Back in 2006, legislation was passed requiring the Arizona Geological Survey (AZGS) to deliver:

• A comprehensive mapping of earth fissures throughout Arizona
• Detailed earth fissure map data to the State Land Department for public access online

The first two such maps for Chandler Heights / Queen Creek and Apache Junction (areas particularly prone to earth fissures) have been released (PDF format). In addition, there’s an interactive map site now available.

The interactive map is slow and tedious, and doesn’t appear yet to have any real advantage over the PDF maps.

“What’s an earth fissure?” you may be asking yourself. In a nutshell (that will have geologists cringing, I’m sure) earth fissures and subsidence occurs in certain areas when too much ground water is pumped out, causing cracks and collapses of the surrounding earth to occur.

Why are earth fissures important to home owners?

Because no one wants to walk out the door one day and see this running through their front yard:

Things like this can do extensive damage to buildings, roads, pipelines, etc.

Why are earth fissures more common in some areas like Chandler Heights and Apache Junction?

Clearly I am not a geologist nor an expert in ground water or ground water extraction. But it has to do with the underlying topography of the earth, it’s structure and what not (“what not” being the technical term). If you look at the maps, you’ll see the fissures tend to lie along the bases of mountains (not ALL mountains) as well as water drainage/runoff areas. The links below cover the process in detail.

More information on earth fissures can be found at the AZGS Earth Fissure Center, or this fabulous “white paper”, LAND SUBSIDENCE & EARTH FISSURES IN ARIZONA. (21 pages, PDF).

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