Modern Reappraisal of Historical Seismicity for Seismic Hazard Assessment in Australia

A robust record of earthquake activity in any given region is vital to identify regions of elevated seismogenic potential, define seismogenic sources and to help forecast future rates of seismicity. Records of earthquakes predating instrumentation and those occurring while instrumentation was still in its infancy might be used to augment the relatively short duration of the instrumental era in Australia. The events occurring during these seismological eras are often termed “historical earthquakes”, and their study forms a valuable input for seismic hazard assessment. However, as with any scientific data, documentary evidence extracted from newspapers and other written materials is subject to uncertainties, incompleteness, and errors being repeated from a lack of a thorough modern re-examination of the available data. With application to seismic hazard in Australia, we revisit original sources to re-evaluate selected historical earthquakes such as the 1918 Queensland (QLD) and the 1954 Adelaide (SA) earthquakes. We discuss biases that impact the analyses of these and other historical earthquakes in Australia. Our study highlights the benefit of the critical evaluation of primary source materials to homogenise both archival and seismological materials, with modern observations, to improve our understanding of historical earthquakes in Australia. This will in turn will benefit future assessments of modern seismic hazard. Presented at the 2023 Australian Earthquake Engineering Society (AEES) National Conference