Earthquake Vulnerability and Exposure Analysis Session 2 Mr. James Daniell Risk Analysis Earthquake Risk Analysis 1

Risk Analysis Earthquake Risk Analysis 2 Learning Objectives  Learn about the inventory elements at risk that are exposed to the hazard  Learn how to collect data for exposure  Know the difference between empirical and analytical methods for vulnerability analysis  Know the types of vulnerability scales for buildings and infrastructure  Know the importance of socio-economic vulnerability assessment and its role in the decision making processes  Apply vulnerability assessment to a real situation

Risk Analysis Earthquake Risk Analysis 3 What elements are at risk?  All forms of man-made structures are at risk.  It is important to know the key elements to characterise a region.  Building Infrastructure - Any man-made construction, either urban or rural. ResidentialCommercialIndustrial ‘Elements at risk’, infrastructure, residential, commercial, industrial

Risk Analysis Earthquake Risk Analysis 4 What elements are at risk?  Transportation Road, rail, air and other transport-related networks  Large Loss Facilities Sports stadiums, marketplaces, churches/temples/mosques, schools and other high population density infrastructure  Critical/High-Risk Loss Facilities Hospital and health care facilities, public buildings, telecommunications, airports, energy systems, bridges and other facilities critical to the recovery of a region post-earthquake  Other Lifelines – Utilities, Pipelines Oil, gas and water supply pipelines/distribution systems, wastewater and electricity systems Transportation, large loss facilities, critical loss, high-risk, lifelines

Risk Analysis Earthquake Risk Analysis 5 What do we collect for exposure data?  Is the data there? It depends on scale and country type  Local – Council data, local government agencies, aerial photos, individual architectural, structural drawings  Regional – State-based agencies, statistical offices, census data, investment and business listings, employment figures, existing GIS data.  National – National statistical agencies, census data, global databases, remote sensing Exposure scale, Local, Regional, National

Risk Analysis Earthquake Risk Analysis 6 What type of data is needed for exposure  Elements at risk characterization Number, type, location, size, height, age, construction cost, land value, irregularities, material and mechanical properties  Population details Day/night occupancy of people  Microzonation data Geological data, shear wave velocities, coastal information, elevation, nearby slopes and fault information  Government/Regional data Building code knowledge, previous earthquake damage reports, social and economic datasets Population data, Microzonation, Government data, building code.

Risk Analysis Earthquake Risk Analysis Construction Material + Design 7 So what is physical earthquake vulnerability?  “Susceptibility of the ‘elements at risk’ to the earthquake hazard”  If a structure is likely to be damaged in an earthquake, it has a HIGH vulnerability  What are the main factors contributing to vulnerability? Age & Condition Irregularities Location

Risk Analysis Earthquake Risk Analysis 8 Ground Motion and its relationship to damage  Buildings vibrate at a certain fundamental building period depending on their building structure, height, stiffness and mass.  Seismic waves with periods close to that of the building will cause resonance (strong vibrating of the building)  A lot of earthquake energy is generally contained in the short- period waves and thus smaller buildings must be designed for larger forces. Resonance, fundamental period, flexible vs. stiff buildings

Risk Analysis Earthquake Risk Analysis 9 Vulnerability of the built environment  Single building vs. Group of buildings structural analysis  For a group of buildings, there are three different calculation methods for earthquake vulnerability; empirical, analytical or hybrid. Empirical constructed from historic earthquake damage loss ratios and assessment. Analytical constructed via mathematical and mechanical formulae to characterize the given damage per ground motion Hybrid A combination of various empirical data with an analytical method Empirical, Analytical, Hybrid vulnerability methods.

Risk Analysis Earthquake Risk Analysis 10 Empirical vs. Analytical Vulnerability Empirical, Analytical, Qualitative, Hybrid vulnerability methods. Increasing complexity Decreasing complexity Increasing uncertainty Decreasing uncertainty (better!) Increasing Computation Time Decreasing Computation Time More Parameters needed Less Parameters needed EmpiricalAnalyticalQualitative

Risk Analysis Earthquake Risk Analysis 11 Empirical Vulnerability Methods  Damage Probability Matrices Historical ratios of probable damage for each building type for a given ground motion.  Vulnerability Indices and Curves A continuous function of intensity vs. damage – “fragility curves”.

Risk Analysis Earthquake Risk Analysis 12 Empirical Vulnerability Methods Bal et al., 2006, 2008 Screening Methods – These methods involve assigning a vulnerability rating, given different structural characteristics on a infrastructure-by-infrastructure basis usually via site visit. This also works well for vulnerability lifelines.

Risk Analysis Earthquake Risk Analysis 13 Analytical and Hybrid Vulnerability Methods  Analytical vulnerability indices and collapse-based methods rarely used.  Capacity Spectrum methods – finding the intersection point between hazard and vulnerability. Analytical curves, Collapse-Based, Capacity Spectrum Method F FOR Group of buildings of same building type and hazard is defined by response of a single similar building Capacity of the building: what can the building withstand? Demand on the building: the earthquake hazard applied to the building

Risk Analysis Earthquake Risk Analysis 14 Damage Classes Damage Class Adapted from Rossetto and Elnashai, 2003 Expected building damage ratios are calculated using vulnerability methods, and are classified in a number of limit/damage states – none, slight, partial, moderate, severe and collapse or otherwise.

Risk Analysis Earthquake Risk Analysis 15 Capacity Spectrum Method  By finding the performance point, the spectral response is used by pre- defined probabilities of lifelines or infrastructure failure.  Important to know, as the most common in the world. Performance Point, fragility function Where the performance point is, changes the damage states of the buildings.

Risk Analysis Earthquake Risk Analysis 16 What is socio-economic vulnerability to earthquakes?  Socio-economic vulnerability is concerned with the study of the impact of earthquakes on social and economic systems – “community vulnerability”  The flow-on effects of earthquakes in terms of recovery and damage to life systems sometimes outweigh the physical damage effects of earthquakes.  Socio-economic vulnerability of a community is often modeled by Design of models which explain vulnerability and the root causes which create it, and The development of indicators and indexes which attempt to map vulnerability over time and space Socio-Economic vulnerability, flow-on effect, recovery, fragility, resilience

Risk Analysis Earthquake Risk Analysis 17 What is socio-economic vulnerability to earthquakes?  Socio-economic vulnerability is concerned with the study of the impact of earthquakes on social and economic systems – “community vulnerability”  The flow-on effects of earthquakes in terms of recovery and damage to life systems sometimes outweigh the physical damage effects of earthquakes.  Socio-economic vulnerability of a community is often modeled by Design of models which explain vulnerability and the root causes which create it, and The development of indicators and indexes which attempt to map vulnerability over time and space Socio-Economic vulnerability, flow-on effect, recovery, fragility, resilience