Ground Motions of the December 2015 M 4.7 Vancouver Island Earthquake: Attenuation and Site Response
Bibliographic record
Abstract
Research Article| September 26, 2017 Ground Motions of the December 2015 M 4.7 Vancouver Island Earthquake: Attenuation and Site Response Frederick Jackson; Frederick Jackson aDepartment of Earth Sciences, University of Western Ontario, 1151 Richmond St. N, London, Ontario, Canada N6A 5B7, smolnar8@uwo.ca Search for other works by this author on: GSW Google Scholar Sheri Molnar; Sheri Molnar aDepartment of Earth Sciences, University of Western Ontario, 1151 Richmond St. N, London, Ontario, Canada N6A 5B7, smolnar8@uwo.ca Search for other works by this author on: GSW Google Scholar Hadi Ghofrani; Hadi Ghofrani aDepartment of Earth Sciences, University of Western Ontario, 1151 Richmond St. N, London, Ontario, Canada N6A 5B7, smolnar8@uwo.ca Search for other works by this author on: GSW Google Scholar Gail M. Atkinson; Gail M. Atkinson aDepartment of Earth Sciences, University of Western Ontario, 1151 Richmond St. N, London, Ontario, Canada N6A 5B7, smolnar8@uwo.ca Search for other works by this author on: GSW Google Scholar John F. Cassidy; John F. Cassidy bNatural Resources Canada, Geological Survey of Canada, P.O. Box 6000, Sidney, British Columbia, Canada V8L 4B2 Search for other works by this author on: GSW Google Scholar Karen Assatourians Karen Assatourians aDepartment of Earth Sciences, University of Western Ontario, 1151 Richmond St. N, London, Ontario, Canada N6A 5B7, smolnar8@uwo.ca Search for other works by this author on: GSW Google Scholar Author and Article Information Frederick Jackson aDepartment of Earth Sciences, University of Western Ontario, 1151 Richmond St. N, London, Ontario, Canada N6A 5B7, smolnar8@uwo.ca Sheri Molnar aDepartment of Earth Sciences, University of Western Ontario, 1151 Richmond St. N, London, Ontario, Canada N6A 5B7, smolnar8@uwo.ca Hadi Ghofrani aDepartment of Earth Sciences, University of Western Ontario, 1151 Richmond St. N, London, Ontario, Canada N6A 5B7, smolnar8@uwo.ca Gail M. Atkinson aDepartment of Earth Sciences, University of Western Ontario, 1151 Richmond St. N, London, Ontario, Canada N6A 5B7, smolnar8@uwo.ca John F. Cassidy bNatural Resources Canada, Geological Survey of Canada, P.O. Box 6000, Sidney, British Columbia, Canada V8L 4B2 Karen Assatourians aDepartment of Earth Sciences, University of Western Ontario, 1151 Richmond St. N, London, Ontario, Canada N6A 5B7, smolnar8@uwo.ca Publisher: Seismological Society of America First Online: 27 Sep 2017 Online Issn: 1943-3573 Print Issn: 0037-1106 Bulletin of the Seismological Society of America (2017) 107 (6): 2903–2916. https://doi.org/10.1785/0120170071 Article history First Online: 27 Sep 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Frederick Jackson, Sheri Molnar, Hadi Ghofrani, Gail M. Atkinson, John F. Cassidy, Karen Assatourians; Ground Motions of the December 2015 M 4.7 Vancouver Island Earthquake: Attenuation and Site Response. Bulletin of the Seismological Society of America 2017;; 107 (6): 2903–2916. doi: https://doi.org/10.1785/0120170071 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search Abstract The December 2015 moment magnitude (M) 4.7 Vancouver Island earthquake is one of the largest recorded inslab earthquakes within Georgia Strait, British Columbia, Canada. Ground motions from all seismic stations within 500 km from the epicenter are examined. Peak ground acceleration reached a maximum of 4.65%g in Greater Victoria. We compare the observed horizontal‐component 5% damped pseudospectral acceleration (PSA) values with the inslab ground‐motion prediction equation (GMPE) suite used in the 2015 National Building Code of Canada (NBCC). PSA values from this event are significantly lower than the expected 2015 NBCC values for an M 4.7 inslab event, highlighting poor GMPE scaling at this low magnitude level. We develop an event‐specific GMPE to constrain the source and attenuation parameters in comparison with seismological models. Potential site effects are examined at strong‐motion stations within 85 km of the epicenter. High amplification at 4–6 Hz is observed on both thick sediment sites and on the northern edge of the Fraser delta, as observed in previous earthquakes. Gross generalizations of observed variable earthquake shaking are captured by current regional seismic microzonation maps; however, local discrepancies are present. This earthquake generated the first borehole array recordings obtained at depth in British Columbia. Recorded motions increase toward the surface and are of similar or higher amplitude than at nearby surface stations. Amplification between top and bottom sensors is a consistent factor of 7–8 in all three arrays over a similar 40–45‐m depth interval of Fraser delta sediments. Cross‐correlation analysis determines shear‐wave velocity estimates less than 350 m/s consistent with these delta sediments. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".