AXIAL SEAMOUNT, NE PACIFIC OCEAN
Meet Axial Volcano, the Northeast Pacific Ocean's most active deep-sea volcanic center 500 km off the US West Coast.
3D rendered seafloor bathymetry of Axial Seamount (image center). Summit at ~1400m below sea level.
Did you know that the vast majority of volcanic activity on our planet actually occurs on the seafloor?!
The study of deep-sea volcanism has been rapidly increasing over the last few decades due to: access to more research vessels, improved submersible technology, better geophysical surveying methods, and even the installation of monitoring observatories on the seafloor!
Axial Volcano is one system that has benefited from ALL of these research advances.
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| 3D rendered seafloor bathymetry of Axial Seamount (image center). Summit at ~1400m below sea level. |
The study of deep-sea volcanism has been rapidly increasing over the last few decades due to: access to more research vessels, improved submersible technology, better geophysical surveying methods, and even the installation of monitoring observatories on the seafloor!
Axial Volcano is one system that has benefited from ALL of these research advances.
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| Overview of Axial Seamount (from Wilcock et al., 2018) |
GEOLOGIC SETTING
Axial is located ~300 miles off the west coast of the US, where the Pacific plate is moving northwest and the Juan de Fuca plate is moving east (thus subducting beneath North America). The seamount is located along the Juan de Fuca Ridge, a mid-ocean ridge volcanic system. But wait! Axial is ALSO located at the very southeastern end of the Cobb-Eickelberg Seamount chain (like the Hawaiian islands), which means that it is also a hot spot volcano!
So, while Axial Volcano is located within a mid-ocean ridge, it is also the youngest and most active seamount of the Cobb-Eickelberg system. Axial Volcano is the paramount location to understand the complex dynamics of seamounts. It is continuously monitored for volcanic activity and earthquakes through the installation of underwater cabled observatory. It is also intensely researched for magma chemistry, specialized volcanic and hydrothermal vent ecology, and geologic changes associated with eruptions. Axial Volcano is the whole package!
So, while Axial Volcano is located within a mid-ocean ridge, it is also the youngest and most active seamount of the Cobb-Eickelberg system. Axial Volcano is the paramount location to understand the complex dynamics of seamounts. It is continuously monitored for volcanic activity and earthquakes through the installation of underwater cabled observatory. It is also intensely researched for magma chemistry, specialized volcanic and hydrothermal vent ecology, and geologic changes associated with eruptions. Axial Volcano is the whole package!
The volcano itself is a U-shaped caldera (8 x 3km across) that is ~1000 meters taller than the seafloor on either side. The summit sits ~1400m below sea level and the volcano has two rift zones to the North and South (NRZ and SRZ) that extend many miles from the volcano. These rift zones are similar to those seen on many hotspot volcanic islands (e.g. Hawai'i) and eruptions can occur at the summit or along these rift zones.
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| The OOI Cabled Array at Axial (from Wilcock et al., 2018) |
THE AXIAL UNDERWATER VOLCANO OBSERVATORY
Axial volcano is the most volcanically active site of the northwestern Pacific and it has been continuously monitored through two complete eruption cycles, with an increased number of seafloor instruments, leading in 2014 to the deployment of a permanent, real-time, wired-to-shore, seafloor observatory that is the result of an international collaborative effort involving the National Science Foundation’s (NSF) Ocean Observatory Initiative (OOI) and Ocean Networks Canada.
The OOI seafloor observatory has monitored Axial volcano in real-time. A variety of sensors, deployed on top of the volcano, are part of this unique infrastructure, including: seismometers to monitor earthquake activity, hydrophones, in situ mass spectrometers, temperature and chemical probes, fluid and DNA samplers, stereo high definition cameras to observe rich biological communities at the vents, pressure-tilt meters, as well as a full water-column mooring with profiling capabilities and additional chemical and physical sensors [e.g., Kelley et al., 2014].
The OOI seafloor observatory has monitored Axial volcano in real-time. A variety of sensors, deployed on top of the volcano, are part of this unique infrastructure, including: seismometers to monitor earthquake activity, hydrophones, in situ mass spectrometers, temperature and chemical probes, fluid and DNA samplers, stereo high definition cameras to observe rich biological communities at the vents, pressure-tilt meters, as well as a full water-column mooring with profiling capabilities and additional chemical and physical sensors [e.g., Kelley et al., 2014].
RECENT VOLCANIC ACTIVITY
Axial Volcano has been monitored quasi-continuously for two complete eruption cycles, resulting in the successful forecasting of the latest 2015 eruption from the deployment of the full OOI less than a year before! The most recent eruptions at Axial volcano occurred in 1998, 2011 and 2015, with the eruptions corresponding very well to cycles of volcanic deformation, i.e., the volcano inflating continuously in the lead up to eruption, and then very rapidly deflating as magma evacuates the subsurface and erupts out onto the seafloor. These regular deformation cycles can potentially be used to predict future eruptions at Axial Volcano!
Lava flows produced during 1998 and 2011 were primarily confined to the summit at the South end of the caldera, whereas the lava flows in 2015 erupted mostly along the North Rift Zone (and in the northern part of the caldera). A better understanding of where magma is stored within the volcano, through a combination of geophysics and geochemistry, can also assist us in thinking about if, and where, future eruptions will occur on the volcano.
Lava flows produced during 1998 and 2011 were primarily confined to the summit at the South end of the caldera, whereas the lava flows in 2015 erupted mostly along the North Rift Zone (and in the northern part of the caldera). A better understanding of where magma is stored within the volcano, through a combination of geophysics and geochemistry, can also assist us in thinking about if, and where, future eruptions will occur on the volcano.
With plenty of prior research, frequent recent eruptions, and continuous real-time monitoring, Axial Volcano really is one of the best locations in the world to study deep-sea volcanology!
You can find out more about Axial from the following sites:
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