As mine crews face unstable shafts, the search for a missing Pennsylvania grandmother intensifies.

On Wednesday, the search for the grandmother who fell into a massive sinkhole in Pennsylvania continued, as authorities encountered unstable sections of the abandoned mine beneath the sinkhole.

On Dec. 2 in Marguerite, Pennsylvania, Elizabeth Pollard, 64, disappeared while searching for her lost cat Pepper. She was parked near a local restaurant with her five-year-old granddaughter in the car at the time.

The former Marguerite Mine, which was last operated in 1952, is believed to have caused sinkholes in the sparsely-populated village of Marguerite. Authorities suspect that Pollard fell into this mine.

Despite the unstable condition of certain parts of the abandoned coal mine, crews remained hopeful that 64-year-old grandmother Pollard would be found alive.

On Wednesday, John Bacha, the Fire Chief of Pleasant Unity, stated that the crews arrived at the location where Pollard is thought to have fallen, but they did not find any evidence of her.

The operations officer of the mission, Bacha, stated that mud may have relocated her to a different area in the mine.

"Bacha explained that they had arrived at the location they had intended, where they believed she was located. They had visited that spot before. However, they were unsure of what had happened at that specific point. Perhaps the muddy terrain had pushed her in a particular direction. There were multiple seams in the mine that intersected at that location."

Officials hope that Pollard is still alive, despite mixed conditions. Despite nightly temperatures dropping to freezing early this week, officials have stated that parts of the sinkhole still have sufficient oxygen levels.

"Bacha informed KDKA on Tuesday that all oxygen levels were ideal, with no carbon monoxide, explosive gases, or anything else present."

"We still have hope that there's a void and we'll be able to get there because the atmosphere has been perfect at this point."

The incident is being investigated by authorities. No further information is available.

The Associated Press contributed to this report.