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Propagation of high frequency Pn waves at great distances in the central and South Pacific and its implications for the structure of the lower lithosphere

Talandier Jacques, Bouchon Michel. 1979. Journal of Geophysical Research.
Propagation of high frequency Pn waves at great distances in the central and South Pacific and its implications for the structure of the lower lithosphere
ARTICLE, (1979 ) - PUBLISHEDVERSION - Français (fr-FR)
Journal of Geophysical Research
OPENACCESS - American Geophysical Union.
Audience : RESEARCHERS
Journal of Geophysical Research
Sujet
Geology, Earth Sciences, info:eu-repo/classification/ddc/551, info:eu-repo/classification/ddc/550
Domaines
Géologie
Description


Using 17 seismic stations in French Polynesia, we study the propagation of high-frequency Pn waves in the Central and South-Central Pacific. This study is prompted by the presence of striking Pn wave phases on the seismograms of the Hawaii earthquakes recorded in the Tuamotu and Society islands (Tahiti), almost 40° away. The Pn velocity inferred from these observations (7.95±0.03 km/s) is in good agreement with the values obtained in the North Pacific by Walker (1977a, b) and shows the existence over most of the Pacific basin of a remarkably efficient Pn wave guide of relatively low velocity. Compared to Pn, Sn waves are much less efficiently transmitted. The Pn velocities measured from intraplate earthquakes in the South-Central Pacific suggest the presence of a 2–3% anisotropy in the wave guide, the direction of maximum velocity being parallel to the trend of the island chains. All these observations are interpreted as evidence of the presence of minimum velocity channels within the subcrustal lithosphere and a discussion of the models which can account for these features is presented.



Mots-clés
Langue
Français (fr-FR)
Auteurs
Talandier Jacques, Bouchon Michel
Contributeurs
Laboratoire de Détection et de Géophysique - Commissariat à l'Energie Atomique (Papeete), Laboratoire de Géophysique Interne - Université de Scientifique et médicale de Grenoble (Grenoble)
Sources
Journal of Geophysical Research, 84( B10), pp. 5613– 5619
Couverture
Central Pacific, South Pacific
Nom du journal
Journal of Geophysical Research