This was on the news last night. I had the impression that the snow was uniformly distributed over the curved roof, but the thickness didn't appear to be more than about a foot.
From the picture it looks like a laminated wood arch.
Typically the base of the arch is outside of the building and possibly exposed to the weather.
If not properly detailed moisture can be trapped which can cause the wood to rot.
My guess is that the failure occurred at the base of the arch.
"'We believe it was excessive weight from the copious quantities of snow that we've had over the past 10 days,' Jim Murphy, who has owned the Rostraver Ice Garden since 1993, said Monday. 'We believe a laminated wood truss broke and that caused two other ones to go and the roof to pancake in that area.'"
"The rink, about 30 miles southeast of Pittsburgh...was built in 1965..."
This is my area, although I've never skated there.
NITTANYRAY: other local news video shows that the configuration is as you describe, so you're probably right.
My brother-in-law claims that the local ABC station showed security camera video on the news this morning. Anyone have a link? (Of course, you know how reliable brothers-in-law can be.)
I find it interesting that the news keeps referring to the failed member as a "truss" even though all every photo I see shows a glulam arch.
This is a little alarming to me. We've had less than 2' of snow since the last thaw. It doesn't seem like that should be enough to cause failure except in cases of unanticipated ponding, drifting, sliding, or unbalanced loading. (Which really should be anticipated, after all.) However, it seems like there are roofs coming down left and right around here.