Christchurch Boxing Day earthquake explained

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Fri, 03 Jun 2011 6:05p.m.

Researchers use sonar equipment which also found the Port Hills fault

Researchers use sonar equipment which also found the Port Hills fault

By Jeff Hampton and 3news.co.nz staff

Scientists have found a new active fault lines in Canterbury.

Geologists and seismologists from GNS Science, NIWA, the University of Canterbury, University of Otago and University of Calgary all contributed to the Natural Hazards Research Platform.

The research is aiming to find out what is going on below Canterbury's ground by understanding the patterns of aftershocks.

Speaking at a press conference this afternoon, the scientists say they have uncovered a fault line in central Christchurch under Barbadoes Street and another off the coast of Pegasus Bay.

The Pegasus Bay Fault is 25 km in length and is capable of generating a 7.0 magnitude earthquake.

They say this fault is of particular concern as it is considered the greatest risk for another large quake but they are urging people not to get the jitters.

The new faults are not obvious like the Greendale one which hit in September. These ones are deep underground and rarely active.

One recently discovered fault line caused the 5.3 magnitude Boxing Day shake and lies underneath Barbadoes Street just east of the central city. It has been quiet since then.

The University of Canterbury’s professor Jarg Pettinga says the group of scientists will never know the complete answer but “the fact that it isn’t very busy with aftershocks is a good indication”.

Researchers using sonar equipment which found the fault, also used the same technology at New Brighton where they investigated the Port Hills fault, which caused February’s devastating quake.

Other research has been done from the NIWA research vessel Kaharoa which found the previously unknown Pegasus faultline.

But there is no sign the after-shocks have reached this new fault line and the faults here move slowly with a long time between shakes.

At the press conference Canterbury Earthquake Recovery Minister Gerry Brownlee also revealed the likelihood of a major earthquake in Christchurch is currently similar to that of Wellington.

“The discovery of faults that are six to nine million years old, which have low rates of movement, is pretty encouraging,” said Mr Brownlee.

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Comments

06 Jun 2011 01:13p.m.

malco wrote:

I wouldn't be so quick to belittle the scientist's efforts to discover what is happening. The plate boundary is an incredibly complex system with broken "fragments" all over the place, some moving alongside each other and in other places subducting as well. Understanding how the general pressure from the mid-ocean ridges where new crust is forming and exerting outward pressure is applied to the general boundary line may lead in future to a better understanding of where that pressure is building through bits temporarily sticking together and then releasing a large amount of energy when the pressure overcomes the friction and movement occurs.
It is easy to write off research when future benefits are not immediately obvious. The laser was a "solution looking for a problem" and just look how prolific the uses are now. I suppose one could argue that knowing where the next earthquakes will occur and what their effects will be is pointless given that people are living in these places and won't move (until the earth does) but lives may well be saved if and when enough is known. Were it not for the innate curiosity of some people we would still be living in caves. Everything is "obvious" after the fact.

05 Jun 2011 12:16p.m.

Roxanne wrote:

Amazing how clever they are after the fact and does knowing this stuff actually enrich our lives? They could pack up and go to Wellington and do this "research" and it would tell the population there what they already know as well.

04 Jun 2011 07:43a.m.

Steve wrote:

"Jarg Pettinga says the group of scientists will never know the complete answer............" Well, that will keep them employed for a damn long time then!

How does Brownlee know the age of these fault lines? Can Brownlee also then give us a likely date for a major earthquake both here and Wellington? Does he need to go and talk to Ken Ring for those answers?

04 Jun 2011 05:24a.m.

Glenn wrote:

Fault lines are everywhere. These scientists get paid big bucks to tell us this?

03 Jun 2011 09:40p.m.

jj wrote:

What would a flower grower know about earth quakes,other than they shake the ground and causes destruction, as he said the likely of a major earthquake in Christchurch is currently similar to that of Wellington.Not bad for a huge guy like him to know that flowers have a stem leaves and a head.Is he one of those new trained scientists that Key put huge amounts of money into for developement.

03 Jun 2011 08:24p.m.

ami wrote:

Puts paid to earlier reports in the media that the quakes were a result of "NEW" faults. There are many fault lines either undiscovered or forgotten about.
A few years ago I was told by someone that there are fault lines that run through Dunedin. When I look at a specific road mentioned that runs up between two hills near Carisbrook, I wonder at how many "NEW" faults are yet to be rediscovered.

03 Jun 2011 07:04p.m.

kane wrote:

scientists found fault line under CHCH city Oh really wouldn't of guessed that... Amazing facts they come up with... Well their computers and software come up with...