Introduction To The Special Issue On The 2018 Hualien, Taiwan, Earthquake

Exactly two years after the 2016 Mw 6.5 Meinong event, an Mw 6.4 earthquake occurred slightly offshore Hualien at about 16 km NNE of the Hualien city with a focal depth of 6.3 km on 6 February 2018 (23:50:41.6 local time). It is a moderate-sized event, however, produced strong shaking in the Hualien city, triggered and ruptured the Milun fault, which was previously activated during the 1951 M 7.3 Hualien-Taitung earthquake sequence (e.g., Chen et al. 2008). The 2018 event caused several buildings along the Milun fault collapsed and 17 deaths. At the end of 2015, the Taiwan Earthquake Model (TEM) announced a seismic hazard map of Taiwan indicating a relatively high seismic hazard in both Tainan and Hualien (Rau and Ma 2016; Wang et al. 2016). The occurrences of the 2016 Meinong event and the 2018 Hualien event validate and strengthen the importance of the seismic hazard map proposed by TEM (Rau and Liang 2017). With the extremely high strain rate, 10-7 - 10-6, and therefore short earthquake recurrence intervals in Taiwan, reactivations of any pre-existing structures in this highly deformed crust are immensely anticipated in the foreseeable future.