Fig. 1: Summary of observations.
a Map of the study area. Global Positioning System velocities in a Tyrrhenian reference frame43. The trace of Irpinia70 is shown in red. Carbonate rocks are represented with green overlays. Background color-coding shows the secular tectonic strain rate (second invariant of the strain rate tensor). The inset shows the location of the study area in Italy. b Enlarged map (area enclosed by the black line in a) showing 2008–2022 seismicity from the Irpinia Seismic Network. Colored dots represent the considered declustered seismicity within the first 12 km of depth and above the completeness magnitude, white dots represent other not-considered seismic events. Global Centroid Moment Tensor focal solution and surface projections of the three faults28 responsible for Ms 6.9, 1980 Irpinia earthquake with its focal mechanism; green patches enclose shallow carbonates rocks; c Time series of hydrological, seismological and geodetic observations. The upper panel shows the discharge measured at Caposele spring. Lower panels show velocity variations (green circles, inverted sign) for coda waves time lapse using empirical Green’s functions reconstructed by autocorrelation of seismic noise recorded at MCRV and CAFE in the frequency band of 0.5‐ to 1‐Hz (blue dots) together with East components of displacement at the same stations (red circles); d conceptual model of the modulation of crustal deformation induced by variable hydraulic head in karst aquifers. εxx indicates the horizontal strain in the ENE-WSW direction.
