Volcanism as an active planetary process on Venus

Volcanism has been a crucial planetary process in the evolution of Venus, shaping the surface and contributing to the formation of the atmosphere and clouds. Some of the key outstanding questions are whether or not volcanism is active today, and what range of volcanic styles have occurred in the past or may occur in the future. This project uses three methods of investigating these questions. Firstly, computer modelling is used to simulate volcanic processes under Venusian conditions using a steady-state, isothermal, homogeneous flow model. It was found that the addition of CO2 to an H2O-driven eruption reduces the H2O requirement for explosive activity, and that eruptions possible on Venus may be detectable in Venus Express data. Next, radar datasets from both Venus and Earth were investigated with the aim of assessing relationships between differing volcanic deposits on Venus and their likely mode of formation, and using trends in the Earth radar data to inform us of what the Venus observations may be telling us. It was found that, in some cases, regional-scale radar observations may be useful in identifying deposit types, but the data used in the study were insufficient to define a globally applicable deposit identification scheme, pending further study. Finally, mapping and spatial analysis of volcanic features and rifts was performed to evaluate the nature of the interaction of volcanism within the global tectonic environment. Spatial relationships are consistent with aspects of the directional model of Venus' evolution, favouring a shift from globally dispersed, relatively small-scale, volcanism spread randomly across the planetary surface towards a gradually more rift-focused distribution indicative of a corresponding shift in global tectonic regime. These various strands are brought together here in order to contribute to our further understanding of volcanism as a fundamental Venusian planetary process.