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FRINATEK-Fri prosj.st. mat.,naturv.,tek

Middle Atlantic Ridge Study with Three-Dimensional Magnetotelluric novel Techniques

Alternative title: Studier av den Midt-Atlantiske ryggen ved hjelp tredimensjonale magnetotelluriske teknikker

Awarded: NOK 7.8 mill.

Investigating Earth’s interior is crucial for the understanding of the planet and how it operates. However, Earth’s deep structures are still elusive. Magnetotellurics (MT), as a green geophysical method, records Earth’s natural electromagnetic fields to study the electrical resistivity of the Earth’s interior down to a few hundred kilometers. Ocean ridges have a simpler geological history than continents and so are ideal laboratories to study Earth’s interior. Therefore, it is valuable to build a reliable three-dimensional (3D) resistivity model from MT data collected at ocean ridges. Furthermore, such a model would improve the understanding of to what extent rocks are molten at depths and how much water exists at those depths beneath the ocean ridges. Most importantly, such a model will be quantified with uncertainties. However, the tools for generating such a reliable 3D resistivity model with marine MT data are missing. The primary objectives of MARS3DMT are: (1) Develop a 3D marine MT inversion incorporating bathymetry and coastlines using finite element and Gauss-Newton methods; (2) Develop a 3D MT inversion with quantified uncertainties using fast Fourier Transform and Bayesian methods; (3) Construct the first detailed 3D resistivity model with quantified uncertainties beneath the Middle Atlantic Ridge (MAR). The secondary objectives are: (1) Interpret the geological structures beneath MAR with uncertainty quantification through Bayesian inference; (2) Quantify the melt fraction and the water content beneath the MAR with uncertainties. There are four work packages in MARS3DMT. The first two focus on algorithm development, the third interpretation, and the fourth management. The inversion algorithms to be developed are not only applicable to the studies of Earth’s interior, but also applicable to seabed metal exploration, offshore geothermal exploration, seafloor landslide studies, undersea CO2 monitoring, and subsurface ocean discovery on other planets.

Revealing Earth’s interior beneath the oceans is crucial for the understanding of the planet and how it operates. However, Earth’s deep structures are still elusive. Magnetotellurics (MT), as a green geophysical method, utilizes Earth’s natural electromagnetic fields to study the electrical resistivity of the Earth’s interior down to a few hundred kilometers. Ocean ridges have a simpler geological history than continents and so are ideal laboratories to study Earth’s interior. Therefore, it is valuable to build a reliable three-dimensional (3D) resistivity model from MT data collected at ocean ridges. Furthermore, such a model would dramatically improve the understanding of partial melts, melt fraction, and water content beneath the ocean ridges, especially with quantified model uncertainties. However, the tools for generating reliable 3D resistivity models with marine MT data are missing. The primary objectives of MARS3DMT are: (1) Develop a 3D marine MT inversion incorporating bathymetry and coastlines using finite element and Gauss-Newton methods; (2) Develop a 3D MT inversion with quantified uncertainties using fast Fourier Transform (FFT) and Bayesian methods; (3) Construct the first detailed 3D resistivity model with quantified uncertainties beneath the Middle Atlantic Ridge (MAR). The secondary objectives are: (1) Interpret the geological structures beneath MAR with rigorous uncertainty quantification through Bayesian inference; (2) Quantify the melt fraction and the water content beneath the MAR with uncertainties. There are four work packages in MARS3DMT. The first two focus on algorithm developments, the third interpretation, and the fourth management. The inversion algorithms developed in this project are not only applicable to the studies of Earth’s interior, but also open a new path for seabed metal exploration, offshore geothermal exploration, seafloor landslide studies, undersea CO2 monitoring, and subsurface ocean discovery on other planets.

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FRINATEK-Fri prosj.st. mat.,naturv.,tek