Intercom Online......February 11, 1999


An earthquake beneath a dormant volcano in Mammoth Mountain, Calif., above, has caused carbon dioxide to seep from the ground at toxic levels. At right, researchers Derrill Kerrick, professor of geosciences, left, Giovanni Chiodini of Naples, Italy, and John Rogie, geosciences graduate student, set up their monitoring equipment on Mammoth Mountain.

Volcanic gas releases found to be
more complex than expected

By A'ndrea Messer
Public Information

Since an earthquake rumbled beneath the volcano in 1989, carbon dioxide has been seeping out of the ground in areas of Mammoth Mountain, Calif., killing trees and posing a health hazard in this ski resort area. Now, continuous carbon dioxide monitoring by researchers shows that this gas flow is much more complicated than previous measurements indicated.

In the past, the carbon dioxide levels seeping from the areas of tree kill were measured once a year, said John Rogie, graduate student in geosciences.

"If the gas flux was lower than the previous year, it was thought that the carbon dioxide degassing rate was continually decreasing," he said.

However, last year, Rogie monitored the area for a 24-hour period and found that the flux of carbon dioxide varied by up to a factor of three throughout the day.

"The 24-hour variation suggested that the system was very dynamic and that more than a single measurement was needed to tell us if the carbon dioxide rates were going up, staying the same or going down," said Rogie.

Working with Derrill M. Kerrick, professor of geosciences; Michael Sorey, U.S. Geological Survey, Menlo Park; Giovanni Chiodini, Osservatorio Vesuviano, Naples, Italy; and Giorgio Virgili, WEST Systems, Pisa Italy, Rogie designed a plan to continuously monitor the rate of carbon dioxide degassing in the 35-acre tree-kill area near Horseshoe Lake.

Rogie took continuous measurements of carbon dioxide flux and other environmental variables from August until the equipment was removed in early November, when snow levels reached more than two feet. As the snow accumulates, the carbon dioxide concentration where the snow meets the ground, and in the snowpack itself, builds up enormously and overwhelms the sensors.

Rogie found that the carbon dioxide flux was typically high in the afternoons and low in the mornings, which would seem to follow the 24-hour temperature cycle. However, the researchers have ruled out temperature as the cause of the variation because there also was a 12-hour cycle which may be linked to changes in barometric pressure.

Besides measuring carbon dioxide flux, the monitoring equipment measured barometric pressure, air temperature, humidity, wind speed, wind direction, soil temperature and soil moisture.

"Hopefully these measurements will help us determine how environmental factors like barometric pressure influence the degassing rate," Kerrick said. "We want to identify changes in the rate of gas ascent from depth by filtering out variation caused by weather-related phenomena."

This research will allow a better understanding of the dynamics of gas emission from volcanoes and provide an immediate warning device should the carbon dioxide emission rate suddenly increase.

Mammoth Mountain is considered to be a dormant volcano with its last eruption some 200 years ago, but may produce as much carbon dioxide as the active volcano Kilauea in Hawaii. Because the daily variability of carbon dioxide degassing is large, it is currently impossible to know exactly how much carbon dioxide is being emitted from Mammoth Mountain, but it is thought to be in the range of 400 to 1,200 metric tons per day.

From the Experts

Power outages can threaten food safety

Weather, good or bad, is getting easier to track and predict, but the sometimes capricious effects of bad weather -- stormy winds, torrential rains and lightning -- can knock out a home's power supply for hours or days. A Penn State Outreach and Cooperative Extension nutrition and food safety specialist said during emergencies, homeowners shouldn't be in the dark about food safety.

"When the power goes off for an hour or two, you don't have to worry about food safety," said Cathy Guffey, extension agent in Bradford County. "As long as you don't leave the freezer or refrigerator door open or open the door often, your food supply should be safe."

For longer outages, Guffey suggests some tips for the well-prepared homeowner.

* Thermometers. Buy thermometers for the refrigerator and freezer so you can track the temperature.

* Dry Ice. Adding dry ice to a freezer will stabilize temperatures from two to four days, depending on how full the freezer is. Put it in a cardboard box to keep it away from the contents of the freezer.

* Block Ice. Chilled temperatures can be maintained by placing block ice in a pan or watertight container in the refrigerator.

* Examine the food. If ice crystals are visible and its temperature has not gone above 40 degrees Fahrenheit, it is safe to refreeze. Discard any item with a strange odor or color. If the item has thawed but is still refrigerator cold, you can cook it and serve or refreeze the cooked dish.

According to Steve Knabel, professor of food science, some foods are less tolerant of exposure to warming temperatures over time.

* Fresh meats, poultry, cold cuts, hot dogs, eggs, casseroles, creamy salad dressings, cookie dough and milk should be thrown out if subjected to temperatures above 40 degrees Fahrenheit for more than two hours.

* Fruits, dried fruits, pasteurized fruit juices, flour, nuts and vegetables can be cooked or eaten raw provided there is no evidence of mold or a slimy feel.

* Cheeses can be eaten if they have been well wrapped, and butter and margarine can be kept as well, Knabel said.

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