[meteorite-list] Guatemala City Sinkhole was "OT- Non Meteorite Crater Photo"

[Paul H.]

Ryan wrote:

“Sinkholes are usually formed by the collapse of a void 
underground. Typically this happens in limestone/marble/
carbonate rocks (where caves are normally formed) 
because rainwater + CO2 (dissolved in H20) creates a 
weak (carbonic) acid that eats at the CaCO3 of the 
carbonate rocks (as it seeps down cracks), and begins 
creating a gap. As the gap gets larger, more water flows 
in, accelerating  the process, until, eventually, a cavity 
too large to support itself is created an collapses, thus 
creating a sink hole.”

After finally finding a geologic map, I found that Guatemala
City is underlain by limestone, which perfectly explains
the sinkhole. Still, this is a classic example of a sinkhole
and the hazards that they pose to people and structures
in urban areas.,

Some of the largest examples of sinkholes are in China 
where entire cave systems have collapsed producing 
sinkholes that are called “tiankengs”. These sinkholes 
are 100s of meters in diameters in diameter and deep.

For example:

Tiankengs in the karst of China by Zhu Xuewen and 
Chen Weihai in Speleogenesis and Evolution of Karst 
Aquifers at:
http://www.speleogenesis.info/pdf/SG9/SG9_artId3290.pdf

Tiankengs of the world, outside China by Tony Waltham
Speleogenesis and Evolution of Karst Aquifers
http://www.speleogenesis.info/pdf/SG9/SG9_artId3291.pdf

Introduction to Karst Tiankeng in China
http://theculturedtraveler.com/Archives/Nov2005/Karst_Tiankeng.htm

Yours,

Paul H.