Shock wave propagation in layered planetary interiors: Revisited
Résumé
While major impacts during late accretion of a Mars type planet occur on a differentiated body, the characteristics of the shockwave propagation are poorly known
within these layered objects. Here, we use iSALE-2D hydrocode simulations to calculate shock pressure in a differentiated Mars type body for impact velocities
ranging from 5 to 20 km/s, impactor radii ranging from 50 to 200 km, and different rheologies. To better represent the distribution of shock pressure as a function of
distance from the impact site at the surface, we propose two distinct regions in the mantle: a near field region that extends to 7–15 times the projectile radius into the
target, where the peak shock pressure decays exponentially with increasing the distance from the impact site, and a far field region where the pressure decays
strongly with the distance following a power law. At the core-mantle boundary, the peak shock pressure increases from the mantle side to the core side. The refracted
shockwave travels within the core where the shock pressure decreases following a second power law. In this study, we fit the output obtained from iSALE hydrocode
simulations to determine scaling laws that illustrate the influence of the distance from the impact site, the ray angle, the target rheology, the impactor size and the
impact velocity. Finally we combine these shock-pressure scaling laws with the formalism proposed by Watters et al. [2009] to determine the impact heating induced
by large impacts within a differentiated Mars
Domaines
Pétrographie
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