![]() However, in response to the lack of detected impacts in the first year of InSight's operations, the number of expected impacts has been revised to approximately three detectable impact events per Earth year, with a large uncertainty on that estimate (I. The number of impact events detected by the InSight's seismometer was originally expected to be about a dozen (I. On Mars, it is expected that only small, meter-to-decameter size, craters will form during lifetime of the InSight mission, considering the impact statistics and a given distance from the lander (I. There are several possible causes of seismicity on Mars, including thermal and lithostatic stresses caused by daily changes in temperature on this planet, recent volcanic activity (Knapmeyer-Endrun et al., 2017), and meteoroid impacts (I. 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. The numerical simulation results showed that the seismic efficiency spans 2 orders of magnitude, for the investigated crater size range and target analog for the Martian bedrock and regolith. Our results show that the pressure wave behaves differently in different target properties. In this work, we are using the iSALE-2D (Impact-Simplified Arbitrary Lagrangian Eulerian) shock physics code to simulate meter-size crater formation on Mars. Having estimates for the values of the seismic efficiency in such events can help in further describing the properties of the Martian surface, particularly if impact conditions are known. Seismic efficiency describes how much of the impact's kinetic energy is transferred into seismic energy. The impactor's kinetic energy is spent on internal energy change (heating), plastic (irreversible) and elastic (reversible) deformation in the target. When impact occurs, it releases shock waves into the target medium. Impact cratering is a common geological process on solid planetary bodies. For new impacts occurring on Mars, this work can help understand the near-surface properties of the Martian crust, and it contributes to the understanding of impact detectability via seismic signals as a function of the target media. We constrained the value of the impact-related seismic efficiency to be between the order of ∼10 - 7 to 10 - 6 for the regolith and ∼10 - 4 to 10 - 3 for the bedrock. We used appropriate strength and porosity models defined in previous works, and we identified that the seismic efficiency is very sensitive to the speed of sound and elastic threshold in the target medium. ![]() ![]() ![]() ![]() The Martian crust was simulated as unfractured nonporous bedrock, fractured bedrock with 25% porosity, and highly porous regolith with 44% and 65% porosity. We used the iSALE-2D (Impact-Simplified Arbitrary Lagrangian Eulerian) shock physics code to simulate the formation of the meter-size impact craters, and we used a recently formed 1.5 m diameter crater as a case study. This work investigated the seismic efficiency of the Martian near surface associated with small meteorite impacts on Mars. Detectability of impact generated seismic signals is closely related to the seismic efficiency, defined as the fraction of the impactor's kinetic energy transferred into the seismic energy in a target medium. It gives us an opportunity to investigate the seismicity of Mars, including any seismic activity caused by small meteorite bombardment. The first seismometer operating on the surface of another planet was deployed by the NASA InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission to Mars. ![]()
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