WELLINGTON - Wellington City Council's emergency management office has been activated on Sunday and its staff were trying to get a comprehensive picture of what damage has occurred following an earthquake on Sunday afternoon.

A 6.5 magnitude earthquake shook New Zealand capital Wellington and upper South Island on Sunday afternoon, following an earlier 5.8 quake on Sunday morning and a swarm of smaller quakes throughout the day.

Acting Emergency Controller Neville Brown said there has been some damage to the council offices, Radio New Zealand reported, adding that the council's call centre staff were being moved to new premises and the centre is expected to be operating again shortly.

Brown said there has been some damage to a council building in Wakefield Street as well as a city wharf.

He said there have been many isolated incidents across the region, water sprinklers broken, and power is out in some areas, but the roads appear to be undamaged.

Wellington Mayor Celia Wade-Brown is urging people to prepare an emergency kit in case there are any more quakes.

Celia Wade-Brown said there have been no reports of injuries or major damage so far, but she is asking people to be prepared by stocking up on water and food supplies.

The New Zealand National Crisis Management Centre said there is no threat of a tsunami from Sunday's earthquake.

The centre says the quake was magnitude 6.9, but that is provisional at this stage.

The Pacific Tsunami Warning Centre has issued a tsunami information bulletin saying there is no threat to New Zealand.

The National Crisis Management Centre has not been activated.