Axial Caldera PN-3B

Axial Caldera Science Site PN3B
Axial Caldera Instrument Table PN3B

PDF: Description of instruments now installed at Axial Caldera and connected to Primary Node PN3B.

A New Era For Submarine Volcanic Observatories

This invited review paper (by Kelley, Delaney, and Juniper) for the 50th Anniversary Volume for Marine Geology provides an overview of Axial Seamount and the Endeavour Segment of the Juan de Fuca Ridge, with emphasis on cabled observatory science that is/will be conducted at these two different volcanoes: Axial the most magmatically robust volcano on the Juan de Fuca Ridge, and the Endeavour Segment, one of the most hydrothermally active areas known in the global ocean.

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 Cabled Array. It is the most magmatically robust volcano on the spreading center, having erupted in 1998, 2011, and again April 24, 2015. It hosts numerous active hydrothermal fields and abundant sites of diffuse flow (Kelley et al., 2014). It is the most advanced volcanic observatory in the worlds' oceans.

On August 8, 2014, all secondary infrastructure (cables, junction boxes and instruments) were connected to Primary Node PN3B.  The node 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 Central and Eastern Caldera Site. Real-time high definition video now streaming to shore provides unprecedented views of macrofaunal and microbial communities at the vents.  Chemical sensors and thermistor arrays are providing real-time information on the environmental conditions in which the biological communities thrive. The instrumentation will also new insights on the impact of flow perturbations associated with eruptive and seismic events on biological communities. Other sensors now installed include an situ mass spectrometer 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.  The in situ DNA sampler is initially focused on in-situ filtering and preservation of time series samples in the El Gordo diffuse flow site.

The broadband and short-period seismometers detected >8000 earthquakes marking the start of the April 24, 2015 eruption and real-time data flow from bottom pressure-tilt meters documented live the collapse of the volcanoes caldera in 24 hrs during this same period. The instrument array at Axial, now fully installed, 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. Seismic data are now available through IRIS (over 700 users have now accessed these data), live inflation and deflation plots are provided by W. Chadwick at OSU-NOAA-PMEL, and other instrument data is available through the OOI Data Portal.

Location: 46.1ºN  130.0ºW         Water Depth: 1510-1530 meters