NSF GEO-NERC: Collaborative Proposal: A general model for bubble nucleation and growth in volcanic systems

该项目将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。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。在成功联合确定授标后，每个机构为与本机构调查员和工作组成部分有关的预算和调查员提供资金。气泡的成核和增长驱动了火山爆发。因此，如果我们要预测喷发风格以及喷发产物的性质，这些过程的定量建模是必不可少的。该项目将为火山研究界提供一个有用的工具，使我们的集体科学能够更好地理解并最终预测爆炸性喷发的性质、爆炸性和潜在危险。这种最严重的火山灾害来自于大规模的火山灰喷发。火山灰对火山周围的地区构成了当地的危害，如Mt. 1980年，圣海伦斯火山爆发，火山灰沉降物还威胁到更广泛的地区，可能污染地表水和农业土壤，导致呼吸压力，如果发生大规模喷发，还可能暂时改变全球气候。因此，这些喷发威胁着国家和全球安全，更全面地了解它们是科学的优先事项。为了达到这种理解的目标，这个项目的目标是到达火山的核心-气泡的成核，形成，成长和驱动爆炸性喷发。该项目包括国际和国内的合作与跨大学的指导学生和博士后，包括K-12推广和培训的本科生和研究生。该项目将创建和验证一个统一的数值模型的成核和增长的气泡在岩浆中，在最常见的组合物范围内与爆炸性喷发。目前，严格的定量理解的物理控制的成核和气泡的生长受到阻碍的两个知识差距有关的成核过程和复杂的，不断变化的气泡生长。该项目将联合收割机与理论建模相结合，通过以下方式克服这些知识差距：1）进行有针对性的实验，以约束一种新颖的、有理论基础的公式，该公式可以捕获均质和非均质成核; 2）创建一个气泡生长的数值模型，该模型可以捕获相互作用的气泡群的整体行为，其中成核位点的分布可能在时间和空间上演变; 3）将成核公式与气泡生长模型相结合，建立统一的模型。该整体气泡生长模型将使用成核公式来随机化并迭代地分配3D熔体体积内的成核事件，并使用壳模型的队列来跟踪所得气泡的生长。这个组合的数值模型将允许用户确定自然喷发路径的岩浆属性的演变，并为从喷发产物反演到推断管道内喷发条件奠定基础。该奖项反映了NSF的法定使命，并被认为值得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来支持。

This project will be 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. The nucleation and growth of bubbles drives explosive volcanic eruptions. As such, quantitative modelling of these processes is essential if we are to predict eruptive style, as well as the nature of eruptive products. This project will produce a useful tool for the volcanological research community and enable our collective science to better understand and ultimately predict the nature, explosivity, and potential hazard of explosive eruptions. This most serious volcanic hazard arises from large ash eruptions. Ash poses local hazards to the region surrounding volcanoes, such as Mt. St. Helens, in 1980, and also threatens a much broader area with ash fallout that can contaminate surface water and agricultural soils, lead to respiratory stress, and in the case of very large eruptions, can temporarily alter global climate. As such, these eruptions threaten national and global security, and understanding them more fully is a science priority. Toward the goal of such understanding, this project aims to get to the heart of volcanoes- the nucleation of bubble that form, grow and drive explosive eruptions. The project includes international and domestic collaborations with cross-university mentoring of students and postdocs, including K-12 outreach and training of undergraduate and graduate students.This project will create and validate a unified numerical model for the nucleation and growth of bubbles in magma, across the range of compositions most commonly associated with explosive eruptions. At present, rigorous quantitative understanding of the physical controls on the nucleation and growth of bubbles is impeded by two knowledge gaps relating to nucleation processes and complex, evolving bubble growth. The project will combine novel experiments with theoretical modeling to overcome these knowledge gaps by 1) Conducting targeted experiments to constrain a novel, theoretically-grounded formulation that captures both homogeneous and heterogeneous nucleation; 2) Creating a numerical model of bubble growth that captures the ensemble behavior of cohorts of interacting bubbles, in which the distribution of nucleation sites may evolve in time and space; 3) Combining the nucleation formulation and bubble growth model to create a unified model. That ensemble bubble growth model will use the nucleation formulation to stochastically and iteratively assign nucleation events within a 3D volume of melt, and track the growth of the resulting bubbles using cohorts of shell models. This combined numerical model will allow users to determine the evolution of magma properties for natural eruption pathways, and set the stage for inverting from eruptive products to infer in-conduit eruptive conditions.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.