Why no Tsunami for this quake?

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posted on Jan, 2 2005 @ 11:38 PM
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23-DEC-2004 14:59:04 -50.24 160.13 7.8 10.0 NORTH OF MACQUARIE ISLAND

On dec 23, there was a 7.8 quake near Australia and New Zealand. Its great nothing happened, but why didnt a 7.8 cause a tsunami for Tasmania and New Zealand?




posted on Jan, 3 2005 @ 12:34 AM
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After that there was an 8.1 earthquake in that area about a day or two after, some believe those earthquakes were precursors to what happened next in SE Asia.

[edit on 3-1-2005 by Muaddib]



posted on Jan, 3 2005 @ 03:24 AM
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The reason a 7.8 or an 8.1 don't do much, is because a 9.0 is something like 32 times more powerful. The aftershocks are in the 5.0-7.0 range and haven't been doing much damage, and haven't been causing any new tsunamis, although the sea is choppier and storms are prevalent in the area this time of year anyway. My fear, is that the 9.0 was an underwater volcanic eruption that might reoccur. That could explain the highly localized series of strong quakes. I mean, a trench 1000m long, 30m wide opened in the sea floor, more accurately exploded. That's no small event. It was an unusual circumstance which I hope will not be soon repeated. If only for the sake of those brave, lucky individuals who have survived up until now without airlifts, medical aid, or help of any kind.



posted on Jan, 3 2005 @ 04:05 AM
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From my understanding with this particular quake in the Southern Ocean is that the plates moved horizontal and not vertical as with the Indonesian Quake.
Therefore not causing the huge displacement of water upwards which would cause a Tidal Wave.
Any other theories to why not?



posted on Jan, 3 2005 @ 07:35 AM
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The plates on the ocean floor have to be displaced for one to become a Tsunami.



posted on Jan, 3 2005 @ 09:15 AM
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Spitting Cobra says:

"The plates on the ocean floor have to be displaced for one to become a Tsunami."

Not necessarily. Any displacement can generate a seismic sea wave (tsunami); although a tectonic shift is the usual culprit, an underwater landslide (or even an above-water one that dumps a bunch of land into the sea) can start a tsunami.

That's the big fear about a tsunami striking the United States' East Coast; a seamount collapse near, say, the Azores could (not necessarily would) generate a large tsunami indeed, and devastate the East Coast cities of both North and South America.

As an aside, that's probably the only tsunami danger the East Coast folks have, since the only Atlantic tectonic boundary of note is a divergent one, not a transform or subducting one.



posted on Jan, 3 2005 @ 09:27 AM
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Sorry, your right a Landslide can also cause the Tsunami.

The question was, Why didnt this earthquake cause one.



The case you are talking about would be cause be a valcano eruption.
And im not saing that an earthquake cannot cause a landslide.



posted on Jan, 3 2005 @ 09:40 AM
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garpg says (re why a particular shift did not caue a tsunami):

"From my understanding with this particular quake in the Southern Ocean is that the plates moved horizontal and not vertical as with the Indonesian Quake. Therefore not causing the huge displacement of water upwards which would cause a Tidal Wave."

I am not familiar with the tectonic geology of that area, i.e., whether or not that particular plate boundary is divergent or subducting. But your hypothesis makes the most sense to me.

If you could find an Internet site that shows where the origin/epicenter of that particular quake was, and then cross-reference it to that area's type of tectonic movement, my guess is that you would've nailed it.



posted on Jan, 3 2005 @ 01:56 PM
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little 5.7 guy shook today. Last little guy was on Christmas eve. I wonder if this activity means something will happen somewhere else in the region again soon.



posted on Jan, 3 2005 @ 03:09 PM
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it must have something to do with how the grays placed the nuclear device


E_T

posted on Jan, 3 2005 @ 05:09 PM
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Originally posted by WyrdeOne
My fear, is that the 9.0 was an underwater volcanic eruption that might reoccur. That could explain the highly localized series of strong quakes. I mean, a trench 1000m long, 30m wide opened in the sea floor, more accurately exploded.
One damn big problem, big enough volcanic eruption would have caused huge plume of water vapour to rise from ocean... and there might be some thick pumice floating around India ocean.

BTW, previous big tsunami "hit" was one from Krakatau (between Java and Sumatra islands) eruption in 1883 when tsunamis killed 36 000 in Indonesia.
www.geology.sdsu.edu...
www.drgeorgepc.com...


E_T

posted on Jan, 3 2005 @ 05:18 PM
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Originally posted by Off_The_Street
Not necessarily. Any displacement can generate a seismic sea wave (tsunami); although a tectonic shift is the usual culprit, an underwater landslide (or even an above-water one that dumps a bunch of land into the sea) can start a tsunami.

That's the big fear about a tsunami striking the United States' East Coast; a seamount collapse near, say, the Azores could (not necessarily would) generate a large tsunami indeed, and devastate the East Coast cities of both North and South America.

As an aside, that's probably the only tsunami danger the East Coast folks have, since the only Atlantic tectonic boundary of note is a divergent one, not a transform or subducting one.

Lituya bay tsunami is good example about "above water" lanslide... whose tsunami climbed to half kilometer above sealevel when hitting to mountain flank on other side of bay.

Also those ones caused by Azores or Canary Islands could be that kind.

www.es.ucsc.edu/~ward/papers/La_Palma_grl.pdf
www.benfieldhrc.org...

And there's exception (aproving rule
) even in Atlantic, Lisbon quake 1755 caused tsunami.
www.benfieldhrc.org...





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