Today I-70 will be closed between Empire and Silverthorne for rockfall mitigation in the Georgetown area. There is a large, unstable cluster of boulders above the highway that will be removed. More information about the closure is available on the Colorado Department of Transportation website.
If you are curious about rockfall and why it happens, a great place to start is “Rockfall in Colorado” an issue of RockTalk from the Colorado Geological Survey. It has basic information on rockfalls and how rockfall events can be mitigated or avoided.
If you are more interested in the geological details and rockfall risk assessment, check out “Modification and Statistical Analysis of the Colorado Rockfall Hazard Rating System.” This report details a fascinating study conducted by the Colorado Department of Transportation, that analyzes the geological structures around Colorado, and ranks them based on the likelihood of potential rockfall.
The Colorado Geological Survey’s rockfall website is another useful source of information.