The Lifespan of Fault-Crossing Channels

Kelian Dascher-Cousineau, Noah Finnegan, & Emily E. Brodsky

Under Review 2021, SCEC Contribution #11001

Successive earthquakes drive landscape evolution. Yet the mechanism and pace with which landscapes respond remain poorly understood. Offset channels in the Carrizo Plain capture the fluvial response to lateral slip on the San Andreas Fault on millennial timescales. Here, we develop and test a model that quantifies competition between fault slip, which elongates channels, and aggradation, which causes channel infilling and, ultimately, abandonment. Validation of this model supports a transport-limited fluvial response and implies that measurements derived from present-day channel geometry are sufficient to quantify the relative rates of slip and bedload transport. Extension of the model identifies the threshold for which persistent change in transport capacity, obliquity in slip, or advected topography results in reorganization of the drainage network.

Dascher-Cousineau, K., Finnegan, N., & Brodsky, E. E. (2021). The Lifespan of Fault-Crossing Channels. Science, (under review).