Chin S.-J.Lin J.-Y.Yeh Y.-C.Kuo-Chen H.Liang C.-W.HAO KUO-CHEN2022-06-302022-06-30201913679120https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060716936&doi=10.1016%2fj.jseaes.2019.01.014&partnerID=40&md5=ad56a07b8ff47a79f119aa63943d1695https://scholars.lib.ntu.edu.tw/handle/123456789/614563Based on the distribution of an earthquake swarm determined from an ocean bottom seismometer (OBS) network deployed from 20 August to 5 September 2015 in the northernmost part of the South China Sea (SCS) and data from inland seismic stations in Taiwan, we resolved a M L 4.1 earthquake occurring on 1 September 2015 as a NE-SW-trending left-lateral strike-slip event that ruptured along the pre-existing normal faults generated during the SCS opening phases. The direction of the T-axes derived from the M L 4.1 earthquake and the background seismicity off SW Taiwan present high consistency, indicating a stable dominant NW-SE tensional stress for the subducted Eurasian Plate (EUP). The distinct stress variations on the two sides of these reactivated NE-SW trending features suggest that the presence of pre-existing normal faults and other related processes may lessen the lateral resistance between the Taiwan collision and Manila subduction system, and facilitate the slab-pull process for the subducting portion, which may explain the NW-SE tensional stress environment near the transition boundary in the northernmost part of the SCS. © 2019 Elsevier Ltdcollision zone; earthquake swarm; Eurasian plate; normal fault; passive margin; seismograph; seismotectonics; strike-slip fault; subduction; Manila; National Capital Region; Philippines; Taiwanjournal article10.1016/j.jseaes.2019.01.0142-s2.0-85060716936