Quake similar to June and should taper off - GNS

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Fri, 23 Dec 2011 8:18p.m.

GNS says today's sequence of quakes was kicked off well over a year ago

GNS says today's sequence of quakes was kicked off well over a year ago

Earthquake scientists say Christchurch could face further aftershocks in the coming days but the shakes will probably taper off quickly, as they did in June.

But they say what is happening in Christchurch only occurs every few thousand years, and that makes the earthquakes difficult to predict.

This afternoon's 5.8 quake, centred 20 kilometres north-east of Lyttleton, set off yet another swarm of shakes across Canterbury.

It struck at 1:58pm at a depth of 8km and a 5.3 quake struck eight minutes later.

Then the biggest of the afternoon, a magnitude 6.0 jolt recorded just 6km deep and centred 10km east of the city.

GNS seismologist Ken Gledhill says the sequence was kicked off by the September 2010 event which “changed the earth under our feet in Christchurch”.

“This series of earthquakes as a result of that, including the February and June one, this is almost a rerun of the June one.”

What is happening in Christchurch only occurs every few thousand years, so there is little to go on in terms of predicting what is next.

Still, GNS says the quakes are all part of the earth's re-adjustment after the original quake in September 2010.

“But that process is not taking place in what we call a classic aftershock sequence,” says Mr Gledhill. “It's rather a series of earthquakes over a much longer period of time.”

GNS says today's cluster of quakes is not unusual and they should settle quickly.

“If you think of what happened in June; you had a couple of quakes nearly magnitude 6.0 or around 6.0, and then you had a tailing off in the next few days – that’s the most likely scenario.”

So after a period of relative calm, for the city and its people the process of settling down begins, again.

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Comments

23 Dec 2011 10:28p.m.

Mark wrote:

Jesus we know the drill after 8000+ with 4 massive ones..but they dont seem to stop..the threat of a big one will happen at anytime is the man issue and will also plague those who have lived through this year in chch