Slightly before 10.35 am local time (slightly before 2.35 am GMT) on Sunday 26 December 2012, an Earthquake measured as 5.9 on the Richter Scale at a depth of 22.4 km by the United States Geological Survey struck a mountainous region of southern Taiwan, causing shaking that was felt across much of the island. The shaking was apparently particularly severe in the southern city of Kaohsiung, where it caused buildings to sway severely for about 7 seconds, leading to widespread panic, though their does not appear to have been any significant damage or casualties.
Map of southern Taiwan, showing the epicenter of the quake, and the areas most severely shaken. United States Geological Survey.
Taiwan lies on the borders of two tectonic plates, the Philippine Sea Plate and the Eurasian Plate. The relationship between the two is quite complex, with the Eurasian plate being subducted under the Philippine Sea Plate in the south of the island, and along the Luzon trench, which extends south from the island to the Philippines, and the Philippine Sea Plate being subducted under the Eurasian Plate in the north of the Island, and along the Ryuku Trench which extends northeast from the island to Japan.
This leads to a large number of quakes on the island, though most do not do serious damage. The worst quake in recent times was in 1999, when an Earthquake in the center of the island killed over 2300 people.
See also Mapping the subductioin zone beneath Taiwan, Earthquake shakes Yamanashi Prefecture, Japan, Explosion on Suwanosejima, Earthquake in the Babuyan Islands of the Northern Philippines and Earthquakes on Sciency Thoughts YouTube.