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South West seismic zone

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The South West Seismic Zone (also identified as SWSZ) is a major intraplate earthquake province located in the south west of Western Australia.[1][2][3]

It was known earlier as the Yandanooka–Cape Riche Lineament,[4] including the physiographic boundary known as the Meckering Line, and also the junction between Swanland[clarification needed] and Salinaland[clarification needed].[5][6]

The zone exists within an Archaean Shield structure called the Yilgarn Block.[7] The identified geological subdivisions within this Precambrian structure do not show an obvious relation to the seismicity.[8]

The zone represents a significant seismic hazard to Perth.[2] More than six thousand earthquakes have occurred in the SWSZ in the years 1968 – 2002.[8] Meckering, Cadoux and Burakin earthquakes originated in the SWSZ. More recent events have occurred to the south in Lake Muir in 2018[9][10][11][12] and Arthur River in 2022.[13]

The zone and the explanation of it, has been titled Perthquake in the Catalyst programme on the ABC in 2001.[14]

Temporal variation of the events in the region have been analysed over time.[15][16] In the 2000s, monitoring and instrumentation was developed in the region.[17][18]

Table of earthquakes

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List of earthquakes of magnitude 4 or more in Southwestern Australia 1920–1961 (based in part on the records of Perth Observatory 1923–1959 and Mundaring Geophysical Observatory 1959–1980).[19]

Date Origin time Epicentre
(lat., S) 		Epicentre
(long., E) 		Local magnitude Location
8 February 1920 05:24 35.00 111.00 6.2 260 km south west of Cape Leeuwin
18 December 1940 21:45 32.20 117.20 4.2 Beverley, Brookton
19 April 1946 21:13 38.5 114.5 5.7 West of Yallingup
17 September 1946 15:12 32.5 116.9 4.5 Pingelly
2 May 1949 10:00 30.90 116.40 5.1 Yerecoin
7 May 1949 17:09 30.90 116.40 4.1 Yerecoin
11 March 1952 06:09 31.30 116.50 5.1 Bolgart
27 November 1954 08:36 32.00 116.7 3.9 Talbot Brook
29 April 1955 09:14 30.90 116.40 4.7 Yerecoin
29 April 1955 19:49 30.90 116.40 4.4 Yerecoin
29 August 1955 06:09 30.70 116.40 5.3 Gabalong
30 August 1955 13:52 30.70 116.40 5.8 Gabalong
30 August 1955 14:07 30.70 116.40 4.7 Gabalong
30 August 1955 16:46 30.70 116.40 4.6 Gabalong
24 February 1956 06:27 30.9 116.4 4.5 Yerecoin
5 April 1956 23:13 30.9 116.4 4.5 Yerecoin
20 March 1958 03:03 32.20 117.20 4.8 Beverley, Brookton
3 October 1959 12:07:22.0[20] 34.50 114.50 4.2 55 km SW Cape Leeuwin
12 June 1961 18.00:51.0 34.20 114.50 4.1 50 km SW Cape Leeuwin

Notes

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  1. ^ First named by H.A.Doyle (1971) Seismicity and Structure in Australia Royal Society of New Zealand Bulletin Vol.9 pp. 149–152
  2. ^ a b Leonard, M; Darby, D; Hu, G (2007). GPS-geodetic monitoring of the South West Seismic Zone of Western Australia: progress after two observation epochs in 2002 and 2006 (PDF). Australian Earthquake Engineering Society 2007, Wollongong. Archived (PDF) from the original on 20 July 2008. Retrieved 2 June 2019. The Australian southwest seismic zone (SWSZ) is a north-south trending belt of intra-plate earthquake activity that occurs in the southwest of Western Australia, bounded by 30.5°S to 32.5°S and 115.5°E to 118°E. This is one of the most seismically active areas in Australia, with nine earthquakes over magnitude 5.0 occurring between 1968 and 2002; the largest of these was the M6.8 Meckering earthquake in 1968. Since the SWSZ lies as close as ~150 km from the ~1.4 million population of the Perth region, it poses a distinct seismic hazard.
  3. ^ Featherstone, W.E; Penna, N.T; Leonard, M; Clark, D; Dawson, J; Dentith, Mike; Darby, D; Mccarthy, R (2004), GPS-geodetic deformation monitoring of the south-west seismic zone of Western Australia : review, description of methodology and results from epoch-one, ISSN 0035-922X
  4. ^ Fairbairn, David (16 October 1968), W.A. earthquake equals Australia's biggest ever, retrieved 1 September 2023
  5. ^ Geological Survey of Western Australia (1975), The Geology of Western Australia, Western Australia Geological Survey, ISBN 978-0-7244-6084-7 – section Southwestern Province by I.R. Williams page 65
  6. ^ Dent, V. F. (Victor Francis); Australia. Bureau of Mineral Resources, Geology and Geophysics (1989), Computer generated crustal models for the south west seismic zone Western Australia, Bureau of Mineral Resources, Geology & Geophysics, retrieved 1 September 2023
  7. ^ Geological Survey of Western Australia (1975), The Geology of Western Australia, Western Australia Geological Survey, ISBN 978-0-7244-6084-7 – section Yilgarn Block by I.R. Williams pages 33–81 – now called Yilgarn Craton
  8. ^ a b "School of Earth Sciences | Science".
  9. ^ "Magnitude-5.7 earthquake rocks southern WA". Australian Broadcasting Corporation. 17 September 2018. Retrieved 9 November 2018.
  10. ^ "Magnitude-4.7 earthquake rocks area surrounding Lake Muir in WA's Great Southern". Australian Broadcasting Corporation. 13 October 2018. Retrieved 9 November 2018.
  11. ^ Ben Anderson (9 November 2018). "Earthquake at Lake Muir shakes Perth and WA's South West". News Corporation. Retrieved 9 November 2018.
  12. ^ "Recent Earthquakes Lake Muir area,WA". Geoscience Australia. Retrieved 12 November 2018.
  13. ^ "Earthquake 'swarm' rattles WA's south with more than 40 over three weeks". ABC News. 24 January 2022. Retrieved 25 January 2022.
  14. ^ http://www.abc.net.au/catalyst/stories/s392312.htm PerthQuake
  15. ^ M.O. Michael-Leiba Temporal variation in seismicity of the Southwest Seismic Zone, Western Australia: implications for earthquake risk assessment, Geoscience Australia
  16. ^ Geological Society of Australia. Specialist Group on Solid-Earth Geophysics (3 June 1996), "Crustal Structure In The Southwest Yilgarn Craton, Western Australia – An Explanation For The Southwest Seismic Zone? (3 June 1996)", Geophysics Down Under: Newsletter of the Specialist Group on Solid-Earth Geophysics (23), Geological Society of Australia. Specialist Group on Solid-Earth Geophysics: 4, ISSN 1035-0853
  17. ^ Dent, Victor; Harris, P; Hardy, D (2010), A new seismograph network in the southwest seismic zone of Western Australia, Australian Earthquake Engineering Society, ISBN 978-0-9807420-2-2
  18. ^ Reading, AM; Kennett, BLN; Dentith, MC (2003), "Seismic structure of the Yilgarn Craton, Western Australia", Australian Journal of Earth Sciences, 50 (3): 427, Bibcode:2003AuJES..50..427R, doi:10.1046/j.1440-0952.2003.01000.x, S2CID 10466512, retrieved 30 October 2021
  19. ^ Gordon, F.R and J.D. Lewis (1980) The Meckering and Calingiri earthquakes October 1968 and March 1970 Geological Survey of Western Australia Bulletin 126 ISBN 0-7244-8082-X – Appendix 1 – Catalogue of Larger earthquakes recorded in Southwestern Australia – Table 22. Earthquakes of Magnitude 4 or more -page 213
  20. ^ Following start of Mundaring Observatory more precise times were recorded.

See also

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References

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  • Featherstone, Will (1998) Geodetic monitoring of the South West Seismic Zone paper at Curtin University of Technology 24 25 September 1998 to the Advances in Deformation Monitoring International Workshop
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