What "pecentage" of the earth's interior is on fire (volcanic)?

Answer 1

Zero Percent. Fire is the rapid oxidation of non-oxides and all materials in the Earth are in combination with oxygen or some other element. Also, the definition of volcanic is an igneous rock extruded onto the surface of the Earth. By definition a rock cannot be volcanic unless it is outside the Earth's interior.

Answer 2

Go to the site below.
None of the earth's interior is on fire, but some of it is molten (like a thick, super hot liquid).
The inner core is solid but the outer core is molten: Outer core: 30.8% of Earth's mass.
The transition region (7.5% of earth's mass) between the inner and outer mantle layers is at least partly molten and "part of the upper mantle called the asthenosphere might be partially molten". The entire upper mantle is about 10.3 % of earth's mass--so less than that. The earth's outer crust, which is only about 0.4-0.5% of the earth's mass, has a tiny bit of molten rock in volcanically active areas.

Answer 3

All of it I think. It's just that some fissures are closer to the surface of the earth than others.