A 6.8 magnitude earthquake hit the sparsely populated southeastern part of Taiwan on Sunday, the island"s weather bureau said, derailing train carriages, causing a convenience store to collapse and trapping people on a mountain, Reuters reported. The weather bureau said the epicenter was in Taitung county, and followed a 6.4 magnitude temblor on Saturday evening in the same area, which caused no casualties. The US Geological Survey measured Sunday"s quake at a magnitude 7.2 and at a depth of 10 km (six miles). Taiwan"s fire department said two people were trapped in a building housing a convenience store that collapsed in Yuli and two people had been rescued, while three people whose vehicle fell off a damaged bridge were rescued and taken to hospital. The Taiwan Railways Administration said three carriages came off the rails at Dongli station in eastern Taiwan after part of the platform canopy collapsed. The fire department said one person was injured. Around 68 people are also trapped on the scenic Chike mountain area by a blocked road, though there are no injuries, the department added. About 20 passengers were evacuated after a train derailed in the area, but there were no casualties from the incident, the Taiwan Railway Administration said. Kolas Yotaka, a former presidential spokeswoman who is running for local elections in Hualien county, said that damages were also reported at a local school. Taiwan"s President Tsai Ing-wen activated the island"s Central Emergency Operation Center following the quake. Taiwanese residents have been asked to stay alert to avoid potential aftershocks, Tsai said in a recorded statement. About 110 soldiers have also been deployed in Hualien county, along the island"s eastern coast, to assist with disaster relief efforts, Taiwan"s Defense Ministry spokesman Sun Li-fang said. The US Pacific Tsunami Warning Center issued a warning for Taiwan after the tremor but later lifted the alert. Japan"s weather agency lifted a tsunami warning for part of Okinawa prefecture. The quake could be felt across Taiwan, the weather bureau said. Buildings shook briefly in the capital Taipei. Science parks in the southern cities of Tainan and Kaohsiung, home to major semiconductor factories, said there was no impact on operations. Taiwan Semiconductor Manufacturing Co (TSMC), the world"s largest contract chipmaker, said there was "no known significant impact for now". Taiwan lies near the junction of two tectonic plates and is prone to earthquakes. The USGS reported that a 6.9-magnitude earthquake occurred on Sunday off the southeast coast of Taiwan. A tsunami warning has been issued by Japan as a result of the strong earthquake. The USGS lowered the earthquake from its initial strength of 7.2 to 6.9 magnitude. There have been numerous tremors since the same area was struck by an earthquake on Saturday with a magnitude of 6.6. But Sunday"s quake was much stronger. Japan"s Meteorological Agency issued a tsunami advisory to remote islands near Taiwan. Waves as high as one meter were expected to arrive around 4 p.m. (0700 GMT), it added. Live TV footage from the affected islands did not immediately show clear signs of high waves. The China Earthquake Network Centre said tremors were clearly felt in coastal areas including Fujian, Guangdong, Jiangsu and Shanghai. Taiwan is regularly hit by earthquakes as the island lies near the junction of two tectonic plates. The island sits on the Pacific "Ring of Fire", an arc of intense seismic activity that stretches through Southeast Asia and across the Pacific basin. Taiwan"s deadliest ever quake was a 7.6-magnitude jolt in September 1999 that killed over 2,400 people. — Agencies