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A strong inner core and squish
It is believed that the inner core of the Earth is solid, which means that it should withstand shear waves. However, the small size of the inner core makes it very difficult to detect shear waves. Tkalčić and Phạm correlated different types of seismic phases to finally determine the speed of shear waves in the Earth's inner core (see Irving Perspective). Wave detection puts an end to 80 years of research and confirms the presence of a strong, yet flexible core.
Science, this number p. 329; see also p. 294
Abstract
Seismic J The waves, the shear waves that pass through the inner core of the Earth, impose direct stresses on the strength and shear properties of the inner core. However, these waves have been elusive in the direct seismic wave field due to their small amplitudes. We have developed a new method to detect J waves in the seismic coda correlation wave field. They are manifested by the similarity with other signals sensitive to the compressive nucleus. The inner core is solid, but relatively soft, with shear velocities and shear moduli of 3.42 ± 0.02 km per second and 149.0 ± 1.6 gigapascals (GPa) near the inner limit of the kernel and 3.58 ± 0.02 km per second and 167.4 ± 1.6 GPa. in the center of the Earth. The values are 2.5% lower than the widely used Earth Preliminary Reference Model. This creates new constraints for the dynamic interpretation of the inner core of the Earth.
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