Modeling impact cratering in layered surfaces

Abstract

[1] Impact craters are potentially powerful tools for probing large-scale structure beneath planetary surfaces. However, the details of how target structure affects the impact cratering process and final crater forms remain poorly understood. Here, we present a study of cratering in layered surfaces using numerical simulations. We implement the rheologic model for geologic materials described by Collins et al. (2004) into the shock physics code CTH; this model includes pressure, temperature, and damage effects on strength as well the option to include acoustic fluidization. The model produces reasonable final crater shapes and damaged zones from laboratory to planetary scales. We show the effects of varying material strength parameters and discuss choosing appropriate strength parameters for laboratory and planetary situations. Results for cratering into idealized terrains with layers of differing material strength are presented. The presence of such layers in the target can significantly alter the ejecta curtain structure and the final crater morphology. Finally, we reproduce the morphologic variations that are observed in small lunar craters by modeling a weak regolith overlying competent rock.

Could Pantheon Fossae be the result of the Apollodorus crater-forming impact within the Caloris basin, Mercury?

“…There are, however, a variety of impact damage studies upon which we can draw size estimates. Senft and Stewart (2007) used a shock physics code to reproduce final crater shapes and damage zones from laboratory to planetary scales. They found that the depth to the base of the damage zone is~1/4 the final crater diameter, a result in qualitative agreement with data from terrestrial craters (Ahrens et al, 2001).…”

Dynamic cratering of graphite: Experimental results and simulations

“…In case of a hypervelocity impact of a small steel sphere onto a target, the main damage is due to tensile and shear strength. Senft and Stewart [8] compared results from simulations with both tensile and shear damage as well as with tensile damage only. It showed tensile loading is mainly responsible for the damaging process.…”

“…Metals have been widely studied, both experimentally [6] and through the use of numerical hydrocodes [7]. Some brittle materials have also been included in HVI studies, such as geophysical materials [8], and silica glass that covers solar arrays or can be used as transparent windows [9]. Experiments and hydrodynamic simulations have emphasized their difference with ductile metals [10].…”

Three‐dimensional joint inversion of traveltime and gravity data across the Chicxulub impact crater

“…A second seismic experiment carried out in 2005 improved the resolution of these seismic models significantly and allowed better constraints on the crater asymmetries and the central uplift [Vermeesch and Morgan, 2008]. Numerical models for the formation of large complex impact craters and multiring basins all show an upward movement within the center of the crater during collapse [e.g., Grieve et al, 1981;Collins et al, 2002;Wünnemann et al, 2005;Senft and Stewart, 2007]. When excavation has ceased, the uplifted rim collapses inward and downward to form a terrace zone, and the uplifted central zone collapses downward and outward to form a peak ring [e.g., Collins et al, 2002].…”