This has been a chronic problem for PG&E over the decades.
PG&E Guilty In 1994 Sierra Blaze / 739 counts of negligence for not trimming trees
When I first heard about the fires, PG&E failure to maintain trees was my first thought, but I couldn't bring myself to believe that they would do it again after being punitively fined for it before. If true, this is the kind of corporate negligence that warrants prison for executives.
-PJ
The causes of the fires have not been determined. In the meantime, do not demonize PG and E.