Aucklanders have reported feeling a magnitude 5.5 earthquake that struck the central North Island today.

More than 4000 people in 30 minutes reported feeling the earthquake which struck at 12.42pm and was centred about 10km north-east of Taupo, Geonet said.

The intensity was "moderate" but it drove thousands of people to the Geonet site.

Geonet FELT IT: Geonet's 'felt it' map at 1.15pm.

The tremor occurred at a depth of 110 km and was felt as far south as Akaroa and as far North as Auckland.

Most of the people reporting the quake on the Geonet site were in the central and lower North Island.

Geonet upgraded the magnitude to 5.5 from an earlier reading of 5.1.

Tony Bardsley said he felt a sharp jolt: "Am in Piopio Waikato, just had a moderate jolt 4-5 minutes ago. One jolt & things rattled but not off shelves."

Germain Hogue said it was a good one: "[I] am in Upper Hutt, Felt a low rumbling, the around 15 seconds after, louder rumbling and building shook a bit. Am working at Rimutaka Prison, in a solid concrete high security building, so normally don't feel too many quakes."

Ambulance central communications had not responded to any quake-related incidents, a spokeswoman said.

Constable Nick Weight, from Taupo police, said he felt a "bit of rumble, but nothing too intense". He was yet to receive calls from the public, he said.

Taupo Civil Defence manager Phil Parker was out of town but had spoken to colleagues at Taupo Council," where a lot of people dived under their desks".

He was trying to establish whether the quake had caused any damage but said he wasn't aware of any reports.

Today's tremor was the second large deep quake this week in the central North Island, following a 5.2-magnitude quake on Monday that was centred 15km southeast of Tokoroa at a depth of 195km.

GNS Science duty seismologist John Ristau said such large deep earthquakes were not uncommon. They were often felt a fair distance from where they happened.

"It takes the seismic energy some time and distance to travel through the earth and get to the surface," he said.

The mechanism of such quakes was not that well understood, because at the depth involved it was hard to see exactly what was going on. Often it could be a result of rocks fracturing as they heated water evaporated.

Ultimately all earthquakes in New Zealand had something to do with the country's location on the boundary between the Australian and Pacific plates.