The Colli Albani volcano (also known as Alban Hills volcano) is the large quiescent volcano that dominates the southern Rome (hereon Roma) skyline (Fig. 1). It covers almost 1600 km2 and its K-rich rocks have attracted the attention of geologists since the nineteenth century. The Colli Albani is one of the most, if not the most, explosive mafic volcanoes in the world. The state of activity of this volcano and its influence on the history of the Roma foundation has been heavily debated since Roman times by historians, scientists and archaeologists. As a result of recent detailed field surveys aimed at the redaction of the new Geological Map of Italy and of detailed studies prompted by the occurrence of gas eruption events and seismic swarms, new deposits related to previously unknown pre-Holocenic and Holocenic volcanic and phreatic activity from the most recent maar were revealed. This has changed the classification of the volcano from extinct to a still active and quiescent volcano, with important implications for the hazard to the city of Roma. The prehistoric and historic settlement history of the region and the foundation of Roma have been deeply influenced by this activity, as reported by several classical authors (e.g. Plutarch, Dionissus, Livy). In the fourth century B.C.E., the Romans dug a 1.5-km-long tunnel through the Albano maar crater wall to lower the crater lake level and prevent the dramatic overflows that had previously destroyed this region several times. This tunnel, which is still potentially functional, has to
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The Colli Albani volcano (also Alban Hills volcano) is the large quiescent volcanic field that dominates the Roman skyline. The Colli Albani is one of the most explosive mafic calderas in the world, associated with intermediate to large volume ignimbrites. At present it shows signs of unrest, including periodic seismic swarms, ground uplift and intense diffuse degassing, which are the main short-term hazards. New studies have discovered deposits related to previously unknown pre-Holocene and Holocene volcanic and phreatic activity. In the fourth Century B.C.E. Roman engineers excavated a tunnel through the Albano maar crater wall to keep the lake from breaching the rim and flooding the surrounding countryside, events that had previously destroyed this region several times.
The Colli Albani Volcano contains 21 scientific contributions on stratigraphy, volcanotectonics, geochronology, petrography and geochemistry, hydrogeology, volcanic hazards, geophysics and archaeology, and a new 1:50 000 scale geological map of the volcano. The proximity to Rome and the interconnection between volcanic and human history also make this volcano of interest for both specialists and non-specialists.