Seismic Attenuation and S‐Velocity Structures in D ′ ′ Beneath Central America Using 1‐D Full‐Waveform Inversion

We use one‐dimensional full‐waveform inversion to simultaneously infer the S‐velocity ( V S ) and anelastic ( Q S ) structures of the lowermost 480 km of the mantle in 11 contiguous corridors located beneath Northern South America and Central America. Previous studies in this region have reported the presence of slabs at the core‐mantle boundary (CMB) and large variations in the depth of the D ′ ′discontinuity, suggesting local temperature variations. We use transverse component waveform data cut around the ScS phase, including the Scd phase due to the D ′ ′discontinuity, from 31 events beneath South America recorded at USArray stations. The minimum period used in this study is 8 s, allowing us to constrain the fine‐scale structure of the D ′ ′region and the depth of the D ′ ′discontinuity. We correct the data for the effect of amplitude focusing due to lateral velocity anomalies (i.e., out‐of‐plane focusing effect) in D ′ ′on the inferred Q S structure using three‐dimensional waveform calculations. We show that, in the explored region, corrections for out‐of‐plane focusing effects are necessary to obtain Q S models that have a reasonable interpretation in terms of temperature and fraction of post‐perovskite (pPv). Our final models show regions with high V S , high Q S , and an elevated D ′ ′discontinuity, surrounding a low‐velocity corridor with lower Q S and a depressed D ′ ′discontinuity that can be explained by local temperature variations. However, differences between temperature perturbations inferred from V S and Q S suggest lateral variations in the fraction of pPv.