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CoV 8. Managing Worst-Case Scenarios
From: Chris Newhall <cnewhall@xxxxxxxxxx>
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INVITATION TO CONTRIBUTE TO SESSION (3.I.F) of COV8, MANAGING WORST-CASE SCENARIOS
Every volcano has a range of “normal” behaviour and much less frequent, exceptional behaviour. Merapi normally produces small, VEI 1-3 eruptions, but occasionally produces a VEI 4 (e.g., 2010) or even a VEI 5 eruption. Mount St. Helens normally produces vertically-directed subplinian and plinian eruptions, and domes, but occasionally (as in 1980) produces a giant sector collapse and lateral blast. A combination of these two (with reference to Bandai 1888) was considered during precursory unrest at Mount St. Helens to be too unlikely to include in public warnings. Warnings at Mount Pinatubo’s in 1991 were intended to include the worst-case but we learned after that eruption that even worse events had occurred in the past. And exceptionally large eruptions (VEI 7 or larger), though infrequent, do occur.
Discussion of “worst-cases” raises some tough questions, e.g.,
o What can be considered a plausible “worst-case scenario?” Is it based just on hazard, or also on risk? Must there be a precedent for it at the specific volcano in question?
o How can these be presented, publicly, in proper context and without causing overreaction? What are the important steps in bringing the “worst-case scenario” to public attention?
o Under what circumstances would one recommend action based on a worst-case scenario – e.g., density of population, difficulty of evacuation, or unusual, diagnostic or highly uncertain monitoring signs?
o Can cost-benefit studies of mitigation be used for choosing whether and how to mitigate a worst-case scenario?
o How high must the probability be for a “worst-case” in order for it to be used as a basis for crisis response? Or, stated differently, what probability of eruption should be used for the crisis response?
o If evacuation for a worst-case scenario is called, how long should/could such an evacuation be sustained if the worst-case doesn’t materialize? How can evacuees be convinced to maintain a recommended evacuation?
o If evacuation is for a smaller eruption, but the possibility of a “worst-case” still remains, would one ever ramp up to response to “worst-case?” If yes, what could be a defensible basis for continuing the evacuation?
o Is there a scale of “worst-case” eruption that one simply can’t mitigate? i.e., a scale so large that it might be acknowledged but not considered in emergency plans? Who decides, and how?
Please share with us your experiences and thoughts about managing “worst-case” scenarios.
Conveners : Chris Newhall, Supriyati Andreastuti, Luis Lara, Mauro Rosi, and Gordon Woo
PLEASE NOTE: ABSTRACT DEADLINE HAS BEEN EXTENDED TO APRIL 30.
From: Chris Newhall <cnewhall@xxxxxxxxxx>
************************************************************************************************
INVITATION TO CONTRIBUTE TO SESSION (3.I.F) of COV8, MANAGING WORST-CASE SCENARIOS
Every volcano has a range of “normal” behaviour and much less frequent, exceptional behaviour. Merapi normally produces small, VEI 1-3 eruptions, but occasionally produces a VEI 4 (e.g., 2010) or even a VEI 5 eruption. Mount St. Helens normally produces vertically-directed subplinian and plinian eruptions, and domes, but occasionally (as in 1980) produces a giant sector collapse and lateral blast. A combination of these two (with reference to Bandai 1888) was considered during precursory unrest at Mount St. Helens to be too unlikely to include in public warnings. Warnings at Mount Pinatubo’s in 1991 were intended to include the worst-case but we learned after that eruption that even worse events had occurred in the past. And exceptionally large eruptions (VEI 7 or larger), though infrequent, do occur.
Discussion of “worst-cases” raises some tough questions, e.g.,
o What can be considered a plausible “worst-case scenario?” Is it based just on hazard, or also on risk? Must there be a precedent for it at the specific volcano in question?
o How can these be presented, publicly, in proper context and without causing overreaction? What are the important steps in bringing the “worst-case scenario” to public attention?
o Under what circumstances would one recommend action based on a worst-case scenario – e.g., density of population, difficulty of evacuation, or unusual, diagnostic or highly uncertain monitoring signs?
o Can cost-benefit studies of mitigation be used for choosing whether and how to mitigate a worst-case scenario?
o How high must the probability be for a “worst-case” in order for it to be used as a basis for crisis response? Or, stated differently, what probability of eruption should be used for the crisis response?
o If evacuation for a worst-case scenario is called, how long should/could such an evacuation be sustained if the worst-case doesn’t materialize? How can evacuees be convinced to maintain a recommended evacuation?
o If evacuation is for a smaller eruption, but the possibility of a “worst-case” still remains, would one ever ramp up to response to “worst-case?” If yes, what could be a defensible basis for continuing the evacuation?
o Is there a scale of “worst-case” eruption that one simply can’t mitigate? i.e., a scale so large that it might be acknowledged but not considered in emergency plans? Who decides, and how?
Please share with us your experiences and thoughts about managing “worst-case” scenarios.
Conveners : Chris Newhall, Supriyati Andreastuti, Luis Lara, Mauro Rosi, and Gordon Woo
PLEASE NOTE: ABSTRACT DEADLINE HAS BEEN EXTENDED TO APRIL 30.
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