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Geologic

Geologic hazards exist in all U.S. states and territories and can be caused by a variety of factors, including human modification of land.  Geologic hazards can occur quickly, often with little notice.  The best way to prepare is to stay informed about changes in-and-around your home, workplace, or other location that could signal a geologic issue.


Karst Topography

o   Karst topography forms in regions where rainfall is plentiful and where bedrock consists of carbonate-rich rock, such as limestone, gypsum, or dolomite.  Karst landscape is characterized by caves, sinkholes, fissures and underground streams.

o   The hazards most associated with karst topography is sinkholes, which occur when the roof of a cave becomes too thin to support weight of the bedrock over it, or a fracture in limestone bedrock is enlarged by water dissolving the limestone.

o   The only way to avoid karst hazards is to avoid building structures or living on karst, which is unrealistic.

o   Avoid building or buying a built structure on a sinkhole that has been filled. Do your research on the property, ask questions of the seller, observe geologic conditions around the area of the property, such as shallow depressions and arch-shaped cracks in the soil, and check for damage to structures around or adjacent to the property.

o   If a sinkhole develops under a structure, the foundation should be shored up as quickly as possible.

o   Do not continue to stay in a structure if a sinkhole forms under it or near it.

o   Consult a professional geologist with experience in identifying karst topography and an engineer experienced in sinkhole remediation.


Landslides

o   Landslide problems can be caused by land mismanagement, particularly in mountain, canyon, and coastal regions.  Land-use zoning, professional inspections, and proper design can minimize many landslide problems.

o   Prevent landslides by following proper land-use procedures – avoid building near steep slopes, close to mountain edges, near drainage ways, or along nature erosion valleys.

o   Be familiar with the land around you.  Research the area for any previous landslides.

o   Get a ground assessment of your property and consult a professional for advice on appropriate preventive measures for your home or business.

o   If you are at risk for a landslide, consult your insurance agent.

o   Move away from the path of a landslide as quickly as possible.  List for unusual sounds that might indicate moving debris, such as trees cracking or boulders knocking together.

o   If you are near a stream or channel, be alert for any sudden increase or decrease in water flow and notice whether the water changes from clear to muddy.

o   Curl into a tight ball and protect your head if escape from a landslide is not possible.