Collaborative Research: ELUCIDATING CONDUIT, ERUPTION AND PYROCLAST TRANSPORT DYNAMICS OF LARGE SILICIC SUBMARINE ERUPTIONS

合作研究：阐明大型硅质海底喷发的管道、喷发和火山碎屑输送动力学

• 批准号: 1357443
• 负责人: Bruce Houghton
• 金额: $ 45.49万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-12-01 至 2019-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1357443&HistoricalAwards=false
• 关键词: Collaborative; Research; ELUCIDATING; CONDUIT; ERUPTION

There are tens of thousands of volcanoes on the ocean floor. It is not known how many of these are erupting at any given time because most are overlain by many hundreds to thousands of feet of water that prevent the escape of eruption products into the atmosphere or onto the sea surface where they can be spotted by ships, airplanes, or satellites. Similarly, it is not known how many of these undersea volcanoes erupt explosively, generating large quantities of ash and pumice that is then distributed by currents or cause volcanic slope instabilities that can result in tsunamis. Because seafloor eruptions, in particular those that are explosive in nature, are hidden from view, our knowledge of how they operate, their eruption products and their distribution, and their geohazard potential is almost unknown. Luckily in July 2012, a 200 square kilometer raft of pumice was spotted floating on the ocean in the western Pacific just above Havre Volcano which is under 1600 meters of water, indicating a major explosive eruption. Taking advantage of this event, this project mounts a major scientific investigation of the eruption. The research involves a comprehensive physical and chemical study of the volcano, the eruption, and the associated eruption products and their distribution near and far from their point of origin. Through an oceanographic cruise using state-of-the-art robotic vehicles, the investigators will collect samples and sediment cores and create seafloor photo mosaics of the area. The research also involves high resolution seafloor mapping and stratigraphic analysis of the related deposits in the vicinity of the volcano and in areas extending away from it. Investigators will compile and analyze all available photographic images, pre- and post-eruptive seafloor maps, as well as analyze sediment cores and ash textures. The project also includes analysis and interpretation of stratigraphic, geochemical, and other associated datasets. A specific focus of the research is determining the role that volatiles such as H2O, SO2, and sulfur played in the eruption. Goals of the research are to determine: (1) what combination of magma ascent rates and conduit processes caused the formation of a subaerial eruption plume from water depths of more than 1600 m; (2) if the data can shed light on the outstanding controversy regarding the lack of fine ash in deposits now found on land but that were derived from subaqueous eruptions; and (3) whether density currents that result from eruption column collapse are the primary transport mechanism for mass sediment flux away from the volcano or if other processes dominate. Broader impacts of the research include significant undergraduate training in research and state of the art field and laboratory scientific techniques, as well as cross training and video presentations that will link together all of the researchers and students at the institutions involved. Additional impacts include international collaboration with New Zealand scientists and the creation of a new, international body to study submarine volcanoes and the impacts of their explosive eruption. Also included are presentations to local community groups and K-12 schools, impacts for geohazards and disaster planning, support of an institution in an EPSCoR state, and support of an early career investigator whose gender is under-represented in the sciences and engineering.

海底有成千上万座火山。目前尚不清楚在任何给定的时间有多少这样的火山在喷发，因为大多数火山都被数百到数千英尺的水覆盖，这些水阻止了喷发产物逃逸到大气中或海洋表面，而海洋表面可以被船只、飞机或卫星发现。同样，我们也不知道这些海底火山中有多少会爆发，产生大量的火山灰和浮石，这些火山灰和浮石随后被水流扩散，或者导致火山斜坡不稳定，从而导致海啸。由于海底喷发，特别是那些爆炸性的海底喷发，是隐藏在视线之外的，我们对它们如何运作、喷发产物和分布以及潜在的地质灾害的了解几乎是未知的。幸运的是，在2012年7月，人们发现了一个200平方公里的浮石筏漂浮在西太平洋的海面上，就在水下1600米的阿弗尔火山上方，这表明这里发生了一次大爆发。利用这一事件，该项目对火山喷发进行了重大的科学调查。这项研究包括对火山、喷发和相关喷发产物及其在起源地附近和远处的分布进行全面的物理和化学研究。通过使用最先进的机器人车辆的海洋巡航，调查人员将收集样本和沉积物岩心，并创建该地区的海底照片马赛克。这项研究还包括对火山附近和远离火山的地区的相关沉积物进行高分辨率海底测绘和地层分析。调查人员将汇编和分析所有可用的摄影图像、火山爆发前后的海底地图，并分析沉积物岩心和火山灰结构。该项目还包括地层学、地球化学和其他相关数据集的分析和解释。研究的一个重点是确定水、二氧化硫和硫等挥发物在火山喷发中所起的作用。研究的目的是确定：(1)岩浆上升速率和管道过程的什么组合导致了水下1600米以上的地面喷发羽流的形成；(2)如果这些数据能够阐明关于目前在陆地上发现的、但来自水下火山喷发的沉积物中缺乏细灰这一悬而未决的争议；(3)喷发柱崩塌产生的密度流是否是大量沉积物离开火山的主要运输机制，还是其他过程起主导作用。这项研究的广泛影响包括在研究和最先进的领域和实验室科学技术方面进行重要的本科培训，以及将所有相关机构的研究人员和学生联系在一起的交叉培训和视频演示。其他影响包括与新西兰科学家的国际合作，以及建立一个新的国际机构来研究海底火山及其爆炸性喷发的影响。还包括对当地社区团体和K-12学校的演讲，对地质灾害和灾害规划的影响，对EPSCoR州的机构的支持，以及对科学和工程领域性别代表性不足的早期职业调查员的支持。