The seismic cycle in subduction zones: quantification of deformation rates and strain partitioning in the 1960 Chile earthquake segment

俯冲带的地震周期：1960 年智利地震段变形率和应变划分的量化

• 批准号: 76859320
• 负责人: Professor Dr. Daniel Melnick
• 金额: --
• 依托单位: Instituto de Ciencias de la Tierra
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/76859320?language=en
• 关键词: seismic; cycle; subduction; zones; quantification

Subduction zones have generated the largest earthquakes on Earth; there, it has been thought that the longer the time since the last earthquake, the larger the next earthquake s slip, and consequently magnitude will be. However, historical and paleoseismic data has shown variable recurrence times and magnitude of large subduction earthquakes, which not necessarily follow this logical predictor. Gaining insight into this poorly understood problem is of utmost importance. All historical events that exceeded moment magnitude (Mw) 9 occurred in subduction zones where plate convergence is oblique. However, seismic and geodetic data show that coseismic slip occurred nearly normal to the megathrust s strike, implying that oblique convergence is somehow partitioned across the margin. The role of strain partitioning in the seismic cycle and the mechanism as to how transient variations in the degree of partitioning could modulate recurrence times and magnitudes of great subduction earthquakes, has not been fully explored. The Valdivia earthquake segment in south-central Chile, which in 1960 generated the largest, instrumentally recorded earthquake with Mw 9.5, is a suitable testing ground to study the seismic cycle and strain partitioning processes. This project attempts gaining insight into this problematic by determining: (1) deformation rates over the seismic cycle in the southern sector of the Valdivia segment; (2) deciphering the recurrence interval of large subduction earthquakes; and (3) characterizing the strainpartitioning budget over the seismic cycle. These objectives are best achieved through combined geomorphic and structural mapping, isotopic dating of deformed Quaternary landforms in the foreand intra-arc regions, measuring present-day deformation rates using continuous and campaign GPS, and by integrative tectonic modeling.

俯冲带产生了地球上最大的地震。在那里，人们认为，自上次地震以来的时间越长，下一个地震S滑移就越大，因此幅度将会越多。然而，历史和古呼吸数据显示了大俯冲地震的可变复发时间和大小，这不一定遵循这种逻辑预测指标。深入了解这个知之甚少的问题至关重要。所有超过力矩幅度（MW）9的历史事件均出现在板收敛是倾斜的俯冲带中。然而，地震和大地的数据表明，coseis震滑几乎与大型震荡的罢工一样正常，这意味着倾斜的收敛在整个边缘都分配了。应变分配在地震循环中的作用以及关于分区程度的瞬时变化如何调节复发时间和巨大俯冲地震的大小的作用。智利中南部智利的瓦尔迪维亚地震片段，该节目在1960年产生了用MW 9.5的最大的工具记录的地震，是研究地震循环和应变分配过程的合适测试地面。该项目试图通过确定：（1）Valdivia段南部地区地震周期的变形率来了解这一问题；（1）变形率； （2）破译大型俯冲地震的复发间隔； （3）表征在地震周期内的应变分区预算。最好通过结合的地貌和结构映射，在前季内部区域中变形季型地形的同位素约会，使用连续和竞选GPS测量当今的变形率，以及通过综合构造构造模型来测量当今的变形率。