NZ earthquake 14.11.16 - Mag 7.8

  • #1
fresh_42
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I know we have members who watch earthquakes and especially in that region.

http://www.bbc.com/news/world-asia-37967178
Potsdam and CNN even report 7.8 in 10 km depth. Tsunami warning set.
Does anybody know more?
 
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  • #3
Borg
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Sure the link has been meant?
Oops. Fixed it.
 
  • #4
StevieTNZ
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apologies for the sloppy writing

http://www.stuff.co.nz/national/86416304/live-north-canterbury-quake

"A severe earthquake measuring 7.5 magnitude has hit in North Canterbury, near Hanmer Springs.

It was widely felt in both the South and North Islands, as far north as Auckland, causing damage and knocking out power."

I felt it all the way in Wellington. The house shook so much I thought the earthquake was based in Wellington. A few things fell down. Also, lots of aftershocks, some rather big, some small but still noticeable.

Then the tsunami sirens went off so I had to get out of bed and gather a few items. Currently we are all further inland. I believe the sirens have now stopped, but we'll wait a bit more.

I cannot imagine the damage in Christchurch again.
 
  • #5
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https://www.physicsforums.com/threads/7-4-earthquake-usgs-in-nz.893195/#post-5619024 [Broken]

Edit: @davenn
 
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  • #7
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A minor tsunami did occur in NZ but isn't expected to impact anything beyond the island.
RECOMMENDED ACTIONS
-------------------

* NEW ZEALAND CIVIL DEFENSE HAS ISSUED A TSUNAMI THREAT
MESSAGE FOR THE EAST COAST OF SOUTH ISLAND.

* TSUNAMI THREAT BEYOND NEW ZEALAND IS NOT EXPECTED.

TSUNAMI OBSERVATIONS
--------------------

* THE FOLLOWING ARE TSUNAMI WAVE OBSERVATIONS FROM COASTAL
AND/OR DEEP-OCEAN SEA LEVEL GAUGES AT THE INDICATED
LOCATIONS. THE MAXIMUM TSUNAMI HEIGHT IS MEASURED WITH
RESPECT TO THE NORMAL TIDE LEVEL.

GAUGE TIME OF MAXIMUM WAVE
COORDINATES MEASURE TSUNAMI PERIOD
GAUGE LOCATION LAT LON (UTC) HEIGHT (MIN)
-------------------------------------------------------------
CASTLEPOINT NZ 40.9S 176.2E 1210 0.12M/ 0.4FT 18
WELLINGTON NZ 41.3S 174.8E 1232 0.43M/ 1.4FT 16
KAIKOURA NZ 42.4S 173.7E 1140 1.47M/ 4.8FT 16
 
  • #8
fresh_42
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As to why there are varying figures on the scale (USGS changed from 7.4 to now 7.9, Potsdam had 7. 8 and I've heard 6.6 by local reports):
A geology professor on a news channel here said: "It's difficult to determine the exact magnitude because it lasted so long, more than 2 minutes." Aftershocks are still occurring, but the danger of a major tsunami is likely banned.
 
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  • #9
Astronuc
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Here's the USGS info:
http://earthquake.usgs.gov/earthquakes/eventpage/us1000778i#executive

They are also reporting 7.8.
NZ Geonet reports Mag 7.5 at 15 km depth, 15 km north-east of Culverden, which is about 53 km NNE of Amberley
https://www.geonet.org.nz/quakes/region/newzealand/2016p858000

There are several large quakes toward Kaikoura reported by USGS.

Mag 6.5 - http://earthquake.usgs.gov/earthquakes/eventpage/us10007795#executive,
https://www.geonet.org.nz/quakes/region/newzealand/2016p858055

Mag 6.2 - http://earthquake.usgs.gov/earthquakes/eventpage/us100077aj#executive,
https://www.geonet.org.nz/quakes/region/newzealand/2016p858279

and a few more in the 5 to 6 Mag range.
 
  • #10
StevieTNZ
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It was so scary, I was nearly in tears while we drove inland thinking our home could be gone. You hear about this happening overseas, but you really know what it feels like when you're faced with that situation.

A lot of schools and business' will be closed in Wellington and Christchurch. The trouble is NCEA end of year exams are happening.
"NZQA are yet to issue a statement on exams but they have talked to RNZ. A spokeswoman said most schools around the country should be open for business, but others in the quake and tsunami zones may not be. It may be the case at some schools that their practice exam results are used in place of exams, using the standard "derived grades" process."

So far, two people are confirmed dead.
 
  • #11
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Two nice videos on New Zealand tectonics


Pushing New Zealand's Boundaries

followed by:
New Zealand: where two tectonic plates collide
 
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  • #12
davenn
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As to why there are varying figures on the scale (USGS changed from 7.4 to now 7.9, Potsdam had 7. 8 and I've heard 6.6 by local reports):
A geology professor on a news channel here said: "It's difficult to determine the exact magnitude because it lasted so long, more than 2 minutes." Aftershocks are still occurring, but the danger of a major tsunami is likely banned.

Yes, the initial report from GNS ( in NZ) was 6.6, it was horribly under estimated ... my system was in overload for some 40 minutes and when the USGS report of 7.5 came out I knew that would be much closer to reality.
The really interesting thing about this event and the subsequent ones is that they are very widespread but in a line from the original M7+ and trending NE'wards
The whole area fired up. I have seen this several times over the years around the world but not like this in New Zealand.
And interestingly, almost all of the larger following events were not even in the area of the main shock.

So far 2 people have been reported killed, one when their house collapsed on them :frown:


Dave
 
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  • #14
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So happy you and your family are ok Stevie.
 
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  • #16
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I've been watching davenn's observation of the NE trend to the "aftershocks" and they are, indeed, unusual. Until the latest one, a 6.8 near the first quake, they (the later quakes) are moving closer to Wellington. It looks like they are along the offshore projections of the Wellington and Wairarapa faults on the other island. Very interesting and unnerving if I lived in Wellington.
 
  • #17
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Kaikoura_Blenheim_earthquakes-nz.png

I took a screen shot of the USGS page of recent earthquakes.

The Mag 7.8 is the blue dot, and the second Mag 6.5 is the red dot. North of Kaikoura, straddling the fault are a Mag 6.5, 6.2 and 6.1 earthquakes. To the northeast is a cluster of Mag 5s near Ward, NZ, Lake Grassmere and Cape Campbell.

Seismotectonics of the Eastern Margin of the Australia Plate
http://earthquake.usgs.gov/earthquakes/eventpage/us100077hw#region-info
 
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  • #18
StevieTNZ
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  • #19
davenn
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This is interesting:


EDIT: also, I think the largest aftershock so far has been 6.2 in the Nelson region. That hit at 1.34pm.
http://www.stuff.co.nz/nelson-mail/...learning-centres-closed-for-earthquake-checks


ohhh man, you just got to love inaccurate media reporting :rolleyes: . None of the events have been anywhere near Nelson City,
let alone Nelson Province

But the comment from GNS about it being a double event, is a possibility, it does happen periodically
I'm going to be really interested to see if any visual ground surveys of the region of the main event shows any surface faulting
It may not happen because of the depth.


Dave
 
  • #20
Astronuc
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Another site for information and interesting maps showing faults.
http://www.canterburyquakelive.co.nz/

http://www.canterburyquakelive.co.nz/Browse/?Index=106
They have the big one at 7.53 Mag, or equivalent to 30 Mt.

Nelson to Kaikoura is about 130 km (80.7 miles). Is it possible Nelson received some P-waves? Possibly from the Mag 6+ group that were 12 to 23 km N to NNW from Kaikoura toward Blenheim?

A number of years ago, I was about 60 miles from a Mag 6.5, and I felt the P-wave then S-wave. I was sitting on a large couch, and all of a sudden, it started shaking like an imbalanced washing machine. Moments latter, it started bouncing.
 
  • #21
StevieTNZ
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This is an interesting video to watch, showing the earthquakes and where they occurred.
https://nz.news.yahoo.com/video/watch/33201729/watch-a-days-worth-of-earthquake-data-as-massive-7-5m-hits-new-zealand/#page1
 
  • #22
davenn
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Nelson to Kaikoura is about 130 km (80.7 miles). Is it possible Nelson received some P-waves? Possibly from the Mag 6+ group that were 12 to 23 km N to NNW from Kaikoura toward Blenheim?

ohhh yes, indeed the larger events the high 5's, 6's and the 7.5 would have all been felt in Nelson City area starting with the quick pulse of the P followed by the S and surface waves 10 - 15 sec later.

A number of years ago, I was about 60 miles from a Mag 6.5, and I felt the P-wave then S-wave. I was sitting on a large couch, and all of a sudden, it started shaking like an imbalanced washing machine. Moments latter, it started bouncing.


it's a freaky feeling huh.
 
  • #23
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Talk about ripping up the ground! 7.8 Magnitude Quake in New Zealand Leaves Cows Stranded on Small Island of Grass

https://www.yahoo.com/gma/video/7-8-magnitude-quake-zealand-084403999.html
 
  • #24
jtbell
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  • #25
StevieTNZ
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Yeah, saw that on the news. Poor animals. :(

Went to bed rather early last night, around 7pm. While I was trying to get asleep two aftershocks occurred. Both were located east of Wellington. The 2nd one was more violent than the first, and I thought that again things would fall down and the sirens would go off.
 
  • #26
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Somewhat of a sum up:
1. There have been more than 800 quakes since Monday's M7.5 quake in North Canterbury - which was two quakes together.
2. It's likely that smaller aftershocks will continue, but there is close to a 40% chance of another large shake soon.
3. Two people were killed in the quake, in Kaikoura and Mt Lyford.

and 4. Wellington is being hammered with heavy rain and winds. The Hutt River is, unconfirmed at the moment, "bursting its banks with all this rain."
 
  • #27
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I woke just after midnight to my house falling apart again. There was slow rolling with no high frequency component which lasted for 2mins. It was different from the violent jolting of our Christchurch quakes of 5 years ago and I realized the quake was not local and some poor blighters were really in trouble. My first thought was that it was the Alpine fault as we expect this kind of quake from that fault. Luckily it was at night or casualties could have been a lot higher.
 
  • #28
StevieTNZ
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I woke just after midnight to my house falling apart again.
Where are you based?
 
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  • #32
StevieTNZ
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I woke just after midnight to my house falling apart again. There was slow rolling with no high frequency component which lasted for 2mins. It was different from the violent jolting of our Christchurch quakes of 5 years ago and I realized the quake was not local and some poor blighters were really in trouble. My first thought was that it was the Alpine fault as we expect this kind of quake from that fault. Luckily it was at night or casualties could have been a lot higher.
When I woke up because of the quake (I'm in Lower Hutt), I thought it would stop. But it got more intense and once I heard things falling down in other rooms, I thought 'this isn't good'. I expected that the quake was located quite near Wellington. It did go through my mind that the house could collapse, once I heard things falling. I -cannot- imagine what it was like down in Christchurch 2010 and 2011.
 
  • #33
StevieTNZ
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This is scary: http://www.stuff.co.nz/national/86497605/Concerns-over-building-stability-in-central-Wellington

Police have cordoned off an area of central Wellington over fears a large building is structurally unsafe.

Emergency Services rushed to Molesworth St, near Parliament, where the road has been blocked off.

And the building which houses staff for Statistics NZ is declared unsafe, and it may be a year before they could re-enter. Little detail has been shared about how it is inside, they believe some concrete beams have fallen.
 
  • #34
davenn
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My first thought was that it was the Alpine fault as we expect this kind of quake from that fault.

When the Alpine Fault unzips it will be a M8 + ... going on historical data that research unveiled about offset amounts etc ( remembering the last event was pre European settlement) It would be safe to estimate a M8.5 or so. Something in the order of ~ 10 times the amplitude of this latest event and there won't be anyone anywhere in NZ that won't feel it.

It's really interesting to note all the major events over the last 150 - 200 yrs have been have been to the south and north of the main central section of the AF.
I haven't seen any recent stress field data for the central section, it must be quite significant.

Dave
 
  • #35
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I was just shown a plot of the LHC beam excursion during the event. Of course the beam didn't shake - it was the reference point attached t the earth.
 

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