GNGTS 2016 - Atti del 35° Convegno Nazionale

GNGTS 2016 S essione A matrice 25 repeatability of the daily estimates of the coordinates, and the presence of systematic signals. Table 1 presents the coseismic displacements for 22 sites within 100 km of the epicentral area, for which we have reliably detected coordinate changes, in the sense that the coordinate change is larger than one standard deviation. Tab. 1 – Location of 22 permanent GNSS sites and estimated coseismic displacement. The uncertainty is 0.5 mm horizontal and 0.8 mm vertical. E Long (deg) N Lat (deg) Δ East (m) Δ North (m) Δ Up (m) Site ID 13.2924 42.6265 -0.007 0.025 -0.045 AMAT 13.3743 42.3659 0.000 0.001 -0.001 AQRA 13.3502 42.3682 -0.001 0.000 -0.001 AQUI 13.5930 42.8573 0.016 0.007 0.000 ASCC 13.0667 43.1445 0.000 0.003 -0.001 CAM3 12.9818 41.9491 0.002 0.000 0.000 CERT 12.9046 43.0050 0.002 0.001 -0.002 CESI 13.3932 42.4117 0.001 0.001 0.000 CONI 12.6988 42.9549 0.000 0.001 0.001 FOL1 13.3764 43.1206 0.003 0.003 0.002 GINE 13.5198 42.5837 0.007 0.002 0.002 GNAL 12.5775 43.3510 0.002 0.002 -0.001 GUB2 13.3352 43.0628 0.001 0.001 -0.002 GUMA 13.0402 42.6028 -0.020 -0.015 0.001 LNSS 13.2143 42.5088 -0.004 -0.009 0.000 MTER 13.2400 42.5278 -0.005 -0.009 0.001 MTRA 12.9927 42.4555 -0.004 -0.005 0.001 MTTO 13.4656 42.3623 0.000 0.002 0.001 PAGA 12.8533 42.4032 -0.002 -0.003 -0.001 RIET 13.3372 42.3320 -0.001 0.001 -0.001 ROPI 13.7004 42.6621 0.007 0.001 0.001 TERA 12.6495 42.5670 -0.001 0.000 -0.002 TERI Modeling the coseismic surface deformation. We have used the coseismic coordinate changes to assess three hypocentral locations and fault plane solutions available at the Global CMT web page (http://www.globalcmt.org/ ) (Dzienowski et al. , 1981, Ekström et al. , 2012), at the GFZ Geofon webpage (http://www.gfz-potsdam.de/) and at the INGV (http://cnt.rm.ingv . it/tdmt ). The strike of the fault plane has been assumed SE, without loss of generality. We have used the software Coulomb 3.4 (Toda et al., 2005) to generate synthetic surface displacements, based upon the fault plane solutions of the two events of Aug. 24, 2016 given in Tab. 2. The rms of the fit to the horizontal and vertical data reported in the last two columns suggests that the solution of INGV best fits the data. In Fig. 3 we summarize the results of the modeling. The figures on the left compare observed horizontal (top left) and vertical (bottom left) displacements of the GNSS sites with the values predicted on the basis of models defined by the entries in Tab. 2. The computed displacements refer to the cumulative effects of the two earthquakes of August 24, although the one taking place at 2:33 is likely to have resulted in very small surface perturbations. The plots on the right describe the observed and best fitting model displacements in plane (top right) and vertical (bottom right). This last figure should give an idea of the kind of pattern of line-of-sight displacements expected in InSAR data.