Preliminary Results of a Large Offset Seismic Survey West of Hengchun Peninsula,Southern Taiwan

南臺灣恒春半島西側大支距震測研究之初步結果

Yosio Nakamura ； Kirk D. McIntosh ； 陳讚煌(Allen T. Chen)

《Terrestrial, Atmospheric and Oceanic Sciences》 9卷3期 (1998/09) Pp. 395-408

並列摘要

Six ocean bottom seismographs(OBSs)were deployed along an eastwestseismic line at 22°12'N latitude in the eastern offshore region of southernTaiwan to record air-gun shots over the instruments.The line extendsfrom 122°00'E in the Philippine Sea Basin to 120°55'E near the HengchunPeninsula and crossed the North Luzon Arc,the North Luzon Trough,theHuatung Ridge and the Southern Longitudinal Trough,from east to west.A seismic velocity model along the profile derived from the acquired dataincludes two layers of sediments with a P-wave velocity of less than 3.6km/s and upper and lower crusts with velocities of up to 5.3km/s and 7.0km/s,respectively.The sediment layer is very thin on the North Luzon Arc andTrough,but is as thick as 5km under the Huatung Ridge and the SouthernLongitudinal Trough.The crust,which is about 6km thick under the PhilippineSea Basin,thickens westward and is more than 15km under theNorth Luzon Arc and again towards the Hengchun Peninsula,with correspondingvariations in Moho depth.The seismic structure in the area isthus consistent with a hypothesis that once a trench located along the SouthernLongitudinal Trough might retreat farther west at a later stage.

並列關鍵字

Southern Taiwan ； Crustal Structure ； Subduction/Collision ； Margin Wedge ； Ocean-Bottom Seismograph