Limitations of risk-based disaster reduction Tim Davies University of Canterbury, New Zealand COMMUNITY DISASTER REDUCTION CANNOT BE ACHIEVED USING RISK Something to think about:

RISK: “The combination of the probability of an event and its negative consequences.” DISASTER RISK REDUCTION: “The concept and practice of reducing disaster risks through systematic efforts to analyse and manage the causal factors of disasters…” DISASTER RISK: “The potential disaster losses, in lives, health status, livelihoods, assets and services, which could occur to a particular community or a society over some specified future time period.” Some definitions: (UNISDR) RELEVANT FUTURE TIME PERIOD: a (few) hundred years at most DISASTER: “A serious disruption of the functioning of a community…” Take-home message: this implication is false Implication: Probabilistic (risk) information can be useful in reducing the disasters that will affect communities in a relevant future time period

How many disaster events will a particular community experience in a (few) hundred years? Disasters are by definition serious events, so occur infrequently; if they occurred more frequently, people would expect them and they would no longer be serious. The number of disaster events a community will experience in a relevant timeframe is small. In small samples, large discrepancies can occur between probabilistic predictions and actual occurrences, even with prefect statistics: Toss a coin once, will you get half a head?

Predictions of the occurrence of future disasters are intrinsically unreliable for particular communities, so cannot be used to devise reliable disaster reduction strategies for them. Such predictions are reliable for predicting the occurrence of large numbers of disasters, e.g. for national or global agencies, or for insurance and re-insurance Any community is MOST interested in the NEXT disaster that will affect it, and this cannot be predicted probabilistically. National and global disaster reduction strategies cannot succeed if community disasters are not reduced; so disaster reduction at all scales needs to look beyond risk-based strategies.

Thank you for listening Local disaster reduction CAN be achieved by reducing vulnerability to disaster effects (e.g. structural damage, lifeline destruction, loss of commerce) using community-based resilience research and planning.