Bowie Seamount

Bowie Seamount is a large submarine volcano in the northeastern Pacific Ocean, located 180 km (110 mi) west of Haida Gwaii, British Columbia, Canada.

The seamount is also known as Bowie Bank. In the Russian language, Bowie is called Гора Бауи (Gora Baui), which literally means Mount Bowie.[3] In Haida language it is called SG̱aan Ḵinghlas, meaning Supernatural One Looking Outward.[4][5] It is named after William Bowie of the U.S. Coast and Geodetic Survey.[6]

The volcano has a flat-topped summit rising about 3,000 m (10,000 ft) above the seabed, to 24 m (79 ft) below sea level.[1] The seamount lies at the southern end of a long underwater volcanic mountain range called the Pratt-Welker or Kodiak-Bowie Seamount chain, stretching from the Aleutian Trench in the north almost to Haida Gwaii in the south.[1]

Bowie Seamount lies on the Pacific Plate, a large segment of the Earth's surface which moves in a northwestern direction under the Pacific Ocean. It is adjacent to two other submarine volcanoes; Hodgkins Seamount on its northern flank and Graham Seamount on its eastern flank.

Bowie Seamount
Bowie Seamount map
Map of Bowie Seamount
Bowie Seamount1
3-D depiction of Bowie Seamount
Summit depth24 m (79 ft)[1][2]
Height~3,000 m (9,843 ft)
LocationNorth Pacific Ocean, 180 km (112 mi) west of the Haida Gwaii
Coordinates53°18′24.93″N 135°39′33.23″W / 53.3069250°N 135.6592306°WCoordinates: 53°18′24.93″N 135°39′33.23″W / 53.3069250°N 135.6592306°W
TypeSubmarine volcano
Volcanic arc/chainKodiak-Bowie Seamount chain
Age of rockPleistocene
Last eruption18,000 years ago[2]



Seamounts are volcanic mountains which rise from the seafloor. The unlimited supply of water surrounding these volcanoes can cause them to behave differently from volcanoes on land. The lava emitted in eruptions at Bowie Seamount is made of basalt, a common gray to black or dark brown volcanic rock low in silica content (the lava is mafic). When basaltic lava makes contact with the cold sea water, it may cool very rapidly to form pillow lava, through which the hot lava breaks to form another pillow. Pillow lava is typically fine-grained, due to rapid cooling, with a glassy crust, and has radial jointing.[7]

With a height of at least 3,000 m (10,000 ft) and rising to within only 24 m (79 ft) of the sea surface, Bowie Seamount is the shallowest submarine volcano on the British Columbia Coast, as well as in Canadian waters, and one of the shallowest submarine volcanoes in the northeast Pacific Ocean.[1][2] Most seamounts are found hundreds to thousands of metres below sea level, and are therefore considered to be within the deep sea. In fact, if Bowie Seamount were on land it would be about 600 m (2,000 ft) higher than Whistler Mountain in southwestern British Columbia and 800 m (2,600 ft) lower than Mount Robson, the highest mountain in the Canadian portion of the Rocky Mountains.[2]

Bowie Seamount is about 55 km (34 mi) long and 24 km (15 mi) wide.[2] Its flat-topped summit is made of weakly consolidated tephra and consists of two terraces.[2][8] The lowest terrace is about 230 m (750 ft) below sea level while the highest is about 80 m (260 ft) below sea level, but contains steep-sided secondary summits that rise to within 25 m (82 ft) below sea level. From a physical perspective, the effective size of the submarine volcano is considerably large. The effects of other submarine volcanoes along the Pacific Northwest, including Cobb Seamount off the coast of Washington, can be noticed in the composition and abundance of the tiny floating organisms called plankton up to 30 km (20 mi) away from the seamount summit. Because of its similar size, Bowie Seamount most likely has a similar effect on its adjacent waters.[2]

Eruptive history

Hodgkins and Bowie
3-D depiction of Hodgkins Seamount with Bowie Seamount in the background

Bowie Seamount was formed by submarine eruptions along fissures in the seabed throughout the last glacial, or "Wisconsinian", period, which began about 110,000 years ago and ended between 15,000 and 10,000 years ago. While most submarine volcanoes in the Pacific Ocean are more than one million years old, Bowie Seamount is relatively young. Its base was formed less than one million years ago, but its summit shows evidence of volcanic activity as recently as 18,000 years ago.[2] This is recent in geological terms, suggesting the volcano may yet have some ongoing volcanic activity.[1]

Close to Bowie's submerged summit, former coastlines cut by wave actions and beach deposits show that the submarine volcano would once have stood above sea level, as either a single volcanic island or as a small cluster of shoals that would have been volcanically active. Sea levels during the last glacial period, when Bowie Seamount was formed, were at least 100 m (300 ft) lower than they are today.[1][2] It would have had a land area similar to, if not larger than, Midway Atoll in the central Pacific Ocean.

Kodiak-Bowie Seamounts
Map of the Kodiak-Bowie Seamount chain


There is some disagreement about the origin of Bowie seamount: Geological studies indicate that the Kodiak-Bowie Seamount chain may have formed above a center of upwelling magma called a mantle plume. The seamounts comprising the Kodiak-Bowie Seamount chain would be formed above the mantle plume and carried away from the mantle plume's magmatic source as the Pacific Plate moves in a northwesterly direction towards the Aleutian Trench, along the southern coastline of Alaska.[9]

The volcanic rocks which make up some of the seamounts in the Kodiak-Bowie Seamount chain are unusual in that they have an acid-neutralizing chemical substance like typical ocean-island basalts but a low percentage of strontium as found at mid-ocean ridge basalts. However, the strontium-bearing volcanic rocks comprising Bowie Seamount also contain lead. Therefore, the magma mixtures that formed Bowie Seamount seem to have originated from varying degrees of partial melting of a depleted source in the Earth's mantle and basalts which had distinctly high lead isotopic ratios. Estimates during geological studies indicate that the abundance of the depleted-source component ranges from 60 to 80 percent of the erupted material.[9]

Some aspects of the origin of the Kodiak-Bowie Seamount chain remain uncertain. The volcanic rocks found at the Tuzo Wilson Seamounts south of Bowie are fresh glassy pillow basalts of recent age, as would be expected if these seamounts are located above or close to a mantle plume south of Haida Gwaii. However, the origin of Bowie Seamount is less certain because even though the seafloor which Bowie lies on formed 16 million years ago during the late Miocene period, Bowie's summit shows evidence of recent volcanic activity. If Bowie Seamount formed above a mantle plume at the site presently occupied by the Tuzo Wilson Seamounts, it has been displaced from its magma source by about 625 km (390 mi) at a rate of about 4 cm (2 in) per year. The geologic history of Bowie Seamount is consistent with its flat-topped eroded summit, but the source for Bowie's recent volcanic activity remains uncertain.[9] Still others, such as Dickens Seamount and Pratt Seamount further north of Bowie Seamount, fall a little to the side of the chain's expected trend.[10] Another hypothesized origin of some or all seamounts in the Kodiak-Bowie Seamount chain is that they formed on top of the Explorer Ridge, a divergent tectonic plate boundary west of Vancouver Island, and have been displaced from it by seafloor spreading.[9]

Although some of the seamounts in the Kodiak-Bowie Seamount chain appear to follow the expected age progression for a mantle plume trail, others, such as Denson Seamount, are older than that hypothesis would suggest.[10] As a result, the Kodiak-Bowie Seamount chain has also been proposed by geoscientists to be a mix of ridge and mantle plume volcanism.


Haida Heritage Centre
Haida Heritage Centre at Kaay Llnagaay where the Bowie Seamount Marine Protected Area was announced

Bowie Seamount supports a biologically rich area with a vigorous ecosystem. Studies have recorded high densities of crab, sea stars, sea anemones, sponges, squid, octopus, rockfish, halibut and sablefish. Eight species of marine mammal have been found in the Bowie Seamount area, including Steller sea lions, orca, humpback and sperm whales, along with 16 varieties of seabirds.[11] This has made Bowie Seamount a rare habitat in the northeast Pacific Ocean and one of the most biologically rich submarine volcanoes on Earth.[1][12] The rich marine life is due to the intense food supply of microscopic animals and plants, including phytoplankton and zooplankton.[13]

Bowie Seamount Marine Protected Area

Because of its biological richness, Bowie Seamount was designated as Canada's seventh Marine Protected Area on April 19, 2008 under the Oceans Act and has been described as an "Oceanic Oasis".[11] The announcement was made by federal Fisheries Minister Loyola Hearn and Guujaaw, President of the Council of the Haida Nation, in Skidegate on Haida Gwaii (formerly called the Queen Charlotte Islands). During the announcement, Natural Resources Minister Gary Lunn said: "Bowie Seamount is an oceanic oasis in the deep sea, a rare and ecologically rich marine area, and our government is proud to take action to ensure it is protected. By working in partnership with the Council of the Haida Nation and groups like the World Wildlife Fund-Canada, we are ensuring this unique treasure is preserved for future generations."[12] It measures about 118 km (73 mi) long and 80 km (50 mi) wide, totaling an area of 6,131 km2 (2,367 sq mi).[13] This is the northernmost of the two Marine Protected Areas on the British Columbia Coast; the southernmost is the Endeavour Hydrothermal Vents, an active hydrothermal vent zone of the Juan de Fuca Ridge 250 km (160 mi) southwest of Vancouver Island.[14] The Bowie Seamount Marine Protected Area also includes Peirce Seamount (also called Davidson Seamount) and Hodgkins Seamount.[12]

Diving explorations and studies

The shallow depth of Bowie Seamount makes it the only underwater mountain off the British Columbia Coast easily reached using scuba diving equipment. In March 1969, dives were made at the submarine volcano by Canadian Forces Maritime Command divers from the CSS Parizeau. Two dives were made to the summit where monochrome photographs were taken to record the environment and some biological samples were gathered to detect possible harmful plants, animals, or bacteria. These specimens were identified at the Pacific Biological Station in Nanaimo, creating a list of eleven varieties of sea bottom invertebrates.[8]

Bowie Seamount2
Eastern flank of Bowie Seamount

In August 1969, Canadian Forces Maritime Command divers made more dives during scientific studies by the Fisheries Research Board of Canada. They found very dense shoals of rockfish floating over Bowie's flat-topped summit and a variety of bottom life. A number of monochrome photographs were taken and a few seaweeds were collected, but no species record was created for other types of oceanic life around Bowie Seamount.[8]

In November 1996, an issue of the National Geographic Magazine included an article titled "Realm of the Seamount", describing dives made at Bowie Seamount by two explorers named Bill Curtsinger and Eric Hiner. They explored the slopes of Bowie Seamount using scuba diving equipment down to 150 m (490 ft). Their photographs featured one of Bowie's rugged peaks thickly covered with seaweeds and colourful sea bottom invertebrates. Shoals of young rockfish were seen on Bowie's steep flanks.[8]

Scientist Bill Austin of Khoyatan Marine Lab in the Northeast Pacific examined a video made during the National Geographic dives to identify the benthic flora and fauna of Bowie Seamount. From the video, Austin recognized some of the most noticeable invertebrates and noted that a few species generally occurring in the intertidal zone and in shallow subtidal environments were found deeper than might normally be expected, and were bigger than normal.[8]

A team of five divers, led by photographer/videographer Neil McDaniel, visited the seamount August 3–5, 2003 and conducted a biological and photographic survey of the summit down to depths of about 40 m (130 ft). A total of 18 taxa of algae, 83 taxa of conspicuous invertebrates and 12 taxa of fishes were documented, approximately 180 underwater still photographs were taken and approximately 90 minutes of digital video were recorded. Of particular note were the dense schools of rockfish hovering over the summit and numerous curious prowfish.[8]

Indigenous people

To the Haida Nation, the indigenous people who played a key role to establish the Bowie Seamount Marine Protected Area, the submarine volcano is called Sgaan Kinghlas. In their language it means "Supernatural Being Looking Outward".[12]

This seamount has long been recognized by the Haida Nation as a special place. Guujaaw, President of the Council of the Haida Nation, has said: "Sgaan Kinghlas represents a shift in recognizing the need for respect and care for the Earth. This is a very significant turning point in reversing the trends that have been leading to the depletion of life in the sea."[12]

Marine hazard

Given its shallow depth, Bowie Bank is a potential marine hazard. Waves up to 27 m (89 ft) high have been recorded along the British Columbia Coast during heavy weather, enough to expose the bank by wave troughs and cause devastation to any vessel transiting the seamount. For this reason, Environment Canada has recognized Bowie Seamount as a hazard to navigation, and it is avoided by shipping vessels.[15][16]

See also


  1. ^ a b c d e f g "Bowie Seamount Marine Protected Area Management Plan" (PDF). Fisheries and Oceans Canada. August 2001. Archived from the original (PDF) on 2009-03-24. Retrieved October 27, 2008.
  2. ^ a b c d e f g h i "The Bowie Seamount Area" (PDF). John F. Dower and Frances J. Fee. February 1999. Archived from the original (PDF) on 2009-03-24. Retrieved October 27, 2008.
  3. ^ "Marine Gazetteer Placedetails". Retrieved 2017-06-23.
  4. ^ "DFO SGaan Kinghlas-Bowie Seamount Marine Protected Area". Department of Fisheries and Oceans Canada. Retrieved 2018-01-16.
  6. ^ "Undersea Features History". GEOnet Names Server. Archived from the original on 2012-02-11. Retrieved 2012-03-07.
  7. ^ "Submarine Volcanoes, Vents, Ridges, and Eruptions". USGS. March 13, 2005. Retrieved October 27, 2008.
  8. ^ a b c d e f "Biological Observations at Bowie Seamount: August 3-5, 2003" (PDF). N. McDaniel, D. Swanston, R. Haight, D. Reid and G. Grant. October 22, 2003. Archived from the original (PDF) on 2009-03-24. Retrieved November 6, 2008.
  9. ^ a b c d Faure, Gunter (2001). Origin of Igneous Rocks: The Isotopic Evidence. Springer. pp. 66, 67. ISBN 978-3-540-67772-7.
  10. ^ a b "Seamounts in the Eastern Gulf of Alaska: A Volcanic Hotspot with a Twist?". National Oceanic and Atmospheric Administration. July 12, 2005. Retrieved October 27, 2008.
  11. ^ a b "Bowie Seamount Marine Protected Area". Fisheries and Oceans Canada. May 25, 2006. Archived from the original on 2009-03-01. Retrieved October 27, 2008.
  12. ^ a b c d e "Bowie Seamount Designated as Canada's Seventh Marine Protected Area". Fisheries and Oceans Canada. April 19, 2008. Archived from the original on September 11, 2009. Retrieved October 27, 2008.
  13. ^ a b "Designation of Bowie Seamount as a Marine Protected Area". Fisheries and Oceans Canada. October 11, 2008. Archived from the original on May 20, 2011. Retrieved October 30, 2008.
  14. ^ "Marine Protected Areas". Fisheries and Oceans Canada. March 7, 2008. Archived from the original on November 3, 2008. Retrieved November 7, 2008.
  15. ^ Prostar Sailing Directions 2005 North Pacific British Columbia Enroute. ProStar Publications. 2005. p. 259. ISBN 1-57785-658-9.
  16. ^ Canessa, R. R.; Conley, K. W.; Smiley, B. D. (2003). "Bowie Seamount Pilot Marine Protected Area: An Ecosystem Overview Report". Fisheries and Oceans Canada: 16. ISSN 0706-6457. Cite journal requires |journal= (help)

External links

Alaska Plain

The Alaska Plain, also referred to as the Alaskan Plain or Alaskan Abyssal Plain, is an oceanic basin under the Gulf of Alaska. The plain is bordered to the northwest by the Alaskan portion of the Aleutian Trench, to the north and east by the continental shelf off the coast of Alaska and British Columbia, and to the south by two separate lines of seamounts, from Patton seamount in the northwest, located just south of Kodiak Island, to Bowie seamount in the southeast, located just west of Queen Charlotte Islands, running from 54°40′N 150°30′W and 53°18′N 135°38′W.

Bowie hotspot

The Bowie hotspot is a volcanic hotspot, located 180 kilometres (110 mi) west of the Queen Charlotte Islands in the Pacific Ocean.

Almost all magma created by the hotspot has the composition of basalt, and so the volcanoes are constructed almost entirely of this igneous rock. The eruptions from the Bowie hotspot are effusive eruptions because basaltic magma is relatively fluid compared with magmas typically involved in more explosive eruptions, such as the andesitic magmas that produce some of the spectacular and dangerous eruptions around the margins of the Pacific Ocean.

Bowie hotspot is believed to be perhaps 100 to 150 km (60 to 90 mi) wide and underlain by a mantle plume that is relatively deep. It is also considerably weak.Eruptions from the Bowie hotspot have left a trail of underwater mountains across the Pacific, called the Kodiak-Bowie Seamount chain, which is an underwater mountain region of seamounts along a line beneath the northern Pacific Ocean. The oldest volcano in the chain is Kodiak Seamount with an estimated age of 24 million years and the youngest called Bowie Seamount.

Geological studies show that the base of Bowie Seamount formed less than a million years ago. The summit of Bowie Seamount is even younger and shows signs of having been active as recently as 18,000 years ago. Because of its shallow depth, some geologists believe Bowie Seamount was an active volcanic island throughout last ice age.

Denson Seamount

Denson Seamount is a submarine volcano in the Kodiak-Bowie Seamount chain, with an estimated age of 18 million years. It lies at the southern end of the chain near the Canada–United States border. It was one of the underground volcanic extrusions investigated by the 2004 Gulf of Alaska Seamount Expedition. The expedition's goal was:

"Our goal was to gain an understanding of the geologic histories of the five previously unexplored seamounts in the Gulf of Alaska. To achieve this we created a full-coverage swath bathymetry map of each seamount and its surroundings, and we collected rock samples at all possible depths." -Randy Keller, Oregon State University

On August 6, 2004, the DSV Alvin dropped down near the Denson Seamount and collected basaltic rock to try to determine the age of the seamount. The search was difficult because the salty water had altered the volcanic rock over time, but they determined in lab tests that the Denson Seamount was about 18 million years old. The team used bathymetric mapping to render three-dimensional images of the Denson Seamount and its counterparts.

Geology of the Pacific Northwest

The geology of the Pacific Northwest includes the composition (including rock, minerals, and soils), structure, physical properties and the processes that shape the Pacific Northwest region of the United States and Canada. The region is part of the Ring of Fire: the subduction of the Pacific and Farallon Plates under the North American Plate is responsible for many of the area's scenic features as well as some of its hazards, such as volcanoes, earthquakes, and landslides.

The geology of the Pacific Northwest is vast and complex. Most of the region began forming about 200 million years ago as the North American Plate started to drift westward during the rifting of Pangaea. Since that date, the western edge of North America has grown westward as a succession of island arcs and assorted ocean-floor rocks have been added along the continental margin.

There are at least five geologic provinces in the area: the Cascade Volcanoes, the Columbia Plateau, the North Cascades, the Coast Mountains, and the Insular Mountains. The Cascade Volcanoes are an active volcanic region along the western side of the Pacific Northwest. The Columbia Plateau is a region of subdued geography that is inland of the Cascade Volcanoes, and the North Cascades are a mountainous region in the northwest corner of the United States, extending into British Columbia. The Coast Mountains and Insular Mountains are a strip of mountains along the coast of British Columbia, each with its own geological history.


In marine geology, a guyot (pronounced ), also known as a tablemount, is an isolated underwater volcanic mountain (seamount) with a flat top more than 200 m (660 ft) below the surface of the sea. The diameters of these flat summits can exceed 10 km (6.2 mi). Guyots are most commonly found in the Pacific Ocean, but they have been identified in all the oceans except the Arctic Ocean.

Hodgkins Seamount

Hodgkins Seamount is a seamount in the Kodiak-Bowie Seamount chain, located south of Pierce Seamount and north of Bowie Seamount. It has apparently experienced two generically different episodes of volcanism, separated by about 12 million years. Like the rest of the Kodiak-Bowie seamounts, it was formed by the Bowie hotspot.

Hole-in-the-Wall Provincial Park

Hole-in-the-Wall Provincial Park is a provincial park west of Tumbler Ridge in British Columbia, Canada.

Hotspot (geology)

In geology, the places known as hotspots or hot spots are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle. Their position on the Earth's surface is independent of tectonic plate boundaries. There are two hypotheses that attempt to explain their origins. One suggests that hotspots are due to mantle plumes that rise as thermal diapirs from the core–mantle boundary. The other hypothesis is that lithospheric extension permits the passive rising of melt from shallow depths. This hypothesis considers the term "hotspot" to be a misnomer, asserting that the mantle source beneath them is, in fact, not anomalously hot at all. Well-known examples include the Hawaii, Iceland and Yellowstone hotspots.

Kodiak Seamount

Kodiak Seamount is the oldest seamount in the Kodiak-Bowie Seamount chain, with an estimated age of 24 million years. It lies at the northernmost end of the chain and its flat-topped summit is strewn with fault lines. Like the rest of the Kodiak-Bowie seamounts, it was formed by the Bowie hotspot.

Kodiak Seamount will eventually be destroyed by subduction by the Aleutian Trench once it is carried into the trench by the ongoing plate motion, although this will not fully occur for several million more years if the current rate of motion is maintained. Because of Kodiak Seamount's approach into the Aleutian Trench, it is literally cracking up under the stress. Although Kodiak is the oldest extant seamount in the Kodiak-Bowie chain, the adjacent lower slope contains transverse scars indicating earlier subduction of seamounts.

Kodiak–Bowie Seamount chain

The Kodiak–Bowie Seamount chain, also called the Pratt–Welker Seamount chain and the Kodiak Seamounts, is a seamount chain in southeastern Gulf of Alaska stretching from the Aleutian Trench in the north to Bowie Seamount, the youngest volcano in the chain, which lies 180 km (112 mi) west of the Queen Charlotte Islands, British Columbia, Canada. The oldest volcano in the chain is the Kodiak Seamount. Although the Kodiak Seamount is the oldest extant seamount in the Kodiak-Bowie chain, the adjacent lower slope contains transverse scars indicating earlier subduction of seamounts.

The Kodiak–Bowie Seamount chain are mostly extinct volcanoes that formed above the Bowie hotspot. This is a 100-to-150-km-wide morphological swell presumably of thickened hotspot generated crust, although there are no seismic refraction data across the swell to define crustal thickness. The crest of one such peak, Patton Seamount originally formed off Washington state as a submerged volcano 33 million years ago. Over time, as the Pacific Plate moved steadily northwest, Patton Seamount was carried off the Bowie hotspot and into the Gulf of Alaska. New volcanoes were formed one after another over the hotspot, creating the Kodiak–Bowie Seamount chain.

Explorations of the Kodiak–Bowie Seamount chain have shown that despite the fact that most of the seamounts were created by the Bowie hotspot, all are unique in their size, shape, and volcanic features. The seamounts teem with deep-sea corals, sponges, and fish. Recent expeditions to these seamounts using manned submersibles and ROVs have discovered many marine species and have greatly expanded the knowledge of the range of deep sea corals in this region. For example, the Bowie Seamount is a biologically rich area with a dynamic and productive ecosystem. Because of this unique biological rich area, Bowie Seamount was declared a Pilot Marine Protected Area on December 8, 1998.The Kodiak–Bowie seamount chain is at the northern triple junction between the Pacific, North American, and Juan de Fuca plates. Available age determinations on Kodiak and Giacomini Seamounts give an approximate average rate of movement along the chain of 6.5 cm (3 in) per year.

List of submarine volcanoes

A list of active and extinct submarine volcanoes and seamounts located under the world's oceans. There are estimated to be 40,000 to 55,000 seamounts in the global oceans. Almost all are not well-mapped and many may not have been identified at all. Most are unnamed and unexplored. This list is therefore confined to seamounts that are notable enough to have been named and/or explored.

List of volcanoes in the Pacific Ocean

A list of active and extinct volcanoes in the Pacific Ocean.

Peirce Seamount

Peirce Seamount, also called Pierce Seamount, is a seamount located in the Pacific Ocean west of the Queen Charlotte Islands, British Columbia, Canada. It lies between Denson Seamount and Hodgkins Seamount and is member of the Kodiak-Bowie Seamount chain, a chain of seamounts in southeastern Gulf of Alaska stretching from the Aleutian Trench in the north to Bowie Seamount in the south.

Protected areas of Canada

Protected areas of Canada have been created to protect ecological integrity, as well as to provide areas for recreation and education. Most of the protected areas in Canada are terrestrial; however, there has been a growing focus to also protect coastal areas, such as the Bowie Seamount. Different classifications of protected area exist, depending on the organization which manages them. Similarly, some protected areas have a greater focus on ecological integrity than others.


A seamount is a mountain rising from the ocean floor that does not reach to the water's surface (sea level), and thus is not an island, islet or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from the seafloor to 1,000–4,000 m (3,300–13,100 ft) in height. They are defined by oceanographers as independent features that rise to at least 1,000 m (3,281 ft) above the seafloor, characteristically of conical form. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. During their evolution over geologic time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. After they have subsided and sunk below the sea surface such flat-top seamounts are called "guyots" or "tablemounts".There are more than 14,500 seamounts, of which 9,951 seamounts and 283 guyots, covering a total of 8,796,150 km2 (3,396,210 sq mi) have been mapped but only a few have been studied in detail by scientists. Seamounts and guyots are most abundant in the North Pacific Ocean, and follow a distinctive evolutionary pattern of eruption, build-up, subsidence and erosion. In recent years, several active seamounts have been observed, for example Loihi in the Hawaiian Islands.

Because of their abundance, seamounts are one of the most common marine ecosystems in the world. Interactions between seamounts and underwater currents, as well as their elevated position in the water, attract plankton, corals, fish, and marine mammals alike. Their aggregational effect has been noted by the commercial fishing industry, and many seamounts support extensive fisheries. There are ongoing concerns on the negative impact of fishing on seamount ecosystems, and well-documented cases of stock decline, for example with the orange roughy (Hoplostethus atlanticus). 95% of ecological damage is done by bottom trawling, which scrapes whole ecosystems off seamounts.

Because of their large numbers, many seamounts remain to be properly studied, and even mapped. Bathymetry and satellite altimetry are two technologies working to close the gap. There have been instances where naval vessels have collided with uncharted seamounts; for example, Muirfield Seamount is named after the ship that struck it in 1973. However, the greatest danger from seamounts are flank collapses; as they get older, extrusions seeping in the seamounts put pressure on their sides, causing landslides that have the potential to generate massive tsunamis.

Submarine volcano

Submarine volcanoes are underwater vents or fissures in the Earth's surface from which magma can erupt. Many submarine volcanoes are located near areas of tectonic plate formation, known as mid-ocean ridges. The volcanoes at mid-ocean ridges alone are estimated to account for 75% of the magma output on Earth. Although most submarine volcanoes are located in the depths of seas and oceans, some also exist in shallow water, and these can discharge material into the atmosphere during an eruption. The Kolumbo submarine volcano in the Aegean Sea was discovered in 1650 when it erupted, killing 70 people on the nearby island of Santorini. The total number of submarine volcanoes is estimated to be over 1 million (most are now extinct), of which some 75,000 rise more than 1 km above the seabed.Hydrothermal vents, sites of abundant biological activity, are commonly found near submarine volcanoes.

Tuzo Wilson Seamounts

The Tuzo Wilson Seamounts, also called J. Tuzo Wilson Knolls and Tuzo Wilson Knolls, are two young active submarine volcanoes off the coast of British Columbia, Canada, located 200 km (124 mi) northwest of Vancouver Island and south of the Haida Gwaii archipelago (briefly known as the Queen Charlotte Islands.) The two seamounts are members of the Kodiak-Bowie Seamount chain, rising 500 m (1,640 ft) to 700 m (2,297 ft) above the mean level of the northeastern Pacific Ocean and is a seismically active site southwest of the southern end of the Queen Charlotte Fault. They are named after Canadian geologist John Tuzo Wilson.


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