Abstract
Through numerical simulations, we investigate impact generated seismic wave transmission in granular media under extremely low pressure. This mimics the conditions in the interior of asteroids and other small planetary bodies. We find a dependency not only on the overburden pressure on the medium, but also on the velocity of the impact that generates the wave. This is, at extremely low values of overburden pressure, the wave speed depends no only on the imposed pressure, but also on the increment in pressure created by the passing of the wave. We study crystalline and random packings and find very similar behaviour though with different wave speeds as expected. We then relate our results to different mission-related events on asteroids.
Highlights
It is known that seismic waves speed in a granular medium is related to the overburden pressure (P)applied to it [1, 2]
The theory that has been developed is called Effective Medium Theory (EMT) and is based on considering the media as elastic, removing the difficulties presented by particle size and shape
We changed the overburden pressure over 5 orders of magnitude and the results were always consistent; as pressure decreases so does the wave speed
Summary
It is known that seismic waves speed in a granular medium is related to the overburden pressure (P). The theory that has been developed is called Effective Medium Theory (EMT) and is based on considering the media as elastic, removing the difficulties presented by particle size and shape. This theory, based on the Hertzian laws for contacts, predicts a sound velocity that has a. S waves are related to the elastic constants of the material, in the long wave limit, these can be written as: vp =. Use a soft-sphere discrete element method (SSDEM) code and relate our findings to different space missions
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