Details

Autor(en) / Beteiligte

• Onodera, Keisuke
• Kawamura, Taichi
• Tanaka, Satoshi
• Ishihara, Yoshiaki
• Maeda, Takuto

Titel

Quantitative Evaluation of the Lunar Seismic Scattering and Comparison Between the Earth, Mars, and the Moon

Ist Teil von

• Journal of geophysical research. Planets, 2022-12, Vol.127 (12), p.n/a

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2022

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• The intense seismic scattering seen in Apollo lunar seismic data is one of the most characteristic features, making the seismic signals much different from those observed on the Earth. The scattering is considered to be attributed to subsurface heterogeneity. While the heterogeneous structure of the Moon reflects the past geological activities and evolution processes from the formation, the detailed description remains an open issue. Here, we present a new model of the subsurface heterogeneity within the upper lunar crust derived through a full 3D seismic wave propagation simulation. Our simulation successfully reproduced the Apollo seismic observations, leading to a significant update of the scattering properties of the Moon. The results showed that the scattering intensity of the Moon is about 10 times higher than that of the heterogeneous region on the Earth. The quantified scattering parameters could give us a constraint on the surface evolution process of the Moon and enable the comparative study for answering a fundamental question of why the seismological features are different on various planetary bodies. Plain Language Summary In the past Apollo missions, several seismometers were installed on the nearside of the Moon and they brought us the first seismic records from an extraterrestrial body. The derived lunar seismic data surprised us because of their extremely long duration (1–2 hr) and spindle‐shaped form, which were barely observed on Earth. These characteristics, which are different from earthquakes, are thought to reflect the subsurface heterogeneity. However, the inhomogeneous structure within the lunar crust is poorly constrained. To improve our knowledge of wave propagation on an extraterrestrial body, this study evaluated the subsurface heterogeneity through 3D seismic wave propagation simulation. After running some simulations under various structure settings, we found that a certain set of parameters well reproduced the Apollo seismic data, resulting in a new heterogeneous structure model of the Moon. The evaluated parameters were compared with those measured on the Earth and Mars, and we found that the Moon is more heterogeneous than others by about 10 times. This kind of comparison makes it easier to interpret the observed seismic signals on each solid body. Also, it is useful to explain the differences in their surface evolution scenarios. We believe that our results contribute to further extending comparative planetology. Key Points Through full 3D seismic wave propagation simulation, we quantitatively evaluated the lunar seismic scattering properties We found that a 10‐km thick scattering layer with 10% velocity fluctuation well‐reproduced the Apollo seismic observation Our results show that the upper lunar crust is about 10 times more heterogeneous than that of the Earth and Mars