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

Abstract 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.