Deep lunar interior inferred from recent seismic data

Analysis of recent lunar seismic data from distant meteoroid impacts, high-frequency teleseismic events and deep moonquakes shows several significant deviations of P- and S-wave travel times from those expected if the lunar interior were homogeneous below the crust. These data are interpreted resulting in a lunar model consisting of at least four and possibly five distinguishable zones: (I) the 50 to 60 km thick crust characterized by seismic velocities appropriate for plagioclase-rich materials, (II) the 250 km thick upper mantle characterized by seismic velocities consistent with an olivine-pyroxene composition, (III) the 500 km thick middle mantle characterized by a high (0.33 - 0.36) Poisson's ratio, (IV) the lower mantle characterized by high shear-wave attenuation and possibly (V) a core of radius between 170 and 360 km characterized by a greatly reduced compressional wave velocity.