HR: 16:30h
AN: DI24A-03    [Abstracts]
TI: Temporal Change of the Earth's Inner Core Property: Observations and Interpretations
AU: * Wen, L
EM: Lianxing.Wen@sunysb.edu
AF: Stony Brook University, Dept. of Geosciences, Stony Brook, NY 11794, United States
AU: Yu, W
EM: yu@mantle.geo.sunysb.edu
AF: Stony Brook University, Dept. of Geosciences, Stony Brook, NY 11794, United States
AB: Recent seismic observations from earthquake waveform doublets provided compelling evidence that the seismic waves associated with the Earth's inner core experience temporal change. In this presentation, we present seismic observations associated with the inner core phases from waveform doublets occurring in the South Sandwich Islands and the Tonga-Kermadec subduction zone, and discuss possible interpretations to the seismic observations. The PKiKP phases recorded for a doublet (1993/2003) occurring in the South Sandwich Islands and reflected off the inner core boundary beneath mid-Africa arrived about 30 to 70 milliseconds earlier for the 2003 event than for the 1993 event, while no temporal change of travel time is observed for the PKiKP phases sampling the inner core boundary beneath South America, the Atlantic Ocean, and the Indian Ocean. The PKIKP and PKiKP phases for waveform doublets occurring in the Tonga-Kermadec subduction zone, with the re- occurrence time greater than eight years and sampling the inner core beneath the Philippine Sea, China, central Asia, the Arctic Ocean, the Indian Ocean, Antarctica, and Alaska, exhibited no temporal change in travel time and waveform. The observed temporal changes of travel time for the PKiKP phases sampling the mid-Africa indicate that the Earth's inner core surface locally enlarged by 1 – 1.75 km between the occurrence of the 1993/2003 doublet. We discuss in detail possible interpretations to the observed/non-observed temporal changes of these core phases, including inner core differential rotation with the presence of irregular topography at the inner core boundary, and rapid localized growth of the inner core due to convection in the top of the inner core or solidification of the outer core.
UR: http://geophysics.geo.sunysb.edu/wen/
DE: 1507 Core processes (1213, 8115)
DE: 7203 Body waves
DE: 7207 Core (1212, 1213, 8124)
DE: 8115 Core processes (1213, 1507)
DE: 8124 Earth's interior: composition and state (1212, 7207, 7208, 8105)
SC: Study of the Earth's Deep Interior [DI]
MN: 2007 Fall Meeting