GEMMA, is a multidisciplinary research project that will produce the next generation of geodynamic models for the Macaronesian region, establishing a fundamental framework to assess and evaluate natural resources and geological hazards in the NE Atlantic. Macaronesia – which includes the mid-plate archipelagos of Madeira, the Canaries and Cape Verde, but also the Azores which is located at an active triple junction – is simultaneously the source of multiple high-impact geohazards and the ultimate expression of the enigmatic mantle-surface interactionsacting in the North Atlantic, making it an excellent natural laboratory to investigate many of the processes that govern the Earth’s internaldynamics. Critically, current geodynamic models are only partially satisfactory to answer the wide diversity of geological and geophysicalfeatures observed in Macaronesia, posing real challenges to scientists that investigate the generation mechanisms of geohazards and of theseafloor mineral and energy resources of the region.

The refinement of existing geodynamic models for this area of the North Atlantic is thusstrategic for countries such as Portugal, Spain, and Cape Verde, which hold sovereignty over these volcanic archipelagos, but are also of globalinterest given that the processes behind ocean island volcanism constitute one of the last frontiers in the comprehension of our Planet’s internaldynamics.

In this project, we plan to use the latest and improved precision of geodetic observations to monitor slow but relentless geophysical processesdue to Earth dynamics. Geodetic methods can simultaneously quantify millimetre-scale horizontal and vertical changes of the Earth’s surface(GNSS) and the detection of small variations on the density of it’s interior (Gravity). When combined with other deep-earth geophysical andgeological tools, geodetic observations may provide particularly powerful constraints on some of the most enigmatic aspects of the geodynamicprocesses that act within the crust and upper mantle, and which result in measurable topographical changes. The overarching goal of GEMMA is thus to reconcile modern, robust geodetic observations with the latest seismic tomography & anisotropy, magnetic, geological, and structuralstudies, in order to test and refine existing models for the processes acting in the region, and which include mechanisms such as plate strain,thermal subsidence, flexural loading, rifting, magmatic underplating, volcanic uplift, and dynamic topography. In particular we plan to explorethe following aspects:

  1. compare measured vs modeled rates of vertical motions for each island, at both human and geological timescales, and in response tomechanisms such as thermal, flexural (as a result of volcanic loading), tectonic subsidence (for islands on active rifts), uplift in response tomagmatic underplating, rift shoulder elevation (near the Terceira Rift), volcanic inflation (if local), and dynamic topography (if regional andlinked to large-scale mantle upwelling);
  2. refine plate strain rate maps using the horizontal component to quantify the amount of internal deformation in the oceanic domain of theNubian plate, and in particular in the vicinities of the Azores Triple Junction;
  3. integrate island vertical and horizontal deformation with the latest structural seafloor mapping, to realistically constrain deformation patternsand kinematic forces;
  4. develop new, more robust dynamic numerical models that account for topographical deformation in response to rifting and/or mantleupwelling, particularly suitable for the Azores;

To address these challenges, we will capitalize and work in synergy with other ongoing projects – such as the ERC-funded UPFLOW and the FCT-funded SIGHT – in a novel onshore-offshore approach that will be the basis for a more holistic and integrative view of the mechanisms acting toshape the topography of Macaronesia. In particular, we propose to integrate observations and analytical modeling with the latest advances innumerical modeling of geodynamic processes in order to test particular conceptual models and hypotheses that may explain the observedsignals. This will allow us to simultaneously produce robust solutions to explain the observed deformation patterns – on both the horizontal andvertical components – and gain insights on the dynamic mantle/surface processes, as well as their frontier conditions, going beyond previousstudies.

It is anticipated that GEMMA will thus result in novel geodynamic solutions to explain the forces and processes acting in the Macaronesianregion, more robust than any before. The knowledge arising from this research will also have indirect implications to other disciplines – such asin geohazards and resources – also being upstream of several applications in fields as diverse as navigation, engineering, and relative sea-levelstudies..