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The 'Puerto Rico Trench' is an oceanic trench located on the boundary between the Caribbean Sea and the Atlantic Ocean. The trench is associated with a complex transition between the subduction zone to the south along the Lesser Antilles island arc and the major transform fault zone or plate boundary that extends west between Cuba and Hispaniola through the Cayman Trench to the coast of Central America. Scientific studies have concluded that an earthquake occurring along this fault zone could generate a significant tsunami.
The island of Puerto Rico lies immediately to the south of the fault zone and the trench. The trench is 800 kilometers (500 mi) long and has a maximum a depth of 8,605 meters (28,232 ft) at Milwaukee Deep, which is the deepest point in the Atlantic Ocean.

Contents

Geology

Public awareness

Earthquake history

See also

References

Geology

The Puerto Rico Trench is located at a boundary between two plates that pass each other along a transform boundary with only a small component of subduction. The Caribbean Plate is moving to the east while the North American Plate is moving to the west. The North American Plate is subducting the Caribbean Plate to the southeast of the trench. This subduction zone explains the presence of active volcanoes over the southeastern part of the Caribbean Sea. Volcanic activity is frequent along the island arc southeast from Puerto Rico to the coast of South America.
Puerto Rico, the United States Virgin Islands, British Virgin Islands and the Dominican Republic do not have active volcanoes; however they are at risk from earthquakes and tsunamis.

Public awareness

Knowledge of the earthquake and tsunami risks has not been widespread among the general public of the islands located near the trench. Governments have generally spoken little about the risks for two main reasons. First: tourism is essential for those nations to survive; wider knowledge of the danger may cut revenue generated by the industry. Second: the governments want to prevent fear among the local population.
Since 1988, the Puerto Rican Seismic Society has been trying to use the Puerto Rican media to inform people about a future earthquake that could result in a catastrophic tragedy.
Following the 2004 tsunami that affected more than forty countries in the Indian ocean, many more people now fear of the consequences that such an event would bring to the Caribbean. Local governments have begun emergency planning. In the case of Puerto Rico and the U.S. Virgin Islands, the United States government has been studying the problem for years [1] and is increasing its seismic investigations and developing tsunami warning systems.

Earthquake history

On 11 October 1918, the western coast of the island was hit by a major earthquake, which is famous in the area, and caused a tsunami. In 1953, Santo Domingo, Dominican Republic was affected by the Santo Domingo earthquake. Experts blame both tragic earthquakes on the Puerto Rico trench fault.
Puerto Rico in particular has always been an area of concern to earthquake experts because, apart from the 1918 episode, there are frequent cases of tremors in and around the island. A 1981 tremor was felt across the island, while another in 1985 was felt in the towns of Cayey and Salinas.

Earthquake location	Date	Magnitude
Dominican Republic	1953	6.9
Mona Canyon	1946	7.5
Dominican Republic	1946	8.1
Mona Canyon	1918	7.5
Anegada Trough	1867	7.5
Puerto Rico Trench	1787	8.1

[2]

See also

★ Plate tectonics

★ Caribbean Plate

★ Oceanic trench

References

★ NOAA Ocean Explorer

★ Sound Waves 03 USGS

★ Sound Waves 04

★ Woods Hole USGS

★ Puerto Rico Seismic Network web site