Introduction to Fault Scarps

Overview of fault scarps, their evolution with time, and typcs.

1. Unit 3: Introduction to Fault Scarp A nalysis UNAVCO

2. Scarp morphology Modified from Wallace, 1977

3. Types of scarps Modified from Stewart and Hancock, 1990

4. Types of scarps Modified from Stewart and Hancock, 1990

5. Scarp morphological evolution Modified from Stewart and Hancock, 1990

6. Example scarps USGS, Chris Crosby Hebgen Lake (1959) Wasatch Fault (~1985) El Mayor- Cucapah (2010)

7. Profile extraction Chris Crosby

8. Example profile Indiana University Geologic Field Station

9. Rupture length – maximum displacement Modified from Wells and Coppersmith, 1994

10. 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)

11. 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

12. Variables: dx: spacing between measurements d t : time between each calculation step k: transport rate of sediment Israel: 0.1 m 2 / ka Basin and Range: 1 m 2 / ka California/Michigan: 10 m 2 / ka Use the given spreadsheet, variables above, and your profile to model hillslope diffusion. Hillslope diffusion