Advanced Workshop on Evaluating, Monitoring and Communicating Volcanic and Seismic Hazards in East Africa.

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1 Advanced Workshop on Evaluating, Monitoring and Communicating Volcanic and Seismic Hazards in East Africa August 2009 The assessment of volcanic hazards, vulnerability, risk and uncertainty Stephen Sparks University of Bristol U.K. Strada Costiera 11, Trieste, Italy - Tel ; Fax sci_info@ictp.it, www.

2 Assessment of volcanic hazards, vulnerability, risk and uncertainty Steve Sparks, University of Bristol, UK ICTP Workshop, Triest, 20 August, 2009

3 Hazard A volcanic hazard is any volcano-related phenomenon that threatens communities around a volcano Pyroclastic flow Lahar Volcanic hazards are described by the physical characteristics of the phenomenon, by the areas that they are expected to effect, by their magnitude and return period

4 Location

7 Destruction of Plymouth

8 Hazards maps are determined by mapping of past volcanic events and by modelling of the natural processes No flows Yellow is unexpected flow Predicted Flows Pyroclastic flow deposits Montserrat ( ) Pyroclastic flow models

9 A hazards map depicts areas likely to be affected by future volcanic activity and related phenomena (e.g. pyroclastic flows) Administrative zone maps are developed from hazards map but may take account of other factors (e.g. roads, infrastructure, etc) These maps used for planning and crisis management

10 Uncertainty Volcanic hazards maps are depictions of the LIKELIHOOD of future volcanic phenomena affecting places and people Volcanic phenomena are naturally variable, often complex and not fully understood There are many sources of uncertainty in forecasting the areas that volcanic activity will effect and the severity of the effects Uncertainties arise from: natural variability, inadequate data, biased data, incomplete data, lack of understanding of the processes, limitations to predictive models, ambiguity, unknown unknowns THE DESCRIPTION OF VOLCANIC HAZARDS IS THUS NECESSARILY PROBABILISTIC AND REQUIRES ASSESSMENT OF UNCERTAINTIES

11 Issues that arise from the probabilistic nature of volcanic hazards and the intrinsic uncertainties zonation maps require well-defined boundaries for pragmatism boundaries cannot divide areas that are completely safe from those that are unsafe levels of danger or safety need to be defined to decide on and justify boundaries through concepts of vulnerability (vulnerabilidad) and risk (reiesgo) more data, better observations, improved models may reduce uncertainties, BUT can increase uncertainties probabilities inferred by statistical techniques are hard to communicate

12 Hazards are only of concern when they pose risks to communities Risk = Vulnerability x Hazard Vulnerability and Risk defined in terms of humans and society

13 Vulnerability (Vulnerabilidad) m E m E m E 62E10'W m N m N N Montserrat (UK Overseas Territory) SILVER HILL 1000 Little Bay 2 km Carr's Bay l li n s R iv St John's m N G 1 er er l di So m N Gerald's Davy Hill Co Contour interval is 200 feet (metres = feet x ) Mongo Hill 100 St Peter's 0 ss le G Bo tt om ut ha Woodlands Pe W.H. BRAMBLE AIRPORT Farm Frith au St George's Hill 0 0 Richmond Hill F or u ha tg Gh au t 00 H ot R iver t t 's er Va ll ey Tar R iv Castle Peak 2 Roche's Mt Chances Peak SOUFRIE RE HILLS a ut St Patrick's au Gh 3 t Dry G h t au W h it e R r ive SOUTH SOUFRIE RE HILLS 0 G es ingo 20 0 Gh r's me Ay m N White's Yard Long Ground 4 Gages Mt 1 t PLYMOUTH Kinsale ut ha 10 t 10 Tu i Gh 's re Ty DTEZ Fox's Bay Farrell's Yard Dyer's 16E 45'N Spanish Point Bethel W D ye r's R ito G haut M os qu Cork Hill r er iv e R di s Tuitt's P a ra Windy Hill Streatham Garibaldi Hill e R iv Harris 1000 R Iles Bay F a rm B m ha el Old Road Bay m N P e a G ha ut Salem Old Towne Trant's CENTRE HILLS Nantes R i v e r 's G Olveston h ite 16E45'N 5 Jack Boy haut Hill ng lic a Katy Hill R 3b 3a 4 Lawye rs 2 Roche's Bluff m N Morris' 1000 main road m E 62E10'W St Pierre, Martinique (1902) 29,000 people died from a pyroclastic flow m E Fig. 4 Montserrat: population zones used for risk assessment modelling Typically volcanic vulnerability is defined in terms of people living in area under threat from volcanism

14 Risk Typically risk in volcanic crises is defined in terms of loss of life Individual risk: the chances of an individual being killed Societal risk: the chances of a society experiencing a certain number of deaths Normally expressed as annualised probabilities (chances of being killed in a year) These risks are not just determined by the hazard but are also influenced by human behaviour (e.g risk perceptions, denial, exaggeration of threat) and societal responses (e.g. land-use planning, evacuation, development strategies)

15 UK Individual Risk Scale HIGH >1 in 100 MODERATE 1 in 100 to 1 in 1000 LOW 1 in 1000 to 1 in VERY LOW 1 in to 1 in MINIMAL 1 in to 1 in a million Chief Medical Officer

16 Output as Risk Curves

17 Pooled estimates and opinions: What is the chance that a village 6 km NW of the volcano will be inundated by a pyroclastic flow?

18 Experts ability

20 Thank you

A disaster occurs at the point of contact between social activities and a natural phenomenon of unusual scale.

A disaster occurs at the point of contact between social activities and a natural phenomenon of unusual scale. Hazard Mapping and Vulnerability Assessment Mr. Toshiaki Udono Senior Project Manager, Kansai Division, PASCO Corporation, Japan Mr. Awadh Kishor Sah Project Manager, Project Implementation Department,