School of GeoSciences, University of Edinburgh, Edinburgh, UK.
Department of Geosciences, The Pennsylvania State University, State College, PA, USA.
Nat Commun. 2021 Mar 2;12(1):1397. doi: 10.1038/s41467-021-21596-4.
Recent large basaltic eruptions began after only minor surface uplift and seismicity, and resulted in caldera subsidence. In contrast, some eruptions at Galápagos Island volcanoes are preceded by prolonged, large amplitude uplift and elevated seismicity. These systems also display long-term intra-caldera uplift, or resurgence. However, a scarcity of observations has obscured the mechanisms underpinning such behaviour. Here we combine a unique multiparametric dataset to show how the 2018 eruption of Sierra Negra contributed to caldera resurgence. Magma supply to a shallow reservoir drove 6.5 m of pre-eruptive uplift and seismicity over thirteen years, including an Mw5.4 earthquake that triggered the eruption. Although co-eruptive magma withdrawal resulted in 8.5 m of subsidence, net uplift of the inner-caldera on a trapdoor fault resulted in 1.5 m of permanent resurgence. These observations reveal the importance of intra-caldera faulting in affecting resurgence, and the mechanisms of eruption in the absence of well-developed rift systems.
最近的大型玄武岩喷发发生在轻微的地表抬升和地震活动之后，导致火山口沉降。相比之下，加拉帕戈斯群岛火山的一些喷发则是在长时间、大幅度抬升和地震活动增加之前发生的。这些系统还显示出长期的火山口内抬升或复兴。然而，观测资料的缺乏掩盖了这种行为的机制。在这里，我们结合了一个独特的多参数数据集，展示了 2018 年塞拉内格拉火山喷发如何促成了火山口复兴。岩浆供应到一个浅层储层，在 13 年的时间里引发了 6.5 米的喷发前抬升和地震活动，包括触发喷发的 Mw5.4 地震。尽管共喷发期间的岩浆撤退导致了 8.5 米的沉降，但活门断层内火山口内的净抬升导致了 1.5 米的永久性复兴。这些观测结果揭示了火山口内断层在影响复兴方面的重要性，以及在没有发达裂谷系统的情况下喷发的机制。
