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
List of earthquakes of magnitude 4 or more in Southwestern Australia 1920–1961(based in part on the records of Perth Observatory 1923–1959 andMundaring 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
See also
References
- 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