Puerto Rico has been hit by a 6.4-magnitude earthquake, resulting in at least one death and causing island-wide power cuts, officials say.
This most recent quake, which began early on Tuesday morning, was the strongest in a series of quakes that have damaged Puerto Rico this week.
Authorities said the island's power plants suffered some damage and power was shut off as a protective measure.
The US National Tsunami Warning Center said there was no tsunami threat.
The initial earthquake struck at 4.24am local time, just south of the Caribbean island at a depth of 10km, according to the US Geological Survey (USGS). It was followed hours later by a magnitude 6 aftershock.
Strong shaking was reported, causing damage to buildings and homes.
A 73-year-old man in the southern city of Ponce was confirmed dead.
Mayor Mayita Melendez said the man died when a wall fell on him in his home, Puerto Rican newspaper El Nuevo Dia reported.
Eight others were injured, Melendez told WAPA television.
On Monday, Puerto Rico was hit by a 5.8-magnitude quake that destroyed a popular tourist rock formation, damaged homes and caused power cuts.
Homes, buildings and roads have been damaged and the island has been without power since the second earthquake, local media reported.
Automatic protection systems caused all power plants to shut down, but the Puerto Rico Electric Power Authority expected most power to return later on Tuesday.
Officials said two planes were checking infrastructure across the island.
Puerto Rico Governor Wanda Vasquez closed non-essential public offices for the day and a number of schools cancelled classes.
The USGS reported the quakes were part of an ongoing series that began on 28 December and caused hundreds of small quakes in the region.
Puerto Rico, a US territory of about 3.2 million people, is situated between the North America and Caribbean tectonic plates, making it vulnerable to earthquakes.
The island is still recovering from Hurricane Maria, a Category 5 storm that devastated parts of the Caribbean in September 2017. In Puerto Rico alone, the hurricane is estimated to have killed 2,975 people and caused $100bn (local currency) of damage.