In April 2006, extraordinary observations of a deep-sea explosive (Strombolian) volcanic eruption were made at NW Rota-1, a submarine volcano in the Mariana arc of the western Pacific. This research funds a return to the volcano to collect observational and analytical data and its subsequent on-shore data analysis and interpretation. Instruments including hydrophones, chemical sensors, current meters, and plume sensing devices will be deployed at the eruption site for one year. During the cruises, visual observations will made. A time-series collection of lava, gas and fluids at the active volcanic vent will also take place. Vent fluids and biological specimens from local hydrothermal vent sites will also be sampled. In terms of scientific impact, the research provides an opportunity to learn about volcanological process that have been impossible to study directly until now. Owing to the high viscosity of water, compared to air, closer and more specific observation and sampling of a Strombolian eruption can take place at Rota 1 than can be accomplished in subaerial settings. As a result, this work reveals critical proceses that help unravel eruptive mechanism of a highly destructive type of explosive volcanism. Broader impacts include public outreach via the media. The work also involves inter-Agency participation, an interdisciplinary inter-institutional collaboration, and the training a graduate student.
In 2004, NOAA scientists discovered a volcano erupting 500 m beneath the ocean surface, the first submarine eruption ever ‘caught in the act’. Even more surprising, this volcano – named Northwest Rota-1 and located about 100 km north of Guam in the Mariana Islands, western Pacific – appears to be continuously active, as verified by three oceanographic cruises and several instrument deployments between 2005 and 2010. We studied video observations and erupted samples collected during cruises in 2006, 2009, 2010. The video observations showed that they eruptions included both formation of lava flows and explosive eruptions that resemble the continuous low-level eruptive activity of Stromboli volcano, Italy. However, the pressure exerted by the overlying water column limits the explosivity of the eruptions of Northwest Rota-1, at the same time that cold seawater quenches the hot lava and breaks it into small pieces that accumulate around the eruptive vent. Most erupted samples have fewer bubbles than samples from Stromboli and other land-based volcanoes, another consequence of the water column pressure. These samples also record evidence of seawater recycling into the eruptive vent when eruption rates are low to moderate, as well as extensive dispersal of bubble-rich particles when eruption rates are high. Our work has allowed us to test theoretical models of the underwater eruptions that form the foundation of all volcanic ocean islands and to witness the processes by which ocean islands grow (and collapse). Our work has been done in collaboration with scientists studying the bathymetric, seismic/acoustic, and biological changes that accompany the growth of submarine volcanoes, and thus contributes to larger questions of marine environments and ecosystems.
