The East Pacific Rise (EPR) is a mid-ocean rise (usually termed an oceanic rise and not a

mid-ocean ridge A mid-ocean ridge (MOR) is a undersea mountain range, seafloor mountain system formed by plate tectonics. It typically has a depth of about and rises about above the deepest portion of an ocean basin. This feature is where seafloor spreading ...

due to its higher rate of spreading that results in less elevation increase and more regular terrain), at a divergent tectonic plate boundary, located along the floor of the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

. It separates the Pacific plate to the west from (north to south) the North American plate, the Rivera plate, the Cocos plate, the

Nazca plate The Nazca plate or Nasca plate, named after the Nazca region of southern Peru, is an oceanic list of tectonic plates, tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction, along the Peru– ...

, and the Antarctic plate. It runs south from the

Gulf of California The Gulf of California (), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Vermejo''), is a marginal sea of the Pacific Ocean that separates the Baja California peninsula from ...

in the

Salton Sea The Salton Sea is a shallow, landlocked, highly salinity, saline endorheic lake in Riverside County, California, Riverside and Imperial County, California, Imperial counties in Southern California. It lies on the San Andreas Fault within the S ...

basin in

Southern California Southern California (commonly shortened to SoCal) is a geographic and Cultural area, cultural List of regions of California, region that generally comprises the southern portion of the U.S. state of California. Its densely populated coastal reg ...

to a point near , where it joins the Pacific-Antarctic Ridge (PAR) trending west-south-west towards

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

, near

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

(though in some uses the PAR is regarded as the southern section of the EPR). Much of the rise lies about off the South American coast and reaches a height about above the surrounding seafloor.

Overview

The

oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramaf ...

is moving away from the East Pacific Rise to either side. Near

Easter Island Easter Island (, ; , ) is an island and special territory of Chile in the southeastern Pacific Ocean, at the southeasternmost point of the Polynesian Triangle in Oceania. The island is renowned for its nearly 1,000 extant monumental statues, ...

the rate is over per year which is the fastest in the world. However, on the northern end, it is much slower at only roughly per year. On the eastern side of the rise, the eastward-moving Cocos and Nazca plates meet the westward moving

South American plate The South American plate is a major tectonic plate which includes the continent of South America as well as a sizable region of the Atlantic Ocean seabed extending eastward to the African plate, with which it forms the southern part of the Mid ...

and the North American plate and are being subducted under them. The belt of

volcano A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most oft ...

s along the

Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

and the arc of volcanoes through

Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...

and

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

are the direct results of this collision. Due east of the Baja California peninsula, the Rise is sometimes referred to as the Gulf of California Rift Zone. In this area, newly formed oceanic crust is intermingled with rifted continental crust originating from the North American plate. Near

, the East Pacific Rise meets the Chile Rise at the Easter Island and Juan Fernandez microplates, trending off to the east where it subducts under the

at the Peru–Chile Trench along the coast of southern

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

. This portion of the Rise has been referred to as the Cape Adare-Easter Island Ridge, Albatross Cordillera, Easter Island Cordillera, Easter Island Rise, and Easter Island Swell. Parts of the East Pacific Rise have oblique spreading, such as the Nazca–Pacific plate boundary between 29°S and 32°S. This is

seafloor spreading Seafloor spreading, or seafloor spread, is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. History of study Earlier theories by Alfred Wegener ...

that is not orthogonal to the nearest ridge segment. The southern extension of the East Pacific Rise (the PAR) merges with the Southeast Indian Ridge at the Macquarie triple junction south of

. The southern stretch of the East Pacific Rise is also one of the fastest-spreading divergent boundaries on Earth, peaking at /year. Along the East Pacific Rise the

hydrothermal vent Hydrothermal vents are fissures on the seabed from which geothermally heated water discharges. They are commonly found near volcanically active places, areas where tectonic plates are moving apart at mid-ocean ridges, ocean basins, and hot ...

s called

black smoker Hydrothermal vents are fissures on the seabed from which geothermally heated water discharges. They are commonly found near volcanically active places, areas where tectonic plates are moving apart at mid-ocean ridges, ocean basins, and hots ...

s were first discovered by the RISE project in 1979, and have since been extensively studied. These vents are forming volcanogenic massive sulfide ore deposits on the ocean floor. Many unique deep-water creatures have been found with vents, that subsist in a chemosynthetic ecosystem rather than one using

photosynthesis Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...

References

External links

East Pacific Rise 2004
– Scripps Institution of Oceanography
Columbia University Researchers Find Key to the Formation of New Seafloor Spreading Centers
–

Columbia University Columbia University in the City of New York, commonly referred to as Columbia University, is a Private university, private Ivy League research university in New York City. Established in 1754 as King's College on the grounds of Trinity Churc ...

{{Authority control Plate tectonics Underwater ridges of the Pacific Ocean Geology of California Salton Trough

Overview

See also

References

External links