We estimate seismic azimuthal anisotropy for the Juan de Fuca - Gorda plates from inversion of a new 10–80 s period Rayleigh wave dataset, resulting in a two-layer model to 80 km depth. In the lithosphere, most anisotropy patterns reflect the kinematics of plate formation, as approximated from seafloor-age-based paleo-spreading, except for regions close to propagator wakes and near plate boundaries. In the asthenosphere, the fast propagation orientations align with convective shear as inferred from the NUVEL1A plate motion model, which is indicative of a ∼3 Myr average, rather than with the more recent, ∼0.8 Myr, motions inferred from MORVEL. Regional anisotropy of this young plate system thus records convection like older plates such as the Pacific. On smaller scales, anisotropy imaging provides insights into dynamics of plate generation and can further elucidate plate reorganizations and changes in boundary loading.

中文翻译：

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Juan de Fuca - Gorda 板块系统内的地震方位各向异性


我们通过反演新的 10-80 s 周期瑞利波数据集来估计 Juan de Fuca - Gorda 板块的地震方位各向异性，从而得到一个深度为 80 公里的两层模型。在岩石圈中，大多数各向异性模式反映了板块形成的运动学，从基于海底年龄的古扩散近似得出，除了靠近传播器尾迹和靠近板块边界的区域。在软流圈中，快速传播方向与从NUVEL1A板运动模型推断的对流切变一致，这表明 ∼3 Myr 平均值，而不是从 MORVEL 推断出的最新 ∼0.8 Myr 运动。因此，这个年轻板块系统的区域各向异性记录了与太平洋等老板块一样的对流。在较小的尺度上，各向异性成像提供了对板生成动力学的见解，并可以进一步阐明板的重组和边界载荷的变化。