Lōihi Seamount: The Next Hawaiian Island

Lō‘ihi Seamount: The Next Hawaiian Island

[Illustration: Lō‘ihi]

 

If you could speed up time and look at the Hawaiian Islands, you would see them rising up out of the ocean one by one, as each in turn was carried northwest by the Pacific Plate, away from the relatively stationary plume of lava erupting from the seafloor.  You would then see the volcanic islands become dormant and extinct, one after another eroding away back into the sea. 

If you could see into the future, you would see the next Hawaiian Island rising above the sea—that island would be Lō‘ihi, which today is an undersea volcano (called a seamount) about 18 miles (29 km) off the southeast coast of Hawai‘i Island. 

Lō‘ihi Seamount is currently more than 9,000 feet (2,743 m) tall and about 3,116 feet (950 m) below the surface of the Pacific Ocean.  The erupting summit of Lō‘ihi should rise above the water in about 50,000 to 200,000 years from now to become the next Hawaiian Island.

Lō‘ihi is quite active, volcanically and tectonically.  In just one three-week period beginning July 17, 1996, more than 4,000 earthquakes were recorded near Lō‘ihi’s summit, a record for Hawaiian volcanoes.   An ancient Hawaiian proverb states, “Nei ka honua, he ōla‘i ia” (“When the earth trembles, it is an earthquake”), said to mean, “We know what it is by what it does.”[i]

The intense water pressure at Lō‘ihi’s summit causes erupting lava to immediately cool and turn into volcanic glass.  Water temperatures around the summit may reach 140º Fahrenheit (60º Celsius), even though the temperature of the surrounding water is near freezing. 

The University of Hawai‘i research boat called Ka‘imikai O Kanaloa carries a deep-diving manned submersible called Pisces V that has been used to explore Lō‘ihi’s volcanic activity and the life forms that grow near the summit.  Strange undersea colonies of volcanic life thrive near Lō‘ihi’s sulfurous hot water vents, and in the 1,200-foot (366-m) deep pit craters in Lō‘ihi’s summit caldera. 

Superheated sulfur-yellow water was seen shooting out in big plumes in an area of Lō‘ihi’s summit that the scientists named “Pele’s Vents.”  They also recently discovered a new species of shrimp there—it is orange and just a few inches long, and blends in with the orange rocks. 

The summit area later collapsed into what they named Pele’s Pit, a 1,000-foot (305-m) deep crater that is 800 feet (244 m) across and filled with an estimated 300 million tons (272 mtons) of rock.

 

Archaea—Bacteria and Iron Deposits

Another life form growing near Lō‘ihi’s hot vent fields are single-celled archaea, which lack nuclei yet have DNA similar to higher life forms.  Researchers theorize that archaea resembles prehistoric life forms that existed when the planet had a harsher environment (similar to the conditions on Lō‘ihi today).  The archaea, absent any link to sunlight and photosynthesis, feed on the chemical energy of the toxic plumes of super-heated water emitted by Lō‘ihi.

Water emitting from Lō‘ihi’s vents contains about 20,000 times as much carbon dioxide as the surrounding seawater.  This helps bacteria live near the hydrothermal vents and creates massive iron deposits.  Near the hydrothermal vents everything is orange because it is carpeted with 3-foot (.9-m) thick iron deposits created by these unique bacteria that oxidize iron. 

When the Pisces V research boat touched down on Lō‘ihi’s summit, it instantly caused a bacterial snowstorm of iron deposits that puffed up all around the submersible.

 

Chemosynthesis and Deep-Sea Vent Species

All of the life forms near the hydrothermal vents on Lō‘ihi’s summit are very rare, surviving under immense pressure with no connection to sunlight or photosynthesis. 

Instead they exist by a process known as chemosynthesis, which utilizes only heat and chemicals (such as sulfur), to produce a whole variety of rare luminescent creatures.  These include various microbes loaded with heavy metals and toxic compounds.

There are lots of other places in the world where deep-sea vents occur, and many different species live near these hydrothermal vents.  For example, the species living near the hydrothermal vents of the Galapagos Rift include giant clams, 6-foot (1.8-m) long tubeworms, and other strange chemosynthetic creatures.  The species around Lō‘ihi’s vents tend to be smaller and different than those near other deep-sea vents. 

The unique biological communities thriving on Lō‘ihi’s summit are providing scientists with fascinating new insights into deep-sea life and chemical processes. 

They have also concluded that lava from magmatic hot spot volcanoes (like all Hawaiian Island volcanoes, which are also called shield volcanoes) are very different from the lava that erupts from the stratovolcanoes around the edges of the Pacific Ocean where the Pacific Plate dives (subducts) beneath other tectonic plates, forming the “Ring of Fire.”

Researchers theorize that the lava of Lō‘ihi is coming from extremely deep in the Earth (near the very core), and that its chemical composition holds clues to Earth’s origins.  This chemical composition is analyzed by comparing helium isotope ratios, and by using other advanced analytical techniques.

[Photograph: Hydrothermal vent]



[i]p. 251, Pukui, Mary Kawena.  ‘Ōlelo No‘eau: Hawaiian Proverbs & Poetical Sayings.  Honolulu: Bishop Museum Press, 1983.  Proverb 2307.