Large enhancements of the BrO total column have been detected from analysis of nadir earthshine UV-visible radiance observations by the GOME-2 satellite instrument in the vicinity of the Kasatochi volcano (Alaska) during several days after its eruption on the 7 August 2008. The transport of the volcanic plume has been simulated using the FLEXPART dispersion model, and evidence is found that the injection altitude of the BrO plume was located between 8 and 12 km altitude, i.e., in the upper troposphere/lower stratosphere region. Based on these results, the total mass of reactive bromine emitted by the volcano is estimated to be in the range from 50 to 120 tons. Copyright 2009 by the American Geophysical Union.