MONITORING CO2 GAS EMISSIONS AT LASSEN VOLCANIC NATIONAL PARK

Gas emissions are important indicators used to monitor magmatic activity. CO2 gas emission measurements from fumaroles, hot springs, and soil at Lassen Volcanic National Park (LVNP) in northern California marks the first of a three year series of monitoring. The primary sampling site is Sulfur Works (6890 ft elevation), located near the southwest entrance of LVNP. Soil temperatures at Sulfur Works range from 2.8-91.7 C in the top 20 cm. Water in hot springs is as hot as 90 C. CO2 measurements collected at hot springs and in the soil are made using portable CO2 monitors that use infrared gas analyzers (IRGA). Hot springs CO2 emissions range from 260-1400 ppm. Data indicate significant short term variations in near- surface CO2 concentrations, probably associated with proximity to hydrothermal vents. Diffusion of CO2 through the soil is calculated from the physical properties of soil and CO2 concentrations. The goal for the first stages of monitoring is to determine whether CO2 emissions vary significantly over the monitoring period, and whether there are any periodic changes in gas emission concentrations. Results of this work have potential use for long term monitoring similar to that completed at Mammoth Mountain in Long Valley Caldera (1). Our results will contribute to further characterization of the hydrothermal system at LVNP. (1) Rogie, et al., 2001