An intriguing series of shallow earthquakes in the last week including two M5.1 yesterday, 730km NE of the Hauraki Gulf. They are in the same area as the Havre submarine volcano within the northern segment of the Kermadec Arc. There are no signs of a volcanic eruption at this stage but earthquakes at this depth and vicinity suggests volcanism unrest can't be ruled out.
The submarine volcano last erupted on 18 July 2012 in what was one of the largest deep-sea eruption in over a century. This was followed by an active a period for North Island volcanoes with a White Island eruption on 5 August 2012 followed the next day by an eruption at Tongariro's Te Māri crater.
Further background video from GeologyHub