The restless, resurgent Campi Flegrei nested caldera (Italy): constraints on its evolution and configuration

We have collected new stratigraphic data in the Campi Flegrei caldera through surface geological mapping and study of cores drilled to various depths. We integrate these data with geological, geochronological and geophysical constraints available in the literature to reconstruct the volcanic and deformational history of the caldera. The caldera is a resurgent, nested structure resulting from two main collapses related to the Campanian Ignimbrite (37 ka) and the Neapolitan Yellow Tuff (12 ka) eruptions. While the structure is affected by a broad subsidence, ongoing local resurgence and unrest occur inside the younger, nested caldera structure. Although most of the caldera floor consists of multiple structural blocks due to long-term deformations, magmas were able to erupt only in one sector of the resurgent part. The caldera has shown signs of unrest during the past 25 years, with short-term deformations that have generated a net uplift of 3.5 m. The short-term deformations are related to the Neapolitan Yellow Tuff caldera resurgence and interpreted as the net result of brittle and ductile components. The long-term deformations likely represent the sum of the permanent, brittle component of each short-term deformational event.