A small earthquake has hit the Adelaide Hills.
The tremor registered a magnitude of about 4 and hit in the area in the city's north-east at about 11.30pm (CST) on Friday, but was felt as far as 50km away from its epicentre, Geoscience Australia seismologist David Jepsen told AAP.
No one was injured and the tremor is not believed to have caused any significant damage, he said.
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However emergency services received a lot of phone calls from anxious people all over Adelaide and nearby towns that had felt the tremor.
"The event would have lasted 2-3 seconds and would have been felt as strong shaking, the severity depending on what they were doing at the time," he said.
"This is the earth doing its normal stuff ... when the stress of the plates exceeds the strength of the rocks underneath it releases energy."
Friday night's tremor was strong by Adelaide's standards, but a previous earthquake in 1954 was 5.4 magnitude, occurred near the heart of the city and caused the equivalent of $6 million damage to property, Mr Jepsen said.
Earthquakes between three and four magnitude are often felt, with shaking occurring, but rarely cause serious damage.
