South-west Pacific Tremors

Earthquake activity has rippled along plate boundaries in the south-west Pacific since last night’s strong earthquake near Raoul Island. Quakes have been recorded near Fiji, Vanuatu and New Guinea.

The Kermadec quake, initially reported at magnitude 7.0 has been revised down to magnitude 6.8 by the U.S. Geological Survey. This slight adjustment in the estimated magnitude is not unusual as data from more seismic instruments is added to the calculations. On this occasion, the depth of the event has been reduced from 35 km to 14 km.

The epicentre of the quake, which struck at 7:24 p.m. New Zealand Daylight Time on Tuesday the 9th of December 2008, has also been adjusted. The earthquake is now thought to have struck 190 km east of L’Esperance Rock, 220 km south-south-east of Raoul Island (990 km north-east of Auckland). The shallow event occurred on the boundary between the Pacific Plate and Tonga Microplate.

Earthquake activity has subsequently been recorded at several locations on plate boundaries to the north and west of the Kermadec event.

A deep magnitude 5.3 earthquake was recorded in the New Britain area of Papua New Guinea at 10:29 p.m. last night (NZDT). This was followed by a shallower magnitude 5.6 event near the north coast of Papua, Indonesia, at 4:32 this morning.

A deep magnitude 5.9 quake struck off the coast of Ambryn Island in Vanuatu at 6:29 this morning. This was followed by two very deep magnitude 5.1 events in the Fiji Islands, at 7:51 a.m. and 9:09 a.m. NZDT. Both quakes were about 600 km deep, and close to Ndoi Island.

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

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