b'NewsGeophysics in the surveyswithin this category have been identifiedKennett, B. L. N., A. Gorbatov, H. Yuan, S.Miller, M. S., R. Pickle, R. Murdie, H. Yuan, T. I. and are currently undergoing re- Agrawal,R. Murdie, M. P. Doublier, C. M. Eakin, M.Allen,K. Gessner, B. L. N. Kennett and J. Whitney, deployment to address these concerns. S. Miller, L. Zhao, K. Czarnota, J. P. ODonnell, M.2023. Southwest Australia Seismic Network Dentith and K. Gessner, 2023. Refining the Moho(SWAN): Recording Earthquakes in Australias Figure 3 illustrates the preliminaryacross the Australian continent, GeophysicalMost Active Seismic Zone, Seismological crustal discontinuity structure, such asJournal International, 233: 1863-77. ResearchLetters.the Moho, modelled through seismicMartin, D.M.C.B., R. Murdie, D. E. Kelsey, R.Quentin de Gromard, R., T.J. Ivanic and I. Zibra, receiver function stacking using dataQuentin de Gromard, C.M. Thomas, H.N. Cutten,Y.2021. Pre-Mesozoic interpreted bedrock geology from the first six months of phase 1Zhan, Y. Lu, P.W. Haines and J. Brett, 2022.of the southwest Yilgarn, 2021, in Accelerated data. Three cross-sections follow deepCompilation and geological implications of theGeoscience Program extended abstracts seismic reflection survey 23GSWA- major crustal boundaries map and 3D model ofcompiled by Geological Survey of Western SW1 profile (GSWA, 2024), and twoWestern Australia, Geological Survey of WesternAustralia: Geological Survey of Western Australia arbitrary lines across southwesternAustralia Record, 2022/7: 49. Record 2021/4, p.122144.WA. Notably, the primary feature, the Moho interface, is clearly observed between depths of 30and 50 km along these cross-sections,except acrossa) PERTHDarling SOUTH WEST TERRANE Corrigin Tectonic YOUANMITERRANEBASIN Fault Youanmithe Darling Fault. These initial findings0 Zone Shear Zone 0.04align closely with the refined AusMoho10 0.02Depth(km)20model (Kennett et al. 2023), which30 AusMoho 2023 040 -0.02utilised seismic data from pre-WA Array50 Receiver functionstack - velocity gradient-0.0460deployments over the past decades.0 50 100 150 200 250 300 350 400 450 500 55023GSWA-SW1 line distance from SW (km)However, the WA Array data addsPERTHDarlingb) Fault SOUTH WEST TERRANE YOUANMI TERRANEYouanmisignificant detail, for example imbricatedBASIN Corrigin Tectonic Shear ZoneMoho, laterally varying Moho strength0 Zone 0.0410and double-Moho, demonstrating20 0.02Depth (km)30 0strong correlation with the complex local40 AusMoho 2023 -0.02surface geology. 50 Receiver functionstack - velocity gradient-0.04600 50 100 150 200 250 300 350 400 450 500 550 600The second phase of WA Array has beenDarling Blue line distance from SW (km) ALBANYFaultin the ground since February-Marchc) PERTHSOUTH WEST TERRANE FRASER OROGENBASIN2024, in a region bordering the east0 CorriginTectonicZone 0.04and north of the phase 1 area. This10 0.02Depth (km) 20 AusMoho 2023expansionextends from Geraldton30 0acrossto Leonora and Laverton and40 -0.0250down through the Goldfields to60 Receiver functionstack - velocity gradient-0.040 50 100 150 200 250 300 350 400 450 500 550 600Esperance. Looking forward, the thirdGreen line cistance from NW (km)phase of WA Array is scheduled for deployment in May 2025, in the centralFigure 3. Provisional receiver function common-conversion-point (CCP;Dueker and Sheehan 1997) east of Western Australia. This remotestacking model along the three cross-sections shown in Figure 1a), along deep seismic reflection survey region poses logistical challenges,23GSWA-SW1, b), blueline, and c), green line. The CCP model reflects shear wave velocity gradientswith requiring access to sites by helicopterrespect to depth. White dashed lines define the Moho interface from the refined AusMoho model and significant efforts from ground(Kennettetal., 2023).crews. Negotiations with traditional owners are currently underway, aimingTable 1. WA Array phase 1 sensor and digitisercombinations.tosecure mutually agreeable locations for deployment. Pair_code Seismometer Digitiser No. stationsHuaiyu Yuan, Reza Ebrahimi,1 Reftek colt60 Reftek WRANGLER 6RuthMurdie, John Paul ODonnell,2 Reftek colt120 Reftek WRANGLER 29Simon Johnson, Raphael Quentin de Gromard and Klaus Gessner 3 GaiaCode Theta Guralp MINIMUS 16E Huaiyu.YUAN@dmirs.wa.gov.au 4 Silicon Audio 213-120PA SRC GECKO 295 Trillium Compact 120 Guralp MINIMUS 11References 6 Trillium Compact 120 ANU LPR-200 20Dueker, K. G., and A. F. Sheehan, 1997. Mantle7 Trillium Compact 120 ANU TerraSAWR 14discontinuity structure from midpoint stacks of8 Trillium Dome 120PA Reftek130S 25converted P and S waves across the Yellowstone hotspot track, J. Geophys. Res., 102: 8313-27.9 Trillium Dome 120PA Nanometrics Taurus 12GSWA, 2024. GSWA Southwest-Midwest deep10 Trillium postholeANU TerraSAWR 3crustal seismic survey 2023-2024, Line 23GSWA- 11 6TD (30 sec) Guralp 6TD 1SW1 (MAGIX registration number 72447).https://magix.dmirs.wa.gov.au/surveys/Note: WA Array phase 1 stations have been categorised based on their assigned instrument pair numbers, as detailed here, view-survey/3806 which outlines station categories according to instrumentation and the number of stations within each category.24 PREVIEWJUNE 2024'