Earth free oscillation measurements with LCR-ET 26 Spring gravimeter

• Autorzy: Rajner M. , Rogowski J.B.
• Konferencja: Geodetic and Geodynamic Programmes of the Central Europe / Procedings of the EGU G 6.1 Symposium (3-08. 04. 2011; Vienna, Austria)
• Języki publikacji: EN

Abstrakty

EN

After strong earthquakes the Earth oscillates with spheroidal and toroidal modes. The former cause gravity changes which can be detected with sensitive instruments. For this purpose we used continuous gravity measurements with LaCoste&Romberg Earth Tide spring gravimeter from Józefosław Observatory. Spectral analyses of records show significant peaks in normal mode frequencies. This peaks are above noise level and their eigenfrequencies are in good agreement with seismic theories. We show here some examples of free oscillations registration after particular earthquakes and stacking method as well. Some remarks concerning noise level in gravity measurements and data treatment are also given.

Słowa kluczowe

EN

gravimetric measurements

PL

pomiary grawimetryczne

• Wydawca: Wydział Geodezji i Kartografii Politechniki Warszawskiej
• Czasopismo: Reports on Geodesy
• Rocznik: 2011
• Tom: z. 2/91
• Strony: 89--95
• Opis fizyczny: Bibliogr. 17 poz., rys., wykr.

Twórcy

autor

Rajner M.

autor

Rogowski J.B.

• Warsaw University of Technology, Departament of Geodesy and Geodetic Astronomy,

Bibliografia

• [1] Banka, D. and D. Crossley, 1999. Noise levels of superconducting gravimeters at seismic frequencies, Geophysical Journal Int., 139, 87–97.
• [2] Barlik, M., M. Rajner and T. Olszak, 2010. Analysis of Measurements Collected in Gravity Laboratory in Józefosław Observatory during 2007-2010, Proceednigs: IAG Symposium on Terrestial Gravimetry, Sankt Petersburg, 22-25 June, 2010, in press.
• [3] Bogusz, J., 2002. New tidal gravimetric laboratory in Jozefoslaw, Reports on Geodesy, 61(1), 153–300.
• [4] Dziewoński, A. and D. Anderson, 1981. Preliminary reference Earth model, Physics of the Earth and Planetary Interior, 25, 297–356.
• [5] Gilbert, F. and A. Dziewoński, 1975. An application of normal mode theory to the retrival of structural parameters ans source mechanism from seismic spectra, Phil. Trans. R. Soc. Lond., 278, 187–269.
• [6] Masters, T.G. and R. Widmer, 1995. Free Oscollations: Frequencies and Attenuations, Ahrens, T.J., ed., Global Earth Physics, A Handbook of Physical Constants, Washington, 104–125.
• [7] Park, J., T.-R. Song, J. Tromp, E. Okal, S. Stein, G. Roult, E. Clévéde, G. Laske, H. Kanamori, P. Davis, J. Berger, C. Braitenberg, M. Van Camp, X. Lei, H. Sun, H. Xu and S. Rosat, 2005. Earth’s Free Oscillations Excited by the 26 December 2004 Sumatra-Andaman Earthquake, Science, 1139–1144.
• [8] Peterson, 1993. Observations and modeling of seismic background noise, USGS open file Report, 85–288.
• [9] Rajner, M., 2010. Investigation in Tidal Gravity Results in Józefosław Observatory, Reports on Geodesy, 88(1), 7–14.
• [10] Resovsky, J. and M. Ritzwoller, 1998. New and refined constraints in the three-dimensional Earth structure from normal modes below 3mHz, J. of Geoph. Res., 103, 783–810.
• [11] Richter, B., H.-G. Wenzel, Zürn and F. Klopping, 1995. From Chandler wobble to free oscillations: comparison of cryogenic gravimeters and other instruments in a wide period range, Physics of the Earth and Planetary Interior, 131–148.
• [12] Rosat, S., J. Hinderer, J.-P. Boy and D. Crossley, 2004. Performance of superconducting graimeters from long-period seismology to tides, Journal of Geodynamics, 461–476.
• [13] Rosat, S., S. Watada and T. Sato, 2007. Geographical variations of the 0S0 normal mode amplitude: predictions and observations after the Sumatra-Andaman earthquake, Earth Planets Space, 59, 307–311.
• [14] Suda, N., K. Nawa and Y. Fukao, 1998. Earth’s Background Free Oscillation, Science, 279, 2089–2091.
• [15] Widmer-Schnidrig, R., 2003. What can Superconducting gravimeters contribute to normalmode seismology? , Bull. Seism. Soc. Am., 93(3), 1370–1380.
• [16] Zürn, W., G. Laske, R. Widmer-Schnidrig and F. Gilbert, 2000. Observation of Coriolis coupled modes below 1 mHZ, Geophysical Journal Int., 143, 113–118.
• [17] Zürn, W. and R. Widmer, 1995. On noise reduction in vertical seismic records below 2 mHz using local barometric pressure, Geophysical Research Letters, 22, 3537–3540.