b'NewsGeophysics in the surveysGeological Survey of Western Australia: Programme updatesWA Array seismic acquisitiontectonics, subsequent post-cratonisationscientific community and industry programmephase 1 evolution, and its current geological andpractitioners. Furthermore, these findings geophysicalcharacteristics. will be presented at various domestic and On July 1, 2022, the State GovernmentThe phase 1 deployment of WAinternational conferences and workshops of Western Australia (WA) announcedscheduled for the end of 2024, a state-wide passive-source seismicArray, led by the Geological Survey offostering collaboration and advancing acquisition programme, WA Array, withWestern Australia (GSWA), began ingeoscienceresearch.the purpose of mapping the entirelate November 2022, and concluded lithosphere of Western Australia. Asuccessfully in December 2023. DuringInitial processing of data quality grid pattern spaced at 40 km intervals,this phase, more than 160 stationsassurance and quality control (QA/comprising 160 stations per year, willwere strategically placed to cover theQC) (e.g., Figure 2) and provisional progressively cover the state oversouthwest corner of WA (Figure 1), alithospheric modelling (see Figure3) a period of ten years. WA Array isregion of particular geological interestindicate the success of phase 1 of WA primarily designed to investigate theand significance. Nearly ten terabytesArray. Figure 2 presents the power crustal and lithospheric mantle acrossof continuous seismic waveforms werespectral density of all eleven different various scales, promising a significantmeticulously archived throughoutsensor combinations (Table 1), which was advancement in our understanding ofthisperiod. initially hindered by sensor shortages WAs lithospheric architecture. Over theprior to the phase 1 deployment. coming decades, this knowledge willThis milestone marks the completionHowever, the spectral density curves of continuously provide a robust scientificof the first stage of data acquisition,WA Array sites generally fall within the basis for identifying prospective regionssetting the stage for subsequentlow- and high-noise bounds (indicated for mineral and energy exploration,phases. Currently, the acquired databy the bottom and top thick black lines, evaluating crucial land-use decisionsis undergoing rigorous processingrespectively), suggesting consistent to accommodate renewable energyand analysis. Scheduled for release inperformance of these stations throughout projects, contributing to the NationalDecember 2024, under the FDSN networkthe phase 1 deployment period. Notably, Seismic Hazard Assessment forcode WG and accessible through AusPass,theres discernible separation in station industrial infrastructure seismic risk,the Australian Passive Seismic Server,performance at longer periods among as well as informing building codes forthe phase 1 data will provide invaluablesome sensor/digitiser combinations. residential and commercial buildings.insights into the regions lithosphericAlthough the median noise levels of Crucially, the whole-lithosphericarchitecture. Anticipated lithosphericthese stations remain within acceptable models will offer direct insights intomodelling results from phase1 will bebounds, data from these stations for long our understanding of WAs lithosphere,detailed in forthcoming GSWA reports,periods could potentially impact the final spanning its early crustal-formingserving as a valuable resource for themodelling and interpretation.Stations 29S Youanmi Shear ZoneYOUANMI TERRANE WA ArrayPERTHOtherBASIN SWAN30SIda Fault31S EASTERNGOLDFIELDSSUPER- TERRANE32SDarling Fault Djerdacuttup FaultBlue line Corrigin Tectonic ZoneALBANYFRASER OROGEN33SLEEUWIN INLIERSOUTH WEST TERRANE Green Line23GSWA-SW1 line 34SltDunsborough FauALBANYFRASER OROGEN35S Figure 2. Median distribution of Power Spectral Density (PSD) based on Seismic Noise Probability Density Function analysis from the vertical 114E 115E 116E 117E 118E 119E 120E 121E component100 sample-per-second recordings of the WA Array seismic stationsin dB between 14 November 2022 and 5 December 2023. The thick Figure 1. WA Array Phase 1 (2022-2023) and other seismic network stationsblack lines denote Petersons New Low-Noise Model (NLNM) and New High-operated in southwest Western Australia, including SWAN (Miller et al. 2023)Noise Model (NHNM), serving as benchmarks that delineate the upper and and other temporary and permanent stations operated by the Australianlower limits of background seismic noise levels across varying frequency bands. National University and Geoscience Australia. Major crustal boundaries areThe alignment of the PSD curve with NHNM and NLNM curves is contingent from Martin et al. (2022); Corrigin Tectonic Zone from Quentin de Gromard et al.upon geological conditions, environmental factors, and instrumentation. (2021). Coloured solid lines with 100 km distance marks (white circles) show theThesemodels provide a crucial reference for understanding ambient noise locations of seismic cross-sections presented in Figure 3. levelswithin the Earths crust. JUNE 2024PREVIEW 23'