Probabilities of significant earthquake shaking in communities across British Columbia: implications for emergency management
Bibliographic record
Abstract
Seismic hazard in the province of British Columbia (BC) is well studied and extensively discussed within scientific and engineering communities. However, much of the information is presented in a forum or format not readily accessible or digestible by those outside the scientific and engineering communities, including individuals, elected officials, municipal planners, and emergency managers. Seismic hazard calculations were carried out for over 150 BC communities in terms of probabilities of exceeding each of three intensity levels (MMI V - widely felt; MMI VI - threshold for non-structural damage; and, MMI VII - threshold of structural damage) over 10, 50 and 100 year periods. This paper presents a subset of these calculations for 10 communities. The dominant tectonic feature in southwestern BC, where most of the BC population is concentrated, is the Cascadia Subduction Zone. Here, the Juan de Fuca plate is being forced beneath the North America plate, creating three distinct types of earthquakes: shallow (crustal) earthquakes within the North America plate, deep (subcrustal) earthquakes within the Juan de Fuca plate, and "megathrust" earthquakes at the interface of the two plates. Calculations for all earthquakes except those at the Cascadia subduction interface are based on the probabilistic seismic hazard models developed by the Geological Survey of Canada and adopted in the National Building Code of Canada. The probabilities of "structurally" damaging ground shaking due to crustal or subcrustal earthquakes occurring within the next 50 years in the two largest cities of BC, Vancouver and Victoria, are 12% and 21%, respectively. The corresponding probabilities of "non-structurally" damaging ground shaking are 35% and 56%, respectively. The subduction interface earthquake is considered separately using a timedependent recurrence model. The probability of the next Cascadia subduction interface earthquake occurring in the next 50 years is estimated to be 11%. The uncertainties associated with the probability estimations are discussed and quantified by providing upper and lower boundaries for selected calculations. Results presented in this paper are intended to enable individuals and community decision makers to better identify and understand the earthquake threat in their communities. This information is offered to encourage and facilitate informed discussion on earthquake threat in BC, and enable reasoned, defendable funding decisions with respect to emergency preparedness, response, and recovery activities.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.008 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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 source (direct Gemma or distilled Codex), 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".