Award: OCE-0929881

This project was part of a collaborative, multidisciplinary effort to observe sites of two recent submarine volcanic eruptions in the NE Lau Basin (in the waters of the Kingdom of Tonga). The eruptions were discovered by chemical and physical characteristics of the seawater above the volcanoes in Nov 2008, after which a team of us proposed to get US shipboard assets back to the area asap to make observations of the volcanology, hydrology, gas output and deep seafloor ecology, all of which are known to change rapidly during and after eruptions. This grant covered two components of the research: Geological/volcanological/geochemical studies of eruptiing and/or recently erupted lavas, including producing short-fusw, high resolution (+- a week or two) eruption ages using radioactive 210Po in the lavas (half life of 138.4 days) and geochemical studies of organic chemicals and biomarkers in vent fluids. Both aspects of the projects were unqualified successes and have contributed to our understanding of the deep sea eruptions. During the May 2009 cruise funded by this and related collaborative proposals, we discovered and studied an active eruption at W. Mata volcano, and a recently active eruption on the North East lau Spreading Center (NELSC), which we named Puipui ("curtain" in Tongan), because of the incredible folds and flow patterns in the lava flow. See our shipboard blog at laueruptions.blogspot.com for intitial discoveries and descriptions.. Submarine eruptions in the deep sea (below about 3000 ft water depth) are the dominant form of volcanism on Earth, but because they are so remote and difficult to detect, we have very few observations of them in the aftermath and before this program had never witnessed one. The closest we've come to seeing one is observations of a moderate depth, comparatively small eruption at NW Rota Seamount in the Mariana Islands back in 2004. This time around, we witnessed an active eruption at WW. Mata volcano, which has a summit at 1200 m water depth (about 3700 feet). The spectacular eruptuion included both lava flows and huge gas fueled explosions of molten magma fragments. The chemistry of the lavas was boninite, a very rare magma type only found in young subduction zone environments, and not known to have erupted on Earth in the past 2 million years. This discovery added to the exitement and scientific relevance of the findings of the research expedition, bercause for the first time ever we were able to study the chemistry and natural radioactivity of a fresh sample of this rare rock type, allowing us to decipher how it formed and the timescales of the magmatic processes involved. Many of the results of this expedition and follow up lab work are still in the processes of being published. Two papers are accepted for publication and co-authored by this project's lead investigator (one about the West Mata eruption and one about volcanic plumes above the NELSC eruption site). Additionally, more that 20 presentations have been made at scientific conferences by the various investigators on this overall project, and images and video have been posted to the website of our collaborators in the Vents program of NOAA-PMEL. Finally, descriptions and vidoe of these submarine eruptions and their discovery were a major component of a series of NSF sponsored, Ridge 2000 program Distinguished Lecturer presentations Ken Rubin made for scientists and the general public at universities accross the US in 2011. All of the latter contribute to the broader impacts of the research. This intellectual merit of the study can be summarized as having greatly increased our understanding of: the causes and consequences of explosive volcanism in the sea the time scales of magma formation and eruption processes in the deep sea the time scales over which deep sea organisms coloize new volcanic terrain the types and quantities of volcanic gasses that enter the ocean at eruption sites the types of complex organi...