Centroid migration on an impacted granular slope due to asymmetric ejecta deposition and landsliding

Abstract

ABSTRACT For a fundamental understanding of terrain relaxation occurring on sloped surfaces of terrestrial bodies, we analyse the crater shape produced by an impact on an inclined granular (dry-sand) layer. Owing to asymmetric ejecta deposition followed by landsliding, the slope of the impacted inclined surface can be relaxed. Using the experimental results of a solid projectile impact on an inclined dry-sand layer, we measure the distance of centroid migration induced by asymmetric cratering. We find that the centroid migration distance xmig normalized to the crater minor-axis diameter Dcy can be expressed as a function of the initial inclination of the target tan θ, the effective friction coefficient μ, and two parameters K and c that characterize the asymmetric ejecta deposition and oblique impact effect: xmig/Dcy = K tan θ/[1 − (tan θ/μ)2] + c, where K = 0.6, μ = 0.8, and c = −0.1 to 0.3. This result is consistent with a previous study that considered the effect of asymmetric ejecta deposition. The obtained results provide fundamental information for analysing the degradation of sloped terrain on planetary surfaces, such as crater-shape degradation due to the accumulation of micro-impacts.