A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis
A new history of great earthquakes (and their tsunamis) for the central and southern Cascadia subduction zone shows more frequent (17 in the past 6700 yr) megathrust ruptures than previous coastal chronologies. The history is based on along-strike correlations of Bayesian age models derived from eva...
| Main Authors: | , , , , , , , , , |
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| Format: | Journal Article |
| Language: | English |
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2022
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| Online Access: | https://hdl.handle.net/10356/157206 |
| _version_ | 1811684450908504064 |
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| author | Nelson, Alan R. DuRoss, Christopher B. Witter, Robert C. Kelsey, Harvey M. Engelhart, Simon E. Mahan, Shannon A. Gray, Harrison J. Hawkes, Andrea D. Horton, Benjamin Peter Padgett, Jason S. |
| author2 | Asian School of the Environment |
| author_facet | Asian School of the Environment Nelson, Alan R. DuRoss, Christopher B. Witter, Robert C. Kelsey, Harvey M. Engelhart, Simon E. Mahan, Shannon A. Gray, Harrison J. Hawkes, Andrea D. Horton, Benjamin Peter Padgett, Jason S. |
| author_sort | Nelson, Alan R. |
| collection | NTU |
| description | A new history of great earthquakes (and their tsunamis) for the central and southern Cascadia subduction zone shows more frequent (17 in the past 6700 yr) megathrust ruptures than previous coastal chronologies. The history is based on along-strike correlations of Bayesian age models derived from evaluation of 554 radiocarbon ages that date earthquake evidence at 14 coastal sites. We reconstruct a history that accounts for all dated stratigraphic evidence with the fewest possible ruptures by evaluating the sequence of age models for earthquake or tsunami contacts at each site, comparing the degree of temporal overlap of correlated site age models, considering evidence for closely spaced earthquakes at four sites, and hypothesizing only maximum-length megathrust ruptures. For the past 6700 yr, recurrence for all earthquakes is 370–420 yr. But correlations suggest that ruptures at ∼1.5 ka and ∼1.1 ka were of limited extent (<400 km). If so, post-3-ka recurrence for ruptures extending throughout central and southern Cascadia is 510–540 yr. But the range in the times between earthquakes is large: two instances may be ∼50 yr, whereas the longest are ∼550 and ∼850 yr. The closely spaced ruptures about 1.6 ka may illustrate a pattern common at subduction zones of a long gap ending with a great earthquake rupturing much of the subduction zone, shortly followed by a rupture of more limited extent. The ruptures of limited extent support the continued inclusion of magnitude-8 earthquakes, with longer ruptures near magnitude 9, in assessments of seismic hazard in the region. |
| first_indexed | 2024-10-01T04:28:50Z |
| format | Journal Article |
| id | ntu-10356/157206 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T04:28:50Z |
| publishDate | 2022 |
| record_format | dspace |
| spelling | ntu-10356/1572062022-05-14T20:11:20Z A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis Nelson, Alan R. DuRoss, Christopher B. Witter, Robert C. Kelsey, Harvey M. Engelhart, Simon E. Mahan, Shannon A. Gray, Harrison J. Hawkes, Andrea D. Horton, Benjamin Peter Padgett, Jason S. Asian School of the Environment Earth Observatory of Singapore Science::Geology Megathrust Earthquake Tsunamis Cascadia Rupture Model A new history of great earthquakes (and their tsunamis) for the central and southern Cascadia subduction zone shows more frequent (17 in the past 6700 yr) megathrust ruptures than previous coastal chronologies. The history is based on along-strike correlations of Bayesian age models derived from evaluation of 554 radiocarbon ages that date earthquake evidence at 14 coastal sites. We reconstruct a history that accounts for all dated stratigraphic evidence with the fewest possible ruptures by evaluating the sequence of age models for earthquake or tsunami contacts at each site, comparing the degree of temporal overlap of correlated site age models, considering evidence for closely spaced earthquakes at four sites, and hypothesizing only maximum-length megathrust ruptures. For the past 6700 yr, recurrence for all earthquakes is 370–420 yr. But correlations suggest that ruptures at ∼1.5 ka and ∼1.1 ka were of limited extent (<400 km). If so, post-3-ka recurrence for ruptures extending throughout central and southern Cascadia is 510–540 yr. But the range in the times between earthquakes is large: two instances may be ∼50 yr, whereas the longest are ∼550 and ∼850 yr. The closely spaced ruptures about 1.6 ka may illustrate a pattern common at subduction zones of a long gap ending with a great earthquake rupturing much of the subduction zone, shortly followed by a rupture of more limited extent. The ruptures of limited extent support the continued inclusion of magnitude-8 earthquakes, with longer ruptures near magnitude 9, in assessments of seismic hazard in the region. Ministry of Education (MOE) National Research Foundation (NRF) Published version This work was supported by the Earthquake Hazards Program of the U.S. Geological Survey and by U.S. National Science Foundation Awards EAR-1419824 to Horton, EAR-1419844 to Engelhart, and EAR-9405263 to Kelsey. Kelsey, Witter, Engelhart, and Padgett were also funded by the National Earthquake Hazards Reduction Pro- gram of the U.S. Geological Survey (Award Numbers 02HQGR0056, 02HQGR0057, G14AP00128, G14AP00129, G17AP00028, G19AP00105, and 1434-93-G-2321). Horton’s research was sup- ported by the Earth Observatory of Singapore via its funding from the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centres of Excellence initiative. Horton was additionally funded by the Singapore Min- istry of Education Academic Research Fund (MOE2019-T3-1-004 and MOE2018-T2-1-030). The National Ocean Sciences Accelerator Mass Spectrometry facility (NOSAMS) at Woods Hole Oceanographic Institution (WHOI) supported the analysis of five 14C AMS samples during Hawkes’ WHOI NOSAMS postdoctoral fellowship. Able field and laboratory assistance was provided by Rich Briggs, Lee Ann Bradley, Zeb Maharrey (all with U.S. Geological Survey, Golden, Colorado), Andy Grand Pre (University of Penn- sylvania), and SeanPaul La Selle (U.S. Geological Survey, Santa Cruz, California). This manuscript was improved through reviews by Lisa Ely (Central Washington University, Ellensburg, Washington), Kate Clark (GNS Science, Lower Hutt, New Zealand), Chris Goldfinger (Oregon State University, Corvallis, Oregon), and an anonymous reviewer. This work comprises Earth Observatory of Singapore contribution number 355. 2022-05-10T06:48:44Z 2022-05-10T06:48:44Z 2021 Journal Article Nelson, A. R., DuRoss, C. B., Witter, R. C., Kelsey, H. M., Engelhart, S. E., Mahan, S. A., Gray, H. J., Hawkes, A. D., Horton, B. P. & Padgett, J. S. (2021). A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis. Quaternary Science Reviews, 261, 106922-. https://dx.doi.org/10.1016/j.quascirev.2021.106922 0277-3791 https://hdl.handle.net/10356/157206 10.1016/j.quascirev.2021.106922 2-s2.0-85105692483 261 106922 en MOE2019-T3-1-004 MOE2018-T2-1-030 Quaternary Science Reviews © 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). application/pdf |
| spellingShingle | Science::Geology Megathrust Earthquake Tsunamis Cascadia Rupture Model Nelson, Alan R. DuRoss, Christopher B. Witter, Robert C. Kelsey, Harvey M. Engelhart, Simon E. Mahan, Shannon A. Gray, Harrison J. Hawkes, Andrea D. Horton, Benjamin Peter Padgett, Jason S. A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis |
| title | A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis |
| title_full | A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis |
| title_fullStr | A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis |
| title_full_unstemmed | A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis |
| title_short | A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis |
| title_sort | maximum rupture model for the central and southern cascadia subduction zone reassessing ages for coastal evidence of megathrust earthquakes and tsunamis |
| topic | Science::Geology Megathrust Earthquake Tsunamis Cascadia Rupture Model |
| url | https://hdl.handle.net/10356/157206 |
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