Very Strong shallow earthquake / aftershock near Seddon, South Island, New Zealand + Aftershock pattern

This is our main in-depth article from the very strong M6.5 earthquake in the Cook Strait where it all started
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Present AFTERSHOCK cycle

Update August 17 09:50 UTC :
5 people have been injured by the mainshock and the 2 very strong aftershocks
As what happened after the July 21 mainshock, also the August 16 mainshock will be followed by a vast number of sometimes very strong aftershocks. The aftershock pattern changes with every earthquake and New Zealand Cook Strait area has really bad luck. The main problem is that no-one can predict what the strength of the next one will be. Very strong ones (+M6) are certainly part of the possibilities. Big difference compared to the July mainshock is the epicenter location(s). They are now below land and thus a lot more dangerous than the July ones. Better for Wellington, indeed (greater distance), but a lot more dangerous for Seddon and Blenheim.
The 2 maps below are showing the aftershock pattern of yesterday and today.  The epicenters have shifted a little more to Seddon and Blenheim. Kaikoura seems to be holding its position away from the turbulence. Also to note is that today's aftershocks are with a few exceptions all below land.
Based on what we read on Twitter life goes on as before, even in Seddon and Blenheim.
All the aftershocks of August 17 can be seen on this page.
In-depth coverage of the misery in  all small details can best be viewed in the following websites :
Stuff.co.nz
TVNZ
Best earthquake data at Geonet (New Zealand) and at Earthquake-Report.com (mainly because we bring many sources and also the experience of some people who felt the earthquakes).

Main-shock and aftershocks for August 16 (whole UTC day)

Main-shock and aftershocks for August 17 (midnight UTC until 09:45 UTC)

Update 07:10 UTC : Nothing really new since our 06:08 update. The NZ press is mainly zooming in to small stories of the panic and the secondary effects like heavy traffic, experience reports of minor damage etc. All the aftershocks of M2.9 or greater will be listed below.

Update 06:08 UTC : One building south of Seddon nearly collapsed by the mainshock. Some others in Marlborough region were also severely damaged, while the damage on North Island (Wellington region) is only minor.

Update 06:01 UTC : GeoNet has changed the data to Magnitude 6.0. USGS and EMSC give Magnitude 5.9 (USGS expecting a heavy intensity again). The epicenter location is again close to Seddon, the quake was felt in many parts of New Zealand. New damage is likely.
In the meantime buildings in Seddon were ckcked for damage by the mainshock. Many of the buildings were damaged, mainly fallen chimneys and cracked walls and roofs are reported. No building collapsed, nobody was injured.

Update 05:38 UTC : Another very strong quake with Magnitude 6.3 hit this are a couple of minutes ago, according to GeoNet. These data are still prelimimary.

Update 05:28 UTC : Two injured people were carried to a hospital in Blenheim. There are not many details about the kind of injuries but reports indicate they are only minor.

Update 04:43 UTC : Taken into account the strong Magnitude and the extremely shallow Hypocenter,  we are happy that no injuries and even fatalities have been reported. Also the damage is within an acceptable range as no houses really collapsed. The slight to moderate damage will however be reported in big numbers. The most reports will come from Seddon, followed by Blenheim and then by Wellington.

Update 04:32 UTC : GNS Science has recalculated the data and is now reporting an updated value of M6.6 !

Update 04:32 UTC : NZ Media are starting to exaggerate : Monster Quake hit ... We can truly say that this was a big quake but not a monster quake. Based on security camera images we saw some moderate shaking in Wellington.

Update 04:25 UTC : The biggest damage should be looked at in the Seddon area. Gradually Seddon information and pictures are reaching us, like the one below from Seddon. Unsafe to live in, it will probably get a RED STICKER on the door from the NZQC after inspection.

Twitter image courtesy and copyright from @breakfastsam

Update 04:15 UTC : A house has been badly damaged in Ward, south of Seddon + some power lines down in the Seddon area

Update 04:06 UTC : SH 1 currently closed between Blenheim and Kaikoura. Check NZTA website for latest highway conditions:
http://t.co/d6e18GP2XW

Update 04:02 UTC : A number of people have been freed from lifts in the Wellington CBD which stopped when the quake struck.

Update 04:00 UTC : Earlier reports of a collapsed house in between Blenheim and Seddon looked to be incorrect. So far only a lot of slight damage in the Marlborough area (Seddon, Blenheim etc) and also in the Wellington area.

Typical picture after such an earthquake. A supermarket in Wellington !

Twitter image courtesy and copyright @LivLacey

Update 03:52 UTC : The NZ Stock Exchange has been reopened again

Update 03:46 UTC : Damage like the picture below will occur in many places. The NZ Earthquake Commission will have a lot of work the following days to follow up the many filed damage reports.

Twitter image courtesy and copyright @menabassily NZ

Update 03:44 UTC :  The NZ stock exchange has stopped trading. About 600 customers are reportedly without power in Makara, Wrights Hill and Wainuiomata following the quake

Update 03:44 UTC : The earthquake has been felt all over both islands. Power is still on the Wellington CBD (Central Business District) and traffic is flowing normally, however some power lines are reported to be down and there are problems with some phones.
Tranzmetro has suspended all its rail and bus services in Wellington and Wellington Airport advises the runway is temporarily closed for inspection following the quake.

Update 03:42 UTC : Focal Mechanism in line with the earlier Cook Strait M6.5 earthquake if based on USGS FM

Update 03:38 UTC : South of Blenheim, towards Seddon, roads are partially blocked by rockfalls and are cracked in some areas.

Update 03:34 UTC : Luckily only reports of what we call "minor damage" in the New Zealand press so far. Minor damage is like broken windows, cracks in walls, fallen tiles etc.

Update 03:31 UTC : What strikes us in the New Zealand press is that all of them are talking about a "Wellington" earthquake and not about a Seddon earthquake . The distance to Wellington is far greater than to Seddon.

Update 03:27 UTC : We expect most damage in the whole North Eastern part of the South Island with some slight damage even at the south of the North Island. Seddon, only located at 10 km of the epicenter is most at risk for damage followed by Blenheim.

Update 03:22 UTC : Based on what we experienced with the M6.5 mainshock a little while ago a chain of aftershocks in the same area may be expected.

Update 03:20 UTC : A lot of different data below like USGS who reports a M6.8 at a depth of 10.6 km. We prefer however tu use the Geonet / GNS science data who are reporting M6.2 at a depth of 8 km. Even more a difference in epicenter location. The preliminary USGS value is putting the epicenter more below land vs the Geonet versions who is locating the epicenter also below land but close to the coast.

Update 03:18 UTC : these aftershocks will go on for quiet some time ane very strong ones are being possible.

Update : The seismogram below reveals a long chain of powerful aftershocks, some of them more than M5.

Very dangerous aftershock below land in New Zealand. Epicenter is very different with each reporting agency. Geonet New Zealand is locating the epicenter at the land-tip of the South Island. The earlier mainshock and most of the aftershocks were located in the sea.

Image courtesy Geonet New Zealand

10 km south-east of Seddon

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