近日，美国布朗大学的Victor C. Tsai及其研究团队取得一项新进展。经过不懈努力，他们发现断层网几何形状影响地震摩擦行为。相关研究成果已于2024年6月5日在国际权威学术期刊《自然》上发表。

该研究团队通过探索美国加利福尼亚州断层网络几何形状与地表蠕变率之间的关系，提出了断层蠕变的新见解。分析显示，具有蠕变行为的断层组在其网络几何结构上呈现出较小的错位。观测数据揭示，蠕变区的地表断层轨迹较为简单，而闭锁区的则趋于复杂。研究人员指出，复杂的断层网络几何结构导致了几何闭锁，从而促进了以地震为特征的粘滑行为；而简单的几何形状则有利于平滑的断层蠕变。

这一发现挑战了传统上仅基于断层摩擦来解释断层蠕变物理起源的假设，并展示了一个新的框架的潜力，在这个框架中，大规模地震的摩擦行为是由断层网络的几何因素与流变屈服特性共同决定的。

据悉，了解控制断层滑动稳定性的因素是断层力学中的一个关键问题。最近的实验室实验和数值模型强调了断层几何形状和粗糙度对断层滑动行为的重要性，并且新出现的证据表明，断层网络中的大规模复杂性在断层破裂过程中起着至关重要的作用。

附：英文原文

Title: Fault-network geometry influences earthquake frictional behaviour

Author: Lee, Jaeseok, Tsai, Victor C., Hirth, Greg, Chatterjee, Avigyan, Trugman, Daniel T.

Issue&Volume: 2024-06-05

Abstract: Understanding the factors governing the stability of fault slip is a crucial problem in fault mechanics. The importance of fault geometry and roughness on fault-slip behaviour has been highlighted in recent lab experiments and numerical models, and emerging evidence suggests that large-scale complexities in fault networks have a vital role in the fault-rupture process. Here we present a new perspective on fault creep by investigating the link between fault-network geometry and surface creep rates in California, USA. Our analysis reveals that fault groups exhibiting creeping behaviour show smaller misalignment in their fault-network geometry. The observation indicates that the surface fault traces of creeping regions tend to be simple, whereas locked regions tend to be more complex. We propose that the presence of complex fault-network geometries results in geometric locking that promotes stick-slip behaviour characterized by earthquakes, whereas simpler geometries facilitate smooth fault creep. Our findings challenge traditional hypotheses on the physical origins of fault creep explained primarily in terms of fault friction and demonstrate the potential for a new framework in which large-scale earthquake frictional behaviour is determined by a combination of geometric factors and rheological yielding properties.

DOI: 10.1038/s41586-024-07518-6

Source: https://www.nature.com/articles/s41586-024-07518-6