We cluster a global database of 3529 Mw>5.5 earthquakes in 1995–2018 based on a dynamic time warping distance between earthquake source time functions (STFs). The clustering exhibits different degrees of complexity of the STF shapes and suggests an association between STF complexity and earthquake source parameters. Most of the thrust events have simple STF shapes across all depths. In contrast, earthquakes with complex STF shapes tend to be located at shallow depths in complicated tectonic regions, exhibit long source duration compared with others of similar magnitude, and tend to have strike‐slip mechanisms. With 2D dynamic modeling of dynamic ruptures on heterogeneous fault properties, we find a systematic variation of the simulated STF complexity with frictional properties. Comparison between the observed and synthetic clustering distributions provides useful constraints on frictional properties. In particular, the characteristic slip‐weakening distance could be constrained to be short (⁠<0.1 m⁠) and depth dependent if stress drop is in general constant.

中文翻译：

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震源时间函数聚类揭示地震动力学模式

我们基于地震源时间函数 (STF) 之间的动态时间扭曲距离，对 1995-2018 年 3529 Mw>5.5 地震的全球数据库进行了聚类。聚类表现出不同程度的 STF 形状的复杂性，并表明 STF 复杂性与震源参数之间存在关联。大多数推力事件在所有深度都有简单的 STF 形状。相比之下，具有复杂 STF 形状的地震往往位于复杂构造区域的浅层，与其他类似震级的地震相比，震源持续时间长，并且往往具有走滑机制。通过对异质断层特性的动态破裂进行二维动态建模，我们发现模拟 STF 复杂性与摩擦特性的系统变化。观察到的和合成的聚类分布之间的比较为摩擦特性提供了有用的约束。特别是，如果应力降通常是恒定的，那么特征滑动减弱距离可以被限制为较短（<0.1 m）并且取决于深度。