The Hawaiian islands are part of a volcanic island chain that formed as the Pacific plate moved over a deep mantle hotspot. This project will apply new techniques to an existing dataset of geophysical profiles that span the Hawaiian-Emperor Seamount Chain. A key focus of the study will be to constrain the amount of melt that solidifies in the crust and upper mantle instead of erupting at the surface. The results will be important for understanding the formation and expansion of the Hawaiian Islands. The project will include training of graduate students and mentorship of undergraduate students. This study will gain new insight into the internal structure and formation processes of the Hawaiian–Emperor Seamount Chain and place key constraints on the properties of the oceanic lithosphere. The project will apply seismic tomography, full-waveform modeling, and complementary geophysical techniques to data from ocean bottom seismographs deployed along four seismic profiles. Research objectives are to 1) Characterize magmatic underplating, its contribution to the magma budget, and its control on flexural response, and 2) Identify zones of tensile cracking and fluid alteration in the volcanic moat and arch and determine how these zones affect lithospheric bending. The results will have implications for plate deformation and lithospheric rheology. Within the interior of tectonic plates, these are important factors for understanding what controls new volcanism. Graduate students wil