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Source of NEIS schematic of Andaman tectonics - and they misread it
I THINK I already posted the first part of this but not sure - I know I
posted it to two newsgroups.
I called up Joseph Curray, of I think the Scripps Oceanic Institute, because
I found an abstract of something particularly clear that he wrote about
Andaman Sea tectonics, northern Sumatra, and the fault lines. He told me
that the NEIS schematic of the Burma microplate is plain wrong - the sliver
arc is the Burma microplate, and it runs from northern Burma past Java.
Past Sumatra, anyway. He referred me to a forthcoming article in JAES -
Journal of Asian Earth Science, I think. I just sorted all of my
printouts into a binder and lost track of where I wrote it down.
I also heard from someone else I wrote to, and he wrote that the notion of
plate boundaries breaks down off of northern Sumatra because the situation
is too complex.
I heard back from the folks at NEIS - and Stuart Sipkin said that the
schematic they used came from Peter Bird's data (UCLA) and is the most well
Hmmm.... after persistent searching in Google for Peter Bird's data, I
found it. See below.
He writes, " P.S. Now that the Banda Aceh earthquake has focused attention
on the area around the Andaman Sea, you may see reproductions of these plate
boundaries on regional maps by others. In some cases, the grid pattern for
the "Persia-Tibet-Burma orogen" has been omitted. This is unfortunate,
because the grid is a warning that plate boundaries in the gridded region
are oversimplified and not to be taken literally. In particular, the curved
fault under the Irrawaddy delta, separating the BU and IN plates, may not
exist. It is merely one hypothetical solution to the kinematic problem of
how to accomodate the relative rotation of these two plates. (Of course,
any other solution is likely to imply a similar seismic hazard.)"
This web page has beautiful maps of his scheme of the world's
tectonics -where he has his "orogens" (regions where it is not possible to
be sure what is going on) in cross-gridded lines. He also has a 50 page
paper linked to that page, in which he examines the entire history of the
discussion of east Asia's microplates and their boundaries in detail, and
reiterates that his lines are not intended to be taken literally.