UNDERSTANDING LAVA LAKES USING A NOVEL RADAR ALTIMETER

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).

User engagement is an intrinsic part of our project because of the synergy of research and operational monitoring that will be achieved with the U.S. Geological Survey - Hawaiian Volcano Observatory (HVO).
We identify three groups of beneficiaries of our research:

(i) The USGS-HVO will benefit from the installation of a sophisticated and bespoke radar altimeter, which will enable operational surveillance of the lava lake level at Kilauea. This will contribute to assessment of volcanic activity, and thereby to HVO's role in risk reduction (up to 3 million people visit the Hawai'i Volcanoes National Park annually). The shift in activity to the summit crater of the volcano has resulted in closure of part of the National Park to the public but visitors can still be exposed to hazards associated with acid gas and aerosol emissions from the lava lake depending on prevailing winds. Because lava lake level is such a key descriptor of the state of the magmatic system, the installation of the proposed radar device will represent a significant advance in the operational work of HVO.

(ii) The wider (international) volcano observatory community, especially those concerned with monitoring basaltic volcanoes, stands to benefit from increased knowledge of magmatic processes, in addition to developments in interpretation of multi-parameter datasets. These advances will arise through the development and testing of hypotheses throughout the project, and the refinement of models to explain and interpret cycles and transitions that characterise many aspects of "open-vent" volcanic behaviour.

(iii) Industrial beneficiaries are expected from within the radar community, including civil and defence companies that UCL already collaborates with on other projects. The technology developed by the project will enable high precision range measurements using novel cross-correlation techniques and allow the acquisition of continuous time-series data sets. The project will greatly contribute to the skill set and experience of the named Researcher (Dr. Nial Peters), who will gain expertise in radar engineering, time-series analysis, fieldwork planning and making international collaborations work. This combination of skills in addition to the opportunities for professional networking across a range of research areas and institutions will build further his expertise and recognition ahead of the next stage of his research career.