AZGS is releasing new earth fissure maps today for Elfrida, Croton Springs, and Three Sisters Buttes, Cochise County, and Picacho and Friendly Corners in Pinal County. The new maps come with a new format that includes a high-resolution air photo base and subsidence maps from the Arizona Dept. of Water Resources InSAR satellite monitoring program.
AZGS’s earth fissure map format has been substantially revamped to make the maps easier to use and to include subsidence maps for valleys hosting earth fissures. The new map format incorporates a high-resolution, air photo base map compiled from 1-meter resolution National Agriculture Imagery Program imagery (2010), and ground subsidence maps from the Arizona Department of Water Resource InSAR (Interferometric Synthetic Aperture Radar) satellite land subsidence monitoring program. Subsidence, as shown on the InSAR inset map, is measured in centimeters.
The Picacho-Friendly Corners area, Pinal County, and Three Sisters Buttes, [above] Cochise County earth fissure study area maps are reissued in this new map format as well.
Arizona Geological Survey geologists mapped about 1.6 miles (~8,800 feet)of continuous and discontinuous earth fissures in the Elfrida (~7,100 feet) and Croton Springs (~1,700 feet) areas.
In Cochise County, earth fissure maps are available for the following areas:
Three Sisters Buttes
The Dragoon Road and Bowie-San Simon maps will be reissued in the new format in the near future. The Sulphur Springs North earth fissure study area just north of Willcox in Cochise County remains to be mapped.
AZGS’s Earth Fissure Viewer [bottom map] shows the footprints of all previously mapped fissure study areas and provides links to free, downloadable PDFs. A Geographic Information System (GIS)file showing the locations of mapped earth fissure traces in Arizona should be available for download shortly.
Besides posing a threat to infrastructure and livestock, fissures are an illegal dumping ground for tires, appliances, construction debris, manure and other sundry items. Because the fissures are believed to extend down to the water table, earth fissures represent a potential threat by serving as a conduit from surface runoff contaminating groundwater resources.
The AZGS Earth Fissure Mapping Program will continue to update maps as earth fissures grow and new ones form. AZGS geologists will begin focusing on ways to predict where and when the fissures will appear and work with local building officials and engineers on way to mitigate existing earth fissures to minimize their impacts.