Transcript Document

Real time volcanic hazard evaluation during a
volcanic crisis: BET_EF and the MESIMEX
experiment
W. Marzocchi1, L. Sandri1, J. Selva1, G. Woo2
1- INGV-Bologna
2- Risk Management Solution
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Funded by INGV/DPC V4 and V3_4 Ve
OUTLINE of the presentation
BET and Eruption Forecasting
Cost/benefit analysis
MESIMEX application
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Why and how probabilities
Basic idea about how to use probabilities
Checking how BET works
BET and Eruption Forecasting
what we are estimating here…
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BET and Eruption Forecasting
BET_EF Package
Target volcano
Hazard procedure
OUTPUT
Event selection
(Unrest + Magmatic Intrusion + Eruption+Vent all locs + SIZE=2+)
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BET and Eruption Forecasting
Selection done: (1) unrest -> (2) magmatic intrusion -> (3) eruption -> (4) location all -> (5) SIZE=4+
ABSOLUTE PROBABILITY
Probability that all the events in the
selected path occur contemporaneously
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CONDITIONAL PROBABILITY AT
THE NODE
Probability that the events at the selected
node occur, given previous nodes
BET_EF IS DISTRIBUTED FOR FREE
A dedicated workshop will be held
JULY 12, Room 16, Acad. of fine ARTS
17:30 - 20:30 (food and drinks available!)
Marzocchi et al., JGR, 2004.
Marzocchi et al., IAVCEI, Statistics in Volcanology, 2006.
Marzocchi et al., Bull. Volc., 2007, in press.
Marzocchi and Woo, in prep.
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Cost/Benefit analysis
Some useful considerations…
 “Eruption forecasting” means to estimate probabilities
 Typical requirement from end-users: YES or NOT (but the
Nature seems not to much interested in playing
deterministically)
 How to interpret and to use probabilities? COMPARING
THEM WITH MORE USUAL EVENTS
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Cost/Benefit analysis
Let’s make the example of an evacuation (SIMPLIFIED!!!)
L: cost of human lives lost due to an eruption
C: cost of an evacuation
P: prob. of the deadly event (i.e., prob. of a pyroclastic flow)
If
PxL>C
the cost of human lives “probably” lost exceeds the cost of an
evacuation. Therefore, the evacuation might be called when
P>C/L
The evacuation will be called when the probability of
the deadly event will overcome a threshold defined a
priori by Civil Protection
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Application to MESIMEX
 BET_EF code applied to MESIMEX. The code is developed in the INGVDPC V4 project (leaded by W. Marzocchi & A. Zollo). The details are in
Marzocchi et al., 2007; Bull. Volc., in press.
 MESIMEX is an experiment (funded by European Community) simulating
a possible future reactivation of Vesuvio, aiming to check the procedures
for evacuation and managing the crisis. (The pre-eruptive scenario was
develop by researchers independently from this study. NO FEEDBACK,
BLIND TEST)
 Monitoring parameters and thresholds are taken from Marzocchi et al.,
JGR, 2004.A revision of parameters and thresholds is under consideration
in the project INGV-DPC V3_4 Vesuvius
You can download a report (in Italian) at the web site
http://www.bo.ingv.it/~warner
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Application to MESIMEX
17 Oct. 2006, 08:00; Probability per month
Conditional Probability of specific size: Monitoring-independent!
VEI=3: 64%
VEI=4: 25%
VEI=5+: 11%
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Application to MESIMEX
17 Oct. 2006, 09:00; Probability per month
 CO2 flux = 10 Kg m-2 d-1
 Other parameters inside the background
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Application to MESIMEX
18 Oct. 2006, 07:00; Probability per month
 Maximum magnitude in the last month = 4.2
 N. events in the last month = 38
 CO2 flux = 10 Kg m-2 d-1
 Seismic events localized out of crater
 Other parameters inside the background
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Application to MESIMEX
19 Oct. 2006, 09:00; Probability per month
 Maximum magnitude in the last month= 4.2
 N. events in the last month = 61
 LP events in the last month = 2
 T fumaroles = 100 0C
 CO2 flux = 20 Kg m-2 d-1
 Presence of SO2
 Localization of VT and LP
 Other parameters inside the background
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Application to MESIMEX
19 Oct. 2006, 18:00; Probability per month
 Maximum magnitude in the last month= 4.2
If we agreewith
a cost/benefit
ratio
of 0.1,
this is the moment
N. events
in the last
month
= 104
to evacuate
 LP events in the last month = 26
 T fumaroles = 110 0C
-2 d-1
 CO2 flux = 30 KgX m
0.35
= 0.22 > 0.1
 Presence of SO2
 5 10-5, d/dt = 5 10-5 d-1
 <3.6 Hz, d<dt = -0.4 Hz d-1
 Localization of VT and LP
 Other parameters inside the background
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Application to MESIMEX
20 Oct. 2006, 15:00; Probability per month
 Maximum magnitude in the last month= 4.2
 N. events in the last month = 183
 LP events in the last month = 61
 T fumaroles = 110 0C
 CO2 flux = 300 Kg m-2 d-1
 Presence of SO2
 1 10-4, d/dt = 5 10-5 d-1
 <3.5 Hz, d<dt = -0.5 Hz d-1
 Localization of VT and LP
 Other parameters inside the background
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Application to MESIMEX
21 Oct. 2006, 17:00; Probability per month
 Maximum magnitude in the last month= 4.2
 N. events in the last month = 258
 LP events in the last month = 131
 T fumaroles = 110 0C
 CO2 flux = 400 Kg m-2 d-1
 Presence of SO2
 3 10-4, d/dt = 2 10-4 d-1
 <2.5 Hz, d<dt = -1 Hz d-1 (tremor episodes)
 0.3 (variations in hypocenters location)
 Localization of VT and LP
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Points to take home
 BET is a transparent tool to calculate and to visualize probabilities
related to eruption forecasting/hazard assessment
 BET performed well during MESIMEX. This does not mean that will be
successful in forecasting the next eruption, but that it will represent
satisfactorily and quantitatively the average opinion of researchers.
 Cost/Benefit analysis is a very useful tool to interpret probabilities, i.e., it
helps to translate probabilities into practical actions. It needs a
collaborations between scientists (probability estimation) and decision
makers (cost/benefit analysis)
 The strategy adopted here has some clear advantages:
 it moves from subjective choices made during emergencies to
objective choices defined transparently BEFORE the occurrence of a
crises
 it is a “scientific tool”
 it creates a bridge between science and decision making
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Defence Secretary Donald Rumsfeld
illuminates the volcanological problem :
“There are knowns. There are things we know that we know.
There are known unknowns - that is to say, there are things
that we now know we don't know but there are also
unknown unknowns. There are things we do not know we
don't know. So when we do the best we can and we pull all
this information together, and we then say well that's
basically what we see as the situation, that is really only
the known knowns and the known unknowns. And each year
we discover a few more of those unknown unknowns.”
18 June 2003
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