Melbourne CBD Case Study: URM Retrofit Effectiveness in Avoiding Mass Casualties

Earthquakes occur without warning and human mobility during strong shaking is difficult. This has implications for casualty outcomes from such rapid onset events. Unreinforced masonry (URM) in particular presents a great risk in the high pedestrian exposure precincts of major cities. Surveys of major Australian cities have indicated that almost half of the central business district (CBD) buildings by number are of older URM construction and have elements that could fall onto pedestrians in a major shake. With a focus on the greater CBD of Melbourne, this risk and mitigation options for it have been studied. In a case study undertaken as part of the Bushfire and Natural Hazards CRC (BNHCRC), the casualties, damage and broader economic consequences of a major earthquake in central Melbourne have been modelled. This research directly utilised BNHCRC vulnerability research on URM by the authors and separate work by Geoscience Australia on modelling human exposure in a major business precinct. Through a virtual retrofit of the high risk URM buildings the benefits of retrofit were demonstrated. In particular, the prioritising of areas of high human exposure in a manner similar to that being used in New Zealand was found to achieve greater reductions of injuries. Abstract submitted to / presented at the 2022 Australian Earthquake Engineering Society (https://aees.org.au/aees-conference-2022/)