Re: looking for a clear explanation of the earthquake

[David Marjanovic <david.marjanovic@gmx.at>]

> Now right there this doesn't make sense.   The Burma plate sits between 
> the
> Indian/ Australian plate(s) and the Sunda plate in the entire region where
> Sundaland allegedly moves straight south while moving straight east. 
> What
> does the Indian/ Australian plate(s) do

Move straight north.

> when it gets to the Sunda plate on the other side -

Which other side?

> What I want is a simple plain language explation of what these plates are,
> wehre they are, and how tehy contributed to the earthquake, if they did.

I'll try to explain the big picture... in terms that look simplified but 
aren't because I don't know it any better.
       India pushes north and squishes basically all of east and south Asia 
out to sea -- to the Pacific and Indian oceans. South China goes southeast, 
Sunda goes south and Burma goes southwest. Sunda happens to go south as 
precisely as India and Australia go north. Therefore a small part of the 
Sunda-Indian plate boundary apparently experiences (anti)parallel motion of 
the two plates instead of subduction. I think the earthquake happened more 
or less there where this strike-slip fault (in the north) has its transition 
to the subduction zone (in the south).

> The way all my sources describe a strike/ slip fault, they are two
> dimensional, and if something changes altitude, it drops.    So something
> wouldn't thrust suddenly upward.

Everything's relative. One drops, or the other bounces up. Or both.

> You're right, it might be true that there was more than one kind of motion
> at once - though atleast analytically that is not logically possible. 
> Two
> plates cannot slide smoothly past each other and under each other.

When a plate boundary is curved enough, it can be a strike-slip fault in one 
place and a subduction zone (or midocean ridge) in another.