Normal-Fault Scarp and Footwall Uplift

Photo
Fault scarp produced during the 1983 Borah Peak earthquake on the Lost River normal fault, Idaho. The hanging-wall block is located on the right side of the fault; the footwall block is located on the left side of the fault. Note the mountains in the footwall block, which formed as the cumulative effect of multiple earthquake slip events, each of which uplifted the footwall block by a small event. The photo was taken in 1995, and shows that the scarp has degraded considerably since 1983 (see previous slide). The degree of degradation allows us to estimate the ages of paleo-fault scarps. Photo credit: Roy W. Schlische.