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Seismicity of Western Australia

Introduction
Major West Australian Earthquakes
Seismicity of  Southwest WA

Seismicity of the WA Goldfields

Seismicity of the North of WA

Reference material (PDF format)


INTRODUCTION

Earthquakes are more common in Australia than many people realise. The majority of earthquakes located in Australia over the years would be in Western Australia, though this is due in part to the fact that it is Australia's largest state. Maps of the most recent earthquakes in WA are shown on a separate page.

In order to compute earthquake risk in Australia, using a technique known as the Cornell-McGuire method, Brian Gaull and Marion Leiba (1990) divided Australia into a number of earthquake source zones ( see map below). 13 of these source zones are in Western Australia. While ideas on seismicity have evolved since then, this map gives an idea of the major sources of seismicity in Western Australia and Australia in general. Notable is the low seismicity attributed to the Northern Territory. Earthquakes in this region since 1987 have dramatically changed the level of seismic risk attributed to this region of Australia.

The map below shows known earthquakes of magnitude 5.5 and above in Western Australia from 1885 to March 2004

MAJOR WA EQS

The most significant concentration of seismic activity is probably off the northwest coast of the state. The on-shore region of the northwest also has elevated seismicity. There is also an apparent concentration of earthquakes in the south west of the state, which is of particular interest to seismologists. The region is now generally known as the SouthWest Seismic Zone.

As yet there is no clear scientific reason why the northwest and southwest regions should possess higher than average levels of seismicity.

Important (Mag 4.1 or greater) WA earthquake since 2006

DATEMagLocationRemarks
6 Jun 20064.5Mt Clere
15 Feb 20075.3Shark Bay
28 Aug 20074.6Sth of Augusta
09 Oct 20074.8SW of KatanningSWSZ
07 Nov 20074.4NE of Carnarvon
28 May 20084.8Sth of Broome
09 July 20084.5West of Warburton
29 July 20084.5Scott Reef, off NW shelf
31 Jan 20094.6NW of Beacon ~ 300k NE of PerthSWSZ
31 Jan 20094.4NW of BeaconSWSZ
05 Mar 20094.5NW of BeaconSWSZ
06 Mar 20095.1NW of Broome
25 Jun 20094.2SW of BeaconSWSZ
05 Apr 20105.0~ 1500 k Sth of Esperance
20 Apr 20105.0Kalgoorlie
17 Apr 20115.3Nth of Exmouth, WA
07 May 20114.0NE of Broome
20 May 20114.5SW of Mt Newman, WA
14 July 20114.5NE of Marble Bar

vvvv

HISTORICAL MAJOR WEST AUSTRALIAN EARTHQUAKES


The three most significant earthquakes since the European settlement of WA in 1824 were at Meeberrie in 1941, Meckering in 1968, and at Cadoux in 1979. The Meeberrie earthquake (approximately 300 km northeast of Geraldton), at magnitude 7.1, was possibly the largest known Australian earthquake, but caused no reported damage because of its remote location. The Meckering earthquake (150 km east of Perth), at magnitude 6.9, caused the most damage of any known Australian earthquake, until the Newcastle NSW earthquake of December 1989. The Newcastle earthquake had a magnitude of 5.6, and resulted in the deaths of 13 people (11 in one building, the Newcastle Worker's Club). No other Australian earthquakes have caused fatalities.

The Meckering earthquake occurred at 0258 hrs GMT, and produced surface faulting over roughly 20 square km. The principal fault scarp was nearly 37 km long, aligned approx N-S, and had a maximum observed vertical displacement of 3.5 metres. It was felt over a radius of approx 1000 km, and caused minor alarm in Perth, approx 150 km to the west of the epicentre. On the basis of old breccia found in the fault zone in 1968, and trenching across the scarp in 1990, it has been concluded that the Meckering earthquake was the result of the reactivation of an old fault line, possibly tens of thousands years old.

HISTORICAL EARTHQUAKES OF WESTERN AUSTRALIA

 

Earthquakes, magnitude greater than or equal to 5.5, 1880 - 2000


UT Date Time Longit Latitude  eML Felt I

1885- 1- 5 1220  0.0 114.000 -29.000     6.6  6
1873-12-15 0400  0.0 127.500 -26.250     6.2  7
1906-11-19 0718 41.0 111.800 -19.100     7.5  5 
1929- 8-16 2128 23.4 120.660 -16.990     6.6  4 BROOME
1941- 4-29 1354 41.0 116.100 -26.800     7.3  8 MEEBERRIE
1946- 4-19 2113 00.0 114.500 -33.500     5.7   
1955- 8-30 1352 00.0 116.400 -30.700     5.8 GABALONG
1959-11-27 0625 22.0 116.200 -25.800     5.9
 
1961- 8-23 1801 33.0 119.000 -18.500     5.8
1961-11-10 1459 14.0 118.400 -37.500     5.6
1962- 1- 1 2329 52.0 125.700 -34.100     5.6
1963- 8-27 1915 43.0 128.600 -16.600     5.6
1964- 3-23 2241 16.1 123.160 -17.710     6.3 DERBY
1965- 5-19 0213 47.0 112.040 -24.980     5.9 CARNARVON
1966- 2-23 0340 13.0 106.800 -37.800     5.8
1966- 4-30 0325 00.0 120.500 -16.400     5.5
1966-11-13 0341 43.7 111.670 -23.970     5.9
1967- 4- 4 0558 02.0 114.000 -38.200     5.6
1967-11-28 0830 14.0 113.500 -19.000     5.5
1968- 6-19 0555 34.3 125.030 -19.090     5.5 FITZROY CROSSING
1968- 6-30 1921 16.9 121.440 -16.310     5.5
1968- 8- 6 1908 52.0 123.200 -18.500     5.8
1968-10-14 0258 50.6 116.980 -31.620     6.9  9   MECKERING
1968-10-15 0330  7.0 117.030 -31.680     5.7 
1969- 6-17 1954 32.7 116.730 -25.260     5.6  5   LANDOR
1969- 9-24 2339  0.5 117.750 -21.330     5.5 
1970- 2- 1 1840 56.1 118.500 -20.300     5.5  
1970- 2- 8 1631 25.7 125.380 -27.890     5.5 
1970- 3-10 1715 11.2 116.470 -31.110     5.9  6  Calingiri
1970- 3-24 1035 17.6 126.610 -22.050     6.7  5  Lake Tobin
1970- 3-25 0031 51.4 126.560 -22.000     5.5      Lake Tobin
1970- 3-25 0508 54.8 126.590 -22.230     6.4  Lake Tobin
1970- 4- 4 1409 40.6 126.460 -21.870     5.6  Lake Tobin
1971- 3-11 0323  8.5 126.550 -22.070     5.8  Lake Tobin
1971- 7-12 2259 38.1 115.160 -24.540     5.5 
1971- 7-16 0800  1.0 126.560 -22.030     6.4  Lake Tobin
1972- 2-16 1211  5.4 126.580 -22.070     5.8      Lake Tobin
1973- 6-18 1934 13.0 110.200 -33.500     5.9 
1974-11- 7 0153 31.5 118.650 -18.160     5.8 
1974-11-17 1453 44.4 126.530 -22.000     5.5  Lake Tobin
1975- 1-10 0820 18.3 126.110 -27.740     6.2 
1975- 3- 6 2351 26.3 126.380 -17.080     5.6  5 
1975-10- 3 1151  1.8 126.580 -22.210     6.2  Lake Tobin
1976- 2-19 0232  5.3 114.300 -19.410     6.2  Nth of Exmouth
1976- 3-15 1538 35.9 125.470 -32.340     5.6  Cocklebiddy
1978- 5- 1 0342 47.2 115.590 -23.640     5.7  4   Maroondah Homestead
1978- 5- 6 1952 19.6 126.560 -19.550     6.8  4  Nth of Lake Tobin
1979- 6- 2 0948  1.0 117.150 -30.830     6.2  9   CADOUX
1979- 6- 7 0645 16.1 117.160 -30.810     5.5      Cadoux
1979- 7-14 0940 56.6 122.820 -18.420     5.8  Broome
1985- 5- 5 1650 23.7 116.855 -25.947     5.6 P 
1985- 7-28 0739 47.3 122.220 -32.510     5.6 Norseman
1988- 2- 6 0523 58.0 124.510 -16.180     5.7 Derby

1990- 1-17 0638  8.2 116.990 -31.720     5.8  6  Meckering
1997-08-10 0920 31.0 124.329 -16.013 6.3 Cockatoo Island


WEST AUSTRALIAN EARTHQUAKES BY REGION

SEISMICITY OF SOUTH WEST WESTERN AUSTRALIA

The seismicity of south west Western Australia is of particular interest, partly because includes the region around the state's principal city, Perth, and also because it contains a zone of higher than normal seismicity, known as the SouthWest Seismic Zone. This region frequently sees intense bursts of seismic activity, known as clusters or "swarms". Recent important clusters include those near Kellerberrin (1996-97), near Burakin (2001-03), near Kalannie (2004-05) and near Beacon (2009). 

For more information on recent seismicity in the SWSZ, refer to "Reference Material"

The map below shown all known earthquakes in the region of magnitude 5.0 or more.

LIST OF MAJOR EARTHQUAKES IN SW WESTERN AUSTRALIA

1946April 19Yallingup5.7
1949May 2Yerecoin5.1
1952Mar 11Bolgart5.1
1955Aug 29Gabalong5.3
1955Aug 30Gabalong5.8
1959Oct 03SW of Augusta5.0
1961Nov 10S of Albany5.1
1963Jan 18Beverley5.4
1966Feb 23S of Beverley5.0
1968Oct 14Meckering6.9
1968Oct 15Meckering5.7
1970Mar 10Calingiri5.9
1979June 02Cadoux6.2
1979June 03Cadoux5.3
1979June 07Cadoux5.5
1979Oct 11Cadoux5.0
1980Dec 09W of Fremantle5.2
1980Dec 10Cadoux5.0
1990Jan 17Meckering5.5
2001Sep 28Burakin5.2
2002Mar 05Burakin5.0
2002Mar 30Burakin5.2
2007Oct 09S of Katanning4.8

The map below shows earthquakes in the southwest, of magnitude 3.0 and above, Jan 1990 to Aug 2005

Yellow - Magnitude 5.0 - 5.9

Orange - Magnitude 4.0 - 4.9

Pink - Magnitude 3.0 - 3.9

Earthquakes in the southwest, magnitude 4.5 & above, since 1990

DATELATITUDELONGITUDEMAGLOCATION
17 Jan 1990-31.72116.995.5Meckering
08 May 1990-30.779117.1024.5Cadoux
31 Aug 1997-31.449117.6844.6Kellerberrin
28 Sep 2001-30.536117.0615.2Burakin
28 Dec 2001-30.533117.0684.5Burakin
05 Mar 2002-30.479117.0845.0Burakin
05 Mar 2002-30.521117.0654.8Burakin
30 Mar 2002-30.524117.0495.2Burakin
12 Jun 2005-30.558117.034.5Burakin
09 Oct 2007-33.946117.5054.8Katanning
31 Jan 2009-30.230117.7844.6Beacon


Background to "The South West Seismic Zone"

The Australian Federal Government established a geophysical observatory at Mundaring, on the eastern outskirts of Perth, in 1957. In the 1960's, a seismologist at the Observatory, Ian Everingham, identified a region, roughly between Geraldton and Albany, that was apparently more prone to earthquakes than most other regions of WA. He named this zone the "Yandanooka - Cape Riche Lineament". This was later referred to by geologist Ray Gordon as "The South West Seismic Zone", a name which is now established in the literature.

Since the 1960's, the zone has become more extensive, and less well defined than originally proposed. However, earthquakes which have occurred since then have confirmed Everingham's observation that this is a region of higher than average seismicity. In particular, two major earthquakes have occurred in the northern part of this zone - at Meckering, in October 1968 (magnitude 6.9), and at Cadoux, in June 1979 (magnitude 6.1). Both of these earthquakes caused major damage, running into millions of dollars.

BELOW - the Yandanooka - Cape Riche lineament as originally defined by Ian Everingham.

The exact boundaries of the Southwest seismic zone are still imprecise, and the reasons why this zone should exist at all are also not understood. The zone exists within an Archaean Shield structure called the Yilgarn Block. The identified geological subdivisions within this Precambrian structure do not show an obvious relation to the seismicity.

Fortunately, Perth is outside of the earthquake zone. No earthquake of magnitude greater than 2 is known to have occurred in the Perth metropolitan region. Large blasts associated with engineering or farming activity can sometimes be confused with natural seismic activity. The closest confirmed seismic activity to Perth has been at Wooroloo, approximately 50 km east of Perth, where several earthquakes of magnitude just over 2 have been recorded. Several earthquakes of magnitude approximately 4 have been recorded close to York, approximately 100 km east of Perth. York is thought to be on the western margin of the SWSZ.

The Meckering and Cadoux earthquakes both caused ruptures at the Earth's surface - a rather rare occurrence. Only about 12 earthquakes in Australia's modern history have caused surface rupturing. These include a major earthquake near Tennant Creek (NT) in 1988, an earthquake at Marryat Creek in northern SA in 1986 and an earthquake near Calingiri ( in the SWSZ) in 1970.

BELOW - map of earthquakes in the SW of WA

1997 - 2000 -Blue ; 2001 - March 2004 -Red


An interesting aspect of the seismicity of Western Australia is the lack of topographic relief in the seismogenic areas, as the accompanying plot on a DEM ( courtesy of Geoscience Australia) shows. Note the fact that the Darling Scarp is well defined, but not associated with seismicity.

BELOW - Locality map for central Wheat-belt area of WA

SEISMICITY IN THE EASTERN GOLDFIELDS REGION

One of the most significant events in this region occurred on 20th April, 2010, about 15 km south of Kalgoorlie, and very close to the historic town of Boulder. Significant building damage was done in this area. The earthquake had a magnitude of 5.0, and occurred just after 8 am. The nearby "Superpit" gold mine was closed for operations for about a week after the earthquake. A report on the earthquake was delivered by Johnathon Bathgate at the AEES conference in Perth, WA in Nov 2010.

It has been suggested that earthquakes in this region may fall in a poorly defined zone which trends towards the northeast, and may reach the WA - SA border. The most significant earthquake in the region was the magnitude 5.6 event near Norseman in 1985. 10 aftershocks of magnitude > 4, and nearly 60 of magnitude 3 - 3.9 were recorded from this event to 1999, and more may well be recorded.

The largest event close to Kalgoorlie was a magnitude 4.5 event in October 1987. It was located at 11 km northeast of Coolgardie, but this location could be +/- 20 km.

A magnitude 3.7 event occurred approximately 30 km SE of Kambalda on the morning of 31 May, 2004, and was felt widely in the region. Although it was close to an active mine, it is not believed to be mining induced seismicity.

Below - map of earthquakes, Mag 4.5 or greater, Jan 1970 - Sept 2004 (28 - 36 Deg S, 120 - 126 Deg E)

Details of the major events

DATE

LAT

LONG

MAG

COMMENTS

15 Mar 76-32.34125.475.2near coast, E of Balladonia
28 Jul 85-32.51122.225.6Norseman area, 3 aftershocks of Mag > 4.4
09 Oct 87-30.913121.2624.5close to Kalgoorlie
03 Mar 89-29.6123.655.41 foreshock of Mag > 4.4
19 Oct 01-33.608120.5935.2near Ravensthorpe, felt widely
20 Apr 2010-30.787121.4895.0significant building damage at Boulder


SEISMICITY OF NORTHERN WESTERN AUSTRALIA

Relative to the rest of the Australian continent, northern Western Australia is quite seismically active. Much of this seismicity occurs offshore, but large earthquakes have also been recorded onshore.

One of the largest earthquakes known in the Austalian region occurred off the northwest coast on 19 Nov 1906. It was given a magnitude of 7.75 by Gutenburg & Richter (1954) and the location of Stover (1966) puts it at 19.1 south, 111.8 east. It was felt over the entire western half of Western Australia.

In recent times, a magnitude 6.3 event occurred at Collier Bay, approx 200 Km NE of Broome in Aug 1997, and a magnitude 6.6 earthquake occurred about 200 km west of Broome on 22 April 1979. A magnitude 5.1 event occurred northwest of Exmouth in October 2000.

The map below shows all known earthquakes in the region, of magnitude 5.0 or more. Earthquakes of magnitude 6.0 or greater are shown in yellow

EARTHQUAKES OF MAGNITUDE 6.0 OR GREATER

DATE

LATITUDE

LONGITUDE

MAG

REMARKS

1906-19.1111.87.7unreliable location - not plotted above
1929-17120.666.6felt in Broome
1934-15112.56approx 500k N of Exmouth - unreliable
1968-19.1125.036Canning Basin
1970-22.05126.616.7Lake Mackay
1978-19.55126.566.2Canning Basin
1979-16.66120.276.6off Broome
1997-16.05124.426.3Cockatoo Is

Important earthquakes in the north of WA were felt events at Broome in 1929, Derby in 1964, Broome in 1979 and again at Derby in 1988. A number of large events occurred near Lake MacKay in 1970, and aftershocks occurred for many years. The most recent large event was near Cockatoo Island, in Yampi Sound, in 1997 ( magnitude 6.3).

The first seismic station in the north of WA was installed at Kununurra in 1965. The accuracy of earthquake locations in the north of WA was improved greatly by the installation of stations at Marble bar in 1976 and at Nanutarra in 1980.

SEISMIC STATIONS IN THE NORTHWEST

LOCATION

CODE

LAT

LONG

Status

Predecessors

NanutarraNANU-22.562115.529closed 1995 Feb 28NAU opened 1980 Apr 19
GiraliaGIRL-22.570115.521opened Dec 95replaced Nanutarra stns
Fitzroy CrossingFITZ-18.102125.639opened 1996 Sep 11FITX opened 1995 Mar 19
Marble BarMBWA-21.159119.731opened 2001 Aug 25MBL opened 1976 Jun 23
KununurraKNA-15.75128.767opened Nov 1965

Reference material

#Recent papers# presented at conferences of the Australian Earthquake Engineering Society, relevant to the southwest seismic zone of Western Australia

Earthquake swarms in Australia - by Vic Dent AEES, 2008 (Ballarat)

Discussion of the Mag 4.9 Katanning earthquake of 2008  by V. Dent

Discussion of the 2009 Beacon WA earthquake swarm by V. Dent

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