The deep south?

Maybe some people up north see everything south of Wellington as ‘the deep south’, but when Otago is referred to as the deep south it bemuses me.

Stuff: Otago’s defence stands tall in successful Ranfurly Shield raid against Waikato

The Ranfurly Shield is heading to the deep south for the summer as Otago matched their successful 2013 raid in Hamilton by holding on for an enthralling 23-19 win against Waikato in the Mitre 10 Cup.

It seems similar to including Auckland in ‘the far north’. Otago to me is just Otago.

If there is a ‘deep south’ then surely it is Southland. Or Fiordland.

ODT:  NZ’s most remote place is in the deep south

Where do you go in New Zealand to be farthest away from civilisation?

Hamish Campbell, a software engineer who works at Koordinates in Auckland, said he used a range of open-source data tools to pinpoint the place which was farthest from any structure, including far-flung conservation huts.

He started by using a Land Information NZ map which showed the location of every building in the country – 653,358 in total.

That quickly narrowed his search to Fiordland, on the south-western edge of the South Island.

After a bit of digital wizardry, he found what he believed to be New Zealand’s most remote spot. It is the south end of a bay which the Coal River empties into, and is south of Doubtful Sound.

Fiordland is certainly the most inaccessible region in mainland New Zealand, except by boat or by helicopter.

But parts of Otago are further south than the bottom of Fiordland, and further south than Invercargill, and further south than Bluff.

File:Position of Otago.png

 

That shows Otago stretching almost as far south as the southernmost point of the South island, Slope Point (incidentally the southern Catlins is a great area to visit).

It also shows that Lumsden is north of Dunedin! And Kaka Point is about as far south as Riverton, and Milton is as about far south as Gore, and Tuatapere is north of Balclutha.

Quite a lot of Otago is north of parts of Canterbury. Lakes Wanaka and Hawea are completely north of parts of South Canterbury. Makarora is actually north of Timaru (about the same latitude as Temuka).

But to me Otago generally is not the far south. That’s Southland. We are just south-ish.

Retrolens historic images

This may be of interest to some people – a library of historic aerial photographs, currently for the Waikato, Bay of Plenty, Hawkes Bay, Nelson, Malborough, Canterbury and Southland.

Retrolens Historic Images – Map

Also on aerial images, I see that Google Maps have updated images, at least of my area. It’s interesting to see new plantings and growings and cuttings and landscaping.

From Retrolens About:


Retrolens is made up of a treasure trove of aerial photographs that have been taken since the 1936 through to 2005. It is a Crown archive and contains 500,000 images.

This Historic Image Resource came about as the result of a scanning project that was started in 2015 by partnerships between the Local Government Geospatial Alliance (LGGA) and Land Information New Zealand (LINZ). The two organisations were concerned that the treasure was deteriorating and with fewer and fewer scanners worldwide able to read the images, something had to be done quickly before this significant slice of our cultural and geospatial history was lost forever. An initial pilot was undertaken to test out the viability of a full scanning project for the whole archive, then the project itself, led by LINZ began.

The project began with three partner regions (Canterbury, Waikato and Bay of Plenty). Council partners continue to join the project progressively from across NZ as different areas became aware of the project and have funding to be able to join the initiative. It is estimated that the scanning of the Crown archive will be completed by 2021.

The photos were taken for a range of reasons such as land management and mapping. The value of these images is in showing change across New Zealand. Key drivers for having the images scanned broadly speaking are better decision making, complying with regulatory requirements and cultural heritage with specifics including using the images to support potential identification of “HAIL” contaminated land sites, accretion and recession of coastlines, changes in areas of significant vegetation and changes in river pathways.

 

Earthquakes continued…

Quakes have continued to rumble through the night in the north east of the South Island, with 28 recorded at Geonet in the last hour (4:20 to 5:20 am). There have been about 800 aftershocks altogether.

There are reports that there could be up to 100,000 landslides/slips.

Geonet says that multiple faults have ruptured:

Rapid field reconnaissance indicates that multiple faults have ruptured:

  • Kekerengu Fault at the coast – appears to have had up to 10m of slip
  • Newly identified fault at Waipapa Bay
  • Hope Fault – seaward segment – minor movement
  • Hundalee Fault 

What we are finding in New Zealand is that quite a few of our larger earthquakes involve jumping from rupture on one plane to another in a complex sequence.

‘Strong’ or ‘severe’ quakes overnight (these seem to have slowed down):

  • 5.0 (severe) 10:49:56 pm 10 km east of Kaikoura
  • 5.1 (strong) 12:16:42 am 15 km east of Seddon
  • 4.8 (strong) 1:03:00 am 5 km west of Kaikoura
  • 4.6 (strong) 4:22:19 am 10 km east of Seddon

So both Kaikoura and Seddon continuing to bear the brunt of this. Those are moderate sized quakes on the scale but they are shallow (8-25 km) so more energy gets to the surface than deeper quakes.

This map shows the pattern of quakes since midnight yesterday. Most of them are shallow.

earthquakes2016novdepthmap

Earthquakes midnight 14 Nov – 5:30 am 15 Nov (Geonet)

And this shows their strengths better:

earthquakes2016novstrength

Last 500 earthquakes light to severe as at 6:oo am 15 November 2016 (Geonet)

That shows the clustering in North Canterbury-Marlborough with a couple in Wellington but they feel the bigger Seddon quakes in Wellington too.

Updates from Geonet:

M7.5 Kaikoura Quake: What we know so far

Updated at 23.52, 14/11/2016 This earthquake was the largest recorded in New Zealand since the M7.8 Dusky Sound earthquake in 2009. But, given its location, it was more widely felt and more damaging. This earthquake unsettled many people and that is perfectly normal; earthquakes can be upsetting events. The best advice we have is to be prepared for earthquakes.  We can say one thing with certainty: there will be more earthquakes to come in this area.…

M7.5 Kaikoura Earthquake: Latest updates

Multiple ruptures

Rapid field reconnaissance indicates that multiple faults have ruptured:

  • Kekerengu Fault at the coast – appears to have had up to 10m of slip
  • Newly identified fault at Waipapa Bay
  • Hope Fault – seaward segment – minor movement
  • Hundalee Fault 

In the simplest case an earthquake is a rupture on a single fault plane.

What we are finding in New Zealand is that quite a few of our larger earthquakes involve jumping from rupture on one plane to another in a complex sequence. We first saw that with the Darfield Sept 2010 EQ where multiple segments ruptured together as a single earthquake. We appear to have seen this again overnight.

In terms of what might happen next: The scenarios provide an overview of how we see this earthquake sequence evolving over the next few days to one month. What is on the web page is our best information that we have to hand at the moment.

We’ve developed three scenarios based on what we know so far but be aware that our understanding is evolving as we do more analysis and receive more data. 

Scenario One: Very likely (80% and greater)
A normal aftershock sequence that is spread over the next few months to years. Felt aftershocks (e.g. M>5) would occur from the M7.5 epicentre near Culverden, right up along the Kaikoura coastline to Cape Campbell over the next few months to years. This is the most likely scenario.

Scenario Two: Likely (60% and greater)
In the next month, it would be likely that rupture of earthquakes of about an M6 in the North Canterbury and Marlborough regions will occur, as well as potentially offshore in Southern Cook Strait and offshore Kaikoura.

Scenario Three: Unlikely (less than 40%)
The least likely scenario is that in the next month, (it is unlikely but still possible) there would be rupture of longer known faults (with earthquakes of about M7), in the Marlborough and Cook Strait regions.

So there is at least likely to be a continuation of the many aftershocks, with the lower possibility of some quite large ones still to come.

Five years on and quakes continue

There was an awful reminder for Cantabrians last week that although a very damaging quake was five years ago it wasn’t a one off event and the after effects still dominate Christchurch.

There have been about 14,000 earthquakes in the area over that time, most centred in or close to Christchurch.

We felt the big ones in Dunedin and they were disconcerting enough but it’s easy to forget the impact on Canterbury from a distance.

Earthquakes and their aftermath are still a big deal. In many many cases nerves and finances are as frayed as the Earth’s crust seems to be.

The Press has a feature to mark this anniversary:

Five years, 14,000 quakes, and a new South Island

While Christchurch and Canterbury has been changed markedly, and a lot of renewal has been necessary, the rest of the South Island has only been affected in relatively minor ways.

The reality is that while I feel for those who have been impacted by the earthquakes, I really can’t know what it feels like for our close neighbours.

It’s easy to forget about the quakes from a distance, apart from occasional reminders like the bigger aftershocks and anniversaries.

The big two from Geonet:

  • M 6.3, Christchurch, 22 February 2011The city of Christchurch experienced a major earthquake centred south of the city; severe damage and casualties occurred.
  • M 7.1, Darfield (Canterbury), 4 September 2010The Darfield earthquake caused severe building damage in mid-Canterbury, particularly to the city of Christchurch. It revealed the existence of a hidden west-east fault under the gravels of the Canterbury Plains.

Five years ago, wow.