Titill: | Contemporary tectonics of the Wasatch front region, Utah, from earthquake focal mechanisms |
Höfundur: |
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Útgáfa: | 1989 |
Tungumál: | Enska |
Umfang: | 731-755 |
Háskóli/Stofnun: | Háskóli Íslands University of Iceland |
Svið: | Verkfræði- og náttúruvísindasvið (HÍ) School of Engineering and Natural Sciences (UI) |
Deild: | Raunvísindastofnun (HÍ) Science Institute (UI) |
Birtist í: | Bulletin of the Seismological Society of America;79(3) |
ISSN: | 0037-1106 |
Efnisorð: | Jarðskjálftar; Jarðskjálftamælingar; Misgengi (jarðfræði); Utah |
URI: | https://hdl.handle.net/20.500.11815/571 |
Tilvitnun:Ingi Þorleifur Bjarnason, James C. Pechmann. (1989). Contemporary tectonics of the Wasatch front region, Utah, from earthquake focal mechanisms. Bulletin of the Seismological Society of America, 79(3), 731-755.
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Útdráttur:We have completed a comprehensive study of focal mechanisms of digitally
recorded earthquakes (M, -_< 4.4) that occurred in the Wasatch front region in
Utah during 1980 to 1986. Single-event solutions for 24 events were determined
using recently revised crustal models and a computerized grid-search technique.
Overall, the mechanisms show predominantly normal faulting on N-S-striking
nodal planes of moderate to steep dip (>30°). Tension-axis azimuths average
96 ° _+ 12% Thus, in general, the mechanisms indicate E-W to ESE-WNW crustal
extension and vertical crustal shortening. Oblique slip, when observed, is characterized
by left-lateral motion on planes striking N to NE or right-lateral motion
on planes striking N to NW. Most of the mechanisms with significant amounts of
oblique-slip motion occur in the southern part of the study area, where compression-
axis orientations range from near vertical to near horizontal. Thus, the
mechanisms suggest a possible change in stress regime from north to south
along the Wasatch front. Despite geologic evidence for low-angle faults in the
study area, shallowly dipping nodal planes are relatively uncommon.
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