A 5.0 magnitude earthquake hit southern Puerto Rico on Saturday at a shallow depth, raising concerns about unstable infrastructure in a region that has been hit by quakes every day for nearly a month. At least one small landslide was reported.

The U.S. Geological Survey said the quake occurred at a depth of eight miles around the southern coastal town of Guayanilla, located close to the epicenters of most of the recent earthquakes.

"We felt it really hard," town spokesman Danny Hernandez told The Associated Press, saying authorities were patrolling the area to investigate any potential damage.

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The newest quake comes a day after hundreds of people in the island's southern region were evacuated from earthquake shelters that flooded after heavy rains hit the U.S. territory. In the coastal city of Ponce alone, more than 350 people on Friday were moved back into a school that served as the initial shelter when the ground first began shaking, Angel Vazquez, the city's emergency management director, told the AP.

He said no damage was immediately reported in Ponce, but that crews were out inspecting buildings in areas affected by a 6.4 magnitude quake that hit January 7, killing one person and damaging hundreds of homes. A 5.9 aftershock that hit the same area on January 11 caused further damage.

The ground in southern Puerto Rico first began shaking on December 28, and while experts say several local faults are to blame, they are still analyzing data to determine why the earthquakes continue.

U.S. President Donald Trump has approved a major disaster declaration for more than a dozen municipalities in Puerto Rico following earthquakes that officials say have caused more than $200 million in damage. More than 4,000 people remain in shelters, and officials expected that number to rise as a result of Saturday's quake.