The Southern Patagonian Icefield (SPI) lies above an area of slow convergence between Antarctic and South-America plates, where limited seismicity is recorded by global and regional seismic networks. To understand the seismic behavior of this zone, we analyze two years of continuous broad-band data recorded by 27 seismometers, deployed around the SPI. Substantial ice loss coupled with the unusually low viscosity of the underlying mantle is causing a rapid uplift. Our findings indicate that most of the seismicity occurs in the upper crust likely associated with the (re)activation of regional compressive structures. However, earthquakes immediately beneath the SPI generally are shallower and show normal or strike-slip faulting. We suggest that this activity is promoted as a response to the crustal relaxation after rapid ice removal of SPI. The almost complete absence of interplate and intraslab events is consistent with a locked megathrust fault interface, highlighting the similarity of this region with the Cascadia subduction zone.

中文翻译：

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断层重新激活与南巴塔哥尼亚冰原（48-52°S）的冰块快速移除有关


南巴塔哥尼亚冰原 (SPI) 位于南极板块和南美洲板块缓慢汇聚的区域上方，全球和区域地震网络记录的地震活动有限。为了了解该区域的地震行为，我们分析了部署在 SPI 周围的 27 个地震仪记录的两年连续宽带数据。大量的冰损失加上底层地幔的异常低粘度正在导致快速隆起。我们的研究结果表明，大部分地震活动发生在上地壳，可能与区域压缩结构的（重新）激活有关。然而，紧邻 SPI 下方的地震通常较浅，并显示正断层或走滑断层。我们认为，这种活动的促进是对 SPI 快速除冰后地壳松弛的反应。几乎完全没有板间和板内事件，这与锁定的巨型逆冲断层界面一致，突出了该区域与卡斯卡迪亚俯冲带的相似性。