‘Quite uncommon’ – expert on the 50-year gap since the magnitude 5.1 earthquake like today shook Waikato and Auckland

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CCTV footage shows the moment a 5.1-magnitude earthquake hit Waikato just after 5.30am. video / provider

It’s been 50 years since a 5.1-magnitude earthquake struck a fault line near Te Aroha, Waikato, shaking thousands of people this morning – including as far away as Auckland.

GNS seismologist Dr Jane Andrews described the 5.1-magnitude earthquake that struck 5km south of Te Aroha, at a depth of 7km, at 5.30am as “quite uncommon”.

Reports of tremors flooded the internet early this morning from Kiwi as far afield as Tauranga, Hamilton, Cambridge and Boukeko.

A subsequent 3.9 earthquake struck Waikato and the Bay of Plenty at 11.29 am today as a follow-up to the 5.1 Te Aroha earthquake.

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“It’s not an area where we get a lot of earthquakes but it’s part of the Hauraki Rift,” Andrews said.

“It’s near the Kerepehi fault, so it’s a known, planned fault, and we’ve had activity in the past that we’ve recorded, but it’s not a particularly active area.”

Andrews provided some context on how rare moderate to large earthquakes occur in the Kerepehi fault that gives rise to the Firth of Thames and Hauraki Plains.

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“I can give you some numbers. So we’ve only had five earthquakes larger than magnitude 3 in this region in the last 10 years,” Andrews said.

“So they are quite uncommon. But there were 4.9 on the Richter scale in 1972. So we have these earthquakes of magnitude 5. Very rare.”

Andrews explained that the other earthquakes that have struck New Zealand’s North Island in recent months — a 4.1-magnitude earthquake in southern Taranaki on December 26 and a 5.7-magnitude earthquake southwest of Taupo on November 30 — were not related to the Te Aroha noise this morning.

“There was a 3.9 precursor tremor, for the Te Aroha earthquake, on December 29 – so that would be down to the 5.1 that we had this morning,” Andrews said.

“So those are linked but for everything else in the broader New Zealand Pacific region, they’re not linked. It’s just a very active area.”

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Speaking to the Herald earlier this morning, Andrews predicted a possible aftershock like the magnitude 3.9 earthquake that hit the Waikato and Bay of Plenty at 11.29am today.

The most likely scenario is that it will be a few aftershocks and those that diminish over time. There is a small chance that we will see a larger earthquake after 5.1, but the probability of this happening is low and will decrease very quickly with the time of the earthquake.”

The earthquakes are likely to be on the same fault system, as the area was last hit by a strong earthquake in 1972 with the M4.9 Te Aroha earthquake, a reminder that earthquakes can occur anywhere in New Zealand at any time. In the event of a major earthquake: fall, cover and hold. pic.twitter.com/vnuJgo5k9C

— GeoNet (@geonet) January 3, 2023

Andrews said that if another moderate to large earthquake like today with a magnitude of 5.1 were to occur, it would happen in the coming days, or not at all.

There have now been seven aftershocks of magnitude 2.6 or greater since the initial tremor at 5.30am today.

Gary, a Tauranga resident, told Newstalk ZB it kept rolling for about 20 seconds.

Colin Firth also felt the earthquake in Katcatecate.

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“I fell asleep, and woke up to the whole house trembling.”

She said it was loud, and it lasted for about a minute.

A Papamoa resident said she felt the earthquake at 5.49am and shook the entire house.

Other people have taken to social media and Shelly Wood said, “Yeah, I felt bed-shattering!” While Marama Matparai said “Yeah – wake me up”.

Northern Fire Communications said it had not received any reports of major damage or requests for assistance in the aftermath of the powerful quake.

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