Seismo Lab Seminar

Probing the Earth's inner core (IC), which accounts for just about 1% of the Earth's volume, is critical for understanding the planet's formation and evolution. However, geophysical inferences have been challenging due to the lack of seismological probes sensitive to the IC, including its shear properties. Interestingly, the late records several hours after the earthquake's origin, namely the earthquake coda, can be cross-correlated to manifest the similarity between feeble arrivals to become a new, powerful class of seismological observations that are sensitive to the Earth's deep interior. This development gives rise to an emerging concept of "coda correlation wavefield." In this talk, I will demonstrate the use of the correlation wavefield in putting new constraints on Earth's deep interior, particularly the inner core. The main findings include the confirmation of the inner core's solidity via robust detections of shear waves (J-waves) and further evidence for the innermost inner core with unprecedented ricocheting waves up to five times along the Earth's diameters. The seismic insights are expected to shed light on the chemical compositions, physical states, and dynamics of the Earth's deepest shell.