Two small earthquakes have struck at a shallow depth close to populated areas of Auckland.
GNS Science says a 3.9 quake recorded at 4.05pm on Sunday at a depth of six kilometres was centred 15 kilometres north-east of the city.
A 3.1 quake recorded in the same spot four minutes earlier was only four kilometres deep.
Duty seismologist Caroline Holden says the Auckland region is active, with at least 60 or more volcanoes.
She says swarms of earthquakes do happen in the northern region, but nothing strong has been felt in Auckland for five years.
Police say they got more than 50 calls related to the quakes, but no reports of injuries or damage to buildings.
People have told Radio New Zealand they felt a strong jolt and their houses shook when the bigger quake hit, prompting some to flee outside.
Some wandered the streets wondering whether it was safe to return home.
Otahuhu resident Raewyn Paea says the shake lasted about one minute and caused everything to rattle in her home.
