There is this clip from BBC/Persian showing Damavand blowing off steam! یک استاد زمین‌شناسی: خروج بخار آب از دماوند بخشی از یک روند طبیعی است - BBC News فارسی

Ever wonder how the mountain got its name? Well, here it is: The word dam(a) means steam in Old Persian and vand (like band) means mountain in Old Persian (Arabic: fand).