National Aeronautics and Space Administration

Abstract. Sulfur dioxide clouds from three explosive eruptions of Crater Peak vent of Mount Spurr during the Summer of 1992 were detected, tracked, and measured by NASA's Total Ozone Mapping Spectrometer (TOMS). From the TOMS data we calculated that the August 18 eruption produced the largest sulfur dioxide emission of the three events as 400±120 kilotons (kt) SO₂ followed by the September 16-17 and June 27 eruptions (230±70 kt and 200±60, respectively). The June SO₂ plume remained primarily over eastern Alaska and Canada's Yukon province, and it was observed by TOMS for 7 days. The August cloud drifted southeast along Canada's Pacific coast before being carried eastward, and after 8 days it was finally viewed passing over England. The September cloud traveled the most rapidly of the three: southeast across Canada and the northern United States, then northeast over Toronto, and finally over Greenland 5 days later. TOMS data for the August and September eruptions revealed that the two gas plumes increased in SO₂ amounts over the first 2 days - well after the eruptions had ceased. The TOMS data and other available evidence suggest that significant quantities of hydrogen sulfide, in addition to sulfur dioxide, may have been explosively outgassed by these two eruptions. The maximum injection altitudes of the ash clouds, matching of SO₂ cloud positions to known wind conditions, and the dispersion rates of the gas clouds all suggest that at least half of the sulfur dioxide emitted by the Crater Peak eruptions reached the lower stratosphere.