A 3.3 magnitude earthquake struck Adelaide CBD, waking up residents at 2:22am Wednesday.

The shallow quake was felt across the city for about five seconds, with the epicentre believed to be in the south eastern suburb of Upper Sturt, according to ABC news.

David Jepson from Geoscience Australia told 891 Breakfast the quake happened at approximately 10 kilometres southeast of the CBD, 17 kilometres below the surface.

"South Australia has lots of earthquakes and most of those earthquakes are in the northern part of the state, up through the Flinders Ranges... We do get the odd earthquake around Adelaide," said Jepson, adding the Australian plate was being compressed and as this compression stress was being released, random earthquakes would be felt in Adelaide.

Jepson said he expected the area to experience a number of smaller size quakes and not a disastrous one.