7.6 Earthquake. South Pacific Just North of NZ

Earthquake Details

This event has been reviewed by a seismologist.

Magnitude 7.6
Date-Time

Friday, October 21, 2011 at 17:57:17 UTC
Saturday, October 22, 2011 at 05:57:17 AM at epicenter

Location 28.941°S, 176.046°W
Depth 39.8 km (24.7 miles)
Region KERMADEC ISLANDS REGION
Distances

180 km (112 miles) E (79°) from Raoul Island, Kermadec Islands
870 km (541 miles) S (185°) from NUKU'ALOFA, Tonga
2978 km (1851 miles) WSW (240°) from PAPEETE, Tahiti, French Polynesia

Location Uncertainty horizontal +/- 15.7 km (9.8 miles); depth +/- 10.8 km (6.7 miles)
Parameters NST= 94, Nph= 94, Dmin=187 km, Rmss=2.44 sec, Gp= 50°,
M-type=regional moment magnitude (Mw), Version=5
Source

Magnitude: USGS NEIC (WDCS-D)
Location: USGS NEIC (WDCS-D)

Event ID usb0006b6p

earthquake.usgs.gov...

This is on the ocean spreading rift and continental boundary rift and subduction zones just south of Tonga and a little North of New Zealand.

Thanks for the update.

Appears this occurred 15minutes or so ago...

If there were a tsunami I would 'hope' that we would have a warning by now of it.

Hmmm, 24 miles depth. That should absorb most of the shock I would think.

Located in a highly seismically active region as well.

I would have to say this should be expected by anyone who lives in the surrounding island chains, historically speaking at least.

My initial estimates would be that damage will be limited. I don't know we will have to wait and see.

reply to post by muzzleflash

yeah...looks like they aren't expecting a widespread tsunami. The location of this is right on the Continental rift boundary.

EVALUATION

NO DESTRUCTIVE WIDESPREAD TSUNAMI THREAT EXISTS BASED ON
HISTORICAL EARTHQUAKE AND TSUNAMI DATA.

HOWEVER - EARTHQUAKES OF THIS SIZE SOMETIMES GENERATE LOCAL
TSUNAMIS THAT CAN BE DESTRUCTIVE ALONG COASTS LOCATED WITHIN
A HUNDRED KILOMETERS OF THE EARTHQUAKE EPICENTER. AUTHORITIES
IN THE REGION OF THE EPICENTER SHOULD BE AWARE OF THIS
POSSIBILITY AND TAKE APPROPRIATE ACTION.

THIS WILL BE THE ONLY BULLETIN ISSUED FOR THIS EVENT UNLESS
ADDITIONAL INFORMATION BECOMES AVAILABLE.

ptwc.weather.gov...

earthquake-report.com...

New Zealands Geological Service GNS has it at 7.3
www.geonet.org.nz...

if its a 7.6 thats 378,7985.6 tonnes of TNT
if its a 7.3 thats 134,4028.0 tonnes of TNT
released
thats a big difference

I'd tend to believe the Kiwis, closer to the event

Well this was expected...

The last ``big`` earthquake was on September 19. Another big one was due.

Stay safe in the Pacific!

[sarc] Good thing this is all just "normal"
and there is nothing to worry about.

Earth changes?
What earth changes? [/sarc]

OK...this has been downgraded to a 7.4 officially by the USGS.

The most recent assessment of this from them is that this is quite possibly an aftershock from the 7.6 quake that occurred in early July 2011.

July 6 quake link
USGS link for July quake

In July of this year, a M 7.6 event occurred approximately 45 km to the south-southwest of the October 21 earthquake, breaking a normal fault within the subducting Pacific plate also very close to the Kermadec Trench. This event was notable because it triggered a large number of thrust-faulting aftershocks to the west of the plate boundary, on or close to the interface between the Pacific and Australian plates. The October 21 earthquake may be related to that aftershock sequence.

Source

The July quake here triggered tsunami warnings in the area including into NZ. One was detected, but did little damage to anything around. This one apparently didn't trigger a tsunami.

According to the USGS, the Pacific plate here is moving westward under the Australian plate at a rate of 61mm/year. The July quake apparently was a normal fault and occurred just west of the Kermadec Trench with the down-going slab..or Pacific Plate.

Today's quake was a reverse fault and occurred just to the east of the subduction zone. The aftershocks in July were west of the area, this one is east. It is suspected this is an aftershock of that one since it appears the Pacific plate actually rose up some like it was relieving stress from earlier...just in a slightly different place. Thus lengthening the distance between the areas slightly.

A good written and picture explanation of what I just tried to say is here: Reverse Fault explanation

reply to post by muzzleflash


A tsunami warning was issued for NZ, but has now been cancelled.
Could have made the Rena oilspill clean-up interesting

All our local warnings from Civil Defence cancelled now too.

Massive trace on our Geonet drums:

www.geonet.org.nz...

What the heck is that USGS only posts 1 of the 2

reply to post by webpirate


I've looked around for ocean spreading rifts but could not zero in on any that clearly showed the layout of the south Pacific in that way. Do you know of any good links that would illustrate them?

OMG Harold Camping was right... woe woe woe... THE END! THE END! THE END!

LMAO

reply to post by webpirate


Isaw that today I have a phone app watching the quakes, did you notice the 4.6 in southern texas yesterday? i been around here for 13 years first one i ever felt or heard of in this area. I did a research and found that the Balcones fault line is under me, ya me. also central calif has had a few 4; and highers lately, i feel a biggy comming

Originally posted by aboutface
reply to post by webpirate

 

I've looked around for ocean spreading rifts but could not zero in on any that clearly showed the layout of the south Pacific in that way. Do you know of any good links that would illustrate them?

The

hisz.rsoe.hu...

map shows the plate boundaries as well as the subduction zones. Anywhere these are located close to each other like we see where the quake today was I think there is the potential for spreading. They also have areas that do show the spreading. Mostly those are the green zones. There's a big one out in the middle of the Atlantic too.

If you look closely at the ocean floors on that map you can actually see the larger areas of spreading yourself.

reply to post by webpirate


Any one herd anything else on this

reply to post by Vitchilo


The Christchurch EQ happened on Sept 3, 2010.

There was another 'big' one in that region closer to the date. Here. On Sept 15, 2011. Exactly 188-189 days from Japan EQ which was exactly 188-189 days from the New Zealand Quake. The EQ in Mid Sept 2011 was exactly 0.2 points higher than the NZ quake, 376-377 days before. Funny, the Japan to Chile quake difference was also 0.2 points and also 376 days previous.

Wonder what may happen 22-23 March, 2012?

Originally posted by LightAssassin
reply to post by Vitchilo

 

The Christchurch EQ happened on Sept 3, 2010.

There was another 'big' one in that region closer to the date. Here. On Sept 15, 2011. Exactly 188-189 days from Japan EQ which was exactly 188-189 days from the New Zealand Quake. The EQ in Mid Sept 2011 was exactly 0.2 points higher than the NZ quake, 376-377 days before. Funny, the Japan to Chile quake difference was also 0.2 points and also 376 days previous.

Wonder what may happen 22-23 March, 2012?

For that "188-189" situation you find answer for that possible theory here ..

You find too what I think for dangerous dates in 2012 ..

www.abovetopsecret.com...

Peace ..

For anyone who predicted a big
quake today - this is it. Thank
goodness it was out in the Pacific
and not on land.