Axial Seamount on the Juan de Fuca spreading center is an optimal site for a long-term observatory. It is located just one day by ship from the Washington and Oregon coasts and it is one of the main experimental sites on the RSN. It is the most magmatically robust volcano on the spreading center, having erupted in 1998 and most recently in April 2011. It hosts numerous active hydrothermal fields and abundant sites of diffuse flow. It is one of the best-studied volcanoes along the global mid-ocean ridge spreading center and the only site where in situ pressure sensors have documented up to 13 cm/year summit inflation prior to an eruption (Nooner and Chadwick, 2009).
At Axial, a 40-km long cable installed in 2012 connects Primary Node 3A to Primary Node 3B, which is located on the southeast portion of the summit at the eastern edge of the caldera. Primary Node 3B provides power and communication to five Medium Power J-Boxes that allow access to the Ashes and International District hydrothermal vent fields and to the north central portion of the caldera. Real-time high definition video will provide unprecedented views of macrofaunal and microbial communities at the vents and chemical sensors and thermistor arrays will provide information on the environmental conditions in which the biological communities thrive. The instrumentation will also yield information on the impact of flow perturbations associated with eruptive and seismic events on biological communities. Other sensors to be installed include in situ mass spectrometers for fluid – volatile chemistry, broadband and short-period seismometers to monitor earthquake and magma migration activity, temperature and chemical probes in diffuse and black smoker sites, fluid and DNA samplers, and pressure-tilt meters for measurement of preeruptive inflation events and post eruptive deflation. The in situ DNA samplers initially will focus on in-situ filtering and preservation of time series samples in diffuse flow sites. The instrument array at Axial, which will be fully deployed and operational in 2013, is the largest single in situ experiment in the global ocean focused on long-term measurements of underwater volcanoes with transmission of real-time data and imagery back to shore.
Location: 46.1ºN 130.0ºW Water Depth: 1510-1530 meters
- 5 Medium-Power Junction Boxes
- Instruments (pdf above)