Study Finds Volcanic Activity in Cascades
The Cascade Range is pouring tons of carbon dioxide into the atmosphere, although another volcanic eruption like Mt. St. Helens is unlikely anytime soon, according to a new study.
Large amounts of the greenhouse gas have been found in the cold springs that supply most of the rivers in the central Cascade Range, indicating a high level of underground volcanic activity under the long chain of mountains that stretches from California to Canada.
“The carbon dioxide is coming from underground magma, or hot liquefied rock,” said Michael Manga, a University of Oregon geology professor who led the study.
“We have long suspected underground volcanic activity, but until now we didn’t have any hard evidence for it--no ‘smoking gun,’ ” Manga said.
For the last five years, Manga and his research team have been testing water from many of the large springs in central Oregon, including the headwaters of the Metolius River, famous for its trout fishing.
The geology of the Pacific Northwest and the prevalence of volcanic rock provided the team with a “window” to the subduction zone--the place where huge plates of Earth’s crust collide, Manga said.
“The system we’re dealing with in the Northwest is almost unique in the world,” he said.
“These volcanic rocks are so permeable, all the snowmelt goes into the ground, and the ground water comes out in springs. All the information about the volcanic activity goes into the ground water. Without the water in the springs, we’d have no way of determining what’s happening.”
Hot, liquefied rock contains many dissolved gases, in much the same way that champagne holds gases so that, once the cork is popped, it turns into bubbles.
Scientists at the U.S. Geological Survey’s Cascades Volcano Observatory in Vancouver, Wash., have been conducting aerial surveys of the Cascade Range for years. They say the Oregon study, published in the journal Geology in October, supports their observations that the mountains are sending nearly a ton of carbon dioxide per mile into the atmosphere every day.
Carbon dioxide is a “greenhouse gas” linked to global warming. The study may help researchers determine how much has been released by natural processes in the past compared to the huge volumes now being released by automobiles, coal-fired electricity plants and various industries.
*
“A ton per day per mile is a lot less than if you were to take measurements of the cars zooming up and down Interstate 5,” said Ed Klimasouskas of the USGS volcano lab.
He said the research also backs up USGS studies that indicate the Northwest is unlikely to have another volcanic eruption like the May 1980 blast that blew off the top of Mt.St. Helens, just north of Portland.
“Nothing is going to erupt anytime soon out here,” Klimasouskas said. “And geologic time is very, very slow.”
