Volcanism and deformation since 12,000 years at the Campi Flegrei caldera (Italy)

The Campi Flegrei caldera is a restless, nested structure resulting from two major collapses related to the Campanian Ignimbrite (37,000 years BP) and the Neapolitan Yellow Tuff (12,000 years BP) eruptions, respectively. Detailed stratigraphical, structural, volcanological and C-14 (AMS) geochronological studies, devoted to the reconstruction of the volcanic and deformational history of the Campi Flegrei caldera in the past 12,000 years have been carried out. The results of these studies show that in this time span, intense both volcanic and volcano-tectonic activity was confined inside the Neapolitan Yellow Tuff caldera. Volcanism was concentrated in epochs of intense activity, alternating to periods of quiescence. The I epoch lasted from 12,000 to 9500 years BP giving rise to 34 explosive eruptions, each every 70 years on average. During the II epoch, dated between 8600 and 8200 years BP, six explosive eruptions took place at an average interval of 65 years. The III epoch lasted from 4800 to 3800 years BP and produced 16 explosive and four effusive eruptions which followed each other at mean intervals of 50 years. Eruption vents of the I epoch were located mostly along the marginal faults of the Neapolitan Yellow Tuff caldera, while those of the II epoch aligned on the northeastern sector of this margin. During the LII epoch volcanism was confined in the northeastern sector of the Neapolitan Yellow Tuff caldera floor. The caldera floor is disjointed in blocks with variable vertical movements by fault and fracture systems mainly trending NE-SW and NW-SE. The still active resurgence of the caldera floor began soon after its collapse. Onset of bath II and III epoch of activity coincides with increase in resurgence rate of La Starza marine terrace, the most uplifted part of the resurgent block. (C) 1999 Elsevier Science B.V. All rights reserved.