Drones, Scopes, and Aerosols
Authors:   , Moyer Danielle Kimiko , Daeschler Edward B , Vanderkluysen Loÿc 
Published: December 2022

Volcanic emissions, ranging from gaseous clouds to ash-rich plumes, pose a complex hazard to those working and living near an active volcano. With over 9% of the world's population living within a 100 km radius of an active volcano, volcanic emissions have the potential to impact over 450,000,000 people (Small, C & Naumann, T, 2001). While not every active volcano is of imminent danger to the nearby populace, measuring and actively monitoring emissions from these volcanoes remains an important part of keeping local communities informed and prepared for potential activity. It is why the volcanological community is particularly interested in adapting, improving, and developing monitoring techniques to better understand the emissions produced by active volcanoes. In an effort to improve upon previous methods of monitoring emissions, I chose three different study areas to adapt measurement techniques that could be used in what was previously seen as too difficult or hazardous environments. At Sinabung Volcano, Indonesia, I mounted an optical particle counter (OPC) to a small Unoccupied Aerial System (sUAS) to measure particle size distribution and abundance of particles 40 [mu]m in size and smaller ([phi] <4.5). I flew the sUAS approximately 2-4 km downwind from the vent at Sinabung to create vertical and horizontal profiles of particulates and aerosols within the emission cloud. The measurements from these flights reported particle concentrations in ranges from 46-86 pcl/cm3 below the 0.46 [mu]m in diameter size throughout the moving emission cloud. These particle concentrations decreased in abundance to below 20 pcl/cm3 when particles were greater than 0.46 [mu]m in diameter, accounting for less than 2% of the total particles within the cloud. From this we concluded that the emissions we were able to measure that were produced at Sinabung during this time, June 2018, were most likely aerosols or ultra-fine ash (<10 [mu]m). While these particles pose no threat to aviation, they can cause unwanted respiratory irritation when inhaled over a long period of time. Continuing the study from Sinabung, I sought to focus further on the particulates that were often too small to be seen by the naked eye. Villarrica Volcano, Chile and its actively degassing lava lake provided optimum conditions to test the sUAS further while measuring particle size and abundance to better understand the particle size distribution within its emission cloud. In February of 2020, I flew a series of flights through the moving emission cloud above Villarrica Volcano's vent. I measured particle concentrations ranging from10-4,148 [mu]g/m3, with all particles smaller than 4 [mu]m in diameter, within the drifting volcanic cloud. The particles were most concentrated above the crater rim where the volcanic cloud was regularly forming with an average size of 0.35 [mu]m. This study successfully showed that the sUAS package, first developed for Sinabung Volcano, Indonesia could be adapted to different volcanic types and measure crucial information needed to monitor air quality for nearby populations. Lastly, I chose Yellowstone Volcano, USA to focus on emissions from another degassing volcano that faced its own difficulties when it came to measurements. Due the high water vapor content in the emissions produced within its many hydrothermally rich areas, measuring important gases for monitoring purposes, such as CO₂ (carbon dioxide) and SO2 (sulfur dioxide), becomes much more difficult than what was seen on volcanoes like Sinabung or Villarrica. I used the Open-Path Fourier Transform Infrared Spectroscopy, or OP-FTIR to collect spectra data on a wide range of gas species in hopes of contributing to the ongoing efforts to account for the average amount of CO₂ produced in the Yellowstone caldera. Concentrations ranged from 200 to 2,000 ppm, varying in averages depending on the site, weather, and field set up. These concentrations, obtained over the course of two expeditions in two years and was comparable to the gas sampling via MultiGas conducted in that same areas in early 2000. Sinabung, Villarrica, and Yellowstone volcanoes provided three separate study areas in which I could test, adapt, and contribute to ongoing monitoring efforts in heavily populated areas. While the study areas were vastly different on the surface, they all benefited from further monitoring of fine and ultra-fine particulates produced in their emissions. By utilizing new technology, such as sUAS, to tackle the hazards or working in a regularly erupting environment and adapting older technology like the OP-FTIR for difficult areas like a wet volcano, I was able to collect important emission data in situ to be used for continuing monitoring efforts and improvement of monitoring techniques.