Patches of slip on the Hikurangi subduction plate boundary beneath the North Island. GPS station movements are denoted by the arrows.

Slow-slip earthquakes have been detected in Kapiti and Manawatu, adding to similar activity already seen in Gisborne and Hawke's Bay.

The announcement by GeoNet of the slow slipping in the west of the lower North Island was followed about 9.30pm on Sunday by a widely felt magnitude-4.5 quake 35km west of Paraparaumu at a depth of 27km.

GNS Science duty seismologist Caroline Holden said that quake could be linked to the Kapiti slow-slip event, but could also be an aftershock of the magnitude-7.8 Kaikoura quake, which happened just after midnight on November 14.

GEONET The location west of Paraparaumu of Sunday night's magnitude-4.5 quake.

It was clearer that a cluster of earthquakes near Porangahau in Hawke's Bay was related to the slow-slip event in that part of the country, given they were further from the area of aftershocks related to the Kaikoura quake, Holden said.

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It is the first time slow-slip movements have been detected in multiple regions since the phenomenon was discovered in 2002.

Researchers were investigating the possibility passing seismic waves from the Kaikoura quake triggered the slow slipping.

The discovery of slow slipping on the west of the lower North Island comes as signs emerge that activity in Gisborne and Hawke's Bay may be tapering off, GeoNet said.

Slow-slip events in this country happen where the Pacific Plate meets the Australian Plate.

They take place over weeks or months without any shaking detectable by people or seismographs. Instead they are detected by a network of GPS stations around the country run by GeoNet and Land Information NZ.

By Saturday evening there had been about 15cm of slip across the Hikurangi subduction zone plate boundary in the Gisborne-Hawke's Bay event, equivalent to a magnitude-7.2 earthquake.

The Kapiti-Manawatu slow-slip involved movement across the boundary of 5-7cm in the past two weeks, equivalent to a magnitude-6.8 earthquake.

Also by Saturday, 225 earthquakes had been recorded in the Porangahau area since the Kaikoura quake. Most were smaller than magnitude 3 but did include a magnitude 5.5 quake 65km southeast of Porangahau on November 22.

Multiple slow-slip events could be typical following an event as big as the Kaikoura quake, GeoNet said. It was the first time slow slipping had been monitored after such a large quake in central New Zealand.