The Offshore Fiji Earthquake of November 1, 2014 - Magnitude 7.1.The eastern margin of the Australia plate is one of the most seismically active areas of the world due to high rates of convergence between the Australia and Pacific plates. In the region of New Zealand, the 3000 km long Australia-Pacific plate boundary extends from the south of Macquarie Island to the southern Kermadec Island chain. It includes an oceanic transform, two oppositely verging subduction zones, and a transpressive continental transform, the Alpine Fault through South Island, New Zealand. North of New Zealand, the Australia-Pacific boundary stretches east of Tonga and Fiji to 250 km south of Samoa. For 2,200 km the trench is approximately linear, and includes two segments where old Pacific oceanic lithosphere rapidly subducts westward .
At the north end of the Tonga trench, the boundary curves sharply westward and changes along a 700 km-long segment from trench-normal subduction, to obliqu subduction, to a left lateral transform-like structure. Australia-Pacific convergence rates increase northward from 60 mm/yr in the southern Kermadec trench to 90 mm/yr in the northern Tonga trench;
The spreading rate in the Havre trough, the west of the Kermadec trench, increases northward from 8 to 20 mm/yr. The southern tip of this spreading center is propagating into the North Island of New Zealand, rifting it apart. In the southern Lau Basin, west of the Tonga trench, the spreading rate increases the northward from 60 to 90 mm/yr, and in the northern Lau Basin, multiple spreading centers result in an extension rate as high as 160 mm/yr.
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