Slip complexity in earthquake fault models
Slip complexity in earthquake fault models
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DOI：
10.1073/pnas.93.9.3811
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发表时间：
1996-04-30
影响因子：
11.1
通讯作者：
Ben-Zion, Y
中科院分区：
文献类型：
--
作者：
Rice, JR;Ben-Zion, Y
我们总结了地震断层模型的研究，引起了像那些在自然地震的滑动复杂性。对于弹性变形连续体之间的光滑断层模型，摩擦定律必须包含滑动弱化或表面状态演化的特征距离。这导致有限的成核尺寸或相干滑移斑尺寸h*。光滑故障的模型，使用数值细胞大小适当小相比h*，显示周期性响应或复杂的，显然是大事件的混沌历史，但尚未发现显示小事件的复杂性，如自相似（幂律）古腾堡-里希特频率大小统计。这一结论得到了地震序列全惯性弹性动力学模拟的支持。相比之下，一些具有准独立故障段的局部非均质故障的模型，近似地由单元尺寸大于h* 的模拟表示，使得模型变得“固有离散”，确实显示出古登堡-里希特类型的小事件复杂性。基于经典摩擦定律的模型，没有弱化长度尺度，或者在滑移开始时数值程序施加突然的强度下降，h* = 0，因此总是属于固有的离散类。我们建议，小事件的复杂性，一些这样的模型显示将无法生存的本构描述的正则化，包括一个适当的长度尺度导致有限的h*，并相应地减少数值网格大小。
We summarize studies of earthquake fault models that give rise to slip complexities like those in natural earthquakes. For models of smooth faults between elastically deformable continua, it is critical that the friction laws involve a characteristic distance for slip weakening or evolution of surface state. That results in a finite nucleation size, or coherent slip patch size, h*. Models of smooth faults, using numerical cell size properly small compared to h*, show periodic response or complex and apparently chaotic histories of large events but have not been found to show small event complexity like the self-similar (power law) Gutenberg-Richter frequency-size statistics. This conclusion is supported in the present paper by fully inertial elastodynamic modeling of earthquake sequences. In contrast, some models of locally heterogeneous faults with quasi-independent fault segments, represented approximately by simulations with cell size larger than h* so that the model becomes ''inherently discrete,'' do show small event complexity of the Gutenberg-Richter type. Models based on classical friction laws without a weakening length scale or for which the numerical procedure imposes an abrupt strength drop at the onset of slip have h* = 0 and hence always fall into the inherently discrete class. We suggest that the small-event complexity that some such models show will not survive regularization of the constitutive description, by inclusion of an appropriate length scale leading to a finite h*, and a corresponding reduction of numerical grid size.