Absolute tectonic stress estimation is of fundamental importance to investigating regional earthquake hazards, while traditional algorithms only invert relative stress and its orientations. We use topography data and rupture models to invert the absolute tectonic stress in the source region of the 2016 M_w 7.0 Kumamoto earthquake. We adopt a basic assumption that the slip direction of each sub-fault is in the shear direction of the total stress tensor, which is a combination of tectonic and topographic stresses. We use the Bayesian theorem to describe the probability density function of stress parameters and perform a grid search for the optimal values and uncertainties of stress parameters. Our synthetic test shows that the true parameters can be reliably estimated over a broad range of tectonic stress magnitudes. In the application to the Kumamoto earthquake, we find that the optimal tectonic stress is uniaxial tensional with a magnitude of 35 MPa and orientation of N6.5°W, which is at an angle of ∼47.5° to the fault strike. The average total shear stress on the fault plane is 16 MPa on the fault plane. With the inverted stress parameters, we evaluate the pore pressure based on the absolute stress field, the result of which is within a range of 0.3–0.45 of the lithostatic stress.

中文翻译：

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使用地形和破裂模型反演 2016 Mw 7.0 熊本地震震源区的绝对构造应力

绝对构造应力估计对于调查区域地震灾害具有重要意义，而传统算法仅反转相对应力及其方向。我们使用地形数据和破裂模型来反演 2016 M _w源区的绝对构造应力7.0熊本地震。我们采用一个基本假设，即每个子断层的滑动方向为总应力张量的剪切方向，是构造应力和地形应力的组合。我们使用贝叶斯定理来描述应力参数的概率密度函数，并对应力参数的最优值和不确定性进行网格搜索。我们的综合测试表明，可以在广泛的构造应力大小范围内可靠地估计真实参数。在熊本地震的应用中，我们发现最优构造应力为单轴拉张应力，震级为35 MPa，方位为N6.5°W，与断层走向成约47.5°角。断层面上的平均总剪应力为 16 MPa。用倒置的应力参数，