MODELING A VOLCANIC ERUPTION COLUMN ON MARS : A 4 D SOLUTION

Introduction and background: Current models for explosive volcanic eruptions on Mars are thought to overestimate the maximum sustainable plume height by tens of kilometers [1], a consequence of the simplifying assumptions behind their 1D formulations. Since an actual volcanic eruption on Mars has not been observed, the exact extent of disparity between true and modeled rise heights remains unclear. This has potentially significant impacts on the distribution of Martian primary tephra deposits. Buoyant Martian volcanic plume models [e.g., 2-6] are based on a 1D entrainment hypothesis, which states that the mixing velocity of the ambient atmosphere in a buoyant plume is proportional to its vertical velocity [7]. The underlying assumptions that govern this entrainment hypothesis are invalid when a plume rises or expands radially faster than the speed of sound, the plume expands radially faster than it rises, or if the plume is much wider than it is high [1]; these limitations inherent in the 1D models are likely to result in overestimation of plume height [1]. The maximum plume height produced by an explosive volcanic eruption on Mars has implications for not only interpreting surface deposits, but also on the evolution of the Martian climate. We present results of a new 4D, Navier-Stokes based Martian eruption simulation created by adapting the terrestrial Active Tracer Highresolution Atmospheric Model (ATHAM) [8,9]. These results can then be applied to atmospheric mixing and particulate dispersal [e.g., 10] during eruptions at suggested regions of explosive volcanism on Mars (Fig. 1).