The history of the Monti Sabatini and Alban Hills volcanoes: groundwork for assessing volcanic-tectonic hazards for Rome

The volcanic rocks of Rome provide chronostratigraphic constraint that is of use to geologists, archaeologists, and paleontologists. Identifying the areal distribution of these rocks, their mode of emplacement and a detailed chronology of the eruptive events also, is crucial for assessing local natural hazards in a volcanic-tectonic context, and for recognizing whether the volcanoes may erupt again in the future. We have identified and dated many of the volumetrically significant eruptive units from the Monti Sabatini and Alban Hills (Colli Albani) and propose a formalized volcanic stratigraphy for Rome. It is probable that seismic events triggered some eruptions, as several ignimbrites from the two volcanoes have statistically indistinguishable ages. Following a 200+ kyr period of dormancy that was coincident with a pulse of regional uplift, the Alban Hills appears to have begun recently (circa 45 ka), a new eruptive cycle. Therefore, accurate assessment of volcanic-tectonic hazards, and estimation of possible future volcanic activity, is necessary for the safety of the five million people living near these volcanoes.