Present-day crustal motion along the Longitudinal Valley Fault
Present-day crustal motion along the Longitudinal Valley Fault
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DOI：
10.1016/s0040-1951(00)00275-4
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发表时间：
2001-04
期刊：
影响因子：
--
通讯作者：
Shui Yu;B. Kuo
中科院分区：
文献类型：
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作者：
Shui Yu;B. Kuo
台湾东部北北东走向的纵谷断层（LVF）是一条极其活跃的高角度逆冲断层。它以海岸山脉和纵向山谷为界，被认为是菲律宾海和欧亚板块之间的碰撞边界。利用1992年至1999年在纵谷地区重复的GPS数据研究了地壳运动沿LVF的空间变化。对于中国大陆边缘的澎湖来说，LVF（纵谷和东部中央山脉）西侧的站，在283-311°方向上的速度为18-35毫米/年，而LVF东侧（海岸山脉）在303-324°方向上的速度为28-68毫米/年。正如先前的三边测量数据所揭示的，纵谷地壳运动速率约 30 毫米/年的主要不连续性归因于沿 LVF 的抗震滑移。在凤坪以南，沿海山脉相对于中央山脉在317°～330°的块体运动为31～40mm/年，而在309°～336°的近断层运动为13～33mm/年。沿 LVF 发现了左旋走滑和汇聚分量上的各种分区。纵谷南部地壳运动主要受LVF和鹿野断层的调节。相比之下，纵谷中部和北部的那些则部分占据了LVF以东的断层或导致了海岸山脉的弹性变形。北部纵谷地区的地壳运动很可能呈马尾状分布在几个北东向的逆冲断层中，并斜切北部海岸山脉，其中有一小部分断层滑沿沿LVF。来自 LVF 上密集部署的 GPS 网络的数据可用于更好地估计近断层运动并描绘 LVF 的表面痕迹。玉里大桥两端相距575m的两个站点的重复GPS和水准测量数据清楚地表明，LVF的地表轨迹以306°的斜水平运动23mm/年和24mm/年的抬升率从桥下通过。
The NNE-striking Longitudinal Valley Fault (LVF) in eastern Taiwan is an extremely active high-angle thrust fault. It bounds the Coastal Range and the Longitudinal Valley, which is considered a collision boundary between the Philippine Sea and the Eurasian plates. Repeated GPS data in the Longitudinal Valley area from 1992 to 1999 are utilized to study the spatial variation of crustal motion along the LVF. With respect to Penghu in the Chinese continental margin, velocities for stations on the western side of the LVF (Longitudinal Valley and eastern Central Range) are 18–35mm/yr in directions 283–311°, whereas those on the eastern side of the LVF, the Coastal Range, are 28–68mm/yr in directions 303–324°. A major discontinuity of about 30mm/yr on the rate of crustal motion across the Longitudinal Valley is attributed to the aseismic slip along the LVF as revealed by trilateration data previously. To the south of Fengping, the block motions of the Coastal Range are 31–40mm/yr in 317–330° relative to the Central Range, while the near-fault motions are 13–33mm/yr in 309–336°. Various partitions on the left-lateral strike-slip and convergent components along the LVF are found. In the southern Longitudinal Valley crustal motion is mainly accommodated on the LVF and the Luyeh Fault. In contrast, those in the central and northern Longitudinal Valley are partly taken up on the faults to the east of the LVF or result in the elastic deformation of the Coastal Range. The crustal motion in the northern Longitudinal Valley area is likely to be distributed in the several NE-striking thrusts in a horsetail pattern and obliquely cut the northern Coastal Range, with a small portion of fault-slips along the LVF. Data from dense-deployed GPS networks across the LVF can be employed to give better estimates of near-fault motions and delineate the surface traces of the LVF. Repeated GPS and leveling data from two stations on both ends of the Yuli Bridge that are 575m apart clearly indicate that the surface trace of the LVF passes beneath the bridge with oblique horizontal motion of 23mm/yr in 306° and uplift rate of 24mm/yr.