Collaborative Research: ELUCIDATING CONDUIT, ERUPTION AND PYROCLAST TRANSPORT DYNAMICS OF LARGE SILICIC SUBMARINE ERUPTIONS

University Of Hawaii, Honolulu

Investigators

Abstract

There are tens of thousands of volcanoes on the ocean floor. It is not known how many of these are erupting at any given time because most are overlain by many hundreds to thousands of feet of water that prevent the escape of eruption products into the atmosphere or onto the sea surface where they can be spotted by ships, airplanes, or satellites. Similarly, it is not known how many of these undersea volcanoes erupt explosively, generating large quantities of ash and pumice that is then distributed by currents or cause volcanic slope instabilities that can result in tsunamis. Because seafloor eruptions, in particular those that are explosive in nature, are hidden from view, our knowledge of how they operate, their eruption products and their distribution, and their geohazard potential is almost unknown. Luckily in July 2012, a 200 square kilometer raft of pumice was spotted floating on the ocean in the western Pacific just above Havre Volcano which is under 1600 meters of water, indicating a major explosive eruption. Taking advantage of this event, this project mounts a major scientific investigation of the eruption. The research involves a comprehensive physical and chemical study of the volcano, the eruption, and the associated eruption products and their distribution near and far from their point of origin. Through an oceanographic cruise using state-of-the-art robotic vehicles, the investigators will collect samples and sediment cores and create seafloor photo mosaics of the area. The research also involves high resolution seafloor mapping and stratigraphic analysis of the related deposits in the vicinity of the volcano and in areas extending away from it. Investigators will compile and analyze all available photographic images, pre- and post-eruptive seafloor maps, as well as analyze sediment cores and ash textures. The project also includes analysis and interpretation of stratigraphic, geochemical, and other associated datasets. A specific focus of the research is determining the role that volatiles such as H2O, SO2, and sulfur played in the eruption. Goals of the research are to determine: (1) what combination of magma ascent rates and conduit processes caused the formation of a subaerial eruption plume from water depths of more than 1600 m; (2) if the data can shed light on the outstanding controversy regarding the lack of fine ash in deposits now found on land but that were derived from subaqueous eruptions; and (3) whether density currents that result from eruption column collapse are the primary transport mechanism for mass sediment flux away from the volcano or if other processes dominate. Broader impacts of the research include significant undergraduate training in research and state of the art field and laboratory scientific techniques, as well as cross training and video presentations that will link together all of the researchers and students at the institutions involved. Additional impacts include international collaboration with New Zealand scientists and the creation of a new, international body to study submarine volcanoes and the impacts of their explosive eruption. Also included are presentations to local community groups and K-12 schools, impacts for geohazards and disaster planning, support of an institution in an EPSCoR state, and support of an early career investigator whose gender is under-represented in the sciences and engineering.