A magnitude 4.3 earthquake has struck near Christchurch.
Geonet said the "strong" intensity quake hit 15km east of the city at 1:35pm.
The quake is the largest to strike Christchurch since a magnitude 4.4 shock on July 16.
GNS Science duty seismologist Martin Reyners said it was a delayed aftershock from a 5.9 magnitude quake that struck on December 23 last year.
"It was quite a shock. It would have been a sharp reminder."
The quake was unlikely to cause anything more than minor damage, Mr Reyners said.
Many Christchurch residents reported feeling the quake strongly.
Desere Girdlestone said: "Thought King Kong was shaking my car."
Sel Leigh said: "Nothing like a fresh [earthquake] to send the oldies at work into a panic. Moving cars, jackets on, car keys at ready for "the next one in an hour"
The quake was followed by a 3.8 magnitude aftershock at 1:55pm.
It struck 20km east of Christchurch at a depth of 10km.
- nzherald.co.nzBy Hayden Donnell Email Hayden