Ground Fissuring

Primary reference(s)

Arizona Geological Survey, 2020. Earth Fissures and Ground Subsidence. Accessed 20 October 2020.

Additional scientific description

Natural or anthropogenic ground desiccation associated with subsidence can lead to ground fissuring. Ground fissures may also form as incipient indicators of coastal land sliding, ground spreading or cambering, for example, induced by mining or karst subsidence.

Ayalew et al. (2004) suggested that ground fissures in the Ethiopian rift valley may be related to aseismic tectonic strain, piping and hydraulic compaction.

Surface fissures are also associated with earthquakes.

The size and spatial extent of surface rupture, fissures and uplift/subsidence depends on the type and context. In Arizona, fissures range from discontinuous hairline fractures to open ground cracks that exceed 3 km in length, are up to 7 m wide, and tens of metres deep. In this context, fissure depth is likely to reflect the depth to the groundwater (Arizona Geological Survey, 2020).

Metrics and numeric limits

Not identified.

Examples of drivers, outcomes and risk management

Ground fissures can cause loss of agricultural land, and damage to buildings, roads, canals and utility infrastructure (e.g., gas, oil and water lines). In addition to the immediate, local risk posed by collapsing infrastructure, this damage may hamper rescue and rebuilding efforts by impeding transportation and utility delivery. In the worst cases, damage to lifelines may cause local flooding (e.g., water lines), environmental impacts (e.g., contamination) and fires (gas lines) (Arizona Geological Survey, 2020).

The potential also exists for disruption due to flooding or re-routing of rivers if the river channel has been sufficiently modified (Holbrook and Schumm, 1999).

Livestock and wildlife injury or death have been reported as well as impacts on humans (Arizona Geological Survey, 2020).

Ground subsidence and resulting earth fissures affect more than 3000 square miles in Arizona, including expanding areas of Phoenix and Tucson (Arizona Geological Survey, 2020). The cost to the Arizona economy is not known, but probably reaches the millions of dollars annually. Repairs to an irrigation canal near Scottsdale Airpark in 2007 were estimated at USD 820,000, and that is just a single incident involving one canal. During construction of the Red Mountain Highway in Phoenix, the cost of mitigating an earth fissure that impinged on the road bed was USD 200,000 (Arizona Geological Survey, 2020).

Suggested remedial measures include reducing the dependence on groundwater by using alternative sources; planning to avoid fissures when constructing infrastructure or buildings; manage drainage to avoid losses into fissures and monitor water infrastructure for flow reversal (Arizona Geological Survey, 2020).