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Avalanche Danger Scale North American Development Work

Avalanche Danger Scale North American Development Work. Grant Statham, Mountain Risk Specialist. Since 2005 with the United States. Who is it for? What comprises avalanche danger? What process is used in analysis?. The Problem with the Avalanche Danger Scale. CONSEQUENCE is absent

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Avalanche Danger Scale North American Development Work

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  1. Avalanche Danger Scale North American Development Work Grant Statham, Mountain Risk Specialist

  2. Since 2005 with the United States • Who is it for? • What comprises avalanche danger? • What process is used in analysis?

  3. The Problem with the Avalanche Danger Scale • CONSEQUENCE is absent • PROBABILITY terms are vague • MITIGATION advice is weak

  4. CONCLUSION . . . • It is a poor evaluation and communication tool for both professionals and the public • Our forecasting and communication systems do not fit within a modern risk framework The problem is not just the danger scale, but also the theory behind it

  5. We require • Technical model for avalanche forecasting • (based on RISK THEORY) 2. Communication model for public bulletins (based on the TECHNICAL MODEL and FOCUS TESTED)

  6. RISK THEORY AVALANCHE HAZARD Probability Consequence

  7. SNOW STABILTY RATING SYSTEM CAA, 2002 OGRS

  8. Stability vs. Danger Feb 8 - 11, 2006 Selkirk Mountains, BC

  9. Avalanche Activity: The latest report of a large deep slab avalanche was a size 4.0 from the north face of Sifton that fractured 2-3m deep, 300m wide and ran on glacial ice. This avalanche ran full path for 2 km including 500m over flat terrain. STABILITY Fair Good Good DANGER Considerable Considerable Moderate

  10. Stability and Terrain Choices COAST Good Good Good

  11. Stability and Terrain Choices ROCKIES Good Good Good

  12. Terrain list – February 2003 Roger Atkins, 2004

  13. Terrain list – February 2004 Roger Atkins, 2004

  14. So where do we account for consequence? • Professionals = Intuitive and discussion based • Public = Buried inside lengthy text messages

  15. What represents consequence? • Avalanche size • Avalanche character

  16. AVALANCHE HAZARD Probability Consequence

  17. Lets start from the foundations of avalanche forecasting Decomposition

  18. AVALANCHE HAZARD Probability Consequence

  19. AVALANCHE HAZARD Probability Consequence

  20. AVALANCHE HAZARD Probability Consequence

  21. Foundations FORECASTING ACTIVITY SCALE CONFIDENCE AVALANCHES SNOWPACK TERRAIN WEATHER

  22. Cognitive, Inductive Reasoning FORECASTING ACTIVITY SCALE CONFIDENCE AVALANCHES SNOWPACK TERRAIN WEATHER

  23. Sensitivity to Triggering AVALANCHE HAZARD Probability Spatial Distribution Consequence

  24. Discrete choices necessary (subjective probability assessment) Sensitivity to Triggering AVALANCHE HAZARD Probability Spatial Distribution Consequence Avalanche Size Avalanche Character

  25. AVALANCHE HAZARD Likelihood of Triggering Destructive Potential

  26. CONFIDENCE • Degree: Low → High • Factors: • Anomalies • Unusual events • Unprecedented events or conditions • Amount of data • Quality of data • Spatial scale • Temporal scale • Spatial variability • Temporal variability • Lingering instability • State of knowledge • Forecaster’s experience levels

  27. Avalanche Hazard Sensitivity to Triggering Triggering Likelihood Spatial Distribution Destructive Potential Size Character Confidence

  28. Avalanche Hazard Sensitivity to Triggering Triggering Likelihood Spatial Distribution Destructive Potential Size Character Conclusion (activity specific) Confidence Avalanche danger rating is only a conclusion

  29. Conclusion and Communication 5 - EXTREME 4 -HIGH 3 -CONSIDERABLE Likelihood of Triggering 2 - MODERATE 1 - LOW Destructive Potential

  30. RISK THEORY Probability x Consequencex Exposure =RISK

  31. AVALANCHE RISK THEORY Likelihood of Triggering x Destructive Potential Avalanche Hazard (danger scale)

  32. AVALANCHE RISK THEORY Likelihood of Triggering x Destructive Potentialx Exposure = RISK Avalanche Hazard (danger scale)

  33. Public understanding requires more than just a conclusion

  34. Public understanding of avalanche danger requires • Better methods of describing forecasting processes • Use of RISK THEORY as a framework for avalanche forecasting • Consistent understanding and application by professionals • Basis for public education and communication Danger levels are only a communication strategy

  35. THANKYOU! Roger Atkins Clair Israelson Greg Johnson Brad White Bruce McMahon Karl Birkeland Janet Kallem Doug Abromeit Knox Williams Ethan Green Larry Stanier Chris Stethem John Kelly Ilya Storm Bruce Tremper Mark Moore Susan Hairsine Pascal Haegeli Alan Jones John Kelly

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