By coincidence, soon after I made the above post, 2 issues of EOS, Transactions AGU, arrived in the mail. The Nov. 29 2005 issue has an article by Satish Singh and a bunch of French on their multibeam bathymetric survey of the Sumatra-Andaman rupture zone. They mapped the seafloor trace of what they think is a right-lateral strike-slip fault for 100s of km west and northwest of northern Sumatra, called the West Andaman Fault (WAF). They even say that "In this case, a large portion of the southern WAF may break in the near future, not the SF as previously suggested...." (SF I guess is Sumatra fault). Elsewhere in this paper, they say that near future is years to decades........In my opinion, even if this fault or the offshore part of the Great Sumatra Fault failed in a very large earthquake, it would not produce a large tsunami, if it produced one at all, as explained in my previous post.

Geology is not like Physics or mathematics: there are usually not black and white answers...it is all shades of gray...
Chris