Island Watch: Quakes Near Vanuatu, Fiji, Tonga

A pair of 5th magnitude earthquakes near Tonga late on February 5th NZ Daylight Time were the latest in a series of earthquakes to strike near Vanuatu, Fiji, Tonga and the Kermadecs in the past week.

Following a fortnight of relative calm, earthquake activity in the islands picked up during the latter part of January, with quakes near Vanuatu and Tonga on the 23rd (see item dated January 24th).

Three very deep earthquakes with magnitudes between 4.4 and 4.7 then struck at depths between 460 km and 560 km in the Fiji region on January 28th, with a magnitude 4.6 quake at 118 km depth near Tonga on the same date. Another event of magnitude 4.6 struck at 107 km depth near Tonga on the 29th.

Deep activity near Fiji continued on January 30th and 31st, with three quakes with magnitudes between 4.3 and 4.8 at depths between 520 km and 575 km.

A magnitude 4.6 quake struck at a depth of 181 km south-east of the Loyalty Islands on the 31st, followed by a magnitude 5.2 quake further north near Vanuatu at a depth of 246 km. The day’s big event was the magnitude 6.5 quake at a depth of 54 km near Raoul Island in the Kermadecs, which was followed by a magnitude 4.9 quake at a depth of 77 km in the Santa Cruz Islands, to the north-west of Vanuatu in the Solomon Islands.

Activity then eased until a magnitude 4.8 quake struck at the very great depth of 637 km in the Kermadecs on February 3rd.

Yesterday’s earthquakes were situated north-west of Tonga’s capital Nuku’Alofa. The first quake of magnitude 5.7 struck at 10:56 p.m. on the 5th of February 2007 (NZDT) at a depth of 77 km. Twenty minutes later a magnitude 5.6 quake struck nearby (60 km NNW of Nuku’Alofa) at a depth of 15 km.

[Compiled from data supplied by the US Geological Survey and its contributing agencies.]

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