Volcano models show that the architecture of the magma conduit systems between the Earth’s mantle and the surface and the way magma evolves through these systems play a fundamental role in the construction and development of volcanic edifices. However, due to the inaccessibility of most active volcanic systems to high-resolution imaging, the detailed morphology of the most superficial magma reservoirs and the relationship between the onset of magma upwelling and eruption dynamics are largely unknown. By imaging the magmatic system beneath the East Pacific Ridge at high resolution and in 3D for the first time, an international team led by Milena Marjanovic, CNRS researcher at the Institute of Globe Physics in Paris, is shedding light on the morphology of the magmatic lenses. last magma stages before lava eruptions on the surface.
The study, published September 29 in the journal Science Advances, shows that the shape of these small magma reservoirs is reminiscent of the processes of reloading and expelling magma, influencing the dynamics of future eruptions.
In a study published September 29 in the journal Science Advances, an international team including scientists from CNRS, the Paris Institute of Globe Physics and Paris Cité University presents new, high-resolution seismic images that shed light on the small-scale architecture of the network of the shallowest magma bodies located beneath an eruption zone of the East Pacific Ridge. These images are the result of a collaboration with the geophysics industry that enabled the use of a state-of-the-art imaging technique, and were obtained by inverting the waveforms of seismic reflection data acquired during oceanographic campaigns in 2008.
The study shows that these lenses, previously modeled as smooth bodies, actually have ridges and valleys that are interpreted as zones where the dikes (magma seams rising from the reservoir to the surface) are located. This particular morphology would be formed by the processes of magma recharge from the mantle and magma extraction to the surface. The repetition of these processes leaves an impression related to the concentration of stresses induced by the topography, contributing to the nucleation of the dikes and the initiation of the ascent of magma to the surface and, more generally, to the dynamics of subsequent eruptions.
Seafloor topography and tectonics (left) and 3D morphology of subsurface magmatic lenses (right) of a section of the East Pacific Ridge (9°50′ N).
© Marjanovic – CNRS – IPGP
By incorporating these new results into the latest generation of three-dimensional numerical models, it should now be possible to obtain a more realistic representation of volcanic systems, which will contribute to better localization of eruptions and thus improve risk assessment.
reference
Insights into dike nucleation and eruption dynamics from high-resolution seismic images of the East Pacific Rise magmatic system,
Marjanović et al., Sci. Adv. 9, 2023. DOI: 10.1126/sciadv.adi2698