Earthquakes near oceanic trenches are important for studying incoming plate bending and updip thrust zone seismogenesis, yet are poorly constrained using seismographs on land. We use an ocean bottom seismograph (OBS) deployment spanning both the incoming Pacific Plate and the forearc to study seismicity near the Mariana Trench. The yearlong deployment in 2012‐2013 consisted of 20 broadband OBSs and 5 suspended hydrophones, with an additional 59 short period OBSs and hydrophones recording for one month. We locate 1,692 earthquakes using a nonlinear method with a 3D velocity model constructed from active source profiles and surface wave tomography results. Events occurring seaward of the trench occur to depths of ~35 km below the seafloor, and focal mechanisms of the larger events indicate normal faulting corresponding to plate bending. Significant seismicity emerges about 70 km seaward from the trench and the seismicity rate increases continuously towards the trench, indicating that the largest bending deformation occurs near the trench axis. These plate‐bending earthquakes occur along faults that facilitate the hydration of the subducting plate, and the lateral and depth distribution of earthquakes is consistent with low velocity regions imaged in previous studies. The forearc is marked by a heterogeneous distribution of low magnitude (< 5 M_w) thrust zone seismicity, possibly due to the rough incoming plate topography and/or serpentinization of the forearc. A sequence of thrust earthquakes occurs at depths ~10 km below seafloor and within 20 km of the trench axis, demonstrating that the megathrust is seismically active nearly to the trench.

中文翻译：

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海底地震仪记录的马里亚纳海沟附近传入板块和前臂的地震活动

海洋海沟附近的地震对于研究传入的板块弯曲和上冲推力带地震发生很重要，但在陆地上使用地震仪很难加以约束。我们使用跨越即将到来的太平洋板块和前臂的海底地震仪（OBS）来研究马里亚纳海沟附近的地震活动。2012-2013年的一年部署包括20个宽带OBS和5台悬挂式水听器，另外还有59个短期OBS和水听器记录一个月。我们使用非线性方法定位了1,692处地震，该非线性方法是根据主动震源剖面和表面波层析成像结果构造的3D速度模型。发生在海槽海面的事件发生在海底以下约35 km的深度，较大事件的震源机制表明与板块弯曲相对应的正断层。从沟槽向海约70 km处会出现明显的地震活动，并且地震活动率朝着沟槽不断增加，这表明最大的弯曲变形发生在沟槽轴线附近。这些板块弯曲的地震发生在有利于俯冲板水化的断层上，地震的横向和深度分布与先前研究中所成像的低速区域一致。前臂的特征是低强度（<5 M 地震的横向和深度分布与先前研究中所成像的低速区域一致。前臂的特征是低强度（<5 M 地震的横向和深度分布与先前研究中所成像的低速区域一致。前臂的特征是低强度（<5 M_w）推力区的地震活动性，可能是由于前板的粗糙的入波地形和/或蛇形的。在海底以下约10 km处且在沟槽轴线的20 km以内，发生了一系列的推力地震，表明兆推力几乎对沟槽具有地震活动性。