Mantle subducting slab structure in the region of the 2010 M8.8 Maule earthquake (30–40°S), Chile
Mantle subducting slab structure in the region of the 2010 M8.8 Maule earthquake (30–40°S), Chile
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DOI：
10.1111/j.1365-246x.2012.05624.x
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发表时间：
2012-10
影响因子：
2.8
通讯作者：
J. Pesicek;E. Engdahl;C. Thurber;H. DeShon;D. Lange
中科院分区：
文献类型：
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作者：
J. Pesicek;E. Engdahl;C. Thurber;H. DeShon;D. Lange
我们提出了2010年茂勒8.8级地震及周边地区地幔的新层析模型。余震数据提供的更大的射线覆盖率使我们能够成像地幔中详细的俯冲板结构，从Maule破裂以北的平板俯冲区域到1960年M9.5和2010年M8.8事件之间的重叠断裂区域。我们将远震初级和深度震相到达与可用的本地到达相结合，以更好地约束该地区的远震地震位置，我们使用这些地点进行嵌套的区域-全球层析成像。新的模型揭示了平板的详细结构，以及它向毛勒地区更中等倾角的平板的过渡。在毛勒地区南部，一个陡峭的遗迹板在∼200到1000公里深的地方被成像，这与它上面的中等倾角的板和类似深度的更北的板不同。我们将这些图像解释为揭示了∼38°S的板条水平和垂直撕裂，以解释模型南部板块异常的成像模式。相比之下，模型北部从水平向中度俯冲的楼板的过渡被成像为连续的楼板弯曲。我们推测，这种撕裂很可能是由下行板块中的断裂带促成的，或者是由覆盖板块中的大陆尺度地体边界促成的。
We present a new tomographic model of the mantle in the area of the 2010 M8.8 Maule earthquake and surrounding regions. Increased ray coverage provided by the aftershock data allows us to image the detailed subducting slab structure in the mantle, from the region of flat slab subduction north of the Maule rupture to the area of overlapping rupture between the 1960 M9.5 and the 2010 M8.8 events to the south. We have combined teleseismic primary and depth phase arrivals with available local arrivals to better constrain the teleseismic earthquake locations in the region, which we use to conduct nested regional–global tomography. The new model reveals the detailed structure of the flat slab and its transition to a more moderately dipping slab in the Maule region. South of the Maule region, a steeply dipping relic slab is imaged from ∼200 to 1000 km depth that is distinct from the moderately dipping slab above it and from the more northerly slab at similar depths. We interpret the images as revealing both horizontal and vertical tearing of the slab at ∼38°S to explain the imaged pattern of slab anomalies in the southern portion of the model. In contrast, the transition from a horizontal to moderately subducting slab in the northern portion of the model is imaged as a continuous slab bend. We speculate that the tearing was most likely facilitated by a fracture zone in the downgoing plate or alternatively by a continental scale terrane boundary in the overriding plate.