近日，美国加州理工学院Jean-Philippe Avouac团队报道2025年缅甸曼德勒Mw7.7地震揭示了实皆断裂带上具有聚集性和可变分段性的复杂地震周期。2025年8月11日，《美国科学院院刊》杂志发表了这一成果。

研究组以遥感观测为主题，记录了2025年曼德勒Mw7.7地震引起的地表变形。此次破裂具有约510千米的超长持续超剪切特性，其成因可能得益于结构成熟的实皆断裂带该段落异常光滑连续的几何形态。地震破裂涉及断层的整个深度范围（0 - 13 km）的锁定部分，滑动分布非常均匀，平均为3.3 m，平均应力降为4.7 MPa。未观察到浅滑亏损。断裂程度挑战了地震震级、断层长度和滑动的尺度规律。该断层沿着已知的地震间隙破裂，该地震间隙上一次破裂是在1839年，并在1930年和1946年的大地震中逐渐缩小为破裂的部分。

2025年事件中断层滑动的幅度和空间分布仅近似地符合滑动预测模型以及从断层几何形状和过去破裂推断的分割。采用简化的非平面断层几何模型，在准动力学模拟中产生了具有可变震级、分段和回归周期的可测地震序列，其中包括类似于2025年地震的事件。模拟结果与历史地震活动性、最大震级~Mw7.9和回归周期（~250 y）一致。将数据同化到这样的模拟中可以为将来的随时间变化的危害评估提供一种方法。

附：英文原文

Title: The 2025 Mw7.7 Mandalay, Myanmar, earthquake reveals a complex earthquake cycle with clustering and variable segmentation on the Sagaing Fault

Author: Antoine, Solene L., Shrestha, Rajani, Milliner, Chris, Im, Kyungjae, Rollins, Chris, Wang, Kang, Chen, Kejie, Avouac, Jean-Philippe

Issue&Volume: 2025-8-11

Abstract: We use remote sensing observations to document surface deformation caused by the 2025 Mw7.7 Mandalay earthquake. This event is a unique case of an extremely long (~510 km) and sustained supershear rupture probably favored by the rather smooth and continuous geometry of this section of the structurally mature Sagaing Fault. The seismic rupture involved the locked portion of the fault over its entire depth extent (0 to 13 km) with a remarkably uniform slip distribution that averages 3.3 m, and an average stress drop of 4.7 MPa. No shallow-slip deficit is observed. The rupture extent challenges usual scaling laws relating earthquake magnitude, fault length, and slip. The fault ruptured along a known seismic gap that last ruptured in 1839 and tailed off into sections that ruptured during large earthquakes in 1930 and 1946. The amplitude and spatial distribution of fault slip in the 2025 event conform only approximatively to the slip-predictable model and the segmentation inferred from the fault geometry and past ruptures. Plausible sequences of earthquakes with variable magnitude, segmentation, and return periods, including events similar to the 2025 earthquake are produced in quasidynamic simulations using a simplified but nonplanar fault geometry. Based on this simulation, Mw>7.5 events return irregularly with an interevent time of ~141 y on average and a SD of ~40 y. The simulation is consistent with the historical seismicity and with the maximum magnitude ~Mw7.9 and return period (~250 y) derived from moment conservation. Data assimilation into such simulations could provide a way for time-dependent hazard assessment in the future.

DOI: 10.1073/pnas.2514378122

Source: https://www.pnas.org/doi/abs/10.1073/pnas.2514378122