Self‐Similar Initial Morphology of Lunar Simple Craters With Implications for Formation and Degradation Process.
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| Title: | Self‐Similar Initial Morphology of Lunar Simple Craters With Implications for Formation and Degradation Process. |
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| Authors: | Li, Huacheng1 (AUTHOR), Yue, Zongyu1 (AUTHOR) yuezy@mail.iggcas.ac.cn |
| Source: | Journal of Geophysical Research. Planets. May2026, Vol. 131 Issue 5, p1-15. 15p. |
| Subject Terms: | Impact craters, Computer simulation, Moon, Lunar craters, Planetary surfaces |
| Abstract: | Impact craters dominate the lunar surface and morphology‐based dating typically assumes that their initial profiles correspond to the average shape of fresh craters. However, the selected fresh craters may have experienced degradation, and their relationships with impact conditions remain poorly understood. In this study, we present 1,349 numerical simulations of simple crater formations across a wide range of impact conditions (impact velocities of 6–20 km/s and projectile radii of 100–1,000 m). The results show that shapes of simple craters (<15 km in diameter) are self‐similar when described by dimensionless coordinates (normalized by crater radius and depth); however, the depth‐to‐diameter ratio is not constant, revealing a key deviation from the simplification assumed in previous studies. Instead, the depth‐to‐diameter ratio fluctuates within defined, size‐dependent bounds (e.g., 0.290D−0.103 $0.290{D}^{-0.103}$ to 0.306D−0.069 $0.306{D}^{-0.069}$ for above impact conditions). We further find that the derived crater diameters are consistent with π‐scaling laws established from laboratory sand experiments, and the crater depths and volumes are notably underestimated by these scaling laws. Additionally, the inherent variations in initial crater morphology due to varied impact conditions introduce an uncertainty of approximately ±17% when estimating ages based on crater morphology degradation. Our results also indicate that if the average crater profile derived from these numerical simulations is used as the initial profile, the resulting crater ages differ by 28% from those obtained using observed profiles of fresh craters. These findings provide crucial guidance for refining techniques to estimate crater ages from their degradation state, thereby offering critical constraints on planetary surface geological processes. Plain Language Summary: Impact craters on the Moon record its impact history and help scientists understand how planetary surfaces evolve. Estimating crater ages often relies on assumptions about their initial shapes, typically based on measurements of fresh craters. However, such craters are rare and may have changed over millions of years. In this study, we performed over 1,300 numerical simulations to examine how different impact conditions influence initial crater shapes. We found that, although simple craters exhibit a consistent normalized profile, their depth‐to‐diameter ratios show a condition‐dependent variability within defined bounds rather than remaining constant. These variations cause about ±17% uncertainty in age estimates, and using observed fresh crater shapes as the assumed initial profile can lead to ∼28% error due to their degradation. Our results highlight that current methods for dating craters may carry substantial uncertainties. By better characterizing the natural variability in initial crater shapes, this work provides improved guidance for reconstructing the Moon's impact history and offers insights into the evolution of planetary surfaces. Key Points: Simple crater depth‐to‐diameter ratios are not constant but fluctuate within defined bounds based on impact conditionsNumerical simulations confirm that π‐scaling laws are broadly applicable although they may underestimate the final crater depth and volumeUsing observational rather than simulated initial crater profiles causes a ∼28% discrepancy in morphology‐based age estimates [ABSTRACT FROM AUTHOR] |
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| Database: | GreenFILE |
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