My van was towed to a shop in town this morning.  We'll see what they
find after they replace the belts.  They'll use the Gates belts
recommended here.

Regarding the failed belts: My belts were installed by a reputable VW
shop in California last December, only about 10,000 miles ago.  So not
that old.  (I didn't note the brand.)

It's the alternator/water pump belt that has obvious damage.  The power
steering belt looks undamaged, so I hope it just got thrown when the
other belt did.  I'll keep the latter as a spare and lay in a new belt
as a spare, too.