Lithospheric flexure under the Hawaiian volcanic load: Internal stresses and a broken plate revealed by earthquakes
Lithospheric flexure under the Hawaiian volcanic load: Internal stresses and a broken plate revealed by earthquakes
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夏威夷火山载荷下的岩石圈弯曲：地震揭示的内应力和破碎板块
DOI：
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
F. Klein
中科院分区：
文献类型：
--
作者：
F. Klein
几条地震线的证据表明，岩石圈板块在夏威夷岛的负荷下破裂，那里的岩石圈几何形状是圆形的，中央有一个凹陷。接骨板围绕无应力孔向下弯曲，而不是像过去假设的那样向上弯曲。震源机制表明，载荷应力中心和弱洞位于载荷最大的莫纳罗亚山和莫纳克亚山峰顶之间。21 km深度处的地震空区与预测的水平应力变化标志的挠曲中性面相吻合。中性面以下的震源机制P轴显示出指向应力中心的显著放射状图案。在该岛北部中性面以上的地震有相反的应力模式; T轴倾向于径向。M6.2 Honomu和M6.7 Kiholo主震（均位于39 km深度）位于中性面以下，显示径向压缩，中性面以上的M6.0 Kiholo余震具有切向压缩。深度超过20公里的地震定义了应力中心周围的地震活动圈，其中弯曲度最大。这个洞被解释为岩石圈板块破裂的软中心。基拉韦厄的深层管道是地震活跃的，因为它处于最大弯曲的环中。一端有荷载的弯曲板的简化二维应力模型产生的应力方向与地震应力轴和中性面以下的径向P轴一致。先前对夏威夷深部震源机制的反演发现了一个与模型一致的围绕应力中心的圆形解。对于水平断层，弯曲板内的剪切应力与基拉韦厄地震带深部的滑动相匹配，并增强了活动侧翼的向外滑动。
Several lines of earthquake evidence indicate that the lithospheric plate is broken under the load of the island of Hawai`i, where the geometry of the lithosphere is circular with a central depression. The plate bends concave downward surrounding a stress‐free hole, rather than bending concave upward as with past assumptions. Earthquake focal mechanisms show that the center of load stress and the weak hole is between the summits of Mauna Loa and Mauna Kea where the load is greatest. The earthquake gap at 21 km depth coincides with the predicted neutral plane of flexure where horizontal stress changes sign. Focal mechanism P axes below the neutral plane display a striking radial pattern pointing to the stress center. Earthquakes above the neutral plane in the north part of the island have opposite stress patterns; T axes tend to be radial. The M6.2 Honomu and M6.7 Kiholo main shocks (both at 39 km depth) are below the neutral plane and show radial compression, and the M6.0 Kiholo aftershock above the neutral plane has tangential compression. Earthquakes deeper than 20 km define a donut of seismicity around the stress center where flexural bending is a maximum. The hole is interpreted as the soft center where the lithospheric plate is broken. Kilauea's deep conduit is seismically active because it is in the ring of maximum bending. A simplified two‐dimensional stress model for a bending slab with a load at one end yields stress orientations that agree with earthquake stress axes and radial P axes below the neutral plane. A previous inversion of deep Hawaiian focal mechanisms found a circular solution around the stress center that agrees with the model. For horizontal faults, the shear stress within the bending slab matches the slip in the deep Kilauea seismic zone and enhances outward slip of active flanks.
影响因子：
3.9
作者：
Zhong, Shijie;Watts, A. B.
通讯作者：
Watts, A. B.