Christchurch was rattled by a magnitude 4.0 earthquake this morning.
GNS Science said the 12-kilometre-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.
