Conductivity structure around seismogenic layer beneath the Chugoku and Shikoku districts

我们在这一研究中使用了电磁方法的菲律宾海板，该网络-MT方法是一种磁性方法，它是适合于调查一个操作性结构，一个宽区域和一个深区域。我们在Chugoku和Shikoku地区应用了一种方法，以揭示日本西南部的地下表面结构。我们把注意力集中在菲律宾海的地方和如何存在的地方。第一个原因是，菲律宾海板的位置是一个最重要的因素，因为地震的冷和刚性板会造成更大的影响，因为它们对热状态和/或微波速度的分布。第二个原因是，这很难确定盘子的位置，只使用海洋学方法。精确的2-维度行为模型已经建立。该模型由以下点特征化：1）北滴抵抗层（> 500Ω·m）存在Chugoku和Shikoku地区。抵抗层的上深度为20公里，30公里，位于Shikoku地区的南部和北部部分，位于Shikoku地区的40公里，位于60公里，位于Chugoku地区的南部和北部部分，对此表示赞赏。2） Conductive layer （~100Ω·m） exists beneath the north dipping resistive layer。3）在40公里深的地方发现了一个高度敏感的层，该层位于Chugoku地区的北部最大部分。我们解释了菲律宾海板的北滴抵抗力层。

We delineated the Philippine Sea plate beneath the South-western Japan arc using the electro-magnetic method in this study.The Network-MT method is one of the magnetotelluric methods and it is suitable for surveying a conductivity structure beneath a wide area and to a deep portion. We applied the method in Chugoku and Shikoku district to reveal a subsurface structure beneath the South-west Japan arc. We focused on the where and how does the Philippine Sea Plate exist. The first reason is that a location of The Philippine Sea plate is most important factor to controlled occurrences of earthquakes, because the cold and rigid plate makes large influence on a thermal state and/or a distribution of seismic-wave velocity. Second reason is that it is hard to decide a location of the plate using only seismic methods.The precise 2-dimensional conductivity model was established. This model is characterized by following points.1) North dipping resistive layer (> 500Ω・m) exists beneath both Chugoku and Shikoku districts. The upper depth of the resistive layer is 20km, 30km beneath the southern and northern part of the Shikoku district, and 40km, 60km beneath the southern and northern part of the Chugoku district, respectively. 2) Conductive layer (~100Ω・m) exists beneath the north dipping resistive layer. 3) Highly conductive layer is found at 40km-depth beneath the northern most part of the Chugoku district. We interpreted the north dipping resistive layer is the Philippine Sea plate.