During the semester

1. During the semester • Introductions • Basics of earthquakes • History and Recording • Damaging Earthquakes and understanding seismic exposure • Undertaking loss assessment • Seismic analysis; and design and detailing (RCC and Masonry)

2. Understanding Seismic Exposure Objectives • To enable most informed decision • Clarity • Decision Making • Disaster Planning : Mostly qualitative • Loss estimation: Mostly quantitative • Designing/Retrofitting : Mostly quantitative

3. Understanding Earthquake loss Various definitions such as: • [Risk] = [Hazard] . [ Vulnerability .or. Exposure ] • [ Risk ] = [Likelihood] . [ Value at stake]

4. Understanding Earthquake loss Think about risk in a logical way • 1 x 10 = 10 • 10 x 1 = 10 • 1 x 1 = 1 • 10 x 10 = 100 • 1 is lowestrisk • 100 is highestrisk • Is 10 medium risk?

5. Understanding Earthquake loss Risk A quantifiable term for • Life • Injury • Property damage • Immediate disaster response • Mitigation: Insurance, retrofitting A qualitative term for • Trainings • Long term disaster recovery • Business interruption

6. Understanding Earthquake loss Approaches for Seismic Hazard & Risk Probabilistic • Return Period (T) • Inverse of the probability of an event; p = 1/T Deterministic Prepare for worst scenario at a particular location

7. Probabilistic approach • Return period = T [years] • Probability of Occurrence = p = 1/T [annual] • Probability of Non Occurrence = q = 1 - p [annual]

8. Probabilistic approach Probability of occurrence of event ‘r’ times in ‘n’ years is found using a binomial distribution P r,n = nCr . pr . qn-r P r,n = { ( |n ) / ( |n-r) ( |r ) } . pr . qn-r Probability of event occurring once in a year, r = 1 P 1,n = { ( |n ) / ( |n-1) ( |1 ) } . p1 . qn-1 P 1,n = ( |n / |n-1) . p1 . qn-1 P 1,n = n . pqn-1 • Probability of event not occurring at all , r = 0

9. Probabilistic approach • Probability of event not occurring at all , r = 0, in ‘n’ years • P 0,n = { ( |n ) / ( |n-0) ( |0 ) } . p0 . qn-0 = ( |n / |n). qn-0 • or,P 0,n = qn • or,P 0,n = ( 1 - p )n • Also, probability of event occurring ONCE in ‘n’ years • P 1,n = 1- qn = 1- (1-p)n  Represented also as R (Risk)

10. Probabilistic approach • Q. An earthquake of certain magnitude has a return period of 25 years. • What is the probability of exceedance? • What is the probability that the same earthquake will happen in 10 years? • What is the probability that the same earthquake will happen in 100 years? • What is the probability that the same earthquake will happen in 500 years?

11. Probabilistic approach • An Exercise • A. • i. T = 25 years • p=1/T = 1/25 = 0.04 • --------- • ii. p0,n = qn = (1-p)n • p0,10 = (1-0.04)10 = 0.664 • Thus, Probability of occurrence = 1-0.66 = 0.34 • iii. p0,100 = (1-0.04)100 = 0.017 •  Thus, Probability of occurrence = 1-0.017 = 0.98 • iv. p0,500 = = (1-0.04)500 = 1.37 x10-9 • Thus, Probability of occurrence = 1-1.37 x10-9 = 0.99999999863, which nearly equals 1

12. Probabilistic approach • iv. p0,500 = = (1-0.04)500 = 1.37 x10-9 • Thus, Probability of occurrence = 1-1.37 x10-9 = 0.99999999863, which nearly equals 1

13. Understanding Earthquake loss Hazard Earthquake is a hazard itself and represents ground shaking and motion. Defined parameters such as: • Peak Ground Acceleration (PGA) • Liquefaction (local soil action)

14. Understanding Earthquake loss Vulnerability/Exposure • Who is vulnerable/exposed? • Building • Population • Type of Building: Lateral load resisting system • Numerative details: Area, Building Value, Population • Damage /fragility/vulnerability curves • Building Use and Occupancy: Hospital/Nuclear facility/ School / Residential • Building Construction history? • Quality of design • Quality of workmanship

15. Understanding Earthquake loss Vulnerability/Exposure Damage /fragility/vulnerability curves 0 to 100% Damage

16. Understanding Earthquake loss Mitigation • Retrofitting efforts and cost • Maximum probable loss • Maximum damage value • Cost benefit analysis

17. in Ahmedabad - Sample case • Seismic loss assessment of a building • Building types classifiable on material and technological know how • Majority of building types • RCC Frame • Masonry • Reinforced Masonry • Uncategorized

18. Building types in Ahmedabad Note: Numbers are approximate for illustration purposes

19. Loss Assessment of a Building Summarize / Evaluate • Location. PGA hazard value = _____ g • Vulnerability / Exposure = _____ units • Loss = _____ % • Mitigation = _____ units

20. Discuss • ISR visit lessons (Ground motion and sensors) • Submit assignment No. 2 later – 7th Feb • Book reading? How to write a book review