Canterbury has been hit by two strong quakes within hours.
The 5.2 earthquake caused strong shaking near Cheviot just after 8am.
It hit 20km southwest of Cheviot at a depth of 12km and has been described as causing strong, swaying.
"Had a real swaying feeling & went for a while," one person said on Facebook.
Within minutes more than 1300 people had reported feeling it across the upper South Island.
GeoNet said the severe quake was part of the 7.8 Kaikoura aftershock sequence.
The region has escaped major damage from either quake and the Fire Service said it had no callouts as a result of today's tremors.
Cheviot woman Jane Thompson said the latest frightening quake had her heading for cover.
"As soon as it started I leaped under my desk and my dogs joined me," she said.
The latest tremor followed a strong, shallow quake that struck Canterbury before dawn, jolting people awake across the South Island.
GeoNet says the first quake, magnitude 4.7, struck at 5.17am.
It was centred 20km southwest of Cheviot and just 9km deep.
Nearly 500 people from Christchurch to the Manawatu reported feeling the tremor, and most were woken from their sleep.
Many described it starting with a loud crack followed by a bed-shaking wobble.
Those closest to the quake's epicentre have posted on social media about the jolt.
I JUST GOT WOKEN UP BY ANOTHER EARTHQUAKE— deena (@QueenAliKingx) March 1, 2017
Some are describing it as yet another setback after last year's Kaikoura 7.8 quake.
Waiau resident Jenny Holt posted on the GeoNet Facebook page: "My three kiddies terrified and crying in my bed now."
Jenna Wood wrote: "Heart racing. Stupid quakes bugger off! Felt in Woodend."
"Car shaking in Hornby felt as If was rolling," wrote Haydz Cranefield.