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)和英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。该协定允许美国和英国提交一个单一的联合提案，并由该机构进行同行审查，该机构的调查员在预算中所占比例最大。在成功地联合确定一个奖项后，每个机构将为预算和调查人员的比例提供资金，这些调查人员与其自己的调查人员和工作部分有关。火山喷口是地球上最令人敬畏的地质特征之一。火山口最常见的形成方式是岩浆沿裂谷地带喷发和/或侵入，以及上覆地壳的坍塌。2018年夏威夷基拉韦厄火山喷发就是一个很好的例子。然而，在某些情况下，火山口是通过复苏而生长的。加拉帕戈斯群岛的塞拉·内格拉火山是一座大型玄武岩火山口，在最近两次喷发期间通过重新喷发而生长。这项研究将把新的和现有的全球定位系统(GPS)精确定位数据与地震数据结合起来，以研究火山爆发前、同时和之后的过程。这将提高我们对导致火山口变形的岩浆和火山过程以及可能引发火山喷发的过程的理解。不仅在加拉帕戈斯，而且在全球的破火山口系统，例如夏威夷的基拉韦厄火山，了解这些过程对于火山危险评估都很重要。该项目将培训下一代火山地球物理学家，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NERC的伙伴关系，这个项目就不可能实现，NERC为塞拉利昂内格拉火山地震台网的发展和数据分析提供了资金。位于厄瓜多尔加拉帕戈斯群岛的塞拉内格拉火山是地球上最大的玄武岩火山口之一，面积为9公里乘7公里。通过NSF快速和NERC紧急项目的投资，2018年6月26日至8月30日内格拉山脉的喷发是当地地球物理监测网记录的加拉帕戈斯群岛火山的第一次喷发。由此产生的数据是惊人的。这次喷发包括6.5米的喷发前膨胀，在北侧形成了一个大约12公里长的裂隙系统，大约8.5米的共同喷发的通货紧缩(在火山口边界的环断层上观察到的最大的共同喷发位移之一)，和大约1.5米的净抬升(重新抬升)在火山口内陷门断裂系统上。数十万次地震伴随着喷发前和共同喷发阶段，包括高达5.4兆瓦的通货膨胀和通货紧缩的火山口内“活门”断层事件。NSFGEO-NERC合作计划非常适合将独特的、互补的大地测量和地震观测以及复杂的数值模拟技术结合在一起，以解决与内格拉山脉的行为、加拉帕戈斯火山活动的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的相互作用的重要悬而未决的问题。来自内格拉山脉的异常新的大地测量和地震观测为研究不同动乱阶段岩浆系统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到足够长的时间，以观察到从喷发前的膨胀、岩浆迁移和喷发开始，到共同喷发的通货紧缩，再到通胀的回归，一个完整的喷发序列。通过建模，将观测与火山系统内压力和应力的变化联系起来，我们将能够探索控制岩浆积累和退出以及火山喷发活动启动的岩浆和构造过程。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.