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First analyses of broadband records on the Geoscope Network: Potential for detailed studies of mantle discontinuities
Author(s) -
Souriau Annie
Publication year - 1986
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl013i010p01011
Subject(s) - classification of discontinuities , discontinuity (linguistics) , geology , seismology , mantle (geology) , coda , broadband , crust , ridge , geophysics , paleontology , telecommunications , mathematical analysis , mathematics , computer science
Examples of the first analyses of broadband GEOSCOPE data at station SSB (France) show that these data will make possible a detailed study of the deep mantle discontinuities. Analysis of the P‐coda of earthquakes using specific methods suggests the existence of P to S conversions at 670 km depth beneath SSB for earthquakes with northern to eastern azimuths; a comparison with results from the NARS and Grafenberg arrays indicate that the 670 km discontinuity beneath western Europe is highly heterogeneous or horizontally discontinuous. A frequency analysis reveals that the relevant discontinuity is not very sharp ( ∽ 20 to 70 km thick). Besides, a sharp ( < 5 km thick) discontinuity at 900 km depth is observed beneath the Mid‐Atlantic Ridge from P reflections, giving PP precursors, for the strong March 1985 Chilean earthquake, but no 670 km discontinuity seems to be present beneath the Ridge.