Crustal structure of the Moon determined from short-period Rayleigh wave analysis

Víctor Corchete^*

• University of Almeria, Almería, Spain

The lunar crustal structure is determined in the depth range from 0 to 40 km, by means of Rayleigh wave analysis. The traces of 3 moonquakes have been used to obtain Rayleigh wave dispersion (group velocities), in the short period range (fundamental mode: 0.5-12.5 s, first mode: 0.5-5.5 s, and second mode: 1-4 s). These moonquakes were registered by two stations emplaced on the Moon during the Apollo program. The dispersion was calculated with a combination of filtering techniques, and later was inverted the fundamental-mode dispersion to obtain an S-velocity model, i.e., an S-velocity distribution with depth. The S-velocity increases with depth, and a rapid S-velocity gradient is observed from 0 to 5 km-depth, while the S-velocity gradient becomes smaller down to 5 km-depth. The present S-velocity model contributes to the lunar crustal structure determination, more work is needed to achieve the precise determination of this structure, which will be possible when higher quality data are acquired in future missions.Plain Language Summary. A rapid S-velocity gradient is determined from 0 to 5 km-depth. The low S-velocities (< 2 km/s) determined for the first layers (0-2 km-depth), can be associated to the presence of broken and fractured materials at the uppermost lunar strata. The S-velocity increases with depth, but the S-velocity gradient becomes slower below 5 km depth.