IGPP is pleased to invite you to join its Fall 2021 Virtual Seminar Series presentation featuring USC's Wei Wang. Dr. Wang's talk, "What can we learn from inner core scattering?" will be available via Zoom on Tuesday, September 28, 2021, starting at 12:00pm.
Date: Tuesday, September 28, 2021
Time: 12:00 pm, Pacific Time
Abstract: Earth’s inner core (IC) is a central but poorly understood frontier for the earth sciences. The seismic structures of the IC, i.e., velocity, attenuation, anisotropy, are the key to understand its growth history, composition, and thermal state. Currently, the structure of the IC is mostly recognized as the degree-one dichotomy. It is still challenging to resolve its small-scale and/or 3D structure due to the limited information brought by the seismic waves and uneven distribution of earthquakes and stations. However, the 3D structure is very important to decipher the IC growth history, thus, to understand the dynamics of the outer core and the formation of the geomagnetism.
In this talk, we will firstly introduce our initial 3D map of heterogeneity from the IC boundary to 500 km depth covering about 40% of the IC surface, which is visible from the Large Aperture Seismic Array in Montana, USA. Our finding is the first seismic evidence that the ICB may be intimately involved in the IC growth via the outer core (OC) dynamics. Second, based on the precise locations of the scatterers within the IC, I will introduce our new and firm measurement of the inner core motions, including both rotation and precession, by studying the time shifts of the compressional seismic waves scattered by the heterogeneities within the IC from a co-sited pair of nuclear tests in Novaya Zemlya, USSR. Investigation on the motion of the IC may improve the knowledge of the formation and evolution of the IC and OC and enhance the understanding Earth’s geomagnetic fields.