Undersea Features has 16 Holocene volcanoes. Note that as a scientific organization we provide these listings for informational purposes only, with no international legal or policy implications. Volcanoes will be included on this list if they are within the boundaries of a country, on a shared boundary or area, in a remote territory, or within a maritime Exclusive Economic Zone. Bolded volcanoes have erupted within the past 20 years. Suggestions and data updates are always welcome ().

Chronological listing of known Holocene eruptions (confirmed or uncertain) from volcanoes in Undersea Features. Bolded eruptions indicate continuing activity.

Undersea Features has 2 Pleistocene volcanoes. Note that as a scientific organization we provide these listings for informational purposes only, with no international legal or policy implications. Volcanoes will be included on this list if they are within the boundaries of a country, on a shared boundary or area, in a remote territory, or within a maritime Exclusive Economic Zone. Suggestions and data updates are always welcome ().

There are 13 photos available for volcanoes in Undersea Features.

Black smoker vents emitting low-chlorinity fluids at 374°C were photographed at the "RM28" site at 18°26’S on Segment I of the Southern East Pacific Rise in November 1994 from the Japanese submersible Shinkai 6500. The narrow axial crest of Segment I of the Southern East Pacific Rise in some places is less than 50 m wide. The largest lava flow field in this area is the Animal Farm flow, named after a thriving low-temperature hydrothermal site discovered during a 1993 submersible expedition.

Image courtesy of NOAA Vents Program, 1994 (www.pmel.noaa.gov/vents/chemistry/images/). An eruption in 2005-2006 that covered 23 km² of sea floor with lava at the East Pacific Rise encased three ocean-bottom seismometers. Scientists successfully recovered two seismometers that were deployed in 2003 with the remotely operated vehicle Jason during a National Science Foundation/Woods Hole Oceanographic Institution expedition in April 2007.

Photo courtesy National Deep Submergence Facility, ROV Jason, Woods Hole Oceanographic Institution and National Science Foundation. During a 1993 ROPOS ROV (Remotely Operated Vehicle) dive on the CoAxial Segment along the Juan de Fuca Ridge a new lava flow was discovered on the sea floor. It was still hot and venting warm water (up to 50°C), and was 2.5 km long and 300 m wide. Bright yellow sediment patches indicated the presence of iron-reducing bacteria in the vent fluids. The CoAxial segment is located about 435 km W of the Oregon coast, NE of Axial volcano.

Image courtesy of National Oceanic and Atmospheric Administration (http://www.pmel.noaa.gov/vents/home.html). Detailed bathymetry of the East Gakkel Ridge at 85°E in the Arctic Ocean. The inset map shows the location of the 85°E segment (yellow star) along the Gakkel Ridge (red line). The main panel shows illuminated color bathymetry (30-m grid spacing) of the 85°E segment acquired during the AGAVE expedition. The axial valley contains large numbers of distinctive, cratered volcanoes, including a cone on a fault terrace of the northern valley wall. Named features include two volcanic ridges in the center of the axial valley (Jessica’s Hill and Duque’s Hill), and three cratered volcanoes along a ridge-parallel fissure to the south (Oden, Thor, and Loke). The bathymetry data were plotted with Generic Mapping Tools.

Sohn et al., 2008. Explosive volcanism on the ultraslow-spreading Gakkel ridge, Arctic Ocean. Nature, v. 453, p. 1236-1238. An eruption from the southern end of Axial caldera in 1998 produced this submarine lava flow that had undergone collapse, shown in this photo. Axial Seamount rises 700 m above the mean level of the central Juan de Fuca Ridge crest about 480 km W of Cannon Beach, Oregon, to within about 1.4 km of the ocean surface. The 3 x 8 km Axial caldera opens to the SE and is defined on three sides by caldera walls up to 150 m high. Hydrothermal vents colonized with biological communities are located near the caldera boundary or along the rift zones.

Photo courtesy of NOAA NeMo Observatory, 2006. The linear NE-SW-trending CoAxial Segment (center) of the Juan de Fuca Ridge is located about 435 km W of the Oregon coast. It lies NE of Axial volcano, which is in the bottom-left of this map. A submarine eruption along the CoAxial segment detected by acoustic hydrophones in June 1993 produced thermal plumes and a new lava flow. Bathymetric surveys indicated that one or more additional sea floor lava extrusions took place nearby sometime between 1981-82 and 1991.

Image courtesy of National Oceanic and Atmospheric Administration (http://www.pmel.noaa.gov/vents/home.html). Shrimp swimming above a hydrothermally active vent within basalt on the Southern East Pacific Rise (near 17° 27’ S) were photographed in November 1994 from the Japanese submersible Shinkai 6500. Shrimp and crabs were seen going in and out of similar cracks in this area. Lava flows from a recent volcanic eruption were observed in 1994 along segment K of the Southern East Pacific Rise.

Image courtesy of NOAA Vents Program, 1994 (www.pmel.noaa.gov/vents/chemistry/images/). A temperature probe from the submersible vehicle Alvin collects data at a low-temperature hydrothermal vent located in a collapse structure in the East Pacific Rise area. The maximum temperatures reached only 9.5°C. This lava flow was erupted within only a few weeks to a few months of this November 2003 expedition. The flow was covered by bacterial mats, had large amounts of bacterial floc issuing from diffuse vents, and was sparsely populated by small animals.

Photo courtesy J.R. Voight, 2003 (Ridge2000, National Science Foundation). Fluid containing precipitates rises from a "black smoker" chimney at the Tica vent at 9°N on the East Pacific Rise, photographed during a 2004 expedition sponsored by the National Science Foundation. Hot-vent animal communities (such as seen in the foreground of this image from the November to December 1989 expedition) were observed to have been buried by lava flows in 1991. Another eruption in 2005-2006 produced lava flows that covered seismometers.

Photo courtesy of Ridge2000, 2004 (http://www.ridge2000.org/eo/expeditions.php). Lava pillars supporting the upper crust remain after collapse of a lava flow that erupted from Axial volcano in 1998. The layers within the lava formed when ponded lava drained away. A seismic swarm was detected at Axial Seamount beginning on 25 January 1998. An oceanographic cruise during 9-16 February detected elevated hydrothermal plumes, and later mapping indicated that a submarine lava flow had extruded from a 9-km-long fissure system.

Photo courtesy of NOAA NeMo Observatory, 2006. Black smoker hydrothermal vents emitting high-chlorinity fluids were photographed at the "RM29" site at 18°10’S. This image was taken in November 1994 from the Japanese submersible Shinkai 6500. The axial crest of Segment J of the Southern East Pacific Rise consists of an asymmetrical shallow graben varying from 250 to 600 m wide with walls about 20 m high.

Image courtesy of NOAA Vents Program, 1994 (www.pmel.noaa.gov/vents/chemistry/images/). Axial volcano lies along the central Juan de Fuca Ridge crest about 480 km W of the Oregon coast. The summit reaches about 1.4 km below the ocean surface and is marked by a 3 x 8 km caldera (center). The caldera opens to the SE and has caldera walls up to 150 m high. Hydrothermal vents colonized with biological communities are located near the caldera boundary or along rift zones to the NE and S. In 1998 a lava flow was erupted from a fissure at the southern end of the caldera.

Image courtesy of National Oceanic and Atmospheric Administration (http://www.pmel.noaa.gov/vents/home.html). These black smoker vents are located along the Cleft Segment, the southernmost segment of the Juan de Fuca Ridge. These sustained high-temperature vents were photographed along fissures that fed an older lava flow adjacent to a 1986 lava flow that was erupted during the second of two documented submarine eruptions in the 1980s. The 80-km-long Cleft Segment is located immediately north of the Blanco Fracture Zone about 500 km off the Oregon coast.

Image courtesy of National Oceanic and Atmospheric Administration (http://www.pmel.noaa.gov/vents/home.html).

This is a compilation of Undersea Features volcano information sources, such as official monitoring or other government agencies.