Extended Data Figure 7 : Linear resolution analysis for synthetic ‘hanging’ plume input structures in the upper mantle and transition zone.

From: Broad plumes rooted at the base of the Earth's mantle beneath major hotspots

Extended Data Figure 7

Like those in Extended Data Figs 4 and 5, these plumes have an overall width of 600 km and a cosine-cap lateral cross-section, as well as −2% maximum amplitude, but are now cut at 410-km (left panels) or 1,000-km (right panels) depth. This experiment is designed to assess the effect of depth-smearing in SEMUCB-WM1. Upper panels, hanging-plume input models. Lower panels, output models when inputs are placed beneath Hawaii. We note that in general the structures retrieved are quite symmetrical and exhibit the appropriate depth extent, with the exception of the plume truncated at 1,000 km, which shows a weak eastward-trending band extending to the CMB. We note that this artefact is very weak, generally less than 0.1% amplitude, as illustrated in the bottom panel, where structure below 0.1% is masked (that is, the band is at least 20× weaker than the −2% input structure). Furthermore, we note that this feature is not at all like the plume we image beneath Hawaii, as it possesses a very different trend and amplitude profile.