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Inversion du tenseur des moments pour des séismes de magnitude modérée enregistrés à des distances régionales

Abstract : The aim of this work was to determine the nature of a seismic source from regional waveforms, and to study its temporal complexity in terms of sub-events. For this purpose, a linear inversion method was used to estimate the seismic moment tensor of the source. A previous bibliographic study allowed us to choose for suitable inversion and wave propagation modeling methods. In a first step, we have tested our inversion program on synthetic data, thus removing problems of propagation modeling. We studied the influence of various seismic phases and source depth on the quality of the inversion results. Impact from station network geometry and source mechanism was also investigated. In a second step, we have studied three real events. We were first interested in a mine collapse with a magnitude of 4.8. This event, for which source characteristics were a priori known, was used to define an inversion methodology. We also succeeded in extracting an isotropie component in the source of about 35%. Then, we have studied the event of Roermond (April 1992), as a good reference tectonic event. The mechanism obtained from the inversion of low frequency data is coherent with previous puhlished studies. The validity of the method was estimated from inversions in a higher frequency range. Finally, we have processed a smaller tectonic event, for which a near field signal was available. We have shown that mechanisms derived from independent inversions, using near field and far field recordings, yield compatible results. Furthermore, their deviatoric solution is consistent with the one obtained from first motion analysis.
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https://tel.archives-ouvertes.fr/tel-00749713
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Submitted on : Thursday, November 8, 2012 - 11:15:55 AM
Last modification on : Thursday, November 19, 2020 - 3:54:28 PM
Long-term archiving on: : Saturday, December 17, 2016 - 8:59:42 AM

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  • HAL Id : tel-00749713, version 1

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Valérie Teyssonyere. Inversion du tenseur des moments pour des séismes de magnitude modérée enregistrés à des distances régionales. Géophysique [physics.geo-ph]. Université Joseph-Fourier - Grenoble I, 2001. Français. ⟨tel-00749713⟩

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