A powerful magnitude 7.7 earthquake struck south of Cuba and northwest of Jamaica on Tuesday, but there were no reports of casualties or heavy damage.

It was centred 139 kilometres northwest of Montego Bay, Jamaica, and 140 kilometres west-southwest of Niquero, Cuba, according to the U.S. Geological Survey (USGS). It hit at 2:10 p.m. ET, and the epicentre was a relatively shallow 10 kilometres beneath the surface.

The International Tsunami Information Center initially warned that "hazardous tsunami waves" were possible within 300 kilometres of the epicentre.

The agency later said that the tsunami threat had passed.

The Cayman Islands were rocked by several of the strong aftershocks that followed in the area, including one measured at magnitude 6.1. Water was cut off to much of Grand Cayman Island, and public schools were cancelled for Wednesday.

Dr. Enrique Arango Arias, head of Cuba's National Seismological Service, told state media that there had been no serious damage or injuries reported.

Gov. Carlos Joaquin Gonzalez of Mexico's Quintana Roo, which is home to Cancun, Tulum and other popular beach resorts, said the earthquake was felt in multiple parts of the low-lying Caribbean state but there were no immediate reports of damage or injuries. Mexico's National Seismological Service reported that the quake was felt in five states including as far away as Veracruz, on the country's Gulf Coast.

The quake could be felt strongly in Santiago, the largest far-eastern Cuban city, said Belkis Guerrero, who works in a Catholic cultural centre in the centre of Santiago.

"We were all sitting, and we felt the chairs move," she said. "We heard the noise of everything moving around."

She said there was no apparent damage in the heart of the colonial city.

"It felt very strong, but it doesn't look like anything happened," she told The Associated Press.

'Like a big dump truck'

The quake was also felt a little farther east at the U.S. navy base at Guantanamo Bay on the southeastern coast of Cuba. There were no immediate reports of injuries or damage, said J. Overton, a spokesperson for the installation, which has a total population of about 6,000.

Several South Florida buildings were being evacuated as a precaution, according to city of Miami and Miami-Dade County officials. No injuries or road closures were reported. No shaking was felt at the Hard Rock stadium in Miami Gardens, which will host the Super Bowl on Sunday.

In the Cayman Islands, the quake left cracked roads and what appeared to be sewage spilling from cracked mains. There were no immediate reports of deaths, injuries or more severe damage, said Kevin Morales, editor-in-chief of the Cayman Compass newspaper.

The islands see so few earthquakes that newsroom staff were puzzled when it hit, he said.

"It was just like a big dump truck was rolling past," Morales said. "Then it continued and got more intense."

People running 'en masse'

CBC Saskatchewan's Fiona Odlum, who is on vacation on Grand Cayman, said she was sitting in a parked truck when it started rocking back and forth. People began running "en masse," she told CBC News Network, and she saw water coming up from manhole covers.

"Even after the rocking and shaking stopped, you still felt it," she said.

About four cruise ships are in Grand Cayman's port, she said, and thousands of passengers were lined up on the pier to get back on board.

Dr. Stenette Davis, a psychiatrist at a Cayman Islands hospital, also said she saw manhole covers blown off by the force of the quake, and sewage exploding into the street, but no more serious damage.

Claude Diedrick, 71, who owns a fencing business in Montego Bay, said he was sitting in his vehicle reading when the earth began to shake.

"It felt to me like I was on a bridge and like there were two or three heavy trucks and the bridge was rocking, but there were no trucks," he said.

He said he had seen no damage around his home in northern Jamaica.

The USGS initially reported the magnitude at 7.3.