Tephrachronology in non-volcanic areas: principles, methods of investigation and state-of-the-art in Italy [Tefracronologia in aree non vulcaniche: Principi, metodi di indagine e stato dell'arte nel contesto Italiano]

Fallout tephra layers from powerful explosive eruptions are isochronous marker beds, which can be used to correlate, and possibly to date, quaternary marine and continental sedimentary sequences, even if at a great distance from one another. It can thus be said that tephrachronology is a useful tool for the reconstruction of natural events over wide areas, particularly in non-volcanic regions. General principles of the tephrochronological method and main techniques of investigation, both in the field and in laboratory, as desumed from the up-to-date bibliography, are outlined in this paper; results of those tephra studies which are of interest for the Italian context are reported. These mostly concern deep-sea records; in spite of their potentiality in areas adjacent to the Italian quaternary explosive volcanoes, tephra studies have been scarsely carried out until now in terrestrial deposits.