Mud volcanoes in Gobustan

Over a thousand mud volcanoes are known to exist in the world, and some 400 of those are in the coastal area of Azerbaijan. Every 20 years or so, one of these mud/gas volcanoes will ignite deep below the surface and create a massive explosion. Mud volcanoes are closely associated with hydrocarbon and petrochemical stores underground, hence the gas trying to escape to the surface.