The first county-wide compilation of earth fissures in Pinal County is now complete. Maps of the final three earth fissure study areas -- Sacaton Butte, Santa Rosa Wash, and White Horse Pass -- are available online at the Earth Fissure Viewer. The comprehensive Pinal County Earth Fissure Map (1:250,000 map scale) showing all mapped and reported earth fissures in the county is available in PDF format.
Over the past three years, Arizona Geological Survey geologists mapped 86 miles of continuous and discontinuous earth fissures in Pinal County. An additional 167 miles of reported fissures were visited and examined but remain unconfirmed either because recent agricultural or construction activities masked their appearance or because they lack some of the physical attributes used to identify earth fissures.
Nearly 43 miles (50%) of all mapped fissures are exposed on the east side of the Picacho Basin, adjacent to the Picacho Mountains and Picacho Peak. The three newly mapped study areas yielded 5.62 miles of earth fissures, with Santa Rosa Wash accounting for nearly three miles of that. An additional 7.7 miles of previously reported fissures remain unconfirmed.
AZGS monitors growth of existing earth fissures and investigates formation of new ones. As complete the first state-wide compilation of known fissures, we will move into prediction and mitigation phases.