9:30 AM - 9:45 AM
[PPS06-03] Virtual Multichannel Analysis of Surface Waves for Apollo 14 Active Seismic Experiment
Keywords:Moon, Apollo, Surface wave exploration, Seismic interferometry
Imaging the shallow subsurface on the Moon through seismic exploration is important to explore water resources on the polar region, and evaluate the stability of the ground for constructing a lunar base. However, an available seismic equipment such as geophones and seismic sources on the Moon is limited because of their high transportation costs. We therefore developed a method to synthesize virtual multichannel seismic data (i.e., shot gather) from the limited number of geophones and sources of Apollo 14 active seismic experiment data.
Using the shots inside the two geophones, we constructed the shot gather based on seismic interferometry. We then extracted the stable surface wave dispersion curve by applying multichannel analysis of surface waves for noisy Apollo 14 data, reducing noise with continuous wavelet transform (Ikeda and Tsuji, 2019). The S-wave velocity profile at the Apollo 14 landing site was estimated by inversion of the experimental dispersion curve. The S-wave velocity profile demonstrates that the regolith layer has a hard stratum (> 70 m/s) under 3 m depth. In the depth of 3–10 m, the S-wave velocity is ~75–85m/s. The S-wave velocity structure is similar to that at the Apollo 17 landing site from ambient noise analysis by Tanimoto et al. (2008).
This study shows that shallow seismic surveys can be possible with limited resources (source and receivers) and with their inadequate geometry in extraterrestrial environment. Furthermore, seismic exploration using active seismic sources is efficient because it can be conducted in a short period, compared to seismic surveys using ambient noise. Thus, our approach will be useful for future planetary exploration missions.
We used data obtained from Data ARchives and Transmission System (DARTS), provided by Center for Science-satellite Operation and Data Archive (C-SODA) at ISAS/JAXA.
Using the shots inside the two geophones, we constructed the shot gather based on seismic interferometry. We then extracted the stable surface wave dispersion curve by applying multichannel analysis of surface waves for noisy Apollo 14 data, reducing noise with continuous wavelet transform (Ikeda and Tsuji, 2019). The S-wave velocity profile at the Apollo 14 landing site was estimated by inversion of the experimental dispersion curve. The S-wave velocity profile demonstrates that the regolith layer has a hard stratum (> 70 m/s) under 3 m depth. In the depth of 3–10 m, the S-wave velocity is ~75–85m/s. The S-wave velocity structure is similar to that at the Apollo 17 landing site from ambient noise analysis by Tanimoto et al. (2008).
This study shows that shallow seismic surveys can be possible with limited resources (source and receivers) and with their inadequate geometry in extraterrestrial environment. Furthermore, seismic exploration using active seismic sources is efficient because it can be conducted in a short period, compared to seismic surveys using ambient noise. Thus, our approach will be useful for future planetary exploration missions.
We used data obtained from Data ARchives and Transmission System (DARTS), provided by Center for Science-satellite Operation and Data Archive (C-SODA) at ISAS/JAXA.