Fiji Plate

	Fiji Plate
My Blogs (olelog) are mainly based on my daily reading of earth science news. Here on whatonearth.olehnielsen.dk I try to weave some of the pieces together to a greater whole with added background info.

Plate Tectonics Spreading Ridges Triple Junctions

The Fiji Plate

Fiji is located at the Australian and Pacific plate boundary between two opposite-facing subduction zones and hence has had a very complex tectonic history.

The stresses created by the opposing plate movements have resulted in the formation of transform faults such as the Fiji Fracture Zone to the north and the Hunter Fracture Zone to the south. Seafloor spreading resulted in divergence and opening up of the North Fiji Basin and the Lau Basin. Fiji and Lau are no longer active volcanic island arcs, as there is no subduction or rifting within the Fiji islands, but they formed from similar processes in the past. There is, however, active seafloor spreading occurring at the present day in the Lau Basin to the east and in the North Fiji Basin to the west of Fiji - these are both examples of back-arc or marginal basins.

USGS wrote the following in connection with the M 7.9 Tonga earthquake of 3 May 2006:

Tectonic Summary

The broad-scale tectonics of the earthquake region are dominated by the relative convergence of the Pacific and Australia plates. The Pacific plate subducts westward beneath the Australia plate at the Tonga trench. At the latitude of the earthquake, the Pacific plate moves westward with respect to the interior of the Australia plate at a velocity of about 77 mm/year. The eastern edge of the broad Australia plate may itself be viewed as a collection of small plates or microplates that move with respect to each other and with respect to the Pacific plate and the Australia plate interior.

In terms of numbers of earthquakes, the broad-scale Australia/ Pacific plate boundary is one of the most active in the world. Earthquakes occur on the thrust-fault boundary between the Australia and Pacific plates, within the Pacific plate, and within and on the boundaries of the small plates that together compose the eastern edge of the overall Australia plate. On the basis of currently available information, we infer that the earthquake of May 3, 2006, occurred within the subducted Pacific plate

Fiji plate treated in Olelog

p.m.

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