Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

230 1 2 T H I N T E R N AT I O N A L I N Q U A M E E T I N G O N PA L E O S E I S M O L O G Y , A C T I V E T E C T O N I C S A N D A R C H A E O S E I S M O L O G Y ( PATA ) , O C T O B E R 6 T H - 1 1 T H , 2 0 2 4 , L O S A N D E S , C H I L E PATA Days 2024 K E Y W O R D S © Commonwealth of Australia (Geoscience Australia) 2024 (1) Geoscience Australia, Canberra, Australia (2) Griffith University, Brisbane, Australia (3) University of Otago, Dunedin, New Zealand (4) University of Melbourne, Melbourne, Australia (5) Seismology Research Centre, Melbourne, Australia (6) Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia *Presenting author, Tamarah King *Email: tamarah.king@ga.gov.au Jonathan Griffin (1) Dan Clark (1) Justine Kemp (2) Mark Stirling (3) Tamarah King (1) * Olivia Kulesza (4) James La Greca (4) Ambica Sharma (4 ) Mark Quigley (4) Dee Ninis (5) Tim Pietsch (2) Bethany Eaton (4) Klaus Wilcken (6) LARGE EARTHQUAKE RECURRENCE IN THE SNOWY MONARO REGION: FIRST DATED HOLOCENE RUPTURE AND STRIKE-SLIP FAULT EVIDENCE FOR AUSTRALIA A B S T R A C T The Snowy Monaro region is home to major infrastructure critical to Australia’s energy and water security. The region also hosts a number of active faults capable of producing large earthquakes that may impact this infrastructure. However, to date the hazard and consequent risk from these faults has been poorly characterised. This study presents initial results of geological investigations to understand how often large earthquakes occur on these faults, and how big they may be, with a focus on the Jindabyne Thrust and the neighbouring Hill Top Fault. The investigation reveals at least three earthquakes on the Jindabyne Thrust, with the most recent event occurring within the Holocene. The investigation also demonstrates late Pleistocene activity of the Hill Top Fault. The new insights into earthquake activity rates have implications for our understanding of seismic hazard and risk in the Snowy Monaro region, and elsewhere in the southeast highlands of Australia. I N T R O D U C T I O N The southeast highlands of Australia have the greatest elevation and topographic relief of anywhere in the continent, relatively high seismicity rates, and are bound in the west by four identified neotectonic features, and in the east by six features (Australian Neotectonics Features Database (Geoscience Australia, 2024); Figure 1, Figure 2; see also Clark et al. (2016); Clark et al. (2017)).