Question: Are there actual cases of green flames comming from the ground? I think it looks quite cool, but do things like that actually exist? The only thing remotely similar that I know is the Door to Hell in Turmenistan, which is a collapsed methane drilling project that was ignited to prevent the gas from mixing with the atmosphere. However, it is a man made gas leak, consist of only a single hole, and burns red.
Is it possible to have small green flames sprad over a large area?

Green fire can be made by mixing Zinc and sulphur so any zinc heavy mineral region with volcanic activity could easily be a good reason for green fire.