March 26, 2003
The withdrawal of groundwater in some parts of Arizona has resulted in land subsidence of several meters in broad valley basins. As water is withdrawn without being replenished, the deep sediments settle. Buried shelves of bedrock cause unexpected ground fissures to open in some places. This can be a hazard to buildings and highways as some of them are as much as several meters wide and five meters or more deep. These cracks usually open slowly over a period of weeks or more, and have no connection to earthquakes. This recently opened fissure is on the outskirts of Mesa, Arizona, east of Phoenix.