Dependence of slip weakening distance (Dc) on final slip during dynamic rupture of earthquakes
Dependence of slip weakening distance (Dc) on final slip during dynamic rupture of earthquakes
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DOI：
10.1111/j.1365-246x.2009.04143.x
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发表时间：
2009-06
影响因子：
2.8
通讯作者：
E. Tinti;M. Cocco;E. Fukuyama;A. Piatanesi
中科院分区：
文献类型：
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作者：
E. Tinti;M. Cocco;E. Fukuyama;A. Piatanesi
在这项研究中，我们的目的是了解动态破裂传播过程中临界滑移弱化距离(Dc)与最终滑移(Dtot)的相关性以及它们推断的关联式的一致性。为了实现这一目标，我们进行了一系列适当的数值试验，以验证所采用的数值方法和实际测量Dc的能力。我们从遵循滑动弱化规律的自发动态破裂模型中反演了两个运动性破裂历史，其中分别假设断裂面上的Dc分布和Dc/Dtot比为常数。滑动速度和剪切牵引时间历史代表了我们打算重现的合成的“真实”目标数据。我们使用三维分裂结点牵引力数值程序，通过假设我们所建模的滑动速度作为断层面上的边界条件来成像动态牵引力演化。在我们的模拟尝试中，我们假设一个正则化的约夫函数作为震源时间函数，并从推断的牵引力-滑移曲线测量断层上每一点的临界滑移减弱距离。我们将推断的值与目标动态模型的值进行比较。我们的数值试验表明，仅对断层面上每一点目标模型的滑动速度函数进行拟合，不足以反演良好的牵引演化曲线和获得可靠的Dc测量。我们发现，Dc的估计对滑动速度函数的任何微小变化都非常敏感。假设断层上滑动速度为固定形状(即恒定上升时间和恒定正加速度时间)时，得到了与目标模型不同的Dc/Dtot之间的人为关联。我们指出，断裂能(击穿功)的估算不受测量Dc的偏差的影响。
SUMMARY In this study, we aim to understand the dependence of the critical slip weakening distance (D c) on the final slip (D tot) during the propagation of a dynamic rupture and the consistency of their inferred correlation. To achieve this goal we have performed a series of numerical tests suitably designed to validate the adopted numerical procedure and to verify the actual capability in measuring D c. We have retrieved two kinematic rupture histories from spontaneous dynamic rupture models governed by a slip weakening law in which a constant D c distribution on the fault plane as well as a constant D c/D tot ratio are assumed, respectively. The slip velocity and the shear traction time histories represent the synthetic ‘real’ target data which we aim to reproduce. We use a 3-D traction-at-split nodes numerical procedure to image the dynamic traction evolution by assuming our modelled slip velocity as a boundary condition on the fault plane. We assume a regularized Yoffe function as source time function in our modelling attempts and we measure the critical slip weakening distance from the inferred traction versus slip curves at each point on the fault. We compare the inferred values with those of the target dynamic models. Our numerical tests show that fitting the slip velocity functions of the target models at each point on the fault plane is not enough to retrieve good traction evolution curves and to obtain reliable measures of D c. We find that the estimation of D c is very sensitive to any small variation of the slip velocity function. An artificial correlation between D c/D tot is obtained when a fixed shape of slip velocity is assumed on the fault (i.e. constant rise time and constant time for positive acceleration) which differs from that of the target model. We point out that the estimation of fracture energy (breakdown work) on the fault is not affected by biases in measuring D c.