EAGER: Collaborative Research: Has Recent Tectono-Magmatic Activity at Loihi (Kamaehuakanaloa) Seamount perturbed vent-fluid circulation and hydrothermal Fe export to the ocean?

EAGER：合作研究：洛伊希 (Kamaehuakanaloa) 海山最近的构造岩浆活动是否扰动了喷口流体循环和热液铁向海洋的输出？

• 批准号: 2220821
• 负责人: Everett Shock
• 金额: $ 2.04万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-06-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2220821&HistoricalAwards=false
• 关键词: EAGER; Collaborative; Research; Recent; Tectono

Has Recent Tectono-Magmatic Activity at Lōʻihi (Kamaʻehuakanaloa) Seamount perturbed vent-fluid circulation and hydrothermal Fe export to the ocean?Like volcanoes on land, submarine volcanoes are not continuously erupting but can remain dormant for long periods. Even while dormant, however, the magmatic heat present beneath a volcano’s surface can continue to drive hot springs in between eruptions. The focus of this study is hot springs at the Kamaʻehuakanaloa underwater volcano (previously known as Lōʻihi), situated about 30 miles south of the Big Island of Hawai’i which last erupted in 1996. Prior studies between the mid 2000’s and late 2010’s have shown that the multiple hot-springs associated with that last eruption, at the summit of the volcano have been cooling down continuously. This study will investigate whether two sets of recent earthquakes at Kamaʻehuakanaloa may have altered that cooling trend. In May 2020 earthquakes associated with magma intrusion into the chamber deep within the seamount were detected. In 1996 earthquakes similar to this accompanied a volcanic eruption. More recently still, in December 2021 the strongest earthquakes of any kind since the 1996 eruption were detected. This project will use a deep-diving robot to investigate whether lava was erupted on the seafloor during these earthquakes and also if the composition of the fluids (chemically altered seawater) flowing out of the seafloor at the volcano’s summit has changed.The Lōʻihi seamount (recently renamed Kamaʻehuakanaloa) last erupted in 1996, significantly reshaping its summit and creating three collapse pits. Inside one of these, Pele’s Pit, hot springs have been studied which exhibited temperatures in excess of 200°C immediately post-eruption. Since 2006, however, the multiple sites that have been subject to long-term study within Pele’s Pit and around its rim have shown more modest temperatures of 15-55°C which, further, have exhibited progressive cooling at a rate of 1-2°C over a 12-year period from 2006 to 2018 (the most recent year for which time-series data exist). Thermodynamic modeling of the fluids collected in 2018 has provided new insight that the subsurface hydrothermal circulation within this steep sided seamount may extend much deeper than is typical at mid-ocean ridges (which are more elongate and exhibit shallower-sloping ridge flanks). Further, a geochemical consequence of Lōʻihi’s unusual circulation pattern may account for the unusually Fe-rich nature of the vent-fluids emerging from the seafloor at this intra-plate setting, and their impact on the surrounding ocean, when compared to mid-ocean ridges vents. This project will extend the 2006-2018 time-series of vent studies at Lōʻihi to investigate whether the subsurface hydrothermal circulation system has been perturbed by two significant episodes of seismicity that have subsequently occurred, as detected by the US Geological Survey’s Hawai’i Volcano Observatory. In May 2020, a swarm of earthquakes was detected that were distinctive compared to all seismic activity since the volcano last erupted in May 1996 because they exhibited T-phase activity, recognized as being diagnostic of magmatic fluids migrating within the interior of the seamount and potentially indicative of magma replenishment. In December 2021, an even more pronounced episode of seismicity was detected, up to magnitude M4.9, which matched the strongest earthquakes detected during the 1996 eruptions. This project will use the ROV Jason to investigate whether the seafloor hydrothermal venting at Lōʻihi has been perturbed following these episodes of seismicity. The project will test the hypothesis that the earthquakes, detected by T-phase seismic signals, perturbed the deep hydrothermal circulation cell at Lōʻihi, which in turn should be detectable at the seafloor through changes in vent-fluid temperatures and geochemical compositions. Changes in seafloor morphology and locations of vent-sites compared to the previous ROV dives in 2018 may also be expected. Conversely, the null hypothesis would be that the vent-sites that have been studied since 2006 continue to cool progressively (each vent should then be 6±2°C cooler than when last studied in 2018) with compositions that will have changed accordingly. Importantly, proving this null hypothesis would still be scientifically valuable. It would extend the longest time series available for any intra-plate hydrothermal field worldwide and continue to collect pre-event data in anticipation of future extrusive volcanism at Lōʻihi that will occur.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.

最近在Lōihi（Kama'ehuakanaloa）的tectono-Magmagic活性是否扰动排气流体流通循环和水热Fe出口到海洋？如陆地上的火山，海底火山，不断腐烂，但可能会持续长时间持续时间。然而，即使休眠，火山表面下的岩浆热也可以继续驱动温泉。 The focus of this study is hot springs at the Kamaʻehuakanaloa underwater volcano (previously known as Lōʻihi), situated about 30 miles south of the Big Island of Hawai’i which last erupted in 1996. Prior studies between the mid 2000’s and late 2010’s have shown that the multiple hot-springs associated with that last eruption, at the summit of the volcano have been cooling down continuously.这项研究将调查卡玛·埃哈卡纳洛（Kama'ehuakanaloa）最近发生的两组近期地震可能改变了这种冷却趋势。在2020年5月，发现与岩浆侵入海拔深处的腔室有关的地震。 1996年，地震进行了火山喷发。最近，自1996年爆发以来，2021年12月在2021年12月发生了强烈的地震。该项目将使用一个深水的机器人调查这些地震期间的熔岩是否在海底爆发，以及是否在火山山顶上流出的笛子（化学变化的海水）的组成发生了变化。 Lōhihi海山（最近更名为Kama'ehuakanaloa）于1996年爆发，大大重塑了其峰会并创造了三个倒塌坑。在其中之一内，贝利的坑，温泉已经进行了研究，暴露于爆发后立即暴露于200°C的温度。但是，自2006年以来，在贝利坑中及其轮辋周围进行了长期研究的多个地点显示，在2006年至2018年（在最近的一年中，存在时间序列数据的最近年），在12年内，以1-2°C的速度暴露了15-55°C的适度温度，以1-2°C的速度暴露了渐进式冷却）。 2018年收集的流体的热力学建模提供了新的见解，即该钢两侧封口中的地下热液循环可能比近代山脊上的典型延伸得多（它们更细长并且存在更浅的斜脊脊）。此外，Lōhihi异常循环模式的地球化学后果可能是在这种板内环境中从海底散发出的通风河流体及其对周围海洋的影响的异常富裕的性质，与中等海洋的山脊相比。该项目将延长Lōihi的2006 - 2018年通风量研究时间序列，以研究地下水热循环系统是否受到随后发生的两个重大地震性发作的扰动，如美国地质调查局的夏威夷夏威夷火山观察者所检测到的那样。在2020年5月，发现一群地震与自1996年5月火山上次爆发以来的所有地震活性相比，这是与众不同的，因为它们暴露了T相活性，被公认为是在接缝内部迁移的岩浆烟的诊断，并潜在地表明了岩浆复制。在2021年12月，检测到更明显的地震性发作，直至M4.9级，这与1996年爆发期间发现的强烈地震相匹配。该项目将使用ROV Jason来研究这些地震性发作后，Lōihi的海底热液排气是否受到干扰。该项目将检验以下假设：T阶段地震信号检测到的地震扰动了Lōihi的深水热循环细胞，而该地震又应在海底通过通风流体温度和地球化学成分的变化在海底检测到。与先前的ROV潜水相比，海底形态的变化和通风口位置的变化也可能预计。相反，零假设将是自2006年以来所研究的通风线继续逐步冷却（然后，每个通风孔应比2018年上一次研究时的凉爽6±2°C凉爽），并具有相应变化的组合物。重要的是，证明这一无效假设仍然是有价值的。它将延长最长的时间序列，用于全球任何板内氢热场，并继续收集事前数据，以期预期将会发生在Lōihi的未来膨胀火山，这将发生。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子和更广泛影响的评估来评估的支持，并被视为珍贵的支持。