Geologist says back-to-back major earthquakes off New Zealand coast 'a bit unusual'

Back-to-back major earthquakes under the Pacific Ocean off New Zealand this morning are "a bit unusual", a geologist says, but it's not clear if one triggered the others.

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John Ristau says it's hard to say if the quake off the cost of Hawke's Bay overnight triggered jolts near the Kermadec Islands. Source: Breakfast

A quake, which struck at 2.27am, 105km east of Te Araroa at a depth of 90km, was felt by over 52,000 people around New Zealand. Evacuations on parts of the North Islands east coast were in place, but were later lifted.

But a later tsunami evacuation warning was put in place for parts of the North Island’s east coast after the Kermadec Islands was rocked by a second major earthquake later this morning, this time a magnitude 8.0 quake at a depth of 10km.

The quake struck at 8.28am, prompting Civil Defence to issue the tsunami warnings for parts of the North Island's east and west coasts.

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The first quake to strike the Kermadecs this morning was a 7.4 shake at 6.41am.

GNS seismologist John Ristau told Breakfast it's hard to say if the quake off the coast of Hawke's Bay overnight triggered jolts near the Kermadec Islands.

"To have them come one right after the other like that, yeah, that is a bit unusual," Ristau said.

He said earthquakes around the Kermadecs wasn't unusual in itself, though, with similar events every few years.

"But yes, to have them sort of bang, bang like that, that doesn't happen very often."

However he added that it "would be very hard to read anything into it" as the greatest risk of a big earthquake is immediately after another one.

"Now, did this one (near Hawke's Bay) trigger the one at Raoul Island? That's a thousand kilometres away or so, so it's quite a bit of distance - hard to say for certain if it did, you know, that would require a lot of work to really look into that to find out if it did."

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