Volcano risk lunch - understanding volcano-seismic crises at volcanoes
Volcano-Seismic (V-S) crises: The slow passage from quiescence to eruption
If a V-S crisis accelerates rapidly, with corroborating precursors; then the decision to evacuate is a simple one to make and can be more a matter of time before the inevitable damage.
Not all volcanoes behave this way, Montserrat had several "false alarms" with V-S crises in 1897, 1933, 1966, 1985, 1992 and then the crisis that spiralled to eruption in 1995. Unzen followed a similar pattern with a more linear decline in repose between V-S crises, as did Mt. Spurr in Alaska but so too did the Southern centres of Dominica where only a phreatic eruption followed. Some volcanoes have V-S crises that are isolated and do not lead to eruption (e.g. Tenerife 2004), so are they totally stochastic events unrelated to the eventual eruption or part of a gradual process of building overpressure or plug degradation?
The idea is to have a short presentation (15 minutes) looking at some of the slow awakening volcanoes and the V-S crises they have had and to review some of the deterministic tools available.
Then have a discussion on the following...
a) How easy is it to determine a V-S crisis is none critical? (e.g. Tenerife 2004, Montserrat 1966-7)
b) Can we afford to evacuate populations on a "just in case" basis? (e.g. Guadeloupe 1976/7, Campi Flegrei 1970's and 1980's)
c) Is expert elicitation the solution?
Some good background reading will include:
Fiske, R.S., 1984, Volcanologists, journalists, and the concerned local public: A tale of two crises in the eastern Caribbean: in Studies in Geophysics Explosive Volcanism: Inception, Evolution and Hazards , National Academy Press, Washington, p. 170-176.
This is a nice short paper with some interesting observations of volcanic crisis management in practice, copies of this will be available from G10a (on my desk) from Friday afternoon if you have trouble getting hold of it.
Hopefully we will get to play an interesting thought game, "The Mayor of Naples", where we look at the options facing a mythical official faced with the ultimate decision on whether to evacuate the Bay of Naples area in the light of a slowly awakening Mt. Vesuvius.