pyrophile

from The Century Dictionary.

• noun A lover of fire; specifically, one who explains volcanoes by the natural internal heat of the earth, as opposed to electrical or other cause contributed from outside.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A creature that likes and delights in the presence of fire
• noun dated, rare A person who accepts that the energy of volcanos originates from the heat of the Earth's interior
• noun A pyromaniac