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Avellino Eruption
The Avellino Eruption of Mount Vesuvius refers to a Plinian-type eruption that occurred in the 2nd millennium BC and is estimated to have had a VEI of 6. It is the source of the Avellino Pumice ((イタリア語:Pomici di Avellino)) deposits named from the comune of Avellino in Campania where they have been found extensively.
==Characteristics of the eruption==
"Assessment of volcanological factors" in one scientific study reconstruct a minimum eruption time of 3 hours in which an initial explosion raised a column of and deposited about 0.32 km3 of white pumice ("the white pumice phase"), while a second, more intense explosion raised a column of depositing 1.25 km3 of grey pumice ("the grey pumice phase"). These pumices appearing in Apulian pottery can be used to establish relative chronology of pottery phases.
A 2008 study of the lithofacies (deposits from the eruption) distinguishes three phases. Pyroclastic flows (PDC's) of Phases 1 and 2 were generated by "magmatic fragmentation" and had "small dispersal areas" mainly on the slopes of Vesuvius. Phase 3 was created by "phreatomagmatic fragmentation," in which clastic fragments are driven by superheated steam from ground water mixed with the other gases released from the magma. The authors characterize Phase 3 as "the most voluminous and widespread in the whole of Somma-Vesuvius' eruptive history." Some facies a few cm thick were found from the source. The vent was west of today's center.
The overall results of the Avellino Eruption were catastrophic and widespread. The deposit thickness of ash and other eruptive material ranges from 15m close to the vent to 50 cm around Avellino, as well as creating a subaquaeous debris-flow in the bay of Naples.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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