During the Cedar fire, four years ago, there was so much talk about this phenomenon then, as well. What actually happened, apparently, is that the fires were so hot and so fast moving than the fires burned the leaves off the trees and scorched the trunks. The eucalyptus trees are nicely producing new leaves and thriving since the Cedar fire. That obviously would never happen if the tree exploded.
Like I said, with all the coverage of the fires, I have never actually seen a eucalyptus tree explode. Has anybody?
Probably one of those theoretical possibilities that could happen or has happened under specific circumstances. Then again, could be just airhead MSM reporting. There was a reporter on a San Diego Station earlier that was watching a fire bulldozer try to catch up to a control burn that was running away from him. She stated that what he was doing was pushing the fire with his bulldozer. Eventually he told her what happened and told her to evac immediately.
Just heard reported that Camp Pendleton Commander stated that from 20,000 to 23,000 vehicles were escorted out of the Fallbrook evac zone through the base and onto the 5 freeway. No one knows what is happening up there now.
I don’t think it’s “explode” like a bomb, or like dynamite, but more the way the oils in the tree cause the foliage to just burst into flame when subjected to the heat of an approaching blaze. It’s far more dramatic with pines, as they have turpentine in them, which is more flammable than eucalyptus oil.
I don’t know that there are any natural conditions that could stoke a eucalyptus up hot enough to where the actual tree trunk would explode into flames. You’d have to have a very hot fire around the same tree, for a very long time. Volcanism would be about the only possible way that nature could create that kind of scenario.
I think that "explode" just means that when they finally burn, they burn very rapidly, sending up large gusts of flame. That was what happened during the Oakland Hills fire. Eucalyptus trees were blamed for worsening that fire with their explosions, but I do not believe it was ever proven.
The trees do have an odd habit of auto-amputating large branches on warm windless summer days, once to the detriment of my car's hatchback. Since you live in San Diego, you have probably heard of eucalyptus branches falling on unwary tourists as they strolled through Balboa Park.