Quantitative Risk AssessmentWalking through Simplified Example

What Would You Learn From This Exercise?Elements of Risk Quantification Risk = Frequency * Consequence

(1) Frequency AssessmentHazard IdentificationFrequency Assessmentbase-line frequencymagnitude-frequency 40 m80 m100 mGradient = 1:2(a) Hillside susceptible to landslides(b) Probable landslide volumes and frequencySectionPlan

Landslide Volume (m3)

(1) Frequency AssessmentHazard IdentificationFrequency Assessmentbase-line frequencymagnitude-frequency 80 m100 mABCDEach Hillside Unit Area = 100 m2

Landslide Volume (m3)

(1) Frequency AssessmentHazard IdentificationFrequency Assessmentbase-line frequencymagnitude-frequency

(1) Frequency AssessmentHazard IdentificationFrequency Assessmentbase-line frequencymagnitude-frequency

(2) Consequence AssessmentABCDConsequence AssessmentRunout distanceProximityVulnerability factorsFacility at riskPopulation at riskTable in C.2

(2) Consequence AssessmentAB

(2) Consequence AssessmentAB

(2) Consequence AssessmentABCDConsequence AssessmentRunout distanceProximityVulnerability factorsFacility at riskPopulation at risk

(2) Consequence Assessment

(2) Consequence Assessment

(2) Consequence AssessmentABCDConsequence AssessmentRunout distanceProximityVulnerability factorsFacility at riskPopulation at risk

(2) Consequence Assessment

(2) Consequence Assessment

(2) Consequence Assessment

(2) Consequence AssessmentLarge ScaleSmall Scale

(2) Consequence Assessment

(2) Consequence Assessment

(2) Consequence AssessmentABCDConsequence AssessmentFacility at riskPopulation at riskProximityRunout distanceVulnerability factors

(2) Consequence AssessmentABCDConsequence AssessmentFacility at riskPopulation at riskProximityRunout distanceVulnerability factors

(2) Consequence Assessment

(3) Risk EvaluationABCDRisk AnalysisPIRPLLF-N curveRisk dist.Risk TolerabilityCost-benefitRisk Mitigation

(3) Risk Evaluation

(3) Risk Evaluation

(3) Risk Evaluation

(3) Risk EvaluationRisk AnalysisPIRPLLF-N curveCost-benefitRisk ManagementDifferent Fatality Scenarios Risk AnalysisPIRPLLF-N curveRisk dist.Risk TolerabilityCost-benefitRisk Mitigation

(3) Risk EvaluationRisk AnalysisPIRPLLF-N curveCost-benefitRisk ManagementDifferent Fatality Scenarios Risk AnalysisPIRPLLF-N curveRisk dist.Risk TolerabilityCost-benefitRisk Mitigation

(3) Risk EvaluationRisk AnalysisPIRPLLF-N curveCost-benefitRisk ManagementDifferent Fatality Scenarios Risk AnalysisPIRPLLF-N curveRisk dist.Risk TolerabilityCost-benefitRisk Mitigation

(3) Risk EvaluationRisk AnalysisPIRPLLF-N curveRisk dist.Risk TolerabilityCost-benefitRisk Mitigation

(3) Risk Evaluation

(3) Risk EvaluationRisk AnalysisPIRPLLF-N curveRisk dist.Risk TolerabilityCost-benefitRisk MitigationABCD

(3) Risk EvaluationRisk AnalysisPIRPLLF-N curveRisk dist.Risk TolerabilityCost-benefitRisk Mitigation> 10-4 UNACCEPTABLEReference:Interim Risk Guideline (ERM, 1998)

(3) Risk EvaluationRisk AnalysisPIRPLLF-N curveRisk dist.Risk TolerabilityCost-benefitRisk MitigationReference: Interim Risk Guideline (ERM, 1998)Stabilization of Zones A to DSoil nailing at 1 m vertical and 1.5 m horizontal spacing:

No. of nails 7 x 20 = 140 Cost $5000 x 140= HK$ 0.7 M