Unlike mud volcanoes, the Yanar Dag flame burns fairly steadily, as it involves a steady seep of gas from the subsurface. There is no seepage of mud or liquid, which distinguishes it from the nearby mud volcanoes of Lökbatan or Gobustan. It is claimed that the Yanar Dag flame was only noted when accidentally lit by a shepherd in the 1950s.
On the territory of Yanar Dag, the State Historical-Cultural and Natural Reserve was established by the Presidential decree dated 2 May 2007, which operates under the control of the State Tourism Agency of Azerbaijan. After a major overhaul between 2017-2019, Yanardag Museum and Yanardag Cromlech Stone Exhibition were launched in the area of the Reserve.
In the first millennium BCE, fire played a role in the Zoroastrian religion as the link between humans and the supernatural spheres.
The Yanar Dag fire is never extinguished. Around this open fireplace, the atmosphere is filled with the smell of gas. The flames emanate from vents in sandstone formations and rise to a height of 10 metres (33 ft) (different figures are mentioned in other references) at the base of a 10-metre-wide (33 ft) scarp below a hillside. Yanar Dag is described by the Geological Survey of Azerbaijan as "Intensive flames, to 1 metre (3 ft 3 in) high, develop for 15 metres (49 ft) along the base of a 2–4-metre-high (6.6–13.1 ft) and 200-metre-long (660 ft) tectonic scarp." The surface flames result from the steady gas emissions from underlying soils.
Even the surface of streams near the Yanar Dag fire can be ignited with a match. These streams, which otherwise appear calm, are known as Yanar Bulaq: "burning springs." There are several such springs in the vicinity of the Vilascay River, where the local people take curative baths.
Only a handful of fire mountains exist today in the world, and most are located in Azerbaijan. Due to the large concentration of natural gas under the Absheron Peninsula, natural flames burned there throughout antiquity and were reported on by historical writers such as Marco Polo. During one of his visits to the area, Alexandre Dumas described a similar fire he saw in the region inside one of the Zoroastrian fire temples built around it.
Most mud volcanoes are located off the Baku‐Shamakha road, about 40 kilometres (25 mi) from the city.
The reason offered for the Yanar Dag fires is the result of hydrocarbon gases emanating from below the earth's surface. Apart from Yanar Dag, the most famous site of such a fire is the Fire Temple near Baku, off the Greater Caucasus, a religious site known as an ateshgah, meaning temple of fire. It has also been inferred that such fires could be the cause for "thermal metamorphism."
As the flames of Yanar Dag, the Ateshgah of Baku's flame was a manifestation of the seepage of natural gas from porous strata, but the natural flow at Ateshgah ceased some time ago, and the flames seen there now are fed from a gas main for touristic effect -. In contrast, those at Yanar Dag are still entirely natural.
According to a study carried out by the scientists and geologists of the Geological Survey of Azerbaijan, analyses of four samples taken from Yanar Dag revealed that the area of maximum flux was situated at the upper side of the fault scarp - the very area from which the flames emanate. The value of microseepage recorded was in the range of 103 mg m−2 d−1 at approximately 30 metres (~100 ft) from the fire on the upper part of the study area. It has been inferred that the degassing area is larger than the measured area, and it is very likely that the microseepage is pervasive along the fault zone. This fault scarp is inferred as a part of the huge Balakhan-Fatmai structure on the Absheron Peninsula.
To protect this landmark and support tourism in the area, the Yanardag State Historical, Cultural and Natural Reserve was established by presidential decree dated 2 May 2007. It operates under the control of the State Tourism Agency and is located in the village of Mammadli (Absheron Rayon). After major overhauls between 2017-2019, the Yanardag Museum and Yanardag Cromlech Stone Exhibition were launched within the territory of the Reserve. The Reserve covers an area of 64.55 hectares with a 500-seat amphitheatre for outdoor concerts. It features a 3-zoned museum with exhibitions displaying ancient stones and pieces of craftsmanship used by locals. There are also tombstones, ancient kurgans, and two burial grounds with historic graves.