Reduction of seismic velocities has been employed to study the hydration of incoming plates and forearc mantle in recent years. However, few constraints have been obtained in the Southern Mariana Trench. We use an ocean bottom seismograph (OBS) deployment to conduct Rayleigh wave tomographic studies to derive the SV-wave velocity structure near the Southern Mariana Trench. Measured group and phase velocities as a function of period are inverted to determine the SV-wave velocity using a Bayesian Monte Carlo algorithm. The incoming Pacific Plate is characterized by low velocities (3.6–4.1 km/s) within the upper ∼25 km of the mantle near the trench, indicating extensive mantle hydration of the incoming plate in southern Mariana. The velocity reduction in the forearc mantle is not as large as in central Mariana, most likely indicating a lower forearc serpentinization in this region, which is consistent with the absence of serpentinite mud volcanoes.

中文翻译：

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瑞利波断层扫描显示南马里亚纳海沟附近剪切速度降​​低表明上地幔水合

近年来，地震速度的降低已被用于研究来袭板块和弧前地幔的水合作用。然而，在南马里亚纳海沟中获得的限制很少。我们使用海底地震仪 (OBS) 部署进行瑞利波层析成像研究，以推导出南马里亚纳海沟附近的SV -波速结构。测量的群速度和相速度作为周期的函数被反转以确定SV -使用贝叶斯蒙特卡罗算法计算波速。传入太平洋板块的特征是海沟附近地幔上部约 25 公里内的低速度（3.6-4.1 公里/秒），表明在马里亚纳南部传入板块存在广泛的地幔水合。弧前地幔的速度降低不如马里亚纳中部那么大，很可能表明该地区弧前蛇纹石化程度较低，这与没有蛇纹岩泥火山相一致。