A magnitude-7.6 earthquake shook the Caribbean Sea southwest of the Cayman Islands on Saturday, according to the U.S. Geological Survey (USGS), and some islands and countries urged people near the coastline to move inland in case of a tsunami.

The quake struck at 6:23 p.m. local time in the middle of the sea and had a depth of 10 kilometres, the USGS said. Its epicentre was located 209 kilometres south-southwest of George Town in the Cayman Islands.

The U.S. National Tsunami Warning Center said there is no tsunami alert for the U.S. mainland, but it issued a tsunami advisory for Puerto Rico and the U.S. Virgin Islands that was later cancelled.

The sounding of alarms in Puerto Rico's northwest region caused people to leave coastal areas, creating heavy traffic, according to local media.

Hazard Management Cayman Islands urged residents near the coast to move inland and to higher ground. It said wave heights of 0.3 to one metre are expected.

Puerto Rico Gov. Jenniffer González-Colón said in a statement that she is in contact with emergency agencies after the tsunami advisory, but she did not recommend anyone leave the coast.

The Dominican government also issued a tsunami alert and recommended residents on the coast move to high areas "of more than 20 metres of altitude and two kilometres inland." But it later cancelled the alert.

The Cuban government asked people to leave beachfront areas. The Bahamas Department of Meteorology also issued a tsunami advisory but urged its residents only to be "vigilant."

Honduran authorities said there are no immediate reports of damage, but it urged residents to stay away from beaches.

Later, the U.S. government's National Oceanic and Atmospheric Administration said "tsunami waves reaching one to three metres above the tide level are possible along some coasts of Cuba."

"Actual amplitudes at the coast may vary from forecast amplitudes due to uncertainties in the forecast and local features," the agency said in a report.