HR: 17:30h
AN: DI24A-07    [Abstracts]
TI: PKiKP Coda Observations Interpreted in Terms of the Earth's Inner Core Heterogeneities
AU: * Krasnoshchekov, D
EM: krasnd@idg.chph.ras.ru
AF: Institute of Dynamics of Geospheres, Leninsky pr. 38, korp. 1, Moscow, 119334, Russian Federation
AU: Kaazik, P
EM: kaazik@mail.ru
AF: Institute of Dynamics of Geospheres, Leninsky pr. 38, korp. 1, Moscow, 119334, Russian Federation
AU: Ovtchinnikov, V
EM: ovtch@idg.chph.ras.ru
AF: Institute of Dynamics of Geospheres, Leninsky pr. 38, korp. 1, Moscow, 119334, Russian Federation
AB: Although resulting from gradual few billion years long crystallization process, Earth's inner core (IC) is rather heterogeneous than a single crystal of iron. IC fabric variations such as changes in crystallographic alignment or supposed increase in crystal size with depth often constitute physical grounds for hypothesizing IC heterogeneities of various scale lengths. To constrain upper IC heterogeneities, we analyze reflections from the Earth's inner core boundary and the coda waves following the reflections (PKiKP) on array records of underground nuclear explosions. In particular, we compare PKiKP codas observed after reflections with close bounce points on the surface of the IC and diverse ray paths in the Earth's crust, mantle and outer core. Such PKiKP coda doublets show similar shape, frequency content, intensity and duration, and feature powerful arrivals originating from IC heterogeneities. The proposed interpretation favors misaligned anisotropic iron crystals up to 10 km in size to cause the observed PKiKP codas rather than classical scattering on inclusions in the outermost IC. Also, the IC fabric's image observed as PKiKP coda appears to be time stationary in 20 years span, failing to exhibit any pronounced effect of IC differential rotation.
DE: 7203 Body waves
DE: 7207 Core (1212, 1213, 8124)
SC: Study of the Earth's Deep Interior [DI]
MN: 2007 Fall Meeting