Gualandi A, Avouac J-P, Michel S, Faranda D
California Institute of Technology, Pasadena, CA, USA.
Laboratoire de Géologie, Département de Géosciences, École Normale Supérieure, PSL University, UMR CNRS 8538, Paris, France.
Sci Adv. 2020 Jul 1;6(27). doi: 10.1126/sciadv.aaz5548. Print 2020 Jul.
Slow earthquakes, like regular earthquakes, result from unstable frictional slip. They produce little slip and can therefore repeat frequently. We assess their predictability using the slip history of the Cascadia subduction between 2007 and 2017, during which slow earthquakes have repeatedly ruptured multiple segments. We characterize the system dynamics using embedding theory and extreme value theory. The analysis reveals a low-dimensional (<5) nonlinear chaotic system rather than a stochastic system. We calculate properties of the underlying attractor like its correlation and instantaneous dimension, instantaneous persistence, and metric entropy. We infer that the system has a predictability horizon of the order of days weeks. For the better resolved segments, the onset of large slip events can be correctly forecasted by high values of the instantaneous dimension. Longer-term deterministic prediction seems intrinsically impossible. Regular earthquakes might similarly be predictable but with a limited predictable horizon of the order of their durations.
慢地震与普通地震一样，是由不稳定的摩擦滑动引起的。它们产生的滑动很小，因此可以频繁重复。我们利用2007年至2017年卡斯卡迪亚俯冲带的滑动历史来评估它们的可预测性，在此期间，慢地震多次反复破裂多个区域。我们使用嵌入理论和极值理论来描述系统动力学。分析表明这是一个低维（<5）非线性混沌系统，而非随机系统。我们计算了潜在吸引子的相关性质，如它的关联维数和瞬时维数、瞬时持续性和度量熵。我们推断该系统的可预测范围约为几天到几周。对于分辨率更高的区域，通过瞬时维数的高值可以正确预测大滑动事件的发生。长期确定性预测似乎本质上是不可能的。普通地震可能同样具有可预测性，但可预测范围有限，约为其持续时间的量级。
