Consistent MMI area estimation for Australian earthquakes

Brief description

Geoscience Australia has been providing estimates of felt and potential damage radiuses for all earthquakes above magnitude 3.0 since 2002. Similarly, over the last decade, using the hazard modelling software EQRM, GA has produced scenario MMI maps for most Australian cities and several cities in our region. The former uses Empirical relations developed from measuring MMI III, IV, V and VI radiuses from the isoseismal map of ~150 Australian earthquakes. The later using various GMPEs to generate the hazard field and PGA/PGV to MMI conversions to estimate MMI. These two approaches have not previously been directly compared. We have tested the fit with between the empirical MMI areas and the scenario models for several combinations of GMPEs and PGA/PGV to MMI conversions. We also investigate the possible importance of site effects in biasing the empirical data, for which only the minimum and maximum epicentral distance was measured, particularly at low MMI. A scenario model that more accurately reflects the empirical data should be more robust than the current method, for both real-time earthquake advice and scenarios. It should also enable the conversions used to estimate the magnitude of pre-instrumental earthquakes to be tested. Additionally the GMPEs that give the best fit to the empirical data might provide guidance when selecting GMPES for PSHAs and future scenario products.

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Maintenance and Update Frequency: asNeeded

Statement: Unknown