More aftershocks have been felt in Christchurch on Thursday, but there are no reports of significant damage.
The first and most severe quake was magnitude 5.1 at a depth of 10km. It occurred at 6.03am and was felt as far afield as Dunedin and Greymouth.
There have been eight other quakes with many shallow and near the city centre since then measuring between magnitude 4.0 and 3.2.
Medical professionals say nearly everyone visiting the doctor on Thursday is reporting some sort of quake-related ailment.
GNS Science says such aftershocks are to be expected and residents should prepare for shakes of this intensity every four to six weeks for up to a year.
There have been 4500 aftershocks since the main 7.1-magnitude quake on 4 September. The epicentre of that quake was 40km west of Christchurch at a depth of 10km.
