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

火山爆发有可能威胁当地乃至全球范围内的农业、基础设施、航空和人类生活。这些事件代表了持续数千年到数百万年的地质过程和可能在几天到几年内迅速发生的火山储层不稳定的交集。这些过程可以分别通过对过去喷发的回溯性地质研究和地球物理监测来询问。这个项目的重点是将这些方法整合到三姐妹火山复合体中，这是一个位于美国西部的“非常高威胁潜力”的火山系统。目标是通过对最近火山爆发和火山动荡的调查来阐明三姐妹火山特有的危害，并产生新的概念和定量模型，这些模型可以应用于了解危害并改进全球活火山的喷发预测。该项目的研究成果将以动画及影片的形式在网上公布，并向前往三姐妹荒野地区的众多休闲游客提供自助地质远足指南。将催化岩浆储层生长、演化、不稳定和喷发的过程与可观察到的不稳定状态联系起来，是一个重要的科学前沿，需要跨地球科学的跨学科合作。地球物理学、岩石年代学和数值模拟方面的平行进展为了解岩浆储层过程作出了重大贡献。然而，这些方法的整合仍然很差。频繁的晚更新世到晚全新世火山喷发，其组成范围从玄武岩安山岩到流纹岩，与现代火山动荡的不同寻常的融合，使三姐妹成为追求这种综合方法的主要自然实验室。该项目将为俄勒冈州中部喀斯喀特三姐妹火山群在过去约5万年中喷发的熔岩和相关爆炸产物提供新的晶体尺度岩石年代学数据。这些数据将有助于解释：1)三姐妹火山群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存在遗传关系；2)导致晚更新世中期和硅质火山活动爆发的岩浆储层的寿命和物理整合；3)在这些喷发之前和可能引发这些喷发的过程的性质和速度。同时，将进行高分辨率布格重力测量，以约束现代岩浆储层的物理结构。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耦合模型中与最近隆起的现有大地测量观测相结合。因此，这些观测和模型将定量地测试三姐妹最近的动荡是否反映了与晚更新世火山活动相关的类似过程。该奖项反映了美国国家科学基金会的法定使命，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。

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.