Fig. 1: Observed temporal changes of seismic data sampling the Earth’s lowermost mantle between doublet AI-0009 at seismic station IU.SDV.
From: Decadal change of seismic structure in the Earth’s lowermost mantle
a Superimposed IU.SDV waveforms between doublet AI-0009 (red for event 2000 and blue for event 2009) after the correction for the effect of the relative doublet location and origin time, with the radial and transverse components labeled as R comp. and T comp. respectively, and the temporally changing SKS and S-Scd-ScS phases noted. b Ray paths of SKS (left panel) and S-Scd-ScS (right panel) from doublet AI-0009 (star) to station IU.SDV (triangle), along with associated temporally changing ultra-low velocity zone (ULVZ; orange) and the lowermost mantle (D″; green). The inner core boundary and the core-mantle boundary are labeled as ICB and CMB, respectively. c Superimposed SKS and S-Scd-ScS waveforms in zoom-in time windows marked by dashed lines in panel a. Note the waveform and travel time changes of SKS phases and the travel time shift in the radial component of S-Scd-ScS phases but no travel time change in the transverse component. Waveforms are bandpass filtered from 0.4 Hz to 2.0 Hz.
