Earthquakes in the Canberra Region - Geoscience Australia

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Earthquakes in the Canberra RegionA magnitude MD 2.1 earthquake, with an epicentre 3 km west of the northwest corner ofFigure 2, and 33 km NNW of the Canberra GPO, was felt at Hall and Flynn in the ACT at9.27 am E.A.S.T. on 9 August 1987.In 1993, two small earthquakes were felt at Murrumbateman. Their epicentres were 31and 32 km NNW of the Canberra GPO and they happened at 5.16 pm on 29 May and 7.34pm E.A.S.T. on 1 June. They are probably related. Their magnitudes were ML 1.2 and1.6 respectively. The first of these earthquakes was felt inside and in the open byresidents near the epicentre. It made windows and saucepan lids rattle and sounded asthough something had hit the house or landed on the roof. The second was felt byresidents of the township and sounded like a loud explosion.Table 3. Earthquakes within a square with sides 10 km from Murrumbateman,January 1996 – November 2007DATE TIME- LAT LON DEPTH MAG COMMENTS(UTC)19970215 211915.2 -34.968 149.103 3.0 1.2 27km S DaltonNSW20000425 32405.1 -35.052 149.007 8.0 2.5 MurrumbatemanNSW. Felt20000723 3624.4 -34.97 148.97 0.0 1.5 MurrumbatemanNSW20010109 214554.7 -35.059 149.01 3.0 2.5 Murrumbatemanarea NSW.Felt20010324 120701.9 -34.984 149.085 2.0 1.8 MurrumbatemanNSW20010324 133856.7 -34.99 149.04 7.0 2.8 MurrumbatemanNSW. Felt20030114 134315.3 -35.019 149.012 1.3 3.1 MurrumbatemanNSW. FeltEarthquakes in the vicinity of Murrumbateman during the period January 1996 –November 2007 are listed in Table 3. A total of seven events occurred during this period,six of which were main shocks. This gives an average of 0.5 main shocks per year, similarto the period 1981-1995, suggesting that the average level of earthquake activity hasremained almost the same. Three of these events were in the area of Figure 2.Four of the earthquakes in Table 3 were felt.The magnitude 2.5 event at 1.24 pm local time on 25 April 2000 was felt by all residentsof a Murrumbateman property, 1 km from the Boral quarry, and all thought it was anexplosion. Our informant noted that things in the kitchen sink lifted then fell, but nothingfell off the shelves.The same person also reported that she and her neighbours felt the magnitude 2.5earthquake of 10 January 2001 at 8.45 am local time. This sounded and felt like anexplosion, and she felt the “air” pick up and drop the house on one corner. Her pet catsstood with their hair on end. Her property was at the epicentre of the earthquake, but itwas also reported felt by one person in Spence, ACT. He was sitting at a desk when hefelt/heard a rumble then a shake with the vibration of the floor.21
Earthquakes in the Canberra RegionOne person in Murrumbateman reported feeling the magnitude 2.8 event at 12.38 am localtime on 25 March 2001, but no details are available. It seems that most people wereasleep then.By contrast, the magnitude 3.1 earthquake of 15 January 2003 at 12.43 am local time wasfelt by many people in the Murrumbateman area, and woke a number of them. It wasexperienced as an explosion which shook several houses. One person, who was wokenup, felt as though a car ran into his house, while another reported that a tap handle fell off.A seismologically-minded resident described hearing a “loud explosive bang as p wavecame straight up, like many events at Dalton Gunning. Heard s wave faintly rumblingaway to the south”. The explosion-like bang woke them, and her husband went outside tolook around.The largest known earthquake within 10 km of Murrumbateman had an intensity-basedRichter magnitude of 4.0. It happened on 7 March 1924 at 9.45 am local time and itsepicentre was 8 km northwest of the township. According to Cotton (1925), "At the townof Murrumbateman the shock was exceptionally severe; articles were thrown down fromshelves, and the plaster fell in several houses, being thrown right across the room from thenorth west wall to the south east in one case. The ground was observed to heave andwave, and fences and trees rocked perceptibly. A 1000-gallon water tank swayed in analarming manner." Its isoseismal map (Everingham and others, 1982) indicates that theearthquake was felt in the northwesternmost part of the ACT.DALTON-GUNNING EARTHQUAKES AND THEIR EFFECT ON CANBERRAThe Dalton-Gunning Zone, only 60 km north of Canberra, has been assessed as one of thehighest hazard earthquake areas in eastern Australia (Gaull and others, 1990). Threeearthquakes with Richter magnitudes of 5.5 or greater are known to have occurred, duringthe last 130 years, in November 1886, November 1934 and March 1949 (McCue andothers, 1989). All three were felt strongly in the Canberra area.The 1886 event caused damage in Yass and was felt in Queanbeyan with a ModifiedMercalli (MM) intensity of IV-V. The magnitude of 5.5 was deduced from the radius overwhich the shock was felt as there were no seismographs to record it (Everingham andothers, 1982).In the 1934 earthquake, practically every brick and stone building in Gunning wasdamaged and the event was felt over much of SE New South Wales. In Canberra, treesvibrated violently, a road appeared to be undulating, and the water in the swimming poolat Manuka was shaken, as was the telephone in the pool office. It wobbled so much that itbegan ringing. The magnitude of the earthquake was ML 5.6 (McCue and others, 1989),the same as that of the December 1989 Newcastle event.The magnitude ML 5.5 1949 earthquake was felt from Sydney and Katoomba in the northto Jindabyne, Cooma and Narooma in the south (Everingham and others, 1982).According to The Sun newspaper (Sydney) of 11 March 1949, the worst damage was inthe Dalton area where ``buildings swayed crazily, walls cracked, chimneys toppled, water22
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Earthquakes in the Canberra Region - Geoscience Australia

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