Re: looking for clear explanation of the earthquake

[Dora Smith <villandra@austin.rr.com>]

Meor:

That article is not available online, and you don't give a complete
reference for the othe rone.

But I did find this quotation.

"In an India reference frame, Sundaland is moving due south so that the
motion is pure dextral strike-slip north of Sumatra. The predicted velocity
of India at the latitude of Myanmar is close to the rate of opening of the
Andaman Sea, suggesting low subduction rate along the Andaman front."

This sounds consistent with what the NEIS is saying casued the quake - but
it requires that the "India" plate and the Sunda plate are sliding past each
other rather than the India plate being subducted under teh India plate.
It also fails to explain how teh quake generated a thrust fault.   Thrust
faults are created by subduction, not by slipping and sliding.

Another mystery - this short abstract states that Sunderland is rotating
around some point south of Australia.

Has anyone ever claimed that Sunderland belonged to Gondaland?   I think
I've got that right - the supercontinent that included modern Australia and
Antartica.

Also, everything I'm fidning says that Sunderland is a shelf with teh
Indonesian Islands on it - and the "Sunda Plate" includes the entire
peninsula where Thailand and Vietnam are.

Yours,
Dora Smith
Austin, Texas
villandra@austin.rr.com
----- Original Message -----
From: "meor hakif" <hakif23@yahoo.com>
To: "Dora Smith" <villandra@austin.rr.com>; <dinosaur@usc.edu>
Sent: Thursday, December 30, 2004 12:04 AM
Subject: Re: looking for clear explanation of the earthquake


> --- Dora Smith <villandra@austin.rr.com> wrote:
>
> > Say, I bet there are people on this list who are
> > qualified to explain this.
> > Or maybe could tell me where to go to get an actual
> > clear logical
> > explanation.  There are specialists in Southeast
> > Asian plate tectonics at UT
> > Austin but they are on vacation and I can't reach
> > them.
> >
> > First of all, what are teh Burma and Sunda plates -
> > besides part of the
> > Eurasian Plate?
>
> Southeast Asia is considered by many authors to be
> moving independently of Eurasia, and it is called by
> some as the Sunda Block (The plate encompasses
> everything on the Sunda shelf, or Sundaland).It is
> "assumed" to be relatively stable in recent times,
> hence considering it as a single, rigid plate. During
> the Cenozoic, there was much more tectonic activity,
> with multiple changes in plate boundaries, including
> the separation forming the Burma block.
>
> You should try Hall (2002) for references
>
> Hall, R. (2002). Cenozoic geological and Plate
> Tectonic Evolution of SE Asia and the SW Pacific:
> Computer Based Reconstructions, Models and Animations.
> Journal of Asian Earth Sciences 20(4): 431p.
>
> And yes, definitely Dilong.
>
> Meor,
> University of Malaya
>
> --- Dora Smith <villandra@austin.rr.com> wrote:
>
> > Say, I bet there are people on this list who are
> > qualified to explain this.
> > Or maybe could tell me where to go to get an actual
> > clear logical
> > explanation.  There are specialists in Southeast
> > Asian plate tectonics at UT
> > Austin but they are on vacation and I can't reach
> > them.
> >
> > First of all, what are teh Burma and Sunda plates -
> > besides part of the
> > Eurasian Plate?
> >
> > Is the Burma "microplate" actually just a zone of
> > loose rock and faults?
> > It appears to constitute the entire region
> > immediately east of the java/
> > sunda trench, which is the point where the
> > Australian and Indian plates
> > (which of those plates is actually there and whether
> > they are two plates is
> > clearly a matter of controversy) slides under the
> > Eurasian plate.   Why is
> > the Burma plate or microplate called a plate at all?
> >    Logically it is a
> > fault zone, probably uplifted above the trench.
> >
> > On one of the faults in the area I found evidence
> > that some rock tries to
> > move out of the way, along the fault zone.   Is the
> > Burma plate an area of
> > crust that is behaving in this way?    That would
> > logically account for
> > NEIS's insistence that the India and Australia
> > plates move northward as well
> > as eastward with respect to it ( though it would
> > require that the Burma
> > plate in fact be moving south) - and that there are
> > slip/ slide faults along
> > the boundary.
> >
> > WHAT exactly is the Sunda plate, and why is it
> > called a separate plate?
> > The Sunda plate is part of the Eurasian plate and
> > not usually depicted as a
> > separate plate.   In fact before last night I could
> > find next to nothing
> > about it in Google, except that two countries sit on
> > it.    I have been
> > unable to find a map that shows the entire Sunda
> > plate, but it appears to
> > constitute Burma, Thailand, and Vietnam, and the
> > Indonesian islands to the
> > north and east of the java trench/ island arc formed
> > where the Australian
> > and Indian plates meet the Eurasian Plate.    On the
> > western border, it
> > meets with the Pacific plate, and its rigidity
> > relative to plates around it
> > purportedly causes trouble for Bali and another
> > nation that sits on its
> > boundaries.
> >
> > I didn't find anything that says it moves
> > differently with respect to the
> > rest of the Eurasian plate or something - which is
> > the rationale for
> > thinking there is an Indian plate separate from the
> > Australian plate.    I
> > found a whole article showing that those two paltes
> > move differently with
> > respect to each other though thye have a poorly
> > defined border and noone can
> > decide where it is.
> >
> > Speaking of noone knowing where the boundary is
> > between the India and
> > Australia plates, where is it?   Before yesterday,
> > the eastern border of teh
> > India plate was I think the mid-ocean Ninety-east
> > ridge.    Now suddenly the
> > India and Australian plates have an east-west
> > boundary that ends at the java
> > / sunda trench off of northern Sumatra, near where
> > the quake occurred - and
> > that helped cause the earthquake.
> >
> > Now the part I REALLY don't understand.   NEIS's
> > explanation of how the
> > quake happened - which I found more or less
> > paraphrased elsewhere.    The
> > India and Australia plates move northeast with
> > respect to the Eurasia plate
> > and subducts underneath it where the plates meet.
> > Logical so far.    Where
> > this takes place there are thrust faults.   Also
> > logical.   It more or less
> > requires that parts of the Eurasia plate are thrust
> > upward at the boundary.
> > That in fact created the entire island arc.
> >
> > Now for not logical.    According to NEIS, the India
> > and Australian plates
> > also move northeast with respect to the "Burma
> > microplate", which makes
> > slip/ slide faults like the San Andreas fault in
> > California, where two
> > plates glide sort of smoothly past each other.
> > Occasionally they hang up,
> > and when the rock breaks there is a quake.  Then the
> > two plates continue
> > their seperate northward and southward journeys.
> > Quakes in California do
> > not result in land near the fault thrusting upward.
> >
> > According to NEIS, as paraphrased in various places
> > with no other detailed
> > explanation of the quake available, this quake
> > resulted from a rock breaking
> > loose along a SLIP/ SLIDE fault, between the India/
> > Australia and Burma /
> > Eurasia plates.    When that happened, a nine- mile
> > wide strip along the
> > entire near boundary of the Burma/ Eurasian plate,
> > abruptly SLIPPED, and
> > THRUST a hundred feet UPWARD.    That just doesn't
> > sound like something a
> > slip/slide fault could do.
> >
> > How is this even possible?   Is what really happened
> > that the Australia/
> > India plate got stuck while sliding UNDER the Burma
> > plate, and when it broke
> > free the edge of the Burma plate abruptly thrust
> > upward?     That would be
> > far more logical.
> >
> > By the way, is there ANY justification for thinking
> > that New Zealand sits on
> > its own plate?  Two plates meet and twist in a
> > bizarre way there - hard to
> > see how there could be a separate plate, nor how
> > there would be just ONE
> > separate plate, logic says there would have to be
> > two;  but maybe it's a
> > Burma microplate sort of thing?
> >
> > By the way, the best single article I have seen on
> > the quake by far is at
> >
> http://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake,
> > and there are
> > links to the main media web sites on the quake,
> > which is more than google
> > news has managed to do.
> >
> > Yours,
> > Dora Smith
> > Austin, Texas
> > villandra@austin.rr.com
> >
> >
>
>
>
>
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