I suspect that this is intentional, and a desired outcome rather than an act of arson. These are oil refining stacks, and the process of making petroleum involves making methane that ends up being discarded.
The black smoke above suggests that they’re already burning it inside the smoke stack, but the mixture is low on air (think: carbon monoxide), so the smoke stacks often burn the top of the stack in order to further reduce the methane concentration.
