The mudslide is covering the highway's southbound lane about a quarter-mile south of Jones Road.
State Department of Transportation workers are at the top of the hill above the slide, cutting down trees that were loosened by the hillside below giving out.
"They're concerned about some of the more trees that may come down, so as soon as they're able to do that they can determine what the next move will be," said a DOT spokesman.
Small slides are not uncommon along this stretch of highway, but most of them simply slough into the ditch along the roadway. In this case, the volume of loose mud and debris was too much.
Only northbound traffic was getting through as of 7 a.m., but crews are planning to allow alternating traffic through as the morning progresses.