Migrating shallow slow slip on the Nankai Trough megathrust captured by borehole observatories

• 成果类型: Article
• 署名作者: Edgington, Joshua R.; Saffer, Demian M.; Williams, Charles A.
• 署名单位: University of Texas System; University of Texas Austin; GNS Science - New Zealand
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-12781
• DOI: 10.1126/science.ads9715
• 发表日期: 2025-06-26
• 页码: 1396-1400
• 关键词: hikurangi subduction zone; sea-floor; earthquakes; events; plate; stress; models; trench; tremor; FAULT

摘要

Patterns of strain accumulation and release offshore in subduction zones are directly linked to the potential for shallow coseismic slip and tsunamigenesis, but these patterns remain elusive. In this work, we analyze formation pore pressure records from three offshore borehole observatories at the Nankai subduction zone, Honshu, Japan, to capture detailed slip-time histories of two slow slip events (SSEs) along the outermost reaches of the plate boundary. Slip initiates similar to 30 kilometers landward of the trench; migrates seaward at 1 to 2 kilometers per day to within a few kilometers of, and possibly breaching, the trench; and coincides with the onset and migration of tremor and/or very-low-frequency earthquakes. The SSE source region lies in a zone of high pore fluid pressure and low stress, which provides clear observational evidence linking these factors to shallow slow earthquakes.