Arizona Geology Blog: U.S. 191 in Cochise County damaged by extensive ground fractures
by Joe Cook
U.S. 191, the main north-south highway in central Cochise County, was recently closed due to damage caused by collapse along large surface fractures during a monsoon storm. Local slumping and collapse near milepost 53, southwest of Willcox, began during heavy monsoon rains on the evening of July 5, 2021.
The area surrounding this segment of U.S. 191 is riddled with earth fissures and giant desiccation cracks. Subsidence rates in this area are on the order of 16 cm (6 in)/year. U.S. 191 is open to traffic.
The blog includes four figures and online resources concerning earth fissures in south-central and southeastern Arizona.
Image: Overview of polygonal cracks and AZGS site observations. Polygonal GDC networks are present along both sides of U.S. 191 and some new cracks have formed since this aerial photo was taken (2016). Areas 1 and 2 are zones of wetted soil where rainwater infiltrates. Yellow dots represent observed surface cracks on July 8, 2021. Not all photo-interpreted cracks were visited.
Citation. Cook, J.P., 2021, U.S. 191 in Cochise County damaged by extensive ground fractures. Arizona Geology Blog (7/19/2021).