May 16, 2018,
noon - 1 p.m.
Earth’s core, the deepest region of our planet, stores heat used for plate tectonics and generates Earth’s magnetic field, yet details of its nature remain uncertain. The composition of the outer core, and the inner core which is slowly crystallizing at the center of the Earth, is not fully known — the core contains roughly a third of the mass of the Earth, yet we do not know which light elements are alloyed with the core’s iron and nickel. The outer core is thought to be well-mixed for the most part, but may contain stratified layers at its boundaries. The slowly growing inner core exhibits seismic heterogeneity at a variety of length-scales. Both short period body-wave data, comprising seismic waves which travel through either the outer core or both the outer and inner core, and long period normal mode frequencies, corresponding to vibrations of the whole Earth, can be used to enhance our understanding of the core. This colloquium will address a variety of the seismological features which are present in the core, from the radially varying velocity and density of the outer core, through to the possibility of “hemispherical” differences in anisotropic texture and smaller scale variation in the inner core.