太平洋西北部地壳正在分段撕裂

科学家发现，位于太平洋西北部温哥华岛附近的卡斯卡迪亚俯冲带正在经历分段分裂过程1。这项由美国国家科学基金会资助的2021年卡斯卡迪亚地震成像实验（CASIE21）通过地震成像技术捕捉到了这一地质现象，研究成果已发表在《科学进展》2025年第11卷第39期1。

研究表明，在延伸约75公里的撕裂带中，部分区域已完全断裂，另有部分仍在产生地震1。板块在某处下沉了大约5公里，形成巨大的断层1。路易斯安那州立大学地质学家布兰登·舒克指出："与其一次性全部停止，板块是逐片撕裂，形成更小的微板块和新的边界"1。这一俯冲带分裂过程以百万年为单位展开，而非几十年或几个世纪1。

虽然发现了这种长期的地质变化，但研究人员强调这一过程在人类时间尺度上对该地区地震危害没有显著改变1。这项研究有助于解释古代板块碎片、火山活动以及未来地震行为1。

Scientists have captured evidence of the Cascadia Subduction Zone undergoing gradual fragmentation through seismic imaging techniques near Vancouver Island, according to research published in Science Advances 1. Rather than ceasing abruptly as a single massive system, the enormous subduction zone is deteriorating in segments, a process that researchers say unfolds over millions of years rather than decades or centuries 1.

The findings emerged from the 2021 Cascadia Earthquake Imaging Experiment (CASIE21), funded by the U.S. National Science Foundation 1. Within a rupture zone spanning approximately 75 kilometers, some regions have fractured completely while others continue generating seismic activity 1. In certain locations, the plate has subsided roughly 5 kilometers, creating substantial fault structures 1. As Brandon Shuck, a geologist at Louisiana State University, explained: "Instead of all stopping at once, the plates are tearing piece by piece, forming smaller microplates and new boundaries" 1.

The research provides new insights into ancient plate fragments, volcanic activity, and future earthquake behavior in the region 1. However, researchers emphasize that this fragmentation process, operating on geological timescales, has not significantly altered seismic hazards for the area in human terms 1.