Group A, Poster #111, Earthquake Geology
Development of the Geomorphic Indicator Ranking System for pre-rupture fault mapping
Poster Image:
Poster Presentation
2022 SCEC Annual Meeting, Poster #111, SCEC Contribution #12521 VIEW PDF
in the landscape and reduce epistemic uncertainty in desktop-based fault mapping. Geomorphic features receive a quantitative ‘score’ that ranges from 1 - 4 depending on the geomorphic strength for a fault (triangular facets and scarps are more indicative of faulting than lineaments). These features help the mapper place a certainty level (strong, distinct, weak, uncertain) on the mapped fault traces. We model our approach after Scharer et al. (2007) who assigned paleo-earthquake likelihood based on a systematic grading of the quality of the paleoseismic evidence.
We tested the GIR tool with student mappers in a pre-rupture fault mapping course co-taught by Arizona State University and University of Nevada, Reno in Spring 2022. After the course concluded, a group of professional geologists completed fault maps using the same approach. Our goal is to determine whether the GIR can be an effective framework to document the evidence that supports pre-rupture fault trace maps and to make the maps more consistent across mappers of different experience levels.
Further work includes comparing the final confidence ranking for the mapped fault traces determined strictly by the scaled GIR score versus the mapper’s geologic intuition. Meaning, the confidence ranking for a fault trace segment will differ depending on whether the mapper uses their best judgment to assign a confidence ranking or they use the quantitative approach (where the scores for the GIR features are counted and scaled to a 1-4 score that corresponds with fault confidence strength). This analysis will inform the efficacy of using the GIR, the discrepancies between the quantitative and qualitative approach to the mapping, and determine which geomorphic features indicate active faulting better than other features.
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We tested the GIR tool with student mappers in a pre-rupture fault mapping course co-taught by Arizona State University and University of Nevada, Reno in Spring 2022. After the course concluded, a group of professional geologists completed fault maps using the same approach. Our goal is to determine whether the GIR can be an effective framework to document the evidence that supports pre-rupture fault trace maps and to make the maps more consistent across mappers of different experience levels.
Further work includes comparing the final confidence ranking for the mapped fault traces determined strictly by the scaled GIR score versus the mapper’s geologic intuition. Meaning, the confidence ranking for a fault trace segment will differ depending on whether the mapper uses their best judgment to assign a confidence ranking or they use the quantitative approach (where the scores for the GIR features are counted and scaled to a 1-4 score that corresponds with fault confidence strength). This analysis will inform the efficacy of using the GIR, the discrepancies between the quantitative and qualitative approach to the mapping, and determine which geomorphic features indicate active faulting better than other features.
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Citation: Adam, R. N., Scott, C. P., Arrowsmith, R., Zuckerman, M. G., Madugo, C. M., Koehler, R. D., Reano, D., & Kozaci, O. (2022, 09). Development of the Geomorphic Indicator Ranking System for pre-rupture fault mapping. Poster Presentation at 2022 SCEC Annual Meeting.
Keywords: Probabilistic Fault Displacement Hazard Assessment, Geomorphic Indicator Ranking
Relevant SCEC Themes:
Probabilistic Seismic Hazard Analysis
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