1IPGP - Institut de Physique du Globe de Paris (IPGP, 1 rue Jussieu, 75238 Paris cedex 05 ; Université Paris Diderot, Bât. Lamarck A case postale 7011, 75205 Paris CEDEX 13 - France)
Abstract : Some recent seismic studies have suggested the presence of a thin ultra-low P-wave velocity layer (ULVZ) at the base of the mantle, which is interpreted to be due to presence of partial melting. Partial melting would lead to a strong decrease of the S-wave velocity for which there is no seismic evidence. Such a decrease in the S-wave velocity would produce a strong precursor to SKS phase from the conversion of S to P at the upper boundary of the layer. We analyze records of events from the subduction zones in the south-west Pacific region obtained at stations in North America. At the source side, the converted phases propagate in the region, where the ultra-low P-wave velocity has been found earlier. Our analysis demonstrates that either the S-wave velocity drop in this layer is much smaller than predicted by the hypothesis of melting, or the layer is so thin (less than about 10-15 km) that it can not be detected with our technique.
https://hal-insu.archives-ouvertes.fr/insu-03596941 Contributor : Nathalie POTHIERConnect in order to contact the contributor Submitted on : Friday, March 4, 2022 - 2:00:50 PM Last modification on : Sunday, March 6, 2022 - 3:23:53 AM Long-term archiving on: : Sunday, June 5, 2022 - 7:12:32 PM
Eléonore Stutzmann, Lev Vinnik, Ana Ferreira, Satish Singh. Constraint on the S-wave velocity at the base of the mantle. Geophysical Research Letters, American Geophysical Union, 2000, 27, pp.1571-1574. ⟨10.1029/1999GL010984⟩. ⟨insu-03596941⟩