19 Central American Volcanism - A Tribute to Bill Rose

Friday, 3 April 2009
8:00 AM - 12:00 PM

INTEGRATION OF HIGH TEMPORAL RESOLUTION SO2 EMISSION RATES AND GEOPHYSICAL DATA AT CENTRAL AMERICAN VOLCANOES

Paper number: 19-9
Program: Symposia Sessions
Time: 10:20 AM – 10:40 AM

Authors

Abstract

Recently developed ultraviolet cameras present a significant improvement in the field of volcanic SO2 measurements. Older instruments utilized for measurement of SO2 emissions in volcanic plumes (e.g., COSPEC, mini-DOAS) are often limited in their accuracy by plume and volcano geometry, uncertainties in plume velocity, plume variability over the course of a single measurement, and low temporal resolution (generally at least 1 minute per measurement, more often <10 measurements per day). In contrast, UV cameras, with their data's synoptic nature, allow for investigation of the high degree of variability in plumes and offer the opportunity to measure SO2 flow rates (as a proxy for volcanic emission rates) at any number of locations within the image, including at or very near the vent. Plume velocities can be derived from UV camera data time series, eliminating the often erroneous estimations of plume velocity based on wind speed. Temporal resolution of the SO2 dataset is also much improved with the camera able to yield SO2 emission rates at sampling frequencies approaching 1 Hz. The superior temporal resolution facilitates comparison to other volcanic datasets, such as seismicity, microgravity, and deformation.

UV camera time series from Fuego volcano, Guatemala, and Masaya volcano, Nicaragua indicate that SO2 flow rates at these volcanoes may double over the course of <10 minutes, and subsequently return to low levels on the same time scale. Though some of the variations in SO2 flow rate are apparently due to wind eddies or other small scale atmospheric variations near the vent, other variations are likely to be real variations in emission rate that are related to volcanic processes. These fluctuations are evaluated in relation to simultaneous acoustic and seismic datasets in an attempt to understand the nature of such fluctuations. We present the latest improvements to current algorithms for the processing of UV camera data, including advances in automatic derivations of plume velocity, as well as preliminary integration of camera-derived SO2 emission rates with other datasets from Fuego and other Central American volcanoes. The high temporal resolution of UV camera data offers a new opportunity for evaluation, alongside concurrent seismic and acoustic data, of variations in SO2 emission rate on a short time scale.