The U.S. will slash its estimate of undiscovered Marcellus Shale natural gas by as much as 80 percent after a updated assessment by government geologists.

The formation, which stretches from New York to Tennessee, contains about 84 trillion cubic feet of gas, the U.S. Geological Survey said today in its first update in nine years. That supersedes an Energy Department projection of 410 trillion cubic feet, said Philip Budzik, an operations research analyst with the Energy Information Administration.

“We consider the USGS to be the experts in this matter,” Budzik said in an interview. “They’re geologists, we’re not. We’re going to be taking this number and using it in our model.

The formation, which stretches from New York to Tennessee, contains about 84 trillion cubic feet of gas, the U.S. Geological Survey said today in its first update in nine years. That supersedes an Energy Department projection of 410 trillion cubic feet, said Philip Budzik, an operations research analyst with the Energy Information Administration.