User guide: Field sampling strategies for estimating building inventories

The Global Earthquake Model (GEM) aims to provide a set of tools and models for hazard and risk analysis. The fundamental aim of the GEM Inventory Data Capture Tools (IDCT) risk global component is to provide a set of software and accompanying user protocols to enable users to collect and modify building exposure information, which can be input into the Global Exposure Database and the Global Earthquake Consequences Database.

This report offers procedures to estimate the area distribution of building types in a community through a combination of remote sensing, local expertise, and field observations. The resulting inventory can be used for probabilistic seismic risk analysis. By providing here four sampling strategies, based on a classification of building types for a specific community geographical area (called zone), and throught a two-step procedure of mapping, it is estimated that one team of two people can survey enough buildings to represent the distribution of one zone in approximately one day.

Part of the strategy is a separate procedure set for special buildings, such as buildings that serve some important function or are known to be particularly seismically vulnerable or particularly seismically resilient.  An appendix provides the mathematical basis of these procedures, including stratified sampling, Bayesian updating, and a discussion of the trade-off between sample size and sensitivity to rare building types.