EAR-PF: Short fuses: investigating recent phreatic eruptions at Whakaari, New Zealand, through poroelastic modeling

EAR-PF：短熔丝：通过多孔弹性模型调查新西兰法卡里最近的潜水喷发

• 批准号: 2204527
• 负责人: John Albright
• 金额: $ 18万
• 依托单位: Albright, John A
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-05-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2204527&HistoricalAwards=false
• 关键词: EAR; PF; Short; fuses; investigating

Despite many recent advances in volcano monitoring, unforeseen volcanic eruptions pose a major hazard to human life and property around the world. Beyond the direct threat to the volcano’s immediate surroundings, ash clouds from such events can have far-reaching consequences, contaminating water supplies and rendering large sections of airspace unusable to commercial or defense traffic. Moreover, even foreign volcanoes can endanger American lives, given their popularity as tourist destinations. For example, the December 2019 eruption of Whakaari (White Island) in New Zealand left 5 American citizens dead and wounded 4 others. As with many deadly eruptions in recent history, this event was “phreatic”, driven primarily by the explosive release of shallow superheated steam rather than by the direct action of deeper magma. Such eruptions tend to occur suddenly; in many cases local monitoring networks do not observe any clear or reliable indication that an explosion is imminent. In these scenarios, local authorities are unable to evacuate the area, leading to significant casualties even from relatively small eruptions. Using Whakaari as a case study, this project will combine sophisticated computer simulations with years of monitoring data, spanning 3 eruptions, to investigate the volcano’s longer-term evolution. In particular, it seeks to study how non-eruptive activity at Whakaari may have predisposed or primed the system for the observed explosions. Ultimately, this process will deepen the scientific understanding of phreatic eruptions in general, beyond just Whakaari, and will allow these volatile events to be forecasted more reliably, even in the absence of immediate warning signs.The first stage of this project will synthesize previous advances in numerical modeling to develop a finite element simulation capable of fully capturing the poroelastic interactions between a volcano’s shallow hydrothermal system, from which phreatic eruptions are most often triggered, and the surrounding host rock. By combining the physics of fluid flow with those of rock deformation, this model will be able to predict how the volcano would mechanically respond to different configurations of permeability and magma influx. The second phase of the study would then use statistical data assimilation techniques to compare these predictions against measurements of ground deformation at Whakaari, finding the sets of underlying conditions that best match the volcano’s observed behavior. These models can then be further constrained and validated by comparing their predictions against additional seismic and geochemical observations. In the end, this project aims to test the hypothesis that Whakaari’s eruptions were caused by the mechanical rupture of low-permeability hydrothermal seals which had caused the slow accumulation of pressure in the months to years beforehand. Additionally, it will determine whether the modeled stress state of the system would have been sufficient to cause seal failure alone, or if an additional external trigger was required. By considering phreatic eruptions in the context of a volcanic system’s longer-term mechanical evolution, this study will help to understand how there events are triggered, what precursory activity may occur beforehand, and why certain precursors may be present for some eruptions but not others.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.

尽管最近在火山监测方面取得了许多进展，但不可预见的火山喷发除了对火山周围环境造成直接威胁外，还对世界各地的人类生命和财产构成重大危害，此类事件产生的火山灰云可能会产生深远的后果，污染水源和水源。此外，鉴于它们作为旅游目的地的受欢迎程度，即使是外国火山也可能危及美国人的生命。新西兰的法卡里火山（怀特岛）导致 5 名美国公民死亡，另有 4 人受伤，与近代历史上许多致命的火山喷发一样，这次事件是“潜水式”的，主要是由浅层过热蒸汽的爆炸性释放驱动的，而不是直接作用。此类喷发往往是突然发生的；在许多情况下，当地监测网络没有观察到任何明确或可靠的迹象表明即将发生爆炸，当地政府无法撤离该地区，甚至会导致重大人员伤亡。该项目以相对较小的火山喷发为案例研究，将复杂的计算机模拟与跨越 3 次喷发的多年监测数据相结合，以研究火山的长期演变，特别是研究非喷发活动的情况。法卡里可能已经为观察到的爆炸预先准备或准备好了系统，最终，这个过程将加深对法卡里之外的一般潜水喷发的科学理解，并将允许这些不稳定的事件发生。即使在没有立即警告信号的情况下，预测也更加可靠。该数值项目的第一阶段将综合以前的建模进展，开发有限元模拟，能够完全捕获火山浅层热液系统之间的孔隙弹性相互作用，从该浅层热液系统中喷发通过将流体流动的物理原理与岩石变形的物理原理相结合，该模型将能够预测火山对不同渗透率和岩浆配置的机械响应。然后，研究的第二阶段将使用统计数据同化技术将这些预测与法卡里地面变形的测量结果进行比较，找到最符合火山观测行为的基本条件集，然后可以进一步限制和验证这些模型。通过将他们的预测与额外的地震和地球化学观测结果进行比较，该项目的目的是检验法卡里火山喷发是由低渗透性热液的机械破裂引起的假设。此外，还将确定系统的模拟应力状态是否足以单独导致密封失效，或者是否需要额外的外部触发。在火山系统长期机械演化的背景下进行潜水喷发，这项研究将有助于了解事件是如何触发的，事先可能发生什么前兆活动，以及为什么某些喷发可能出现某些前兆，而其他喷发则不会。该奖项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，NSF 的法定使命被认为值得支持。