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

Prior to the advent of satellite imagery in the 1970s, extensive use was made of aerial photography to systematically image and capture land information. As part of national mapping and survey campaigns run by its predecessors, Geoscience Australia (GA) is custodian of some 1.2 million aerial photos dating back to 1928. Through these campaigns every part of Australia and its external territories was imaged at some point and often repeatedly over the last 90 years, forming a unique and invaluable historical collection. Most importantly, they enable us to extend the record of surface land changes back an additional 50 years or more. GA is progressively moving this collection from analogue to a modern digital data management framework. Discoverability and access to data are essential to realising the full potential of the collection, and associated flight line diagrams are critical in connecting physical and digitised material in the collection to an accurate location consistent with modern datums. The focus of digitisation has been on scanning film and storing individual frames as photo images. Both flight line diagrams are also being digitised and georeferenced, and information on the film is transcribed into a structured database, which will drive a future catalogue for open online access. Only a subset of the aerial photos have been digitised, based on preservation concerns and specific use-cases. GA also is prototyping a new processing workflow to value-add to the digitised collection by creating products that are readily consumable into geographic information systems and as web services. This work may lead to further investment in digitisation by demonstrating broader utility and continuing collaboration with other stakeholders such as the National Archives of Australia. This will be needed to complete the modernisation vision, As with other historic data remediation, surprising finds have been unearthed, gaps in supporting information identified, and an untapped but largely recognised desire for the data. GA is investigating possible applications of citizen science to aid in the modernisation of this collection. This presentation will look at the process undertaken, the type of data available, and will outline some examples of the data, and future use. <b>ePoster is no longer available for access</b>

Historical reports of earthquake effects from the period 1681 to 1877 in Java, Bali and Nusa Tenggara are used to independently test ground motion predictions in Indonesia’s 2010 national probabilistic seismic hazard assessment (PSHA). Assuming that strong ground motion occurrence follows a Poisson distribution, we cannot reject Indonesia’s current PSHA for key cities in Java at 95% confidence. However, the results do suggest that seismic hazard may be underestimated for the megacity Jakarta. Ground motion simulations for individual large damaging events are used to identify plausible source mechanisms, providing insights into the major sources of earthquake hazard in the region and possible maximum magnitudes for these sources. The results demonstrate that large intraslab earthquakes have been responsible for major earthquake disasters in Java, including a ~Mw 7.5 intraslab earthquake near Jakarta in 1699 and a ~Mw 7.8 event in 1867 in Central Java. The results also highlight the potential for large earthquakes to occur on the Flores Thrust. We require an earthquake with Mw 8.4 on the Flores Thrust to reproduce tsunami observation from Sulawesi and Sumbawa in 1820. Furthermore, large shallow earthquakes (Mw > 6) have occurred in regions where active faults have not been mapped identifying the need for further research to identify and characterize these faults for future seismic hazard assessments. <b>Citation:</b> Jonathan Griffin, Ngoc Nguyen, Phil Cummins, Athanasius Cipta; Historical Earthquakes of the Eastern Sunda Arc: Source Mechanisms and Intensity‐Based Testing of Indonesia’s National Seismic Hazard Assessment. <i>Bulletin of the Seismological Society of America </i>2018; 109 (1): 43–65. doi: https://doi.org/10.1785/0120180085

Geoscience Australia’s Historical Aerial Photography Program currently involves scanning and georeferencing old flight diagrams to enable the digitising and positioning of historical aerial photographs for easy discovery and download. Accurate digital mapping of GA’s aerial photography collection will make catalogue searches easier and the collection more accessible to the public. This story map presents an interactive history of aerial photography, a background of aerial photography in Australia, historical aerial photography use cases and scenarios, and a background on Geoscience Australia's program to digitise flight diagrams and create a catalogue of aerial photographs.