Land Subsidence, Earth Fissures, and Water-Level Change in Southern Arizona

An extensive review of leveling information by Strange (1983) Indicated that measurable land subsidence had been detected In nine ground-water areas. Subsidence was first detected In southern Arizona In 1948 through releveling of bench marks near Eloy In the lower Santa Cruz basin (Robinson and Peterson. 1962) . Subsequent investigations indicated that land subsidence was continuing near Eloy and that the areas of greatest subsidence corresponded to the areas of greatest water- level decline (Schumann and Poland. 1970) By 1977 about 425 mi2 in the Stanfield area and 675 mi2 in the Etoy area were affected by subsidence in southern Pinal County (Schumann and others, 1986). By 1977, 11.8 ft and 12.5 ft of subsidence had occurred near Stanfield and Eloy. respectively (Laney and others. 1978). In 1985 more than 15 ft of subsidence was measured south of Eloy (Carl C. Winikka, Arizona Department of Transportation. written commun., 1985). In the western part of Salt River Valley, an area of 140 mi2 near Luke Air Force Base west of Phoenix and an area of 230 mi2 near Queen Creek were reported to have subsided more than 3 ft by 1977 (Poland, 1981). Water-level declines prior to 1977 In both areas exceeded 300 ft. Between 1948 and 1981. about 5.2 ft of subsidence was measured east of Mesa. where water-level declines had exceeded 300 ft by 1977 (Strange. 1983)Documents in the AZGS Documents Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact azgs-info@email.arizona.edu