USGS geologists collect gas samples around the dome. Samples were gathered from vents on the dome and crater floor, and were used to monitor changes in chemical composition. Additionally, sulfur dioxide gas was measured from a specially-equipped airplane before, during, and after eruptions to determine "emission rates" for the volcano. During eruptions, emission rates typically increased to 5 to 10 times their pre-eruptive value.
USGS geologists collect gas samples around the dome. Samples were gathered from vents on the dome and crater floor, and were used to monitor changes in chemical composition. Additionally, sulfur dioxide gas was measured from a specially-equipped airplane before, during, and after eruptions to determine "emission rates" for the volcano. During eruptions, emission rates typically increased to 5 to 10 times their pre-eruptive value.
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