Recurrent Large Intraplate Earthquakes on the Jindabyne Thrust, Southeast Highlands, Australia
Description:
The recurrence characteristics of large intraplate earthquakes are poorly understood, leading to large uncertainties in seismic hazard assessments, particularly at the low annual probabilities of exceedance important to the design and maintenance of critical infrastructure. The southeast highlands of Australia have the greatest elevation and topographic relief of anywhere in the continent, relatively high seismicity rates, and a number of faults showing geomorphic evidence for neotectonic activity. The region also hosts major dam and hydroelectric infrastructure critical to Australia’s water and energy security. Despite this, no paleoseismic studies have previously been undertaken to characterise the earthquake potential of faults in the region.
We excavated four trenches on the more than 100 km long Jindabyne Thrust fault, and one trench on the 24 km long Hill Top Fault, which occurs in the hanging wall of the Jindabyne Thrust and is truncated by the thrust at its southern extent. Evidence for multiple large earthquakes was found on both faults, showing reverse displacement on the Jindabyne Thrust and strike-slip displacement on the Hill Top Fault. Trenches on the Jindabyne Thrust exposed a thick clay gouge zone within bedrock underlying the faulted alluvial sediments, and single-event displacements are on the order of 1.5 – 2.0 m. Optically stimulated luminescence dating of displaced alluvial and colluvial sediments is being used to constrain the timing of these earthquakes. The results demonstrate persistent recurrence of large surface-rupturing earthquakes on the Jindabyne Thrust over the Late Quaternary, implying a neotectonic component to range uplift in the south-eastern highlands, and an extant seismic hazard.
Session: Tectonics and Seismicity of Stable Continental Interiors - II
Type: Oral
Date: 5/3/2024
Presentation Time: 10:45 AM (local time)
Presenting Author: Jonathan
Student Presenter: No
Invited Presentation:
Authors
Jonathan Griffin Presenting Author Corresponding Author jonathan.griffin@ga.gov.au Geoscience Australia |
Dan Clark dan.clark@ga.gov.au Geoscience Australia |
Justine Kemp j.kemp@griffith.edu.au Griffith University |
Mark Stirling mark.stirling@otago.ac.nz University of Otago |
Tamarah King tamarah.king@ga.gov.au Geoscience Australia |
Olivia Kulesza okulesza@student.unimelb.edu.au University of Melbourne |
James La Greca j.lagreca@unimelb.edu.au University of Melbourne |
Ambica Sharma ambicas@student.unimelb.edu.au University of Melbourne |
Mark Quigley mark.quigley@unimelb.edu.au University of Melbourne |
Dee Ninis dee.ninis@src.com.au Seismology Research Centre, Melbourne, , Australia |
Tim Pietsch t.pietsch@griffith.edu.au Griffith University, Brisbane, , Australia |
Recurrent Large Intraplate Earthquakes on the Jindabyne Thrust, Southeast Highlands, Australia
Category
Tectonics and Seismicity of Stable Continental Interiors