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- Title
Tectonic Landform and Lithologic Age Impact Uncertainties in Fault Displacement Hazard Models.
- Authors
Scott, Chelsea; Kottke, Albert; Madugo, Christopher; Arrowsmith, J. Ramon; Adam, Rachel; Zuckerman, Malinda
- Abstract
Tectonic landforms and surficial lithologic age are essential data for producing quality late Quaternary fault maps and predicting coseismic fault rupture location before an earthquake. However, we lack a clear understanding of the relationship between tectonic landforms and shallow earthquake processes and how lithologic age relates to landform preservation. We assess how fault location error (rupture‐to‐fault separation distance) and coseismic displacement residual (difference between observed and predicted coseismic displacement) vary with tectonic landform and lithologic age for four historical earthquakes. Certain tectonic landforms identified before these earthquakes correlate with lower fault location errors and median displacements below model predictions. Faults cutting Holocene units exhibit the largest location errors, reflecting surface processes that erode or bury fault evidence. This study shows that tectonic landforms and lithologic age have a significant impact on fault location uncertainty and coseismic displacement, which should be considered in fault mapping and fault displacement assessment. Plain Language Summary: Accurate maps of tectonic faults are essential for a variety of purposes including assessing seismic hazard, studying faults, and planning land‐use. These fault maps typically rely on identifying features in the landscape formed by past earthquakes. Remote sensing data sets like imagery and elevation support this process. However, a major challenge in fault mapping is figuring out how to best interpret what the landforms indicate about faulting. In this study, we analyzed how confident we are about the location of faults mapped before four historical earthquakes. We found that faults indicated by prominent landforms better indicate where subsequent earthquake ruptures will occur relative to faults indicated by less noticeable landforms. We also show that fault mapping in Holocene units (representing the most recent geologic time‐period) with meter‐scale remote sensing data is particularly challenging. Our findings support making better informed fault maps based on a deeper understating of how clues in the landscape connect to faulting processes. Key Points: Fault trace mapping is informed by tectonic landforms and surficial geologyUncertainty in fault location and predicted coseismic displacements correlate with tectonic landform type and lithologic ageFaults indicated by prominent tectonic landforms have relatively low fault location error and accommodate high displacement
- Subjects
TECTONIC landforms; FAULT location (Engineering); LANDFORMS; EARTHQUAKES; SEISMIC event location; SURFACE fault ruptures
- Publication
Geophysical Research Letters, 2024, Vol 51, Issue 16, p1
- ISSN
0094-8276
- Publication type
Article
- DOI
10.1029/2024GL109145