Philosophical Transactions of the Royal Society of London Series A Mathematical and Physical Sciences · 1973 · 26 citations · 0 references
Natural SciencesEarth SciencesGeologySedimentologyStratigraphyVolcanologyVolcanic AshVolcanic Ash StratigraphyVolcanic DepositsVolcanic EruptionsVolcanic RocksVolcanic StratigraphyAsh Fall DepositsCrater Ejecta StratigraphyDeposit Grain Size DistributionPyroclastic Deposit StratigraphyPyroclastic Fall DepositsPyroclastic RocksVolcanic Ash DepositionVolcanic Ash Fall
The weakly explosive activity in May to June 1971 from the new explosion crater high on the eastern side of Etna produced a pyroclastic fall deposit which is very poorly sorted on the crater rim , but is well sorted farther away. Grain-size parameters are given for 47 sieved samples, seven of which were collected from the ash-fall during the eruption. The initial strombolian-type activity soon changed as pre-existing pyroclastic debris slid into the crater, and thereafter the ejecta included much non-juvenile material derived from this debris. The ash fell in the form of small damp flocculated clumps, but as it dried out much of the dust-grade material was blown away by the wind. Such dust may account for much of the loess-like soil found on the vegetated lower slopes of Etna.