近日，法国布雷斯特大学Lenhof, Edgar团队报道了原位地震大地测量所捕捉的海底扩张事件解析。这一研究成果发表在2026年7月8日出版的《自然》杂志上。

在地质时间尺度上，洋底的增长涉及洋中脊（MOR）处的岩浆和构造伸展。由于对这些海底板块边界的地震大地测量监测仍具有挑战性，人们对这些系统在年际尺度上的运行方式知之甚少。

研究组报道了据他们所知首次对洋中脊段裂谷事件的原位观测，该观测结合了水声学、直达路径测距和海底压力测量，并辅以重复海底测绘。该事件始于2024年4月26日，发生于南纬37°附近的东南印度洋脊（SEIR）轴部，距离跨洋脊轴和邻近阿姆斯特丹转换断层（TF）布设的仪器约两个月。该事件以沿轴向谷快速迁移的伸展性地震群开始，导致谷底沉降4米，跨谷水平伸展超过1米。

研究组将其解释为一个岩席状岩浆房沿洋脊轴供给传播的岩墙群时发生的放气作用。这些岩墙最终导致约1.6亿立方米的熔岩在约16天内喷出至海底，同时引发了谷边界正断层上的地震和非地震滑动，并最终触发了相邻转换断层上的地震活动。因此，由岩浆过程诱发的大规模非地震滑动可能是洋中脊正断层累积位移的主要机制，这也解释了这些断层长期以来的地震亏缺现象。

附：英文原文

Title: Anatomy of a seafloor spreading event captured by in situ seismogeodesy

Author: Royer, Jean-Yves, Olive, Jean-Arthur, Bazin, Sara, Ballu, Valrie, Briais, Anne, Retailleau, Lise, Raumer, Pierre-Yves, Lenhof, Edgar

Issue&Volume: 2026-07-08

Abstract: Over geological time, the growth of the ocean floor involves magmatic and tectonic extension1 at mid-ocean ridges (MORs). Because seismogeodetic monitoring of these submarine plate boundaries remains challenging2,3,4,5,6,7, little is known about how these systems operate on yearly timescales. Here we report the first, to our knowledge, in situ observation of a rifting event at a MOR segment that combines hydroacoustic, direct-path ranging and bottom-pressure measurements, with repeated seafloor mapping. This event started on 26 April 2024 at the axis of the Southeast Indian Ridge (SEIR) near 37°S, two months after instruments had been deployed across the ridge axis and nearby Amsterdam transform fault (TF). The event began as a rapidly migrating swarm of extensional seismicity along the axial valley. It caused 4m of subsidence of the valley floor and more than a metre of horizontal extension across the valley. We interpret this as the deflation of a sill-like reservoir feeding propagating dykes along the ridge axis. The dykes eventually led to the outpouring of about 160millionm3 of lava at the seafloor in about 16days, while inducing both seismic and aseismic slip on valley-bounding normal faults and finally triggering seismic activity on the abutting TFs. Large-scale aseismic slip induced by magmatic processes could therefore be the primary mechanism by which MOR normal faults accrue their displacement, which would account for their well-documented seismic deficit8,9.

DOI: 10.1038/s41586-026-10785-0

Source: https://www.nature.com/articles/s41586-026-10785-0

期刊信息

Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504

官方网址：http://www.nature.com/

投稿链接：http://www.nature.com/authors/submit_manuscript.html