جوان ترین فعالیت آذرآواری درآتشفشان دماوند، نمونه‌ای از یک فوران ساب‌پلینی با ارتفاع ‏ستون فوران در استراتوسفر

Damavand is a stratovolcano and has power full explosive eruptions during its activity. pyroclastic products in damavand volcano has been ‎mostly deposited as pyroclastic fall and flow deposits. pyroclastic fall deposits in some locality extending up to 20 km from the summit. ‎damavand pyroclastic deposits cover much of the eastern and southern flanks of the volcano suggested that during the eruption, tephra ‎dispersal axes was toward to the east. there are a major young pumice deposits, named as karam poshteh pumices, are identified and ‎consists of a coarse-grained pumice fall deposit with proximal welded facies dispersed to the west, but lacks pyroclastic flow deposits with ‎provisional ages in the interval > 7.3 ka and < 25 ka.this young pumice fall deposit is distributed over much of the western and south-western ‎flanks and is located at the foot of the steep damavand cone at the mouth of a ravine where the proximal welded facies is well exposed on ‎the ravine walls. the deposit can be divided into thin more distal unconsolidated pumice fall deposits and think proximal welded pumice fall ‎deposits. karam poshteh deposits also consist of welded beds of pale pink pumice with minor cross-layered ash beds. atmospheric ‎information, in particular wind data, is crucial in order to perform tephra dispersal simulations. tephra transport and sedimentation is ‎controlled by wind in the atmosphere and is a function of wind velocity and provenance for tropospheric and stratospheric levels. mehrabad ‎meteorological station is supplied wind data at different altitudes. we apply and intemperate wind data between 1995 to 2010 at damavand ‎volcano to understand regional distribution of tephra fall. westerly winds are persistent during winter and summer time at troposphere. the ‎most prominent features in the stratospheric circulation are a westerly jet in the winter hemisphere and low velocity easterly jet in the ‎summer hemisphere. easterly jet in the summer implies that westward transport of tephra in karam poshteh. ‎