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ID 13931
JaLCDOI
Sort Key
4
タイトル(別表記)
Inversion of normal mode frequencies for estimation of lateral heterogeneity of the earth's elasticity atructure: A numerical test
フルテキストURL
著者
大西 星司 岡山大学大学院理学研究科
小田 仁 岡山大学理学部地球科学科
抄録
An investigation was made on effect of lateral heterogenity of the earth's elasticity structure on the normal mode frequencies. The lateral heterogeneity is expressed by an expansion of spherical harmonic functions, Pιm(cosθ)sinmΦ and Pιm(cosθ)cosmΦ, up to the second order harmonics (ι≤2). Free oscillation freguencies of the heterogeneous earth were computed by the xyz algorithm. Further we derived an analytic expression of partial derivatives of eigenfrequency with respect to the expansion coefficients, and performed a numerical test to verify whether or not it is possible to estimate the heterogeneity of the earth's structure by the inversion of noemal mode frequencies. When the earth is assumed to be elastically isotropic spheroid with short polar and long equatorial radii, frequency spectra affected by longitudinal heterogeneity terms, Pιm(cosθ)(sinmΦ, cosmΦ) (m≠ 0), for given values of ι and m coincide with each other, because these two terms describe the same heterogeneity when the earth is rotated by π/2m around rotation axis. In such a case, we cannot determine accurately the expansion coefficients of tha two heterogeneity terms by inversion of normal mode frequencies, whereas the coefficients of the latitudinal heterogeneity Pι0(cosθ) can be precisely determined. Therefore it is difficult to estimate of lateral heterogeneity of the earth's elasticity structure by the inversion of normal mode frequencies.
キーワード
Normal Mode
Inversion
Earth's Structure
Lateral Heterogeneity
出版物タイトル
Okayama University Earth Science Report
発行日
1996-09-20
3巻
1号
出版者
岡山大学理学部地球科学教室
出版者(別表記)
Department of Earth Sciences Faculty of Science, Okayama University
開始ページ
33
終了ページ
42
ISSN
1340-7414
NCID
AN10506284
資料タイプ
紀要論文
OAI-PMH Set
岡山大学
言語
Japanese
著作権者
岡山大学地球科学研究報告編集委員会
論文のバージョン
publisher
NAID
Eprints Journal Name
esr