A large deep magnitude 6.4 regional earthquake to the north of the Kermadec Islands occurred 10:28am this morning. This is the 2nd large quake within the last 24 hours, with a magnitude 6.5 occurring yesterday in the same area on the Tonga trench. The primary seismic wave from today's quake arrived onto the upper North Island 3 minutes and 39 seconds after the fault rupture but would not have been felt by humans.
The Pacific Plate is subducting under the Australian Plate, which forms the Tonga, Kermadec and the Hikurangi trenches and uplifts eastern parts of New Zealand's North Island. The plate boundary then continues and connects to the South Island's Alpine fault.
Image courtesy of USGS.