Background Info

In 2002 and 2003, the National Oceanic and Atmospheric Administration (NOAA) conducted a major research study of the Puerto Rico Trench. Situated just north of the Commonwealth of Puerto Rico, the Puerto Rico Trench separates the Atlantic Ocean and the Caribbean Sea.

The ocean trench is a geologically complex site. The Caribbean and North American tectonic plates are scraping by each other, making a huge transform fault that extends from the Puerto Rico Trench to the coast of Central America. The Caribbean plate is shifting east, while the North American plate is shifting west.

In addition to the transform fault, the Puerto Rico Trench is also associated with a subduction zone. To the trench's east, the heavy North American plate, which carries the northern Atlantic Ocean as well as the continent of North America, is being subducted beneath the smaller Caribbean plate.

Fast Facts

According to NOAA:

  • The deepest part of the Puerto Rico Trench is just over 8,600 meters (5.3 miles).
  • A large fault system, the Bunce Fault, was discovered in very deep water near the trench. The Bunce Fault is similar to the San Andreas Fault in California. The Bunce Fault was named after Dr. Elizabeth (Betty) Bunce, a marine geophysicist who investigated the Puerto Rico Trench in the 1950s.
  • The southern side of the trench, north of Puerto Rico, is covered with a smooth layer of limestone.
  • A mud volcano was discovered at a depth of 7,900 meters (25,919 feet). The volcano spewed mud as far as 10 kilometers (6.2 miles).
  • The Puerto Rico Trench is a very flat depression, 280 kilometers (175 miles) long.

For Further Exploration


Term Part of Speech Definition Encyclopedic Entry



edge of land along the sea or other large body of water.

Encyclopedic Entry: coast



self-governing territory affiliated with the United States, used for Puerto Rico and the Northern Mariana Islands.



one of the seven main land masses on Earth.

Encyclopedic Entry: continent



having to do with the physical formations of the Earth.

National Oceanic and Atmospheric Administration (NOAA)


U.S. Department of Commerce agency whose mission is to "understand and predict changes in climate, weather, oceans, and coasts; to share that knowledge and information with others, and; to conserve and manage coastal and marine ecosystems and resources."

ocean trench


a long, deep depression in the ocean floor.

Encyclopedic Entry: ocean trench

Puerto Rico Trench


deepest place in the Atlantic Ocean, 8,400 meters (27,560 feet) deep.



scientific observations and investigation into a subject, usually following the scientific method: observation, hypothesis, prediction, experimentation, analysis, and conclusion.



to place or arrange.



to pull downward or beneath something.

subduction zone


area where one tectonic plate slides under another.

tectonic plate


large, moveable segment of the Earth's crust.

transform fault


boundary between two tectonic plates, where the plates are moving horizontally or vertically in opposite directions, not against or away from each other. Also called a conservative plate boundary.


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United States Geological Survey


Caryl-Sue, National Geographic Society

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