Knowledge of the nature of buildings within business precincts is fundamental to a broad range of decision making processes, including planning, emergency management and the mitigation of the impact of natural hazards. To support these activities, Geoscience Australia has developed a building information system called the National Exposure Information System (NEXIS) which provides information on buildings across Australia. Most of the building level information in NEXIS is statistically derived, but efforts are being made to include more detailed information on the nature of individual buildings, particularly in business districts. This is being achieved in Adelaide through field survey work.

<div>In mid-2022 two paleoseismic trenches were excavated across the Willunga Fault at Sellicks Hill, ~40 km south of Adelaide, at a location where range front faulting displaces a thick colluvial apron, and flexure in the hanging wall has produced an extensional graben. Vertical separation between time-equivalent surfaces within the Willunga Embayment and uplifted Myponga Basin indicate an average uplift rate of 40 m/Myr since 5 Ma across the Willunga fault at the trench location, equivalent to a slip rate of 57 m/Myr across a 45° dipping fault. </div><div> The field sites preserve evidence for at least 4-5 large earthquake events involving approximately 6.9 m of discrete slip on fault planes since the Mid to Late Pleistocene. If the formation of red soil marker horizons in the trenches are assumed to relate to glacial climatic conditions then a slip-rate of 26-46 m/Myr since the Mid Pleistocene is obtained. These deformation rate estimates do not include folding in the hanging wall of the fault, which is likely to be significant at this site as evidenced by the existence of a pronounced hanging wall anticline. In the coming months, the results of dating analysis will allow quantitative constraint to be placed on earthquake timing and slip-rate, and a structural geological study seeks to assess the proportion of deformation partitioned into folding of the hanging wall.</div><div> The 2022 trenches represent the most recent of ten excavated across this fault. Integration of the 2022 data with those from previous investigations will allow fundamental questions to be addressed, such as whether the Willunga fault ruptures to its entire length, or in a segmented fashion, and whether any segmentation behaviour is reflected in local slip-rate estimates. Thereby we hope to significantly improve our understanding of the hazard that this, and other proximal Quaternary-active faults, pose to the greater Adelaide conurbation and its attendant infrastructure.</div> This paper was presented to the 2022 Australian Earthquake Engineering Society (AEES) Conference 24-25 November (https://aees.org.au/aees-conference-2022/)

<div>This data package contains interpretations of airborne electromagnetic (AEM) conductivity sections in the Exploring for the Future (EFTF) program’s Eastern Resources Corridor (ERC) study area, in south eastern Australia. Conductivity sections from 3 AEM surveys were interpreted to provide a continuous interpretation across the study area – the EFTF AusAEM ERC (Ley-Cooper, 2021), the Frome Embayment TEMPEST (Costelloe et al., 2012) and the MinEx CRC Mundi (Brodie, 2021) AEM surveys. Selected lines from the Frome Embayment TEMPEST and MinEx CRC Mundi surveys were chosen for interpretation to align with the 20&nbsp;km line-spaced EFTF AusAEM ERC survey (Figure 1).</div><div>The aim of this study was to interpret the AEM conductivity sections to develop a regional understanding of the near-surface stratigraphy and structural architecture. To ensure that the interpretations took into account the local geological features, the AEM conductivity sections were integrated and interpreted with other geological and geophysical datasets, such as boreholes, potential fields, surface and basement geology maps, and seismic interpretations. This approach provides a near-surface fundamental regional geological framework to support more detailed investigations. </div><div>This study interpreted between the ground surface and 500&nbsp;m depth along almost 30,000 line kilometres of nominally 20&nbsp;km line-spaced AEM conductivity sections, across an area of approximately 550,000&nbsp;km2. These interpretations delineate the geo-electrical features that correspond to major chronostratigraphic boundaries, and capture detailed stratigraphic information associated with these boundaries. These interpretations produced approximately 170,000 depth estimate points or approximately 9,100 3D line segments, each attributed with high-quality geometric, stratigraphic, and ancillary data. The depth estimate points are formatted for compliance with Geoscience Australia’s (GA) Estimates of Geological and Geophysical Surfaces (EGGS) database, the national repository for standardised depth estimate points. </div><div>Results from these interpretations provided support to stratigraphic drillhole targeting, as part of the Delamerian Margins NSW National Drilling Initiative campaign, a collaboration between GA’s EFTF program, the MinEx CRC National Drilling Initiative and the Geological Survey of New South Wales. The interpretations have applications in a wide range of disciplines, such as mineral, energy and groundwater resource exploration, environmental management, subsurface mapping, tectonic evolution studies, and cover thickness, prospectivity, and economic modelling. It is anticipated that these interpretations will benefit government, industry and academia with interest in the geology of the ERC region.</div>