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Disaster Risk Reduction for Extreme Geohazards
Hans-Peter Plag, Climate Change and Sea Level Rise Initiative, Old Dominion University, Norfolk, VA, USA
Shelley Jules-Plag, Tiwah, Inc., Reno, NV, USA
Seth Stein, Northwestern University, Evanston, IL, USA
Sean Brocklebank, University of Edinburgh, U.K.
Stuart Marsh, University of Nottingham, U.K.
Paola Campus, European Science Foundation, Strasbourg, France
Supported by:
Geohazards Community of Practice of the Group on Earth Observations (GEO)
European Science Foundation (ESF)
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Why Extreme (Geo)Hazards?
The growing, interconnected and increasingly exposed global population faces a mounting risk of a global catastrophe caused by extreme natural hazards.
The problem:
- extreme hazards occurred in the past, but little exposure often limited the disaster
- increased exposure leads to more frequent disasters
- complexity of modern societies leads to more indirect effects
- sustainability crisis reduces resilience

Why Extreme Geohazards?
White Paper on Extreme Geohazards:
• What is the problem?
• What do we know and not know?
• What are we trying to accomplish?
• What strategies are available?
• What are the costs and benefits of each?
• What is the optimal strategy given various assumptions and the uncertainty involved?
• What are the societal and governance processes that could facilitate disaster risk reduction?

Terminology
Extreme Events:
• Extinction Level Events: more than a quarter of all life on Earth is killed and major species extinction takes place.
• Global Catastrophes: more than a quarter of the world human population dies and that place civilization in serious risk.
• Global Disasters: global-scale events in which a few percent of the population die.
• Major Disasters: disasters exceeding $100 Billion in damage and/or causing more than
10,000 fatalities.
Modified from Hempsell (2004)
Extreme events - X-Event: Rare, surprising, high impact events
X-ness X: E: total annual death/gross domestic product delta E: change due to event
U: Unfolding time
I: Impact time
Modified from Casti (2012)

Measuring Impacts
Tsunami Earthquake Earthquake Cyclone Earthquake

Extreme (Geo)Hazards
The problems:
- knowledge of rare events is limited
know better the “why” and “how” but not the “when”
- propability is difficult to assess
- risk assessment is challenged
Poisson distribution; Chance that one or more
“1 in N years” events occur in a century:
th

Earthquakes

Volcanic Eruptions

Volcanic Eruptions
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1) Krakatau was similar to Santorini eruption, 1600 BC, although 4 times smaller
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Several eruptions that happened during the last 2,000 years would be devastating under todays conditions

Extreme Hazards

Cost-Benefit Analysis
Toba, 75,000 years ago, VEI 8, 2,800 km3; killed 60% of human population
Impacts:
- ash layer, several million square kilometers
- destroying one or two seasons of crops for two billion people
- reducing global temperature by 5-15 C
- substantial physical damage to infrastructure
Death comparable to other global disasters:
- 1918 Spanish flu: 3% - 5% of global population
We assume:
- 10% of global population is killed if volcano eruption comes as a surprise

Cost-Benefit Analysis
- Value of statistical life (VSL): $9.1 million (U.S. Department of Transportation)
- U.S. citizen should be willing to spend $910 to eliminate a 1 in 10,000 risk of fatality
- Global VSL: $2.22 million
Toba-type eruption: 1 in 100,000 years; fatalities 10%:
Probability of a random person dying in any particular year: 1 in 1,000,000.
Average person should be willing to pay $2.22 per year to eliminate the risk.
Global population over 7 billion: $15 billion per year.
Eliminating half of the risk is worth $7.5 billion per year.
2014 USGS Budget: $24.7 million for volcano monitoring
Same level globally: $370 million

Conclusion
The largest volcano eruptions that occurred during the most recent millennia would today threaten an already stressed food supply and challenge the crucial global transportation network and, without rapid preparation, could easily lead to a global catastrophe.
We have roughly a 20% chance that a major eruption takes place in the 21st century with severe implications for food security, public health, transportation, and global economy.
An elaborate, comprehensive volcano observing system needs to be a core element of disaster risk reduction - from a CBA point of view, we should be willing to to spend a lot (> $500 M/year).
GHCP is reviewing requirements for this observing system
We need to study how to improve preparedness and what to do with early warnings; we propose a dedicated international institute for this
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