Adaptation of a Thermorheological Lava Flow Model for Venus Conditions

Active volcanism was (and potentially still is) an important process that shapes the Venus surface and its detection is a primary goal for the planned VERITAS and EnVision missions. Therefore, understanding lava flow emplacement and timing on Venus is important. We adapt the terrestrial PyFLOWGO thermorheological model to Venus conditions to assess the effects on channelized lava flow propagation. We first initiate the model with terrestrial basaltic parameters and progressively adapt it to Venusian conditions in five steps: (a) gravity, (b) ambient atmospheric temperature, (c) specific heat capacity and wind speed, (d) atmospheric density, and (e) coupled convective and radiative heat flux. Compared to Earth, the slightly lower gravity on Venus resulted in a lower flow velocity, a higher crust coverage, and a very minor increase in flow length (0.1%). Increasing the ambient atmospheric temperature reduced heat loss and produced a (77%) longer flow; whereas next accounting for the atmospheric specific heat capacity and wind speed increased the flow length slightly more (81%). However, increasing the atmospheric density resulted in a shorter lava flow (13%) due to more efficient cooling. Finally, accounting for coupled convective and radiative heat loss due to the strong CO2 infrared absorption resulted in an increase of the flow length (similar to 75%). Although the model applies only to channelized, cooling-limited flows, these results reveal that for the same effective effusion rate and topography, a Venusian lava flow travels a longer distance than the equivalent flow on Earth and its cooling should be detectable by future orbital instruments. Plain Language Summary Lava flow length and velocity is partially controlled by the environmental conditions of a planet (e.g., gravity, atmospheric temperature, and density). Observations reveal that Venus volcanism is an important process that shaped its surface. However, the extreme surface environment influences the emplacement of these lava flows differently than on Earth. In this study, we quantify the impact of the Venusian planetary and environmental conditions on lava flow advance using the PyFLOWGO model. Although this model is one-dimensional and applies only to channelized, cooling-limited flows, it is exceedingly adaptable, and by far is the most cited model in the literature. Here, we adapt an Earth lava flow to Venus conditions in five steps: (a) gravity, (b) atmospheric temperature, (c) atmospheric specific heat capacity and wind speed, (d) atmospheric density, and (e) coupling atmospheric convective and radiative heat flux. Compared to Earth conditions, the lava flow is most affected by the heat flux difference caused by the CO2-rich Venusian atmosphere, which results in a 75% longer flow than the same flow on Earth due to the decrease in heat loss to the atmosphere. Results for a 100 km Venusian lava flow indicate that it would be observable by the upcoming missions.