A powerful earthquake measuring 7.0 on the Richter Scale shook Taiwan, sparkling several fires and prompting people to flee swaying high-rise buildings but causing no serious damage. The quake led to a dozen technicians being trapped in elevators of the world's tallest building, Taipei 101, for several minutes but the 508-metre (1,666-feet) structure remained intact, passing a key safety test. The earthquake struck shortly after noon (0408 GMT) and was also felt in Japan's southern Okinawa chain, where the Meteorological Agency said it measured 6.6 on the Richter Scale. Neither Taiwan nor Okinawa reported serious injuries or damage from the tremor, which was located at sea some 109 kilometres (68 miles) off Taiwan's northeastern coast. Its focus was 58 kilometres below sea level. Its strength was "equivalent to 16 atomic bombs," Taiwan Seismology Centre director Kuo Kai-wen said. "The epicenter originated from the sea and its destructive strength was greatly reduced," Kuo said. It was the largest earthquake to hit quake-prone Taiwan since the island's worst one struck on September 21, 1999, measuring 7.6 on the Richter Scale and leaving about 2,400 people dead. Friday's tremor shook high-rise buildings in the capital Taipei, sending panicked people fleeing to the street and leading to a 30-minute suspension of the city's underground transport system.