10:45 〜 11:00
[PPS05-01] Numerical simulation of lunar seismic wave: Updated scattering structure around Apollo12 landing site from coda fitting approach
★招待講演
キーワード：Moon、Moonquake、Scattering、Apollo、Planetary seismology
The Apollo lunar seismic observation opened a way to investigate the internal structure of the Moon. Using the Apollo seismic data, previous studies (e.g. [1] and references therein) tried to constrain 1D velocity structure mainly through a classical travel time analysis. Generally, in travel time analysis, the determination of seismic phase arrival (e.g. P, S) is a key to a precise estimation of the inner structure. However, while seismic phases can be read with a precision of 0.1 s for earthquakes, it becomes worse by about 1-3 orders in the case of the Moon due to an intense scattering of regolith and/or megaregolith. Since the arrival reading differs from researcher to researcher, the resulting structures fall within a large error, which implies that the lunar internal structure is still uncertain. As the internal structure gives a crucial information for constraining the origin and evolution of the Moon, this problem is placed as one of the most significant issues in lunar science.
In this study, we propose a novel way to constrain the internal structure. The previous studies or classical seismology determines it based on a point information within time-series (to be clear P, S arrival). On the other hand, we attempt to constrain it by conducting numerical simulations under different parameter settings (like P-wave, S-wave model, scattering model) and by fitting the shape of the observed seismic data by Apollo. Although this kind of approach is not a major way in seismology, we found it possible to constrain not only 1D velocity structure but also internal heterogeneity with this method since a seismic wave envelope actually depends on both internal scattering properties and seismic wave velocity profile.
In the presentation, we will show results of the velocity and scattering structure around Apollo12 landing site estimated by modeling Apollo artificial impacts. After that, we will discuss how our results can contribute to future lunar or other planetary seismic explorations.
Reference
[1] Garcia et al., Lunar seismology: An update on interior structure models, Space Sci. Rev., 215 :50, 2019, https://doi.org/10.1007/s11214-019-0613-y.
In this study, we propose a novel way to constrain the internal structure. The previous studies or classical seismology determines it based on a point information within time-series (to be clear P, S arrival). On the other hand, we attempt to constrain it by conducting numerical simulations under different parameter settings (like P-wave, S-wave model, scattering model) and by fitting the shape of the observed seismic data by Apollo. Although this kind of approach is not a major way in seismology, we found it possible to constrain not only 1D velocity structure but also internal heterogeneity with this method since a seismic wave envelope actually depends on both internal scattering properties and seismic wave velocity profile.
In the presentation, we will show results of the velocity and scattering structure around Apollo12 landing site estimated by modeling Apollo artificial impacts. After that, we will discuss how our results can contribute to future lunar or other planetary seismic explorations.
Reference
[1] Garcia et al., Lunar seismology: An update on interior structure models, Space Sci. Rev., 215 :50, 2019, https://doi.org/10.1007/s11214-019-0613-y.