Unveiling Deep Earth Mantle Structures Beneath the Azores-Madeira-Canaries with UPFLOW data

Constraining upward mantle flow is essential for understanding global mantle dynamics and linking Earth's interior with surface processes. The ERC-funded UPFLOW (Upward Mantle Flow from Novel Seismic Observations) project addresses the limited understanding of mantle upwellings connecting the deep mantle to the surface by utilising advanced seismic imaging methods and conducting extensive data collection.

Between June 2021 and September 2022, UPFLOW deployed 50 and successfully recovered 49 ocean bottom seismometers (OBSs) across a ~1,000×2,000 km² area in the Azores-Madeira-Canaries region, with an average station spacing of ~150-200 km. This multinational collaboration involved institutions from Portugal (IPMA, IDL, Univ. of Lisbon, ISEL), Ireland (DIAS), the UK (UCL), Spain (ROA), and Germany (Potsdam University, GFZ, GEOMAR, AWI). The deployment utilized three OBS frame designs equipped with three-component wideband seismic sensors and hydrophones. The dataset exhibits high-quality recordings, including teleseismic, local seismic events, and non-seismic signals (e.g., whales, ships, and the Tonga eruption), with significant noise reduction observed in vertical component long-period data (T > ~30 s).

Initial tomographic results feature a preliminary P-wave model derived from ~8,000 multi-frequency (T ~2.7-30 s) body-wave travel time cross-correlation measurements and over 120 teleseismic events. Integrating UPFLOW's OBS data with global seismic datasets from temporary and permanent stations expands the dataset to approximately 600,000 multifrequency measurements. This comprehensive approach enables the construction of a global P-wave model with enhanced resolution throughout the entire mantle beneath the Azores-Madeira-Canaries region. We compare our new model with existing global tomography models and discuss its geodynamical implications in terms of mantle upwelling processes and their surface expressions.