Abstract Understanding the behaviour of fluids in hydrothermal systems is a key factor in volcano monitoring. Measuring gas emissions in volcanic areas is strategic for detecting and interpreting precursory signals of variations in volcanic activity. The role of radon as a potential precursor of earthquakes has been extensively debated. However, radon anomalies appear to be better suited to forecast eruptive episodes as we know the loci of volcanic eruptions and we can follow the evolution of volcanic activity. Radon mapping is an effective tool in assessing diffuse and concentrated degassing at the surface. We hereby summarize the in-soil radon emissions collected worldwide and further discuss a collection of data on our key targets. These are closed-conduit and open-conduit volcanoes: Vesuvius (Italy) and La Soufrière (Guadeloupe, Lesser Antilles), Stromboli (Italy) and Villarrica (Chile), respectively. In all the above volcanoes, faults and fracture systems control radon degassing. Automatic and real-time measurements help us to detect major changes in volcanic activity. We present and discuss the radon time series associated with the last effusive eruption at Stromboli. Spectral analyses reveal diurnal and semi-diurnal cycles being probably modulated by atmospheric variations. Multiple linear regression (MLR) analyses have been performed by filtering the radon signals from the effects of local environmental parameters. The residuals do not show particular variations or precursory peaks as the gases have been released from this open-conduit volcano before the onset of the effusive phase (7 August 2014). It is finally emphasized that radon is not the sole precursor, and we should also rely on other geochemical and geophysical parameters. In this perspective, we propose a methodological procedure that can contribute to improving volcano surveillance in an attempt to mitigate volcanic risk.

Abstract The career of the Austrian-born landscape painter Eugene von Guérard (1811–1901) was defined by his travels, which took him to Italy and Germany in the 1830s and 1840s and to Australia and New Zealand between 1852 and 1882. Today he is recognized as one of Australia’s greatest nineteenth-century landscape painters. His formative years coincided with the emergence of geology as an independent scientific discipline and a growing awareness in the wider community of the role played by volcanic activity and other geological processes in the formation of the Earth’s geomorphology. This new understanding was particularly pertinent to landscape painters, whose very subject was the form of the land; in Germany, where von Guérard trained and worked between 1838 and 1852, its relevance for landscape painters was emphasized by the influential natural scientist Alexander von Humboldt and the scientist, landscape painter and art theorist Carl Gustav Carus. They argued that the artist should paint from a geologically informed perspective. Von Guérard’s interest in volcanic geology was sparked by his experiences in southern Italy, consolidated in Germany on expeditions through the Harz and Eifel regions and then fully realized in response to the landscapes of southeastern Australia. Through his informed portrayal of sites of geological significance in each hemisphere and through the cultural value invested in them as a consequence of his depiction of them, von Guérard epitomized that recently conceived construct: the geotourist.