GNGTS 2021 - Atti del 39° Convegno Nazionale

GNGTS 2021 S essione 1.1 68 soil category – Italian Seismic Code, NTC 2018; Iervolino et al ., 2018) under the installation point of the various recording stations. We get PGA horizontal (north and east) and vertical compo- nents from the ITACA dataset covering seismic events affecting Italy. 3. Results We calculated the area affected by the most severe deformation inferred from InSAR coseis- mic ground deformation data, excluding the surrounding zones where the motion is lower than one single interferometric fringe. We analyzed images from the three main tectonic settings, i.e., extensional, contractional and strike-slip available in the literature (Fig. 1). Events span in the pe- riod ranging between 1993 and 2020 plus one event in 1980. The coseismic ground deformation illuminated by InSAR data is not surrounding the epicenter in a circular pattern, but it is rather regularly elliptical in normal and thrust tectonic settings or quadrilobated in strike-slip earth- quakes, being elongated, parallel and adjacent to the activated fault system. The maps depict- ing the coseismic fringes (or measured deformation) for the 32 selected earthquakes were then used to calculate the area of the surface affected by deformation during the coseismic phase. We consider areas interested by subsidence (or negative LOS when only single orbit data is avail- able) , uplift (or positive LOS when only single orbit data is available) and both of them for nor- mal, thrust and strike-slip faults respectively. In Fig. 2 we show the comparison between these values and the recorded magnitudes. All the events clearly show that deformed areas increase by increasing the magnitudes (Petricca et al ., 2021). The plots highlight the different trends as a function of the earthquake mechanisms since thrust and normal fault earthquakes have a gentler curvature than strike-slip ones. Taking Mw 6.5 as reference magnitude, the elongated fingerprint Fig. 2 - Earthquake magnitude versus deformed area in the different tectonic settings. List of earthquakes in Table 1. The area (that represents at least the 90% of the mobilized rocks) affected by vertical (or LOS) movement increases with magnitude and appears to be larger for strike slip faults for a given magnitude.