Geomorphic evidence of earthquakes: linking mapper accuracy, landform degradation, and fragile geologic features

Malinda G. Zuckerman, Ramon Arrowsmith, Chelsea P. Scott, Alba M. Rodriguez Padilla, Christopher M. Madugo, & Albert R. Kottke

Submitted September 7, 2025, SCEC Contribution #14924, 2025 SCEC Annual Meeting Poster #TBD

Accurate assessment of earthquake ground motion and fault displacement hazard requires recognizing and interpreting geomorphic evidence of past earthquakes. We examine three factors that can affect the reliability and utility of tectonic landforms: (1) the preservation or erosion of surface rupture features, (2) the extent to which fragile geologic features capture strong ground motions, and (3) the interpretation of the preserved record by geoscientists. We synthesize three studies to characterize how natural variability in earthquake rupture and surface processes (aleatory variability), together with uncertainty from feature preservation and human interpretation (epistemic uncertainty), affect the recognition and use of geomorphic evidence for hazard assessment. First, landscape evolution modeling of post-earthquake topography shows that fault scarps and other landforms can lose 20–80% of their mappable length within 10 kyr, with the fastest degradation in the first few hundred years after rupture. Second, field observations and virtual shake table experiments of displaced rocks reveal insights into the intensity and distribution of near-field earthquake ground motions, extending hazard datasets into poorly instrumented regions. Third, a series of fault mapping projects demonstrates that mapped fault location accuracy varies with mapper experience, though less than expected. Together, these results show how earthquake rupture and surface processes interact to determine the preservation of geomorphic evidence, which shapes how geoscientists can observe and interpret the earthquake record over time. This research highlights the need for rapid, systematic documentation of surface rupture features and for hazard models that incorporate preservation limits and epistemic uncertainty in interpreting tectonic geomorphic evidence.

Key Words
tectonic geomorphology, fault scarp degradation, fragile geologic features, fault mapping

Citation
Zuckerman, M. G., Arrowsmith, R., Scott, C. P., Rodriguez Padilla, A. M., Madugo, C. M., & Kottke, A. R. (2025, 09). Geomorphic evidence of earthquakes: linking mapper accuracy, landform degradation, and fragile geologic features. Poster Presentation at 2025 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Geology