Okay, as much Fun as tantrum spirals can be, there should be some method of dealing with them, or at least running damage control.
My fortress of about 110 dwarfs suffered 8 casualties in a goblin siege. Of course there was massive tantrums and unhappiness after this (most of my dwarfs were estatic prior to the siege) and that has lead to a massive number of melancholy and beserk dwarves. Luckily most of my beserk dwarves went nuts in their rooms, so I just lock the door and let them stew. But every now and then one goes nuts in a public place, and ends up killing another dwarf which seems to start the spiral anew. I have tried posting military dwarves in public areas but thats only a stopgap method that fixes the result not the cause.
as I said, I had 110 dwarves prior to the siege, 102 after the siege, I now have 57 dwarves left over including a small migration, and some are still beserk and melancholy.
okay enough backstory.
The problem is that the dwarven leadership, that is the stink'n nobles, cant take an active role in helping quell the unrest amongst the populace. Sure the Mayor will have a chat with a tantruming dwarf, but thats a one on one situation in a fortress with a large population that is frothing at the mouths. What wold be another option is to have a noble enacted party/celebration. It would be an option you'd turn on at the option menu, during this time there is a permenant party in all meeting areas, in which dwarves with a low happiness score would go and celebrate, also during this time, dwarves consume 2x as much food/booze as normal. The aim of the party would be more focused on resolving the issues stemming from happiness loss that cant be combated by standard methods.
Pros: Active Defense at a total collapse due to tantrums.
Cons: Increased Food/Booze consumption. Lower effeciency as dwarves party more often. Dwarves Socialize more which could lead to further spirals.