North-Central Section - 49th Annual Meeting (19-20 May 2015)

Paper No. 6
Presentation Time: 3:15 PM


HEAD, Elisabet M., Earth Science, Northeastern Illinois University, 5500 North St. Louis Avenue, Chicago, IL 60625 and CARN, Simon A., Geological and Mining Engineering and Sciences, Michigan Technological University, Houghton, MI 49931,

Nyamuragira volcano (D.R. Congo) is located in the western branch of the East African Rift, and emits low viscosity alkaline magma and large amounts of SO2 (up to 1 Mt/day) during eruptions occurring every ~1-3 years. Basaltic effusive eruptions with a volcanic explosivity index of less than 3, as is often the case with Nyamuragira, are thought to contribute volcanic gas mainly to the lower-mid troposphere and are not capable of higher altitude plumes. The SO2 plume from the November 2006 Nyamuragira eruption, however, was tracked with satellites as far as the west coast of the United States within the first few weeks of eruption, which suggests upper tropospheric emplacement. Determining the height and distribution of volcanic gas in the atmosphere is important because plume altitude will affect the lifetime and dispersion of SO2 and sulfate aerosol, having significant implications for local and global climate.

We constrained the 2006 Nyamuragira plume height using Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT), Atmospheric Infrared Sounder (AIRS), Microwave Limb Sounder (MLS), Multi-Angle Imaging Spectroradiometer (MISR), and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data. In addition, we aimed to refine the 2006 eruption SO2 emission estimates using ultraviolet (UV) measurements from the Ozone Monitoring Instrument (OMI). Plume height and OMI data interpretation are closely linked since the change in atmospheric properties (T, P, H2O content) with altitude affects the plume’s absorption of UV radiation. We found that the 2006 Nyamuragira eruption emitted 0.06 Mt of SO2 and the plume reached 15 km; the tropopause begins at 16-17 km at equatorial latitudes. This adds to the idea that historical effusive basaltic eruptions (e.g., Laki 1783) were capable of similar plume heights, allowing SO2 and resultant aerosols to remain longer in the atmosphere, travel farther around the globe, and affect global climate. The lower tropopause altitude (~9 km) at high latitudes indicates that less energetic basaltic eruptions are equally capable of injecting volcanic gas into the polar stratosphere.