Quality Control of 40 Years of Passive Seismic Data in Australia and Its Impact on Seismic Discontinuities, Velocity Variations, and Anisotropy Measurements

Seismic imaging techniques are essential for investigating Earth's structure, providing insights into geological and geodynamic processes. The accuracy of these methods relies on proper seismic instrument deployment, sensor performance, and long-term data maintenance. To ensure reliable results, rigorous quality assurance and quality control (QA/QC) procedures are necessary, including instrument orientation correction, GPS clock drift adjustments, and metadata verification. In this study, we conduct an extensive QA/QC assessment of passive seismic data collected over the past 40 years from temporary deployments in Australia (https://auspass.edu.au/), the Australian National Seismograph Network (ANSN), and the AusArray network (https://www.eftf.ga.gov.au/ausarray). AusArray, initially funded through the Exploring for the Future program continues with an expanded deployment as part of the Resourcing Australia's Prosperity initiative. We demonstrate how QA/QC improvements enhance the accuracy of noise correlation functions in ambient noise tomography and how instrument orientation corrections refine anisotropy measurements from shear-wave (SKS) splitting. Additionally, we assess the impact of data quality on detecting seismic discontinuities, including the Moho, lithospheric boundaries, and mantle transition zone discontinuities (410 km and 660 km). Our preliminary results show how improved data integrity leads to better constraints on seismic velocity variations and anisotropy across Australia, revealing key features of the lithosphere and upper mantle. By systematically addressing quality control issues, this study underscores the critical role of QA/QC in refining seismic models and advancing our understanding of the Australian continent’s deep structure. Presented at the 2025 IAGA/IASPEI Joint Scientific Meeting