The United States Geological Survey recorded a Magnitude 6.0 Earthquake at a depth of about 10 km, roughly 160 km to the north of Vanua Levu Island, Fiji, slightly after 4.10 pm local time (slighly after 4.10 am GMT) on Tuesday 15 September 2020. There are no reports of any damage or injuries relating to this quake, but it was felt on Vanua Levu.
The approximate location of the 15 September 2020 Fiji Earthquake. USGS.
The tectonic setting of Fiji is somewhat complicated. The islands form part of the border zone between the Pacific and Australian Plates, with the boundary passing to the north as a transform plate margin, along which the Pacific Plate is moving westwards, relative to Fiji. However, Fiji itself lies on an area of newly forming plate, with an are of expansion to its west, the Fiji Basin, which is pushing Fiji to the east relative to the Pacific Plate. Further to the west the Indo-Australian Plate is being subducted beneath this new microplate along the New Hebrides Trench. To the east of Fiji, a second area of seafloor spreading occurs along the Lau-Colville Ridge, and to the east of that the Pacific Plate is also being subducted, along the Tonga Trench. This means that the islands of Fiji are being subjected to tectonic stresses from several different directions. These stresses do not manifest themselves as smooth movements, but rather sharp jolts which we experience as Earthquakes, as the rocks of the various plates tend to adhere together, only breaking apart once the built-up pressures become to great, and settling into new positions.
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