← Back to Sessions

An Initial Map of Scatterers in the Inner Core

Session: Sensors, Seismicity and Imaging [Poster]

Type: Poster

Date: 4/21/2021

Presentation Time: 11:30 AM Pacific

Description: 

The Earth’s inner core (IC) is the youngest, fastest-growing, yet least understood part of the Earth. The IC grows from the solidification of the ironic outer core (OC). The latent heat and light elements are the energy source of the geodynamo, which generates the geomagnetic field.

The IC has been modeled mostly with radial layering and a hemispherical dichotomy in velocity, anisotropy, and attenuation. However, interpretation of these heterogeneous IC features has so far been incomplete and often contradictory. The features have been variously attributed to layering during formation, IC boundary deposition and melting, internal convection, anisotropic texturing, partial melt near the boundary, and perhaps modulated by interactions with the thermal boundary conditions of the overlying mantle.

Here, we applied novel beamforming and back-projection to 1970s data from the dense Large Aperture Seismic Array to build an initial 3D map of upper IC heterogeneity from the IC boundary to 500 km depth. Our model, which covers about 40% of the IC, has two strongly scattering regions, one beneath eastern Asia and the other beneath South America, both located where past local surveys have identified structure. These loci of strong fine-scale heterogeneity may be related to small dimensions and random alignments of IC crystals due to fast freezing. They correspond to areas identified as having high attenuation and lie beneath colder areas of the core-mantle boundary, perhaps providing constraints on the dynamics of the IC and the motions in the outer core.

Presenting Author: Wei Wang

Student Presenter: No

Authors