introduction to fault scarps
TRANSCRIPT
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Unit 3: Introduction to
Fault Scarp Analysis
UNAVCO
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Scarp morphology
Modified from Wallace, 1977
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Types of scarps
Modified from Stewart and Hancock, 1990
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Types of scarps
Modified from Stewart and Hancock, 1990
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Scarp morphological evolution
Modified from Stewart and Hancock, 1990
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Example scarps
USGS, Chris Crosby
Hebgen Lake (1959) Wasatch Fault (~1985)
El Mayor-Cucapah (2010)
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Profile extraction
Chris Crosby
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Example profile
Indiana University Geologic Field Station
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Rupture length – maximum displacement
Modified from Wells and Coppersmith, 1994
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Rupture length – magnitude
Relationship between displacement length and earthquake magnitude M = Magnitude L = Length
All rupture types M = 5.08+1.16*log(L)
Strike slip rupture M = 5.16+1.12*log(L)
Reverse or thrust rupture M = 5.00+1.22*log(L)
Normal rupture M = 4.86+1.32*log(L)
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• Variables: fault scarp eroded material height, m (H) erosion rate, m/yr (ER) Recurrence interval, yr (RI)
• H / ER = RI• Use many estimated erosion rates to find
a recurrence interval that seems representative
Recurrence interval
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• Variables: dx: spacing between measurements dt: time between each calculation step k: transport rate of sediment
• Israel: 0.1 m2/ka• Basin and Range: 1 m2/ka• California/Michigan: 10 m2/ka
• Use the given spreadsheet, variables above, and your profile to model hillslope diffusion.
Hillslope diffusion