When do subsidences normally occur and where did an example of this appear in 1986?

-- randy rosenthal (rrosenth@oswego.edu), April 16, 2001

Answers

I found that subsidence is a gradual or abrupt collapse of underground layers above a coal mine. I remember last week Dr. Isley talking about a collapse in the ground underneath a lake and all of it jcreating a whirlpool into the ground where the were workers laying pipe line or something like that. Maybe this is what you're referring to in 1986.

-- Deb Richards (Kizmet727@yahoo.com), April 17, 2001.

I believe what you are looking for was from Dr.Isley discussion that said the subsidences typically occur with harvesting rich rock. An example would have be the Allentown, Penn subsidence 30 meter diameter and 14 meters deep.

-- Colin Elder (belder23@aol.com), April 20, 2001.