Simultaneous observations of radon concentrations in soils and thermal remote sensing dynamics in a seismic active area

The paper deals with the simultaneous observation of two important environmental parameters: Land Surface Temperature (LST) and Radon (Rn) concentration. Both parameters have a consistent literature of observations in seismically active regions, especially in cases in which they are proposed as possible and reliable earthquake precursors. Till today their use is topic of discussion, explicitly related to the basic subject of the effective predictability of seismic activity. Theories also exist that link thermal infrared (TIR) emissions to Radon anomalous degassing considering its radioactive decay the cause of air ionization, water vapour condensing and release of latent heat. The simultaneous observation of two parameters was performed with two very different technologies which are best performing for each single observable: Radon is a heavy and quick to decay noble gas and can be monitored in soil, in water and in air. In this first experiment the air is inhaled by pumping from a well to notice its concentration in soil by radionuclide activity (Bq/m3); Land Surface Temperature is monitored through geostationary multispectral satellite, a technology which allow to perform a continuous and simultaneous survey of wide regions without variations of acquisition geometries and projection angles for each pixel. Geostationary thermal data have been frequently proposed to be the most useful mean to relieve thermal earthquake precursors in spite of their lower spatial resolution than those ones collected by polar satellites. The satellite thermal dynamics monitoring has been carried out by means of a recent processing technique, the Night Thermal Gradient, able to take advantage from the high time resolution of geostationary satellites and reach an important improvement in spatial resolution of maps looking at environmental thermal transients. The simultaneous observation of the two parameters was carried out along a bit more than one year but was heavily influenced by the stability of Radon sensor which went occasionally out of service. However, the first results are encouraging looking at some spikes in Rn time series that show similar timing of NTG spikes, frequently anticipating them. The comparison of the single station Rn monitoring and LST maps is especially interesting and need to be extended to more continuous data sets to confirm the presence of extended thermal anomalies at the time of a Rn spikes even in apparently absence of anomalies in the NTG time series of the only pixel containing the well of the Rn station.