A thundering roar heralded a magnitude 7 earthquake that shook Wairarapa awake on Tuesday night.
The earthquake struck at 10.36pm and was centred 60km southwest of Opunake at a depth of 230km, according to GNS Science.
It was the second tremor felt in Wairarapa on Tuesday, after a magnitude 3.6 earthquake struck 10km north of Masterton at a depth of 20km at 9.39am.
The large night-time jolt was felt in centres from the Bay of Plenty to Canterbury and a small aftershock of magnitude 3.8 struck 15km east of Christchurch just after 11pm on Tuesday.
Reports were widespread in Wairarapa of an ominous sound that preceded the quake, although there were few reports of damage in the region.
Bideford resident Shaun Minifie posted to the Wairarapa Times-Age Facebook page that "you could hear it above the TV, coming down the valley". He described the experience as "very surreal".
Toby Mills posted that "the noise came about 10 seconds before the shaking started. I thought it was a very large truck but it was too loud."
Carterton woman Catherine O'Driscoll said: "The noise in Carterton was that loud I thought one of the boy racers had hit a pole."
Janice Emerson posted that: "We heard it above the television but I could feel the motion beforehand then the horrible shake."
A Briscoes spokeswoman said yesterday a single glass had fallen from a shelf and broken in the Masterton store and "a couple" of items had been shaken from their racks on Tuesday night.
Pak'n Save Masterton manager Stuart de Lara-Bell said there had been no reports of disrupted or damaged stock at the Kuripuni supermarket in the wake of the earthquake.
Masterton district emergency management officer Paul Walker said he had fielded several phone calls on Tuesday night about the shake, including from his son in Nelson, but there were no reports of quake damage in Wairarapa. Mr Walker said that, in the event of an earthquake, Wairarapa residents caught indoors should drop and take cover under sturdy furniture or against an interior wall away from windows.
He said residents should have located safe places in their homes or places of work before an earthquake, to allow a quick escape to safety.
Mr Walker said there was to be a nationwide "drop, cover, hold" earthquake drill at 9.26am on September 26 that had been set down before the large quake struck on Tuesday night.
Registrations have opened for the ShakeOut drill, which aims to involve a million people throughout New Zealand. For more information go online to www.getthru.govt.nz.