Reducing Exposure to Volcanic Hazards: The Role of Forecasts and Public Education, Study notes of Environmental Science

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Risk – probability of loss

(probable losses)

Risk = hazard (P7) x exposure (P8)

x vulnerability (P9)

(x value)

P(8)

Exposure, 0-1:

Chance that an individual or object

will be exposed to hazard

Exposure is a function of •

Quality, reliability of forecasts

• Volcanic hazards maps – Event (probability trees) – Specific forecasts, including VEI and eruption windows, AND

Public education about hazards (e.g., videos, interactivecomputer games), contingency (emergency) planning;AND

Appropriate responses by officials and by those at risk

• long-term land use planning; – short-term evacuations

Forecasts that are successful (or

not) in decreasing exposure

Successful:

• MSH, post 5/18/1980, 2004; Sakurajima, many – Redoubt, 1989; Kelut, 1990; Pinatubo 1991; – Popocatepetl 1994; Montserrat 1997

Partly successful:

• MSH 5/18/80; Tungurahua 1999 ff; Montserrat, 1995 – Rabaul, 1994 (after >11 y of precursor!); Miyakejima, 2000

Unsuccessful (missed or false alarm):

• Missed: El Chichon, 1982; Mayon, 1993; Nyiragongo, 2002 – False alarm: Soufriere Guadeloupe 1976; Akutan 1996 –

exposure reduced in the short term but increased in long-term?

Pending, or not quite ready for forecasts:

• Mauna Loa 2005; – Campi Flegrei, Long Valley

Public education successes (or not)

in reducing exposure

• Failures: Nevado del Ruiz 1985 • Successes: Pinatubo, 1991; Rabaul 1994 • Partial successes: Pinatubo lahars (post

91); Tungurahua 1999-present

• Pending: Rainier lahars; Long Valley

Other measures, cont) :

Long-range land use planning

• Wise land-use: MSH NVM; upper slopes

of Vesuvius

• Partial: Orting, at foot of Rainier (growth

allowed but only w/ new warning system)

• Too late for land use planning: Vulcano,

Campi Flegrei,

Napoli, Pompeii, Ercolano and Vesuvio.

Part of Campi Flegrei calderaand Pozzuoli visible at far left. It’salmost too late for land use plans,but houses closest to the volcano arebeing demolished and ownerscompensated.

CF

V

P

E

N

The ultimate test – using forecasts,

public education, and plans:

Short-term evacuations

Subject to pfs, evacuated vs. not evacuated.Pinatubo, Soufriere Hills (Montserrat) vs.Pompeii, St. Pierre, El Chichon

Subject to lahars, evacuated vs. not: Pinatuboor (Rainier) vs. Nevado del Ruiz (Armero)

Vesuvius and nearby towns will be a stiff test

For estimating exposure, here are

some rules of thumb…

• Full time resident, refuses to leave despite

warnings (Harry Truman case): 1.

• Full time worker, 8 h/day, 5 d/wk, if no

warnings or evacuation: 0.

• Tourist, 1d/y, if no warnings/evac: 0.003 • With warnings and evacuations, divide any

of the above by at least 10, in some casesby 100.