Sharpness of the mantle discontinuities

Autor:	K. Stammler, Grigoriy Kosarev, Rainer Kind, Sergey Oreshin, L. Vinnik, N. Petersen
Rok vydání:	1993
Předmět:	Seismometer P wave 550 - Earth sciences Classification of discontinuities Geodesy Mantle (geology) Linear gradient Geophysics Discontinuity (geotechnical engineering) Transition zone General Earth and Planetary Sciences Waveform Geology Seismology
Zdroj:	Geophysical Research Letters
ISSN:	0094-8276
DOI:	10.1029/93gl00684
Popis:	Seismic estimates of sharpness of the mantle discontinuities are important for constraining models of composition and temperature in the deep Earth but these data are difficult to obtain. We explore a possibility to determine sharpness of the major mantle discontinuities (those at depths around 400 and 650 km) from the broad-band records of phases converted from P to S underneath the receiver. Our estimates are obtained from a comparative analysis of waveforms of the converted phases and those of the P waves in the teleseismic records of BRV (Kazakhstan), GRF (Germany), NRE0 (Norway) and YKW (Canada). The data indicate that the shape of the pulse converted at the 400-km discontinuity is close to that of the P wave whereas the pulse of the 650-km conversion is substantially broader. We infer from this comparison that the 400-km discontinuity is sharp (width of the transition zone is less than 5–7 km). The 650-km transition is modelled by a linear gradient zone 20–30 km thick.
Databáze:	OpenAIRE
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