Buland R, Berger J, Gilbert F. Observations from the IDA network of attenuation and splitting during a recent earthquake. Nature, 1979, 277(5695): 358-362.
[2]
Chao B F, Gilbert F. Autoregressive estimation of complex eigenfrequencies in low frequency seismic spectra. Geophys. J. Int., 1980, 63(3): 641-657.
[3]
Masters G, Gilbert F. Structure of the inner core inferred from observations of its spheroidal shear modes. Geophys. Res. Lett., 1981, 8(6): 569-571.
[4]
Smylie D E. The inner core translational triplet and the density near Earth''s center. Science, 1992, 255(5052): 1678-1682.
[5]
Crossley D J, Rochester M G, Peng Z R. Slichter modes and Love numbers. Geophys. Res. Lett., 1992, 19(16): 1679-1682.
[6]
Guo J Y, Dierks O, Neumeyer J, et al. A search for the Slichter modes in superconducting gravimeter records using a new method. Geophys. J. Int., 2007, 168(2): 507-517.
[7]
Rosat S, Hinderer J, Rivera L. First observation of 2S1 and study of the splitting of the football mode 0S2 after the June 2001 Peru earthquake of magnitude 8.4. Geophys. Res. Lett., 2003, 30(21): 10-11.
[8]
Giardini D, Li X D, Woodhouse J H. Splitting functions of long-period normal modes of the earth. J. Geophys. Res., 1988, 93(B11): 13716-13742.
[9]
Widmer R, Masters G, Gilbert F. Observably split multiplets-data analysis and interpretation in terms of large-scale aspherical structure. Geophys. J. Int., 1992, 111(3): 559-576.
[10]
Masters G, Laske G, Gilbert F. Matrix autoregressive analysis of free-oscillation coupling and splitting. Geophys. J. Int., 2000, 143(2): 478-489.
[11]
Deuss A, Ritsema J, van Heijst H. Splitting function measurements for Earth''s longest period normal modes using recent large earthquakes. Geophys. Res. Lett., 2011, 38: L04303, doi: 10.1029/2010GL046115.
[12]
Masters G, Gilbert F. Attenuation in the earth at low frequencies. Phil. Trans. R. Soc. A, 1983, 308(1504): 479-522.
[13]
Resovsky J S, Ritzwoller M H. New and refined constrains on three-dimensional Earth structure from normal modes below 3 mHz. J. Geophys. Res., 1998, 103(B1): 783-810.
[14]
Shen W B, Wu B. A case study of detecting the triplet of 3S1 using superconducting gravimeter records with an alternative data preprocessing technique. Ann. Geophys., 2012, 55(2): 293-300.
[15]
Huang N E, Shen Z, Long S R, et al. The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis. Proc. Roy. Soc. A, 1998, 454(1971): 903-995.
[16]
Oppenheim A V, Schafer R W, Buck J R. Discrete-Time Signal Processing. 2nd ed. New Jersey: Prentice-Hall, 1999: 693-774.
[17]
He X, Tromp J. Normal-mode constraints on the structure of the Earth. J. Geophys. Res., 1996, 110(B9): 20053-20082.
[18]
Ritzwoller M, Masters G, Gilbert F. Observations of anomalous splitting and their interpretation in terms of aspherical structure. J. Geophys. Res., 1986, 91(B10): 10203-10228.
[19]
Park J, Song T A, Tromp J, et al. Earth''s free oscillations excited by the 26 December 2004 Sumatra-Andaman earthquake. Science, 2005, 308(5725): 1139 -1144.
[20]
Rosat S, Rogister Y, Crossley D, et al. A search for the Slichter triplet with superconducting gravimeters: Impact of the density jump at the inner core boundary. J. Geodyn., 2006, 41(1-3): 296-306.
[21]
Hinderer J, Crossley D. Scientific achievements from the first phase (1997—2003) of the global geodynamics project using a worldwide network of superconducting gravimeters. J. Geodyn., 2004, 38(3-5): 237-262.
[22]
Hinderer J, Crossley J, Warburton R J. Gravimetric methods superconducting gravity meters.//Schubert G. Treatise on Geophysics. Amsterdam: Elsevier, 2007, 3: 65-112.
[23]
Guo J Y, Dierks O, Neumeyer J, et al. Weighting algorithms to stack superconducting gravimeter data for the potential detection of the Slichter modes. J. Geodyn., 2006, 41(1-3): 326-333.
[24]
Hu X G, Liu L T, Hinderer J, et al. Wavelet filter analysis of atmospheric pressure effects in the long-period seismic mode band. Phys. Earth Planet. Int., 2006, 154(1): 70-84.
[25]
Roult G, Roch J, Clévédé E. Observation of split modes from the 26th December 2004 Sumatra-Andaman mega-event. Phys. Earth Planet. Int., 2010, 179(1-2): 45-59.
[26]
Deuss A, Woodhouse J H. Theoretical free-oscillation spectra: the importance of wide band coupling. Geophys. J. Int., 2001, 146(3): 833-842.
[27]
Deuss A, Woodhouse H J. Iteration method to determine the eigenvalues and eigenvectors of a target multiplet including full mode coupling. Geophys. J. Int., 2004, 159(1): 326-332.
[28]
Widmer-Schnidrig R. What can superconducting gravimeters contribute to normal mode seismology? Bull. Seism. Soc. Am., 2003, 93(3): 1370-1380.
[29]
Lei X E, Sun H P, Hsu H T, et al. Check of Earth''s free oscillations excited by Sumatra-Andaman large earthquake and discussions on the anisotropy of inner core. Sci. China Ser. D-Earth Sci., 2007, 50(6): 909-917.
[30]
Lei X E, Sun H P, Hsu H T. Detection and interpretation of the Earth''s free oscillations excited by the great Sumatra-Andaman earthquake with GGP station data. Earthq. Sci., 2011, 24(2): 151-162.
[31]
Dahlen F A. The effect of data windows on the estimation of free oscillations parameters. Geophys. J. R. Astron. Soc., 1982, 69(2): 537-549.
[32]
Okal E A, Stein S. Observations of ultra-long period normal modes from the 2004 Sumatra-Andaman earthquake. Phys. Earth Planet. Int., 2009, 175(1-2): 53-62.
[33]
Courtier N, Ducarme B, Goodkind J, et al. Global superconducting gravimeter observations and the search for the translational modes of the inner core. Phys. Earth Planet. Int., 2000, 117(1-4): 3-20.
[34]
Slichter L B. The fundamental free mode of the Earth''s inner core. Proc. Nat. Acad. Sci., 1961, 47(2): 186-190.
[35]
Sun H, Xu J, Ducarme B. Detect the Earth''s solid inner core translational oscillations based on the international superconducting gravimeter observations. Chinese Science Bulletin, 2004, 49(8): 803-813.
[36]
徐建桥, 孙和平, 傅容珊. 利用全球超导重力仪数据检测长周期核模. 地球物理学报, 2005, 48(1): 69-77. Xu J Q, Sun H P, Fu R S. Detection of long-period core modes by using the data from global superconducting gravimeters. Chinese J. Geophys. (in Chinese), 2005, 48(1): 69-77.
[37]
Cummins P, Wahr J M, Agnew D C, et al. Constraining core undertones using stacked IDA gravity records. Geophys. J. Int., 1991, 106(1): 189-198.
[38]
Gilbert F. The diagonal sum rule and averaged eigenfrequencies. Geophys. J. R. Astron. Soc., 1971, 23(1): 119-123.
[39]
Gilbert F, Dziewonski A M. An application of normal mode theory to the retrieval of structural parameters and source mechanisms from seismic spectra. Phil. Trans. R. Soc., A, 1975, 278(1280): 187-269.
