ALBERT

Description: We analyze the shapes of twenty eight hypothesized scoria cones in three regions on Mars, i.e. Ulysses and Hydraotes Colles and Coprates Chasma. Using available HiRISE and CTX Digital Elevation Models, we determine the basic morphometric characteristics of the cones and estimate from ballistic modelling the physical parameters of volcanic eruptions that could have formed them. When compared to terrestrial scoria cones, most of the studied cones show larger volumes (up to 4.2 × 10 9  m 3 ), larger heights (up to 573 m) and smaller average slopes. The average slopes of the Ulysses, Hydraotes and Coprates cones range between 7° and 25°, and the maximum slopes only rarely exceed 30°, which suggests only a minor role of scoria redistribution by avalanching. Ballistic analysis indicates that all cones were formed in a similar way and their shapes are consistent with an ejection velocity about two times larger and a particle size about twenty times smaller than on Earth. Our results support the hypothesis that the investigated edifices were formed by low energy Strombolian volcanic eruptions and hence are equivalent to terrestrial scoria cones. The cones in Hydraotes Colles and Coprates Chasma are on average smaller and steeper than the cones in Ulysses Colles, which is likely due to the difference in topographic elevation and the associated difference in atmospheric pressure. This study provides the expected morphometric characteristics of Martian scoria cones, which can be used to identify landforms consistent with this type of activity elsewhere on Mars and distinguish them from other conical edifices.