地球惑星科学専攻 地球科学輻合部特別講演会
 
講演題名：
Earth's Inner Core as a Conglomerate of Anisotropic Domains
 
講演者：　
Hrvoje Tkalcic
(The Australian National University)
 
日時: 2011年1月17日(月) 16:30〜18:00
場所: 京都大学理学部1号館4階462号室
 
講演概要：
     The days when the Earth’s inner core (IC) was viewed as a homogenous solid body with
a cylindrical anisotropy having a fast axis nearly parallel to the Earth’s rotation axis are
now behind us. A number of concepts for the IC structure and dynamics have been
proposed to explain different types of seismological observations, but due to a lack of an
experimentally controlled environment in the seismology of the deep Earth, it is difficult
to scrutinize competitive hypotheses. In Earth sciences, we often come closer to the truth
through negative instances rather than the verification of existing hypotheses.
     With the current configuration of receivers and large earthquakes worldwide, it is
difficult to achieve a satisfactory sampling of the inner core, except for the paths nearly
parallel to the equatorial plane. I will give an overview of the past research, show recent
observations that increase constraints on the core structure, anisotropy and the nature of
the inner-outer core discontinuity, and discuss some ideas for the future research. From
recent observations and core-sensitive data analysis, I argue that a conglomerate of
anisotropic domains in the IC combined with the inhomogeneous structure of the mantle
is a likely working hypothesis that reconciles observed complexities in differential PKP
travel times while preserving a net IC anisotropy that is required to explain the
anomalous splitting of Earth's free oscillations. I also present arguments for an inevitable
trade-off role of the mantle in conjunction with the interpretation of IC structure.
 
問い合わせ先：
久家慶子