HONG KONG — A powerful earthquake struck southeastern Taiwan on Sunday afternoon, toppling at least one building and causing shaking that was felt across the island.

The quake was centered in Taitung County and registered a preliminary magnitude of 6.8, Taiwan’s Central Weather Bureau said. Its epicenter was shallow at about six miles below the earth’s surface, the United States Geological Survey reported.

The Japan Meteorological Agency issued a tsunami advisory for some of the country’s southern islands lying east of Taiwan.

Early reports of damage included a 7-Eleven convenience store that collapsed in the town of Yuli. Rescue crews were trying to save four people trapped in the building, Taiwan’s state-run Central News Agency said.

Taiwan sits near the boundaries of several tectonic plates, and their collisions cause frequent earthquakes. A magnitude-6.4 earthquake that struck on Saturday night was also centered in Taitung County, the Central Weather Bureau said.

Amy Chang Chien and John Liu contributed reporting from Taipei, Taiwan.