Apollo 17 Lunar Surface Gravimeter as a Seismometer: Relocating Shallow‐Moonquake Sources and Implications for Source Mechanism

Among the reported seismic events on the Moon, shallow moonquakes are known for their unique features, such as high-frequency energy excitation, similarity to intraplate earthquakes, and the largest energy release of all reported moonquakes. Despite these interesting features, a small number of samples (<80 events) and sparse seismic network observations prevented us from gaining an in-depth understanding of shallow moonquakes. In this study, by using the Apollo 17 gravimeter as a pseudo-seismometer, we extend the Apollo lunar seismic network and located a few shallow moonquakes more accurately. In addition, comparing the located shallow-moonquake epicenters with surface/subsurface geological features indicates that at least one event may be better explained by deep-seated faults within the crust. Along with a previous demonstration of low-frequency moonquakes, our analysis of high-frequency events shows that the Apollo 17 gravimeter can serve as a seismometer over a broader frequency range than previously considered.