QUANTIFYING VOLUMETRIC CHANGES AT THE OVERLOOK PIT OF KILAUEA VOLCANO THROUGH TERRESTRIAL LASER SCANNING

The shape of the Overlook pit, at the southeast edge of Kilauea Volcano’s Halema’uma’u Crater, has evolved dramatically due to wall collapse and accretion of lava and tephra since its formation in March 2008. Contained within the pit is an active lava lake whose level fluctuates with changes in the summit magma reservoir and associated plumbing system. Quantifying the pit’s topographical changes has been difficult due to the technical limitations of previous sensors and data processing, and the presence of a thick gas and ash plume that interferes with the emitted pulse and hampers the use of single-return LiDAR systems. In recent years, advancements in ground-based LiDAR scanners have enhanced our ability to capture topographic data in a diversity of volcanic settings at the highest spatial and temporal resolutions possible. Moreover, advancements in waveform digitization have significantly improved the acquisition of dense topographic data in environments where gas emissions have historically hampered efforts. Using LiDAR scanning, we developed a methodology that allows for the rapid and accurate measurement of the geometry of the Overlook pit and its lava lake during biannual LiDAR surveys throughout 2012 and 2013.

Our research focuses on developing a methodology for quantifying volumetric changes between survey dates that is capable of differentiating between areas of fresh rock and tephra accretion and volume loss from the pit walls. Previously available methods for change detection capture only the net volume difference, whereas our approach allows us to successfully delineate both loss and gain. Though this study focuses on a cylindrical pit, our methodology may be applied in a variety of complex landscapes for rapid acquisition and processing of LiDAR data to monitor hazardous areas and identify topographical change.