Seismic excitation of the polar motion, 1977–1993
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The mass redistribution in the earth as a result of an earthquake faulting changes the earth's inertia tensor, and hence its rotation. Using the complete formulae developed byChao andGross (1987) based on the normal mode theory, we calculated the earthquake-induced polar motion excitation for the largest 11,015 earthquakes that occurred during 1977.0–1993.6. The seismic excitations in this period are found to be two orders of magnitude below the detection threshold even with today's high precision earth rotation measurements. However, it was calculated that an earthquake of only one tenth the size of the great 1960 Chile event, if happened today, could be comfortably detected in polar motion observations. Furthermore, collectively these seismic excitations have a strong statistical tendency to nudge the pole towards ∼140°E, away from the actually observed polar drift direction. This non-random behavior, similarly found in other earthquake-induced changes in earth rotation and low-degree gravitational field byChao andGross (1987), manifests some geodynamic behavior yet to be explored.
- Chao, B. F. (1984),On Excitation of Earth's Free Wobble and Reference Frames. Geophys. J. Roy. Astron. Soc.79, 555–563.
- Chao, B. F., andGross, R. S. (1987),Changes in the Earth's Rotation and Low-degree Gravitational Field Induced by Earthquakes, Geophys. J. Roy. Astron. Soc.91, 569–596.
- Chao, B. F., andIz, H. B. (1992),Does Polar Motion Influence the Occurrence of Earthquakes, EOS, Trans. Am. Geophys. Union73, 79.
- Chao, B. F. (1993),Excitation of Earth's Polar Motion by Atmospheric Angular Momentum Variations, 1980–1990, Geophys. Res. Lett.20, 253–256.
- Chao, B. F., andGross, R. S. (1995),Changes of the Earth's Rotational Energy Induced by Earthquakes, Geophys. J. Int., in press.
- Chao, B. F., Gross, R. S., andDong, D. N. (1995),Global Gravitational Energy Changes Induced by Earthquakes, Geophys. J. Int., in press.
- Dahlen, F. A. (1971),The Excitation of the Chandler Wobble by Earthquakes, Geophys. J. R. Astr. Soc.25, 157–206.
- Dahlen, F. A. (1973),A Correction to the Excitation of the Chandler Wobble by Earthquakes, Geophys. J. R. Astr. Soc.32, 203–217.
- Dziewonski, A. M., Ekström, G., andSalganik, M. P. (1993),Centroid Moment Tensor Solutions for October–December, 1992, Phys. Earth Planet. Int.80, 89–103.
- Eubanks, T. M.,Variations in the orientation of the earth. InContributions of Space Geodesy to Geodynamics: Earth Dynamics (eds. Smith, D. E., and Turcott, D. L.) (AGU, Washington, D.C. 1993), pp. 1–54.
- Gilbert, F. (1970),Excitation of the Normal Modes of the Earth by Earthquake Sources. Geophys. J. R. Astr. Soc.22, 223–226.
- Gilbert, F., andDziewonski, A. M. (1975),An Application of Normal Mode Theory to the Retrieval of Structural Parameters and Source Mechanisms from Seismic Spectra, Phil. Trans. R. Soc. LondonA-278, 187–269.
- Gross, R. S. (1986),The Influence of Earthquakes on the Chandler Wobble during 1977–1983, Geophys. J. R. Astr. Soc.85, 161–177.
- Gross, R. S. (1994),A combination of Earth Orientation Data: Space 93, IERS Technical Note17: Earth Orientation, Reference Frames and Atmospheric Excitation Functions, Obs. de Paris.
- Kanamori, H. (1970),The Alaska Earthquake of 1964: Radiation of Long-period Surface Waves and Source Mechanism, J. Geophys. Res.75, 5029–5040.
- Kanamori, H., andCipar, J. J. (1974),Focal Process of the Great Chilean Earthquake May 22, 1960, Phys. Earth. Planet. Int.9, 128–136.
- Kanamori, H. (1976),Are Earthquakes a Major Cause of the Chandler Wobble? Nature262, 254–255.
- Kuehne, J., Johnson, S., andWilson, C. R. (1993),Atmospheric Excitation of Nonseasonal Polar Motion, J. Geophys. Res.98, 19973–19978.
- Lambeck, K. The Earth's Variable Rotation (Cambridge Univ. Press, New York 1980).
- Lambert, W. D. (1925),The Variation of Latitude, Tides, and Earthquakes, Proc. 3rd Pan-Pacific Science Congress, Tokyo, 1517–1522.
- Mansinha, L., andSmylie, D. E. (1967),Effects of Earthquakes on the Chandler Wobble and the Secular Pole Shift, J. Geophys. Res.72, 4731–4743.
- Munk, W. H., andMacDonald, G. J. F.,The Rotation of the Earth (Cambridge University Press, New York 1960).
- O'Connell, R. J., andDziewonski, A. M. (1976),Excitation of the Chandler Wobble by Large Earthquakes, Nature262, 259–262.
- Press, F. (1965),Displacements, Strains, and Tilts at Teleseismic Distances, J. Geophys. Res.70, 2395–2412.
- Rice, J. R., andChinnery, M. A. (1972), On the Calculation of Changes in the Earth's Inertia Tensor due to Faulting. Geophys. J. R. Astr. Soc.29, 79–90.
- Smylie, D. E., andManisinha, L. (1971),The Elasticity Theory of Dislocations in Real Earth Models and Changes in the Rotation of the Earth, Geophys. J. Res.23, 329–354.
- Souriau, A., andCazenave, A. (1985),Reevaluation of the Chandler Wobble Seismic Excitation from Recent Data, Earth Planet. Sci. Lett.75, 410–416.
- Thomson, D. J. (1982),Spectrum Estimation and Harmonic Analysis, Proc. IEEE70, 1055–1096.
- Seismic excitation of the polar motion, 1977–1993
pure and applied geophysics
Volume 146, Issue 3-4 , pp 407-419
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- polar motion
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- 1. Geodynamics Branch, NASA Goddard Space Flight Center, 20771, Greenbelt, Maryland, USA
- 2. Jet Propulsion Laboratory, California Institute of Technology, 91109, Pasadena, CA, USA
- 3. Beijing Astronomical Observatory, Chinese Academy of Sciences, 100080, Beijing, China