(CNN) -- U.S. officials were urging residents to evacuate coastal regions in the Indian Ocean after a earthquake with a preliminary magnitude of 8.2 struck off the coast of Indonesia Monday.
The National Oceanic and Atmospheric Administration urged residents within 1,000 kilometers of the epicenter to evacuate coastal regions.
The quake was centered on the same fault line where a December 26 earthquake launched a tsunami that killed at least 175,000 people.
The director of the Pacific Tsunami Warning Center said scientists there feared another tsunami might hit the area.
Charles McCreary said he could not be certain that the quake, which was 203 kilometers (126 miles) from Sibolga on Sumatra Island, would cause a tsunami.
Experts agreed the quake was massive.
"This earthquake has the potential to generate a widely destructive tsunami in the ocean or seas near the earthquake," NOAA said in a statement on its Web site. "Authorities in those regions should be aware of this possibility and take immediate action."