The Septentrional-Orient fault zone (SOFZ) is a system of coaxial left lateral-moving strike slip faults which runs along the northern side of the island of Hispaniola

Hispaniola

Hispaniola is a major island in the Caribbean, containing the two sovereign states of the Dominican Republic and Haiti. The island is located between the islands of Cuba to the west and Puerto Rico to the east, within the hurricane belt...

 where the Dominican Republic

Dominican Republic

The Dominican Republic is a nation on the island of La Hispaniola, part of the Greater Antilles archipelago in the Caribbean region. The western third of the island is occupied by the nation of Haiti, making Hispaniola one of two Caribbean islands that are shared by two countries...

 and Haiti

Haiti

Haiti , officially the Republic of Haiti , is a Caribbean country. It occupies the western, smaller portion of the island of Hispaniola, in the Greater Antillean archipelago, which it shares with the Dominican Republic. Ayiti was the indigenous Taíno or Amerindian name for the island...

 are located. The SOFZ shares approximately half of the relative motion between the North American

North American Plate

The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, Bahamas, and parts of Siberia, Japan and Iceland. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust...

 and Caribbean

Caribbean Plate

The Caribbean Plate is a mostly oceanic tectonic plate underlying Central America and the Caribbean Sea off the north coast of South America....

 tectonic plates with the Enriquillo-Plantain Garden fault zone

Enriquillo-Plantain Garden fault zone

The Enriquillo–Plantain Garden fault zone is a system of coaxial left lateral-moving strike slip faults which runs along the southern side of the island of Hispaniola, where the Dominican Republic and Haiti are located...

 which runs along the southern side of Hispaniola. Both faults merge into the Cayman Trench to the west. Some researchers believe that the Enriquillo-Plantain Garden fault zone and the SOFZ bound a microplate, dubbed the Gonâve Microplate

Gonâve Microplate

The Gonâve Microplate forms part of the boundary between the North American Plate and the Caribbean Plate. It is bounded to the west by the Cayman spreading center, to the north by the Septentrional-Oriente fault zone and to the south by the Walton fault zone and the Enriquillo-Plantain Garden...

, a 190000 km² (73,359.4 sq mi) area of the northern Caribbean Plate that is in the process of shearing off the Caribbean Plate and accreting to the North America Plate.

A major tremor on this fault destroyed the city of Cap-Haïtien

Cap-Haïtien

Cap-Haïtien is a city of about 190,000 people on the north coast of Haiti and capital of the Department of Nord...

and other cities in the northern part of Haiti and the Dominican Republic on 7 May 1842.