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Geographical variations of the 0S0 normal mode amplitude: predictions and observations after the Sumatra-Andaman earthquake
Earth, Planets and Space volume 59, pages 307–311 (2007)
The radial seismic normal mode 0S0 was strongly excited by the 2004 Mw = 9.3 Sumatra-Andaman earthquake at a period of 20.5 min. In a spherically symmetric Earth model, 0S0 amplitude is the same everywhere on the Earth’s surface. However, when the ellipticity and rotation of the Earth are taken into consideration, theoretical computations predict an amplitude of 0S0 1% higher at the pole than at the equator. Based on a realistic three-dimensional heterogeneous rotating elliptic Earth model, our predictions indicate that the amplitude of 0S0 is 2% higher at the pole than at the equator. A longitude dependency of 0S0 amplitude is also shown. The analysis of 13 superconducting gravimeter (SG) records of the 2004 Sumatra-Andaman earthquake supports the predicted geographical variations of 0S0 amplitude. We have also obtained new estimates for the frequency and Q of 0S0: 0.8146566±1.6 10−6 mHz and 5506±19.
Amalvict, M., H. McQueen, and R. Govind, Absolute Gravity Measurements and Calibration of SG-CT031 at Canberra, 1999–2000, J. Geodetic Soc. Jpn., 47(1), 410–416, 2001.
Banka, D. and D. J. Crossley, Noise levels of superconducting gravimeters at seismic frequencies, Geophys. J. Int., 139, 87–97, 1999.
Buland, R., J. Berger, and F. Gilbert, Observations from the IDA network of attenuation and splitting during a recent earthquake, Nature, 277, 358–362, 1979.
Crossley, D., J. Hinderer, G. Casula, O. Francis, H.-T. Hsu, Y. Imanishi, G. Jentzsch, J. Kaarianen, J. Merriam, B. Meurers, J. Neumeyer, B. Richter, K. Shibuya, T. Sato, and T. van Dam, Network of superconducting gravimeters benefits a number of disciplines, EOS, 80, 121–126, 1999.
Dahlen, F. A., The effect of data windows on the estimation of free oscillations parameters, Geophys. J. R. Astron. Soc., 69, 537–549, 1982.
Dahlen, F. A. and J. Tromp, Theoretical Global Seismology, Princeton: Princeton University Press., Princeton, N.J., 1025 pp, 1998.
Davis, P., IRIS/IDA DCC report, DMS Standing Committee, web link: http://ida.ucsd.edu/pdf/GSNSC_2005_03.pdf2005.
Deuss, A. and J. H. Woodhouse, Theoretical free-oscillation spectra: the importance of wide band coupling, Geophys. J. Int., 146, 833–842, 2001.
Dziewonski, A. M. and D. L. Anderson, Preliminary Reference Earth Model, Phys. Earth Planet. Int., 25, 297–356, 1981.
Dziewonski, A. M., X.-F. Liu, and W.-J. Su, Lateral heterogeneity in the lowermost mantle, in Earth’s Deep Interior, edited by D. J. Crossley, (Cordon and Breach, Newark, N.J.), 11–49, 1997.
Hinderer, J., N. Florsch, J. Mäkinen, H. Legros, and J. E. Faller, On the calibration of the superconducting gravimeter using absolute gravity measurements, Geophys. J. Int., 106, 491–497, 1991.
Ishii, M. and J. Tromp, Normal-Mode and Free-Air Gravity Constraints on Lateral Variations in Velocity and Density of Earth’s Mantle, Science, 285, 1231–6, 1999.
Ishii, M. and J. Tromp, Even-degree lateral variations in the Earth’s mantle constrained by free oscillations and the free-air gravity anomaly, Geophys. J. Int., 145, 77–96, 2001.
Knopoff, L., W. Zürn, P. A. Rydelek, and T. Yogi, Q of mode 0S0, J. of Geophys., 46(2), 89–95, 1979.
Nawa, K., N. Suda, K. Satake, T. Sato, K. Doi, M. Kanao, and K. Shibuya, Loading and gravitational effects of the 2004 Indian Ocean tsunami observed at Syowa Station, Antarctica, BSSA, 2006 (submitted).
Peterson, J., Observations and modelling of seismic background noise, Open-File Report 93–332, U.S. Department of Interior, Geological Survey, Albuquerque, New Mexico, 1993.
Resovsky, J. S. and M. H. Ritzwoller, New and refined constraints on the three-dimensional Earth structure from normal modes below 3 mHz, J. Geophys. Res., 103(B1), 783–810, 1998.
Riedesel, M. A., D. Agnew, J. Berger, and F. Gibert, Stacking for the frequencies and Qs of 0S0 and 1S0, Geophys. J. Roy. Astron. Soc., 62, 457–471, 1980.
Rosat, S., J. Hinderer, and L. Rivera, First observation of 2S1 and study of the splitting of the football mode 0S2, Geophys. Res. Lett., 30, 21,2111, 2003.
Rosat, S., J. Hinderer, D. Crossley, and J. P. Boy, Performance of superconducting gravimeters from long-period seismology to tides, J. Geodyn., 38(3-5), 461–476, 2004.
Rosat, S., T. Sato, Y. Imanishi, J. Hinderer, Y. Tamura, H. McQueen, and M. Ohashi, High resolution analysis of the gravest seismic normal modes after the 2004 Mw=9 Sumatra earthquake using superconducting gravimeter data, Geophys. Res. Lett., 32, L13304, doi:10.1029/2005GL023128, 2005.
Roult, G. and Clévédé, E., New refinements in attenuation measurements from free-oscillation and surface-wave observations, Phys. Earth Planet. Int., 121, 1–37, 2000.
Roult, G., S. Rosat, R. Millot-Langet, E. Clévédé, and J. Hinderer, New determinations of Q quality factors and eigenfrequencies for the whole set of singlets of the Earth’s normal modes 0S0, 0S2, 0S3 and 2S1 using SG data from the GGP network, J. Geodyn., 41, 345–357, 2006.
Sato, T., Y. Tamura, K. Matsumoto, Y. Imanishi, and H. McQueen, Parameters of the fluid core resonance inferred from superconducting gravimeter data, J. Geodyn., 38, 375–389, 2004.
Sato, T., J.-P. Boy, Y. Tamura, K. Matsumoto, K. Asari, H.-P. Plag, and O. Francis, Gravity tide and seasonal gravity variations at Ny-Alesund, Svalbard in Arctic, J. Geodyn., 41, 234–241, 2006.
Su, W.- J., R. L. Woodward, and A. M. Dziewonski, Degree-12 model of shear velocity heterogeneity in the mantle, J. Geophys. Res., 99, 6945–6980, 1994.
Tamura, Y., T. Sato, Y. Fukuda, and T. Higashi, Scale factor calibration of a superconducting gravimeter at Esashi Station, Japan, using absolute gravity measurements, J. Geodesy, 78, 481–488, 2005.
Van Camp, M., Measuring seismic normal modes with the GWR C021 superconducting gravimeter, Phys. Earth Planet. Int., 116, 81–92, 1999.
Watada, S., H. Kanamori, and D. L. Anderson, An analysis of Nearfield normal mode amplitude anomalies of the Landers earthquake, Geophys. Res. Lett., 20(23), 2611–2614, 1993.
Widmer-Schnidrig, R., What can superconducting gravimeters contribute to normal mode seismology?, Bull. Seism. Soc. Am., 93(3), 1370–1380, 2003.
Woodhouse, J. H., The coupling and attenuation of nearly resonant multi-plets in the Earth’s free oscillation spectrum, Geophys. J. Roy. Astron. Soc., 61, 261–283, 1980.
Woodhouse, J. H. and A. M. Dziewonski, Mapping the upper mantle: three dimensional modelling of Earth structure by inversion of seismic waveforms, J. Geophys. Res., 89, 5953–5986, 1984.
Zürn, W. and R. Widmer, On noise reduction in vertical seismic records below 2 mHz using local barometric pressure, Geophys. Res. Lett., 22, 3537–3540, 1995.
Zürn, W., L. Knopoff, and P. A. Rydelek, High precision measurement of the frequency of mode 0S0, J. Geophys., 48(3), 158–160, 1980.
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Rosat, S., Watada, S. & Sato, T. Geographical variations of the 0S0 normal mode amplitude: predictions and observations after the Sumatra-Andaman earthquake. Earth Planet Sp 59, 307–311 (2007). https://doi.org/10.1186/BF03353109
- Seismic radial mode 0S0
- superconducting gravimeter
- Sumatra-Andaman earthquake
- lateral heterogeneities