آتشفشان سبلان

Sabalan volcanic summit (volcanic phenomenone)
This volcano is a third high mountain with 4815 m altitude. Sabalan has been located at west- north Iran and it is a volcano from strombolian type. A big caldera of this volcano is a distinguishable and determined with 20km diameter and 400 m subsidence completely.

http://www.gsi.ir/geoturism/en/state/Ardabil