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，但不可预见的火山爆发对世界各地的人类生命和财产构成重大危险。除了对火山周围环境的直接威胁外，这些事件产生的火山灰云可能会产生深远的影响，污染水源，并使大片空域无法用于商业或国防交通。此外，即使是外国的火山也可能危及美国人的生命，因为它们是受欢迎的旅游目的地。例如，2019年12月新西兰Whakaari（白色岛）火山爆发造成5名美国公民死亡，4人受伤。与近代历史上许多致命的喷发一样，这次事件是“潜水”事件，主要是由浅层过热蒸汽的爆炸性释放而不是更深处岩浆的直接作用驱动的。这种喷发往往突然发生;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。在这些情况下，地方当局无法撤离该地区，导致即使是相对较小的爆发也会造成重大伤亡。该项目将以Whakaari为案例研究，将联合收割机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，以调查火山的长期演变。特别是，它试图研究Whakaari的非喷发活动如何可能使该系统发生所观察到的爆炸。最终，这一过程将加深对潜水喷发的科学理解，而不仅仅是瓦卡瑞，并将使这些不稳定的事件能够更可靠地预测，该项目的第一阶段将综合以前在数值模拟方面的进展，开发一种有限元模拟方法，能够充分捕捉火山浅层热液之间的孔隙弹性相互作用，系统，其中潜水喷发是最经常触发，和周围的主机岩石。通过将流体流动的物理学与岩石变形的物理学相结合，该模型将能够预测火山将如何对渗透性和岩浆流入的不同配置作出机械响应。研究的第二阶段将使用统计数据同化技术将这些预测与Whakaari的地面变形测量进行比较，找到最符合火山观测行为的基础条件。然后，通过将这些模型的预测与额外的地震和地球化学观测进行比较，可以进一步约束和验证这些模型。最后，该项目旨在测试Whakaari火山爆发是由低渗透性热液密封的机械破裂引起的假设，这种机械破裂导致了数月至数年前压力的缓慢积累。此外，还将确定系统的建模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。通过在火山系统长期机械演化的背景下考虑潜水喷发，这项研究将有助于了解事件是如何触发的，事先可能发生什么样的火山活动，以及为什么某些前兆可能出现在某些喷发中，而其他喷发则没有。该奖项反映了NSF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进行评估，被认为值得支持审查标准。