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New fissure maps drafted for Arizona

The first in a series of detailed maps of earth fissures caused by excessive groundwater pumping in Pinal County has been released by the Arizona Geological Survey.

In August 2005, monsoon rains opened an earth fissure near Queen Creek. Within days, the fissure became a crevasse tens of feet in length, 5 to 10 feet wide and up to 25 feet deep.

In response to growing public outcry from the incident, the Arizona Legislature drafted a bill that Gov. Janet Napolitano signed to address earth fissures in Arizona, charging AZGS with making comprehensive mapping of earth fissures and delivering earth fissure map data to the State Land Department to be posted online with other GIS map layers that the public may use to build their own customized maps.

Earth fissures form after too much groundwater pumping results in land subsidence. They have plagued homeowners in Pinal and other former farming areas, but they also can be found in more established areas, like around Luke Air Force Base in the western part of the Phoenix metro area.

Roads can be put at risk by the changing landscape, leaving civil engineers to design ways to fix and protect them. The AZGS estimates there are hundreds of earth fissures crisscrossing central and southern Arizona.

The maps and report include a study of previously reported earth fissures in Pinal, Cochise, Maricopa and Pima counties. The data will be displayed at the State Land Department within 90 days. The Web site is www.azgs.az.gov/EFC.html. To buy hard copies of the maps and text, visit the AZGS bookstore at 416 W. Congress, Suite 100, Tucson or in Phoenix at the Arizona Department of Mines and Mineral Resources, 1502 W. Washington St.