Collaborative Research: Integrating Petrochronology, Magma Dynamics, and Volcanic Unrest at the Three Sisters Volcanic Complex

火山喷发有可能在地方到全球范围内威胁农业、基础设施、航空和人类生命。这些事件代表了持续数千年到数百万年的地质过程和火山储集层的不稳定的交集，这种不稳定可能只在几天到几年内迅速发生。这些过程可以通过对过去喷发的回顾地质研究和地球物理监测来分别询问。该项目的重点是将这些方法整合到三姐妹火山综合体，这是一个位于美国西部的“具有极高威胁潜力”的火山系统。目标是通过对最近的喷发和火山骚乱的调查，阐明三姐妹所特有的危害，并提出新的概念和数量模型，可用于了解危害和改进全球活火山喷发预测。该项目的成果将通过在线发布的动画和视频向公众传播，并向三姐妹荒野地区的许多休闲游客提供自导地质学徒步旅行指南。将催化岩浆储集层生长、演化、不稳定和喷发的过程与它们表现为可观察到的动荡联系起来，这是一个重要的科学前沿，需要地学领域的跨学科合作。地球物理、岩石年代学和数值模拟方面的并行进展为理解岩浆成藏过程做出了实质性贡献。然而，这些方法仍然没有得到很好的整合。从玄武岩安山岩到流纹岩的成分从玄武岩安山岩到流纹岩的频繁喷发与现代火山动乱不同寻常地交汇在一起，使三姐妹成为研究这种综合方法的主要天然实验室。该项目将产生新的晶体规模的熔岩和相关爆炸产品的岩石年代学数据，这些数据来自俄勒冈州喀斯喀特中部的三姐妹火山复合体，在过去大约50,000年间喷发。这些数据将有助于解释：1)在三姐妹处喷发的流纹岩和英安岩熔岩的岩石成因以及这些岩石类型之间是否有成因联系；2)产生晚更新世中期火山和硅质火山爆发的岩浆储集层(S)的寿命和物理整合；3)在这些喷发之前并可能触发这些喷发的过程的性质和节奏。同时，将进行高分辨率布格重力测量，以约束现代岩浆储集层的物理结构。这些新的地球化学和地球物理数据将在岩浆动力学和地壳变形的耦合模型中与现有的近期隆起的大地测量相结合。因此，这些观察和模型将定量测试最近三姐妹的骚乱是否反映了与晚更新世火山有关的类似过程。这一裁决反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Volcanic eruptions have to potential to threaten agriculture, infrastructure, aviation, and human life at local to global scales. These events represent the intersection of geologic processes that proceed over thousands to millions of years and destabilization of the volcanic reservoir which may occur rapidly over only days to years. These processes may be interrogated through retrospective geologic studies of past eruptions and geophysical monitoring, respectively. This project is focused on integrating these approaches at the Three Sisters Volcanic Complex, a “very high threat potential” volcanic system located in the western United States. The goals are to elucidate hazards specific to the Three Sisters through the investigation of recent eruptions and volcanic unrest and produce new conceptual and quantitative models that can be applied to understand the hazards and improve eruption forecasting for active volcanoes globally. The results of this project will be disseminated to the general public through animation and videos published on-line and a self-guided geology hiking guide made available to the many recreational visitors to the Three Sister’s Wilderness Area.Linking the processes that catalyze the growth, evolution, destabilization, and eruption of magma reservoirs to their expression as observable unrest represents an important scientific frontier that requires inter-disciplinary collaborations across the geosciences. Parallel advances in geophysics, petrochronology, and numerical modeling have made substantial contributions to the understanding of magma reservoir processes. Yet, these methods remain poorly integrated. The unusual confluence of frequent late Pleistocene to late Holocene eruptions, which range in composition from basaltic andesite to rhyolite, with modern volcanic unrest make the Three Sisters a prime natural laboratory at which to pursue this integrated approach. This project will produce new crystal-scale petrochronologic data for lavas and associated explosive products erupted from the Three Sisters Volcanic Complex, central Oregon Cascades, during the last ca. 50,000 yr. These data will inform interpretations of: 1) the petrogenesis of the rhyolite and dacite lavas erupted at the Three Sisters and if there is a genetic relationship between these rock types; 2) the longevity and physical integration of the magma reservoir(s) that produced the late Pleistocene flare-up of intermediate and silicic volcanism; and 3) the nature and tempo of the processes that preceded, and potentially triggered, these eruptions. In parallel, a high-resolution Bouguer gravity survey will be conducted to constrain the physical structure of the modern magma reservoir. These new geochemical and geophysical data will be integrated with the existing geodetic observations of recent uplift in coupled models of magma dynamics and crustal deformation. Accordingly, these observations and models will quantitatively test if recent unrest at Three Sisters reflects similar processes to those associated with the late-Pleistocene volcanism.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.