Reports of the shake started at 1.22pm (ACDT) in the town of Hawker in the Flinders Ranges.
The epicentre appears to be near Flinders Ranges National Park, according to Geoscience Australia.
The quake struck 13 kilometres deep and was felt by more than 120 people.
The earthquake was initially measured at a 5.1 magnitude.
Residents in surrounding suburbs reported feeling the quake on social media.
“We felt this,” sheep and cattle station Mern Merna Station posted on Facebook.
