I have some new information about "Samarra."
First, the Iraqi blogger Omar, whom I emailed to ask about the stress pattern, kindly replied to say
the word is : Sa----ma---rra.
so the stress is on the last syllable (iraqi way)
and in formal arabic, it's: Sa--ma--rra'
Thus Iraqi colloquial deletes the final glottal stop, but the stress remains final, just as Mohamed Maamouri suggested (he is Tunisian, but he knows a lot about Arabic linguistics and has visited Samarra). I believe that Omar is talking about the kind of Arabic spoken in Baghdad (what Ethnologue calls Mesopotamian Spoken Arabic, code ACM).
Second, Mohamed Maamouri wrote again:
I was not pleased yesterday that even though I thought of a possible etymological link to /samar/ the name /samarraa/ did not have a good morphological grounding. When I woke up this morning, I remembered one of my high-school lessons which gives the explanation of the exceptional word-formation ('morphosyntactic amalgam' ?!) of /samarraa/ which comes from /sarra man ra?a:/ '/delights/cheers (he/she) who sees [it]''. This etymology is attested in the literature of the period.
Finally, Tim Buckwalter added:
You are absolutely right, and I just found it in the ALECSO dictionary, although they give it in the passive: sur:a man ra:?a (i.e., the town of "happy-is-he-who-sees-it"? )
and Tim noted as a postscript that
This Google is very productive: "surra man ra'a"
One of the more interesting historical links is this one, which says that
Posted by Mark Liberman at December 2, 2003 03:42 PM
The ancient toponyms for Samarra are: Greek: 'Souma' (Ptolemy V c. 19, Zosimus III, 30), Latin: 'Sumere', a fort mentioned during the retreat of the army of Julian the Apostate in AD 364 (Ammianus Marcellinus XXV, 6, 8), and Syriac 'Sumra' (Hoffmann, Auszüge, 188; Michael the Syrian, III, 88), described as a village.
[. . .]
The caliph's city was formally called Surra Man Ra'a ("he who sees it is delighted"). According to Yaqut (Mu`jam s.v. Samarra), this original name was later shortened in popular usage to the present Samarra. It seems more probable, however, that Samarra is the Arabic version of the pre-Islamic toponym, and that Surra Man Ra'a, a verbal form of name unusual in Arabic which recalls earlier Akkadian and Sumerian practices, is a word-play invented at the Caliph's court.