Kinematics and dynamics of the southeastern margin of the Tibetan Plateau
Kinematics and dynamics of the southeastern margin of the Tibetan Plateau
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DOI：
10.1111/j.1365-246x.2008.03853.x
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发表时间：
2008-09
影响因子：
2.8
通讯作者：
A. Copley
中科院分区：
文献类型：
--
作者：
A. Copley
摘要青藏高原东南缘有一大片地区，地震活动和GPS数据显示该地区正在发生活跃的变形。本文描述了该地区的活动断裂，以及它与GPS观测速度场的关系。在某些地方，速度场是通过绕垂直轴的旋转来调节的，该地区表面的大部分或全部应变似乎是通过地震释放的。然后将GPS速度与使用重力驱动力驱动的变形模型计算的速度进行比较。使用流变学估计从实验推导的矿物流动规律，该模型提供的速度与观测到的GPS速度是很好的协议。不可能唯一地确定深度处的流变学或流速，并且有两种形式的模型解与观察到的水平表面速度相匹配。在其中一个，垂直面变形的纯剪切，并在其他垂直梯度的水平速度存在于地壳内。该地区存在两个不同的正断层地震区，其机制最容易用重力驱动变形来解释。
SUMMARY On the southeastern margin of the Tibetan Plateau lies a large region which seismicity and GPS data show to be actively deforming. This paper describes the active faulting in the region, and how it relates to the velocity field observed with GPS. In places the velocity field is accommodated by rotations about vertical axes, and most or all of the strain at the surface in the region appears to be released seismically. GPS velocities are then compared to velocities calculated using a model for deformation driven by gravitational driving forces. Using rheologies estimated from experimentally derived mineral flow laws, the model provides velocities that are in good agreement with observed GPS velocities. It is not possible to uniquely determine the rheology or flow velocity at depth, and there are two forms of model solution which match the observed horizontal surface velocities. In one of these, vertical planes deform by pure shear, and in the other vertical gradients of horizontal velocity are present within the crust. Two distinct regions of normal-faulting earthquakes are present in the region, and have mechanisms which are most easily explained by gravity-driven deformation.