Magnetotelluric investigation of fluid- and melt-involved processes in the Central American subduction zone

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The proposal presented here aims at extending the work which has recently been carried out at the Central American margin during the initial phase of project “MT Central America”. Two regional-scale, long-period magnetotelluric profiles at the margin were conducted in north-western Costa Rica and northwestern Nicaragua, which yielded distinct electromagnetic images of fluids and melts of the subduction zone, in accordance with along-strike variation of other geophysical and geochemical parameters.The need to extend the current project is based on: i) The geoelectric parameters along both transects clearly express three-dimensional characteristics which have to be modeled. ii) The integration of offshore measurements conducted by IFM-Geomar into the onshore data set has to be completed. iii) Furthermore, Scripps Oceanographic Institution will carry out an offshore transect across the Nicaraguan trench, which shall be supplemented and completed with new stations on land. The final goal is to achieve a full three-dimensional image of the margin, to correlate the electric parameters with seismological and geochemical findings and enhance understanding of the along-strike trends, particularly the sudden deflection of the volcanic arc at the Nicaraguan - Costa Rican border.