According to the US Geological Survey (USGS), at least three aftershocks have followed the quake including a magnitude 4.7.
International news reports say Puerto Rico’s Governor Wanda Vázquez Garced said in a tweet that there was no damage.
“The last strong quake to shake the island in recent years occurred in January 2014, when a magnitude-6.4 tremor struck after midnight just north of the island’s north coast at a depth of 17 miles (28 kilometers).
“The most damaging earthquake to hit Puerto Rico in recent history occurred in October 1918, when a magnitude-7.3 quake struck near the island’s northwest coast, causing a tsunami and killing 116 people.
“At the moment, there are no reports of damage or injuries,” the report added.
“The Office of Emergency Management’s offices were already open around the clock ahead of Tropical Depression Karen.
“The official said the quake and aftershocks will not impact the agency ahead of Karen.”
Schools were already closed “in preparation for Karen, which is expected to lash Puerto Rico with gusty winds and rain of as much as 4 to 8 inches”.
“The island was spared just last week by Hurricane Humberto as it skirted north of the island.
“The National Guard also had been activated for the storm, and schools and government offices remained closed as heavy rains were forecast for Puerto Rico on Tuesday, with warnings of possible flooding and landslides.”
Crews were inspecting buildings to ensure their safety.