Seismic Efficiency for Simple Crater Formation in the Martian Top Crust Analog

Abstract

Since the successful landing of the NASA InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission to Mars and the deployment of the Seismic Experiment for Interior Structure (SEIS) instrument (Banerdt et al., 2020; Lognonné et al., 2020), there is an opportunity to investigate the Martian interior in greater detail using seismology. There are several possible causes of seismicity on Mars, including thermal and lithostatic stresses caused by daily changes in temperature on this planet,

Numerical Simulations of the Apollo S‐IVB Artificial Impacts on the Moon

“…Cases 6 and 7, are both same porous sphere projectiles, impacting two different targets, pure regolith and a layered target, and between them seismic efficiency has increased ∼2 times. This suggests that while seismic efficiency does depend on target properties (Rajšić et al, 2021), it is relatively insensitive to impactor properties, such as geometry and density. Although, seismic efficiency between porous cylindrical projectiles (Cases 1 and 2) and projectile that included void (Case 3) was similar, in Table 4 we also show the duration of the isolated pressure pulse and its amplitude.…”

“…This results in total seven different scenarios explored in this study. These target properties were used in previous simulations of small meteoroid impacts on similar targets on Mars (Rajšić et al, 2021;.…”

“…Density of the fractured bedrock was ρ = 2,150 kg•m −3 . Bulk speed of sound of the material (C b ) and P-wave speed (C p ) were 1,558 ms −1 and 2,045 ms −1 , respectively (Rajšić et al, 2021). Material models for projectile and all targets are shown in Table 2.…”

“…Referring to previous works, the transient crater was considered at the maximum excavation volume (Wünnemann et al, 2011). Figure 3 (Liu et al, 2017;Rajšić et al, 2021; The calculations of seismic efficiency and seismic moment required tracking the decay of the impact-induced pressure wave into the elastic regime, which occurs in the far field (here defined as radial distance 𝐴𝐴 ≥ 10 crater radii). As shown in previous work (Rajšić et al, 2021;Wójcicka, Collins, Bastow, Miljkovic, et al, 2020), the pressure wave can be considered elastic when pressure amplitudes become comparable with the cohesion of the target material (Table 2) (e.g., Holsapple, 1993).…”

“…To calculate seismic efficiency k, we used the same approach as in many previous works (e.g., Güldemeister & Wünnemann, 2017;Rajšić et al, 2021;Wójcicka, Collins, Bastow, Miljkovic, et al, 2020): k = πx 2 P 2 Δt/ (ρC p E k ), where, x is the distance from the impact point, P is the pressure amplitude, Δt is the duration of the pressure pulse measured at full width half maximum, ρ is the bulk density of the target, and E k is the kinetic energy of the impactor. In case of the double-layered target, bulk density and P wave velocity were assumed to be as in lower layer (fractured bedrock).…”