TELESEISMIC PN ARRIVALS: INFLUENCE OF MANTLE VELOCITY GRADIENT AND CRUSTAL SCATTERING
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dc.contributor.author | Nielsen L. | |
dc.contributor.author | Thybo H. | |
dc.contributor.author | Morozov I.B. | |
dc.contributor.author | Smithson S.B. | |
dc.contributor.author | Solodilov L. | |
dc.date.accessioned | 2022-02-02T08:59:02Z | |
dc.date.available | 2022-02-02T08:59:02Z | |
dc.date.issued | 2003 | |
dc.identifier | https://elibrary.ru/item.asp?id=13439806 | |
dc.identifier.citation | Geophysical Journal International, 2003, 152, 2, F1-F7 | |
dc.identifier.issn | 0956-540X | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/34868 | |
dc.description.abstract | Teleseismic P-n phases with a long, high-amplitude coda, are observed to offsets 3000 km along the Peaceful Nuclear Explosion seismic profiles Quartz and Ruby. For the high-frequency (5 Hz) part of the Quartz data, which is shown here, coda lengths of more than 10 s can be visually observed in the seismic sections. We interpret the teleseismic P-n arrivals as multiple sub-Moho refractions (whispering-gallery phases), which travel over large distances due to a positive upper-mantle velocity gradient. The coda of these arrivals is explained by lower crustal scattering of the whispering-gallery phases from the mantle. The modelling is based on calculation of reflectivity and 2-D visco-elastic finite-difference synthetic seismograms. Our models are in agreement with other deep seismic data from continental areas, which typically show a reflective lower crust and an almost transparent uppermost mantle. The lower crustal heterogeneity is described by von Karman distribution with a standard deviation of 0.5 km s(-1) for the P-wave velocity and correlation lengths of 2.4 km (horizontally) and 0.6 km (vertically). The positive vertical upper-mantle velocity gradient of similar to0.004 km s(-1) km(-1), which is characteristic for profile Quartz, forms a waveguide which gives rise to the teleseismic P-n. It is not necessary to include upper-mantle heterogeneity in order to explain the characteristics of this arrival. | |
dc.subject | crust | |
dc.subject | nuclear explosions | |
dc.subject | refraction seismology | |
dc.subject | scattering | |
dc.subject | eismic-wave propagation | |
dc.subject | upper-mantle | |
dc.title | TELESEISMIC PN ARRIVALS: INFLUENCE OF MANTLE VELOCITY GRADIENT AND CRUSTAL SCATTERING | |
dc.type | Статья |
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