Fluid Controls on the Heterogeneous Seismic Characteristics of the Cascadia Margin
Fluid Controls on the Heterogeneous Seismic Characteristics of the Cascadia Margin
复制标题
卡斯卡迪亚边缘非均质地震特征的流体控制
DOI：
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发表时间：
2018
影响因子：
5.2
通讯作者：
F. Niu
中科院分区：
文献类型：
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作者：
J. Delph;A. Levander;F. Niu
大洋板块在俯冲过程中的脱水主要受热控制，通常表现为中深度地震活动。在温暖的俯冲带，浅层脱水也会导致板块界面附近孔隙流体压力的积聚，从而导致非火山性震颤。在卡斯卡迪亚边缘，尽管胡安-德-富卡板块的热结构变化不大，但地震密度和中深度地震活动性相互关联，但从南到北变化显著。在卡斯卡迪亚北部和南部边缘，中深度地震活动性可能对应于流体通量的增加，而地震密度的增加可能是由于流体渗入到以非常慢的横波速度（<3.2 km/s）为特征的厚逆冲下沉积。在卡斯卡迪亚中部，较低的中深度地震活动性和地震密度可能表明流体通量较低，而横波速度表明Siletzia地块延伸到板块界面。这些结果表明，厚逆冲下沉积的存在与地震发生的增加有关。
The dehydration of oceanic slabs during subduction is mainly thermally controlled and is often expressed as intermediate‐depth seismicity. In warm subduction zones, shallow dehydration can also lead to the buildup of pore‐fluid pressure near the plate interface, resulting in nonvolcanic tremor. Along the Cascadia margin, tremor density and intermediate‐depth seismicity correlate but vary significantly from south to north despite little variation in the thermal structure of the Juan de Fuca Plate. Along the northern and southern Cascadia margin, intermediate‐depth seismicity likely corresponds to increased fluid flux, while increased tremor density may result from fluid infiltration into thick underthrust metasediments characterized by very slow shear wave velocities (<3.2 km/s). In central Cascadia, low intermediate‐depth seismicity and tremor density may indicate a lower fluid flux, and shear wave velocities indicate that the Siletzia terrane extends to the plate interface. These results indicate that the presence of thick underthrust sediments is associated with increased tremor occurrence.