The sharp, “toxic”-seeming odor that residents throughout Southwest Washington and into Oregon smelled on Sept. 22-23 remains a mystery. But the process of elimination continues.
Large industries in the area reported no unusual leaks or releases on or around the day the odor swept down the I-5 corridor. Railroads also reported no issues.
Now scientists at the U.S. Geological Survey have said the odor wasn’t caused by volcanic activity.
The Cascades Volcano Observatory has two monitoring stations at Mount St. Helens, the USGS said in a statement.
“One is called ‘SNIF’ and is located in the crater,” the agency reported. “It measures the compositions of gases (water vapor, carbon dioxide, sulfur dioxide, hydrogen sulfide) coming from vents on the 2004-08 lava dome. The other station, located northeast of the crater, measures the amount of sulfur dioxide emitted from Mount St. Helens.
“Together, these two monitoring stations show that there has not been an increase in the composition or amount of gases being emitted from Mount St. Helens,” the agency continued. “In fact, Mount St. Helens is presently releasing only very small amounts of water vapor, carbon dioxide and hydrogen sulfide, which is consistent with background behavior.”
The USGS added that it is “very confident in the measurements from SNIF,” adding: “CVO crews were also conducting field work at Mount St. Helens on September 24 and did not report any significant or new smells.”
Volcano emissions, scientists at the volcano observatory said, tend to smell like “dry, dusty rock.”
