M 7.8 OFF WEST COAST OF THE SOUTH ISLAND, N.Z.

[highace]

heres a report from geonet 3:30pm today NZST
http://www.geonet.org.nz/news/article-jul-16-2009-fiordland-quake-biggest-for-80-years.html

I also notice on the USGS phase data page at the top they list the various types of magnitudes

GS= 7.6 ,  mb = 6.6 ( 45),   ML = 6.6 (  2)  mblg = 5.8 (  6)

So geonet was right at the very start ........... 6.6ML.

[highace]

Heres the preliminary aftershock list off the NZ Earthquake Catalouge after 21 hours

 REF, LAT, LONG, TIME, DEPTH, MAG
3124785, -45.76239, 166.56255, 2009/07/15 09:22:29.0, 12, 7.256
3124792, -46.03566, 165.93748, 2009/07/15 09:41:53.8, 12, 6.131
3124795, -46.19619, 165.79095, 2009/07/15 09:52:16.5, 13, 5.571
3124798, -45.76283, 166.4595, 2009/07/15 10:01:49.7, 5, 5.57
3124807, -46.17328, 166.00424, 2009/07/15 10:21:33.8, 19, 5.075
3124810, -45.5897, 166.74782, 2009/07/15 10:32:46.4, 12, 4.759
3124816, -45.95671, 166.51808, 2009/07/15 10:51:34.0, 12, 4.427
3124826, -45.47593, 166.82671, 2009/07/15 11:21:55.6, 13, 4.761
3124828, -46.15899, 166.98158, 2009/07/15 11:31:29.7, 12, 4.786
3124831, -45.43784, 166.51775, 2009/07/15 11:44:13.6, 12, 5.174
3124834, -45.8948, 167.00197, 2009/07/15 11:49:42.0, 5, 4.9
3124841, -45.5377, 166.6243, 2009/07/15 12:09:25.1, 4, 4.703
3124853, -45.96168, 167.04495, 2009/07/15 12:48:38.9, 5, 3.913
3124859, -46.00945, 166.26184, 2009/07/15 13:08:42.9, 19, 3.678
3124863, -45.47298, 166.59122, 2009/07/15 13:27:48.1, 5, 4.168
3124866, -45.8502, 165.68784, 2009/07/15 13:35:55.3, 5, 4.952
3124868, -45.4562, 166.8802, 2009/07/15 13:42:48.1, 5, 4.396
3124869, -45.40466, 166.49757, 2009/07/15 13:50:38.1, 5, 5.943
3124871, -45.45972, 166.62106, 2009/07/15 13:50:39.6, 5, 5.436
3124878, -46.2777, 166.267, 2009/07/15 14:15:27.6, 177, 5.156
3124894, -45.57555, 166.58679, 2009/07/15 15:07:39.3, 12, 4.062
3124898, -45.49235, 165.76328, 2009/07/15 15:16:22.1, 33, 4.389
3124900, -46.18413, 166.03903, 2009/07/15 15:29:35.3, 24, 4.234
3124905, -46.01685, 165.983, 2009/07/15 15:37:52.2, 12, 3.823
3124918, -45.4622, 166.63675, 2009/07/15 16:17:29.9, 5, 4.612
3125113, -45.53423, 166.57462, 2009/07/15 16:19:26.4, 12, 4.881
3124929, -45.80865, 166.31857, 2009/07/15 16:51:21.0, 12, 4.67
3124930, -45.58012, 166.69141, 2009/07/15 16:55:15.2, 12, 4.545
3124934, -45.45794, 166.30945, 2009/07/15 17:12:10.1, 5, 3.987
3124976, -45.80267, 166.62463, 2009/07/15 19:27:51.8, 5, 4.556
3124983, -46.18603, 166.86388, 2009/07/15 19:44:28.1, 12, 4.235
3124997, -45.45035, 166.64084, 2009/07/15 20:22:20.1, 5, 4.827
3125006, -46.22971, 165.90424, 2009/07/15 20:45:24.4, 12, 4.817
3125010, -45.85984, 166.24135, 2009/07/15 20:59:27.1, 5, 4.544
3125012, -46.0363, 166.08708, 2009/07/15 21:08:54.5, 12, 3.886
3125018, -46.07504, 166.0148, 2009/07/15 21:28:33.0, 13, 3.436
3125022, -46.53273, 165.95502, 2009/07/15 21:36:01.0, 12, 5.38
3125050, -46.18268, 166.07726, 2009/07/15 22:57:56.3, 22, 4.261
3125055, -45.62372, 166.64114, 2009/07/15 23:14:26.8, 12, 4.746
3125061, -45.52136, 167.03345, 2009/07/15 23:41:20.7, 65, 5.077
3125068, -46.38105, 166.15764, 2009/07/16 00:00:10.8, 5, 4.364
3125075, -45.64015, 166.53464, 2009/07/16 00:19:10.2, 12, 4.346
3125077, -46.1981, 166.16083, 2009/07/16 00:24:07.0, 5, 5.333
3125082, -46.19046, 165.88213, 2009/07/16 00:39:11.6, 12, 5.001
3125083, -46.2877, 165.86664, 2009/07/16 00:44:46.5, 5, 5.55
3125086, -46.22295, 166.07552, 2009/07/16 00:54:13.0, 12, 4.03
3125087, -45.97225, 166.27116, 2009/07/16 00:57:19.6, 17, 3.539
3125088, -46.31156, 166.05446, 2009/07/16 01:01:29.7, 12, 4.295
3125089, -45.64417, 166.6673, 2009/07/16 01:05:19.7, 5, 3.34
3125111, -45.77022, 166.54375, 2009/07/16 02:07:33.1, 5, 4.861
3125112, -45.40023, 166.74998, 2009/07/16 02:13:09.9, 12, 5.139
3125133, -46.37025, 165.61317, 2009/07/16 03:19:08.5, 12, 4.988

map of the above



TV News has some video footage, locals saying there have been hundreds of aftershocks, not just the 53 listed, will take about a week to table them all.
http://tvnz.co.nz/national-news/officials-survey-quake-damage-2849974/video

Good night all, its been a long day, been up since 3:30am

[Auntie]

A series of small tsunamis have hit the NSW coast in Australia.  Small tsunamis followed by unusual current movements at Port Kembla at 10.06pm and also at Spring Bay, southern Tasmania, at 10.05pm.

A Bureau of Meteorology said it is likely there will be more waves and unusual currents early today.

The State Emergency Service in Wollongong received 250 calls from worried residents. A Kiama caravan park was evacuated as well as boat-dwellers at Bermagui Harbour.


SES officers were sent to Kiama Harbour and observed water levels receding by about 40cm before surging in again, while at Port Kembla the water receded by about 20cm.

Coastguards, police and fire services were all put on red alert as the danger to low-lying and coastal areas was assessed.

Under-sea quakes in the New Zealand region are the most dangerous kind for generating tsunamis that could affect the Australian coastline. Professor Bryant of Wollongong University has stated several times that New South Wales is well overdue for a major tsunami.

 In Sydney, a performance at Bondi Pavilion was cancelled and the theatregoers were evacuated, while other Sydney residents were warned to keep away from the water's edge.

About 50 people were also evacuated from homes and resorts on Lord Howe Island (an Island off the New South Wales coast)

Tourists and residents were relocated from low lying areas to the old Met site on higher ground for about three hours on Wednesday night, a representative from the Arajilla Retreat resort said.

"We were in our cars for two or three hours," the representative, who did not wish to be named, told AAP.

"There were 40 or 50 of us maybe, but a lot of people live up the top of the island anyway."

 Most of the island's residential and tourist accommodation was on high ground, she said.

[highace]

Auntie, I read in this mornings newspaper that the Lord Howe Islanders were a bit peturbed about having to evacuate for a 20cm wave .............. blaming Hawaii for getting it all wrong. The initial magnitude was 6.6 not 8.1, I think they (Tsunami Centre) panicked.

Interesting about Kiama harbour.

another strong aftershock last night
REF, LAT, LONG, TIME, DEPTH, MAG
3125201, -45.8236, 166.3652, 2009,/07/16  06:30:1.4, 128, 6.228

Its not on the Recent Quakes on geonet, probably because of the depth, and it wouldn't have been felt.

[Sunnygal]

Do you remember the story that came out a few mos. ago about Hawaii's Tsunami warning center having had some faulty equiipment? I put the story here somewhere, heckifi know where, lol. I THINK....the story reported that they had/have now gotten some improved stuff but maybe not and from what you say, they sure didn't upgrade well enough.

I keep seeing the magnitude of that thing as 7.6.

Are you saying that closer to the thing folks are claiming it was a lot smaller??

[highace]

sunnygal, the local l magnitude of the quake was 7.256ML but the NZ geonet people are taking on board the USGS advise from a distance that it was bigger ... a 7.6
The various types of magnitude are
(1) local magnitude (ML), commonly referred to as "Richter magnitude,"
(2) surface-wave magnitude (Ms),
(3) body-wave magnitude (Mb),
(4) moment magnitude (Mw)

USGS have the main quake as follows;
 
mb= 6.6 ( 45), 
ML = 6.6 (  2) 
mblg = 5.8 (  6)
GS= 7.6

I have no idea what GS is,

perhaps Don in Hollister or JOB can explain.

this is the page with all the figures.
http://neic.usgs.gov/neis/eq_depot/2009/eq_090715_jcap/neic_jcap_p.html

[Sunnygal]

Ahh, okay thanks Highace.

Are you hearing anyone there saying they expect more? Any oddities being reported? any beachings, etc?

[highace]

no one knows what will be next sunnygal, but this quake is a classic type for this part of NZ, and they usually just peter out till the next big one
This part of the West Coast is known as Fiordland.
heres the list, I've only got back as far as 1960 so far, over 6 mag.
2009 - 7.3 +6.0 +   6.3
2008 - 6.0
2007 - 6.7 + 6.2
2004 - 7.1 ( a little bit further south)
2000 - 6.2
1996 - 6.2
1993 - 6.8
1989 - 6.1
1988 - 6.1
1979 - 6.5
1976 - 6.6
1965 - 6.5
1960 -6.3

you can see them on my yearly historical blog "tauhouanga", I don't post the actual lists, there is just too much information, especially those ones with thousands of aftershocks.

http://tauhouanga.blogspot.com/


what the locals are worried about is what if theis large quake breaks the clamp on the Alpine Fault? its been  locked for nearly 15 years now without a major quake, just 2 fives in that whole time, they are worried because Christchurch, NZ's 2nd biggest city is only 50 or so km from it.

[highace]

I won't waste space here on JOB's forum listing all the aftershocks, if anyone is interested I've started a page on my 2009 Blog just to follow the aftershocks

http://seabreeze.wordpress.com/2009/07/15/15-07-2009-fiordlandsw-coast/

I'll keep updating it every 12 hours from now on, they are dropping off to 3s and 4's now as expected after 48 hours.

[highace]

This from Geonet;
"The mainshock was a large reverse faulting or thrust mechanism resulting from the Australian plate pushing (subducting) beneath the Pacific plate upon which Fiordland lies. This is the largest and one of very few examples of this type of earthquake in New Zealand, making it very important for our understanding of hazards here. The aftershocks are concentrated at either end of the faulting area and are mainly a mixture of reverse faulting and strike-slip faulting mechanisms reflecting the complexity of the tectonics in the area.

The earthquake rupture started at about 30 km depth and ruptured upwards and to the south, focusing energy offshore. The motion was more like a lurch than a snap (meaning the energy was released more slowly); this is typical for a subduction thrust event. This explains why the damage was much less than many people expected for this size of earthquake. The motion was slower (with lower frequency shaking) and "rolling" rather than the sharp (higher frequency shaking) movements that cause building damage; this also explains the low number of landslides.

This, and the remoteness of the epicentre, means that New Zealand has been very fortunate - if this earthquake had happened anywhere else it would have caused huge damage, even with the mitigating low frequency behaviour.

he deformation caused by the Dusky Sound earthquake resulted in the movement of the south-west of the South Island towards the west-south-west (in a direction somewhat to the south of Australia). The map to the right shows the horizontal motion of various points in south-west New Zealand. The blue arrows are observed permanent displacements due to the earthquake (there are only four of these on the map). The largest is about 350 mm of motion at Puysegur Point in south-west Fiordland (see below for how to observe the data); the red arrows are predicted displacements at other points.

Large earthquake occurrence in New Zealand has shown clustering in time (mid-1800s and late 1920s to early 1940s). Therefore, in general, the probability of an event is higher after a large earthquake than before. The occurrence of the Dusky Sound earthquake does not mean we have had the "big one" as more are always possible. It is also important to remember that large earthquakes can occur in many parts of New Zealand, not just Fiordland.

The stress on the southernmost (offshore) section of the Alpine Fault was increased by the Dusky Sound earthquake. We do not know how close the offshore segment of the Alpine Fault is to rupturing, so the effect of this earthquake is uncertain. If the offshore section of the Alpine Fault was to rupture, it is unlikely to rupture into the onshore section. The known geology of the Alpine Fault does not indicate that earthquakes on this fault have been closely clustered in time.

A detailed study using a model of the fault system and earthquake occurrence is required if we are to get a better understanding of the probability of a southern Alpine Fault earthquake being caused by the Dusky Sound earthquake; such a study would take many months.



Link showing larger map

http://www.geonet.org.nz/images/news/2009/Fiord_model1.png




http://www.geonet.org.nz/news/article-jul-16-2009-fiordland-quake-biggest-for-80-years.html

[highace]

As of 31st october 2009 this quake has been revised by Geonet to 7.247ML (changed from original 7.22ML then 7.256ML)

[highace]

Over the wet weekend I'll be updating the Dusky Sound page on my blog, I only followed the aftershocks for the first 19 days, a lot of the magnitudes have been altered after review by GNS scientists.
Heres the latest overall data up to mid day 1st Oct 2009 NZDT plotted by location and magnitude