A review of controls on lava lake level: insights from Halema‘uma‘u Crater, Kīlauea Volcano
A review of controls on lava lake level: insights from Halema‘uma‘u Crater, Kīlauea Volcano
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熔岩湖水位控制回顾：来自基拉韦厄火山 Halema‘uma‘u 火山口的见解
作者：
M. Patrick;D. Swanson;T. Orr
熔岩柱的高度是开放式火山活动的基本衡量标准，但几乎没有连续的长期数据来了解这一参数。最近（2008-2018年）在Kallauea火山山顶的熔岩湖活动提供了一个跟踪和了解控制熔岩水平的过程的机会，时间范围从几分钟到几年。我们回顾了最近公布的数据，并分析了2009-2017年期间Kamplauea峰会熔岩水平的长期记录。较长的时间尺度波动，在几天到几个月，有很强的正线性相关与地面变形，这表明他们反映了在山顶岩浆库的压力变化。较短的时间尺度波动，在几分钟到几小时内，与飞溅具有相反的关系（即，释气）强度-增加的释气降低了湖平面，反之亦然。因此，我们对长期熔岩水位数据的分析证实，Halema'uma' u的熔岩水位受这两种类型的过程控制：（1）与岩浆储层压力变化有关的过程（如岩浆供应速率）和（2）浅层释气波动（如气体活塞）。频率滤波可以隔离压力和放气驱动的熔岩水平变化的组成部分。时间序列分析表明，没有大的，持续的周期性熔岩水平;一个轻微的每两周振荡可能与地球潮汐，但不是连续存在。熔岩水平和变形之间的相关性的首脑会议表明，熔岩湖作为一个可靠的“测压仪”，跟踪熔岩水平随着时间的推移，因此可以提供一个侧面喷发的潜力的指示。我们表明，长期的跨学科监测是必要的，以区别控制熔岩水平的过程。
The height of the lava column is a fundamental measure of open-vent volcanic activity, but little continuous long-term data exist to understand this parameter. The recent (2008–2018) lava lake activity at the summit of Kīlauea Volcano provides an opportunity to track and understand the processes that control lava level over timescales ranging from minutes to years. We review recently published data as well as analyze the long-term record of lava level at Kīlauea’s summit during 2009–2017. Longer timescale fluctuations, over days to months, have a strong positive linear correlation with ground deformation, suggesting they reflect pressure changes in the summit magma reservoir. Shorter timescale fluctuations, over minutes to hours, have an inverse relationship with spattering (i.e., outgassing) intensity at the lake surface—increased outgassing lowers the lake level and vice versa. Our analysis of the long-term lava level data thus confirms that lava level at Halema‘uma‘u is controlled by these two types of processes: (1) those related to magma reservoir pressure changes (such as magma supply rate) and (2) shallow outgassing fluctuations (such as gas pistoning). Frequency filtering can isolate pressure- and outgassing-driven components of lava level change. Time series analysis indicates that there was no large, persistent periodicity in the lava level; a minor fortnightly oscillation might be related to Earth tides but was not continuously present. The correlation between lava level and deformation of the summit indicates that the lava lake acts as a reliable “piezometer”; tracking lava level over time may thus provide an indication of flank eruptive potential. We show that long-term interdisciplinary monitoring is necessary to discriminate the processes that control lava level.