GNGTS 2019 - Atti del 38° Convegno Nazionale

8 GNGTS 2019 S essione 1.1 mainly rightward movement of the footwall. The coseismic dislocation induces the volumetric contraction of the hangingwall at depth, thus recovering the volume dilation occurred in the interseismic phase, while dilation occurs in the shallower 1-2 km. For the Emilia 2012 reverse-fault event, the displacement pattern emphasises the hangingwall uplift (Fig. 3f), which induces volume dilation in the hangingwall at depth and contraction in the shallower part. The footwall undergoes extension and compression in its upper and lower parts, respectively, because of its leftward movement. Since the models are fluid saturated, coseismic volumetric changes develop a Δp pattern in excess to the hydrostatic (Fig. 3g and h). In detail, suprahydrostatic pore pressures develop in areas affected by volumetric compression, Fig. 3 - Interseismic differential displacements (panels a and c) and volumetric strains (panels b and d) caused by the interseismic shearing of the deeper fault segment (green segment n°1 in Fig. 2), calculated for the L’Aquila 2009 and the Emilia 2012 events. Positive volumetric strains indicate dilation, while negative volumetric strains indicate contraction. Coseismic differential displacements (panels e and f), and pore pressure excess (panels g and h) caused by the unlocking of the shallow fault segments (red segment n°2 in Fig. 2). The yellow stars in panels e and f locate the position of the mainshock. Postseismic Δp pattern after 20 days from the simulated earthquakes (panels I and j) and cumulated postseismic displacements after two years from the simulated earthquakes (panels k and l). Comparison between the InSAR and modelled LOS displacement profiles along sections A and B in Fig. 1a for the L’Aquila 2009 (panel m), and Emilia 2012 (panel n) earthquakes. The vertical bars indicate the uncertainty of the InSAR-derived ground displacements.