GNGTS 2016 - Atti del 35° Convegno Nazionale

GNGTS 2016 S essione 2.1 321 The Thermal Infrared Radiations are measured by satellite techniques. Possible fluctuations on temperature values have been attributed to Radon flowing in the Earth’crust. Physical model exist which put in direct relation (through the ionization processes due to Radon decay) the increasing of Radon emission with near surface temperature variations. However Earth’s Thermally emitted radiation is known to increase also by effect of local greenhouse effects related to abrupt releases of greenhouse gases (like CO 2 , CH 4 , etc.), which are often (like in the case of CO 2 ) earthquake precursors too. The key points of the data analysis is the definition of anomaly and its characteristics (Precursor Time, Amplitude, duration), the estimation of the influence of environmental parameters and how to select predictable earthquakes. Data analysis . In this work the long-term time series of Radon and TIR data collected in Northern Italy will be analysed by applying a RST methodology, implemented on the Radon data. To identify the possible anomalous value a new index based on ALICE index has been computed. The long-term time series of Radon are: 13 years for Cazzaso, 5 years for Prato and 4 years for Novara. The Cazzaso survey site is equipped, at 670 m above the sea level, with a Lucas scintillation cell type (Prassi-Silena), settled with continuous radon recording. The accuracy is of 4 Bq/ m3. The air is inhaled by pumping, from a 40.5-m deep well with a 9-cm diameter, at a 7- m depth. Sampling interval is 3 hours (Riggio et al. , 1999). Unfortunately, the time series is discontinuous because of interruptions due to malfunction and, from 2000 to November 2002, to the closing due to lack of funds. From the tectonic point of view the area contains Alpine and Dinaric structures. Alpine structures are characterized by thrust faults with trends E-W, cut by subvertical faults with N-S direction. The Dinaric structures are often characterized by transcurrent activity. To the west the area is bounded by the Periadriatic fault. The intense tectonic activity is driven by the subduction of the Adria Plate beneath the Alpine- Dinaric belt, whose relative motion causes an intense seismic activity with the occurrence of several destructive earthquakes. The Prato radon in air/soil monitoring site is managed by “Prato Ricerche – Istituto Geofisico Toscano, Prato and by the CAI Section of Prato and consists of a Multiparameter Radon Monitor AlphaGuard by Genitron (ionisation chamber), installed inside the Forra Lucia Cave. The cave is a karst cavity whose entry opens on the mountains of Calvana (Prato) and in which the Rio Buti is flowing. The first dataset is recorded from March to June 2007 with 10- minute sampling interval, the second dataset is from June 2008 to December 2012 with a 1-hour sampling interval. The seismicity of the area is characterized by medium-strong earthquakes in central Italy. The Novara radon in soil monitoring site is managed by the Osservatorio Geofisico di Novara founded in 1980 by volunteers with the support of the Civil Protection Department. The radon in soil survey site is placed into a courtyard of the Town Hall of Novara. The detector is positioned about 1 meter below ground level, protected by a 15 cm diameter plastic tube and wrapped in a polythene bag. The sampling interval is 1 hour and the unit of measurement is the count. The detector is a prototype that analyses the electrical signals generated by radon and discriminates them according to their amplitude. The selected impulses are then collected by a data logger that performs their counting and storage. From the tectonic point of view, the Novara area is characterized by the Cremosina fault. The seismicity of the area is characterized by local events with medium-low magnitude. As discussed in previous papers (e.g. Tramutoli et al., 2015) to identify Significant TIR Anomalies (STA) possibly related to an impending earthquake, the following requirements have to be preliminarily satisfied by candidate pixels: Relative intensity: ⊗ ΔT ( r , t ) ≥ 3.5; Images affected by particular meteorological conditions (e.g. wide cloudy coverage),