A 6.4-magnitude earthquake struck Puerto Rico before dawn on Tuesday, killing one man, injuring at least eight other people and collapsing buildings in the southern part of the island.
The quake was followed by a series of strong aftershocks, part of a 10-day series of tremors spawned by the grinding of tectonic plates along three faults beneath southern Puerto Rico.
Seismologists say it is impossible to predict when the quakes will stop or whether they will get stronger.
The 6.4-magnitude quake cut power to the island. Authorities said two plants suffered light damage and they expected power to be restored later. Puerto Rico’s main airport was operating normally, using generator power.
Puerto Rico’s governor, Wanda Vasquez, declared a state of emergency and activated the territory’s National Guard. She said 300,000 households remained without running water by late on Tuesday afternoon, and several hundred people were in shelters in affected municipalities.
Teacher Rey Gonzalez told the Associated Press that his uncle was killed when a wall collapsed on him at the home they shared in Ponce. He said 73-year-old Nelson Martinez was disabled and that he and his father cared for him.
Eight people were injured in Ponce, mayor Mayita Melendez told WAPA television. Hundreds of people sat in the streets of the city, some cooking food on barbecue grills, afraid to return home for fear of structural damage and aftershocks.
The US Geological Survey said the quake hit at 4.24am just south of the island at a shallow depth of six miles. It initially gave the magnitude as 6.6 but later adjusted it.
At 7.18am, a magnitude-6.0 aftershock hit the same area. People reported strong shaking and staff at a local radio station said live on air that they were leaving their building
A tsunami alert was issued for Puerto Rico and the US Virgin Islands after the initial quake, but was later cancelled.
US President Donald Trump has been briefed on the earthquakes, said Judd Deere, White House deputy press secretary.
“Administration officials, including Fema (Federal Emergency Management Agency) administrator Pete Gaynor, have been in touch with the governor and her team today, and we will continue to monitor the effects and co-ordinate with Puerto Rico officials,” Mr Deere said.
In the historic district of Ponce, authorities evacuated more than 150 people from two buildings they said were in danger of collapsing. Among them were more than two dozen elderly patients from a nursing home who sat in their wheelchairs in silence as the earth continued to tremble.
Much of the damage was reported in the southwest coastal town of Guayanilla, where a 19th-century church partially collapsed.
A 5.8-magnitude quake that struck early on Monday morning collapsed five homes in Guanica and heavily damaged dozens of others. It also caused small landslides and power outages. The quake was followed by a string of smaller tremors.
The shake collapsed a coastal rock formation that had formed a sort of rounded window, Punta Ventana, that was a popular tourist draw in Guayanilla.
Residents in the south of the island have been terrified to go into their homes for fear that another quake will bring buildings down.
The flurry of quakes in Puerto Rico’s southern region began on the night of December 28.
Seismologists say that shallow quakes were occurring along three faults in Puerto Rico’s south-western region – Lajas Valley, Montalva Point and the Guayanilla Canyon – as the North American plate and the Caribbean plate squeeze Puerto Rico.
One of the largest and most damaging earthquakes to hit Puerto Rico occurred in October 1918, when a magnitude 7.3 quake struck near the island’s north-western coast, unleashing a tsunami and killing 116 people.