Christchurch was rattled by a magnitude 4.0 earthquake this morning.
GNS Science said the 12km deep quake struck 10km southwest of the city at 11.07am.
Twitter users described the quake as noisy, with one describing it as a "big booming wobble".
Another tweeted they thought it was the start of last February's quake "all over again".
A police southern communications spokesman said there had been no reports of damage.
The quake was followed almost an hour later by a magnitude 3.0 shake.
The 7km deep quake struck 10km southwest of Christchurch at 12.06pm.
