INTERPRETING D SEISMIC STRUCTURE USING SYNTHETIC WAVEFORMS COMPUTED FROM DYNAMIC MODELS
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dc.contributor.author | Sidorin I. | |
dc.contributor.author | Gurnis M. | |
dc.contributor.author | Helmberger D.V. | |
dc.contributor.author | Ding X. | |
dc.date.accessioned | 2020-12-29T10:10:04Z | |
dc.date.available | 2020-12-29T10:10:04Z | |
dc.date.issued | 1998 | |
dc.identifier | https://elibrary.ru/item.asp?id=88399 | |
dc.identifier.citation | Earth and Planetary Science Letters, 1998, , 1, 31-41 | |
dc.identifier.issn | 0012-821X | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/21659 | |
dc.description.abstract | We have formulated dynamic models of processes hypothesized to give rise to observed seismological structure at the base of the mantle. One dimensional seismic models are determined from thermo-chemical convection calculations from which synthetic waveforms are computed. Of the three scenarios studied, (1) a thermal slab, (2) a thermal slab interacting with simple chemical layer, and (3) a thermal slab interacting with a phase transition, the strength of seismic phases computed from (3) best correlates with the global geography of the observed D triplication. Seismic structures predicted by (1) or (2) are inconsistent with the global geography and strength of the triplication. Our successful model motivates a new class of 1-D seismic models with two mild gradients and a small discontinuity. To test this hypothesis, we searched for seismic models that both contain these features and fit D seismic observations. Our preferred model contains a gentle positive gradient initiated 350 km above the CMB and a 1% jump in S-velocity near 200 km. A strong negative gradient begins about 100 km above the CMB, similar to previous studies representing the lower thermal boundary layer. With the reduced first-order discontinuity, the P-wave triplication becomes too small to observe and provides a simple explanation for the observed weakness of the P in proportion to the S triplication. | |
dc.subject | MANTLE | |
dc.subject | CONVECTION | |
dc.subject | SEISMOLOGY | |
dc.subject | MODELS | |
dc.title | INTERPRETING D SEISMIC STRUCTURE USING SYNTHETIC WAVEFORMS COMPUTED FROM DYNAMIC MODELS | |
dc.type | Статья |
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