Plumbing System of Hunga Tonga Hunga Ha’apai Volcano

The Hunga Tonga Hunga Ha’apai submarine volcano has experienced repeated eruptions in the latest decades. The recent one, in January 2022, released an enormous amount of energy inducing global perturbations, as tsunamis and atmospheric waves. The structure of the volcano is poorly understood, especially its internal structure. Deep-seated magmatic connections are difficult to define or visualize. We use a high-resolution gravity data set obtained via satellite to calculate the Bouguer anomaly over its structure, to perform a preliminary exploration of its interior. Executing 3D gravity inversions, we find a complex plumbing system with various exhaust trajectories and multiple surface pockets of low-density material within the volcanic edifice; some appear to be associated with ring fractures. This is in line with the report of the 2009 eruption, described as beginning from multiple vents. We found no signs of a magma chamber within 6 km depth, although several volcanic conduits are identified from such depth to the surface. Density variations occur within a plumbing conduit or may vary from one conduit to another in the same volcano. These models yield quantitative estimates for areas of magma-water interaction, constituting a baseline to compare with structural changes to be induced in future eruptions.