Training/workshop on Training/workshop on “Earthquake Vulnerability and Multi “ Earthquake Vulnerability and Multi- -Hazard Risk Assessment: Hazard Risk Assessment: Geospatial Tools for Rehabilitation and Reconstruction Effort Geospatial Tools for Rehabilitation and Reconstruction Effort” ” 13 - 31March 2006, Islamabad, Pakistan Introduct Intr oduction t on to Element ements a at Ri Risk Intr Introduct oduction t on to Element ements a at Ri Risk Samjwal Ratna Bajracharya International Centre for Integrated Mountain Development (ICIMOD) Material prepared from Lorena Montoya, Paul Hofste, and Cess van Western, ITC Associated Institute of the 1 (with material from Dr Arq. Lorena Montoya & Dr Cees van Westen)
Concepts Concepts Hazard = Probability of event with a certain magnitude Hazard = Probability of event with a certain magnitude Vulnerability = Degree of damage of element at risk Vulnerability = Degree of damage of element at risk Risk = The population, properties, economic activities, Risk = The population, properties, economic activities, including public services, etc. at risk in a given area. including public services, etc. at risk in a given area. 2
Natural hazard (H): Natural hazard (H): The probability of occurrence of a The probability of occurrence of a potentially damaging phenomenon within potentially damaging phenomenon within a specified period of time and within a a specified period of time and within a given area. given area. • Triggering mechanism Triggering mechanism • • Type of event Type of event • • Magnitude: Volume, domino effect, distance, duration, Magnitude: Volume, domino effect, distance, duration, • speed etc speed etc 3
Hazard types Hazard types � Extraterrestrial Extraterrestrial � � asteroid impact asteroid impact � Hazards are purely natural � Internal Geo Internal Geo- -dynamic processes dynamic processes � � Earthquake, tsunami, volcanic eruption Earthquake, tsunami, volcanic eruption � � External geodynamic processes External geodynamic processes � � Landslide, soil erosion, land degradation Landslide, soil erosion, land degradation � � Hydro Hydro- -meteorological meteorological � � Floods, Tropical storms, drought Floods, Tropical storms, drought � � Ecological / environmental Ecological / environmental � � Pollution, crop disease, Pollution, crop disease, � � Epidemics Epidemics � � SARS, HIV / AIDS, Avian Flu SARS, HIV / AIDS, Avian Flu � � Technological Technological � � (Industrial) accidents (Industrial) accidents � � Conflicts Conflicts Hazards are purely man-made � � War, land mines, terrorism War, land mines, terrorism � 4
Vulnerability (V) Vulnerability (V) The degree of loss to a given element or The degree of loss to a given element or set of elements at risk resulting from the set of elements at risk resulting from the occurrence of a natural phenomenon of a occurrence of a natural phenomenon of a given magnitude. It is expressed on a given magnitude. It is expressed on a scale from 0 (no damage) to 1 (total loss) scale from 0 (no damage) to 1 (total loss) 5
Fl Flood ood 1 10 y years R RP Flood hazard hazard Hazard type ? Flood Hazard type ? H = 0.1 H = 0.1 Hazard (H)=? Hazard (H)=? V = 1 V = 1 Vulnerability (V)= ? Vulnerability (V)= ? 6
Elements at risk Elements at risk The population, properties, economic activities, The population, properties, economic activities, including public services, etc. at risk in a given including public services, etc. at risk in a given area. area. RISK = HAZARD * VULNERABILITY * AMOUNT RISK = HAZARD * VULNERABILITY * AMOUNT Amount = Quantification of the elements at risk e.g. Amount = Quantification of the elements at risk e.g. • Replacement costs of buildings, infrastructure etc. • Replacement costs of buildings, infrastructure etc. • Loss of function or economic activities Loss of function or economic activities • • Number of people Number of people • 7
Hazard, vulnerability and risk? Hazard, vulnerability and risk? RISK = HAZARD * VULNERABILITY CAPACITY Capacity = expresses the positive Capacity = expresses the positive managerial and operational resources and managerial and operational resources and procedures for reducing risk factors procedures for reducing risk factors 8
Risk? Risk? � Example: Example: � US $ 50,00 $ 50,000 10 y 10 year ears R RP V = 1 V = Hazard = probability within a given period • = 0.1 / year Vulnerability = degree of damage = 1 • Risk = hazard * vulnerability * amount • = 0.1 * 1 *50,000 = 5,000 US $ 9
Hazard, vulnerability and risk? Hazard, vulnerability and risk? � Example: Example: � US $ 200.0 $ 200.000 US $ 50.00 $ 50.000 US $ 100.0 $ 100.000 V = V = 0.5 V = V = 0.1 10 year 10 y ears R RP V = V = 1 � Risk = hazard * vulnerability * amount = 0.1 * ( (0.5*200.000)+ (0.1*100.000)+ (1 * 50.000)) = 0.1 * 160.000 = 16.000 $ 10
Hazard, vulnerability and risk? Hazard, vulnerability and risk? � Example: Example: � US $ 50.00 $ 50.000 50 y 50 year ears R RP V = V = 1 V = V = 0.1 10 year 10 y ears R RP 2 y 2 year ears R RP V = = 0.01 0.01 � Risk = 0.5 * 0.01 * 50.000 + 1 0.1 * 0.1 * 50.000 + Risk c Ri sk curve rve 0.02 * 1 * 50.000 = 0.5 0.5 = 250 + 500 + 1000 0.1 0.1 = 1750 US $ 0.02 0.02 0 0 1000 1000 10000 10000 11
Elements at risk Vulnerability N ∑ = Risk P E V ( i ) ( i ) ( i ) i For all Consequence credible Probability hazards of failure 12
In reality In reality � Example: Example: � Price is Pr ice is ? ??? Depth = th = ???? ???? RP RP = = ?? ?? V = = ???? ???? � Risk = hazard * vulnerability * amount = ? * ? * ? = unknown What is needed: hazard assessment , elements at risk mapping, vulnerability assessment, cost estimation. 13
Landslide risk assessment Landslide risk assessment US $ 50.00 $ 50.000 US $ 100.0 $ 100.000 US $ 200.0 $ 200.000 V = V = 0.1 V = V = 0.5 10 y 10 year ears R RP V = 1 V = P= P=0.02 V 0.02 V = = 1 1 US $ 50.00 $ 50.000 P= P=0.1 V 0.1 V = = 0.1 0.1 P=0.5 V P= 0.5 V = = 0.01 0.01 14
Risk = Hazard * Vulnerability * Amount Risk = Hazard * Vulnerability * Amount � Very complicated topic Very complicated topic � US $ 50.00 $ 50.000 50 y 50 year ears R RP V = 1 V = V = V = 0.1 10 year 10 y ears R RP 2 year 2 y ears R RP V = = 0.01 0.01 1 In practice this is very complicated: • Quantifying probability Risk c Ri sk curve rve • Mapping all elements at risk 0.5 0.5 • Quantifying vulnerability • Multi-hazard risk assessment 0.1 0.1 0.02 0.02 0 0 1000 1000 10000 10000 15
Concepts Concepts � Risk Risk = the = the expected expected number of lives lost, people number of lives lost, people � injured, or economic losses due to a potentially injured, or economic losses due to a potentially damaging phenomenon within a period of time. damaging phenomenon within a period of time. � Risk information can be used to Risk information can be used to reduce reduce the hazard the hazard � probability (zoning) or the vulnerability (building probability (zoning) or the vulnerability (building codes), and thereby reduce the risk. codes), and thereby reduce the risk. The information has to be comprehensive comprehensive and and up up- -to to- - The information has to be date . . date � In addition, risk information is vital for In addition, risk information is vital for disaster disaster � response planning. . response planning 16
Why address risk? Why address risk? Risk assessment & management If done properly, it will lead to the reduction , and possibly elimination of risk 17
Recommend
More recommend
