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Christchurch earthquakes

 Update March 2015

All seems fairly quiet on the eastern front, we have had a few minor tremors over the past few months, and like most people, I have not noticed them and they have not caused any concern.

Update November 2014

Actually few people remember the last aftershocks as there have been a few minor tremors in 2014, however earthquake activity seems to be moving away from Canterbury. Geonet has the latest earthquake data.

Update June 2014

The Christchurch earthquakes continue to subside. The significant quakes have been nearer Wellington and far to the north near of New Zealand. The Christchurch rebuild is well underway and the city is very busy, and the cross city traffic horrendous.

chchshake

A photo of the city moments after the February 22nd, 2011 earthquake from the hill suburb of Cashmere.

Update November 2013

Since the Wellington earthquakes (21 July 2013 M 6.5 off the coast near Seddon and the 22 July M 5.2 aftershock) off the coast of Marlborough, irregular shakes up to M 4.5 are still occurring in Canterbury. This indicates that the land or rather the tectonic plates are moving more quickly than they have for thousands of years and may be tied into the increasing severity of other land and climatic events like typhoon Hiayan.

Update February 2013

Earthquakes in Christchurch  New Zealand continue although they seem to be declining in frequency and intensity. There are other infrequent shakes around the Pacific rim, many strong as the +8 near Vanuatu a week ago.  This brings the questions;

  1. are we hearing about these shakes as the recording and communication technology  has improved or
  2. is tectonic plate movement increasing?

Update May 25th 2012

The earthquakes continue with a 5.2 shake of Brighton this afternoon. It was not strong enough to disrupt the massage in progress.

It recently dawned on me that as the Pacific Plate is moving south west, it’s movement is impeded by the hard volcanic basalt of Banks Peninsula. It seems that the Sept 2011 quake cutting over the Canterbury Plain creating the Greendale fault caused by the south side moving more quickly than the held up land to the north. While this is only an idea, it would gain weight if the earthquakes of New Brighton are compression fractures. If this all correct, earthquakes will continue for many years as Banks Peninsula continues to impede the Pacific Plate progress.

Update March 2012

Minor earthquake activity continues with occasional small tremors which largely go unnoticed.

Update June 17th 2011

Canterbury continues to be rocked by earthquakes causing more damage and concern. The latest 6.3 shake on June 13th was located near the port of Lyttleton and the most damage was to the port and the city eastern suburbs however life returns to normal for most while those hardest hit endure weeks of cleaning up with limited services. The airport is open and essential services are stretched.

Scientists are now betting that there is a 70% likelihood of similar earthquakes in the region over the next two years, so if you want to experience and earthquake, come visit.

May 19th  2011

Life is returning to normal for the majority of Christchurch residents. Parts of the central city are re-opening and everyone is complaining more about the cost of living and other worries than earthquakes. There are still many frequent tumours with a total of 2275 since Sept 4th (past 105 days which equates to 21 earthquakes per day), however they are spread over a wide geographic area from Blenheim to Westport, Wanaka and the Southern Alps with the Mid Canterbury getting the most.

Locally, getting about is still slower with a great deal more traffic congestion and about the city contractors are busy carrying out repairs.

Its interesting to view The Christchurch Quake Map which from Sept 4th takes hours to run and it seems obvious that the two faults, Greendale and Lyttleton have yet to meet and the Lyttleton fault is extending out into the continental shelf. So rumour rather than any scientific prediction says the earthquakes my be with us for another year or two.

An observation:
The Sept 4th earthquake was centred under the Canterbury Plain miles from Christchurch city and the earthquake was relatively gentle. The 2nd major shake was across the side of and extinct basalt volcanic area nearer the city. Although the 6.2 shake was less, it  was far more violent as it was closer to the city and the fracturing of the brittle basalt produces a far more severe shock than sediment. Future shakes on this principal will be less severe and 9ndeed, the past 4 - 5 shakes have been very mild.

April 26 2011
Following the severe earthquakes of September 4th and February 22nd 2011, the city infrastructure is severely damaged and the dead number over 160. An estimated 70,000 people who lost their homes and businesses have fled the city.

The city however is not dead, life has returned to normal and despite the occasional tremor or aftershocks, there is fuel, food and motel accommodation. Suburban malls, service stations and supermarkets to the north, south and in the western suburbs are open although queues are sometime longer than normal.

If Christchurch was on your itinerary, the airport is open. Call in as all the tour operators are still in business and the city is still a good place to base your South Island adventures..

Key points:

  • The central city and business district has restricted access
  • Many central city streets remain impassable
  • Expect a normal 10 minute journey across the city by car or bus to take 3 - 4 times as long during peak hours.
    If you can, avoid cross city travel from 8.00 - 10.00am and 3.00 and 6.00pm.
  • The city bypass routes are open with few problems
  • The airport is open with all regular flights operating.
  • If you were planning on spending time in the city, please check with your travel agent as some tourist attractions remain closed.

Previous Earthquake - Saturday September 4th 2010
The 7.1 magnitude earthquake caused moderate damage to older buildings in the city and suburbs, however most services returned to normal within a few days and over a week later, the aftershocks are diminishing and life was returning to normal.

Is it over?

Ask Ken Ring; Known as the "moon man', Ken is a specialist in weather forecasting based on the lunar cycles predicts there will be more shakes before its all over. If you don't want to feel the earth move, perhaps you should avoid the region around the full moon. Ken is not alone in these predictions and some think that the faults created by the two big shakes have yet to meet.

February 22nd 2011

TV News View including some smaller aftershocks while filming after
A Magnitude 6.3 Earthquake has hit Christchurch, New Zealand, at a depth of 5 km and centred 10 km south-east of the city.
There are reports of major damage to buildings and infrastructure and much of the inner city was closed to public access.

Update, December 12th 2011

Earthquake activity has reduced and since September, there have been few significant tremors and it seems that the earth is returning to it normal calm and local residents have resumed their lives and rebuilding.

Update August 10th 2011

Like many of you,our home and business has been damaged, but not enough to make us move, actually it made the clinic a little bigger, but as to the repair work, who knows when it will happen?

On the earthquake front, running the meter showed our shakes are reducing, a total of 28 last week which is a big drop from the sometimes plus 30 per day.

Christchurch Residents Update June 23rd 2011

The government announces a buy out package for those in the red zone and expects they should be able to purchase a new home somewhere else within the next 8 weeks.

The site to refer to is landcheck.org and another reference is the tvnz map.

The Canterbury Earthquakes Learning Corner

On average there have been around 25 earthquakes every day, (7336 from Sept 4th 2010 to June 14th 2011) beginning with the 7.1 on September 4th 2010 which opened a gap in the Canterbury plain known as ‘The Greendale Fault’ and following this there were many more smaller earthquakes not only in Canterbury, but over the entire region from Otago to Marlborough and Westland with many deeper shakes under the Southern Alps. The earthquakes continued into 2011 with the most devastating being the February 22nd 6.3 shake which severely damaged Christchurch city and it’s infrastructure.

The key differences in how we felt the Sept 4th and Feb 22nd shakes is this; the Sept 4thwas centred under the Canterbury Plain, a region of sedimentary gravel washed down off the mountains over thousands of years, consequently, the earthquake was relatively ‘soft’ due to the soft nature of the land.

The Feb 22nd shake created a tear across the side of the port hills, this is hard, brittle basalt – by way of analogy’ its like contrasting the breaking a soft slightly stale cookie and a crisp fresh one. You can feel the difference and its simply a matter of contrast between the properties of soft and brittle which is how I explain why the Feb 22nd shake was felt more severely than the Sept 4th as well as the epicentre of the Feb 22nd shake being closer to Christchurch city.

Everyone hopes that these earthquakes will diminish and stop, and the 5.6 and 6.4 on June 13th came as a surprise to many however there is more going on in our region than many are prepared to consider while the experts are very coy and not giving any clues to what is going on perhaps out of fear of causing more paranoia .. a bit like not telling someone their house is on fire in case they get upset. Note there will be a full moon on June 16th.

The future
Scientists say these earthquakes will continue for some time – possibly two years or so as they slowly diminish. So lets look at what is happening to our patch of Earth. We have the Greendale and Port Hills Faults (these two faults appear to want to join) – we also have an increase in activity out into the ocean and most unusually there is a highly active shake centre where there have been hundreds of smaller earthquakes near Oxford. I agree, these earthquakes are far from over .. I would love to see what is happening to the elevations of the land – is it rising or falling due to earthquakes and seismic activity?

So really, these earthquakes will continue for some time and the closer you live to the faults, the more severe the shakes will be. Shakes on the plains will be less severe than those about the port hills and as I am writing this the house shakes again..

What to do?
Be prepared – pack away breakables and get on with life. We live at time of global strife, there is nowhere to run, nowhere to hide and in the words of Dr John Demartini; It may seem that a situation is a loss without gain, destruction without construction, but this is not the whole truth, for ignorance blindly sees only one side. History has taught us that out of the ashes rise great opportunities and that any challenge can be transformed when we know how to ask a new set of questions and shift our perceptions and then actions.

Why do we have earthquakes and is the ‘moon man’ right?

Humanity has no need of earthquakes and probably has no influence over them although some argue that testing nuclear bombs and global warming may be possible causes. Nuclear bomb testing as far as I know has stopped and seems an unlikely cause as the shock at the epicentre of the bigger earthquakes is many times the explosive force of a nuclear bomb.

It appears that we have three types of earthquake.

  1. Tectonic plate movement
    This is geological, the interior of the earth is liquid rock or lava that circulates underneath the earth’s crust which in scale is like the skin on a custard. The earth’s crust composed of rock is continually moving as sections called tectonic plates press against each other which causes mountain ranges to form. In NZ as the Pacicic plate pushes against the Australian plate, the Southern Alps are pushed up and in Asia, The Indian plate moving north causes the Himalayas to rise up.As often happens, one plate is sliding slowly under another, sometimes millimetres or several centimetres per year. This is not a smooth process, the rocks stick to each other and pressure builds. When the pressure is to great for the rock to remain stuck, the rock breaks releasing the pressure and the tectonic plate moves. This is the most common type of earthquake and the recent big earthquake in Japan is a consequence of this tectonic plate movement.The earthquakes in New Zealand are compounded by techtonic plate forces as the Pacific plate moves at a differnt speed in different places although lunar and interplanetary gravity may have a role in triggering earthquakes.Tectonic plate movement also causes volcanoes as the tectonic plates slide over each other.
  2. The tide and lunar influence
    The earth’s crust is accustomed to the weight of the ocean continually pressing down (1.37 X 1021kg), but its a huge load which is continually moving and this movement is caused by the moons gravity. Under this weight of water, as the tide moves, the earth’s crust flexes a little and this I expect could trigger the release of the stuck tectonic plates as described above. The weight and movement of the oceans pressing down through the earth’s crust will influence the circulation of magma under the earth and the gravity of the moon may also have an influence in keeping our molten interior moving. Now when there is the combined force of a king tide where the tide my be half a metre or more higher than normal which adds billions of tonnes additional pressure onto the earth’s crust combined with the moon being closer than normal to earth and having a stronger gravitational effect, the possibilities of earthquakes must surely increase. Its simple common sense that when something is overloaded, it may break and it can break in the moment of greatest pressure, or silently fracture and break days or months later. So in this the moon man is correct and after the 5.1 shock on Sunday evening (March 19th) and the 5.3 shock on April 16th, many sceptics will be less sceptical. The moon man is not a magician and has no special powers, all he does is use publicly available information to say that there are times such as during king tides, lunar and planetary alignments, that the earth will be experience to greater stress.
  3. Volcanic
    Hot spots under the earth’s crust force there way up to erupt causing earthquakes in the process, I see this as different to the volcanic activity caused by tectonic plates sliding over each other.

What can we do?
Take the warnings in good heart, but never panic. Be prepared and have a few days water and supplies in store. We have lived with earthquakes and tsunamis and these things are facts of life as much as old age, death and taxes. Be philosophical about life and be grateful your still alive.

Travel preparedness

References
Geonet
Ken Ring's predictions
TVNZ
TV3 News
Christchurch Quake Map
Christchurch City Council
Police Earthquake Info

 

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