GNGTS 2019 - Atti del 38° Convegno Nazionale

226 GNGTS 2019 S essione 1.4 Remarkably, we found the middle and the lower crust to be rather homogeneous, bearing no sign of the Miocene volcanism. At greater depths, an inhomogeneous seismic structure suggests a heterogeneous lithospheric mantle. Interestingly, the lateral variations we observe would be consistent with the hypothesis of a Mediterranean plume-like body, sustained by several authors on geochemical arguments. The high absolute velocities characterizing the crust, together with the temperatures we estimated, induce us to rule out this idea, even though a larger-scale geophysical study would be needed in order to resolve such deep structure and unravel its nature. The absolute values of the VS also allow us to directly constrain the depth of the LAB (that we locate at ~100 km). We find our estimate consistent with a continental geotherm based on a surface heat flow of 60 mW/m 2 . Our results suggest that most of the lithosphere endured the complex history of deformation experienced by the study area, and imply, in general, that deep tectonic processes do not easily destabilize the deeper portion of the continental lithosphere, despite leaving a clear surface signature. THE MULTIPARAMETRIC STUDY OF THE PREPARATION PHASE OF AN EARTHQUAKE: THE ITALIAN CASE STUDY OF AMATRICE - NORCIA 2016-2017 SEISMIC SEQUENCE D. Marchetti 1,2 , A De Santis 1 1 Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy 2 School of Remote Sensing and Geomatics Engineering, Nanjing University of Information Science and Technology, Nanjing, China Introduction. The object of this work is to look for possible perturbation of the geosystemic system before the occurrence of an earthquake. The possibility that an earthquake could perturb the Geosystem before its occurrence has been theorised for example by Freund, 2011; 2013 and Pulinets and Ouzunov, 2011. The Italian territory is characterized by many seismogenic areas and Central Italy has been affected in the last decades by some important seismic sequences: Colfiorito 1997, L’Aquila 2009 and Amatrice-Norcia 2016-2017, with the towns or cities mainly affected. All the corresponding mainshocks caused many victims and significant damages to buildings and important artistic cultural heritage. Despite there are no reliable methods to predict a seismic event, it is unlikely that such energetic phenomena on Earth surface do not provide some precursors and/or alterations in the environment before their occurrence. The three main events had a moment magnitude of 6.0 (Colfiorito 26-09-1997 09:40:26 UT), 6.3 (L’Aquila 06-04- 2009 01:32:40 UT) and 6.0 (Amatrice 24-08-2016 01:36:32 UT) that released energy of about 6.31 10 13 J, 1.78 10 14 J and 6.31 10 13 J respectively. In the seismic sequence of 2016-2017 a greater event happened on 30-10-2016 at 06:40:17 UT of moment magnitude 6.5 with an approximated energy release of 3.55 10 14 J. It is essential to dispose of multi-parametric instrumentation both on ground and satellite, as the theorised effects that could happen before the occurrence of an earthquake involve various observables, such as physical, chemical and atmospheric characteristics, as well as electric and magnetic alterations both in Earth’s surface and in ionosphere. As in the last years more instrumentation and observations have been available, multiparametric analysis of the recent seismic event has become possible. In particular, for the seismic sequence started on 24 August 2016 with M6.0 earthquake happened at 1:36 UT and still ongoing, many analyses have been carried out. The goal of this work is to show and compare the different results and finally compare them with the possible physical models.