Scientists monitoring volcanic activity in the Mammoth area have measured an increase in carbon dioxide emissions but say there is nothing to indicate an imminent eruption.
Still, the emissions have prompted the closure of a campground at Mammoth Mountain, a popular skiing and outdoor recreation region 220 miles northeast of Los Angeles.
Emissions have risen to 1,200 metric tons a day - as high as at many active volcanoes, and two to three times higher than at Mammoth last year, U.S. Geological Survey scientist David Hill said.
The higher emissions and an increase in earthquakes this year have led the USGS to pay close attention to the Mammoth Lakes region.
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