Collaborative Research: NSFGEO-NERC: Mechanisms of deformation through a complete eruption cycle of Sierra Negra volcano, Galapagos Islands

这是一个由国家科学基金会地球科学理事会（NSF/GEO）和联合王国国家环境研究理事会（UKRI/NERC）通过NSF/GEO-NERC牵头机构协议共同资助的项目。该协议允许美国/英国提交一份联合提案，并由研究者拥有最大预算比例的机构进行同行评审。一旦成功地共同确定了一项奖励，每个机构就为预算的一部分和与自己的调查人员和工作组成部分有关的调查人员提供资金。火山口是地球上最令人敬畏的地质特征之一。火山口通常是通过岩浆的喷发和/或沿沿着裂谷带的侵入以及上覆地壳的坍塌而形成的。2018年夏威夷的基拉韦厄火山爆发就是一个很好的例子。然而，在某些情况下，破火山口通过复苏而增长。塞拉内格拉火山在加拉帕戈斯群岛，是一个大的玄武岩破火山口，已通过复苏增长在其最后两次爆发。这项研究将把新的和现有的全球定位系统精确定位数据与地震数据结合起来，调查喷发前、喷发时和喷发后的过程。这将提高我们对导致破火山口变形的岩浆和火山过程以及可能引发火山爆发的过程的理解。了解这些过程不仅对加拉帕戈斯的火山灾害评估很重要，而且对全球的破火山口系统（例如夏威夷的基拉韦厄火山）也很重要。该项目将培训下一代火山喷发学家，并继续美国，英国和厄瓜多尔科学家之间的长期合作。如果没有与NERC的合作，这个项目就不可能实现。NERC资助了Sierra Negra火山地震网络的开发和数据分析。Sierra Negra火山位于厄瓜多尔加拉帕戈斯群岛，是地球上最大的玄武岩火山口之一，长9公里，宽7公里。通过NSF RAPID和NERC紧急计划的投资，2018年6月26日至8月30日的Sierra Negra火山喷发是加拉帕戈斯群岛火山首次喷发，由当地地球物理监测网络记录。由此产生的数据是惊人的。喷发涉及6.5米的喷发前膨胀，形成了一个约12公里长的裂缝系统的北侧，约8.5米的共同喷发紧缩（有史以来最大的共同喷发位移没有崩溃的破火山口边界环断层），和约1.5米的净隆起（复活）的破火山口内活板门断层系统。数十万次地震伴随着前和共同喷发阶段，包括通货膨胀和通货紧缩火山口内的“活板门”断层事件高达Mw5.4。NSFGEO-NERC合作计划非常适合汇集独特的，互补的大地测量和地震观测以及复杂的数值模拟技术，以解决与Sierra Negra行为，加拉帕戈斯火山活动性质有关的具体问题，以及有关基本火山变形和火山建筑物与岩浆管道系统之间相互作用的重要悬而未决的问题。从Sierra Negra进行的特殊的新大地测量和地震观测为研究岩浆系统在不同动荡阶段的外部和内部变形提供了一个独特的机会。很少有火山系统被监测得足够好，足够长，可以观察到一个完整的喷发序列，从喷发前的膨胀，岩浆迁移和喷发开始，到共同喷发的紧缩，再到膨胀的回归。通过建模将观测结果与火山系统内的压力和应力变化联系起来，我们将能够探测控制岩浆积聚和撤退以及喷发活动开始的岩浆和结构过程。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This is a project that is jointly funded by the National Science Foundation’s Directorate of Geosciences (NSF/GEO) and the National Environment Research Council (UKRI/NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget. Upon successful joint determination of an award, each Agency funds the proportion of the budget and the investigators associated with its own investigators and component of the work.Volcanic calderas are some of the most awe-inspiring geologic features on earth. Calderas most often form through the withdrawal of magma through eruption and/or intrusion along rift zones, and collapse of the overlying crust. The 2018 eruption of Kilauea volcano, Hawaii was an excellent example of this. In some cases, however, calderas grow through resurgence. Sierra Negra volcano in the Galapagos Islands, is a large basaltic caldera that has grown through resurgence during its last two eruptions. This study will integrate new and existing Global Positioning System (GPS) precise positioning data with seismic data to investigate pre-, co- and post-eruptive processes. This will improve our understanding of the magmatic and volcanic processes that lead to caldera deformation and the processes that potentially trigger volcanic eruptions. Understanding these processes is important for volcanic hazard assessments not only in the Galapagos, but at caldera systems globally, for example, Kilauea volcano, Hawaii. This project will train the next generation of volcano geophysicists, and continue long-standing collaborations between US, UK, and Ecuadorian scientists. This project would not be possible without the partnership with NERC, who has funded the development of the seismic network and data analyses at Sierra Negra volcano.Sierra Negra volcano, in the Galápagos Islands of Ecuador, is one of the largest basaltic calderas on Earth, measuring 9 km by 7 km. Through investments from the NSF RAPID and NERC Urgency programs, the June 26-August 30, 2018 eruption of Sierra Negra was the first eruption at a Galápagos Islands volcano to be recorded by a local geophysical monitoring network. The resulting data are spectacular. The eruption involved 6.5 m of pre-eruptive inflation, formation of a ~12 km long fissure system on the north flank, ~8.5 m of co-eruptive deflation (one of the largest co-eruptive displacements ever observed without collapse on caldera-bounding ring faults), and ~1.5 m of net uplift (resurgence) on the intra-caldera trapdoor fault system. Hundreds of thousands of earthquakes accompanied the pre- and co-eruptive phases, including inflationary and deflationary intra-caldera ‘trapdoor’ faulting events up to Mw5.4. The NSFGEO-NERC collaborative scheme is ideally suited to bring together unique, complementary geodetic and seismic observations and sophisticated numerical modeling techniques to address specific questions relating to the behavior of Sierra Negra, the nature of Galápagos volcanism, and important outstanding questions about fundamental volcano deformation and the interaction between a volcanic edifice and magma plumbing system. The exceptional new geodetic and seismic observations from Sierra Negra offer a unique opportunity to investigate the external and internal deformation of a magmatic system at different stages of unrest. It is rare that a volcanic system is monitored well- and long-enough to observe a complete eruptive sequence from pre-eruptive inflation, magma migration and eruption onset, to co-eruptive deflation, and a return to inflation. By linking observations, through modeling, to changes in pressure and stress within the volcanic system, we will be able to probe the magmatic and structural processes that control magma accumulation and withdrawal, and the initiation of eruptive activity.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.