Physics of Earth’s Interior

Physics of the Earth's Interior aims at understanding the inner workings of the Earth: its internal structure, composition, dynamics, and evolution from the lithosphere to the Earth’s core. It is one of the core and most active research areas in solid earth geophysics with global impacts. Various means are used in this endeavor, including physics, applied math, seismology, gravity, geomagnetism, mineral physics, geodynamics, geodesy, and computational science. As a result, it is a highly inter-disciplinary study and attracts interest from different backgrounds and training. Understanding the Earth also provides a launching pad for exploring other planets. Interested faculty includes:

 

Song, Xiaodong


  Mainly interested in structure and dynamics of the Earth’s interior, especially on the core and the lowermost mantle as well as structure and tectonics of China and East Asia. Studies rely mainly on seismological and other geophysical observations and methods.

 

Using seismic waves, Prof. Xiaodong Song and Paul Richard’s group found (Song and Richards 1996 Nature) and confirmed (Zhang-Song et al. 2005 Science) evidence for the super-rotation of the Earth’s inner core.

 

  Seismological research played a primary role in the initial discoveries of the major layers of the Earth’s interior, from the Earth’s core to the Moho. The basic principle is that when a seismic wave encounters a sharp boundary, the wavefield changes rapidly (with such phenomena as reflections, refractions, and diffractions), which allows us to characterize the properties of the boundary. In modern seismology, wave propagation is more commonly used to reveal the fine details of the three-dimensional structure of the Earth’s interior. Even though the departure of the 3D structure from the 1D layered earth is often less than a few percent (in seismic velocity and in medium density), such departure is fundamental because such heterogeneity is what drives the Earth’s internal dynamics and the plate tectonics at the surface. Fundamental discoveries about the Earth’s interior continue to be made. For example, the accumulation of seismic data makes it possible to monitor the temporal changes deep down in the Earth’s inner core. Using seismic waves, Prof. Song and co-league Paul Richards first detected wave-speed changes through the inner core, which was interpreted as evidence for the super-rotation of the Earth’s inner core. The discovery helps gaining insights of the dynamics of the Earth’s core, which was named as one of the Breakthrough of the Year by Science magazine and one of the most important discovery in the 20th century by DISVOVER magazine. Major progress in observations, methods, and computational power over the last few decades offers great opportunities for new breakthroughs in the studies of the physics of the Earth’s interior.