3-D Mapping of Attenuation in the Upper Mantle

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9405927 Romanowicz This research is a continuation of investigations of the 3-D anelastic structure of the mantle using seismological data. The recent work with mantle Rayleigh waves has resulted in a 3-D model of Q in the upper mantle, which has demonstrated that there is hope to extract useful information on the mantle's thermal structure, not redundant with elastic tomography results. Features of interest of this model include correlation with cooling plate models in the first 200 km of depth as well as two maxima in attenuation in the transition zone, correlated with hotspot strength distribution. This research will 1) investigate ways in which anelastic tomography results can be incorporated as additional constraints in dynamical modeling of the earth's mantle; 2) improve the resolution of the upper-mantle model by a) including new data available with the rapid expansion of the IRIS/GSN network, b) adding constraints form Love waves, c) taking into account effects of focusing explicitly; and 3) investigate lateral variations of Q in the lower mantle, using both body wave and normal mode data. ***