قارن الطرق

	Exposure Modeling (Disaster Risk)	Average Annual Loss Estimation
المجال	Disaster Studies	Disaster Studies
العائلة	Process / pipeline	Process / pipeline
سنة النشأة	2017	2005
صاحب الطريقة	Catalina Yepes-Estrada & Vitor Silva (GEM); GEM Foundation global exposure program	Patricia Grossi & Howard Kunreuther; Vitor Silva et al. (GEM)
النوع	Spatial-inventory construction pipeline for elements at risk	Expected-value risk metric computed from a loss exceedance distribution
المصدر التأسيسي	Yepes-Estrada, C., Silva, V., Valcárcel, J., Acevedo, A. B., Tarque, N., Hube, M. A., Coronel, G., & Santa María, H. (2017). Modeling the Residential Building Inventory in South America for Seismic Risk Assessment. Earthquake Spectra, 33(1), 299-322.	Grossi, P., & Kunreuther, H. (Eds.) (2005). Catastrophe Modeling: A New Approach to Managing Risk. Springer. ISBN: 9780387241050
الأسماء البديلة	Exposure Database Development, Asset Inventory Modeling, Building Exposure Model, Elements at Risk Mapping	Annual Average Loss (AAL), Annualized Expected Loss, Pure Premium Estimation, Expected Annual Damage
ذات صلة	4	4
الملخص	Exposure modeling builds the geolocated inventory of assets, people, and values that are at risk from a hazard, the elements-at-risk layer that, together with hazard and vulnerability, determines disaster loss. It answers what is where and worth how much: how many buildings of each construction type sit in each location, their replacement value, and the population that occupies them at different times of day. Catalina Yepes-Estrada, Vitor Silva, and colleagues' 2017 South America residential exposure model and Vitor Silva and colleagues' 2020 global seismic risk model exemplify the modern approach of synthesizing census statistics, building characteristics, and expert mapping into open, georeferenced databases. Because loss equals hazard acting on exposure through vulnerability, exposure accuracy often dominates the realism of a risk estimate. Exposure models feed catastrophe models, HAZUS-style loss estimation, and probabilistic risk metrics like average annual loss. Constructing them well, with consistent taxonomy, credible values, and validated counts, is foundational to all downstream disaster risk analysis.	Average annual loss (AAL) estimation computes the expected loss per year from a hazard, the long-run mean of annual losses obtained by weighting every possible event's loss by its annual frequency. It is the single most important summary statistic produced by probabilistic risk and catastrophe models, equal both to the frequency-weighted sum of event losses and to the area under the loss exceedance curve. Patricia Grossi and Howard Kunreuther's 2005 volume sets out how AAL and the exceedance curve are derived and used in risk management, and Vitor Silva and colleagues' 2020 global seismic risk model reports AAL (and AAL ratios) as its headline risk metric across the world. Because it is an expected value, AAL is additive across assets, perils, and regions, which makes it ideal for ranking risk, setting the technical (pure) insurance premium, and screening mitigation. Unlike return-period losses it says nothing about the tail, so it is the complement to probable maximum loss rather than a substitute. Estimating it correctly means handling both frequencies and the full range of event losses, including rare severe ones.