Sicknesses, Dying Trees Blamed On Seeping Gas Carbon Dioxide Escaping From Active Magma Under Ski Area In California
Five years ago, trees began mysteriously to wither and die on California’s popular Mammoth Mountain ski area.
Then a Forest Service official nearly suffocated when he took refuge from a storm in a snowbound cabin. Other workers said they felt sick. Public campgrounds were shut.
Today, scientists are reporting a single cause for all these events: Invisible carbon dioxide gas is seeping in huge amounts from within Mammoth Mountain, an ancient volcano.
About 100 acres of trees are dead and dying, the researchers say. For people, the main concern is suffocation from the heavier-than-air gas, which collects in low areas and enclosed spaces.
Concentrations of carbon dioxide are being closely monitored in recreational areas, officials say.
“There really is no health or safety issue, and use of the area has not dropped,” said Fred Richter of the U.S. Forest Service in the town of Mammoth Lakes.
But, said Christopher Farrar of the U.S. Geological Survey, “it’s an unusual occurrence worldwide - the way it’s killing the forest off with this invisible kind of emission.”
“And it’s an indication there is an active magma system under the mountain,” said Farrar, a hydrologist. Magma is molten rock.
Scientists say a series of earthquakes under Mammoth Mountain in 1989 signaled that magma was thrusting its way closer to the surface of the volcano, near the California-Nevada border. As the magma rises, it releases carbon dioxide trapped within it, and the gas seeps through to the surface.
Farrar and another scientist with the Geological Survey, Michael L. Sorey, along with other researchers are reporting their findings in today’s issue of the journal Nature. They estimate that some 1,200 tons of carbon dioxide are escaping daily. “If you dig a hole in the ground and throw some dust in, you can see it coming back at you” as the gas seeps out, Sorey said.
Carbon dioxide normally makes up less than 1 percent of air, and in high concentrations it can displace oxygen and asphyxiate animals or humans. Scientists don’t know exactly how it’s killing the trees of Mammoth Mountain, but they suspect the gas is preventing their root systems from taking in nutrients.
A soil-gas survey begun last year revealed concentrations of carbon dioxide ranging from 30 to 96 percent in the areas where trees have died, the scientists report.
When the trees began dying about 1990, Forest Service officials blamed dry conditions. In the winter of 1990, Richter was on a ski patrol when he sought shelter from a snowstorm in a small cabin. Soon he found himself breathless, his heart racing. He quickly left the cabin.
The mystery continued when maintenance workers experienced similar episodes. It was not until Farrar and other scientists began to suspect carbon dioxide gas that the pieces of the puzzle came together.