Wellington Earthquake warning ! - New Zealand

[Flux]

Was felt like a gentle rolling wave. My place just wobbled a little.

[The Matrix Traveller]

Was felt like a gentle rolling wave. My place just wobbled a little.

Hi Flux,

Thank you for your Valued feedback...

Feedback is very important, so we can get a true picture on what's going on.

[Flux]

Nice to have you back Matrix

Never heard it coming just felt the movement as described. Lasted for about 10 seconds.

[The Matrix Traveller]

I think the reporting of some of these seismic events, are slightly overrated  from what I see.

It sounds like the Moderate Earthquakes should be referred to as Light Earthquakes instead.

Perhaps they should rate Earthquakes on "Ground Surface Acceleration" rather than "Magnitude" ?

Then we might get a truer idea of the impact of these Earthquakes on our lives ?

[The Matrix Traveller]

Another 2 very Shallow Earthquakes last night..

One 20 km north-west of Pongaroa and only 5 Km Deep

Public Id: 2014p028898
NZDT: Sunday, January 12 2014 at 5:36:56 am
Maximum intensity ?: moderate
Depth: 5 km
Magnitude: 3.4
Location:  20 km north-west of Pongaroa

The Location of Pongaroa shown by a RED flag in the Sat. Image below

The 2nd very shallow Earthquake, only 5 Km Deep, was 15 km east of Ruatoria

Public Id: 2014p028372
NZDT: Sunday, January 12 2014 at 12:56:49 am
Maximum intensity ?: moderate
Depth: 5 km
Magnitude: 3.4
Location:  15 km east of Ruatoria

The Location of Ruatoria shown by a RED flag in the Sat. Image below

[The Matrix Traveller]

Yet another Very Shallow Moderate Earthquake only 5 Km Deep 3.3 Magnitude
40 km west of Milford Sound

Public Id: 2014p031061
NZDT: Monday, January 13 2014 at 12:49:24 am
Maximum intensity ?: moderate
Depth: 5 km
Magnitude: 3.3
Location:  40 km west of Milford Sound

The Location marked by the RED "flag" on the Sat. Image below

A photo of Milford Sound...

40 km west of Milford Sound, places the focal location of this Earthquake, off the West coast of the lower end
of the South Island, where most of the Moderate Earthquakes are taking Place at present, apart from couple
in the North Island recently.

I would love to get a Geological picture of WHAT is exactly happening at this Shallow Depth
with regard to land movement and the mechanics of HOW the Earthquakes are being caused.

i.e. are their cavities involving subsidence in the earth at this depth, or are these earthquakes
being caused by a Shear action ?

HOW much movement and WHAT amount of land (Length) is involved  in a localised area
would take place, to produce these Earthquakes ?

We are only told the Magnitude and Focal area !  If some length and depth is involved
in these shear actions, HOW do they determine a focal location ?

Is it taken from the average location of the seismic activity or the Most intense location or what ?

And especially the Ground acceleration involved both at the source and at the surface ?

[zorgon]

NZ's plate boundary zone

Almost all of New Zealand is in the deforming plate boundary zone, where reasonably steady deformation is occurring all the time.

Plate boundary zones are the zones of interaction between adjacent plates where they collide, pull apart or slide past each other. These zones may be anything from a few kilometres to a few hundred kilometres wide.

It is the motion between these two plates, and the deformation that occurs in the boundary zone between the plates, that has given rise to much of New Zealand's geology as we see it today. The deformation and squashing caused by the collision of the two great plates has caused mountain ranges to rise throughout the country.

Some mountain ranges are still rising, and the interplay between the tectonic forces pushing the mountains up and gravity trying to pull them down means that landslides are a common occurrence over much of New Zealand.

Deformation is also the fundamental cause of the earthquakes and volcanic eruptions that are such important natural features of New Zealand.

http://www.gns.cri.nz/Home/Our-Science/Earth-Science/Plate-Tectonics/NZ-plate-boundary

[zorgon]

Deformation of New Zealand

Reasonably steady deformation - squashing, stretching, rotation and twisting - is occurring in the plate boundary zone all the time, even during the time periods between major earthquakes.

These deformations, which amount to less than 1 millimetre per kilometre each year, are very small. But over tens or hundreds of years, and over distances of tens or hundreds of kilometres, they build up to amplitudes of many metres. It is generally when the deformation has built up to large levels that the rocks of the Earth's crust can't stand the strain any more, and the rocks break as earthquakes along geological faults.

http://www.gns.cri.nz/Home/Our-Science/Earth-Science/Plate-Tectonics/Deformation-of-NZ

[zorgon]

Measuring deformation

A combination of continuous GPS at widely separated sites and occasional GPS surveys in dense regional networks is used to monitor New Zealand's deformation.

By analysing many repeated historical survey measurements, scientists in New Zealand had by the mid-1980s put together a picture of how the country - squished within the Australian-Pacific plate boundary zone - is deforming today. But this was a picture based on 100 years of survey measurements, which only gave an average picture of the deformation over the last 100 years.

The development of Global Positioning Systems (GPS) in the early 1990s allowed scientists and geodetic surveyors to make repeat GPS measurements at many hundreds of points throughout New Zealand.

Today, continuous GPS is used to permanently and continuously monitor deformation in near real-time.

http://www.gns.cri.nz/Home/Our-Science/Earth-Science/Plate-Tectonics/Measuring-deformation

[zorgon]

[zorgon]

Showing the future shape and deformation of New Zealand if the deformation measured between 1994-1998 were to continue unchanged.



http://www.gns.cri.nz/Home/Learning/Downloads/Plate-Deformation-Animation

[zorgon]

[The Matrix Traveller]

According to GNS Science NZ....

One part of NZ in the South (South Island) the Australian plate passes UNDER the Pacific Pate
while in the North Island the Australian Plate passes OVER the Pacific Plate ? ? ?

While in the Centre of the North Island the Plates are Pulling apart !

Sounds rather Tangled to me...



https://ncealevel2sci.wikispaces.com/file/view/plate+tectonics+for+extreme+events.pdf

[The Matrix Traveller]

The Opening of the Tasman Sea: A Gravity Anomaly Animation

C. Gaina,1 School of Geosciences, Division of Geology and Geophysics,
University of Sydney, Sydney, Australia
E-mail: carmen@es.su.oz.au
W. R. Roest, Continental Geoscience Division, Geological Survey of
Canada, Ottawa, Canada
E-mail: roest@agg.NRCan.gc.ca
R. D. Müller, School of Geosciences, Division of Geology and Geophysics,
University of Sydney, Sydney, Australia
E-mail: dietmar@es.su.oz.au
P. Symonds, Australian Geological Survey Organisation, Canberra,
Australia
E-mail: psymonds@selenite.agso.gov.au

http://www.earthbyte.org/Resources/Movies/ei021.pdf

[The Matrix Traveller]

http://www.teara.govt.nz/en/map/5607/basins-troughs-and-trenches