The July 13 ROPOS Dive 1603 marked the start of laying cable at the summit of Axial Seamount. The first cable chosen was a “short” 600 m (~1800 ft) run from Primary Node 3B southward to a site called Eastern Caldera. This site is important because next year it will host a suite of cabled instruments that will provide real-time data on earthquakes inside the volcano, more distal earthquakes, and on inflation and deflation of the volcano. Similar to terrestrial volcanoes, basaltic melt and gases (e.g., carbon dioxide) build up within the core of Axial causing the top and sides of the volcano to deform (inflate and tilt). Past results from bottom-pressure tilt meters, developed by Bill Chadwick at NOAA PMEL, indicate that the summit of the volcano inflated gradually during the months leading up to a large eruption that occurred at Axial Volcano on April 6, 2011. During the three months prior to the eruption, the seafloor rose ~ 1.5 feet, which is extremely rapid for geological processes. These changes, coupled with thousands of small earthquakes, are strong precursors of seafloor eruptions. With enough data, such as that provided in real-time by the cabled observatory starting next summer, it may be possible in the future to forecast when a submarine eruption may occur.
Today cable laying went smoothly, and ROPOS returned to the surface near midnight. Upon recovery, preparations immediately commenced to prepare another ROCLS drum hosting over 15,000 feet of cable to be deployed for installation of another geophysical suite of instruments in the central part of the caldera.