Solomon Islands Aftershocks Continue

Aftershocks following yesterday’s magnitude 7.2 earthquake near Gizo are continuing. In addition to the 6th magnitude foreshock, there have now been seven aftershocks of magnitude 5 and one of magnitude 6.

Tuesday 5th January 2010

Yesterday’s magnitude 7.2 earthquake near Gizo in the Solomon Islands has been refined slightly, following further analysis of seismic data. The epicentre of the quake is now thought to be located 95 km south-east of Gizo in the New Georgia Islands at a depth of 25 km.

Aftershocks are occurring as expected, with ten being recorded since the magnitude 6.5 foreshock at 10:48 a.m. and the main quake at 11:36 a.m. New Zealand time. Examination of the seismic traces has allowed the onset of the event to be timed a few seconds earlier than first thought, bringing the general timing forward by a minute to 11:36.

Ten aftershocks had been recorded by early afternoon today. They include seven quakes with magnitudes between 5.1 and 5.8 and two of magnitude 4.7 and 4.8. The largest aftershock to date, a magnitude 6.1 earthquake, struck at 28 minutes after midnight this morning, New Zealand time. This was centred 35 km south-east of Gizo at a depth of 35 km.

Most of the aftershocks have been shallow events, at depths between 12 and 38 kilometres. They are occurring undersea in an area ranging between 35 and 135 km from Gizo, generally in the south-east direction. The latest aftershock, a magnitude 5.1 quake at 25 minutes after midday was much deeper at 85 km.

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

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