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Elucidating the Hawaiian plume dynamics by a joint MT and seismic experiment

 PI:  E. Attias (UTIG)  
co-PIs:  N. Harmon (WHOI), C. Rychert  (WHOI), A. Haroon (HIGP)
Collaborators: S. Wang (NTNU), H. Turner (Chaminade University)


The Hawaiian hotspot consists of two crucial geological/tectonic components: A plume of molten rock which connects the Hawaiian Islands to the deep mantle, whose location, diameter, and depth extent are still subject to heated debate, and an associated bathymetric rise (swell) whose dynamics and geology also are still subject to debate. While progress has been made using seismic methods to address the geometry of the Hawaiian plume, detecting and quantifying variations in temperature, composition, and melt fraction are still challenging. 



The non-invasive MagnetoTelluric (MT) method uses natural time variations in Earth’s magnetic field, primarily caused by solar winds, to measure the crust’s and mantle's electrical conductivity. Conductivity is highly sensitive to changes in temperature and melts content. In this project, we will conduct a regional-scale island and ocean-bottom deployment of 70 marine MT instruments and 11 land MT stations to study the plume and swell associated with the Hawaiian hotspot. Our MT survey will complement the previously collected seismological data (Hawaiian PLUME Project). Thus, enabling us to test hypotheses relating to the nature and dynamics of the Hawaiian plume that cannot be unequivocally tested with either MT or seismic data alone.



The EM-PLUME experiment: Map of past and proposed MT receivers and ocean bottom differential pressure gauge (DPG) as seismometers.

’Hawaiian’ plume 3D synthetic MT modeling  
Upper panel: The model finite-element discretization.
Bottom panel: Inversion model for determinant data. The determinant inversion mitigates 3D effects, prominent features in TE and TM-mode inversions (Wang et al., 2020). The triangles mark the MT sites, and dashed lines denote the boundaries of the plume.

EM-PLUME will provide powerful constraints on the subsurface geology, including the position and lateral extent of the region of magma upwelling beneath Hawaii, its depth of origin, the amount of melt within this volcanic system, the 3D thermal structure beneath the swell, and the spatial and implied temporal extent of any magma ponded at the lithosphere. The MT and seismic datasets will be analyzed in a novel joint inversion framework. This integrated approach will contribute to our understanding of one of the essential magmatic systems on Earth in terms of planetary convection, plate tectonics, and island-building mechanism.