|dc.description.abstract||Luzon Arc has obliquely collided Eurasian Plate margin since Late Miocene, which has caused Taiwan orogeny, and formed a series of north-east/south-west reverse faults in northern Taiwan. When the orogeny moved southward, the northern part was collapsed after the orogeny, and the Okinawa Trough extends westward. Hence, the stress regime of the northern Taiwan has changed from compression to extension. Between the inland and offshore of Keelung, a fault is suggested in the offshore area but it is not extended to land. Moreover, there’s a group of Quaternary volcanoes, such as Tatun and Keelung volcanic groups. It’s interseting to study the relationship between the volcanism and the structural faults.
This study used Multi-beam Echo Sounder, Echo Sounder System, and Sub-bottom Profiler to study the seafloor, plume phenomenon, and the structure of faults beneath the seafloor in northern Taiwan. This study also used data gathered from Echo Sounder System and 17 Sub-bottom Profiler. In total, profiles of 76 kilometers were collected by using the R/V OR2 during the cruises 1806, 1814, 1815 and 1821. In this study, we focus on the area that contains gas plumes, detected by EK60 Echo Sounder. Our results show that there are gas plumes appeared near the Keelung Harbor.The cone-shaped seamount and its associated high density of earthquakes indicate the gas plumes are highly related to the volcanic activity. Finally, we did not observe a structural fault extending from the land to the offshore area of the seamount.