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Eulilli, Valeria
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- PublicationOpen AccessGeodynamic implications of new geodetic measurements in the Messina Straits Area(2001)
; ; ; ; ; ; ; ; ; ; ; ; ;Achilli, V.; DAUR - Università di Padova - Padova - Italy ;Anzidei, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Baldi, P.; Dipartimento di Fisica - Università di Bologna - Italy ;Bonci, L.; Servizio Geologico Nazionale - Roma - Italia ;Bonini, C.; DISTART, Universita’ di Bologna ;Capone, G.; DISTART - University of Bologna - Bologna - Italy ;Casula, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Cesi, C.; Servizio Geologico Nazionale - Roma - Italia ;Eulilli, V.; Servizio Geologico Nazionale - Roma - Italia ;Gandolfi, S.; DISTART - Università di Bologna - Bologna - Italia ;Riguzzi, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Zanutta, A.; DISTART - Università di Bologna - Bologna - Italia; ; ; ; ; ; ; ; ; ; ; Th Messina Straits (southern Italy) on December 28, 1908 was struck by a Ms=7.5, seismic event, that was the largest earthquake occurred in Italy during the last 100 years. The earthquake and the related tsunami caused thousands of victims and severe destruction in a wide area along the Sicilian and Calabrian coasts. After that time many geophysical and geological studies were developed to evaluate the seismic characteristics of the 1908 earthquake, the seismic risk and the geological evolution of the region in the framework of the Mediterranean geodynamics, characterized by the collision between the African and Eurasian plates. With the aim to evaluate the present crustal motion of this area, that undergone a recent tectonic evolution that produced an important uplift during the last 125 Kyears, since 1970 was started a geodetic research. A geodetic network was set up across the Straits and repeatedly measured with terrestrial techniques till 1980. In 1987, a 7 vertices network (4 vertices in common with the already existent network) was surveyed for the first time by the GPS space technique, improving the accuracy of the coordinate determinations. Finally, in 1994 a wider network was established and surveyed again to collect additional GPS observations about a larger area across the Straits. In this paper we provide a general geophysical description of the Area and the results obtained by the analysis of two GPS surveys (1987 and 1994) with respect to those achieved by the terrestrial surveys (from 1970 to 1980). Our analysis leads to exclude the occurrence of significant crustal horizontal deformations across the Straits in ha last 15 years; this conclusion is in agreement with current geophysical models that exclude any aseismic deformations acting in this area.214 103 - PublicationOpen AccessGravity changes in the Aquila area before and after earthquake events(2011)
; ; ; ; ; ; ; In 1989 a joint work was developed in co-operation with the University"Sapienza"of Rome and Servizio Geologico d'Italia (SGI) (today ISPRA). A gravity research started in the Aquila area aimed to realize a gravity network for high precise gravity measurements to detect gravity changes due to mass redistribution in the underground inferred by the geodynamic activity. The gravity network has been designed so as to incorporate 17 stations, settled in 1989 and periodically reoccupied in 1990, 1992, 1995, 2005 and 2011. The local gravity network coincides with some benchmarkes of the local leveling networks (L126, L197, L124 and L9) [Giuliani & Mattone, 2010] in order to remove the effect of the vertical ground movements and taking into account the spatial distribution of seismic events. High precision gravity combined with levelling benchmarks offers increasing potentialities for the study of time variations of the earth gravity field and crustal deformations related with geodynamic or tectonic processes. Presently, the network consists of 17 relative stations which are not destroyed during the earthquake. Gravity readings were made using two LaCoste & Romberg D model gravimeters (D-60 and D-138) at the same time. Presently, and similar to previous studies the new gravity data set has been referred to the Absolute gravity station established in 1977 at the Osservatorio Astronomico di Monte Porzio Catone [Cannizzo et al., 1978]. The gravity readings, for both gravimeters, are corrected for tidal effects, atmospheric loading and instrument drift. Later, as regard the gravity survey, the corrected and weighted gravity differences between each pair of stations are organized on joined loops and then adjusted according to the least square method; finally the gravity value at any station is computed relative to the local reference station (Fonte Cerreto-Assergi (4) station) and linked to the absolute gravity station. During the time period covered by this study, six precise relative gravity surveys were also carried out at all stations of the network. Long-term spatial distribution of gravity changes performed before and repeated after earthquake is represented. Gravity changes have been observed on the whole area, before and after the earthquake period. The gravity distribution shows different patterns in the eastern, central and western part of the seismic area. The gravity variation field is smoother in the central part of L'Aquila city and it shows a gravity decrease from the stations located in the northen part of the city. Qualitative gravity results are not totally in agreement with vertical changes measured by local leveling networks. It is possible to suppose that the observed gravity changes should indicate a mass variation in the underground, not in the shallow part but in depth. Moreover, the results obtained from high precision gravity measurements show that, the most significant long-term observed gravity changes on Aquila area, were recorded not in the area corrisponding to the seismogenic belt but in a largest zone. However gravity changes were observed in the same magnitude before and after the earthquake.85 37 - PublicationRestrictedImplicazioni geodinamiche delle recenti misure geodetiche nello Stretto di Messina(2001)
; ; ; ; ; ; ; ; ; ; ; ; ;Achilli, V. ;Anzidei, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Baldi, P. ;Bonci, L. ;Bonini, C. ;Capone, G. ;Casula, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Cesi, C. ;Eulilli, V. ;Galdolfi, S. ;Riguzzi, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Zanutta, A. ;; ; ; ; ;; ; ; ;; Il 28 dicembre 1908 lo Stretto di Messina veniva colpito da un disastroso evento sismico di ms=7.5. L'evento è il più forte tra i terremoti italiani degli utimi 100 anni.178 22