Axial Seamount is a volcanic hot-spot interacting with the Juan de Fuca mid-ocean ridge, and located a day’s steam (about 250 nautical miles) from the Oregon coast. The summit reaches to about 1400 m below the sea surface on the rim of a 100-m deep caldera, and rift zones extend 50 km to the north and south and drop to almost 2500 m depth. The Submarine Volcanism Group began making dives at Axial with the ROV Tiburon in 2005, and the first Mapping AUV surveys there were in 2006. Meter-scale AUV bathymetry together with ROV-collected samples and observations have enabled the construction of the geologic history of the volcano, which has experienced over 50 eruptions in the past 1600 years. Three of those eruptions occurred since Axial was discovered: in 1998, 2011, and 2015. Subtracting pre-eruption bathymetry from post-eruption bathymetry reveals the fissures, channel systems and extents and volumes of the flows. Coupling data from instruments deployed in the caldera as part of the Ocean Observing Initiative (OOI) with the bathymetry allows calculation of eruption rates and growth patterns of flow lobes. Differencing the bathymetry from repeated AUV survey lines across the edifice reveals the deformation of the volcano the magma chamber prior to its next eruption. Centimeter-scale mapping with the Low-Altitude Survey System of several of Axial’s hydrothermal vent fields allows assessment of OOI infrastructure, hydrothermal chimney deposits, microbial mats, and chemosynthetic animal communities living in areas of both vigorous and diffuse venting.

A small portion of the Axial 2011 flow is depicted in this map of the difference between before and after bathymetry from MBARI’s Mapping AUV. Eruptive fissures are visible at right, flow channels in the middle, and inflated flow margins at left and lower middle. Color ramp (blue to orange) is 0 to 15 m flow thickness, vertical precision is 0.2 m, horizontal resolution is 1 m, and the area shown is about 2×3 km.
Oblique view of a map of the summit of Axial Seamount looking north with 2X vertical exaggeration.



Le Saout, M., D.R. Bohnenstiehl, J.B. Paduan, and D.A. Clague. 2020. Quantification of eruption dynamics on the north rift at Axial Seamount, Juan de Fuca Ridge. Geochemistry, Geophysics, Geosystems, 21: 1–11.

Clague, D.A., J.B. Paduan, D.W. Caress, W.W. Chadwick Jr., M. Le Saout, B. Dreyer, and R.A. Portner. 2017. High-resolution AUV mapping and targeted ROV observations of three historical lava flows at Axial Seamount. Oceanography, 30: 82–99.

Chadwick, W.W., J.B. Paduan, D.A. Clague, B.M. Dreyer, S.G. Merle, A.M. Bobbitt, D.W. Caress, B.T. Philip, D.S. Kelley, and S.L. Nooner. 2016. Voluminous eruption from a zoned magma body after an increase in supply rate at Axial Seamount. Geophysical Research Letters, 43: 12063–12070.

Clague, D., B.M. Dreyer, J.B. Paduan, J.F. Martin, W.W. Chadwick, D.W. Caress, R.A. Portner, T.P. Guilderson, M.L. McGann, H. Thomas, D.A. Butterfield, and R.W. Embley. 2013. Geologic history of the summit of Axial Seamount, Juan de Fuca Ridge. Geochemistry, Geophysics, Geosystems, 14: 4403–4443.

Caress, D.W., D.A. Clague, J.B. Paduan, J.F. Martin, B.M. Dreyer, W.W. Chadwick Jr., A. Denny, and D.S. Kelley. 2012. Repeat bathymetric surveys at 1-metre resolution of lava flows erupted at Axial Seamount in April 2011. Nature Geoscience, 5: 483–488.