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Axial Seamount AXIAL SEAMOUNT - WIRED AND RESTLESS: A Cabled Submarine Network Enables Real-time, Tracking of a Mid-Ocean Ridge Eruption and Live Video of an Active Hydrothermal System Juan de Fuca Ridge, NE Pacific John R. Delaney1, Deborah S. Kelley1, Aaron Marburg2, Kim Juniper3 and Friedrich Knuth4 Mark Stoermer1, and Hunter Hadaway1, University of Victoria3 Ocean Networks Canada,Victoria School of Oceanography1 and Applied Physics B.C., Canada; 4 Rutgers University, Department of Marine Laboratory2 University of Washington and Coastal Sciences, New Brunswick, Seattle, WA, 98195 New Jersey Abstract—The most scientifically diverse and technologically understood owing to their remote locations beneath one to four advanced component of the National Science Foundations’ kilometers of seawater. As a consequence, submarine volcano- $386M investment in the Ocean Observatories Initiative (OOI), hydrothermal systems have never been observed-monitored involves 900 kilometers of high power and bandwidth electro- continuously. Nor have their immediate effects on overlying optical cable extending from Pacific City, OR, across active marine ecosystems been assessed because they are most active portions of the Juan de Fuca tectonic plate and up into the just before, during, and shortly after unpredictable eruptions overlying ocean. Completed on time and under budget in when the systems are the most energetic. Tracking the long- October, 2014, this mesoscale fiber-optic sensor array enables term behavior of even a small section of this powerful real-time, high-bandwidth, 2-way communication with seafloor planetary-scale submarine MOR could contribute substantially and water-column sensor networks across: 1) a portion of the to our understanding of a host of complex oceanic processes global Mid-Ocean Ridge (MOR), 2) a section of the Cascadia Subduction Zone, and, 3) a cross-section of the California triggered by numerous eruptions along this global submarine Current, a component of the North Pacific Gyre. Much of the volcanic system. data generated from >130 fiber-linked instruments has become The concept of the Cabled Observatory was significantly available for scientific, educational and public user communities refined early in its development when the National Science over the past 6 to 12 months, via the OOI Cyber-infrastructure Foundation (NSF) issued a “Request for Assistance” to the (http://oceanobservatories.org/data-portal/). Since the OOI ocean science community for proposals focused on the Cabled System has been in use and streaming live data to shore, research that could be done with new 25-year duration cabled two major developments have emerged that bear on undersea and uncabled observatories with funds from NSF’s volcano-hydrothermal systems: 1) The 2015 submarine eruption of Axial Seamount was documented in a unique fashion by 20 transformative Major Research Equipment Facility remote, hardwired instruments distributed across the floor of the Construction award. This call resulted in an outpouring of summit caldera. 2) Live, streaming video of an active enthusiasm in the form of 16 proposals focused on a cabled hydrothermal system within one of the vent fields inside the system in the NE Pacific (then called NEPTUNE: Northeast caldera reveals subtle changes taking place in the Axial system. Pacific Time-Series Underwater Networked Experiments). For more than 1.5 decades, multiple community meetings, Keywords— Mid-Ocean Ridge Systems; volcanic eruptions; workshops, and a series of multi-author science hydrothermal venting; OOI; seismic and geodetic studies; electro- recommendations for design requirements based on strong optical networks; real-time; interactive science at high bandwidth community consensus emerged favoring the cabled approach to ocean science [1-9]. As an important result of this process, I. INTRODUCTION Axial Seamount on the Juan de Fuca Ridge was chosen as a The Mid-Ocean Ridge (MOR) system extends around the key study site for implementation of the first major U.S. world as a highly active 65,000 km-long submarine volcanic supported Cabled Observatory focused on an active MOR mountain chain present in every ocean basin. It is adding spreading center with associated hydrothermal fields and oceanic crust to bounding plates along a global volcanic diverse faunal assemplages [10]. mountain chain. Indeed, estimates indicate this network Axial Seamount (Fig. 1) is a highly active MOR volcano accounts for 70% of the volcanism on Earth. Although most of located along the Juan de Fuca (JdF) spreading center between the oceanic crust on Earth is generated by eruptions along the the Pacific and JdF tectonic plates. It spans the intersection of a MOR system, interactions between the submarine volcanic segment of the Jdf ridge with the present location of the Cobb- activity and overlying oceanic ecosystems are poorly Fig. 1. Overview of the Juan de Fuca (JdF) Plate off the coast of WA-OR with an inset of Axial Seamount, a hot spot-influenced volcano perched on the JdF spreading center, a portion of the mid-ocean ridge network. Axial Caldera, at the summit of the volcano, is 3 x 7 km and lies along the trace of the spreading center. Location of the Primary Node 3B (PN3B) of the OOI Cabled Array is near the edge of the active caldera. Eickelberg Hot Spot [11]. For this reason, Axial Seamount hydrothermal systems to define diversity, and productivity, stands well above the surrounding seafloor and the ridge crest, temporal and spatial evolution in response to changing owing to the excess magma supply fueled by combined ridge environmental conditions. crest and hot spot magmatism. The summit caldera is a 3 km x 7 km depression at a water depth of ~1500 m and it is bisected II. THE CABLED ARRAY by the JdF, with a spreading rate of ~6 cm per year. The With the successful installation and now two years caldera is is underlain by a robust ~ 1 km thick melt body that operation of the cabled component of the National Science extends ~ 14 km in length and is 3 km wide beneath the caldera Foundations’ Ocean Observatories Initiative (OOI), national [12]. and international scientific and educational communities now Goals focused this spreading system included development have opportunities to continuously assess technologies never with the intention to: before available [10,13]. The Axial infrastructure is a key component of the Cabled Array as a whole, which includes 900 •Characterize and quantify the immediate biological, km of fiber optic cable that hosts seven Primary Nodes, each chemical and geological consequences of transient events such providing 8 kW power and 10 Gbs bandwidth to seafloor and as dike intrusions, eruptions, and deformation events associated water column sites along the array. The high power and high with seafloor spreading; bandwidth electro-optical cables on the Cabled Array connect a potentially large and diverse shore-side user base with 140 •Make direct long-term measurements of seafloor inflation geophysical, chemical, and biological sensors across the with concomitant seismic and hydrothermal volatile tectonic plate and up into the overlying water-column [10,13]. measurements, to eventually be able to predict seafloor This system provides two-way communication at the speed of eruptions; light, interactive mission execution, and rapid event response •Quantify temperature, chemical, and biological parameters that may include changing sampling rates, profiling missions, within the complex hydrothermal/eruptive effluent (then called and look angles of cameras. At its most basic level, it brings “mega-plumes”); the Internet into the ocean for 24/7/365 observations at full sampling rates on all systems including high definition video. •Begin over the long-term to quantify heat and chemical Operation and monitoring of the status and health of the system fluxes from MOR Systems; and is managed by the University of Washington. •Make long-term, co-regisered measurements of biological Key portions of Axial are now uniquely instrumented and communities in, around and above active volcano- connected to the Internet via a network of electro-optical cables Fig. 2. View of the instrumented caldera at the summit of Axial Seamount, a highly active mid-ocean ridge volcanic edifice. A high-definition video camera (CAMHD) is located in the ASHES Vent Field near the west wall of the caldera (red circle). The camera is trained on the actively venting edifice called Mushroom that hosts dense macro- and microbial assemblages: here HD video has been streaming live every 3 hours, day and night, for the past 12 months. extending more than 400 kilometers back to Pacific City, OR. interacting systems on a global scale. The OOI Cabled Array is Primary Node PN3B, near the east edge of the volcano’s a major new facility in the oceanographers tool box for in- summit, is supporting more than 38 km of extension cables depth study of these and other such dynamic multi-parameter distributed across the floor of the Axial Caldera (Fig. 2). This subsea systems. volcanically centered sensor network now provides real-time, interactive network connectivity and power between shore-side III. TRACKING A SUBMARINE MID-OCEAN RIDGE ERUPTION researchers and data streaming from tens of seafloor and water- FROM SHORE column instruments located on and near Axial Seamount. In late April, 2015, the array of sensors at Axial captured For the first time, a highly active portion of the global the seismicity, deformation, and temperature changes MOR system has been
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