STEPS: Slip Time Earthquake Path Simulations Applied to the San Andreas and Toe Jam Hill Faults to Redefine Geologic Slip Rate Uncertainty
Abstract Geologic slip rates are a time‐averaged measurement of fault displacement calculated over hundreds to million‐year time scales and are a primary input for probabilistic seismic hazard analyses, which forecast expected ground shaking in future earthquakes. Despite their utility for seismic h...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2021-10-01
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| Series: | Geochemistry, Geophysics, Geosystems |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2021GC009848 |
| _version_ | 1797638089742483456 |
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| author | Alexandra E. Hatem Ryan D. Gold Richard W. Briggs Katherine M. Scharer Edward H. Field |
| author_facet | Alexandra E. Hatem Ryan D. Gold Richard W. Briggs Katherine M. Scharer Edward H. Field |
| author_sort | Alexandra E. Hatem |
| collection | DOAJ |
| description | Abstract Geologic slip rates are a time‐averaged measurement of fault displacement calculated over hundreds to million‐year time scales and are a primary input for probabilistic seismic hazard analyses, which forecast expected ground shaking in future earthquakes. Despite their utility for seismic hazard calculations, longer‐term geologic slip rates represent a time‐averaged measure of the tempo of strain release and do not measure variability across earthquake cycles. We have developed a numerical approach called STEPS (Slip Time Earthquake Path Simulations), which is built upon field‐based observations and explicitly incorporates realistic variations in displacement per event and variability in the recurrence interval between earthquakes. The STEPS approach, which simulates strain release through time, relies on representing earthquake cycles as stairsteps, rather than straight‐line paths, connecting per earthquake time‐displacement coordinates. We simulate earthquake histories based on these input constraints using two examples: the Carrizo section of the San Andreas fault and the Toe Jam Hill fault of the Seattle fault zone. We find that modeled slip rate distributions agree with slip rates reported for the sites of interest by the original investigators, while providing a slip rate distribution that reflects the variability of earthquake frequency and displacement. The STEPS approach provides an estimate of fault slip rate uncertainty based on a synthetic suite of plausible time‐displacement paths resulting from individual earthquakes, rather than measurement uncertainties associated with offset features. When considering this simulated earthquake behavior between measurements, the uncertainty associated with earthquake paths is greater than that calculated by the long‐term rate. |
| first_indexed | 2024-03-11T12:57:38Z |
| format | Article |
| id | doaj.art-8605f6b02b5a49d9a211ce8d90580448 |
| institution | Directory Open Access Journal |
| issn | 1525-2027 |
| language | English |
| last_indexed | 2024-03-11T12:57:38Z |
| publishDate | 2021-10-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj.art-8605f6b02b5a49d9a211ce8d905804482023-11-03T16:56:09ZengWileyGeochemistry, Geophysics, Geosystems1525-20272021-10-012210n/an/a10.1029/2021GC009848STEPS: Slip Time Earthquake Path Simulations Applied to the San Andreas and Toe Jam Hill Faults to Redefine Geologic Slip Rate UncertaintyAlexandra E. Hatem0Ryan D. Gold1Richard W. Briggs2Katherine M. Scharer3Edward H. Field4U.S. Geological Survey Geologic Hazards Science Center Golden CO USAU.S. Geological Survey Geologic Hazards Science Center Golden CO USAU.S. Geological Survey Geologic Hazards Science Center Golden CO USAU.S. Geological Survey Earthquake Science Center Pasadena CA USAU.S. Geological Survey Geologic Hazards Science Center Golden CO USAAbstract Geologic slip rates are a time‐averaged measurement of fault displacement calculated over hundreds to million‐year time scales and are a primary input for probabilistic seismic hazard analyses, which forecast expected ground shaking in future earthquakes. Despite their utility for seismic hazard calculations, longer‐term geologic slip rates represent a time‐averaged measure of the tempo of strain release and do not measure variability across earthquake cycles. We have developed a numerical approach called STEPS (Slip Time Earthquake Path Simulations), which is built upon field‐based observations and explicitly incorporates realistic variations in displacement per event and variability in the recurrence interval between earthquakes. The STEPS approach, which simulates strain release through time, relies on representing earthquake cycles as stairsteps, rather than straight‐line paths, connecting per earthquake time‐displacement coordinates. We simulate earthquake histories based on these input constraints using two examples: the Carrizo section of the San Andreas fault and the Toe Jam Hill fault of the Seattle fault zone. We find that modeled slip rate distributions agree with slip rates reported for the sites of interest by the original investigators, while providing a slip rate distribution that reflects the variability of earthquake frequency and displacement. The STEPS approach provides an estimate of fault slip rate uncertainty based on a synthetic suite of plausible time‐displacement paths resulting from individual earthquakes, rather than measurement uncertainties associated with offset features. When considering this simulated earthquake behavior between measurements, the uncertainty associated with earthquake paths is greater than that calculated by the long‐term rate.https://doi.org/10.1029/2021GC009848geologic slip ratesseismic hazarduncertaintyearthquake cycleSan Andreas faultToe Jam Hill fault |
| spellingShingle | Alexandra E. Hatem Ryan D. Gold Richard W. Briggs Katherine M. Scharer Edward H. Field STEPS: Slip Time Earthquake Path Simulations Applied to the San Andreas and Toe Jam Hill Faults to Redefine Geologic Slip Rate Uncertainty Geochemistry, Geophysics, Geosystems geologic slip rates seismic hazard uncertainty earthquake cycle San Andreas fault Toe Jam Hill fault |
| title | STEPS: Slip Time Earthquake Path Simulations Applied to the San Andreas and Toe Jam Hill Faults to Redefine Geologic Slip Rate Uncertainty |
| title_full | STEPS: Slip Time Earthquake Path Simulations Applied to the San Andreas and Toe Jam Hill Faults to Redefine Geologic Slip Rate Uncertainty |
| title_fullStr | STEPS: Slip Time Earthquake Path Simulations Applied to the San Andreas and Toe Jam Hill Faults to Redefine Geologic Slip Rate Uncertainty |
| title_full_unstemmed | STEPS: Slip Time Earthquake Path Simulations Applied to the San Andreas and Toe Jam Hill Faults to Redefine Geologic Slip Rate Uncertainty |
| title_short | STEPS: Slip Time Earthquake Path Simulations Applied to the San Andreas and Toe Jam Hill Faults to Redefine Geologic Slip Rate Uncertainty |
| title_sort | steps slip time earthquake path simulations applied to the san andreas and toe jam hill faults to redefine geologic slip rate uncertainty |
| topic | geologic slip rates seismic hazard uncertainty earthquake cycle San Andreas fault Toe Jam Hill fault |
| url | https://doi.org/10.1029/2021GC009848 |
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