The Rheology of the Lithosphere Beneath the Hawaiian Ridge

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A joint effort by the NSF, University of Hawaii, and the privately funded Schmidt Ocean Institute in 2014 surveyed the seafloor along the western Hawaiian Ridge and obtained nearly complete coverage in water depths greater than 50 m of the 2500-km-long chain of extinct volcanoes. This exceptional data set will be used to study the strength of the tectonic plate. The gravity data and seafloor maps record the downward bending of the tectonic plate when volcanos are built on it. Models will be used to simulate this bending and provide an estimate of the strength of the tectonic plate. The results will complement, or could even revise, results produced by experimental methods in which the strength of rock samples is measured in the laboratory. The project will contribute to the understanding of earthquakes which requires an understanding of rock strength. The project will also contribute to the professional training of graduate and undergraduate students in advanced STEM fields. In addition, a graduate student seminar will be developed whose topic will be on the strength of the plate, and guest lectures will be given remotely via Skype and made available on iTunes University and YouTube sites.Rheologic properties of the Pacific Ocean lithosphere will be investigated along the older section of the Hawaiian Ridge. In this area, volcanoes of different sizes have erupted on crust of roughly the same age (about 85 Ma). This will allow the researchers to isolate the effect of the size of the load and age of the load from the effect of the thermal age of the lithosphere in their models of the lithosphere response to the loads. The researchers will use multibeam bathymetry and gravity data collected in this region to quantify the rheological laws that control the flexure of the underlying lithosphere and thus, characterize the strength of the lithosphere. This study could motivate revisions to our understanding of lithosphere rheology overall.