On January 23, 2017 the Arizona Geological Survey (AZGS) posted a YouTube video. below from an aerial drone showing a large, newly discovered earth fissure. Viewed more than 650,000 times, the video has generated great public interest and captured the attention of numerous local, regional and national media outlets, resulting in more than two dozen news articles.
Located approximately 13 miles SSE of Arizona City in southern Pinal County, this roughly north-south oriented crevasse ranges up to 10 feet wide and 30 feet deep. Satellite imagery from Google Earth shows that the northern portion of the earth fissure developed between March 2014 and December 2014, possibly coinciding with heavy precipitation that occurred during the fall of 2014. Since December 2014, this ground fracture has grown southward and now measures approximately 9,500 feet in length. Additional information on this earth fissure can be found in Arizona Geological Survey Open File Report 17–1.
Since the early decades of the 20th century, groundwater pumping from aquifers in unconsolidated basin sediments of central and southeastern Arizona has resulted in land subsidence in a number of valleys, including more than 15 feet of subsidence in the Eloy area between 1952 and 1985. Subsidence in some Arizona valleys was accompanied by the formation of earth fissures; tension cracks that occur in areas of differential land subsidence. The first fissures were observed in the Eloy area in 1927. Since then, earth fissures have been identified and mapped in Cochise, La Paz, Maricopa, Pima and Pinal counties – see AZGS’ Natural Hazards in Arizona Viewer for the distribution of more than 175 miles of mapped earth fissures.
In rural areas fissures pose a hazard to livestock, hikers and off-road enthusiasts, who may fall into the larger crevasses. But as agricultural lands become more urbanized, earth fissures are impacting property values and damaging and disrupting infrastructure, such as roads, canals, homes, buildings, gas lines and other utilities. In the densely populated Phoenix Valley, communities impacted by earth fissures include: Chandler Heights, Apache Junction, Queen Creek, Scottsdale and the area north of Litchfield Park near Luke Air Force Base in the western valley.
The Arizona Geological Survey’s core mission involves informing and advising its stakeholders – Arizona public, industry, business and state, local and tribal government – on geological processes, materials and landscapes and in the prudent use of lands and mineral resources. Identifying natural hazards such as landslides, debris flows, areas prone to flooding, earth fissures, subsidence from groundwater withdrawals, expansive soils and earthquakes are core functions of the survey. Both private and public sectors have benefited from the AZGS’ collection and analysis of basic scientific data and the compilation of maps and reports on Arizona’s geology.
In July 2016 the AZGS was transferred to the University of Arizona’s College of Science and its annual state appropriation zeroed out. This led to substantial cuts in personnel and seriously impairs the survey’s ability to maintain its core, state statute established services at pre-2017 levels.
Unless essential funding for the AZGS’ core programs is reinstated by the Arizona State Legislature and approved by Governor Ducey, these services may continue to decline or could be suspended entirely.
Arizona’s FY 2018 state budget is currently winding its way through the legislative process. SB1184, re-establishing annual base funding of $941,000 for the AZGS, passed the Arizona Senate Appropriations Committee 9-1 on Tuesday, February 14, 2017. While this appropriation vote was a big step forward, several more hurdles must be cleared before funding becomes a reality.
The recent discovery of a major earth fissure near Arizona City only reinforces the need to restore funding to the Arizona Geological Survey. Arizona’s future growth and prosperity depends on our understanding of dynamic geological processes that continue to shape Arizona’s landscapes and the wise use of our lands and mineral resources. Having dealt with these issues since its creation in 1888, the Arizona Geological Survey is well positioned to meet the future needs of Arizonans.
David F. Briggs is a retired geologist residing in Tucson, Arizona. Email him at MiningandYou@aol.com.