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计算了伊豆-小笠原、马里亚纳弧段的浅源地震与俯冲速率的相关系数,证实了俯冲速率是一个重要的控制因素。地震统计结果展示马里亚纳中深度(60~300km)地震存在较明显分段性,且与海底地形起伏度相对应,推断这种现象一方面因为海山俯冲引起的板块破裂程度高,导致更多的流体供应所致;另一方面可能与海山俯冲机制导致板片局部变形有关。通过全球P波波速模型,提取马里亚纳之下大约8.0km/s的等值面,揭示了俯冲板片的深部形态,在马里亚纳弧的南北两侧之下,存在两个明显的缺失,代表了板片深部的撕裂,且北部撕裂程度要比南部高,可能与北部小笠原高原与南部卡罗琳洋中脊俯冲有关。重力数据与地震数据揭示了相对于马里亚纳俯冲带北部,南部可能为强耦合,菲律宾海板块之下410~660km不连续界面滞留为太平洋板片,西南部与马里亚纳俯冲带南部俯冲太平洋板片相连。初步推断这种结构与具有较大浮力的卡罗琳洋中脊可能共同决定了马里亚纳俯冲带南部8°N、137.3°E存在的旋转极。
The correlation coefficients between the shallow earthquakes and the subduction velocities of the Izu-Ogasawara and Mariana arcs are calculated, and it is confirmed that the subduction rate is an important control factor. Seismic results show that the middle-depth (60-300 km) earthquakes in Mariana have obvious segmentality and correspond to the seafloor relief, which is inferred to be due to the high degree of plate rupture caused by the seamount subsidence Of the fluid supply; on the other hand may be related to seamount subduction caused by local deformation of the plate. Through the global P-wave velocity model, the equivalent surface of about 8.0 km / s under Mariana is extracted to reveal the deep morphology of the subducting slab. There are two obvious defects below the north-south Mariana arc , Which represents the tearing of the deep plate, and the northern tearing is higher than the south, possibly related to the subduction of the northern Origen plateau and the southern Caroline ridge. Gravity data and seismic data reveal strong coupling to the north and south of the Mariana subduction zone, with plate discontinuities of 410-660 km below the Philippine Sea plate remaining in the Pacific plate, southwestern subduction of the Mariana subduction zone in the Pacific Ocean Plate connected. It is preliminarily concluded that this structure and the Caroline ridge with large buoyancy may jointly determine the poles of rotation at 8 ° N and 137.3 ° E south of the subduction zone of Mariana.