HR: 0800h
AN: S41C-1004    [Abstracts]
TI: Body Wave Constraints on Inner Core Shear Wave Attenuation
AU: * Cao, A
EM: acao@seismo.berkeley.edu
AF: Berkeley Seismo Lab UC Berkeley, 215 McCone Hall UC Berkeley, Berkeley, CA 94720 United States
AU: Romanowicz, B
EM: barbara@seismo.berkeley.edu
AF: Berkeley Seismo Lab UC Berkeley, 215 McCone Hall UC Berkeley, Berkeley, CA 94720 United States
AB: Based on the high quality broadband data from Grafenberg array in Germany, we recently detected a reliable PKJKP phase, for which four kinds of evidence (travel time, slowness, back-azimuth, and comparison with a pseudo-liquid inner core model) were simultaneously provided. Also, for the first time, a clear waveform of PKJKP was observed. This gives us an unprecedented opportunity to put constraints on the shear wave attenuation in the earth's inner core using body waves. In order to minimize the potential influence of dispersion and phase shift caused by mantle heterogeneity, we adopt an envelope modeling approach. Our results show that the estimated Q_β from shear body wave PKJKP is significantly larger than that from normal mode observations. Qβ is well constrained to be larger than ~ 150 (compared to 85 for the reference PREM model) and our best estimate is Q_β ~ 315± 150. Because PKJKP samples the deep inner core, whereas the PREM estimate is based on normal mode data which have sensitivity primarily to the top of the inner core, this indicates an increase of Q_β with depth in the inner core, in agreement with what is generally observed for Q_β.
DE: 7203 Body waves
DE: 7207 Core (1212, 1213, 8124)
SC: Seismology [S]
MN: Fall Meeting 2005