I agree that deaths have to be meaningful in some way, such as to move the plot along or make a point. I'm currently working on a novel that involves a major volcanic eruption - not on the scale of Yellowstone, more like Pinatubo in 1991. The major characters are all scientists who are monitoring the volcano. One of the main themes is that actually, in a major disaster like this, you can't save everybody - even if you evacuate everyone from the worst affected areas. And yes, there are references to the fact that quite a lot of people die. But I'm only going to kill off two of my characters. One guy (informally nicknamed Mr Redshirt as I've yet to settle on a proper name) gets nailed by a volcanic rock in the first chapter. This serves several purposes. It causes the scientists to start considering the possibility that the volcano (which has been dormant for several thousand years) might really be waking up. It lets the readers know that even though some of the scientists are sceptical of the possibility, the volcano might really be waking up. And it lets the readers know that even the scientists - the experts - are not immune to potentially being killed. (It also removes an extraneous character who I was having trouble developing, but let's pretend I didn't just say that.) The other death happens at the climax of the novel, during the actual eruption, when one of the scientists falls of a roof while clearing it of volcanic ash. I needed a way to resolve the romantic subplot that fit the overall tone of the novel and fit with the plot devices already used, and the only realistic way to do that was to kill off one of the two characters involved. I couldn't come up with a way to kill her without putting everyone else's survival in question, and "everybody dies" is only an acceptable ending if you're writing about Pompeii, so it had to be him. It brings the antagonist's storyline to a climax, as the antagonist is on the roof with him (in an attempt to redeem himself, NOT to push him off!!) when the accident happens. Finally, it rams home the point that some disasters are so big you can't save everyone. The guy who dies is the most experienced in the whole group, the one who best knows what he's doing... and he still dies. It literally hurt to write (he's my favourite character in the novel and probably my favourite character I've created full stop), but it was absolutely necessary to the story. I wouldn't have done it otherwise.
