Aftershocks are expected from an earthquake that shook residents awake along a stretch of Australia’s east coast.
The quake struck at 2.55am on Wednesday near Singleton in the New South Wales Hunter Valley, about 200km north of Sydney, Geoscience Australia seismologists said.
Its magnitude was initially read at 5.1 and later revised to 4.6.
No injuries were reported as a result of the tremor.
The quake’s epicentre was about 36km from Liddell, where the Coalition has proposed to build a nuclear power plant.
The NSW State Emergency Service received several phone calls from concerned residents but reported responding to only one incident. That was at a Rutherford property near Maitland that required sandbags for a burst water pipe shortly after 3am.
The tremor was felt between Port Macquarie and Wollongong, Geoscience Australia senior seismologist Phil Cummins said.
Sydneysiders were among more than 3,500 people who reported feeling the earthquake by 7.45am, according to Geoscience Australia’s website. Sydney residents also took to social media to report the quake had woken them up.
“It’s been widely felt … some of [the reports] were moderate and strong shaking,” Prof Cummins said.
Newcastle resident Simone, who asked for her surname to be withheld, told Guardian Australia she was woken by the sound of her glass shower doors rattling and at first thought it had been caused by wind.
Hunter MP Dan Repacholi was woken by the tremor and said his team was on the ground to help with any damage.
“Well that was a bit of a rude awakening ... [I] reckon most of the Hunter would’ve felt that shake,” he wrote on Facebook.
One Newcastle resident said the shaking frightened her to the point she thought someone was trying to break into her house.
“My bed lifted off the floor and the wardrobe doors were rattling ... at least I didn’t imagine it,” she wrote on Facebook.
Many “felt reports” in Sydney reported by individuals to Geoscience Australia appeared to have come from suburbs in which high-rise buildings are common, including Wentworth Point and Mascot.
Dr Ehsan Noroozinejad Farsangi, a senior researcher at the Urban Transformations Research Centre at Western Sydney University and the chief editor of the International Journal of Earthquake and Impact Engineering, said high-rise buildings were designed to sway during a quake.
“If you’re on the 30th floor, you’ll usually feel an earthquake more than someone in a bungalow, because tall buildings are designed like giant springs that sway and naturally amplify ground motions the higher you go,” he said.
“That extra wobble is a feature, not a flaw: the structure is flexing to dissipate energy, so it’s no more likely to collapse than a shorter, stiffer building. The real problem is psychological; our brains equate movement with danger.”
Preliminary information indicated the quake occurred at a shallow depth of 10km.
The Joint Australian Tsunami Warning Centre said the quake posed no tsunami threat to the Australian mainland, islands or territories.
Cummins said aftershocks were expected.
“They’ll probably be smaller, but some of them may be felt, and that may continue for a few days or even a week or more.”
The quake comes after a cluster of earthquakes in the region last year. Geoscience Australia recorded more than 40 earthquakes south of Muswellbrook in the Hunter Valley between 23 August and 31 October.
