Moon Township road reopens after landslide

PENN HILLS, Pa. — A landslide in Moon Township closed University Boulevard Tuesday, several hours after a rock slide in Penn Hills forced the closure of a portion of Allegheny River Boulevard.

RAW VIDEO: Landslide closes portion of University Boulevard in Moon Twp.

The slide on University Boulevard, which is closed at Stoops Ferry Road, was reported shortly after 3:30 p.m. Officials said the road will be closed overnight between Route 51 and Campus Drive. Traffic was detoured onto Stoops Ferry Road until the road reopened Thursday morning.

Earlier on Tuesday, a rockslide in Penn Hills kept Allegheny River Boulevard closed for hours. The slide was reported about 10 a.m. between Sandy Creek and Nadine roads.

RAW VIDEO: Rock slide on Allegheny River Boulevard

Penn Hills police had said the road was expected to remain closed until about 6 p.m. while crews worked to clear debris. Work wrapped up sooner than expected, and the road reopened about 2 p.m.

The cause of the slide is not yet known, but it’s possible that recent rain contributed.

RELATED: What causes rock slides?

There has been at least a trace of rainfall in Pittsburgh for the last nine days. Since Friday, the area has picked up at least 1 inch of rain. On Monday alone, more than three-quarters of an inch of rain fell in a 6-hour window.

Rock slides occur when there is already a weakness in the slope, allowing rocks to move down. They can be triggered by earthquakes or when a slope becomes saturated with water. Water aids in the downslope movement of the debris, adding weight to the soil. Once it's heavy enough, rocks begin to slide.

Gravity eventually overcomes that friction between the top rock layer and the rock beneath it, causing that top layer to slide. It's an action that's similar to avalanches that send snow rushing down mountains.

Every year in the U.S., slides such as land, mud or rock can cause roughly $3.5 billion in damage and kill between 25 and 50 people.

Cox Media Group