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Shear velocity from differential travel times of short-period ScS-P in New Hebrides, Fiji-Tonga, and Banda Sea regions

1975; Seismological Society of America; Volume: 65; Issue: 6 Linguagem: Inglês

10.1785/bssa0650061787

1943-3573

Mansur A. Choudhury, G. Poupinet, Guy Perrier,

Geological and Geochemical Analysis

abstract Behavior of P, S and ScS residuals as well as those of differential travel times of ScS-P from the Jeffreys-Bullen tables are analyzed. The phases have been read from short-period records of the Antarctic station, Dumont d'Urville (DRV); the earthquakes originating in New Hebrides, Fiji-Tonga, and Banda Sea regions. P residuals from all regions show a mean value of about −1 sec. On the contrary, S and ScS residuals, well correlated among themselves, show important regional as well as focal-depth dependence. ScS-P residuals from shallow and intermediate shocks are largely positive for New Hebrides and largely negative for Banda Sea; those from intermediate shocks are moderately positive for Fiji-Tonga. The anomalies disappear at depths greater than about 200 km. Upper mantle shear velocity models are presented for the three regions. The models are discussed in relation to a sinking lithosphere.