The quake, which struck at 11:17 a.m. was centered 19.7 kilometers southeast of Yilan County Hall, at a depth of 17.5 km under the ocean floor, the CWB said. The highest intensity was recorded in Nan'ao, Yilan, at six, but only for 0.2 seconds, while other major areas in Yilan recorded an intensity of five, the CWB said.
In Taipei, the quake got up to an intensity of three for about 12 seconds. Chang Chien-hsing(???), a senior technical specialist at the CWB, said the magnitude 5.8 quake was amplified in the Okinawa trough and lasted a long time - 42.2 seconds in Taipei -- because it was shallow.
"There is possibility of small aftershocks and other earthquakes of similar magnitude over the next three days," he said, urging people to stay alert. The energy released by the earthquake was equivalent to one fourth that of an atomic bomb, due to the amplification of the seismic waves in the Okinawa trough, Chang said.
In Yilan, students ran out their classrooms in panic as buildings rocked and creaked, while goods fell off the shelves at several stores.
In Taipei, the windows of E. Sun bank in Zhongshan district cracked and the power went out on some streets. As of 4 p.m., however, there were no reports of serious damage or injuries. (By Worthy Shen, Huang Li-yun and Lilian Wu)