Intricate heterogeneous structures of the top 300 km of the Earth's inner core inferred from global array data: II. Frequency dependence of inner core attenuation and its implication

摘要: Abstract We apply a nonlinear waveform inversion method that we developed previously ( Iritani et al., 2010 , 2014 ) to broadband 0.02 – 2 Hz core phase data recorded by global seismic arrays in order investigate the frequency dependence of inner attenuation. The results show prominent difference attenuation between eastern hemisphere and western hemisphere: while is dependent hemisphere, not so hemisphere. Moreover, stronger observed beneath Africa compared North America. This intricate quasi-hemispherical property attenuation, together with variability velocity strength at around 1 reported earlier, can be consistently understood terms relative location observation band absorption peaks are different for regions. peak may reflect iron grain size core: larger than America, it gradually increases depth. However, caution should taken this inference as physical mechanism still poorly constrained both theoretically observationally.