Geonet seismologist John Ristau says it's unusual to have three major earthquakes within hours of each other

But he says the two near the Kermadec Islands are connected in being the same type and location.

Ristau says it's the type of earthquake right on the boundary between two plates.

He says through the Kermadecs and all the way under the North Island, the Pacific Plate is pushing under the Australian plate.