Seismotectonic setting

Definitions

The Australian continent lies completely within the Indo-Australian tectonic plate and is classified as a stable continental region (SCR) in terms of its tectonic setting and seismicity.5 SCR settings typically produce only approximately 0.2% of the Earth’s seismic moment release, however, large and potentially damaging earthquakes are not unusual (e.g.).6 For example, five earthquakes in Australia were sufficiently large to rupture the Earth’s surface have been documented in the last 40 years:

1968 Meckering Mw 6.5 earthquake in 130 km east of Perth7

1970 Calingiri Mw 5.9 earthquake, northeast of Perth8

1979 Cadoux Mw 6.1 earthquake, 165 kilometres northeast of Perth; second-most damaging earthquake in Western Australia9

1986 Marryat Creek Ms 5.8 earthquake in a remote northern part of South Australia10

1988 Tennant Creek Mw 6.6 earthquake near Tennant Creek in the Northern Territory in11

The neotectonic domains identified by Clark et al.12 are generally consistent with the major tectonic units that make up Australia13 and broadly subdivide into cratonic and non-cratonic terranes. These domains characterise the behaviour of faults that are considered to have hosted large earthquakes in the current stress regime (i.e. within the last 10-5 Myr;).14 The cratonic terranes comprise Precambrian cratons and reactivated Proterozoic crust of western and central Australia. The non-cratonic terranes consist of Phanerozoic accretionary crust and Mesozoic basins of eastern Australia ( Figure 1). The continent is almost completely bounded by passive margin extended continental crust.15

Gruyere is situated within the eastern most known greenstone belts of the Archaean Yilgarn Craton (Figure 2), the Yamarna and Dorothy Hills Greenstone Belts. Mineralisation at Gruyere is an orogenic gold deposit of Archaean age located on a flexure point of the regional scale Dorothy Hills Shear Zone where the shear zone changes from a northerly direction to a NNW direction. Gold mineralisation is hosted within the steep easterly dipping Gruyere Porphyry (Pennington Scott, 2017). The Gruyere TSF is located on an area underlain by basalt that is mantled by highly to moderately weathered rock.

Neotectonic domains model for Australia [@Clark2011;@Clark2012]

Figure: 1: Neotectonic domains model for Australia16

Tectonic and geological setting of the Yilgarn Craton, Western Australia. Approximate position of GGM indicated by black square (from [@PorteoGeo]

Figure: 2: Tectonic and geological setting of the Yilgarn Craton, Western Australia. Approximate position of GGM indicated by black square (from17

Earthquake data

Several seismic networks have operated throughout Australia ranging in scale from local infrastructure monitoring networks (e.g.)18 to the Australian National Seismic Network (ANSN).19 The ANSN was substantially upgraded following the Sumatra–Andaman Mw 9.3 earthquake on 2004 December 26, resulting in a devastating tsunami. The overall network sensitivity of the ANSN is currently seismic magnitude ≥ 3, indicating that all magnitude 3 and above events across the continent will be reliably located.20 The network sensitivity has been far lower in the past. From 1920, events above magnitude 6 should have been reliably recorded. The sensitivity improved in 1959 to events above magnitude 5. Since 1990s, the threshold of completeness has been higher than magnitude 4.

The earthquake activity in Australia is widespread (Figure 3). While the largest recorded onshore event in the last century has not exceeded magnitude 7,21 the largest magnitude of historical earthquakes determined from neotectonic studies is magnitude 7.7. The largest energy release was the group of three events (Mw 6.2, 6.5 and 6.7) in just 12 hours near Tennant Creek in the Northern Territory (20°S, 135°E) in January 1988.22

Distribution of earthquake epicentres of M ≥ 3.0 from all available networks and known pre-instrumental observations (from [@Allen2020]

Figure: 3: Distribution of earthquake epicentres of M ≥ 3.0 from all available networks and known pre-instrumental observations (from23

Despite the relatively short historical record of seismicity relative to many regions worldwide and, in particular, relative to the return periods of large intraplate earthquakes (e.g.)24 persistent patterns in seismicity are evident in some regions (Figure 3).

In their 2020 paper, Allen et al.25 make the following observations:

Seismicity has remained relatively stationary in space and time in the historical era in the eastern highlands, the Flinders Ranges, and the northwest continental shelf region.26

Earthquake activity appears to have increased significantly in the Southwest Seismic Zone (SWSZ) of western Australia since the 1940s,27 where contemporary seismicity rates appear to exceed long-term averages based on Quaternary fault scarps.28 This suggests that the seismicity in the region is likely to be transient and migratory.29

The hypothesized migratory nature of seismicity in the SWSZ is consistent with the observation that none of the faults relating to the nine historical surface rupturing earthquakes in Australia were identified and mapped using topographic signature prior to the causative historical events.30 Therefore, large up to M = 7.631 earthquakes could occur anywhere, and in unanticipated locations throughout the Australian crust (e.g.).32

Note that the absence of seismic events does not necessarily imply that future earthquakes are not possible. For example, prior to 1987, the region around Tennant Creek had no known seismicity. Activity started with two magnitude 5 events, followed by the group of Mw 6 events and a lengthy sequence of aftershocks.33 Since the return period for intracontinental earthquakes can be very long, e.g. over 10,000 years from trenching evidence at Tennant Creek, the historical record needs to be supplemented with information from neotectonic studies.34

Interestingly, the depth of the earthquakes in Australia is generally quite shallow, with events rarely initiating deeper than 12 km and propagating to the surface.35

Earthquake spatial distribution

The seismicity patterns are well described in Kennett et al.36 and are quoted here verbatim.

A small cluster of events occurs in the southern Tasman Sea (40°S, 155°E) which is close to the location where the projection of the Tasmantid seamount chain would occur, as a consequence of the northward movement of the Australian plate over a fixed hotspot.

A relatively tight band of seismicity occurs through the Adelaide Fold Belt and the Flinders Ranges, with many events at greater depth than is common elsewhere across the continent. This belt of earthquakes may well link to the Simpson Desert, where a number of larger events occurred in the 1940s.

Through central Australia, most events reflect a compressive regime associated with the ongoing collision of Australia with the Pacific Plate to the north. In recent years there have been a number of sizeable events aligned roughly east–west from the Musgrave towards Yulara. The detailed study of Bowman37 for the Tennant Creek events to the north indicates the complexity of faulting and differences between nearby faults. Such features are not readily captured in the summary centroid moment tensors that show an equivalent point source. Although most of the faulting at Tennant Creek was associated with south over north thrusting, a segment of the second fault to fail had the reverse behaviour. Surface faulting has also been found associated with the 1986 Marryat Creek event in northern South Australia and the 2016 Petermann Ranges event in the south of the Northern Territory.

A range of different styles of earthquake activity occurs in Western Australia. A concentrated zone of activity to the west of Perth has produced a number of events above magnitude 6 with distinct surface fault traces. This zone has a nearly north–south trend parallel near the eastern edge of the Yilgarn Craton. To the west, a zone of modest size events with a southwest to northeast orientation follows the edge of the Yilgarn Craton, linking into the Musgrave Province and the central Australian earthquake belt. A number of events have occurred in the fold belts surrounding the Kimberley Block in northwestern Australia, with a Mw 6.3 event near Derby WA in 1997. The trend of the King Leopold Belt towards the southeast leads into a distinct group of events that appears to be associated with continuing deformation at the northeastern margin of the Canning Basin. The western edge of this basin, where it meets the Pilbara Craton, is also marked by a modest number of events.

The western and northwestern margins of the Australian continent show a moderate amount of long-term activity. The events mostly lie close to the transition between thinned continental and oceanic crust. To the south the earthquakes lie much further offshore with ongoing activity along a belt close to 37°S.

The seismicity of the region is dominated by the earthquake activity associated with subduction along the Indonesian arc and in New Guinea. Strong and continuing activity occurs both in the subduction zone itself, and leading into the trench. Limited location accuracy for older events means that some of this activity on the seaward side of the subduction trench may be placed closer to Australia than their true locations.

Neotectonics

Geoscience Australia has made an enormous effort to assemble a database of neotectonic features across the continent (Figure 4) from a combination of remote sensing data, particularly digital elevation models, and field mapping. Where data is available, the database includes information such as fault length, neotectonic displacement, fault orientation, sense of movement, slip-rate, and large earthquake recurrence data. A small subset of features has been investigated paleoseismologically, however, most have been identified through geomorphic analysis of digital elevation data and have not been studied in detail.38

The features are rated where Class A have definite association with earthquake events, Class B are probable and Class C are possible.39 Many of the Class A and Class B neotectonic features are associated with long scarps that are much larger than those produced by any historic events – in such cases, multiple large earthquakes would be the likely cause. A zoomed in version of Figure 4 is shown in Figure 5. The black circle has a radius of 500 km from GGM and contains the neotectonic features of interest to this study.

Neotectonic features (yellow) downloaded from the Geoscience Australia website. Stress data (SHmax) is from the World Stress Map project [@Heidbach2018]

Figure: 4: Neotectonic features (yellow) downloaded from the Geoscience Australia website. Stress data (SHmax) is from the World Stress Map project40

Neotectonic fault scarps in Western Australia. Black circle has a 500 km radius around the Gruyere project site

Figure: 5: Neotectonic fault scarps in Western Australia. Black circle has a 500 km radius around the Gruyere project site

Regional stress field

The orientation of the maximum SHmax and minimum SHmin horizontal stress in the crust can be measured from a wide range of stress direction indictors. The Australian Stress Map project,41 and the ongoing efforts of the World Stress Map project,42 have collated a large number of stress indictors from various sources. The individual measurements are shown in Figure 5 and the overall regional trends are shown in Figure 6. The shallow stress state can be estimated from the orientation of breakout, drilling failures and the results of hydraulic fracturing, while earthquake focal mechanisms can be used to determine orientation of the deeper stresses (although there is the possibility that fault-planes may align with zones of pre-existing weakness rather than lie in the expected relation to the stress axis,).43 The present-day crustal stress pattern of the Australian continent is unlike all other major tectonic plates in that the stress pattern shows regional variability and it is not oriented sub-parallel to the direction of absolute plate motion of the Australian plate, which is NNE.44 The recent development of unconventional reservoirs in Australia, as well as conventional hydrocarbon and geothermal exploration has resulted in a greatly increased amount of new data for stress analysis. The number of stress data records has increased from 594 in 2003 to 2150 in 2016.45 The results shown in Figure 6 reveal four distinct regional trends for the SHmax orientation:

a NNE-SSW SHmax trend in northern and northwestern Australia,

a prevailing E-W orientation in most of western and south Australia,

orientation of SHmax in eastern Australia is primarily ENE-WSW,

orientation of SHmax of swings to NW-SE in southeastern Australia.46

Previous studies show that the complex stress pattern of the continent is controlled, at a first-order, by the superposition of plate tectonic forces exerted at the plate boundaries. However, models of the crustal stress pattern have not been able to simulate the stress pattern observed in eastern Australia, and have not addressed the numerous smaller scale variations in stress orientation.47 While there are no published stress measurements at GGM, the closest stress indictors show an approximately WNW SHmax direction in a compressive regime (Figure 6). This estimate is of low accuracy according to the World Stress Map’s quality rating system, which scales the length of the arrows according to accuracy. Therefore, we prefer to estimate the horizontal stress directions interpolation from 7 as this shows the trends of the high accuracy data. According to 7, the SHmax direction is approximately WSW.

Australian stress map regional indicators [@Rajabi2017].  The length of the lines indicates the quality and reliability of SHmax orientations according to the World Stress Map quality-ranking scheme. The approximate position of GGM is shown by the red square

Figure: 6: Australian stress map regional indicators.48 The length of the lines indicates the quality and reliability of SHmax orientations according to the World Stress Map quality-ranking scheme. The approximate position of GGM is shown by the red square

Maximum horizontal stress orientations based on Australian stress map data (from Hillis and Reynolds, 2003).

Figure: 7: Maximum horizontal stress orientations based on Australian stress map data (from Hillis and Reynolds, 2003).

Local faults and shear zones (within 40 km)

Dorothy Hills and Yamarna shear zone

GGM lies on a regional shear zone, known as the Dorothy Hills shear zone, which extends along the entire length of the greenstone belt (Figure 8). Aeromagnetic data indicates that the NNW trending segments of the shear zone are subparallel to regional stratigraphy, whilst the north-south segment is transgressive.49 The kinematic indicators within the shear zone show sinistral, dextal, reverse and normal sense of displacement, suggested a complex structural history50 with a changing stress field. While this shear zone is ancient and is not incorporated into the neotectonics database hosted by Geoscience Australia, it has a similar orientation to the nearly neotectonics faults and is a zone of weakness along which slip could occur.

Location and geology of the Yamarna Belt, showing the location of the Gruyere project on the Dorothy Hills Shear Zone [@Limited]

Figure: 8: Location and geology of the Yamarna Belt, showing the location of the Gruyere project on the Dorothy Hills Shear Zone51

A recent internal report52 reviewed frequency domain electromagnetic (FDEM) data collected around the TSF. FDEM is an active geophysical method where an artificial transmitter is used to induce electrical currents in subsurface conductors by electromagnetic waves generated at the surface. As the electromagnetic (EM) energy encounters different subsurface materials, eddy currents are induced, and secondary EM fields are generated. This secondary field is then recorded at the surface by a receiver loop. At the TSF site, an EM-34 system was used, allowing for horizontal component (HC) and vertical component (VC) readings. The VC measurements are generally shallower and in this case, for a 20 m dipole spacing, ~15 m deep and the deeper HC measurements are ~30 m deep. It is important, however, to note that the more conductive the overburden in an area is, the shallower the readings will be.

Figure 9 and Figure 10 show a conductive (red) feature, highlighted with a black outline, that is interpreted as a palaeochannel hosted in highly fractured bedrock up to a skin-depth of approximately 30 m. The orientation of this feature is orientated NNW and is likely related to the Dorothy Hills shear zone. Since the zone is conductive, the presence of water or seepage from the TSF is likely. This indicates that the fracture zone is open and thus favourably oriented concerning the regional stress field, therefore having the potential to slip.

EM34 HC results with overlain historical surface drainage (blue linework) (skin depth ~30 m) (satellite image source: ESRI World Map Online)

Figure: 9: EM34 HC results with overlain historical surface drainage (blue linework) (skin depth ~30 m) (satellite image source: ESRI World Map Online)

EM34 VC results with overlain historical surface drainage (blue linework) (skin depth ~15 m) (satellite image source: ESRI World Map Online)

Figure: 10: EM34 VC results with overlain historical surface drainage (blue linework) (skin depth ~15 m) (satellite image source: ESRI World Map Online)

The Yamarna Shear Zone, ~25 km southwest of the site, forms a broad zone of deformation, with strain partitioned into three main structural zones. The Mount Venn greenstone belt, forming the footwall to the west, preserves an early stage of approximately east–west oriented thrusting or extension (Figure 11). These structures were overprinted by upright folds and layer-parallel shearing, interpreted to represent a period of compressional to transpressional deformation indicating strike-slip shearing.53 The central and eastern zones are characterized by dextral and sinistral shearing, respectively. Both shear zones and surrounding seismic events downloaded from the Geoscience Australia seismic event data base are shown in Figure 12.

Simplified geology of the Yamarna Shear Zone overlain on the aeromagnetic image (1VD). The stereonets (a–f) are from the Mount Venn greenstone belt, (g) is from the central structural zone, and (h–k) are from the eastern structural zone. The fault solution ‘balls’ show the difference in stress regime between the central and eastern zones (σ1 is located in the black quadrant). Fault solutions for the dextral and sinistral domains are based on 4 and 12 points, respectively [@Pawley2007].

Figure: 11: Simplified geology of the Yamarna Shear Zone overlain on the aeromagnetic image (1VD). The stereonets (a–f) are from the Mount Venn greenstone belt, (g) is from the central structural zone, and (h–k) are from the eastern structural zone. The fault solution ‘balls’ show the difference in stress regime between the central and eastern zones (σ1 is located in the black quadrant). Fault solutions for the dextral and sinistral domains are based on 4 and 12 points, respectively.54

Seismic events surrounding site of interest.

Figure: 12: Seismic events surrounding site of interest.

NW trending thrust faults

In addition to the NNW trending Dorothy Hills Shear Zone, a set of NW striking thrust faults initially interpreted from magnetic data and changes in stratigraphy, is evident in Figure 8. Their orientations are normal to the strike of the DHSZ, do not match the orientations of the nearby recognised neotectonics faults, and are therefore not thought to be seismogenic. Table 4 records all the fault details, from the database of neotectonic features, within a 500 km radius from the site of interest (Figure 5).

Seismogenic source zones

A fault is considered active if it has hosted displacement under conditions imposed by the current Australian crustal stress regime, in the last 10-5 Ma, and hence may move again in the future.55 Similarly, neotectonic deformation is defined as deformation under conditions imposed by the current crustal stress regime.

The catalogue of active faults used varies in completeness, by the extent of unconsolidated sedimentary cover on the surface, the rate of landscape processes relative to the rate of tectonic processes, etc. The catalogue is most complete in the southwest of Western Australia where most surface ruptures relating to greater than Mw 6.5 earthquakes having occurred in the last 100ka are represented.56 Australia may be divided into several domains which are distinguished by differing active fault characteristics related to the gross geologic setting as shown in Figure 13. In general, known active fault density is low in the Western and Central and Nullarbor domains, high in the Flinders/Mt Lofty Ranges Domain, and intermediate in the Eastern Australia domain. Neotectonic displacements on active faults are in the order of ten metres or less in the Western and Central Domain, less than a few tens of metres in the Nullarbor Domain, and up to a couple of hundred metres in the Flinders/Mt Lofty and Eastern Australia domains. Faults longer than 50 km occur in each domain, suggesting that earthquakes of greater than Mw 7.0 are possible Australia-wide.57

Preliminary neotectonic source domains [@clark2006seismic]

Figure: 13: Preliminary neotectonic source domains58

The site of interest lies within the Western and Central domain, where earthquake recurrence appears to be highly temporally clustered and events being separated by several tens of thousands of years, and prevailing dormant periods lasting hundreds of thousands to millions of years.59

Earthquake scenarios

From the faults within 250 km to the project site, the ones that are either favourably oriented with respect to the stress field or part of the neotectonic database were selected as the potentially seismogenic faults for deterministic seismic hazard assessment. The maximum instrumented magnitud, maximum moment magnitude, fault type, strike direction and length, dip angle and minimum horizontal distance to site for each fault are detailed in Table 5. The information is obtained using Geoscience Australia online tools: the Neotectonic Features database and the research code and input data for the 2018 revision of Australia’s National Seismic Hazard Assessment (NSHA18). For the two closest faults (Dorothy and Yamarna) a magnitude corresponding to a fault length around 2.5 km using Leonard60 fault-scaling relation. This is subject to appearence of neotectonic evidence indicating the possible extent of a fault in the vicinity of GMM.


  1. Dan Clark, Andrew McPherson, and Russ Van Dissen, “Long-Term Behaviour of Australian Stable Continental Region (SCR) Faults,” Tectonophysics 566 (2012): 1–30; AC Johnston, “Seismotectonic Interpretations and Conclusions from the Stable Continental Regions,” The Earthquakes of Stable Continental Regions: Assessment of Large Earthquake Potential, 1994, 1–368; M Leonard et al., “The Challenges of Probabilistic Seismic-Hazard Assessment in Stable Continental Interiors: An Australian Example,” Bulletin of the Seismological Society of America 104, no. 6 (2014): 3008–28; Saskia M Schulte and Walter D Mooney, “An Updated Global Earthquake Catalogue for Stable Continental Regions: Reassessing the Correlation with Ancient Rifts,” Geophysical Journal International 161, no. 3 (2005): 707–21.↩︎

  2. AJ Crone, MN Machette, and JR Bowman, “Episodic Nature of Earthquake Activity in Stable Continental Regions Revealed by Palaeoseismicity Studies of Australian and North American Quaternary Faults,” Australian Journal of Earth Sciences 44, no. 2 (1997): 203–14.↩︎

  3. FR Gordon, “The Meckering and Calingiri Earthquakes October 1968 and March 1970,” Geological Survey of Western Australia Bulletin, 1980.↩︎

  4. Gordon.↩︎

  5. JD Lewis et al., “The Cadoux Earthqauke (GSWA Report 11),” Perth, Australia, 1981.↩︎

  6. Michael N Machette, Anthony J Crone, and J Roger Bowman, Geologic Investigations of the 1986 Marryat Creek, Australia, Earthquake; Implications for Paleoseismicity in Stable Continental Regions, 2032-B, 1993; Crone, Machette, and Bowman, “Episodic Nature of Earthquake Activity in Stable Continental Regions Revealed by Palaeoseismicity Studies of Australian and North American Quaternary Faults.”↩︎

  7. Anthony J Crone, Michael N Machette, and J Roger Bowman, Geologica Investigations of the 1988 Tennant Creek, Australia, Earthquakes; Implications for Paleoseismicity in Stable Continental Regions, 2032-A, 1992; Crone, Machette, and Bowman, “Episodic Nature of Earthquake Activity in Stable Continental Regions Revealed by Palaeoseismicity Studies of Australian and North American Quaternary Faults.”↩︎

  8. “Australia’s Seismogenic Neotectonic Record” (Geoscience Australia Record, 2011).↩︎

  9. RD Shaw, P.. Wellman, and P.. Gunn, Guide to Using the Australian Crustal Elements Map (Australian Geological Survey Organisation, 1996).↩︎

  10. Richard R Hillis et al., “Present-Day Stresses, Seismicity and Neogene-to-Recent Tectonics of Australia’s ‘Passive’margins: Intraplate Deformation Controlled by Plate Boundary Forces,” Geological Society, London, Special Publications 306, no. 1 (2008): 71–90.↩︎

  11. Trevor I Allen et al., “The 2018 National Seismic Hazard Assessment of Australia: Quantifying Hazard Changes and Model Uncertainties,” Earthquake Spectra 36, no. 1_suppl (2020): 5–43.↩︎

  12. Clark, McPherson, and Collins, “Australia’s Seismogenic Neotectonic Record”; Clark, McPherson, and Van Dissen, “Long-Term Behaviour of Australian Stable Continental Region (SCR) Faults.”↩︎

  13. PorteoGeo, “Yilgarn Craton - Geology, Structure and Mineralisation,” n.d., http://www.portergeo.com.au/database/mineinfo.asp?mineid=mn1626.↩︎

  14. Wayne Peck, “An Earthquake Alarm and Situation Awareness Tool Developed for Areas of Low to Moderate Seismic Hazard: Recent Developments and Past Results,” in Australian National Committee on Large Dams/New Zealand Society of Large Dams Conference, Adelaide, South Australia, 2016.↩︎

  15. Mark Leonard, “One Hundred Years of Earthquake Recording in Australia,” Bulletin of the Seismological Society of America 98, no. 3 (2008): 1458–70; Kevin McCue et al., “Australia: Historical Earthquake Studies,” Annals of Geophysics, 2004.↩︎

  16. Brian Kennett, Richard Chopping, and Richard Blewett, The Australian Continent: A Geophysical Synthesis (ANU Press, 2018).↩︎

  17. Kennett, Chopping, and Blewett.↩︎

  18. Kennett, Chopping, and Blewett.↩︎

  19. Allen et al., “The 2018 National Seismic Hazard Assessment of Australia.”↩︎

  20. Clark, McPherson, and Van Dissen, “Long-Term Behaviour of Australian Stable Continental Region (SCR) Faults.”↩︎

  21. “The 2018 National Seismic Hazard Assessment of Australia.”↩︎

  22. Leonard, “One Hundred Years of Earthquake Recording in Australia.”↩︎

  23. Leonard.↩︎

  24. Mark Leonard and Dan Clark, “A Record of Stable Continental Region Earthquakes from Western Australia Spanning the Late Pleistocene: Insights for Contemporary Seismicity,” Earth and Planetary Science Letters 309, no. 3-4 (2011): 207–12.↩︎

  25. Leonard and Clark.↩︎

  26. Dan Clark and Trevor Allen, “What Have We Learnt Regarding Cratonic Earthquakes in the Fifty Years Since Meckering,” in Proc. Aust. Earthq. Eng. Soc. Conf, 2018, 16–18; Dan Clark and Mark Edwards, 50th Anniversary of the 14th October 1968 Mw 6.5 (Ms 6.8) Meckering Earthquake: Australian Earthquake Engineering Society Pre-Conference Field Trip Meckering, 15 November 2018 (Geoscience Australia, 2018).↩︎

  27. D Clark and M Leonard, “Regional Variations in Neotectonic Fault Behaviour in Australia, as They Pertain to the Seismic Hazard in Capital Cities,” in Australian Earthquake Engineering Society 2014 Conference, Nov 21-23, Lorne, Vic, 2014.↩︎

  28. JR Bowman, “The 1988 Tennant Creek, Northern Territory, Earthquakes: A Synthesis,” Australian Journal of Earth Sciences 39, no. 5 (1992): 651–69; Clark and Allen, “What Have We Learnt Regarding Cratonic Earthquakes in the Fifty Years Since Meckering”; Gordon, “The Meckering and Calingiri Earthquakes October 1968 and March 1970.”↩︎

  29. Kennett, Chopping, and Blewett, The Australian Continent.↩︎

  30. Kennett, Chopping, and Blewett.↩︎

  31. Kennett, Chopping, and Blewett.↩︎

  32. “The 1988 Tennant Creek, Northern Territory, Earthquakes.”↩︎

  33. Clark, McPherson, and Van Dissen, “Long-Term Behaviour of Australian Stable Continental Region (SCR) Faults.”↩︎

  34. Clark, McPherson, and Collins, “Australia’s Seismogenic Neotectonic Record.”↩︎

  35. Oliver Heidbach et al., “The World Stress Map Database Release 2016: Crustal Stress Pattern Across Scales,” Tectonophysics 744 (2018): 484–98.↩︎

  36. RR Hillis and SD Reynolds, “In Situ Stress Field of Australia,” SPECIAL PAPERS-GEOLOGICAL SOCIETY OF AMERICA, 2003, 49–58.↩︎

  37. Heidbach et al., “The World Stress Map Database Release 2016.”↩︎

  38. Kennett, Chopping, and Blewett, The Australian Continent.↩︎

  39. Charles DeMets, Richard G Gordon, and Donald F Argus, “Geologically Current Plate Motions,” Geophysical Journal International 181, no. 1 (2010): 1–80.↩︎

  40. M Rajabi et al., “Prediction of the Present-Day Stress Field in the Australian Continental Crust Using 3d Geomechanical–Numerical Models,” Australian Journal of Earth Sciences 64, no. 4 (2017): 435–54.↩︎

  41. Rajabi et al.↩︎

  42. Kennett, Chopping, and Blewett, The Australian Continent.↩︎

  43. Rajabi et al., “Prediction of the Present-Day Stress Field in the Australian Continental Crust Using 3d Geomechanical–Numerical Models.”↩︎

  44. Gold Road Resources Limited, “ASX Announcement, Gruyere Resource Increase to 5.62 Million Ounces,” n.d., https://www.openbriefing.com/AsxDownload.aspx?pdfUrl=Report/ComNews/20150916/01662100.pdf.↩︎

  45. Limited.↩︎

  46. Limited.↩︎

  47. AECOM, “TSF Seepage Recovery Network Refinement: Improvement Program Update 2021,” 2021.↩︎

  48. MJ Pawley et al., “The Yamarna Shear Zone: A New Terrane Boundary in the Northeastern Yilgarn Craton,” Geological Survey of Western Australia, Annual Review 2008 (2007): 26–32.↩︎

  49. Pawley et al.↩︎

  50. Dan Clark, “A Seismic Source Zone Model Based on Neotectonics Data,” Earthquake Engineering in Australia, 2006, 69–76.↩︎

  51. Clark.↩︎

  52. Clark.↩︎

  53. Clark.↩︎

  54. Clark.↩︎

  55. “Self-Consistent Earthquake Fault-Scaling Relations: Update and Extension to Stable Continental Strike-Slip Faults,” Bulletin of the Seismological Society of America 104, no. 6 (2014): 2953–65.↩︎