Surface wave tomography for the Pacific Ocean incorporating seafloor seismic observations and plate thermal evolution
Surface wave tomography for the Pacific Ocean incorporating seafloor seismic observations and plate thermal evolution
复制标题
结合海底地震观测和板块热演化的太平洋表面波层析成像
DOI：
10.1016/j.epsl.2018.12.033
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发表时间：
2019
影响因子：
5.3
通讯作者：
Reymond Dominique
中科院分区：
文献类型：
--
作者：
Isse Takehi;Kawakatsu Hitoshi;Yoshizawa Kazunori;Takeo Akiko;Shiobara Hajime;Sugioka Hiroko;Ito Aki;Suetsugu Daisuke;Reymond Dominique
利用200多台宽带海底地震仪在海底记录的宽带地震波形，以及陆地上记录的宽带地震波形，我们测量了Love波和Rayleigh波到4阶高阶模态的相速度频散，以确定太平洋上地幔三维径向各向异性剪切波速度结构。在100 km以下深度的最快异常位于沙茨基海隆东南下方，强径向各向异性位于中太平洋100-200 km深度。各向同性剪切波速度结构表现出年龄依赖性。从年龄箱平均剪切波速度剖面和半空间冷却模型，我们估计了太平洋板块的热-速度关系，以构建一个参考年龄相关的剪切波速度模型，这是进一步用作层析成像迭代的初始模型。太平洋与参考模型的偏差图表明，大的负残差（可能是由于部分熔融、滞弹性和/或地幔柱增加的热量）位于沿着洋脊和热点之下，而大的正残差位于西北太平洋之下。使用的年龄相关的参考模型，以及OBS数据的纳入，大大提高了局部相速度估计在断层扫描的准确性，从直接比较内situarray测量明显。
Using broadband seismic waveforms recorded on the seafloor by more than 200 broadband ocean bottom seismometers, as well as those on land, we measured the phase speed dispersions of Love and Rayleigh waves up to the 4th higher mode to determine the three-dimensional radially anisotropic shear-wave speed structure in the upper mantle beneath the Pacific Ocean. The fastest anomalies at depths shallower than 100 km were located beneath southeast of the Shatsky Rise and strong radial anisotropy was located in the central Pacific at depths of 100–200 km. The isotropic shear-wave speed structures showed age dependence. From the age-bin-averaged shear-wave speed profiles and a half-space cooling model, we estimated the thermo-speed relationship for the Pacific Plate to construct a reference age-dependent shear-wave speed model, which was further used as an initial model for tomography iteration. Deviation maps in the Pacific Ocean from the reference model indicated that large negative residuals, which may be due to partial melting, anelasticity, and/or added heat from mantle plumes, were located along the ridges and beneath hotspots, and that large positive residuals were found beneath the northwestern Pacific Ocean. The use of an age-dependent reference model, as well as the incorporation of OBS data, greatly improves the accuracy of local phase speed estimates in tomography, as evident from a direct comparison within situarray measurements.