Repeat Terrestrial LiDAR Scanning at Kilauea Volcano Reveals Basaltic Lava Lake Surface Slope, Structure and Micro-pistoning

Abstract:

In an attempt to better understand the spatial and temporal relationships between lava lake behavior and its surface topography, we conducted repeat, high-speed terrestrial LiDAR surveys of Kīlauea Volcano’s Overlook Crater lava lake surface on January 16, 2013 and December 17, 2013. These scans revealed large- and fine-scale structure not visible in other topographic data sets. For both surveys, the LiDAR sensor was located directly above the Overlook Crater on the edge of the Halema’uma’u Crater, and was tilted 45^o towards the lava lake. On January 16, 2013, five-second scans were collected every 2-minutes over 200-minutes, resulting in ~25 points/ m², and covering the lower walls of the Overlook Crater and the lava lake surface. Similarly, on December 17, 2013, one-second scans were collected every 30-seconds over 240-minutes during a transient deflation-inflation deformation event, resulting in ~6 points/m². In addition, high-resolution scans of the crater walls and lava lake were captured at the start of both surveys.

We derived a number of products and measurements from these 3-dimensional time-lapse data. The slope of the lava lake was measured in each scan, and it fluctuates as lake convection regime, areas of upwelling and downflow, and crustal plate velocities vary. Areas of upwelling were consistently ~0.6m higher than areas of downwelling at any point in time, and the migration of areas of upwelling on the lake surface were coincident with areas of intense outgassing. Velocities of lava lake crustal plates averaged 0.354 m/s near the center of the lake surface on December 17, 2013. From the high-resolution scans collected at the start of both surveys we measured sub-meter lava lake fluctuations over time that may illustrate micro-pistoning in the magma column.

These preliminary results raise several questions: 1) do lava lake slopes change spatially and temporally, and what eruption variables are linked to such changes; 2) do lava lake levels change over time periods ranging from seconds to minutes, and are these changes related to outgassing and upwelling variations; 3) are fine-scale structures, such as surface waves that traverse the lake, related to observable processes (such as rockfalls), lake surface slope, and outgassing rates?