SAN JUAN, Puerto Rico – Puerto Rico, on January 11, was rocked by a 5.9-magnitude earthquake, just a few days after the US territory was shaken by its biggest quake in a century.

According to the United States Geological Survey (USGS), the most recent earthquake happened around 9 a.m. local time, about 8 miles south of Indios, Puerto Rico, in the Caribbean Sea, at a depth of 6.2 miles. The USGS first said the preliminary magnitude was 6.0.

Randy Baldwin, a geophysicist at the U.S. Geological Survey, said that the 5.9 magnitude quake is considered an aftershock along with several other 5.0 magnitude aftershocks overnight. “The one this morning is the strongest one” since the big earthquake on Tuesday, he said, referring to the massive 6.4 earthquakes that rocked the island on January 7, killing one resident. The 6.4 earthquakes have been the biggest to hit the island in a century.

The January 7 earthquake caused damage to hundreds of homes, schools and other public buildings on the southern coast of the island. The earthquake also left thousands of residents without power, which was later restored to 95% of the island before the January 11 quake. The Puerto Rico Electric Power Authority said that the most recent aftershock has left about 7% of the island without power.

Hundreds of quakes and aftershocks have shaken the island since the new year, according to U.S. Geological Survey data.