Enormous rockfall closes Colorado highway

Colorado Highway 145 is closed "indefinitely" after being hit by two huge rock blocks.

The incident occurred on May, 24, 2019 in the Highway between the municipalities of Cortez and Telluride. According to the Colorado Department of Transportation, the road was hit by a landslide consisting of debris, rock fragments and two enormous boulders "the size of a building". The impact of the collision was so forceful that the road settled by 2,5 meters.

"CO 145 between Cortez & Telluride is closed indefinitely due to a significant rock fall which occurred this afternoon. The slide is located approximately 12 miles north of Dolores, MP 22. The slide consisting of dirt, rock and two huge boulders which have destroyed the full width of the highway pavement, leaving a trench approximately eight feet deep across both lanes. The road is impassable at this time," Colorado Department of Transportation posted on Facebook.

Experts estimate that the height and the width of the larger boulder are about 15 meters and its weight is about 4,000 tons. The next step involves the removal of the rocks. Initially, the boulders will be drilled and blasted in order to break into smaller fragments that will be later removed. It is not clarified when the road will be operational again.

The rock fall initiated in a cliff, about 300 meters above the highway. Rock slides are usual especially during spring period as ice melts. However, such large boulders fall is unprecedented. "The loss of support from underneath, or detachment from a larger rock mass destabilizes the rocks and gravity does the rest. The criteria for rockfall is simply an exposure of broken rock, gravity, and a slope steep enough that when a rock detaches or dislodges from the ground surface, it will move down the slope rapidly. Complex interactions between physical parameters of both the rock and the slope cause the falling rocks to move down the slope in a high-velocity, seemingly random and erratic manner," Colorado state officials commented.