10:30 AM - 10:45 AM
[S18-1-01] Geodynamical modeling and seismic observations: a step towards mapping regional structures of Earth's inner core
invited
The inner core displays a hemispherical difference in seismic velocity, attenuation, and anisotropy, which is well-established from seismic studies. Recent observations reveal increasingly complex and regional features. However, geodynamical models generally only attempt to explain the basic east-west asymmetry. Regional seismic features, such as depth-dependence anisotropy or variation in hemisphere boundaries, are difficult to reproduce and relatively poorly constrained by seismic data.
There are two major theories to explain the inner core hemispheres. The first invokes lateral translation of the inner core to generate a hemispherical difference in age of inner core material. The second requires a asymmetry between the hemispheres in growth rate of the inner core boundary, whereby the east hemisphere grows faster. Processes to generate the more complicated structures, such as anisotropy, sharp hemisphere boundaries, and regional features, are debated.
Seismic data sampling of the inner core is especially limited in some regions, leading to difficulty interpreting the small-scale features. Here, we present a new trans dimensional tomographic inversion for inner core seismic velocity, that accounts for the influence of uneven data coverage. The model provides improved constraints on regional-scale structure within the hemispheres, as well as lateral variation of the hemisphere boundaries, and estimates of the uncertainty in isotropic and anisotropic velocity. We compare these observations to results from our new, open-source Python code “GrowYourIC". The code simulates growth, translation, and super-rotation of the inner core, with a goal of reproducing the inner core seismic properties, as well as revealing the limitations of inhomogeneous sampling in real datasets.
There are two major theories to explain the inner core hemispheres. The first invokes lateral translation of the inner core to generate a hemispherical difference in age of inner core material. The second requires a asymmetry between the hemispheres in growth rate of the inner core boundary, whereby the east hemisphere grows faster. Processes to generate the more complicated structures, such as anisotropy, sharp hemisphere boundaries, and regional features, are debated.
Seismic data sampling of the inner core is especially limited in some regions, leading to difficulty interpreting the small-scale features. Here, we present a new trans dimensional tomographic inversion for inner core seismic velocity, that accounts for the influence of uneven data coverage. The model provides improved constraints on regional-scale structure within the hemispheres, as well as lateral variation of the hemisphere boundaries, and estimates of the uncertainty in isotropic and anisotropic velocity. We compare these observations to results from our new, open-source Python code “GrowYourIC". The code simulates growth, translation, and super-rotation of the inner core, with a goal of reproducing the inner core seismic properties, as well as revealing the limitations of inhomogeneous sampling in real datasets.