Increased Quake Activity in the Kermadecs

Earthquake activity in the Kermadec Islands increased during the latter part of the week.

An unusual quiet period followed last Sunday’s massive earthquake north of Raoul Island in the Kermadecs. The 150 km-deep quake had a magnitude of 7.8 but aftershocks, which would normally follow a quake of this size, did not occur for several days.

Activity picked up on Wednesday morning, December 12th 2007, when a magnitude 5.1 quake struck 105 km south of Raoul Island at 6:46 a.m. This quake was followed by a magnitude 5.0 event nearby on Thursday afternoon.

Activity returned to the vicinity of Sunday’s quake when a magnitude 4.9 quake struck 305 km north-north-east of Raoul at 4 p.m. and a magnitude 4.8 quake struck during Thursday evening.

Another burst of activity was recorded to the north of Raoul Island this morning when a pair of quakes struck between Raoul Island and Fiji’s Ndoi Island. The magnitude 4.7 quake was 400 km deep, and a subsequent magnitude 5.1 event at 7:25 a.m. was much shallower at 29 km.

Earthquake activity has occurred further north as the plate boundaries react to altered stress following the large quake. A magnitude 5.2 quake struck near Tonga on December 13th and a magnitude 6.2 earthquake near Samoa on the same day.

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

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