WELLINGTON - Seismologists say a recent swarm of earthquakes in central and southern North Island areas is not building up to the big one - as far as they know.
The Bay of Plenty was shaken on Wednesday night by a tremor measuring 5.4 on the Richter scale as well as a series of short, sharp, shallow earthquakes, the largest of which was only magnitude 2.9, Institute of Geological and Nuclear Sciences seismologist Ken Gledhill said yesterday.
The bigger quake was centred 10km west of Edgecumbe and was 147km deep. The series of smaller quakes, affecting an area around Ngongotaha, 8km northwest of Rotorua, were weak but shallow so people felt them sharply, Dr Gledhill said.
In the past three weeks, six earthquakes, two of about 5.5 magnitude, had shaken the Wanganui area. While it was unusual to have two quakes of that magnitude close together, they had been deep and were unlikely to be a precursor to a shallow, damaging earthquake, he said.
"The depth is quite important. It means they're quite a long way away from you, even if there is something bigger. It's the shallower ones that cause the major damage."
New Zealand had had a relatively quiet period for large earthquakes and it was possible - although not likely - that the recent activity might be building up to something. The difficulty was distinguishing a series of unconnected earthquakes from a connected series while they were happening, said Dr Gledhill.
"The trouble is we don't really know. We can only look over very long time periods, over which things ebb and flow."
- NZPA
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