Internal structure of the Moon inferred from Apollo seismic data and selenodetic data from GRAIL and LLR

The internal structure of the Moon is important for discussions on its origin and evolution. However, the deep structure of the Moon is still debated due to the absence of comprehensive seismic data. This study explores lunar interior models by complementing Apollo seismic travel time data with selenodetic data which have recently been improved by Gravity Recovery and Interior Laboratory (GRAIL) and Lunar Laser Ranging (LLR). The observed data can be explained by models including a deep-seated zone with a low velocity (S wave velocity=2.90.5km/s) and a low viscosity (approximate to 3 x 10(16)Pas). The thickness of this zone above the core-mantle boundary is larger than 170km, showing a negative correlation with the radius of the fluid outer core. The inferred density of the lowermost mantle suggests a high TiO2 content (>11wt.%) which prefers a mantle overturn scenario.