Gas sampling around the Mount St. Helens dome. Analyzed results us...

(Credit: Casadevall, Thomas. Public domain.)

Detailed Description

USGS geologists gathered samples by hand from vents on the dome and crater floor. 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.

Details

Image Dimensions: 3072 x 2048

Date Taken: Thursday, September 24, 1981