Deformazioni indotte da flussi idrici sotterranei nel Carso Triestino

Il Carso Classico \ue8 un vasto areale a carso maturo sviluppato in una potente idrostruttura, caratterizzata da intensa e diffusa carsifi cazione anche ben al di sotto del livello del mare. La zona satura \ue8 potente ed estesa con una zona di oscillazione che verso monte raggiunge il centinaio di metri di spessore durante le piene importanti, come risulta dagli strumenti posizionati nell\u2019Abisso di Trebiciano, circa 20 km in linea d\u2019aria dalle sorgenti. Fra l\u2019Abisso di Trebiciano e le foci, a circa 12 km da queste ultime, si apre la Grotta Gigante, all\u2019interno della quale, dal 1960, \ue8 presente una stazione geodetica per la registrazione delle deformazioni crostali. Si analizzano le deformazioni indotte dalle variazioni di livello delle acque di fondo del Carso confrontando i dati geodetici della Grotta Gigante con quelli idrologici dell\u2019Abisso di Trebiciano. Analizzando i dati con campionamento giornaliero, si riconosce una correlazione fra il segnale clinometrico e le piene; i due segnali hanno sfasamento temporale massimo di un giorno. Il segnale clinometrico \ue8 un transiente, per cui il clinometro torna alla posizione iniziale successivamente al passaggio della piena ed ha un\u2019orientazione caratteristica lungo la direttrice N150W-N30E. Il segnale clinometrico \ue8 proporzionale al livello raggiunto nell\u2019Abisso di Trebiciano (100 nrad di inclinazione corrispondono a 9.7 m di incremento di livello). Le piene nell\u2019Abisso di Trebiciano devono superare 23.2 m, per provocare il segnale clinometrico a Grotta Gigante

The On-orbit Calibrations for the Fermi Large Area Telescope

The Large Area Telescope (LAT) on--board the Fermi Gamma ray Space Telescope began its on--orbit operations on June 23, 2008. Calibrations, defined in a generic sense, correspond to synchronization of trigger signals, optimization of delays for latching data, determination of detector thresholds, gains and responses, evaluation of the perimeter of the South Atlantic Anomaly (SAA), measurements of live time, of absolute time, and internal and spacecraft boresight alignments. Here we describe on orbit calibration results obtained using known astrophysical sources, galactic cosmic rays, and charge injection into the front-end electronics of each detector. Instrument response functions will be described in a separate publication. This paper demonstrates the stability of calibrations and describes minor changes observed since launch. These results have been used to calibrate the LAT datasets to be publicly released in August 2009.Comment: 60 pages, 34 figures, submitted to Astroparticle Physic

Karst deformations due to environmental factors: evidences from the horizontal pendulums of Grotta Gigante, Italy

The aim of this work is to characterize the deformation of a natural cave induced by temperature varia-tions and by the underground water flow. We consider the tilt recorded by two horizontal pendulums installed in the largest cave of the Italian Karst, the Grotta Gigante. The environmental factors we consider are temperature, rainfall and level and flow rate of the river Reka that feeds the underground Karstic waters. The tilt and temperature have a regular annual cycle, with period of 365 days, which is caused primarily by the thermo-elastic deformation. Semiannual periods are present but more than 10 times smaller. For rainfall and river level the semi-annual and annual oscillation have comparable am-plitudes. The effect induced by the underground water flow consists in a tilting towards SW, that has a linear relation between maximum tilting and the integrated amount of water entering the Karst during the flood, with tilting coefficient a = 10.7 10-6 nrad/m3. The minimum amount of water giving a tilt signal is V0 = 5.2 106 m3

Detecting the elevated crust to mantle section in the Kohistan-Ladakh Arc, Himalaya, from GOCE observations

The Kohistan Ladakh area in northeastern Pakistan is an exposed top to bottom crustal section, implying that high density rocks of the lower crust are at the surface. The new GOCE satellite observations improve the gravity field in this remote area, giving a new dataset for geophysical interpretation. We use the new data to determine the crustal thickness variations and to define the geometry of the overturned crustal columns constituting the base of the former island arc. For the first time the entire extension of the arc is traced with the help of the gravity field observed by GOCE. The entire arc generates a positive gravity signal up to 180 mGal, limited by two geological boundaries, the Main Karakorum Thrust at north, and the Main Mantle Thrust at south. The Main Karakorum thrustmarks the transition from the Indian to the Eurasian plate. The crustal thickness varies here between 40 and 70 km. The three geologic units that define the Kohistan arc, the South Plutonic Complex, the Chilas and Gilgit Complexes, occupy the upper crust, with depths increasing northwards between 14 and 44 km. There are not enough constraints to model the eastern part of the arc, the Ladakh, but the similarity of the gravity signal suggests that the thickness of the upper dense crustal units is similar

The study of karstic aquifers by geodetic measurements in Friuli Venezia Giulia (North East Italy) for a water sustainable management

East Italy, in particular in the area of the Cansiglio Plateau and the Classical Karst. The tiltmeters are set in natural caves (Bus de la Genziana and Grotta Gigante) making part of two interesting karstic areas of particular hydro \u2013 geologic importance. These areas have high vulnerability. From the Friuli slopes of the karstic massif the Livenza River is born. The Classical Karst hosts the Timavo River aquifer. In the specific case of Cansiglio by means of comparison of the tilt- signal registered at the Genziana station with the pluviometrical series of Cansiglio and the hydrometric series of Livenza, local hydrologic effects have been observed and interpretations have been proposed. Putting in correlation also the GPS data of Caneva, a clear correspondence has been ascertained among the clinometric, satellite geodetic and hydro \u2013 pluvimetrical signals. The slow deformations recorded match the curves of run-off of the karstic aquifer, meanwhile one can observe also brief deformations correlable to conspicuous rain precipitations. We record hydrodynamics signals also by an analysis in the Classical Karst between Grotta Gigante pendulums and the River Timavo discharge. The purpose of research is to open a new multidisciplinary frontier between geodetic studies and studies of the karstic systems to obtain a better indirect knowledge of the underground hydric circulation and thus a more complete geologic description for a water sustainable management

La satzione geofisica ipogea della Grotta Gigante (Carso Triestino) Rapporto annuale 2009

7nonenoneBraitenberg C.; Zadro M.; Nagy I.; Grillo B.; Zidarich S.; Romeo G.; Taccetti Q.Braitenberg, Carla; Zadro, Maria; Nagy, ILDIKO' ERZSEBET; Grillo, Barbara; Zidarich, S.; Romeo, G.; Taccetti, Q

La stazione geofisica ipogea della Grotta Gigante (Carso Triestino) Rapporto annuale 2010

10nonenoneBraitenberg C.; Nagy I.; Grillo B.; Tenze D.; Mariani P.; Zidarich S.; Romeo G.; Taccetti Q.; Spinelli G.; Benedetti P.Braitenberg, Carla; Nagy, ILDIKO' ERZSEBET; Grillo, Barbara; Tenze, Daniele; Mariani, Patrizia; Zidarich, Sergio; Romeo, G.; Taccetti, Q.; Spinelli, G.; Benedetti, P