Wednesday, February 23, 2011

New Zealand Earthquake - They Call it an Aftershock

Article

Seismologists at GNS Science regard this earthquake, large though it is, as an aftershock relating to the magnitude 7.1 Darfield Earthquake that struck Canterbury on 4 September 4, 2010. The technical reason for this is that the epicentre is adjacent to the existing aftershock zone.

It has ruptured over a length of about 17km on a near vertical plane slightly inclined to the south and between 3 and 12km in depth. It is more or less parallel to the E-W trending Greendale Fault that ruptured in the Darfield Earthquake. It may be thought of as an eastern extension but it is clearly dislocated from the trend of the Greendale fault and stepped to the south.

No, this is not an aftershock.  This is a new earthquake marching down the fault.  But who am I?  They are also tossing the old canard that this is a 'safety valve' releasing steam.  Ha!  As well they claim this whole area hasn't had an earthquake for 16,000 years.  blah.

10 comments:

Harbles said...
This comment has been removed by the author.
Harbles said...

Here's some real good photo's of the aftermath.
http://goo.gl/yGmm7

Harold Asmis said...

I'm waiting for the Japanese to come in and give my the PGV's and pictures of buildings that weren't damaged. That 26 story hotel must have been on piles, and the PGV there would have been priceless.

Kevin Tucker, Toronto said...

Have you ever been in an earthquake?

I get this sense that you're disappointed with anything that doesn't absolutely trash a place.

Having been in some biggies, the biggest being an 8.8 in Chile, I can say it's not much fun.

Harold Asmis said...

Thank you for the comment. I don't think anyone else will defend me, but deep down I care more than the platitude bunch.

Harbles said...

Mr.T seems oblivious to the fact that despite the tragedy there is data that can be collected here that may save many lives in the future. The loss of life is tragic but perhaps some good can come from study of this natural catastrophe

Anonymous said...

I think you're a jerk.

Harold Asmis said...

Wow, this is starting to resemble the comments on CBC articles...

Kraks said...

Forgive a geo-dummy...

1. previously unknown segment of a zone of faulting ?

2. a known fault zone growing into an unfaulted area ?

3. the development of a brand new fault ?

4. none of the above...

Harold Asmis said...

There are probably a zillion old faults there. This is following an unmapped fault, that was buried under the thick layer of soft muck. They are calling it strike-slip, but the high ground motions, and the asymmetric aftershocks scream super-shear thrust to me.