A series of eight earthquakes along a 600 km stretch of the Kermadec Ridge north of New Zealand commenced on December 2nd. Between the 2nd and the 12th, three events in the magnitude 4 range, four events in the magnitude 5 range and one event of magnitude 6.4 were reported by the United States Geological Survey. All but one, which was 173 km deep, were at depths of 46 km or less.
The Kermadec Ridge, which includes Raoul Island, sits above the subducting Pacific Plate. The area is also part of what is known as the Tonga microplate, a plate fracture zone which extends from the eastern North Island to south of Western Samoa and the area east of Fiji.
Two other events in this microplate area (magnitude 4.1 and 4.0) occurred nearer New Zealand on December 2nd and 5th.
Yesterday’s magnitude 6.7 earthquake between Fiji and Wallis & Futuna occurred near the northern edge of the Tonga microplate.