UNDERSTANDING LAVA LAKES USING A NOVEL RADAR ALTIMETER

我们的目标是研究与岩浆脱气和输送动力学相关的瞬态、振荡和长期行为，这些行为反映在熔岩湖的水平、排放气体的组成和通量以及其他地球物理和大地测量参数中。我们将通过对两个截然不同的“实验室火山”（基拉韦厄火山和埃里伯斯火山）的熔岩湖的详细研究来实现这一目标。虽然两座火山都有熔岩湖，但它们的岩浆性质在组成、晶体含量、粘度和脱气方式方面有很大不同。这将使我们能够研究各种火山现象，并发展和评估与理解世界各地许多露天火山的行为有关的假设。对该项目特别重要的是，我们计划使用一种创新的专用雷达仪器获得高精度、高时间分辨率和持续的熔岩湖水位测量。这将是对已经用于其他环境应用的现有雷达系统的一种新颖的改编，并建立在我们已经设计和建造的原型雷达设备上，我们将在下一次埃里伯斯火山实地任务之前进行设计和建造。在目标火山，雷达观测将与从紫外和红外光谱（用于气体通量和成分）、热成像仪（用于湖表面辐射测量和速度测量）、重力测量（用于质量变化）、连续大地测量（表征地面变形）和地震学获得的操作和运动测量相结合。新的雷达仪器将被纳入夏威夷火山天文台的业务监视方案。我们在项目前半部分的重点将放在完善和安装雷达仪器上。在下半场，我们将利用传入的数据流，将它们与我们自己和其他辅助的目标熔岩湖观测相结合，并使用时间序列分析来识别熔岩湖循环和长期现象的时间演变，以及不同参数（例如，湖泊水位，气体通量，气体成分）之间的领先和滞后。这将有助于梳理出脱气、流变性、湖泊几何形状和喷发风格之间的关系和反馈（例如，Erebus的爆炸性与被动脱气）。该项目的一个关键成果将是发展假说，解释我们将在现场记录的熔岩湖水位、气体通量和化学、质量变化和表面变形的复杂变化。我们期望观察到的变化和对比的动态机制能够代表浅层（管道和熔岩湖）和深层（水库）过程。项目精神的关键是它结合了雷达仪器（UCL）和火山学（剑桥）方面的专业知识，以及英国项目成员与美国合作伙伴（美国地质调查局-夏威夷火山观测站和新墨西哥理工大学运营的埃里伯斯火山观测站）的密切合作。这是一个雄心勃勃的项目，我们希望通过它来改变我们对岩浆过程的理解，这要归功于电气工程、现场科学、复杂的数据处理和时间序列分析的计划协同作用。我们的目标是通过剑桥- nerc地球系统科学DTP招收一名博士生，以发展熔岩湖流体动力学的理论方面。该学生将与PI和指定研究员（尼尔·彼得斯博士）密切合作。

We aim to investigate transient, oscillatory and secular behaviour related to the dynamics of magma degassing and transport, and reflected in the levels of lava lakes, and in the composition and fluxes of emitted gases and in other geophysical and geodetic parameters. We will achieve this through detailed studies of the lava lakes of two contrasting "laboratory volcanoes" (Kilauea and Erebus). While both volcanoes host lava lakes, their magma properties differ significantly in terms of composition, crystal content, viscosity and degassing styles. This will enable us to examine a variety of volcanic phenomena and to develop and evaluate hypotheses pertinent to understanding the behaviour of many open-vent volcanoes around the world.Of particular importance to the project, we plan to acquire high-precision, high-temporal resolution and sustained measurements of lava lake level using an innovative and purpose-built radar instrument. This will be a novel adaptation of existing radar systems that have been used for other environmental applications, and builds from work on a prototype radar device that we are already designing and constructing ahead of our next field mission to Erebus volcano. The radar observations will be integrated, at the target volcanoes, with both operational and campaign measurements obtained from ultraviolet and infrared spectroscopy (for gas flux and composition), thermal imagers (for lake surface radiometry and velocimetry), gravimetry (for mass changes), continuous geodesy (to characterise ground deformation) and seismology. The new radar instrument will be integrated into the operational surveillance programme of the Hawaiian Volcano Observatory.Our focus in the first half of the project will be on perfecting and installing the radar instrumentation. In the second half we will capitalise on the incoming datastreams, integrate them with our own and other ancillary observations of the target lava lakes, and use time-series analysis to identify temporal evolution of lava lake cycles and secular phenomena, and leads and lags between different parameters (e.g., lake level, gas flux, gas composition). This will help to tease out relationships and feedbacks between degassing, rheology, lake geometry and eruptive style (e.g., explosive vs. passive degassing at Erebus). A key outcome of the project will be the development of hypotheses that explain the complex variations in lava lake level, gas flux and chemistry, mass change and surface deformation that we will have documented in the field. We expect the observed variability and contrasting dynamic regimes to represent both shallow (conduit and lava lake) and deeper (reservoir) processes. A key to the ethos of the project is its combination of expertise in radar instrumentation (UCL) and volcanology (Cambridge), and the close collaboration of UK project members with partners in the USA (the US Geological Survey-Hawaiian Volcano Observatory, and the Mount Erebus Volcano Observatory, which operates from New Mexico Tech.). This is an ambitious project through which we hope to transform aspects of our understanding of magmatic processes, thanks to the planned synergy of electrical engineering, field science, and sophisticated data processing and time-series analysis. We aim to recruit a PhD student through the Cambridge-NERC Earth System Science DTP to develop theoretical aspects of lava lake fluid dynamics. The student would work closely with the PI and named researcher (Dr. Nial Peters).