If we are thinking of the fire danger as being caused by climate change, the measures being taken by power companies would be called "climate adaptation." In pure disaster terms, limiting the potential for fires would be considered a "disaster mitigation measure." And, if you are in the fire service and think of this in fire terms, you could call the actions fire "prevention."
Right after the terrorist attacks of 9/11, there was a movement to replace the word "mitigation" (a phase of emergency management) with the word "prevention." After much dialog and pushback, both words were included included in the phases of emergency management with, as far as I can tell, prevention being more focused on human-caused, terrorist incidents.
I'm all for "keeping up with the times" and not opposed to the introduction of new terms. I, however, do not like it when people take a word like "happy" and redefine it as "glad" because they like that word better. Doing so confuses people.
Given that we have climate as an "existential threat," I'm going to go with the power shut off being an "adaptation" measure — not seen before.