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Pregled bibliografske jedinice broj: 446072

Časopis

Autori: Tkalčić, Hrvoje; Kennett, B.L.N.; Cormier, V.F.
Naslov: On the inner-outer core density contrast from PKiKP/PcP amplitude ratios and uncertainties caused by seismic noise
Izvornik: Geophysical journal international (0956-540X) 179 (2009), 1; 425-443
Vrsta rada: članak
Ključne riječi: time-series analysis • composition of the core; body waves; wave propagation
Sažetak:
The inner core boundary (ICB) of the earth is characterized by a discontinuous change in elastic properties between the liquid outer and solid inner core. In the ray theory approximation, a measure of the density contrast at the ICB is given by the amplitude ratio of P waves reflected from the core–mantle boundary (CMB ; PcP waves) and the ICB (PKiKP waves), since that ratio conveniently appears in an explicit form in the transmission/reflection coefficient equations. The results for inner–outer core density contrast derived from direct amplitude picks of these waves in the time domain have varied significantly among different authors. The transmission/reflection coefficients on the liquid–solid and solid–liquid boundaries derived from ground displacements enable a direct comparison between the amplitude measurements on displacement seismograms in the time domain and theoretical values. A new approach is proposed and applied to integrate effects of microseismic and signal-generated noise with the amplitude measurements, thus providing a direct maximal uncertainty measure. To suppress the effects of varying radiation pattern and distinctively different ray paths at longer epicentral distances, this new method was applied to high-quality arrivals of PcP and PKiKP waves from a nuclear explosion observed at epicentral distances 10°–20° from recording stations. The resulting uncertainties are high precluding precise estimates of the ICB density contrast, but provide a robust estimate of an upper bound from body waves of about 1100 kg m−3. Median values of two amplitude ratios observed around 17° epicentral distance indicate a small density contrast of 200–300 kg m−3 and suggest the existence of zones of suppressed density contrast between the inner and the outer core, a density contrast stronger than 5000 kg m−3 at the CMB, or a combination of both.
Projekt / tema: 119-1193086-1315
Izvorni jezik: ENG
Rad je indeksiran u
bazama podataka:
Current Contents Connect (CCC)
Scopus
SCI-EXP, SSCI i/ili A&HCI
Science Citation Index Expanded (SCI-EXP) (sastavni dio Web of Science Core Collectiona)
Kategorija: Znanstveni
Znanstvena područja:
Geologija
URL Internet adrese: http://www3.interscience.wiley.com/user/accessdenied?ID=122526679&Act=2138&Code=4719&Page=/cgi-bin/fulltext/122526679/PDFSTART
http://www3.interscience.wiley.com/journal/122526679/abstract
Broj citata:
Altmetric:
DOI: 10.1111/j.1365-246X.2009.04294.x
URL cjelovitog teksta:
Google Scholar: On the inner-outer core density contrast from PKiKP/PcP amplitude ratios and uncertainties caused by seismic noise
Upisao u CROSBI: mherak@geolpmf.hr (mherak@geolpmf.hr), 1. Ožu. 2010. u 16:44 sati



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