Optional output of earthquake rupture forecast for user-specified geographic region (Event Sets)
BACKGROUND. For a given site (i.e., lat/lon pair) and intensity measure type (IMT), nshmp-haz gives the final hazard curve for the IMT. This hazard curve can also be determined by first outputting the underlying Earthquake Rupture Forecast (ERF) and then applying the corresponding ground motion models (GMMs). If a different nearby site was of interest, then a slightly different ERF would be used, depending on the distance cutoff for earthquake sources and the distance between the two input sites.
TARGET OUTCOME. Modifying nshmp-haz to be able to output the underlying ERF for a given set of sites that define a geographic region. OpenSHA's "IM_EventSetCalc_v3_0_ASCII" calculator already does this by outputting a matrix where each row corresponds to a unique earthquake rupture in the ERF; for each ERF, OpenSHA provides the annual rate of rupture occurrence and the distances between the rupture and all the input sites of interest.
USE CASE. The ability to output underlying ERF for a set of sites will facilitate regional seismic risk assessment using Monte Carlo simulation and related techniques. For example, the ERF can be used to probabilistically generate GM maps that account for spatial correlation of GM; although these simulated GM maps will essentially reproduce the marginal hazard curves from nshmp-haz for each site, the inclusion of spatial correlation enables investigation into its effects on losses for a spatially-distributed asset such as pipelines in the specified geographic region.
