JAKARTA, Indonesia — A powerful earthquake struck Wednesday evening in the Indian Ocean southwest of the Indonesian island of Sumatra, prompting officials there and other nearby countries to post warnings of a possible tsunami. But the warnings were soon dropped when no signs of a tsunami were detected.
Indonesian officials said the earthquake had apparently caused some deaths, but did not yet have specifics about the number of casualties or about any damage. “There are some who have died,” said Heronimus Guru, the deputy head of operations with the National Search and Rescue Agency, according to The Associated Press.
President Joko Widodo of Indonesia was in Sumatra at the time of the earthquake and was safe, staying overnight at a hotel in Medan in the northern part of the island, the news agency said, citing officials on his staff. The quake was not felt in Medan, according to a resident interviewed by the news agency, but Indonesian officials told local television stations that it was felt in several other cities in Sumatra, and Twitter users reported feeling it as far away as Singapore.
The U.S. Geological Survey gave a preliminary magnitude of 7.8 for the earthquake, and said it had been centered about 500 miles offshore and about six miles below the surface. That is fairly shallow for a large quake, and shallow quakes tend to do the most damage, but the long distance from shore may have mitigated its effects.
Tsunamis can radiate swiftly from the quakes that cause them, and officials in Indonesia, Australia and Thailand all issued warnings shortly after the earthquake urging coastal residents to take precautions. But those warnings were later canceled.
Andi Eka Sakya, director general of the Indonesian Meteorology, Climatology and Geophysics Agency, which runs the country’s tsunami early warning center, said that no tsunami had occurred as of 9:15 p.m. Jakarta time, about 90 minutes after the quake struck.
“We are going to remain vigilant for a while, just in case,” he said. “But as of now, there has not been a tsunami, and there was no damage from the earthquake.”
In 2004, a tsunami caused by a very powerful undersea earthquake killed 230,000 people in a dozen countries around the Indian Ocean, most of them in Aceh province on Sumatra. That quake had a magnitude of 9.1, nearly 90 times the strength of the quake on Wednesday.