Scientists from the Arizona Department of Water Resources and the Arizona Geological Survey explain some of the land subsidence and earth fissure problems associated with ground water production in Arizona. The video, When the Ground Splits Open, is by Arizona Public Media.
An article on the New York Times website tells about the Bayou Corne Sinkhole, located in Louisiana above a salt dome where about 25 acres have subsided. The salt dome has been solution mined and the cavities produced by that mining have been used to store a variety of petroleum products.
The interactive Natural Hazard Viewer focuses on four hazards common to Arizona — geologic faults and earthquakes, earth fissures, floods and wildfire. Each hazard is described in detail and displayed as a layer on a map. Moreover, the natural hazard information is dynamic; site updates will occur as new or revised hazard data becomes available.
Editor’s Comment: Every state geological survey should have one of these!
A sinkhole about 200 feet wide and 90 feet deep has opened near the community of Sharon Springs, Kansas. Although no buildings have been damaged there is a problem with visitors venturing close the the edge and climbing in to explore the bottom.
National Geographic has an interesting article about how many small communities on the seaward edge of the Mississippi River delta are being lost to subsidence and sea level rise.
The community of Leeville (shown in Google map below) is featured in the article. If you toggle between “Map” and “Sat” you will see how the map greatly overstates the amount of dry land – at least on the day that the satellite image was acquired.
Most homeowners insurance policies have exclusions that make them worthless when the home is damaged by common geologic problems such as floods, earthquakes, landslides, mine subsidence, cavern collapse and expansive soils. When a home is damaged the homeowner often is surprised that his “all perils” policy has these exclusions.
The Illinois Geological Survey has a publication titled: Karst Landscapes of Illinois. From the publication “Two conditions are necessary for karst landscapes (green areas on map): (1) Soluble rocks, generally limestone and dolostone, must lie at or near the surface of the ground. (2) The loose soil covering the soluble bedrock must be thinner than about 50 feet.”
The Florida Geological Survey has an informative poster titled “Florida’s Sinkholes”. It shows their geographic distribution, explains how they form, describes different sinkhole types, explains why they are a hazard and explains what to do if a sinkhole occurs near your home.
Did you know that most homeowners insurance policies do not cover damage from any type of subsidence? That includes collapse from sinkholes, oil production, ground water pumping and underground mining activity. Most insurance companies offering homeowners coverage exclude almost any type of geologic hazard from coverage – unless you make specific arrangements to acquire it yourself.
Last week a sinkhole opened beneath a home in Florida while the occupants were sleeping. One man’s bed fell into the sink and the efforts of family and rescue workers were not successful in retrieving him. Now he is presumed dead and demolition equipment is there to remove the structure while the sinkhole continues to enlarge. Injuries from sinkholes are rare but this situation shows how suddenly they can occur.
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Homeowners Insurance usually does not cover damage caused by floods, landslides, earthquakes and other geohazards.
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