Group A, Poster #107, Earthquake Geology
Tectonic landform and lithologic age impact uncertainties in fault displacement hazard models
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Poster Presentation
2024 SCEC Annual Meeting, Poster #107, SCEC Contribution #13944 VIEW PDF
hologic age. We focus on the 1983 M6.9 Borah Peak, 2014 M6.0 Napa, 2016 M7.0 Kumamoto, and 2016 M7.8 Kaikoura earthquakes. These earthquakes collectively represent different slip senses, earthquake magnitudes, and climates.
We find that certain tectonic landforms, such as fault scarps and range fronts, identified before these earthquakes correlate with lower fault location errors and median displacements above displacement model predictions. Ruptures that lack tectonic landforms identified before the earthquakes have larger fault location error and accommodate displacements below model predictions. Faults cutting Holocene units exhibit the largest location errors, reflecting agricultural activity, anthropogenic development, and fluvial and other surface processes that erode, bury and/or alter fault evidence. The lower displacements in Holocene units may reflect that faults in younger units have recorded fewer earthquakes yet with more distributed deformation than faults in older units.
This study demonstrates that tectonic landforms and lithologic age significantly impact fault location uncertainty and coseismic displacement and should be considered in fault mapping and fault displacement assessment. In particular, tectonic landforms and surficial age correlate with the over or underprediction of fault displacement amplitude. For site-specific fault displacement assessments that rely on geomorphic mapping for fault location, consideration should be given to adjusting modelled fault displacements based on landforms, mapping confidence, and unit age. Additionally, our results are consistent with characteristic earthquake behavior in a general sense, suggesting that earthquakes may repeat slip at a point, thereby maintaining landforms indicative of faulting.
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We find that certain tectonic landforms, such as fault scarps and range fronts, identified before these earthquakes correlate with lower fault location errors and median displacements above displacement model predictions. Ruptures that lack tectonic landforms identified before the earthquakes have larger fault location error and accommodate displacements below model predictions. Faults cutting Holocene units exhibit the largest location errors, reflecting agricultural activity, anthropogenic development, and fluvial and other surface processes that erode, bury and/or alter fault evidence. The lower displacements in Holocene units may reflect that faults in younger units have recorded fewer earthquakes yet with more distributed deformation than faults in older units.
This study demonstrates that tectonic landforms and lithologic age significantly impact fault location uncertainty and coseismic displacement and should be considered in fault mapping and fault displacement assessment. In particular, tectonic landforms and surficial age correlate with the over or underprediction of fault displacement amplitude. For site-specific fault displacement assessments that rely on geomorphic mapping for fault location, consideration should be given to adjusting modelled fault displacements based on landforms, mapping confidence, and unit age. Additionally, our results are consistent with characteristic earthquake behavior in a general sense, suggesting that earthquakes may repeat slip at a point, thereby maintaining landforms indicative of faulting.
SHOW MORE
Citation: Scott, C. P., Kottke, A. R., Madugo, C. M., Arrowsmith, R., Adam, R. N., & Zuckerman, M. G. (2024, 09). Tectonic landform and lithologic age impact uncertainties in fault displacement hazard models. Poster Presentation at 2024 SCEC Annual Meeting.
Relevant SCEC Themes:
Applied Science Implementation
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