近日，中国地震局地质研究所范佳伟团队研究了青藏高原东南部小江断裂带2.5万年综合大地震记录——来自阳宗海的新古地震证据。这一研究成果于2025年12月23日发表在《中国科学：地球科学》杂志上。

小江断裂带（青藏高原的重要边界断裂系统）频繁发生大地震（面波震级Ms≥7.0），对社会安全构成严重威胁。然而，由于缺乏此类事件的长期连续记录，该区域地震活动行为的不确定性显著增加。基于探槽的古地震研究面临挑战，原因在于大地震往往表现为地下破裂、破坏断裂带上的变形特征，且断裂分支分布复杂。近期古地震研究表明，阳宗海内的事件沉积可能保存了小江断裂带历史上大地震的证据。

研究组基于岩性、颜色、结构、平均粒度、分选性、锰锆含量及碳氮比识别出的事件沉积物，并结合放射性碳测年，建立了该断裂带2.5万年以来连续的大地震记录。数据源自阳宗海沉积中心的两根沉积柱，辅以湖盆反射地震图像，完善了早先基于探槽的古地震记录。阳宗海记录的古地震事件（主要源自断裂带中段）呈现弱周期性复发特征，复发间隔介于333±3年至6320±651年之间，平均为1765±460年。

综合历史记载、探槽记录及湖相沉积的古地震序列表明，小江断裂带的全新世地震活动性有所增强，并在过去千年达到了前所未有的高频大地震活动期。这一地震活跃期恰与该区域人类活动显著增强的阶段相重合。这些发现突出表明，亟需对该区域的古地震活动性与地震危险性进行全面的重新评估。

附：英文原文

Title: A 25,000-yr-long integrated large earthquake record of the Xiaojiang Fault zone, southeastern Tibetan Plateau: New paleoseismic evidence from Yangzong Lake

Author: Jiawei FAN, Fangming ZHANG, Hanchao JIANG, Hongyan XU, Minggang CAI, Kai CUI, Dayou ZHAI, Changfei JIN, Kai LI, Wei SHI, Xiaotong WEI, Ning ZHONG, Yue BAI, Xingqi LIU, Jule XIAO

Issue&Volume: 2025/12/23

Abstract: The frequent occurrence of large earthquakes (surface wave magnitude, Ms≥7.0) along the Xiaojiang Fault zone (a key boundary fault system of the Tibetan Plateau) poses a serious threat to social security. However, the absence of long-term continuous records of such events increases the uncertainty surrounding the seismic behavior in this region. Paleoseismic investigations based on trenching are challenging due to subsurface rupturing during large earthquakes, destruction of on-fault deformation features, and the complex distribution of fault branches. Recent paleoseismic studies have suggested that event deposits in Yangzong Lake may preserve evidence of large historical earthquakes within the Xiaojiang Fault zone. Here, we present a 25,000-yr continuous record of large earthquakes in the fault zone, based on radiocarbon-dated event deposits identified by lithology, color, structure, mean grain size, sorting, Mn and Zr contents, and C/N ratio. These data are derived from two sediment cores from the depocenter of Yangzong Lake, supplemented by a reflection seismic image of the lake basin, and improve upon earlier trench-based paleoseismic records. The paleoseismic events recorded in Yangzong Lake (primarily originating from the middle segment of the fault) exhibit a weakly periodic recurrence pattern, with intervals ranging from 333±3 to 6320±651yr and averaging 1765±460yr. Integrated paleoseismic sequences from historical, trench-derived, and lacustrine records indicate an increase in seismicity along the Xiaojiang Fault zone during the Holocene, culminating in an unprecedented frequency of large earthquakes over the past millennium. This period of heightened seismic activity coincides with a notable intensification of human presence in the region. These findings highlight the urgent need for a comprehensive reassessment of paleoseismicity and seismic hazard in the area.

DOI: 10.1007/s11430-025-1772-1

Source: https://www.sciengine.com/SCES/doi/10.1007/s11430-025-1772-1