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虽然台湾西部的造山运动逐渐减弱,但台湾海峡的确还发生大、小地震。主要由于后勤原因,以前的研究基本没触及该地区。然而该地区的整体地壳构造具有特殊意义,因为它可能提供造山运动之前原始台湾的线索。通过将使用台站对从环境地震噪声提取的时域经验格林函数(TDEGF)与传统面波双台法(TS)相结合,我们能构建出5~120s之间的瑞雷波相速度频散曲线。使用台湾和海峡两岸的台湾宽频带地震台阵(BATS)的台站,我们能够获得该地区不同地方的平均一维V S结构。如预期所料,结果显示在地壳上部15km内有显著的剪切波速度差异。总的来说,中国大陆沿海地区上地壳和台湾岛西南海域上地壳分别出现最高V S和最低V S,它们相差约0.6~1.1km/s。对于海峡的不同地方,海峡中部上地壳V S结构比北部和南部低约0.1~0.2km/s。台湾海峡地下的上地幔V S结构(莫霍面-150km)比AK135模型低约0.1~0.3km/s。整体地壳厚度约为30km,比台湾岛下的地壳厚度更薄且变化更小。使用水深超过1 000m海域中的短周期频散数据反演地震波速度结构除大陆架外还应将水层考虑进去。
Although the orogeny in western Taiwan gradually weakened, large and small earthquakes did indeed occur in the Taiwan Strait. Mainly due to logistical reasons, the previous research basically did not touch the area. However, the overall crustal structure in the area is of special significance as it may provide clues to primitive Taiwan before the orogeny. By combining the time-domain empirical Green’s function (TDEGF) extracted from ambient seismic noise with the traditional surface-wave two-station method (TS) using stations, we can construct a Rayleigh wave velocity dispersion between 5 and 120 s curve. Using Taiwan’s Broadband Seismic Array (BATS) stations across Taiwan and the Taiwan Strait, we were able to obtain average one-dimensional V S structures in different parts of the region. As expected, the results show significant shear wave velocity differences within 15 km above the crust. In general, the highest V s and the lowest V s appear in the upper crust of China’s coastal area and the upper crust of the southwestern Taiwan island, respectively, which differ by about 0.6-1.1 km / s. For different parts of the Strait, the V s structure of the upper crust of central Strait is about 0.1 ~ 0.2 km / s lower than the north and south. The V s structure of the upper mantle beneath the Taiwan Strait (Moho-150km) is about 0.1 ~ 0.3km / s lower than the AK135 model. The overall crustal thickness is about 30 km, which is thinner and less variable than the crust beneath the island of Taiwan. Inversion of seismic velocity structures using short-period dispersion data in waters over 1 000 m depth should be taken into account in addition to the continental shelf.