The Hualien earthquake swarms


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The Hualien city is located right at the pole of rotation induced by the along-strike transition from Ryukyu subduction to the collision between Luzon arc and the Chinese continental margin. This tectonic regime provides the seismogenic structures for the ruptures of the 1951 M 7.3 Hualien-Taitung one-month-long earthquake sequence, the recent 2018 Mw 6.4 Hualien earthquake sequence, and frequent and numerous moderate-to-small size earthquake swarms. On 18 April 2021, two earthquakes with ML 5.8 and 6.2, respectively, occurred at Shoufeng, 20 km southwest of Hualien. Even since, uninterrupted earthquake swarms followed from Shoufeng area to the Hualien city for about three months, up to 19 July, swarms continue.

Frequent small-to-moderate-size earthquakes may release minute strain energy for the small asperity or barrier located on the same or different fault zones, however, growing strain energy may also be accumulated at other deeper or nearby unbroken larger size asperities, for the circumstances such as the 1951 and the 2018 events. The frequent and copious Hualien earthquake swarms provide us a great opportunity to test the earthquake preparation, initiation, and migration processes, which are the key elements for the understanding of generation of large earthquakes. We welcome contributions from field investigations, seismology, structure geology, and geodesy, etc., for a better understanding of the nature of the Hualien earthquake swarms.


Guest Editors 

Ruey-Juin Rau
Department of Earth Sciences, National Cheng Kung University, Taiwan
(Executive Guest Editor, Email: This email address is being protected from spambots. You need JavaScript enabled to view it.)

Wen-Tzong Liang
Institute of Earth Sciences, Academia Sinica, Taiwan


Important dates

Manuscript submission deadline: February 28, 2022

Revision in final form: August 1, 2022

Submit to the TAO office: September 1, 2022

Tentative publication: October, 2022


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