Figure 2: Reconstruction of the elevation (m above the sea level in 1905 – first leveling by Istituto Geografico Militare) through time at 20 selected sites within the Campi Flegrei caldera, obtained integrating geological, historical and archaeological data.

The elevation is referred to the nearest benchmark or to archaeological structures. The uplift rate (cm/yr) calculated for the periods 1251–1400, 1400–1536 and 1536–1538 is reported in green. The location of the sites is reported in Fig. 1, from Miseno (benchmark 58) to Nisida (benchmark 194). Error bars are in red. The diagrams highlight the difference in elevation changes between the benchmarks close to the caldera centre and those near Monte Nuovo. During 1251–1400 the caldera floor underwent a minor uplift, with maximum values in the Pozzuoli area. From 1400 to 1536 a general and sharp increase of the uplift rate still culminates in the Pozzuoli area. Immediately before the eruption (1536–1538) the uplift reaches the highest rate in the area of opening of the future vent (Mt. Nuovo). Data by the authors.