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Warning and Evacuation

  1. Warning and Evacuation in Disaster Situations David Alexander University College London
  3. KANSAS 5 dead, 150 injuredOKLAHOMA 38 dead, 669 injured TEXAS 1 dead, 12 injured Monday 3 May 1999 76 tornadoes in 7 hours damage exceeded $500 million 4319 buildings destroyed WARNING TIME: 20-120 minutes ONLY 44 DEATHS Largest tornado max. F5 (420-510 km/hr) path 130 km x 1.5 km
  4. What does this picture tell us about warning and preparedness?
  5. Definition:- A warning is a recommendation or order for action to take place based on a prediction or forecast.
  6. Predictions and forecasts should be made by scientists (or other appropriate and qualified experts) Warnings should be issued by civil authorities (such as as an emergency management agency) on the basis of valid predictions.
  7. Scientists Hazard Evaluation Administrators Risk communication Decision to warn General Public Warning Protective action The warning process Organisational SocialTechnical Precise Diffuse
  8. Factors that influence the effectiveness of a warning • how predictable the hazard is • how long the precursors (if any) last • how quickly the disaster strikes (speed of onset) • how far the impact can be controlled • frequency, duration and size of impact.
  9. A warning system consists of a combination of:- • physical and social components • technology and organisation • planning and communication. • monitoring and evaluation
  10. Stages in the warning process • decision-makers recognize existence of hazard and decide to create a warning system • they decide who to warn, about what, and how to warn them • a system is designed to monitor changes in the hazard and issue warnings • the system is installed and tested.
  11. • what is likely to happen - the nature of the impact • when it is likely to happen - the time window of the prediction • where it is likely to happen - the geographical area affected. What a warning message should say:-
  12. What a warning message should say:- • what actions are required • who to contact for further information. • what the consequences of the impact are expected to be • whether the response is obligatory or merely recommended
  13. Stages in the warning process • the public must be educated to respond appropriately to a warning • the system must be tuned to make it work better • changes in the hazard are detected and monitored • incoming information is collated and evaluated.
  14. The phases of warning:- • warning message sent • content evaluated • risk perceived • choice of behaviour • action taken (choice realised). • message received
  15. Transmission of warning messages:- • a hazard watch - "conditions have occurred that normally precede a disaster" • a hazard warning - "impact is certain, or at least very likely".
  16. Post-warning actions • issue of all-clear, stand-down and end-of-emergency messages • debriefing and hindsight review • revising and testing the warning system.
  17. Factors that influence the effectiveness of a warning:- • what the probable consequences of the impact are • how much assistance is available • quality of personnel and command structure • legal responsibilities.
  18. Warning messages that succeed are:- • from official (and credible) sources • clear, consistent, precise • repeated and confirmed • the content of messages • how messages are interpreted. But social factors influence... • the channels of communication
  19. People interpret warning messages differently according to... • circumstances • personality factors • revised and repeated warning messages will almost certainly be needed. • social contexts Public reaction to warnings needs to be monitored and the results fed back to the issuers of warnings
  20. The initial response to warnings tends to be disbelief, followed by confirmation behaviour Public awareness and participation are crucial to the success of warning systems.
  21. Warning verification processes • normalcy bias: lack of confirming evidence (usually visual) • latent confirmation: does the information square with beliefs and personal knowledge? • socialisation of response: seeking confirmation from family, friends and colleagues • contact with officialdom.
  22. • unconflicted inertia: the tendency to undervalue warnings • cognitive dissonance: unease when two conflicting beliefs are held simultaneously • some deviant behaviour is possible. • panic is an unlikely response to warnings
  23. People who react best to warnings • are under 40 but over 25 • are female • are not members of an ethnic minority • have not lived long in the area but are well integrated with the community and its institutions.
  24. • have middle-to-high social status • are parents with children living at home • live near relatives and utilise kinship networks • are well able to understand the risk. People who react best to warnings
  25. How much time does it take to warn a community of modest dimensions (a small town, for instance)? • 3-4 hours for 90% of inhabitants • using various means of communication: - official emergency personnel - informal contacts - the mass media • longer warnings lead to more confirmation behaviour • confirmation is most important when impacts are common.
  26. Examples of imprecise predictions that led to inefficient warnings • an 86% chance of a magnitude 7 earthquake in Southern California in 25 years • a 5% chance that a magnitude 5.1 earthquake would occur in the San Francisco Bay region during specified 5-day periods • a 20% chance of a magnitude 5.1 or greater in a restricted area of S. California over a 30-day period.
  27. Nevado del Ruiz, Colombia, Nov. 1985: the worst failure of warning processes in modern times.
  28. Nevado del Ruiz, 13 November 1985 • a nocturnal phreatic eruption with attenuated precursors • 23,000 dead in lahars (mudflows), most in the town of Armero • a hazard map had been made • the volcano was heavily instrumented • there was a failure of communication between scientists, civil authorities and the general public.
  29. Parkfield, California, 1992-3: a 90% chance of a mag. 6 earthquake 300 scientific instruments deployed, 80 of them recording continuously
  30. The earthquake didn't happen!
  32. Evacuation is the most widespread and effective short-term measure to protect the public against sudden-impact disasters BUT: it is not always appropriate, feasible or advisable.
  33. Types of evacuation Sort-term Long-term Pre-impact Emergency protection Preventative Post-impact Rescue For reconstruction
  34. The 'evaluation-dissemination subsystem' • identify and measure risk • collect and interpret data • decide to evacuate • determine content of message to public • apportion these tasks to appropriate agencies. • transmit message • direct evacuation and monitor result
  35. The phases of evacuation • decision time • notification time • evaluation time • preparation time • verification time. • journey time
  36. Some precepts of evacuation • evacuation should only be attempted if there is enough time to accomplish it • evacuation should move people into progressively safer areas, not through areas of danger • bottlenecks must be managed • destinations need to be planned.
  37. The evacuee's choice • be unaware and do nothing • understand the risk but do nothing • do something to protect oneself, but not evacuate • prepare to evacuate but not go • evacuate.
  38. Immediate adaptive actions ADAPTIVE Eventual adaptive actions Efforts to confirm information Failure to act on received information Total denial of threat MALADAPTIVE A CONTINUUM OF PUBLIC REACTIONS TO HAZARD IMPACT WARNINGS Supply interpretable information ADAPTIVE Supply "raw" information Supply theoretical information Fail to deliver information Have no applied contacts MALADAPTIVE? A CONTINUUM OF SCIENTISTS' REACTIONS TO THE NEED FOR USABLE INFORMATION
  39. Sociological processes in family evacuation Evacuation by.... • default • invitation • compromise • decision.
  40. Things that facilitate evacuation • a personal action plan • is what the mass media say consistent? • can one calm fears of looting? • are there public information centres? • do potential evacuees have faith in the authorities and institutions that issue the evacuation order? .
  41. Factors that influence the choice of destination • will relatives offer shelter? • how long is the warning time? • how long is the evacuee expected to be away from home? • how well-prepared is the evacuee? • from what social class is the evacuee? • what is the risk?
  42. Efficiency of evacuations as reported in the research literature (Sorenson & Mileti 1988 and other sources) • minimum 32% in low-risk areas • maximum 98% in high-risk areas • almost 90% left within 1 hour • nearly 60% left within 10 minutes • 60-88% went to friends and relatives. • 6-36% went to public shelters [X]