%0 Journal Article %T Elastic and anelastic structure of the lowermost mantle beneath the Western Pacific from waveform inversion %+ Institut de Physique du Globe de Paris (IPGP) %A Konishi, Kensuke %A Fuji, Nobuaki %A Deschamps, Frédéric %< avec comité de lecture %@ 0956-540X %J Geophysical Journal International %I Oxford University Press (OUP) %V 208 %P 1290-1304 %8 2017 %D 2017 %Z 2017GeoJI.208.1290K %R 10.1093/gji/ggw450 %K Inverse theory %K Elasticity and anelasticity %K Body waves %K Seismic attenuation %K Seismic tomography %K Pacific Ocean %Z Sciences of the Universe [physics] %Z Sciences of the Universe [physics]/Earth SciencesJournal articles %X We investigate the elastic and anelastic structure of the lowermost mantle at the western edge of the Pacific large low shear velocity province (LLSVP) by inverting a collection of S and ScS waveforms. The transverse component data were obtained from F-net for 31 deep earthquakes beneath Tonga and Fiji, filtered between 12.5 and 200 s. We observe a regional variation of S and ScS arrival times and amplitude ratios, according to which we divide our region of interest into three subregions. For each of these subregions, we then perform 1-D (depth-dependent) waveform inversions simultaneously for radial profiles of shear wave velocity (VS) and seismic quality factor (Q). Models for all three subregions show low VS and low Q structures from 2000 km depth down to the core-mantle boundary. We further find that VS and Q in the central subregion, sampling the Caroline plume, are substantially lower than in the surrounding regions, whatever the depth. In the central subregion, VS-anomalies with respect to PREM (dVS) and Q are about -2.5 per cent and 216 at a depth of 2850 km, and -0.6 per cent and 263 at a depth of 2000 km. By contrast, in the two other regions, dVS and Q are -2.2 per cent and 261 at a depth of 2850 km, and -0.3 per cent and 291 at a depth of 2000 km. At depths greater than ∼2500 km, these differences may indicate lateral variations in temperature of ∼100 K within the Pacific LLSVP. At shallower depths, they may be due to the temperature difference between the Caroline plume and its surroundings, and possibly to a small fraction of iron-rich material entrained by the plume. %G English %2 https://insu.hal.science/insu-03748871/document %2 https://insu.hal.science/insu-03748871/file/ggw450.pdf %L insu-03748871 %U https://insu.hal.science/insu-03748871 %~ INSU %~ UNIV-PARIS7 %~ AFRIQ %~ CNRS %~ IPGP %~ USPC %~ SORBONNE-UNIVERSITE %~ UNIV-PARIS %~ SU-TI %~ ALLIANCE-SU