Geoscience Australia recorded a Magnitude 3.4 Earthquake at a depth of 2 km, roughly 45 km northeast of Newcastle in New South Wales, slightly after 9.20 am local time on Friday 9 August 2013 (slightly after 11.20 pm on Thursday 8 August, GMT). There are no reports of any damage or casualties from this quake, though it was felt as far away as Muswellbrook.
The approximate location of the 9 August 2013 New South Wales Earthquake. Google Maps.
While New South Wales doe suffer occasional Earthquakes, these tend to be small and infrequent, making their precise causes hard to determine. The state is far from any tectonic plate margin that might provide an obvious cause. Many ancient sedimentary beds in southeast Australia are stacked at fairly steep angles, the result of fold mountain formation during the assembly of the supercontinent of Pangea (though the mountains themselves have largely eroded away), which can make the area slightly more quake-prone than would otherwise be expected.
Witness statements can help geologists to understand Earthquakes and the geological processes that cause them; if you felt this quake you can report it to Geoscience Australia here.
See also Earthquake off the coast of New South Wales, Minor Earthquake in New South Wales, Earthquake in New South Wales, Melbourne shaken by Earthquake and Canberra shaken by mild Earthquake
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