DataSheet1_Use of Pele’s tears and spheres as an indicator of lava fountain height in Hawaiian volcanoes.docx

Lava flows have presented the greatest hazard to human property during the most recent eruptions of Hawaiian volcanoes, and lava fountains are a source of these lava flows. The height of Hawaiian lava fountains reflects the exsolved gas content of the magma that controls eruption intensity. However, fountain height is not always observed, so we sought a proxy to estimate fountain heights of eruptions that were older or otherwise unobserved. Here, methods are described to empirically derive a relationship between the modal diameter of vesicles within Pele’s tears and spheres and lava fountain height, using samples of Pele’s tears produced during the last eruptions of Kīlauea Iki (1959) and Mauna Ulu (1969). The tears used to develop these relationships were approximately 1 to 4 mm in diameter. Additionally, since lava fountains 50–580 m high were used, the relationships we describe may only describe lava fountains in this height range. The strongest empirical relation follows the trendline Hmax = −2575d + 820, where Hmax is maximum lava fountain height and d is modal vesicle diameter. This empirical relationship may be applied to sub-Strombolian eruptions of tholeiite basalt that were not directly measured or observed to assess long-term shifts in lava fountain heights and thus the exsolved gas contents of a volcanic system. While the same conceptual framework can be applied beyond Hawai’i, the quantitative empirical relation may be slightly different in different systems, depending on total dissolved volatiles, magma chemistry and other factors.

在夏威夷火山近年的喷发事件中，熔岩流对人类财产造成的威胁最为突出，而熔岩喷泉正是这类熔岩流的形成源头。夏威夷熔岩喷泉的高度，直接反映了控制喷发强度的岩浆析出气体含量。然而，熔岩喷泉的高度并非总能被直接观测，因此我们希望找到一种替代指标，用以估算历史上或未被观测到的喷发的喷泉高度。本文介绍了基于经验推导关联关系的方法：利用基拉韦厄伊基（1959年）与冒纳乌鲁（1969年）末次喷发产生的佩莱泪石（Pele’s tears）样本，建立佩莱泪石与球状体的气孔众数直径和熔岩喷泉高度之间的定量关系。用于构建该关联关系的佩莱泪石直径约为1至4毫米。此外，由于本次研究所用的熔岩喷泉高度介于50至580米之间，因此本文所述的经验关系式仅适用于该高度区间内的熔岩喷泉。最优的经验关系式遵循趋势线Hmax = −2575d + 820，其中Hmax为最大熔岩喷泉高度，d为气孔众数直径。该经验关系式可应用于未被直接测量或观测的拉斑玄武岩亚斯通博利式（sub-Strombolian）喷发，以评估熔岩喷泉高度的长期变化，进而反演火山系统中的析出气体含量。尽管相同的概念框架可推广至夏威夷以外的火山区域，但不同火山系统的定量经验关系式可能会因总溶解挥发分、岩浆化学性质等因素而存在细微差异。