Estimation of the Rate of Slope Processes and Morphological Variability of Kilometer-Sized Impact Craters on the Moon

In order to estimate the rate of slope processes on the Moon, we studied the morphology and topographic configuration of 24 craters in the diameter range of 5–15 km. These craters are located in Mare Serenitatis, Mare Crisium, and Mare Fecunditatis, as well as in the continental terrain of Montes Apenninus. The craters were formed in three types of targets: (1) two-layered (continent, overlaid by a mare), (2) single-layered mare, and (3) single-layered continent. The topographic configuration was established for each crater, and the frequency–size distribution of overlapping craters on the walls and in the continuous ejecta zone was determined. The age of the craters was estimated (from 0.31 to 3.83 Gyr) based on the crater density in the ejecta zone. Comparing this density with the density on the walls allowed us to estimate the rate of slope processes. The rate of slope processes (E, mm/Myr) on the Moon is nonlinear and described by a power-law function Е = 4.39А^–1.03, where А is the age (Gyr). The estimated rates of slope processes in our study range from ~17 mm/Myr for the youngest crater to ~0.8 mm/Myr for the oldest crater. The studied craters represent stable landforms, and their configuration remains almost unchanged over billions of years. The target type has no significant influence on either the rate of slope processes or the changes in crater shape over time.