The L210 South Nicholson 1096 km-long deep seismic reflection lines were acquired from 6 June to 14 August, 2017. The survey involved the acquisition of seismic reflection and gravity data along five traverses, 17GA-SN1 (375 km), 17GA-SN2 (213 km), 17GA-SN3 (58 km), 17GA-SN3 (98 km), and 17GA-SN5 (352 km). The South Nicholson seismic survey was undertaken in collaboration with and funded by: The energy theme in Geoscience Australia - Exploring for the Future; Northern Territory Geological Survey (NTGS); Department of Natural Resources and Mines - through the Geological Survey of Queensland (GSQ); and AuScope. <b>Raw data for this survey are available on request from clientservices@ga.gov.au - Quote eCat# 116881</b>

<div>The Central Australian Basins 2D Seismic Reprocessing Project is an initiative under Geoscience Australia's "Australia’s Future Energy Resources" (AFER) program, funded by the Australian Government through the "Exploring for the Future" (EFTF) program. The project aims to assess the untapped resource potential of selected underexplored onshore sedimentary basins in terms of natural gas, oil, and groundwater, while also investigating opportunities for geological storage of carbon dioxide and hydrogen. By providing pre-competitive data, the initiative seeks to stimulate investment in mineral, energy, and groundwater exploration.</div><div>&nbsp;</div><div>This project focuses on improving the understanding of the geological evolution and relationships among various Australian basins, ranging from the early Paleozoic Amadeus, Warburton and Adavale basins to the Permian-Triassic Pedirka, Simpson, northern Cooper and southern Galilee basins, and the Jurassic–Cretaceous western Eromanga Basin. To achieve this, modern seismic processing techniques were applied to 33 selected multi-vintage legacy lines with a total length of approximately 2,100 km, enhancing the resolution and image quality of the seismic lines. The dataset includes deep crustal as well as shallow lines from Queensland and South Australia. The data were collected using various acquisition sources such as Vibroseis, Geoflex, and dynamite. Six merged lines were also created to aid in interpretation.</div><div>&nbsp;</div><div>Both stacks and gather data are provided in SEG-Y format, along with navigation data, velocity, and statics. The reprocessing focused on enhancing seismic reflectors and faults, attenuating noise, and optimising frequency content for target depths. Techniques used in the reprocessing include creating a 3D static model, noise attenuation methods, minimum phasing of the Vibroseis data to match dynamite lines, surface-consistent deconvolution, and building a precise velocity model for optimising pre-stack time and depth migration.</div><div><br></div><div><strong>Processed gather data&nbsp;for this survey are also available on request from clientservices@ga.gov.au - Quote eCat# 148931</strong></div>

<div>The active seismic and passive seismic database contains metadata about Australian land seismic surveys acquired by Geoscience Australia and its collaborative partners. </div><div>For active seismic this is onshore surveys with metadata including survey header data, line location and positional information, and the energy source type and parameters used to acquire the seismic line data. For passive seismic this metadata includes information about station name and location, start and end dates, operators and instruments. Each also contains a field that contains links to the published data. </div><div><br></div><div>The active and passive seismic database is a subset of tables within the larger Geophysical Surveys and Datasets Database and development of these databases was completed as part of the second phase of the Exploring for the Future (EFTF) program (2020-2024). The resource is accessible via the Geoscience Australia Portal&nbsp;(https://portal.ga.gov.au/), under 'Geophysics'. Use 'active seismic' or 'passive seismic' as search terms. </div><div><br></div>

<div>Ideally when combining different 3D seismic surveys differences in acquisition parameters warrant full pre-stack reprocessing from field data. However, there are occasions where this is not possible due to time, financial or data access constraints; a valuable alternative is post-stack merging and enhancement of existing migrations. The offshore Otway Basin was the subject of such a project, the objective of which was to produce a regularised and seamless 3D dataset of the highest possible quality, within a two-month turnaround time. The input migrated volumes varied by data extent, migration methodology, angle range and grid orientation. 14 input volumes totalling 8,092 km2 were post-stack merged and processed to produce a continuous and consistent volume, enabling more efficient and effective interpretation of the region. The surveys were regularised onto a common grid, optimised for structural trend, prior to survey matching. DUG’s mis-tie analysis algorithm, applied over a time window optimised for interpretation of key</div><div>events, was used to derive corrections for timing, phase and amplitude, using the Investigator North survey as a reference. This was followed by time-variant spectral and amplitude matching, with gain corrections applied, to improve continuity between volumes. Additional enhancements including noise removal and lateral amplitude scaling were also applied. The final merged volume offers significant uplift over the inputs providing better imaging of structure and event and dramatically improving the efficiency and quality of interpretation. This enables rapid reconnaissance of the area by explorers. Presented at the Australian Energy Producers (AEP) Conference & Exhibition

<div>The architecture of the lithosphere controls the distribution of thermal, compositional and rheological interfaces. It therefore plays a fundamental role in modulating key ore-forming processes including the generation, transport, fractionation, and contamination of melts.&nbsp;Recognition of its importance has led to renewed efforts in recent years to incorporate constraints on lithospheric structure into the targeting of prospective regions for mineral exploration. One example is a suggested relationship between the genesis of porphyry copper deposits – known to be associated with evolved, silica-rich magmas – and the thickness of the crust.&nbsp;Here, using a new compilation of spot measurements, we explore the utility of crustal thickness as an exploration tool for porphyry copper deposits.</div> This Abstract was submitted & presented at the 2022 American Geophysical Union (AGU) Fall Meeting 12-16 December (https://www.agu.org/Fall-Meeting-2022)

<div>One of the key challenges in assessing earthquake hazard in Australia is understanding the attenuation of ground-motion through the stable continental crust. There are now a small number of ground-motion models (GMMs) that have been developed specifically to estimate ground-motions from Australian earthquakes. These GMMs, in addition to models developed outside Australia, are considered here for use in the updated national seismic hazard assessment of Australia. An updated and extended suite of ground-motion data from small-to-moderate Australian earthquakes are used to assess the suitability of the candidate models for use in the Australian context. Recorded spectral intensities are compared with those predicted by the GMMs. Both qualitative and quantitative approaches are considered for such comparisons. The goodness-of-fit results vary significantly among different GMMs, spectral periods and distance ranges; however, overall, the Australian-specific GMMs seem to perform reasonably well in estimating the level of ground shaking for earthquakes in Australia. This paper was presented to the 2022 Australian Earthquake Engineering Society (AEES) Conference 24-25 November (https://aees.org.au/aees-conference-2022/)

In recent years there has been a considerable expansion of deployments of portable seismic stations across Australia, which have been analysed by receiver function or autocorrelation methods to extract estimates of Moho depth. An ongoing program of full-crustal reflection profiles has now provided more than 25,000 km of reflection transects that have been interpreted for Moho structure. The Moho dataset is further augmented by extensive marine reflection results. These new data sources have been combined with earlier refraction and receiver function results to provide full continental coverage, though some desert areas remain with limited sampling. The dense sampling of the Moho indicates the presence of rapid changes in Moho depth and so the Moho surface has been constructed using an approach that allows different weighting and spatial influence depending on the nature of the estimate. The inclusion of Moho results from gravity inversion with low weighting helps to resolve the continent-ocean transition and to provide additional control in the least sampled zones. The refined distribution indicates the presence of widespread smaller-scale variations in Moho structure. Strong lateral contrasts in crustal thickness remain, but some have become more subdued with improved sampling of critical areas. The main differences from earlier results lie in previously poorly sampled regions around the Lake Eyre Basin, where additional passive seismic results indicate somewhat thicker crust though still witha strong contrast in crustal thickness to the cratonic zone to the west. Appeared in Geophysical Journal International, January 2023

Following deep seismic reflection surveys on the Yilgarn and Pilbara cratons by Geoscience Australia with the Geological Survey of Western Australia and on the Superior Craton by the Canadian Lithoprobe program, these cratons are now some of the best surveyed Archean regions on Earth. We present seismic images that highlight how variations in crustal architecture relate to differences in Archean tectonic processes between cratons. All cratons are characterized by a mostly non-reflective 4–12 km-thick uppermost crust due to the presence of large granitoid plutons and gneissic domains. Localized regions of upper crustal seismic reflectivity are typically interpreted as supracrustal rocks and mafic sills or faults and shear zones. The middle and lower Archean crust contains variably complex geometries of relatively high amplitude reflections, though in some regions, such as the Eastern Goldfields Superterrane and the Abitibi Greenstone Belt, the lower crust appears less reflective than the middle crust. Crustal thicknesses vary from 30 km in the eastern Pilbara to 35–40 km across much of the Yilgarn and Superior, though thicknesses as great as 45–52 km occur locally in the latter two cratons. The characteristics of the Archean crust-mantle boundary, or Moho, which is commonly well-defined, differs between cratons, indicating significant variations in the tectonic processes that have driven the final stages of crustal evolution. Dipping reflections in the uppermost mantle linked to convergent crustal structures are interpreted as relict subduction scars. In the southern Superior Craton, Moho offsets and northdipping reflections in the middle and lower crust arose through successive underthrusting of Meso-Neoarchean island arcs, oceanic plateaux and microcontinental fragments, as they accreted against a pre-existing northern nucleus (e.g. North Caribou and Opatica terranes). Seismic reflection lines reveal a doubly vergent orogen above north-dipping mantle reflections that indicate subduction drive accretion. Post-orogenic crustal extension, which is inferred from crustal-scale normal shear zones and dropped greenstone belts, has not erased the original accretionary crustal architecture. In contrast, in the Yilgarn Craton interior, accretionary structures are less clear and there are no prominent offsets in the Moho. In the Youanmi Terrane, which represents the cratonic nucleus, a pervasive fabric of listric east-dipping mid-crustal reflections soles out into the upper part of subhorizontal lower crustal reflections. We interpret this reflective fabric to be the result of widespread crustal collapse during the late stage of craton evolution at c. 2.65–2.6 Ga that also produced subsidence of the upper crust. Though terrane boundaries can be identified in seismic data across the Eastern Goldfields Superterrane, these boundaries have commonly been modified by extension, which also overprinted any accretionary lower crustal structures, perhaps simultaneous with widespread intrusion of post-tectonic melts. Exhumation of moderately reflective, amphibolite to granulite facies crust in the Narryer Terrane above dipping mantle reflectors indicates that shortening along the northwestern edge of the Yilgarn Craton was subduction driven. In the eastern Pilbara Craton, shallowly dipping to subhorizontal reflections in the middle and lower crust preclude crustal-scale vertical tectonic movements and imply that the vertical displacements inferred from surface mapping were largely confined to the upper crust. <div>The abstract accompanies a talk the describes the architecture and and related tectonic processes of several Archean cratons based on reflection seismic interpretations. </div> This Abstract was submitted to & presented at the 2023 6th International Archean Symposium (6IAS) 25 - 27 July (https://6ias.org/)

<div><strong>Output Type:</strong> Exploring for the Future Extended Abstract</div><div><br></div><div><strong>Short Abstract: </strong>Knowledge of lithospheric structure is crucial information for resources exploration and deepening understanding of natural hazards. Available tomographic models of the Australian lithosphere often agree on large scale features, but in detail significant differences remain. Consequently, there is a growing need for a fully verifiable lithospheric model of Australia. Geoscience Australia has committed to develop such a model and share all results and datasets involved in model building. Here we present the first results of a full waveform inversion tomography model of Australia lithosphere down to a period of 70 s potentially able to resolve half wavelengths across continental Australia. Our model is based on seismic records from the National Seismic Network and legacy datasets with the addition of data from the currently deployed continental-scale 2° AusArray survey, which includes stations installed in previously inaccessible areas. We start with 193 earthquakes (moment magnitude (Mw) 6.2–7.5) and add 165 more earthquakes (Mw &gt;5.0) once the model progressed to a period of 70 s. Model resolution will improve over time as more data become available and more time is allowed for computation and quality control. As further iterations continue, and the inversion frequency range expands to higher frequencies, body waves can be exploited in full to constrain the model in detail and provide enough information for all components of the wavefield, building high-resolution tomographic models at a period of 40 s and below. Our model reveals previously observed first order features while revealing finer detail across much of continental Australia.</div><div><br></div><div><strong>Citation: </strong>Holzschuh, J., Gorbatov, A., Hejrani, B., Boehm, C. &amp; Hassan, R., 2024. Tomographic model of the Australian region from seismic full waveform inversion. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, https://doi.org/10.26186/149404</div>

<div><strong>Output type: </strong>Exploring for the Future Extended Abstract</div><div><br></div><div><strong>Short Abstract: </strong>Seismic tomography has been used for more than 50 years to map the seismic velocity structure of Earth’s interior. Here, we use data from the Exploring for the Future program, AusArray 2o deployment, to perform ambient noise tomography of the Australian continent. In this approach, stacks of cross-correlations of background seismic noise recorded by pairs of seismometers are employed to extract an approximation to the surface wave trains travelling between the seismometers. We have developed a semi-automatic approach to estimate dispersion properties of surface waves as a function of frequency at 0.01 – 1 Hz and deployed the largest ever network of broadband seismometers across the country to image the continental crust of Australia. In this study, we present an ambient noise tomography map of the Australian continent at 0.4 Hz (2.5 seconds), which is sensitive to the top 3 km of the Earth’s crust. Our model shows improved resolution across the country, for example, we observed a large low-velocity anomaly (~2.5 km/s) which delineates the shape of the entire Caning basin in Western Australia. This basin has never been imaged at this detail before, as previous tomographic studies do not measure surface wave velocity up to 0.4 Hz and do not have stations deployed in this area. The outcome demonstrates the utility of the ambient noise tomography method of imaging first-order features, that could be built upon for resource potential assessments.</div><div><br></div><div><strong>Citation: </strong>Hejrani B., Hassan R., Gorbatov A. & Zhao J., 2024. Towards continental-scale ambient noise tomography of Australia: a preliminary result from AusArray data. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, https://doi.org/10.26186/149637</div>