Topographic variability on Mars: Implications for lava flow modeling

A new data analysis technique is presented for quantifying topographic variability on the surface of Mars directly from Mars Orbiter Laser Altimeter ( MOLA) Precision Experiment Data Record ( PEDR) elevation data. The statistic expressing the degree of variability is the mean standard deviation of the residuals resulting from regressions on MOLA PEDR elevation profiles. This topography statistic is determined for ten volcanic areas on the basis of thousands of data points from 181 PEDRs. The topography statistic varies considerably, exhibiting a strong correlation to volcanic area. Despite the correlation with volcanic area, the correlation between topographic variability and slope is weak. Lava flow thickening behavior is quantified with two statistics that are, in turn, used as a rough measure of rheologic change. There is a strong, significant correlation between both flow thickening statistics and topographic variability. These results suggest that the influence of local topographic variability is more important than previously thought in modeling lava flows on Mars.