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Seismotectonic implications of the South Chile ridge subduction beneath the Patagonian Andes
Terra Nova ( IF 2.2 ) Pub Date : 2021-02-14 , DOI: 10.1111/ter.12521
Rodrigo Suárez 1 , Christian Sue 2, 3 , Matías Ghiglione 1 , Benjamin Guillaume 4 , Miguel Ramos 1 , Joseph Martinod 2 , Vanesa Barberón 1
Affiliation  

The South Chile ridge (SCR) intersects the Patagonian trench around 46°09′S, forming the triple junction among the Antarctic, Nazca, and South America plates. Subduction of the SCR since ~18 Ma produced the opening of a slab window beneath Patagonia and a noticeable magmatic gap in the cordillera, profuse volcanism and topographic uplift in the retroarc. To study seismicity distribution and present-day stress resulting from this particular framework, we analyse databases of seismic events and earthquake focal mechanisms. Our study finds that clusters of intraplate crustal seismic events are disrupted by a ~450–470 km seismicity gap above the slab window. Calculated stress tensors depict a strike-slip tectonic regime north of the triple junction, and ~W-E compression to the south of the seismic gap. We propose that the seismotectonic behaviour of the upper plate is disturbed at the first order by the trench-ridge intersection, leading to a heterogeneous stress field.

中文翻译:

巴塔哥尼亚安第斯山脉下智利南脊俯冲的地震构造意义

南智利海脊 (SCR) 在 46°09'S 附近与巴塔哥尼亚海沟相交,形成南极、纳斯卡和南美洲板块之间的三重连接。大约 18 Ma 以来 SCR 的俯冲在巴塔哥尼亚下方产生了一个板状窗口,并且在山脉中出现了明显的岩浆间隙,在弧后有大量的火山活动和地形隆起。为了研究由这个特定框架产生的地震活动分布和当前应力,我们分析了地震事件和地震震源机制的数据库。我们的研究发现,板内地壳地震事件的集群被板窗上方约 450-470 公里的地震活动间隙破坏。计算出的应力张量描绘了三重交界以北的走滑构造体系,以及地震间隙以南的~WE压缩​​。
更新日期:2021-02-14
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