Mantle controls on magmatic-volcanic cycles at basaltic volcanoes: An isotopic probe of the Pu'u 'O'o, Halema'uma'u, and 2018 Leilani eruptions of Kilauea Volcano

壮观的2018年基拉韦厄火山的莱拉尼裂谷喷发吸引了美国和世界各地的夜间新闻观察者和互联网冲浪者的注意，它成为夏威夷岛居民的破坏性火山危机。2018年的火山事件包括基拉韦厄两次持续熔岩喷发的结束，一次大规模（6.9级）当地地震，以及火山山顶区域的大规模（约0.8立方公里）爆炸性坍塌，破坏了夏威夷火山国家公园的道路和基础设施。在2018年的三个多月里，大量新的熔岩（0.8立方公里）从Leilani Estates的基拉韦厄下东裂谷带的裂缝中喷发出来，摧毁了大约700所房屋。这次火山爆发的规模（即，美国地质调查局夏威夷火山观测站的科学家蒂娜·尼尔说，这次火山喷发的速度和破坏程度“在现代记录中确实是前所未有的”。关于控制2018年火山事件的岩浆过程，我们知之甚少。在这项研究中，从三个基拉韦厄火山喷发，每隔约20公里的熔岩样本的成分的时间变化，将被用来跟踪通过火山的管道系统作为时间和空间的函数的岩浆批次的运动。这些结果将被用来检验一个假设，即2018年莱拉尼裂谷喷发是由至少一个大型幔源岩浆批次输送到一个已经拥有异常大量储存岩浆的火山建筑物而积极驱动的。这项研究有可能揭示神秘的地幔控制基拉韦厄火山的行为和危害。作为本研究的一个组成部分，将创建一个教育模块，通过角色扮演模拟2018年基拉韦厄火山事件，并将其发布在夏威夷火山和灾害教育科学教育资源中心（SERC）网站上。基拉韦厄经历了几十年到几个世纪的时间尺度上的主要喷发与爆炸性火山活动的长期周期，后者通常与山顶坍塌和/或破火山口形成有关。2018年的事件可能标志着基拉韦厄火山周期的高潮。来自这座火山的熔岩显示出系统的化学物质（例如，Nb/Y）和同位素（例如，206 Pb/204 Pb的变化主要受地幔源区不均一性和熔融作用的影响。这些幔源岩浆成分的变化表明，基拉韦厄也经历了独特的岩浆旋回，其中一些与长期火山旋回相吻合。一个重要的项目目标是测试这样一种想法，即基拉韦厄的长期火山循环最终是由地幔过程驱动的，包括（1）在异质地幔中产生成分不同的岩浆批次，以及（2）这些岩浆批次从源头到地表的运输。基拉韦厄的岩浆-火山旋回可能由两种机制引起。一种机制，基本上是被动的，是与耐火地幔源相关的部分熔融程度的下降，岩浆供应率下降，以及随后的中断首脑会议岩浆管道系统。这对上一个岩浆火山循环很重要，该循环以1924年的山顶坍塌和爆炸性喷发结束。另一种机制--主动驱动--与更肥沃的地幔源的高度部分熔融、高速率的岩浆供应以及来自地幔的一个或多个大型岩浆批次的有力输送有关。对2018年事件的这一假设将使用来自（1）2018年莱拉尼裂谷喷发，（2）普乌奥裂谷喷发的最后十年（1983-2018）和Halema'uma' u火山口内的熔岩湖（2008-2018年）该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的评估被认为值得支持。影响审查标准。

The spectacular 2018 Leilani rift eruption of Kilauea Volcano captivated the attention of nightly news-watchers and internet-surfers around the U.S. and the world, and it became a destructive volcanic crisis for residents of the Island of Hawaii. The volcanic events of 2018 included the end of two sustained lava eruptions at Kilauea, a large (magnitude 6.9) local earthquake, and a voluminous (~0.8 km3) explosive collapse of the volcano’s summit region that damaged roads and infrastructure in Hawaii Volcanoes National Park. Over three months in 2018, a large amount of new lava (0.8 km3) erupted from fissures on Kilauea’s Lower East Rift Zone at Leilani Estates and destroyed ~700 homes. The scale of this eruption (i.e., its high effusion rate and level of destruction) was “truly unprecedented in the modern record” according to Tina Neal, the Scientist-in-Charge at the Hawaiian Volcano Observatory of the U.S. Geological Survey. Very little is yet known about the magmatic processes that controlled the volcanic events of 2018. In this study, the temporal changes in the composition of lava samples from three Kilauea eruptions, each separated by ~20 km, will be used to track the movement of magma batches through the volcano’s plumbing system as a function of time and space. These results will be used to test the hypothesis that the 2018 Leilani rift eruption was actively driven by the delivery of at least one large mantle-derived magma batch to a volcanic edifice that already held an unusually large amount of stored magma. This research has the potential to reveal the enigmatic mantle controls on the behavior and hazards of Kilauea Volcano. An educational module, simulating the volcanic events at Kilauea in 2018 through role playing, will be created and published on the Science Education Resource Center (SERC) website for Hawaiian Volcanoes and Hazards Education as an integral part of this study.Kilauea experiences long-term cycles of dominantly effusive vs. explosive volcanic activity on a time scale of decades to centuries, with the latter often associated with summit collapse and/or caldera formation. The events of 2018 likely mark the culmination of a volcanic cycle at Kilauea. Lavas from this volcano display systematic chemical (e.g., Nb/Y) and isotopic (e.g., 206Pb/204Pb) variations on time scales of years to centuries due to its mantle source heterogeneity and melting processes. These mantle-derived changes in parental magma composition indicate that Kilauea also experiences distinctive magmatic cycles, some of which coincide with the long-term volcanic cycles. An important project goal is to test the idea that the long-term volcanic cycles at Kilauea are ultimately driven by mantle processes, including (1) the generation of compositionally distinct magma batches within the heterogeneous mantle and (2) the transport of these magma batches from the source to the surface. Kilauea’s magmatic-volcanic cycles may be caused by two mechanisms. One mechanism—essentially passive—is related to a refractory mantle source-related decrease in the degree of partial melting, a decline in the magma supply rate, and a subsequent disruption of the summit magmatic plumbing system. This was important for the previous magmatic-volcanic cycle that ended with summit collapse and an explosive eruption in 1924. The other mechanism—actively driven—is related to high degrees of partial melting of a more fertile mantle source, a high rate of magma supply, and the vigorous delivery of one or more large magma batches from the mantle. This hypothesis for the events of 2018 will be tested using the chemistry and Pb, Sr, and Nd isotope ratios of lava samples from (1) the 2018 Leilani rift eruption, and (2) the final decade of the long-lived Pu’u ’O’o rift eruption (1983-2018) and summit lava lake within Halema’uma’u Crater (2008-2018).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.