Earth Fissure Map of the Picacho & Friendly Corners Study Area: Pinal County, Arizona v 3.0
AuthorArizona Geological Survey
KeywordsArizona Geological Survey Digital Maps (DM)
earth fissure maps
MetadataShow full item record
CitationArizona Geological Survey, 2016, Earth Fissure Map of the Picacho & Friendly Corners Study Area: Pinal County, Arizona v. 3.0. Arizona Geological Survey Digital Map - Earth Fissure (DM-EF-03, v3.0), 3 map sheets, 1:24,000 map scale.
PublisherArizona Geological Survey (Tucson, AZ)
DescriptionThis is one of a series of earth fissure maps prepared by the Arizona Geological Survey (“AZGS”) in accordance with Ariz. Rev. Stat. § 27-152.01(3). AZGS collected location information from previously conducted earth fissure studies, reviewed available remote-sensing aerial and satellite imagery, and conducted surface site investigations throughout the study area. A reasonable effort was made to identify all earth fissures in the study area. Nonetheless, some fissures may remain unmapped as a result of one or more of the following: 1) existing fissures may have been masked by construction or agricultural activities; 2) incipient fissures may lack clear surface expression; 3) the surface expression of fissures changes constantly as new earth fissures develop and old earth fissures fill in. A blank area on the map does not guarantee earth fissures are not present. However, blank areas within the study area boundary have been investigated, and no surface evidence of fissures was found as of the date of map publication. Determining the presence or absence of a fissure at any specific site may require additional mapping and/or geotechnical analysis.
Series/Report no.DM-EF-3 v 3.0
RightsArizona Geological Survey. All rights reserved.
Collection InformationDocuments in the AZGS Document 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 firstname.lastname@example.org.
North Bounding Coordinate32.9128
South Bounding Coordinate32.5802
West Bounding Coordinate-111.577
East Bounding Coordinate-111.399
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Earth-fissure movements associated with fluctuations in ground-water levels near the Picacho mountains, south-central Arizona, 1980-84Carpenter, Michael C.; Davis, Stanley N.; Simpson, Eugene S.; Wilson, L. G. (The University of Arizona., 1993)The Picacho earth fissure transects subsiding alluvial sediments near the eastern periphery of the Picacho basin in southcentral Arizona. The basin has undergone land subsidence of as much as 3.8 m since the 1930's due to compaction of the aquifer system in response to ground-water-level declines that have exceeded 100 m. The fissure extends generally north-south for 15 km and exhibits horizontal tensile failure as well as up to 0.6 m of normal dip-slip movement at the land surface, with the west side of the fissure downthrown. The fissure was observed as early as 1927, following an earthquake, and is the longest earth fissure in Arizona. Vertical and horizontal displacements have been monitored along a line normal to the fissure. The survey line extends from a bedrock outcrop in the Picacho Mountains on the east, past an observation well near the fissure, to a point 1422 in to the west. From May 1980 to May 1984, the western, downthrown side of the fissure subsided 167 ±1.8 mm and moved 18 ±1.5 mm westward into the basin. Concurrently, the eastern, relatively upthrown side subsided 147 ±1.8 mm and moved 14 ±1.5 mm westward. Dislocation modeling of deformation along the survey line near the fissure suggests that dip-slip movement has occurred along a vertical fault surface that extends from the land surface to a depth of about 300 m. Slip was 9 mm from May to December 1980 and 9 mm from March to November 1981. Continuous measurements were made of horizontal movement across the fissure using a buried invar-wire horizontal extensometer, while water-level fluctuations were continuously monitored in four piezometers nested in two observation wells. The range of horizontal movement was 4.620 mm, and the range of water-level fluctuation in the nearest piezometer in the deeper alluvium was 9.05 m. The maximum annual opening of the fissure during the study period was 3.740 mm from March to October 1981, while the water-level declined 7.59 m. The fissure closed 1.033 mm from October 1981 to March 1982 while the water level recovered 6.94 m. Opening and closing of the fissure were smooth and were correlated with water-level decline and recovery, respectively, in the nearby piezometers. Pearson correlation coefficients between the water-level fluctuations in the deeper piezometers and horizontal movement ranged from 0.913 to 0.925. The correlogram of water-level decline as ordinate, versus horizontal strain as abscissa, exhibits hysteresis loops for annual cycles of water-level fluctuation as well as near-vertical excursions for shorter cycles of pumping and recovery.