Earth Observatory Blog
Second Significant Earthquake to hit Taiwan this Month
A magnitude-7.2 deep earthquake occurred offshore northeastern Taiwan on 31 May 2016. This is the second significant quake to have struck northern Taiwan this month, and it was powerful enough to generate strong ground motion throughout the whole of northern Taiwan.
Unlike the shallow Ilan earthquake that had occurred earlier this month on 12 May 2016, the Central Weather Bureau of Taiwan estimated the hypocentre of today’s M 7.2 earthquake to be located approximately 270 km below the seafloor. This suggests that this event is likely to have occurred at the northward subducting slab of the Philippine Sea Plate.
The collision and subduction of the Philippine Sea Plate with the Eurasian Plate are responsible for the creation of the island of Taiwan for the past several million years.
A deep earthquake usually generates widespread ground motions as compared to a shallow-focused earthquake event. This effect becomes evident when comparing the 12-May and 31-May earthquake events. Although both earthquakes occurred in, what may be considered to be, the same region, the 12 May Ilan earthquake generated smaller and more concentrated ground motions than the 31 May earthquake. The ground motion from the 31 May earthquake was so wide in spread that nearly all of Taiwan felt the power of this deep event.