EPR 4-D seismic

We aim to address the evolution of fast-spreading mid-ocean ridge magmatic systems, focusing on decadal changes in the magma lens properties taking place from one seafloor eruption to the next one. The 9°50’N segment of the East Pacific Rise (EPR) hosts a volcanically-active system which erupted in 1991 and in 2005-06. The decadal interval between volcanic episodes provides a unique opportunity for multidisciplinary studies of magmatic, hydrothermal, and ecological cycles on human timescales. Following the 2005-06 eruption, a 3-D seismic reflection dataset was acquired in 2008 using RV Langseth, providing a new understanding of the structure of the EPR magmatic system including unprecedented detailed 3-D images showing that the axial magma lenses are corrugated with elongated ridges and troughs from where dikes nucleate. Since the 2005-06 eruption, in-situ vent temperature observations indicate the system is approaching the end of a volcanic cycle. Rising hydrothermal exit-fluid temperatures suggest that a seafloor eruption and/or diking event could occur in the mid-2020s. We propose to investigate decadal evolution of a MOR magmatic system at the EPR by conducting a repeat of the 2008 3-D seismic survey for 4-D (time-lapse) monitoring. The survey will use the 3-D multi-streamer capabilities of R/V Marcus Langseth.