A surgical mask is used inside the operating room or during other sterile procedure areas to protect the patient environment from contamination. Surgical masks have ties so that they can be adjusted for fit, and are tied over the top of a surgical or bouffant cap.
rockfall. 1  an act or instance of the falling of rock, as in a cave-in or an avalanche. 2  a mass of rocks that have fallen: to be trapped under a rockfall.
Debris Flow Hazards Debris Flow Hazards Fast-moving landslides that can attain speeds over 30 miles per hour. Volcanic Mudflows Lahars are mudflows that are composed of volcanic debris and water. Yosemite Rock Fall Yosemite Rock Fall Hazards Learn what the Park Service is doing to reduce rock fall hazard.ock Fall Photos Yosemite Rock Fall Photos A photo sequence of a rockfall and debris avalanche by Herb Dunn. Largest Tsunami Largest Tsunami The wave with the highest run-up was triggered by a rock fall. Largest Landslides Largest Landslides Heart Mountain and Storegga-Earth\'s largest known landslides.