The Taiwan Central Weather Bureau reported a Magnitude 5.6 Earthquake at a depth of 18.4 km 12.2 km to the southwest of Tainan City in southwest Taiwan slightly after 1.10 am local time on Saturday 11 February 2017 (slightly after 5.10 pm on Friday 10 February GMT). The event was felt across much of west and central Taiwan, and while there was no major damage associated with this event, four people reportedly suffered injuries due to falling objects.
The approximate location of the 11 February 2017 Tainan Earthquake. USGS.
Taiwan has a complex tectonic setting, lying on the boundary between the Eurasian and Philippine Plates, with the Eurasian Plate being subducted beneath the Philippine Plate in the South and the Philippine Plate being subducted beneath the Eurasian in the East. Subduction is not a smooth process even in simple settings, with plates typically sticking together as pressure from tectonic expansion elsewhere builds up, then suddenly breaking apart and shifting abruptly, causing Earthquakes.
The motion of the tectonic plates beneath Taiwan. The University of Memphis.
Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.