Modelling Seismic Hazard in Earthquake Loss Models with Spatially Distributed Exposure

Abstract

The prediction of possible future losses from earthquakes, which in many cases affect structures that are spatially distributed over a wide area, is of importance to national authorities, local governments, and the insurance and reinsurance industries. Generally, it is necessary to estimate the effects of many, or even all, potential earthquake scenarios that could impact upon these urban areas. In such cases, the purpose of the loss calculations is to estimate the annual frequency of exceedance (or the return period) of different levels of loss due to earthquakes: so-called loss exceedance curves. An attractive option for generating loss exceedance curves is to perform independent probabilistic seismic hazard assessment calculations at several locations simultaneously and to combine the losses at each site for each annual frequency of exceedance. An alternative method involves the use of multiple earthquake scenarios to generate ground motions at all sites of interest, defined through Monte-Carlo simulations based on the seismicity model. The latter procedure is conceptually sounder but considerably more time-consuming. Both procedures are applied to a case study loss model and the loss exceedance curves and average annual losses are compared to ascertain the influence of using a more theoretically robust, though computationally intensive, procedure to represent the seismic hazard in loss modelling.

Ground motion scenarios consistent with probabilistic seismic hazard disaggregation analysis. Application to Mainland Portugal

“…So, disaggregated modal scenarios assessed from PSHA may be used to perform a seismic risk analysis for a region. In fact, risk analysis, with such simplified models will not involve the excessive effort, pointed out by Crowley and Bommer (2006), to compute loss exceedance curves for numerous sites.…”

Deaggregation of seismic loss of spatially distributed buildings

“…However, the HAZUS-Earthquake methodology lacks the consideration of spatially correlated seismic excitations. Recently, probabilistic seismic risk assessments of spatially distributed structures have been investigated by Crowley and Bommer (2006), Park et al (2007) and Goda and Hong (2008b). The study by Crowley and Bommer (2006) focuses on inter-event correlation of seismic demand, whereas those by Park et al (2007) and Goda and Hong (2008b) consider both inter-event and intra-event correlations of seismic demand.…”

“…Recently, probabilistic seismic risk assessments of spatially distributed structures have been investigated by Crowley and Bommer (2006), Park et al (2007) and Goda and Hong (2008b). The study by Crowley and Bommer (2006) focuses on inter-event correlation of seismic demand, whereas those by Park et al (2007) and Goda and Hong (2008b) consider both inter-event and intra-event correlations of seismic demand. Analysis results from these studies indicate that the impact due to correlated seismic excitations on seismic loss of a group of structures can be significant and such an effect needs to be taken into account adequately in dealing with catastrophic seismic risk.…”

Influence of spatial correlation of strong ground motion on uncertainty in earthquake loss estimation

“…Multiple earthquakes and loss probability curves were analysed by McVerry et al [14], Wesson and Perkins [10], Park et al [12], and Goda and Hong [37]. Bommer and Crowley [38] and Crowley and Bommer [39] discussed two approaches to calculating loss probability curves: one based on independent probabilistic SHA and the other involving Monte Carlo simulation based on the seismicity model.…”

“…Loss estimates were performed using the techniques based on different ground-motion characteristics (namely, Modified Mercalli intensities [14,35], peak ground acceleration [10,28] and spectral acceleration or spectral displacement [12,33,34,36,37,39]) and using various descriptions of loss (i.e. the mean damage ratio [10,28,33,34,36,39] and monetary loss [12,14,25,37]).…”