演講資訊

摘要：

A stabilizing feedback between the atmosphere, hydrosphere, and geosphere is important for long-term habitability (biosphere). Studying planetary interiors can help to better understand a planet as a system, from formation and evolution, to current structure and dynamics (from center to surface). Physical and chemical processes that govern the dynamics of planetary interiors likely occur at many scale lengths. Stratification is a dominant feature of all planetary interiors. Fine-scale structure associated with layering, as well as heterogeneities holds important clues on a planet’s compositional, thermal, and dynamical state. Seismic waves recorded on planetary bodies can help to resolve structures that directly relate to the material properties of the planets, such as seismic discontinuities and seismic anisotropy. Earth and Moon are the (only) two planetary bodies with a certain amount of seismic available data for such analyses. In Earth, seismic anisotropy represents one of the primary mechanisms for probing deformation and melting processes. We deployed the ocean bottom seismographs on ~70 Ma Pacific lithosphere with the aim of constraining the flow dynamics within the oceanic asthenosphere. Our data suggest that the asthenosphere is flowing on its own with smaller scale and seafloor spreading at the ridge produces a very strong lithospheric fabric. The Apollo Passive Seismic Experiment (APSE) consisted of four 3- component seismometers deployed between 1969 and 1972 that continuously recorded lunar ground motion until late 1977. We applied modern array methodologies to the legacy APSE dataset and aimed at detecting deep lunar seismic reflections. Our results suggest the presence of a solid inner and fluid outer core, overlain by a partially molten boundary layer with the lunar core radius ~ 330+-20km. Although the geophysical observations provide the snapshot for the present-day planetary interiors, a better understand of a planetary interior will guide us to know more about the formation and evolution of the habitable planets.