Why are eruptions in the submarine environment still poorly understood?
Direct observations of submarine lava emplacement, until recently, were limited to observations near shore where lava entered the sea from subaerial eruptions. The composition of magmas in the mantle or magma chambers have never been directly observed. Our inferences, therefore, are predominantly made from observations and samples of older, inactive flows and vents. Submarine volcanic eruptions now have been witnessed. Scientists using the ROV Ropos to study the subduction-arc volcanoes of the Northern Mariana Islands in April 2004 dove into “Brimstone Pit”, where they were engulfed in billowing, sulfurous smoke. They returned to the area in spring 2006 and witnessed red-hot rock erupting, the first such observation. In May 2009 an expedition to the back-arc spreading center in the Lau Basin observed and mapped the West Mata eruption.
