The volcano is responsible for the largest active lava flow in the entire Solar System, with recent flows dwarfing those of even other volcanos on Io.
Amirani consists of a half-circle shaped, 37 kilometres (23 mi)-wide volcanic pit, which is connected to a 330 kilometres (210 mi)-long compound lava flow by a narrow channel. The southern half of the Amirani flow field is surrounded by a circular, bright sulfur dioxide diffuse deposit, created by a sulfur-rich volcanic plume. The volcano was first observed in images acquired by the Voyager 1 spacecraft in March 1979. Later that year, the International Astronomical Union named this feature after an Georgian fire god, Amirani.