Stream channel offsets along strike-slip faults: Interaction between fault slip and surface processes
Abstract
Stream-channel offset is a geomorphologic marker widely used to identify strike-slip faults and estimate fault slip rates, assuming that the offset is generated by fault slip. However, surface processes can modify and change stream channels offsets. Here we used a simple numerical model to study stream channel morphological evolution due to strike-slip fault slips and surface processes. Our results show competing effects: while fault slips offset stream channels, surface processes generally tend to straighten channels and shorten or obliterate offsets. Small fault offsets (a few meters) can be reconnected and straightened by new channels in a few hundred years or less. Over a longer time, the cumulative effects of repeated fault slips and surface processes can result in oblique and bent stream channels across the fault trace. The morphological evidence of fault-offsets would be better preserved when each fault slip is smaller and the fault zone is weaker. On the other hand, long recurrence intervals of slip events, irregular initial landforms, and complications of stream channel development such as stream capture, could further modify the morphological evidence of fault offsets. We systematically examined the effects of major factors, including the recurrence interval of fault slip, diffusion and incision coefficient, and time-dependent variations of the incision. Our results call for careful studies of surface processes when using stream-channel offset to infer fault slips and estimate slip rates.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.T45D0254L